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  Subjects -> CHEMISTRY (Total: 894 journals)
    - ANALYTICAL CHEMISTRY (55 journals)
    - CHEMISTRY (628 journals)
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    - INORGANIC CHEMISTRY (43 journals)
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    - PHYSICAL CHEMISTRY (71 journals)

CHEMISTRY (628 journals)                  1 2 3 4 | Last

Showing 1 - 200 of 735 Journals sorted alphabetically
2D Materials     Hybrid Journal   (Followers: 14)
Accreditation and Quality Assurance: Journal for Quality, Comparability and Reliability in Chemical Measurement     Hybrid Journal   (Followers: 28)
ACS Catalysis     Hybrid Journal   (Followers: 44)
ACS Chemical Neuroscience     Hybrid Journal   (Followers: 22)
ACS Combinatorial Science     Hybrid Journal   (Followers: 23)
ACS Macro Letters     Hybrid Journal   (Followers: 26)
ACS Medicinal Chemistry Letters     Hybrid Journal   (Followers: 42)
ACS Nano     Hybrid Journal   (Followers: 303)
ACS Photonics     Hybrid Journal   (Followers: 14)
ACS Symposium Series     Full-text available via subscription  
ACS Synthetic Biology     Hybrid Journal   (Followers: 24)
Acta Chemica Iasi     Open Access   (Followers: 5)
Acta Chimica Slovaca     Open Access   (Followers: 2)
Acta Chimica Slovenica     Open Access   (Followers: 1)
Acta Chromatographica     Full-text available via subscription   (Followers: 8)
Acta Facultatis Medicae Naissensis     Open Access  
Acta Metallurgica Sinica (English Letters)     Hybrid Journal   (Followers: 7)
Acta Scientifica Naturalis     Open Access   (Followers: 3)
adhäsion KLEBEN & DICHTEN     Hybrid Journal   (Followers: 8)
Adhesion Adhesives & Sealants     Hybrid Journal   (Followers: 9)
Adsorption Science & Technology     Open Access   (Followers: 6)
Advanced Functional Materials     Hybrid Journal   (Followers: 60)
Advanced Science Focus     Free   (Followers: 5)
Advances in Chemical Engineering and Science     Open Access   (Followers: 73)
Advances in Chemical Science     Open Access   (Followers: 18)
Advances in Chemistry     Open Access   (Followers: 23)
Advances in Colloid and Interface Science     Full-text available via subscription   (Followers: 19)
Advances in Drug Research     Full-text available via subscription   (Followers: 25)
Advances in Environmental Chemistry     Open Access   (Followers: 7)
Advances in Enzyme Research     Open Access   (Followers: 10)
Advances in Fluorine Science     Full-text available via subscription   (Followers: 9)
Advances in Fuel Cells     Full-text available via subscription   (Followers: 16)
Advances in Heterocyclic Chemistry     Full-text available via subscription   (Followers: 12)
Advances in Materials Physics and Chemistry     Open Access   (Followers: 26)
Advances in Nanoparticles     Open Access   (Followers: 15)
Advances in Organometallic Chemistry     Full-text available via subscription   (Followers: 17)
Advances in Polymer Science     Hybrid Journal   (Followers: 45)
Advances in Protein Chemistry     Full-text available via subscription   (Followers: 18)
Advances in Protein Chemistry and Structural Biology     Full-text available via subscription   (Followers: 20)
Advances in Quantum Chemistry     Full-text available via subscription   (Followers: 6)
Advances in Science and Technology     Full-text available via subscription   (Followers: 12)
African Journal of Bacteriology Research     Open Access  
African Journal of Chemical Education     Open Access   (Followers: 3)
African Journal of Pure and Applied Chemistry     Open Access   (Followers: 8)
Agrokémia és Talajtan     Full-text available via subscription   (Followers: 2)
Al-Kimia : Jurnal Penelitian Sains Kimia     Open Access  
Alchemy : Journal of Chemistry     Open Access   (Followers: 3)
Alkaloids: Chemical and Biological Perspectives     Full-text available via subscription   (Followers: 2)
AMB Express     Open Access   (Followers: 1)
Ambix     Hybrid Journal   (Followers: 3)
American Journal of Biochemistry and Biotechnology     Open Access   (Followers: 69)
American Journal of Biochemistry and Molecular Biology     Open Access   (Followers: 22)
American Journal of Chemistry     Open Access   (Followers: 32)
American Journal of Plant Physiology     Open Access   (Followers: 11)
American Mineralogist     Hybrid Journal   (Followers: 16)
Anadolu University Journal of Science and Technology A : Applied Sciences and Engineering     Open Access  
Analyst     Full-text available via subscription   (Followers: 38)
Angewandte Chemie     Hybrid Journal   (Followers: 179)
Angewandte Chemie International Edition     Hybrid Journal   (Followers: 256)
Annales UMCS, Chemia     Open Access   (Followers: 1)
Annals of Clinical Chemistry and Laboratory Medicine     Open Access   (Followers: 5)
Annual Reports in Computational Chemistry     Full-text available via subscription   (Followers: 3)
Annual Reports Section A (Inorganic Chemistry)     Full-text available via subscription   (Followers: 4)
Annual Reports Section B (Organic Chemistry)     Full-text available via subscription   (Followers: 9)
Annual Review of Chemical and Biomolecular Engineering     Full-text available via subscription   (Followers: 12)
Annual Review of Food Science and Technology     Full-text available via subscription   (Followers: 13)
Anti-Infective Agents     Hybrid Journal   (Followers: 3)
Antiviral Chemistry and Chemotherapy     Open Access   (Followers: 2)
Applied Organometallic Chemistry     Hybrid Journal   (Followers: 9)
Applied Spectroscopy     Full-text available via subscription   (Followers: 24)
Applied Surface Science     Hybrid Journal   (Followers: 32)
Arabian Journal of Chemistry     Open Access   (Followers: 6)
ARKIVOC     Open Access   (Followers: 1)
Asian Journal of Biochemistry     Open Access   (Followers: 3)
Asian Journal of Chemistry and Pharmaceutical Sciences     Open Access  
Atomization and Sprays     Full-text available via subscription   (Followers: 4)
Australian Journal of Chemistry     Hybrid Journal   (Followers: 7)
Autophagy     Hybrid Journal   (Followers: 3)
Avances en Quimica     Open Access  
Biochemical Pharmacology     Hybrid Journal   (Followers: 11)
Biochemistry     Hybrid Journal   (Followers: 376)
Biochemistry Insights     Open Access   (Followers: 6)
Biochemistry Research International     Open Access   (Followers: 6)
BioChip Journal     Hybrid Journal  
Bioinorganic Chemistry and Applications     Open Access   (Followers: 11)
Bioinspired Materials     Open Access   (Followers: 5)
Biointerface Research in Applied Chemistry     Open Access   (Followers: 2)
Biointerphases     Open Access   (Followers: 1)
Biology, Medicine, & Natural Product Chemistry     Open Access   (Followers: 2)
Biomacromolecules     Hybrid Journal   (Followers: 22)
Biomass Conversion and Biorefinery     Partially Free   (Followers: 10)
Biomedical Chromatography     Hybrid Journal   (Followers: 6)
Biomolecular NMR Assignments     Hybrid Journal   (Followers: 3)
BioNanoScience     Partially Free   (Followers: 5)
Bioorganic & Medicinal Chemistry     Hybrid Journal   (Followers: 138)
Bioorganic & Medicinal Chemistry Letters     Hybrid Journal   (Followers: 87)
Bioorganic Chemistry     Hybrid Journal   (Followers: 10)
Biopolymers     Hybrid Journal   (Followers: 18)
Biosensors     Open Access   (Followers: 2)
Biotechnic and Histochemistry     Hybrid Journal   (Followers: 1)
Bitácora Digital     Open Access  
Boletin de la Sociedad Chilena de Quimica     Open Access  
Bulletin of the Chemical Society of Ethiopia     Open Access   (Followers: 1)
Bulletin of the Chemical Society of Japan     Full-text available via subscription   (Followers: 24)
Bulletin of the Korean Chemical Society     Hybrid Journal   (Followers: 1)
C - Journal of Carbon Research     Open Access   (Followers: 3)
Cakra Kimia (Indonesian E-Journal of Applied Chemistry)     Open Access  
Canadian Association of Radiologists Journal     Full-text available via subscription   (Followers: 2)
Canadian Journal of Chemistry     Hybrid Journal   (Followers: 11)
Canadian Mineralogist     Full-text available via subscription   (Followers: 6)
Carbohydrate Research     Hybrid Journal   (Followers: 26)
Carbon     Hybrid Journal   (Followers: 70)
Catalysis for Sustainable Energy     Open Access   (Followers: 8)
Catalysis Reviews: Science and Engineering     Hybrid Journal   (Followers: 7)
Catalysis Science and Technology     Free   (Followers: 8)
Catalysis Surveys from Asia     Hybrid Journal   (Followers: 3)
Catalysts     Open Access   (Followers: 11)
Cellulose     Hybrid Journal   (Followers: 9)
Cereal Chemistry     Full-text available via subscription   (Followers: 5)
ChemBioEng Reviews     Full-text available via subscription   (Followers: 1)
ChemCatChem     Hybrid Journal   (Followers: 8)
Chemical and Engineering News     Free   (Followers: 22)
Chemical Bulletin of Kazakh National University     Open Access  
Chemical Communications     Full-text available via subscription   (Followers: 75)
Chemical Engineering Research and Design     Hybrid Journal   (Followers: 27)
Chemical Research in Chinese Universities     Hybrid Journal   (Followers: 3)
Chemical Research in Toxicology     Hybrid Journal   (Followers: 22)
Chemical Reviews     Hybrid Journal   (Followers: 204)
Chemical Science     Open Access   (Followers: 27)
Chemical Technology     Open Access   (Followers: 32)
Chemical Vapor Deposition     Hybrid Journal   (Followers: 5)
Chemie in Unserer Zeit     Hybrid Journal   (Followers: 57)
Chemie-Ingenieur-Technik (Cit)     Hybrid Journal   (Followers: 24)
ChemInform     Hybrid Journal   (Followers: 8)
Chemistry & Biodiversity     Hybrid Journal   (Followers: 7)
Chemistry & Biology     Full-text available via subscription   (Followers: 33)
Chemistry & Industry     Hybrid Journal   (Followers: 8)
Chemistry - A European Journal     Hybrid Journal   (Followers: 166)
Chemistry - An Asian Journal     Hybrid Journal   (Followers: 16)
Chemistry and Materials Research     Open Access   (Followers: 21)
Chemistry Central Journal     Open Access   (Followers: 4)
Chemistry Education Research and Practice     Free   (Followers: 5)
Chemistry in Education     Open Access   (Followers: 9)
Chemistry International     Open Access   (Followers: 3)
Chemistry Letters     Full-text available via subscription   (Followers: 45)
Chemistry of Materials     Hybrid Journal   (Followers: 266)
Chemistry of Natural Compounds     Hybrid Journal   (Followers: 9)
Chemistry World     Full-text available via subscription   (Followers: 20)
Chemistry-Didactics-Ecology-Metrology     Open Access   (Followers: 1)
ChemistryOpen     Open Access   (Followers: 1)
Chemkon - Chemie Konkret, Forum Fuer Unterricht Und Didaktik     Hybrid Journal  
Chemoecology     Hybrid Journal   (Followers: 3)
Chemometrics and Intelligent Laboratory Systems     Hybrid Journal   (Followers: 15)
Chemosensors     Open Access  
ChemPhysChem     Hybrid Journal   (Followers: 12)
ChemPlusChem     Hybrid Journal   (Followers: 2)
ChemTexts     Hybrid Journal  
CHIMIA International Journal for Chemistry     Full-text available via subscription   (Followers: 2)
Chinese Journal of Chemistry     Hybrid Journal   (Followers: 6)
Chinese Journal of Polymer Science     Hybrid Journal   (Followers: 11)
Chromatographia     Hybrid Journal   (Followers: 23)
Chromatography     Open Access   (Followers: 2)
Chromatography Research International     Open Access   (Followers: 6)
Cogent Chemistry     Open Access   (Followers: 2)
Colloid and Interface Science Communications     Open Access  
Colloid and Polymer Science     Hybrid Journal   (Followers: 11)
Colloids and Interfaces     Open Access  
Colloids and Surfaces B: Biointerfaces     Hybrid Journal   (Followers: 6)
Combinatorial Chemistry & High Throughput Screening     Hybrid Journal   (Followers: 4)
Combustion Science and Technology     Hybrid Journal   (Followers: 22)
Comments on Inorganic Chemistry: A Journal of Critical Discussion of the Current Literature     Hybrid Journal   (Followers: 2)
Communications Chemistry     Open Access  
Composite Interfaces     Hybrid Journal   (Followers: 7)
Comprehensive Chemical Kinetics     Full-text available via subscription   (Followers: 1)
Comptes Rendus Chimie     Full-text available via subscription  
Comptes Rendus Physique     Full-text available via subscription   (Followers: 1)
Computational and Theoretical Chemistry     Hybrid Journal   (Followers: 9)
Computational Biology and Chemistry     Hybrid Journal   (Followers: 12)
Computational Chemistry     Open Access   (Followers: 2)
Computers & Chemical Engineering     Hybrid Journal   (Followers: 10)
Coordination Chemistry Reviews     Full-text available via subscription   (Followers: 4)
Copernican Letters     Open Access   (Followers: 1)
Corrosion Series     Full-text available via subscription   (Followers: 7)
Critical Reviews in Biochemistry and Molecular Biology     Hybrid Journal   (Followers: 8)
Croatica Chemica Acta     Open Access  
Crystal Structure Theory and Applications     Open Access   (Followers: 4)
CrystEngComm     Full-text available via subscription   (Followers: 13)
Current Catalysis     Hybrid Journal   (Followers: 2)
Current Chromatography     Hybrid Journal  
Current Green Chemistry     Hybrid Journal   (Followers: 1)
Current Metabolomics     Hybrid Journal   (Followers: 5)
Current Microwave Chemistry     Hybrid Journal  
Current Opinion in Colloid & Interface Science     Hybrid Journal   (Followers: 9)
Current Opinion in Molecular Therapeutics     Full-text available via subscription   (Followers: 14)
Current Research in Chemistry     Open Access   (Followers: 9)
Current Science     Open Access   (Followers: 73)
Current Trends in Biotechnology and Chemical Research     Open Access   (Followers: 3)
Dalton Transactions     Full-text available via subscription   (Followers: 23)
Detection     Open Access   (Followers: 4)
Developments in Geochemistry     Full-text available via subscription   (Followers: 2)

        1 2 3 4 | Last

Journal Cover
Applied Surface Science
Journal Prestige (SJR): 1.093
Citation Impact (citeScore): 4
Number of Followers: 32  
 
  Hybrid Journal Hybrid journal (It can contain Open Access articles)
ISSN (Print) 0169-4332
Published by Elsevier Homepage  [3155 journals]
  • Homogeneity and penetration depth of atmospheric pressure plasma
           polymerization onto electrospun nanofibrous mats
    • Abstract: Publication date: 31 March 2019Source: Applied Surface Science, Volume 471Author(s): Miroslav Michlíček, Anton Manakhov, Eva Dvořáková, Lenka Zajíčková This work investigates for the first time the penetration depth, nanoscopic homogeneity and conformality of the plasma polymerization onto an electrospun nanofibrous mat. The study is carried out on the model example of atmospheric pressure plasma co-polymerization of anhydride-rich films onto polycaprolactone mats that can find a significant practical applications, for example in tissue engineering and regenerative medicine. Since the surface-to-volume ratio of nanofibrous mats is enormous and the structure of mats resembles extracellular matrix the successful plasma coating of each whole fiber and understanding the penetration of the polymerization into the mat structure are extremely important. The films with reactive anhydride groups were prepared by co-polymerization of maleic anhydride and acetylene using dielectric barrier discharge. The studies were accompanied by the quantification of anhydride groups directly on the PCL electrospun mat using the chemical derivatization with trifluoroethylamine and X-ray photoelectron spectroscopy. The nanoscopic homogeneity and conformality of the anhydride plasma polymer coating on the front side and backside of the nanofibrous mat, 30–40 μm in thickness, did not differ according to the dynamic SIMS mapping. The films containing approximately 6 anhydride groups per 100 carbon atoms coated homogeneously the nanofibers deeper in the PCL mat. The characteristic penetration depth of the deposition was estimated as 46 ± 5 μm.
       
  • Nanosheet-like Ni-based metasilicate towards the regulated catalytic
           activity in styrene oxidation via introducing heteroatom metal
    • Abstract: Publication date: 31 March 2019Source: Applied Surface Science, Volume 471Author(s): Fu Yang, Bo Shao, Xianfeng Liu, Shuying Gao, Xu Hu, Man Xu, Yun Wang, Shijian Zhou, Yan Kong Multiple catalytic active centers tactically generated on the 2-dimentional catalytic carrier could afford certain promoting function thanks to their existed special synergy. Herein, Ni-based nanosheet-like metasilicate catalytic materials were developed as heterogeneous catalysts towards styrene oxidation for the first time. Concurrently, the special heteroatom cobalt or magnesium-incorporated Ni-based nanosheet-like metasilicate were developed together via the proposed synthesis tactics. The resulted sheet-like nanomaterials were meticulously characterized and identified through valid techniques. The introduction of heteroatom metal elements of cobalt or magnesium incorporated in the Ni-based nanosheet-like metasilicate was proven to trigger the regulated catalytic effect including positive and negative aspects towards styrene oxidation, and their function was identified and understood based on the reaction exploration results, in which the present cobalt significantly give rise to the promotive catalytic conversion activity and selectivity towards styreneoxide(conversion 96.8%, selectivity 78.4%), while the magnesium oppositely induced the restraining catalytic capacity(conversion 72%, selectivity 51.3%) on the Ni-based metasilicate compared with pure one. The obtained heterogeneous Ni-based metasilicate retain durable catalytic activity during five recycling for styrene oxidation and inherit the regulated catalytic performance in the substrate expansion.Graphical abstractHerein, for the first time, Ni-based nanosheet-like 2-dimentional metasilicate containing cobalt or magnesium catalytic materials were constructed and proven to trigger the regulated catalytic effect towards styrene oxidation.Graphical abstract for this article
       
  • Systematic optimization of promoters in trace SnS2 coating SnO2
           nano-heterostructure for high performance Cr(VI) photoreduction
    • Abstract: Publication date: 31 March 2019Source: Applied Surface Science, Volume 471Author(s): Shuo Wang, Guangshe Li, Zhihua Leng, Yan Wang, Shaofan Fang, Jianghao Wang, Yanhua Wei, Liping Li Constructing heterojunction semiconductor materials with a strong interfacial interaction are emerging as a forefront strategy for promoting excellent photocatalytic performance. Herein, we report a novel SnS2/SnO2 heterojunction material via in-situ trace vulcanization strategy to coat SnS2 on the SnO2. The thickness of the coating layer can be regulated by controlling the content of SnS2. Moreover, molar ratio of S to Sn, particle size of SnO2 precursor, and vulcanization time that governs the SnS2 content of heterojunction catalyst were controlled to optimize photocatalytic performance. SnS2/SnO2 heterojunction catalyst with 19.5% SnS2 content delivered a ultrahigh visible-light activity in Cr(VI) degradation, remarkably superior to the inert SnO2 precursors and full-vulcanized SnS2 under identical testing conditions. The enhanced interfacial interaction can remarkably enhance the separation and transfer of photogenerated charges. The systematic methodology of interface regulation in SnS2/SnO2 system reported in this work would promote the understanding of nano-heterojunction material for high-performance water treatment application.Graphical abstractSnS2 is obtained from SnO2 in-situ transformed in the process of trace vulcanization. Strong interfacial interaction between SnO2 and SnS2 has promoted the separation of photoinduced electrons and holes effectively and provided more electrons to reduce the Cr(VI) to Cr(III).Graphical abstract for this article
       
  • Sustainable thermionic emission in CO2, helium and argon
           surroundings
    • Abstract: Publication date: 31 March 2019Source: Applied Surface Science, Volume 471Author(s): Gidon Ferdiman, Jacob Karni Thermionic materials are commonly used in high vacuum (
       
  • Atomic-Layer-Deposited ZrO2-Doped CeO2 Thin Film for Facilitating Oxygen
           Reduction Reaction in Solid Oxide Fuel Cell
    • Abstract: Publication date: Available online 15 December 2018Source: Applied Surface ScienceAuthor(s): Byung Chan Yang, Dohyun Go, Seongkook Oh, Jeong Woo Shin, Hyong June Kim, Jihwan An Ultra-thin ZrO2-doped CeO2 (ZDC) interlayers (20 nm thick) with varying doping ratios of 0, 20, and 60 mol% were prepared using atomic layer deposition (ALD), and were investigated as cathodic interlayers for low-temperature solid oxide fuel cells (LT-SOFCs). The inclusion of ZrO2 in CeO2 film induced the reduction of Ce4+ to Ce3+ with higher concentration of oxygen vacancies, and also enhanced the resistance of the film to the coarsening at elevated temperature (800 °C), well preserving the nanoscale fine grain structure. As a result, the maximum power density of the cell with 20 mol%-doped ZDC interlayer improved by 57 % compared to the cell without the interlayer due to enhanced activation process at the cathode, which seems to be due to higher oxygen vacancy population as well as higher grain boundary density at the electrolyte-cathode interfaceGraphical abstractGraphical abstract for this article
       
  • Synthesis and growth mechanism of carbon-supported nanoparticle catalysts
           by physical vapor deposition onto a liquid medium substrate
    • Abstract: Publication date: Available online 15 December 2018Source: Applied Surface ScienceAuthor(s): In Young Cha, Hyung Tae Kim, Minjeh Ahn, Jong Hyun Jang, Young Gyu Kim, Yung-Eun Sung, Sung Jong Yoo Metal nanoparticles (NPs) have been extensively investigated owing to their unique properties attributing to their high surface/bulk ratio and finite number of atoms. However, the thermodynamic instability of NPs, which originates from their finite size, limits their practical applications. Hence, carbon-supported Pt NPs are synthesized onto carbon-containing liquid substrates via direct one-step sputtering. In order to successfully produce uniform Pt NPs via sputtering using various ionic liquids as non-volatile liquid substrates, special conditions are required, and the relationship between ionic liquids and particle surfaces should be investigated. It has been reported that anions and carbon supports of ionic liquids significantly affect the dispersion and synthesis of Pt NPs. In this study, we proposed a mechanism underlying the chemical bonding between anions and carbon supports and verified it using X-ray photoelectron spectroscopy and infrared spectroscopy.Graphical abstractGraphical abstract for this article
       
  • Indium Tin Oxide Modified with Dendrimer-Encapsulated Pt Nanoparticles as
           Efficient p-Aminophenol Redox Cycling Platforms
    • Abstract: Publication date: Available online 15 December 2018Source: Applied Surface ScienceAuthor(s): Soon Bo Lee, Youngwon Ju, Yongwoon Lee, Joohoon Kim In this work, we studied indium tin oxides (ITOs) modified with dendrimer-encapsulated Pt nanoparticles (Pt DENs) to develop efficient p-aminophenol (p-AP) redox cycling platforms. The ITO surfaces were modified via electro-oxidative grafting of the terminal amine groups of the dendrimers encapsulating catalytic Pt nanoparticles (i.e., Pt DENs). Compared to conventional ITO surfaces, the Pt DEN-modified ITOs showed highly enhanced electrochemical oxidation current of p-AP even at low potentials with no significant background oxidation current due to the catalytic activity of Pt nanoparticles, leading to high signal-to-background ratio for sensitive p-AP redox cycling. The enhanced p-AP redox cycling on the Pt DEN-modified ITOs led to ∼17.8 times higher sensitivity of the p-AP redox cycling than that obtained with conventional ITOs. In addition, the Pt DEN-modified ITOs were found to be suitable as platforms for the immobilization of oligonucleotides due to the globular structure of dendrimers, which have a high surface-to-volume ratio and multiple terminal functional groups, grafted on ITO surfaces. The DEN-modified ITOs could be further functionalized by the immobilization of single-strand DNA oligonucleotides with high surface density (i.e., (2.2 ± 0.4) x 1012 molecules/cm2), which is ∼4.4-fold higher than that on the surface of conventional ITOs.Graphical abstractGraphical abstract for this article
       
  • Immediate release of helicid from nanoparticles produced by modified
           coaxial electrospraying
    • Abstract: Publication date: Available online 15 December 2018Source: Applied Surface ScienceAuthor(s): Deng-Guang Yu, Xiao-Lu Zheng, Yaoyao Yang, Xiao-Yan Li, Gareth R. Williams, Min Zhao In this paper, a modified coaxial electrospraying process was explored for the generation of novel nanoscale composite materials. A solution comprising 5% (w/v) of the model drug helicid and 10% (w/v) polyvinylpyrrolidone (PVP) K10 in a mixture of N,N-dimethylacetamide and ethanol (4:6, v:v) was employed as the shell working liquid. This could not be processed into a solid product when processed by single-fluid electrospraying. However, when undertaking co-axial electrospraying with a core shellac solution (40% w/v in ethanol) solid particles were obtained. An extremely thin nanocoating layer of drug-polymer composite with an estimated thickness of 7 nm was deposited on a shellac core. X-ray diffraction and infrared spectroscopy demonstrated that the drug was converted into an amorphous nanocomposite with the PVP in the shell layer, losing its original crystalline state. In vitro dissolution tests revealed that all the helicid loading could be released within one minute, suggesting the particles have potential applications to deliver very rapid therapeutic effects. Mechanisms are proposed underlying the formation and functional performance of the materials.Graphical abstractGraphical abstract for this article
       
  • Electrochemical and photoelectrochemical water oxidation of solvothermally
           synthesized Zr-doped α-Fe2O3 nanostructures
    • Abstract: Publication date: 31 March 2019Source: Applied Surface Science, Volume 471Author(s): B. Jansi Rani, M. Praveen Kumar, G. Ravi, S. Ravichandran, Ramesh K. Guduru, R. Yuvakkumar To investigate the oxygen evolution reaction of overall water-splitting process, Zr-doped α-Fe2O3 nanostructures were synthesized by employing one-pot solvothermal route. This work reported the electrochemical and photoelectrochemical (PEC) properties of synthesized photoanodes depending on solvothermal treatment time (i.e., 12, 16, and 20 h) maintained during synthesis. The treatment time influenced the morphology of Zr-doped α-Fe2O3 nanostructures, which directly exert an effect on the electrochemical and PEC performance of the synthesized photoanodes. The high conductivity and lowest Tafel slope value (83 mV/decade) were attained from electrochemical studies for the nanoflake morphology. The highest photocurrent of about 0.52 mA/cm2 at 1.5 V Vs RHE was obtained for Zr-doped α-Fe2O3 nanoflakes and 16.17% intrinsic photon conversion efficiency was achieved for the same sample with high photostability for 2 h under continuous irradiation of light. We reported the treatment time-dependent morphology effect on both electrochemical and PEC water oxidation of Zr-doped hematite nanoflakes in this work.
       
  • Highly stable and redox property-enabled tricopper dimolybdate
           nanostructures for electrochemical supercapacitors
    • Abstract: Publication date: 31 March 2019Source: Applied Surface Science, Volume 471Author(s): Goli Nagaraju, S. Chandra Sekhar, Bhimanaboina Ramulu, Jae Su Yu Recently, battery-type electrode materials, such as transition metal oxides/molybdates, have attracted extensive attention in the development of high-performance supercapacitors (SCs), owing to their rich redox chemistry, high theoretical capacity and superior electrochemical activity. Herein, we prepared battery-type redox behavior-enabled tricopper dimolybdate (Cu3Mo2O9) with versatile morphologies of nanoflakes (NFs) and nanoparticles (NPs) by a facile hydrothermal method for SCs. With different reactants, the shape of Cu3Mo2O9 was altered under constant growth conditions. The morphological and structural characteristics of the prepared samples were investigated by FE-SEM, XRD and XPS analyses. Moreover, the electrochemical properties of the Cu3Mo2O9 nanostructures were evaluated in 1 M KOH electrolyte. From these results, the Cu3Mo2O9 NF sample exhibited a high areal capacity of 29.6 μAh/cm2 at 1 mA/cm2 with good rate capability of 61.1% at 20 mA/cm2, which are higher compared to the NP sample. Furthermore, the capacity retention of 131.3% (after 2000 cycles) was observed without any capacity fading for the Cu3Mo2O9 NFs, indicating the great cycling durability of the material. Such remarkable durability of the Cu3Mo2O9 nanostructures could be served as an efficient electrode in energy storage devices.Graphical abstractGraphical abstract for this article
       
  • Improved laser induced damage thresholds of Ar ion implanted fused silica
           at different ion fluences
    • Abstract: Publication date: 31 March 2019Source: Applied Surface Science, Volume 471Author(s): Bo Li, Xia Xiang, Wei Liao, Shaobo Han, Jingxia Yu, Xiaolong Jiang, Haijun Wang, Muhammad Mushtaq, Xiaodong Yuan, Xiaotao Zu, Yongqing Fu In this work, effects of 10 keV argon ion implantation on laser-induced damage threshold (LIDT) of fused silica were systematically investigated with ion fluences ranged from 1 × 1016 ions/cm2 to 1 × 1018 ions/cm2. Results show that only when the ion fluence increases above 1 × 1017 ions/cm2, the surface roughness apparently increases due to the formation of argon bubbles in the surface of fused silica. The concentration of defects decreases with the increased fluences up to 1 × 1017 ions/cm2 but then increases further, especially for the oxygen deficient center (ODC) defect. Based on the nanoindentation test results, Ar ion implantation generates large compressive stress and strengthens the surface of fused silica by surface densification. With the increase of the Ar ion fluences, the LIDTs of the samples increase due to the increases in both surface compressive stress and defects annihilation. However, at higher ion fluences, the increase of the densities of defects and argon bubbles are identified as the key reasons for the decrease of the LIDTs. Therefore, Ar ion implantation can improve the LIDTs of fused silica at moderate fluences.Graphical abstractGraphical abstract for this article
       
  • Mesophase micelle-assisted electrodeposition and magnetisation behavior of
           meso-porous nickel films for efficient electrochemical energy and magnetic
           device applications
    • Abstract: Publication date: 31 March 2019Source: Applied Surface Science, Volume 471Author(s): Farzad Nasirpouri, Saeedeh Barzegar, Aleksei Yu. Samardak, Alexey V. Ognev, Alexander A. Zubkov, Alexandru Stancu, Alexander S. Samardak Mesoporous magnetic materials have found interesting potential applications in electrochemical energy harvesting and energy-efficient magnetic actuation device applications. Here we report on the electrodeposition and magnetic properties of mesoporous nickel films from lyotropic liquid crystal (LLC) templates formed by cetyltrimethylammoniumbromide (CTAB) cationic surfactant. Diffusion-controlled electrodeposition mechanism of nickel is determined. Films are electrodeposited under a constant current ranging from 1 to 7.5 mA cm−2 from an aqueous solution containing 0.1 M nickel sulphate, 0.2 M boric acid solution and CTAB with a concentration ranging from 0 to 50 wt.%. Mesopores develop an arranged hexagonal structure due to the micellar positional and orientational order reaching its highest value at 30 wt.% of CTAB at 2 mA cm−2. This is confirmed by transmission electron microscopy (TEM) and electrocatalytic surface area measurement. Electrodeposition current density and pH modify the mesoporous dimensions and therefore the magnetic properties change, tough hydrogen evolution as a side reaction influences the mesoporous structure. We observe an increased in-plane magnetic coercivity value to a maximum of 214 Oe for the mesoporous nickel film, which correlates with the increased interaction field. The widening of the coercivity distribution in first-order reversal curve (FORC) diagrams indicates that films with higher CTAB content have more inhomogeneous structure, which can lead to complex magnetization reversal mechanisms. The results of this study will help to exploit novel multifunctional magnetic and electrochemical energy materials and devices.Graphical abstractA schematic illustration of the formation of spherical and hexagonally arranged rod-like micelles at different concentrations of CTAB.Graphical abstract for this article
       
  • Manganese-doped CeO2 nanocubes as highly efficient catalysts for styrene
           epoxidation with TBHP
    • Abstract: Publication date: 31 March 2019Source: Applied Surface Science, Volume 471Author(s): Yong Zhang, Fengli Yang, Ruihua Gao, Wei-Lin Dai CeO2-based nanocubes doped with different contents of manganese were fabricated via hydrothermal method and were used as catalysts in the selective oxidation of styrene with tert-butyl hydroperoxide (TBHP). Several characterization instruments and methods were employed to study the structure, surface, composition, and reducibility of these nanocubes. It was found that Mn was doped into ceria lattice to form Ce-based solid solutions, leading to an enrichment of oxygen defects, an enhancement of specific surface area and reducibility of CeO2 nanocubes. It was also found that the amount of Mn is a vital factor affected the concentration of oxygen vacancies and surface Mn3+ percentage, determining the catalytic activity in the epoxidation of styrene. Ce0.96Mn0.04O2 showed the highest catalytic activity and excellent stability, which was chiefly owing to the highest content of surface Mn3+ ions and the enrichment of oxygen vacancies.Graphical abstractGraphical abstract for this article
       
  • Hybrid laser and vacuum process for rapid ultrahydrophobic
           Ti-6Al-4 V surface formation
    • Abstract: Publication date: 31 March 2019Source: Applied Surface Science, Volume 471Author(s): R. Jagdheesh, M. Diaz, S. Marimuthu, J.L. Ocaña A novel technique of post-vacuum processing the laser patterned surface was used for high speed fabrication of Ultrahydrophobic Ti6Al4V surface and the basics behind the transformation of surface chemistry is investigated in this paper. The wetting property of the laser patterned dual geometry structures transforms to ultrahydrophobic in 120 min of vacuum process without any chemical treatments to suppress the surface polarity. The surface recorded static contact angle of 180°, sliding angle less than 5, and exhibits bouncing and roll-off characteristic due to the presence of composite interface. The transformation of hydrophobic property establish a clear relationship between the vacuum process period and the improvement in static contact angle. The surface chemical analyses by XPS reveals that the amount of surface carbon content increases 2.3 times higher because of the adsorption of unstable organic molecules by vacuum process. The low partial pressure of the water molecules (120 min.) compared to those occurs at standard atmospheric pressure (days). The transformation of freshly laser processed Ti6Al4V hydrophilic surfaces into ultrahydrophobic surface is due to the development of carbonaceous layer over the laser patterned structures, which helps to sustain the Cassi-Baxter state.Graphical abstractGraphical abstract for this article
       
  • Growth, morphology and stability of Au in contact with the
           Bi2Se3(0 0 0 1) surface
    • Abstract: Publication date: 31 March 2019Source: Applied Surface Science, Volume 471Author(s): M. Fanetti, I. Mikulska, K. Ferfolja, P. Moras, P.M. Sheverdyaeva, M. Panighel, A. Lodi-Rizzini, I. Píš, S. Nappini, M. Valant, S. Gardonio We report a combined microscopy and spectroscopy study of Au deposited on the Bi2Se3(0001) single crystal surface. At room temperature Au forms islands, according to the Volmer–Weber growth mode. Upon annealing to 100 °C the Au deposits are not stable and assemble into larger and thicker islands. The topological surface state of Bi2Se3 is weakly affected by the presence of Au. Contrary to other metals, such as Ag or Cr, a strong chemical instability at the Au/Bi2Se3 interface is ruled out. Core level analysis highlights Bi diffusion toward the surface of Au islands, in agreement with previous findings, while chemical interaction between Au and atomic Se is limited at the interfacial region. For the investigated range of Au coverages, the Au/Bi2Se3 heterostructure is inert towards CO and CO2 exposure at low pressure (10−8 mbar) regime.
       
  • Graphene aerogel encapsulated Fe-Co oxide nanocubes derived from Prussian
           
    • Abstract: Publication date: 31 March 2019Source: Applied Surface Science, Volume 471Author(s): Jinxiao Shao, Jianhui Feng, Hu Zhou, Aihua Yuan Hybridizing metal oxides with three-dimensional graphene is highly desirable for improving the ability of lithium storage. Herein a general strategy was employed to fabricate nanocomposites containing heterometallic oxide and graphene aerogel (GA) for the first time, in which Prussian blue analogue (PBA) was selected as self-sacrificial template for the preparation of metal oxide. The Fe-Co oxide nanocubes in the composite were homogeneously encapsulated in the network of GA, and meanwhile acted spacers separating adjacent graphene sheets. The as-prepared self-standing Fe-Co oxide@GA composite was used directly as excellent integrated anode material of lithium-ion batteries. More importantly, the composite electrode delivered an outstanding cycle stability with a specific capacity of 947 mA h g−1 at 100 mA g−1 after 130 cycles. Such superior Li-ion storage ability originates from the hierarchically encapsulated architecture and the strong synergistic effect between metal oxide and GA. The interconnected network of GA significantly improves the conductivity of the whole electrode as well as provides the space for buffering volume change of metal oxides, whereas metal oxides strongly wrapped within graphene nanosheets contribute large specific capacity.Graphical abstractThe combination of graphene aerogel (GA) and PBA-derived oxide resulted in the formation of hereometallic oxide@GA for the first time, and the integrated anodes exhibited superior Li-ion storage properties.Graphical abstract for this article
       
  • Highly efficient capturing and adsorption of cesium and strontium ions
           from aqueous solution by porous organic cage: A combined experimental and
           theoretical study
    • Abstract: Publication date: 31 March 2019Source: Applied Surface Science, Volume 471Author(s): Zahra Ghalami, Vanik Ghoulipour, Alireza Khanchi In recent years, porous organic cages (POCs) have attracted considerable interests due to their nanoscale cavities and high surface area. In this study, the combined computational and experimental investigations were performed on POCs to examine their potential capabilities for the removal of Cs+ and Sr2+ ions from aqueous solution. CC3-R with interconnected tetrahedral pores is permeable to water. It has the ability to extract 1.86 mmol g−1 Cs+ (two ions per cage) and 2.77 mmol g−1 Sr2+ (three ions per cage) with distribution coefficients of 1.1 × 104 ml g−1 and 2.4 × 104 ml g−1, respectively. We have used computational methods to calculate the binding energies, strain energies and free energy perturbation (FEP). Effects of contact time and metal ion concentration on the removal of these ions, and extraction capacity of CC3-R for metal ions were examined in detail. Our simulation results are in reasonable agreement with the experimental reports. Thus, our simulation results plays an important role in the proper evaluation of solid phase extraction (SPE) with CC3-R cage.
       
  • Design of graphitic carbon nitride supported Ag–Cu2O composites with
           hierarchical structures for enhanced photocatalytic properties
    • Abstract: Publication date: 31 March 2019Source: Applied Surface Science, Volume 471Author(s): Qiaoyue Xi, Ge Gao, Manyu Jin, Yanqun Zhang, Hua Zhou, Cunqi Wu, Yongxia Zhao, Lidan Wang, Pengran Guo, Jingwei Xu A novel ternary photocatalytic nanocomposite, Ag–Cu2O/C3N4, has been successfully synthesized via a facile two-step reduction procedure at room temperature, wherein Ag nanoparticles are directly growing on the surface of Cu2O supported by C3N4 nanosheets. The resulting ternary Ag–Cu2O/C3N4 photocatalyst exhibits enhanced photocatalytic activity towards methyl orange (MO) degradation compared with its counterparts (Cu2O, spherical Ag–Cu2O and Cu2O/C3N4), demonstrating a removal rate of MO up to 95.7% within 30 min. The enhanced photocatalytic activity can be ascribed to the following factors: (1) the surface plasmon resonance effect of Ag nanoparticles broadening the visible light response of Cu2O; (2) the introduction of C3N4 functioning not only as a fast electron delivery but also a fine stabilizer to prevent the Ag–Cu2O composite from agglomeration. Mechanism studies reveal that MO is cracked into smaller fragments and the h+ is the main reactive species participating in the photocatalytic process. Moreover, the Ag–Cu2O/C3N4 photocatalyst also shows high photodegradation ability for another two representative azo dyes, acid orange II and congo red. This study demonstrates the potential of Ag–Cu2O/C3N4 in the degradation of azo dyes and also provides a guide to design of Cu2O-based ternary photocatalysts for further wastewater remediation.Graphical abstractGraphical abstract for this article
       
  • Critical insight on the hydrothermal effects toward exfoliation of g-C3N4
           and simultaneous in-situ deposition of carbon quantum dots
    • Abstract: Publication date: 31 March 2019Source: Applied Surface Science, Volume 471Author(s): Kien Tiek Wong, Seok Byum Jang, Pichiah Saravanan, In Wook Nah, Sehkyu Park, Jaeyoung Choi, Chulhwan Park, Younghun Kim, Yeomin Yoon, Min Jang In this study, exfoliated g-C3N4 (GCN) coupled carbon quantum dots (CNQDs) were prepared via one-pot hydrothermal (HT) treatment at various temperatures (100–200 °C) and in various amounts of time (0–20 h). Comprehensive characterization was conducted to study not only the chemical states, photo-optical properties, particle sizes, and crystal structures, but also the effect of these changes on the degradation of BPA. Photocatalytic degradation was conducted under near-visible LED as a low energy light source (0.128 W cm−3). The CNQD that were prepared at 180 °C for 12 h showed the highest degradation rate (3.6 × 10−2 min−1), which was 3.0 times higher than GCN. These improved photocatalytic activities corresponded to increases in the photo-reactive surface via exfoliation of GCN sheets, introduction of heteroatom oxygen onto GCN sheets, the addition of CQDs, and shortened bandgap. These characteristics allow for the effective transfer and separation of electrons. Nonetheless, the structural breakdown of the CNQD was observed when the HT time was longer than 12 h (180 °C). The defected sheets showed a detrimental effect towards photocatalytic degradation by trapping electrons, leading to shorter electron life times.Graphical abstractGraphical abstract for this article
       
  • Highly preferred orientation of Ga2O3 films sputtered on SiC substrates
           for deep UV photodetector application
    • Abstract: Publication date: 31 March 2019Source: Applied Surface Science, Volume 471Author(s): Meng-Qiu Li, Ni Yang, Gui-Gen Wang, Hua-Yu Zhang, Jie-Cai Han As a wide-bandgap semiconductor oxide material, Ga2O3 has great application prospects in various optoelectronic fields. At present, much attention has been paid to Ga2O3 deep ultraviolet (DUV) detectors, in which Ga2O3 films are often poor-quality poly-crystalline or expensive mono-crystalline. In this paper, Ga2O3 films with highly preferred orientation were deposited on hexagonal SiC (6H-SiC) substrate by magnetron sputtering, and the as-prepared Ga2O3 films were then annealed. The influences of sputtering and annealing parameters on Ga2O3 films were analyzed. Finally, DUV photo-detectors based on the as-obtained Ga2O3 films were fabricated. The experimental results show, when choosing optimal sputtering parameters (RF power: 120 W, gas pressure: 1.5 Pa, film thickness: 400 nm), the sputtered Ga2O3 films with (2¯01) highly preferred orientation after annealing at 800 °C, have good crystalline quality (FWHM = 0.108°) between single-crystal and polycrystal, showing good compromise between optoelectronic characteristics and preparation cost. The fabricated metal-semiconductor-metal (MSM) DUV photodetector operated at a bias voltage of 10 V can achieve excellent comprehensive photo-detection properties for 254 nm ultraviolet light: the responsivity, detectivity and quantum efficiency are high as 2.6 A/W, 1.6 × 1012 Jones and 1265%, respectively, along with short response time of 0.26 s.
       
  • Effect of porous silicon substrate on structural, mechanical and optical
           properties of MOCVD and ALD ruthenium oxide nanolayers
    • Abstract: Publication date: 31 March 2019Source: Applied Surface Science, Volume 471Author(s): Ievgen Brytavskyi, Kristína Hušeková, Valerii Myndrul, Mykola Pavlenko, Emerson Coy, Karol Zaleski, Dagmar Gregušová, Luis Yate, Valentyn Smyntyna, Igor Iatsunskyi Ruthenium oxide (RuO2) has received significant attention in recent years for its photocatalytic properties and photoelectrochemical (PEC) performance. In the present research, RuO2 nanolayers were grown on n-type porous silicon (PSi) by metal organic chemical vapor deposition (MOCVD) and atomic layer deposition (ALD). The morphology, mechanical and optical properties of produced nanostructures were studied by means of scanning electron microscopy (SEM), transmission electron microscopy (TEM), energy dispersive X-ray spectroscopy (EDX), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), micro-Raman spectroscopy, diffuse reflectance and photoluminescence (PL) spectroscopy. It was shown that that MOCVD gives non-uniform distribution of RuO2 along the pore and it is deposited mainly in the near-surface of PSi, while distribution of ruthenium obtained by ALD looks conformal over the entire pore. The mean size of RuO2 nanocrystallites and mechanical stresses were determined by TEM, XRD and Raman spectroscopy. It was demonstrated that samples obtained by ALD demonstrate a good crystallinity, while crystalline phase for samples produced by MOCVD improve with RuO2 layer thickness increasing. It was established the formation of hydrated RuO2 during ALD and MOCVD. It was shown that the samples produced by MOCVD have slightly higher electrical conductivity than ALD samples. The average value of energy gap (Eg) for samples prepared by MOCVD depended on the number of injections. RuO2 nanolayers quenched intrinsic PL from the PSi matrix. The correlation between structural, optical, and mechanical properties of samples produced by MOCVD and ALD was discussed.
       
  • Mn-doped SnS2 nanostructure as a potential efficiency CO catalyst: A
           first-principles study
    • Abstract: Publication date: 31 March 2019Source: Applied Surface Science, Volume 471Author(s): Mingyu Zhao, Rumeng Zhao, Wei Li, Tianxing Wang, Yaqiang Ma, Xianqi Dai The SnS2 is a new class of 2D materials with unique properties, which are still largely unexplored in the CO catalyst field. The modulation of electronic structures and chemical activities of the Mn atom substituted for S atom in SnS2 monolayer sheet is studied based on density functional theory. The electrons of doped Mn are introduced to the dangling bond of monovacancy SnS2 system, which can enhance the stability of Mn-Sn bond. The Mn-SnS2 monolayer sheet prefers good catalytic activity for the CO oxidation via the more favorable Langmuir-Hinshelwood mechanism with a two-step route to the Eley-Rideal or the latest report of termolecular Eley-Rideal mechanisms. In summary, we show first-principles evidence toward the realization of SnS2 based catalyst for CO catalytic oxidation which can facilitate the applications of SnS2 in the fields of catalysis and air pollution prevention.Graphical abstractThe Mn-SnS2 monolayer sheet shows good catalytic activity for the CO oxidation via the Langmuir-Hinshelwood mechanism with a two-step route.Graphical abstract for this article
       
  • S 2 2- +in+molybdenum+sulfide+catalysts+toward+sulfur-resistant+methanation&rft.title=Applied+Surface+Science&rft.issn=0169-4332&rft.date=&rft.volume=">Insight for the effect of bridging S 2 2- in molybdenum sulfide
           catalysts toward sulfur-resistant methanation
    • Abstract: Publication date: 31 March 2019Source: Applied Surface Science, Volume 471Author(s): Zijia Yin, Jun Zhao, Baowei Wang, Yan Xu, Zhenhua Li, Xinbin Ma Unsupported MoS2 catalysts were synthesized by a one-step hydrothermal method using ammonium heptamolybdate and thiourea at different temperatures ranging from 150 °C to 180 °C. With the decrease of hydrothermal temperature, the obtained MoS2 catalyst showed an increased sulfur-resistant methanation performance. The physical structure and chemical characteristics of the catalysts were analyzed by N2-physisorption, XRD, SEM, HRTEM, Elemental Analyzer, H2-TPR, XPS and Raman techniques. Combining the catalytic performance trend with the characterization analysis results, we found that the catalysts obtained at lower temperature contain more bridging S22- groups, that is beneficial for H2 dissociation and methanation reaction. We deduced that over-stoichiometric sulfur in the catalyst existed in the form of bridging S22- groups, which increased with the decrease of hydrothermal temperature. The finding that the positive role of the bridging S22- groups rather than the S vacancies in MoS2 catalyst is helpful for designing high efficient MoS2 catalysts not only for methanation but also for other hydrogenation reactions.Graphical abstractUnsupported MoS2 catalysts were obtained by hydrothermal method at various temperatures ranging from 150 °C to 180 °C. The catalysts obtained at lower temperature show better CO conversion since they have more bridging S22- groups that are beneficial for H2 dissociation and formation of SH group.Graphical abstract for this article
       
  • Atomic structure of Sr/Si(0 0 1)(1 × 2) surfaces prepared by
           Pulsed laser deposition
    • Abstract: Publication date: 31 March 2019Source: Applied Surface Science, Volume 471Author(s): Tjaša Parkelj Potočnik, Erik Zupanič, Wen-Yi Tong, Eric Bousquet, Daniel Diaz Fernandez, Gertjan Koster, Philippe Ghosez, Matjaž Spreitzer A buffer layer formed by depositing a ½ monolayer of Sr on Si(0 0 1) is known to passivate the Si surface, while its surface structure constitutes a suitable template for the integration of various functional oxides with the existing Si platform. We used Pulsed Laser Deposition (PLD) to prepare a Sr/Si(0 0 1)(1 × 2) surface and analysed it using in-situ Reflection High-Energy Diffraction (RHEED) in combination with low-temperature Scanning Tunneling Microscopy (STM). The STM images reveal an atomically ordered surface with terraces composed of one-dimensional (1D) chains running along perpendicular directions on neighbouring terraces. The 1D chains are separated by 0.78 nm and exhibit a low-amplitude corrugation with a period of 0.39 nm. The measured values agree well with the size of the (1 × 2) unit cell observed for similar MBE-grown surfaces, while the density of the surface defects is somewhat higher in the presented case. According to simulated STM images based on DFT calculations, two types of surface defects were identified and explored: arrays of Sr vacancies and Sr adatoms. These results show that PLD can offer precise control for the preparation of high-quality Sr-buffered Si(0 0 1) surfaces.Graphical abstractGraphical abstract for this article
       
  • The adsorption of a single water molecule on low-index C3S
           surfaces: A DFT approach
    • Abstract: Publication date: 31 March 2019Source: Applied Surface Science, Volume 471Author(s): Yue Zhang, Xinying Lu, Dongsheng Song, Songbai Liu The adsorption of water molecules on tricalcium silicate (C3S), which influences the initial hydration of C3S, is still unclear at the atomistic level. In the present paper, density functional theory is employed to depict the adsorption of a single water molecule on seven low-index M3-C3S surfaces. The calculations show that both molecular and dissociative adsorption can occur on the C3S surfaces and that the latter mode is preferential. All of the ionic O atoms on the C3S surfaces can adsorb the H atoms from dissociated water molecules, while only two-coordinated covalent O atoms on the surfaces can form OH chemical bonds. The electronic structures of the ionic and two-coordinated covalent O atoms in the first atomic layer of the C3S surfaces show similar charge density localization of the valence band maximum (VBM), which can describe the variations in the reactivity of the ionic O atoms in the bulk or exposed on the surface slab. The partial density of states (PDOS) analysis shows that the formation of new CaO bonds is mainly due to the overlap of O-2s and Ca-3p orbitals and O-2p and Ca-3d orbitals. Furthermore, the position of the OH group generated from the dissociated water molecule is found to significantly affect the adsorption energy. The general order of the adsorption energy in terms of the position of the OH group is Ehollow > Ebridge > Etop. The findings in this study provide additional support for the fundamental understanding of C3S hydration.Graphical abstractGraphical abstract for this article
       
  • Hybrid nanostructures of plasmonic gold nanoparticles with a-C:H thin
           films
    • Abstract: Publication date: 31 March 2019Source: Applied Surface Science, Volume 471Author(s): E.A. Konshina, D.P. Shcherbinin, M.M. Abboud, K.V. Bogdanov, I.A. Gladskikh, V.A. Polischuk Localized surface plasmon resonance (LSPR) of gold nanoparticles (Au NPs) in a granulated film with thickness 2 nm was investigated at the interface of two amorphous hydrogenated carbon (a-C:H) films with optical gap 0.67 eV and 2.7 eV. In these hybrid structures, a blue shift of the LSPR wavelength was observed in contrast with Au NPs on quartz surface at a room temperature. The annealing of such hybrid structures at 200 °C resulted in forming spheroid Au NPs with the dimensions about 11 nm which promotes increasing blue shift of the LSPR spectra. The intensity of the LSPR peak increased significantly after annealing at 300 °C, but Au NPs film morphology and LSPR peak position have not changed. After annealing at 400 °C the LSPR peak intensity in hybrid structure with a narrow gap a-C:H film decreased dramatically but did not change in the sample with a wide gap a-C:H. The observed changes in the LSPR spectra as a result of hybrid structures annealing are associated with the difference in the electronic and atomic structure of a-C:H thin films, as shown by their studies using Raman spectroscopy.Graphical abstractGraphical abstract for this article
       
  • Mechano-responsive colour change of laser-induced periodic surface
           structures
    • Abstract: Publication date: 31 March 2019Source: Applied Surface Science, Volume 471Author(s): Stephan Gräf, Clemens Kunz, Andreas Undisz, Robert Wonneberger, Markus Rettenmayr, Frank A. Müller A new concept of mechano-responsive colour-change is introduced in the present work that allows for turning flexible materials into an optical mechano-sensitive sensor. For this purpose diffraction gratings based on laser-induced periodic surface structures (LIPSS) are produced on ductile stainless steel surfaces (X2CrNiMo17–12–2) using a femtosecond laser (fs-laser). When the material is deformed, the increase of the lattice spacing in the diffraction grating leads to a mechano-responsive change of the initial structural colour in the direction of longer wavelengths. With increasing plastic deformation of the metal, the formation of tilted and twisted slip bands leads to a disappearance of the structural colours before the material fails. Using metal masters, the LIPSS can be transferred to elastomers by replica casting. For elastomers produced by replica casting, the mechano-responsive colour change is reversible. The mechanically induced colour change of LIPSS is of particular interest for the development of novel switches, safety devices, strain gauges, sensors, hazard classification and early detection of material failure.Graphical abstractGraphical abstract for this article
       
  • Numerical study of atomic scale deformation mechanisms of Ti grains with
           different crystallographic orientation subjected to scratch testing
    • Abstract: Publication date: 31 March 2019Source: Applied Surface Science, Volume 471Author(s): Andrey I. Dmitriev, Anton Yu. Nikonov, Artur R. Shugurov, Alexey V. Panin Atomic scale deformation mechanisms of Ti single- and bicrystals subjected to scratch testing were studied experimentally and using molecular dynamics simulation. The numerical model explicitly considers the crystallographic orientation of Ti crystallites experimentally determined from EBSD analysis. The stage character of the evolution of dislocation structure in the Ti crystallites under loading was revealed that resulted from fragmentation of the material in the scratch groove. When the direction of easy dislocation glide is close to the scratching direction, the stages of generation and movement of dislocations alternate with the stages of dislocation pinning. It was found experimentally that the initially softer grain was characterized by a shallower residual scratch depth than the originally harder one. MD simulation revealed that the fragmentation is an origin of the observed disagreement between the residual scratch depth and the initial hardness of Ti grains with different crystallographic orientations. Grain boundaries were shown not only to be barriers for dislocation glide but also to favor the development of rotational deformation and further fragmentation of the material in the scratch groove.Graphical abstractGraphical abstract for this article
       
  • Facile synthesis of high-surface vanadium nitride/vanadium
           sesquioxide/amorphous carbon composite with porous structures as electrode
           materials for high performance symmetric supercapacitors
    • Abstract: Publication date: Available online 12 December 2018Source: Applied Surface ScienceAuthor(s): Yifu Zhang, Xiaofei Wang, Jiqi Zheng, Tao Hu, Xin Liu, Changgong Meng Vanadium nitride/vanadium sesquioxide/amorphous carbon (denoted as VN/V2O3/C) composite is successfully synthesized by a facile hydrothermal method using ammonium metavanadate and glucose as the starting materials combined with a calcination process. Results show that VN/V2O3 nanoparticles (main VN and minor V2O3) are highly scattered on the amorphous carbon which is partly graphitized. VN/V2O3/C composite possesses the mesoporous structure with BET specific surface area of 134 m2·g−1, and the pore volume of 0.180 cm3·g−1. Electrochemical properties of VN/V2O3/C composite are investigated by cyclic voltammetry (CV), galvanostatic charge-discharge (GCD) and electrochemical impedance spectroscopy (ESI). VN/V2O3/C composite electrode exhibits the satisfied electrochemical properties with the specific capacitance of 169 F·g−1 at 5 mV·s−1 (138 F·g−1 at 0.5 A·g−1) and cycling behavior of 99.4% after 4000 cycles. Furthermore, VN/V2O3/C symmetric supercapacitor (denoted as VN/V2O3/C SSC) devices are assembled to assess their practical application. VN/V2O3/C SSC device exhibits the excellent electrochemical performance with the areal capacitance of 129 mF·cm−2 (16.2 F·g−1) at 5 mV·s−1 and 82 mF·cm−2 (10.3 F·g−1) at 0.5 mA·cm−2, cycling stability of 87% after 2000 cycles, and the energy density of 92 mWh·m−2 (1.55W·h·kg−1) at the power density of 2.25 W·m−2 (14 W·kg−1). The impressive finding in this work demonstrates that the VN/V2O3/C composite can be considered as a promising candidate for high-performance energy storage materials.Graphical abstractGraphical abstract for this article
       
  • Maskless formation of uniform subwavelength periodic surface structures by
           double temporally-delayed femtosecond laser beams
    • Abstract: Publication date: 31 March 2019Source: Applied Surface Science, Volume 471Author(s): Sohail A. Jalil, Jianjun Yang, Mohamed ElKabbash, Subhash C. Singh, Chunlei Guo Surface structures with nanoscale size and periodicity are important in controlling the flow of light as well as light-matter interaction. Fabrication of these periodic nanostructure requires sophisticated and expensive nanofabrication methods that limits large scale production of such structures. Laser induced periodic surface structures (LIPSS) is a scalable and cheap method to create periodic structures. However, they suffer from lacking a long-range order. Here, we present a maskless fabrication technique of creating highly uniform subwavelength structures on nickel surface, using two collinear femtosecond laser beams at various temporal delays. Our femtosecond laser induced periodic surface structures (FLIPSSs) show a high spatial uniformity with a grating period ranging between 320–350 nm. The high spatial uniformity is a consequence of using two pulsed beams with short inter-beam delay time due to reduction in the propagation length of excited surface plasmon polaritons (SPPs). The subwavelength period is due to grating splitting mechanism where the two beams sequentially interact with existing structures to create a superimposed grating. The demonstrated fabrication method enables large scale fabrication of regular sub-wavelength structures.
       
  • In-situ reactive loading of platinum onto tin oxide nanocrystals with
           superior catalytic performance for hydrogenation of 4-nitrophenol
    • Abstract: Publication date: 31 March 2019Source: Applied Surface Science, Volume 471Author(s): Shouliang Wu, Jun Liu, Yixing Ye, Zhenfei Tian, Pengfei Li, Yunyu Cai, Yue Lin, Changhao Liang Controlling the nucleation and growth process of noble metal on surface of catalyst supports is one of the most effective strategies to improve the catalytic performance of supported noble metal catalysts. In the present study, a novel and green route was developed to in-situ load platinum (Pt) onto tin oxide (SnO2) nanocrystals. Initially, nonstoichiometric SnOx colloidal nanoparticles (NPs) with high reactivity were facilely prepared by laser ablation of a metallic Sn target in deionized water. During the subsequent aging process, the PtCl42− ions react with these SnOx NPs, which gradually evolved into stoichiometric SnO2. The obtained ultrafine Pt NPs together with large amounts of Pt clusters and single atoms were uniformly dispersed on the surface of SnO2 nanocrystals. For hydrogenation of 4-nitrophenol (4-NP), these Pt/SnO2 nanocomposites (NCs) show a significantly higher value of mass-normalized rate constant (k/m, 0.557 s−1 mg−1) than that of most reported Pt-based catalysts, revealing remarkable catalytic activity. Also, no obvious deactivation was detected after seven successive cycles, indicating excellent catalytic stability of the Pt/SnO2 catalysts.Graphical abstractGraphical abstract for this article
       
  • Dynamics of double-pulse laser printing of copper microstructures
    • Abstract: Publication date: 31 March 2019Source: Applied Surface Science, Volume 471Author(s): Qingfeng Li, David Grojo, Anne-Patricia Alloncle, Philippe Delaporte Laser induced forward transfer process can be implemented in a double-pulse scheme where a solid thin film deposited on a transparent donor substrate is irradiated by two synchronized lasers. In a recently demonstrated methodology, a long pulse is first applied to melt the film and an appropriately delayed ultrashort laser pulse initiates material transfer in the liquid phase toward a receiver substrate. This provides a versatile method to print high-resolution (40 µm). In this paper we focus on the study of the dynamical aspects associated with these printing performances. The temperature evolution of the thin copper film during irradiation with a quasi-continuous wave (QCW) pulse is calculated. By combining the calculations with time-resolved imaging experiments, we reveal the influence of the copper film temperature and molten metal diameter on the ejection dynamics. Characterization of the transferred materials shows that the delay between the two laser pulses is a control parameter for the shape and volume of the printed structures. This is finally exploited to demonstrate high-precision printing of different debris-free microstructures onto a Si receiver substrate set as far as 60 µm away from the donor film.
       
  • PLD fabrication of oriented nanowires in magnetic field
    • Abstract: Publication date: 31 March 2019Source: Applied Surface Science, Volume 471Author(s): Ru.G. Nikov, A.Og. Dikovska, G.V. Avdeev, S. Amoruso, G. Ausanio, N.N. Nedyalkov This paper presents an experimental investigation on laser-assisted fabrication of oriented nanowires composed by magnetic nanoparticles. The nanowires were produced by implementation of pulsed laser deposition in presence of a magnetic field. The application of an external magnetic field led to the formation of nanowires with a length of several micrometers whose orientation is influenced by the direction of the magnetic field lines. The influence of the type of ambient gas and its pressure on morphology and phase composition of the deposited samples was investigated. It was found that the ambient gas has direct influence on both the degree of orientation and the phase composition of the nanowires. SEM analysis of samples deposited at different target-substrate distances showed that the density of the nanowires decreases with the increase of the distance. A preliminary result on the magnetic properties of the produced nanowires is also reported.Graphical abstractGraphical abstract for this article
       
  • High-performance, cost-effective permanent nanomagnet: Microstructural and
           magnetic properties of Fe-substituted SmCo nanofiber
    • Abstract: Publication date: 31 March 2019Source: Applied Surface Science, Volume 471Author(s): Jimin Lee, Tae-Yeon Hwang, Min Kyu Kang, Gyutae Lee, Hong-Baek Cho, Jongryoul Kim, Yong-Ho Choa We propose the substitution of some Co atoms in SmCo nanofibers with earth-abundant Fe as a means to prepare low-cost magnets with enhanced intrinsic magnetic properties compared to those of pure SmCo. To investigate the effect of Fe substitution upon microstructural and magnetic properties, we synthesized SmCoFe nanofibers (150–200 nm diameter) having various degrees of Fe substitution (0, 5, 10, 20, and 40 at%) via electrospinning and subsequent reduction using CaH2. All Fe-substituted samples showed an enhancement in (BH)max as compared to their non-substituted counterpart. Interestingly, substituting appropriate amount of Fe for Co enabled simultaneous increase of Ms, Hci and thus (BH)max of the SmCo nanofibers, resulting from an effective exchange-coupling effect: Superior Hci (about 7375 Oe) and a (BH)max (about 13.17 MG·Oe) over 153% that of non-substituted SmCo nanofibers were obtained in the 10 at% Fe-substituted sample. This work describes the synthesis of SmCoFe ternary magnetic nanofibers and elucidates the phase formation mechanism and the effect of Fe substitution in optimizing magnetic performance. This understanding can be extended to the synthesis of other SmCo phases having different chemical compositions and may enable access to a path far beyond the limitations of traditional magnetic materials.Graphical abstractGraphical abstract for this article
       
  • X-ray photoelectron spectroscopy analysis of the effect of photoresist
           passivation on InGaZnO thin-film transistors
    • Abstract: Publication date: 31 March 2019Source: Applied Surface Science, Volume 471Author(s): Peng Xiao, Junhua Huang, Ting Dong, Jian Yuan, Dong Yan, Jianing Xie, Haishu Tan Bottom-gate InGaZnO (IGZO) thin-film transistors (TFTs) with EOC photoresist (PR) passivation were fabricated. Compared to the unpassivated IGZO TFT with a mobility of 6.71 cm2 V−1 s−1, a hysteresis of 2.42 V and a poor bias stress stability, the PR-passivated IGZO TFT showed good electrical characteristics with a higher mobility of 8.85 cm2 V−1 s−1, a lower hysteresis of 0.06 V and a more reliable stability (△Vth = 0.36 V) under positive gate bias stress (PBS). The effect of PR passivation on the performance of IGZO-TFT was investigated by x-ray photoelectron spectroscopy (XPS), systemically. The result of XPS spectra of the O 1s core levels indicate that PR passivation effectively suppressed the adsorption/desorption effect on IGZO surface, resulting in fewer unstable states and higher electrical stability. Furthermore, XPS depth profile experiments show that the proportion of elements on the film surface changed and the IGZO surface was In-rich after PR passivation, enhancing the mobility. The PR passivation with low temperature (100 °C) process exhibited good dielectric quality and excellent barrier ability against water and oxygen molecules. Therefore, it may be a good candidate for high-mobility and high-stability flexible TFTs in future.
       
  • Influence of condensation enhancement effect on AFM image contrast
           inversion in hydrophilic nanocapillaries
    • Abstract: Publication date: 31 March 2019Source: Applied Surface Science, Volume 471Author(s): Ivan Mukhin, Mikhail Zhukov, Alexey Mozharov, Alexey Bolshakov, Alexander Golubok We found that enhanced vapor condensation in nanopores and nanochannels on hydrophilic surfaces affects contrast and spatial resolution of the atomic force microscopy (AFM) imaging. It was demonstrated, that at ambient conditions the use of conventional Si probes may provide contrast inversion of the topography image of the hydrophilic samples with nano-sized surface features whereas use of the probes modified with hydrophilic Pt/C nanowires ensures adequate AFM imaging. The phenomenon of the AFM contrast inversion and the spatial resolution improvement effect obtained with the probes modified with the nanowires are discussed. The explanation of the phenomenon considering the shape of liquid meniscus in hydrophilic nanopores and nanochannels is proposed.
       
  • Unravelling the adsorption disparity mechanism of heavy-metal ions on the
           biomass-derived hierarchically porous carbon
    • Abstract: Publication date: 31 March 2019Source: Applied Surface Science, Volume 471Author(s): Junting Sun, Meifen Li, Zhenhua Zhang, Junjie Guo Unravelling the adsorption mechanism is crucial in designing highly efficient adsorbent for removing heavy-metal ions from aqueous solution. In this paper, a biomass-derived hierarchically porous carbon (HPC) with oxygen- and nitrogen-containing functional groups has been adopted to investigate the adsorption equilibrium and mechanism towards heavy-metal ions (Cu (II), Zn (II), Pb (II), Cd (II), and Cr (III)). It indicates that the adsorption of heavy-metal ions on HPC all fit well with the Langmuir model, but present different adsorption capacity at the same condition. In addition, thermodynamic parameters including Gibbs free energy change and Enthalpy change of these adsorption processes also resemble the variation of the adsorption capacity, implying that the intrinsic characteristics of heavy-metal ions play critical role in the adsorption. Through analyzing the chemical state of the adsorbed heavy-metal ions on HPC, the first hydrolysis constant that is correlated with the hydrolyzing capability of the metal ions, are found to be responsible for the adsorption disparity of HPC towards the five heavy-metal ions since it decides the contact ratio of hydrolyzed heavy-metal ions with HPCs in aqueous solution. Therefore, this work is meaningful in providing a clear and detail insight into the adsorption disparity mechanism of porous carbon towards the removal of heavy-metal ions.Graphical abstractGraphical abstract for this article
       
  • Promoting effect of Ni on the structure and electronic properties of
           NixMo(1−x)S2 catalyst and benzene adsorption: A periodic DFT study
    • Abstract: Publication date: 31 March 2019Source: Applied Surface Science, Volume 471Author(s): Yibin Liu, Yu Dang, Xiang Feng, Xiaobo Chen, Chaohe Yang Aromatic hydrogenation (e.g., benzene) over MoS2-based catalyst harbours essential importance in hydrotreating process due to stringent environmental and fuel requirement. In this work, the promoting effect of Ni on structure and electronic properties of NixMo(1−x)S2(1 0 0) surface (x = 0, 0.25, 0.5, 1.0) and benzene adsorption has been investigated by DFT calculations using PW91-OBS and PW91 functions. It is found that the adsorption of benzene requires at least three coordinatively unsaturated sites (CUS), which can improve the activation of CC bond. The introduction of Ni facilitates the formation of stable CUS sites, and enhances the eletrophilicity of the Mo atoms for adsorption. Furthermore, the volcanic-shape relationship between Ni content and benzene adsorption ability is then established. With the increase of Ni percentage from 0 to 50%, the adsorption energy and electrons transferred from benzene molecules to the surface gradually increase due to the increased ligand effect for Mo atoms. However, overmuch Ni leads to the sharp decrease of benzene adsorption energy. Dispersion correction analysis indicate that the interplay between benzene and Ni is dominated by weak vdW interactions. The results reported herein are beneficial to the design of efficient NiMoS2 catalysts for hydrotreating.Graphical abstractGraphical abstract for this article
       
  • Covalently functionalized graphene towards molecular-level dispersed
           waterborne polyurethane nanocomposite with balanced comprehensive
           performance
    • Abstract: Publication date: 31 March 2019Source: Applied Surface Science, Volume 471Author(s): Peikun Zhang, Pingfan Xu, Haojun Fan, Zhe Sun, Jiating Wen Despite considerable advances, it remains imperative but challenging to develop high-performance waterborne polyurethane (WPU) which combines with robust mechanical, thermal and flame retardant properties. Considering its unique structure and properties, graphene has been reported as a potential alternative to ameliorate the integrate performance of polyurethane. However, one of the intractable handicaps is how to effectively disperse graphene and enhance its interfacial interaction towards polymer matrix. We herein demonstrate the fabrication of WPU composite by covalently conjugating with hydroxyl-functionalized graphene oxide (fGO), which was wrapped with P-N flame retardants, using an in situ polymerization strategy. Results indicated that a nanostructured WPU/graphene composite (WPU/fGO) with molecular-level uniformity was prepared. Compared with pure WPU, the peak heat release rate and total heat release were significantly reduced by 39.2% and 18.6%. The well dispersion, lamellae blocking effect of graphene nanosheets and the catalytic charring performance of P-N flame retardant were conductive to the improved fire safety. Moreover, WPU/fGO composite exhibited a 139% enhancement in tensile strength, while maintaining the superior elongation at break (high as 857.5%). Overall, this effective yet promising paradigm may provide an achievable solution toward developing graphene-based polymer nanocomposites simultaneously with high fire safety and well-balanced comprehensive performances.Graphical abstractGraphical abstract for this article
       
  • The role of sulfur in promoted growth of carbon nanotubes in chemical
           vapor deposition proposed through the characterizations on catalytic
           nanoparticles
    • Abstract: Publication date: 31 March 2019Source: Applied Surface Science, Volume 471Author(s): Shunsuke Suzuki, Shinsuke Mori We have investigated effects of sulfur addition as a promoter on the growth of carbon nanotube (CNT) and attempted to provide insights into the role of sulfur during CNT formation via catalyst characterization. CNTs were synthesized on a quartz substrate using sulfur in addition to conventional catalysts, cobalt-molybdenum co-catalyst, through chemical vapor deposition employing carbon monoxide as a carbon source. Sulfur powder was used as a sulfur source in this work. Some characterization approaches such as atomic force microscope, high-resolution transmission electron microscopy, time-of-flight secondary ion mass spectroscopy, X-ray photoluminescence spectroscopy and chemical equilibrium calculation were performed in order to investigate the role of sulfur in CNT synthesis. It was suggested that sulfur and catalytic metal formed sulfides particularly in the vicinity of surface, resulting in the acceleration of CNT growth probably due to the enhancement of atomic carbon diffusion.Graphical abstractGraphical abstract for this article
       
  • Mechanism of the catalytic oxidation of methane on Pt(1 1 1) surfaces
           in moist environment: A density functional theory study
    • Abstract: Publication date: 31 March 2019Source: Applied Surface Science, Volume 471Author(s): Ruirui Wang, Junjie Chen, Weilong Zhao, Jing Wen, Haixia Li, Linke Li, Jingyu Ran Density functional theory studies were carried out to gain mechanistic understanding of the catalytic oxidation of methane on Pt surfaces, especially in moist environment. Transition-state theory was used to estimate the energy barriers for each of the elementary reactions involved in the catalytic oxidation process. The optimal adsorption geometry and the corresponding chemisorption energy were determined for all the species involved in each elementary step to elucidate the energetics of the pathways for methane adsorption and oxidation on Pt surfaces. As a first step, the scope of this study is limited to a Pt(1 1 1) surface. The elementary steps involve the dissociative chemisorption of methane on the Pt(1 1 1) surface, dehydrogenation reactions of adsorbed CHx species, and oxidation reactions of adsorbed reactive intermediates by adsorbed O and OH species. Microscopic reaction pathways and corresponding transition-state structures were identified. The results indicated that the primary reaction pathway is CH4* → CH3* → CH2* → CH* → HCO* → HCOO* → CO2*. In moist environment, the primary reaction pathway is CH4* → CH3* → CH2* → CH* + OH* → CHOH* → CO* + OH* → COOH* → CO2*. The rate-determining step for the reaction pathway from methane to adsorbed carbon dioxide is the dissociative chemisorption of methane due to its relatively high energy barrier. The presence of water in reactants can promote the catalytic oxidation process.Graphical abstractGraphical abstract for this article
       
  • Covalent coupling of tuberculostatic agents and graphene oxide: A
           promising approach for enhancing and extending their antimicrobial
           applications
    • Abstract: Publication date: 31 March 2019Source: Applied Surface Science, Volume 471Author(s): Madalina Tudose, Elena Maria Anghel, Daniela C. Culita, Simona Somacescu, Jose Calderon-Moreno, Victorita Tecuceanu, Florea D. Dumitrascu, Olguta Dracea, Marcela Popa, Luminita Marutescu, Coralia Bleotu, Carmen Curutiu, Mariana C. Chifiriuc In this work, we present a simple, two-stage method for the preparation of new and efficient antimicrobial hybrid systems, based on isoniazid and pyrazine-2-carbohydrazide tuberculostatic agents covalently linked to graphene oxide. In the first step, the carboxyl groups of graphene oxide are activated by transforming them into the corresponding acid chloride groups, which, in the second step, will react with the amino groups of the two drugs. Pyrazine-2-carbohydrazide was obtained from pyrazinoic acid and hydrazine hydrate and was confirmed by nuclear magnetic resonance spectroscopy. The materials have been characterized by elemental analysis, infrared spectroscopy, Raman spectroscopy, scanning electron microscopy, and X-ray photoelectron spectroscopy.Their antimicrobial activity was tested on mycobacterial (Mycobacterium terrae), as well as on Gram-negative bacteria (Escherichia coli ATCC 25922, Pseudomonas aeruginosa ATCC 27853), Gram-positive bacteria (Staphylococcus aureus ATCC 6538, Staphylococcus aureus ATCC 25923) and fungal (Candida albicans ATCC 10231), in planktonic and biofilm growth state. The biocompatibility of the tested compounds was assessed in vitro by live-dead fluorescence staining and flow cytometry. The results of this study have shown that the functionalization of graphene oxide with isoniazid and pyrazine-2-carbohydrazide both enhanced the anti-mycobacterial activity of the respective drugs and extended their antimicrobial spectrum towards other microbial strains, in planktonic and biofilm growth state, showing a promising potential for mitigating the impact of antimicrobial resistance and the deleterious effects of microbial biofilms. At the active tuberculostatic concentrations, the tested compounds exhibit very low cytotoxicity and do not interfere with the cellular cycle of Hep-2 cells. The flow cytometry and live/dead fluorescence staining proved that the tested compounds exhibit a microbicidal effect through induction of cellular lesions, consecutive to membrane depolarization.Graphical abstractGraphical abstract for this article
       
  • Design of active bifunctional electrocatalysts using single atom doped
           transition metal dichalcogenides
    • Abstract: Publication date: 31 March 2019Source: Applied Surface Science, Volume 471Author(s): Jeemin Hwang, Seung Hyo Noh, Byungchan Han Single atom catalyst is designed to achieve high catalytic activity while extremely minimizing precious metal loadings for electrochemical energy conversion and storage applications. Using first-principles density functional theory calculations, we screen 48 combinations of single atom catalysts anchored at defective monolayer transition metal dichalcogenides (A1/TMD; A = Ni, Cu, Pd, Ag, Pt and Au; TM = Mo, W, Nb and Ta; D = S and Se). With established methodologies, we identify five best catalysts for each of oxygen reduction/evolution and hydrogen evolution reactions among the stable candidates. A scaling relation between the Gibb’s free energy for intermediates is figured out to understand the governing mechanism of single atom catalysts with varying transition metal dichalcogenides supports and to introduce key descriptor. Pt1/MoS2 is proposed as the best bifunctional catalyst for oxygen reduction/evolution reaction. In addition, Pt1/NbSe2 and Pt1/TaS2 are promising candidates for oxygen and hydrogen evolution reactions. Treating the support itself as an active site for hydrogen evolution reaction, Pd1/NbS2 and Pt1/NbS2 are proposed as potential bifunctional catalysts toward oxygen reduction and evolution reaction, respectively. Conceptual design principle via high-throughput screening of single atom catalyst is demonstrated as a great approach to determine active and durable bifunctional single atom catalysts.Graphical abstractGraphical abstract for this article
       
  • Effect of surfactants on the performance of 3D morphology W18O49 by
           solvothermal synthesis
    • Abstract: Publication date: 31 March 2019Source: Applied Surface Science, Volume 471Author(s): Zhihuan Zhao, Yu Bai, Wenwen Ning, Jimin Fan, Zhanyong Gu, Honghong Chang, Shu Yin Three-dimensional W18O49 nanostructures were synthesized by a solvothermal method using WCl6 as precursor and ethanol as solvent. The effects of surfactant on the crystalline phase and morphology of tungsten oxide were investigated. It was found that the photothermal conversion performance and the nanostructures were affected by the surfactant additives. The results of XRD, SEM, TEM, BET and XPS indicated that the addition of surfactant had no effect on the composition of the samples, while the morphology of the sample changed from the irregular massive structure to the uniform polygon, lamellar or nest structures. The results of DRS and heat resistance test showed that the film had excellent infrared shielding properties. The sample synthesized by the adding of cetyltrimethylammonium bromide (CTAB) surfactant showed only 34.04% transmittance in the infrared wavelength range, while the transmittance maintained at high level of 77.5% in the visible range. It reached to higher heat resistance of 6.5 °C under 1 h sunlight irradiation than other samples, the temperature change was only 41.7% of the blank test.Graphical abstractGraphical abstract for this article
       
  • Enhanced photoelectrochemical performance and stability of Si nanowire
           photocathode with deposition of hematite and carbon
    • Abstract: Publication date: 31 March 2019Source: Applied Surface Science, Volume 471Author(s): Yuqi Qu, Feng Li, Peng Zhang, Liping Zhao, Jing Liu, Xuefeng Song, Lian Gao Tremendous efforts have been dedicated to the development of transition metal and/or metal oxide surface coating materials to enhance the activity and stability of photoelectrodes. Nanostructured Si photoelectrodes have shown outstanding photoelectrochemical (PEC) performance due to their effective photon absorption and charge generation, separation, and mobility. While the chemical stability and surface reaction efficiency of Si photoelectrodes still need improvement before commercial application. Herein, we report the design and synthesis of a composite Si photoelectrode with a configuration of C/α-Fe2O3/Si nanowires, which presented a stable photoelectrochemical hydrogen production in neutral electrolyte. The p-Si nanowires were prepared by metal-assisted chemical etching for enhanced optical absorption and decorated with a mesoporous α-Fe2O3 thin film (∼80 nm) through pyrolysis of ferrocene. A thin carbon passivation layer (∼20 nm) was further deposited through ion sputtering further increasing the stability of the composite structure and low bias photocurrent. The role of α-Fe2O3 and carbon layer have been discussed. The composite photoelectrode shows a stable photocurrent of ∼−27 mA/cm2 in 2 h and an anodic onset potential shift of ∼0.33 V relative to the bare Si in the neutral solution.Graphical abstractGraphical abstract for this article
       
  • The peculiarities of structural and optical properties of HfO2-based films
           co-doped with silicon and erbium
    • Abstract: Publication date: 31 March 2019Source: Applied Surface Science, Volume 471Author(s): Larysa Khomenkova, Nadiia Korsunska, Christophe Labbé, Xavier Portier, Fabrice Gourbilleau The effect of deposition conditions and further annealing treatment on microstructure and optical properties of (Si,Er)-codoped HfO2 thin films is investigated. The films are grown on silicon substrates by RF magnetron co-sputtering of Si and erbium oxide pellets on a HfO2 target. As-deposited and annealed samples are examined by means of spectroscopic ellipsometry, Fourier transform infrared spectroscopy and photoluminescence method. It is demonstrated that the variation of RF power density allows monitoring the dopant content. An annealing of the samples at 800–1100 °C for 10–60 min in nitrogen atmosphere results in the phase separation and the formation of HfO2, SiO2 and pure silicon phases. The films annealed at 900–950 °C demonstrate the red luminescence that is ascribed to the carrier recombination in Si nanocrystals. Annealing at higher temperatures causes an enhancement of rare-earth luminescence under non-resonant excitation providing an additional argument toward the formation of silicon nanoclusters. The mechanism of the excitation of Er ions is found to be similar to that of Si-rich-SiO2 films doped with rare-earths. The Si nanocrystals are considered as the main sensitizer at visible excitation while the energy transfer from host defects dominates at ultraviolet-deep blue illumination.Graphical abstractGraphical abstract for this article
       
  • Optical transmission during mid-infrared femtosecond laser pulses ablation
           of fused silica
    • Abstract: Publication date: 31 March 2019Source: Applied Surface Science, Volume 471Author(s): Qingqing Liang, Yue Zhong, Zhengquan Fan, Hanhu Diao, Vytautas Jukna, Wanghua Chen, Aurélien Houard, Zhinan Zeng, Ruxin Li, Yi Liu We report on the optical transmission of near-infrared (1.8 μm) femtosecond laser pulses during multiple pulses laser ablation of fused silica surface. In addition to the previously reported ciliary white light phenomenon (Phys. Rev. Lett. 110, 097601 (2013)), two new optical transmission phenomena were observed for relatively low energy laser pulses. We systemically examined the damage morphologies of the ablation site as a function of laser pulse energy and laser shot number. Laser induced periodic surface structures (LIPSS) with different periods and orientations were observed for different pulse energy regimes. Comparison of the damage morphologies and the optical transmission reveals that the two new optical transmission phenomena origin from the refraction of the incident near-infrared pulses on the LIPSS covered damage surface followed by nonlinear propagation of the beamlets and even filamentation if the laser energy was high enough. We found that the interference of the neighboring white light emissions gives rise to radially orientated optical fringes. Based on this observation, we proposed another interpretation for the ciliary white light phenomenon.Graphical abstractGraphical abstract for this article
       
  • Mechanistic studies of the influence of halogen substituents on the
           corrosion inhibitive efficiency of selected imidazole molecules: A
           synergistic computational and experimental approach
    • Abstract: Publication date: 31 March 2019Source: Applied Surface Science, Volume 471Author(s): Ismail Abdulazeez, Aasem Zeino, Choon Wee Kee, Abdulaziz A. Al-Saadi, Mazen Khaled, Ming Wah Wong, Abdullah A. Al-Sunaidi Adsorption behavior and corrosion inhibition mechanism of imidazole and its C2-halogenated analogues (with the halogen atoms being Cl, Br or I) on Fe(1 0 0) surface were investigated by DFT periodic slab calculations and electrochemical techniques. DFT calculations revealed that C2-halogenated imidazoles adopt the tilted conformation on Fe surface with a significantly lengthened C–halogen bond and readily undergo facile dissociation at the halo-substitution with calculated adsorption energies −3.95, −3.76 and −3.48 eV for 2-I-Imz, 2-Br-Imz and 2-Cl-Imz, respectively. Electrochemical evaluations supported with surface characterization studies showed that the inhibitor molecules adsorb onto mild steel with 2-I-Imz having the highest inhibition efficiency of 83.5%. The trend of observed inhibition efficiencies correlates with adsorption energies and kinetic behavior predicted by the MD approach. The strength of adsorption in the order I > Br > Cl. The present study therefore provides a thorough mechanistic understanding of the role halogen substituents could play on the corrosion inhibitive performance of small organic systems.Graphical abstractGraphical abstract for this article
       
  • Solvent-free ionic nanofluids based on graphene oxide-silica hybrid as
           high-performance lubricating additive
    • Abstract: Publication date: 31 March 2019Source: Applied Surface Science, Volume 471Author(s): Yuexia Guo, Lihe Guo, Guitao Li, Ligang Zhang, Fuyan Zhao, Chao Wang, Ga Zhang Solvent-free ionic nanofluids (NFs) of graphene oxide-silica hybrid nanocores (GO@SiO2) were synthesized for the first time via functionalizing in succession the nanocores with a covalently charged corona and an ionically tethered oligomeric canopy. Being intrinsically one-component materials, GO@SiO2 NFs display a liquid-like behavior in the absence of any solvent and show excellent dispersion stability in polyethylene glycol (PEG) base oil. Adding even small amount of GO@SiO2 NFs improved dramatically the lubrication performance of PEG base oil. It was revealed that GO@SiO2 NFs played an important role in physicochemical actions on the friction interface. This work provided direct evidence that a protective tribofilm grew on the sliding surfaces when molecular species of GO@SiO2 NFs were fed continuously onto the contact zone. In particular, graphitized GO and SiO2 nanoparticles digested in the tribofilm enhanced its lubricity and robustness. It is expected that solvent-free ionic GO@SiO2 NFs open up new opportunities for developing advanced lubricating nanomaterials.Graphical abstractSolvent-free ionic GO@SiO2 nanofluids: promising lubricating additive.Graphical abstract for this article
       
  • Formation of oxides on CoCrMo surfaces at room temperature: An XPS study
    • Abstract: Publication date: 31 March 2019Source: Applied Surface Science, Volume 471Author(s): Ivana Jelovica Badovinac, Ivna Kavre Piltaver, Robert Peter, Iva Saric, Mladen Petravic We have studied the initial stages of oxide formation on CoCrMo surfaces, exposed to oxygen environment or bombarded by low-energy oxygen ions at room temperature (RT), using x-ray photoemission spectroscopy (XPS) around Co 2p, Cr 2p and Mo 3d core-levels. The results are compared with the oxidation of pure Co, Cr and Mo metals from the literature. While the oxidation of all three metals from CoCrMo in oxygen atmosphere follows the logarithmic growth kinetics, characteristic for the electric field driven migration of metal cations or oxygen anions, oxidation induced by low-energy oxygen ions follows the parabolic growth rate.Graphical abstractGraphical abstract for this article
       
  • Surface course in Rochow reaction: First-principle study
    • Abstract: Publication date: 31 March 2019Source: Applied Surface Science, Volume 471Author(s): Zhengwei Zhang, Qiang Wang The first-principle method is employed to study the Rochow reaction. The Cu atom stably adsorbs on the Si (1 1 1) surface. The CCl bond of CH3Cl was broken by the SiCu bond only when the two bonds vertically close together. The Cu adatom triggers Rochow reaction, and seriously is an initiator. The main catalysis ability comes from SiCH3 or SiCl bonds. The Rochow reaction contains two stages. The first one is that the Cu adatome triggers reaction. The second one is that the SiCH3 and SiCl bonds catalyze the CCl bond to break and to form new SiCH3 and SiCl bonds.
       
  • Dual doping of mesoporous carbon pillars with oxygen and sulfur as counter
           
    • Abstract: Publication date: 31 March 2019Source: Applied Surface Science, Volume 471Author(s): Mao-Sung Wu, Jia-Chiun Lin Pillar-like mesoporous carbon doped with oxygen and sulfur heteroatoms was obtained through thermal pyrolysis of a zinc-based metal-organic framework, Zn-BTC (BTC = 1,3,5-benzenetricarboxylic acid), followed by acid treatment and sulfurization. The pillar morphology remained after acid etching and sulfur doping, while the content of disordered carbon and the structural defects were significantly increased, resulting in an increase in the electroactive sites for catalyzing the iodide/triiodide ions. In addition, the incorporation of sulfur heteroatoms into carbon frameworks could cause the reduction of oxygen-doped carbon pillars, improving the apparent electrocatalytic activity. The cyclic voltammetry and electrochemical impedance spectroscopy showed that the oxygen and sulfur dual-doped (OS-doped) carbon electrode has better electrocatalytic performance than the single oxygen doped (O-doped) carbon electrode, probably owing to the sulfur doping in carbon matrix that offered abundant electroactive site for boosting the iodide/triiodide redox shuttle. Dye-sensitized solar cell employing OS-doped carbon exhibited power conversion efficiency of 10.2%, greater than that using Pt (9.4%), O-doped carbon (8.0%), and ZnO-doped carbon (7.7%).Graphical abstractGraphical abstract for this article
       
  • Adsorption properties of O2 on the unequal amounts of binary co-doped
           graphene by B/N and P/N: A density functional theory study
    • Abstract: Publication date: 31 March 2019Source: Applied Surface Science, Volume 471Author(s): Chaoling Han, Zhenqian Chen Graphene acts as an advanced substrate material, and it has been used as an electrode in fuel cells because it can efficiently adsorb oxygen molecules. In this study, density functional theory (DFT) calculation has been performed to exactly simulate the adsorption and dissociation of oxygen molecules on the XY3-co-doped graphene. The results show that the positively charged P and B atoms act as active sites for oxygen adsorption on the surface of graphene. In addition, PN3-G and NP3-G exhibit higher catalytic activity than the other samples because of the facile transfer of electrons from the highest occupied molecular orbital (HOMO) of O2 to the orbital above the Fermi level in the samples. More interestingly, excessive adsorption leads to the direct dissociation of oxygen molecules and making further dissociation difficult. In conclusion, the adsorption of oxygen molecules at the hollow sites on the PN3-G and NP3-G occurs via the formation of a triangular ring or transformation into O2− is proposed as the optimal strategy because these routes are thermodynamically favorable and the associated energy barrier is low. Furthermore, after dissociation, it was found that the oxygen atoms preferably approach the P atom. This work may be useful as a reference for future experimental studies to develop effective metal-free catalysts for fuel-cell cathodes.
       
  • Optoelectronic and photocatalytic properties of zinc sulfide nanowires
           synthesized by vapor-liquid-solid process
    • Abstract: Publication date: 31 March 2019Source: Applied Surface Science, Volume 471Author(s): Yu-Shuan Sue, Ko-Ying Pan, Da-Hua Wei Zinc sulfide (ZnS) is a wide band-gap semiconductor with excellent optoelectronic properties suitable for photo-sensing devices and photocatalysts. Herein, the ZnS nanowires (ZnS NWs) have been successfully synthesized using thermal evaporation based on vapor-liquid-solid (VLS) method. From the examinations of photosensing device under ultraviolet B (UVB) irradiation, the photocurrent gain (Pg), responsivity (Rλ), response time and recovery time are 0.572, 2.761 mW/cm2, 3.2 s and 3.6 s, respectively. As to photocatalytic activity for methylene blue (MB), the apparent rate coefficient (K) of ZnS NWs is 9.78 × 10−3 (min−1). Although ZnS NWs-based photodetector cannot be workable under ultraviolet A (UVA) irradiation, with referring to recent medical literatures, UVB radiation is the major environmental risk factor for developing human skin cancer, the most common cancer worldwide. Thus, the most important contribution in this work is that the ZnS NWs-based UVB radiation-oriented photodetector has been successfully demonstrated via a simple process.
       
  • Interaction between Cu and Cr coadsorption on MnS inclusions in low alloy
           steels
    • Abstract: Publication date: 31 March 2019Source: Applied Surface Science, Volume 471Author(s): Wenting Lv, Weichao Jin, Luchun Yan, Xiaolu Pang, Huisheng Yang, Kewei Gao Interaction between alloy elements Cu and Cr on MnS inclusions was studied by Scanning Transmission Electron Microscope (STEM)/X-ray energy-dispersive spectrometer (EDS) and the first principles calculation method. Assuming that the enrichments of Cu and Cr play a key role on pitting corrosion of low alloy steel, STEM/EDS were used to observe the enrichments of Cu and Cr on MnS inclusions in this study. The first-principles calculation, which is based on density functional theory was used to investigate the segregation behavior of Cu and Cr in the Fe matrix and the adsorption behavior of Cu and Cr on MnS surface. The atomic structures, electronic and energetic properties of clean and Cu or Cr adsorbed MnS surface were calculated. The results showed that both Cu and Cr tend to segregate on the Fe (1 1 0) surface rather than solid dissolved in the Fe bulk. MnS (1 0 0) is the most stable surface amongst the low-index surfaces, and H (hollow) is the most stable adsorption site for both Cu and Cr. Coadsorption of Cu and Cr on MnS (1 0 0) surface was also studied. The results showed that Cu and Cr promote the adsorption of each other on MnS (1 0 0) surface. However, this interaction is effective only within a certain distance between them. Overall, these findings will be helpful to understand the mechanism of pitting corrosion induced by MnS.Graphical abstractGraphical abstract for this article
       
  • Enhanced visible photocatalytic activity of tree-like ZnO/CuO
           nanostructure on Cu foam
    • Abstract: Publication date: 31 March 2019Source: Applied Surface Science, Volume 471Author(s): Fa Cao, Ting Wang, Xiaohong Ji Novel tree-like ZnO/CuO composite, composed of CuO nanowire trunks and ZnO nanorod branches, have been successfully synthesized on Cu foam substrate. Single-crystalline CuO nanowires and ZnO nanorods are obtained by thermal oxidation and hydrothermal processes, respectively. The morphological, crystal and optical properties of the as-prepared samples have been studied by field-emission scanning microscopy, X-ray diffractometer, transmission electron microscopy, and UV–vis spectrophotometer. The resultant tree-like ZnO/CuO composites on Cu foam show excellent photocatalytic activity with a rate constant of about 0.0073 min−1 in the photo-degradation of Rhodamine B (RhB) under visible light (λ > 420 nm). The Cu foam not only provides extra-large surface area for the growth of tree-like CuO/ZnO composites, but also acts as an effective frame to support the catalysts. Furthermore, tree-like ZnO/CuO composite catalysts show high recovery yield for the recycling during the degradation of organic pollutants. This work provides an insight view into the design and synthesis of composite photocatalyst effectively supported by a substrate.
       
  • Rapid Cr(VI) reduction in aqueous solution using a novel microwave-based
           treatment with MoS2-MnFe2O4 composite
    • Abstract: Publication date: 31 March 2019Source: Applied Surface Science, Volume 471Author(s): Yixiong Pang, Lingjun Kong, Diyun Chen, Gutha Yuvaraja Microwave-induced catalytic system has been widely used in oxidation of organic pollutants, but no report focuses on heavy metal reduction. To expand the application field of microwave-induced catalytic system, MoS2 decorated MnFe2O4 was synthesized by hydrothermal method and employed for the reduction of Cr(VI) in microwave-induced catalytic system. The morphologies, chemical compositions, and optical properties of the synthesized catalysts were investigated using SEM, XRD, FT-IR and XPS. The MoS2-MnFe2O4 samples exhibited significantly enhanced microwave-catalytic performance for Cr(VI) reduction compared to pristine MoS2 and MnFe2O4, among which, the MoS2-MnFe2O4 (10 wt%) sample was most suitable for Cr(VI) reduction in aqueous solution. 85.8% of Cr(VI) removal was obtained in 16 min in the present of MoS2-MnFe2O4. The effect of catalyst dosage, initial pH and microwave output on Cr(VI) reduction were investigated. Mechanism of Cr(VI) removal was investigated by radical quenching experiments. The enhanced microwave-catalytic activity of MoS2-MnFe2O4 may be owing to the fact that MoS2 can act as an electron acceptor to suppress the recombination of microwave-excited electron-holes. These results showed that microwave-induced catalytic reduction system is promising in Cr(VI) decontamination in aqueous solution.Graphical abstractGraphical abstract for this article
       
  • Preparation and characterization of surface grafting polymer of ZrO2
           membrane and ZrO2 powder
    • Abstract: Publication date: 31 March 2019Source: Applied Surface Science, Volume 471Author(s): Dan Li, Jie Yao, Bing Liu, Hao Sun, Sjack van Agtmaal, Chunhui Feng Asymmetric alumina support zirconia (ASZ) supported poly (vinyl acetate) (PVAc) membranes were prepared. Vinyltrimethoxysilane (VTMS) was selected as a silane coupling agent. Polymer layer was successfully prepared on VTMS silylated ASZ membrane by vinyl acetate free radical graft polymerization. The physicochemical characteristic of ZrO2 powders and ASZ membranes were evaluated by various analytical methods: XRD, SEM-EDS, BET, FTIR, TGA, AFM, and contact angle. The surface free energy (SFE) values of the modified membranes were determined by the Owens-Wendt method, the contact angle measurements of glycerol and water were also carried out. Surface roughness increase as graft percentage of free radical graft polymerization increase. However, the water contact angle results show that surface wettability has no definite dependence on surface roughness (AFM). The process of surface grafting was characterized by FTIR and TGA analytical techniques. The results have proved that the VTMS and PVAc chains were successfully grafted onto the ZrO2 surface. The main parameters affecting grafting percentage, namely reaction temperature, reaction time, and monomer concentrations, were investigated experimentally.Graphical abstractGraphical abstract for this article
       
  • Friction stir processing of dual certified 304/304L austenitic stainless
           steel for improved cavitation erosion resistance
    • Abstract: Publication date: 31 March 2019Source: Applied Surface Science, Volume 471Author(s): Xiujuan Jiang, Nicole Overman, Nathan Canfield, Kenneth Ross Cavitation erosion is known to be prevalent in equipment in hydraulic environments. Understanding cavitation erosion and improving the erosion resistance of commonly used materials is of interest for both scientific and economic reasons. In this study, friction stir processing was employed to modify commercial dual certified AISI 304/304L austenitic stainless steel plates. The cavitation erosion behavior of the processed plates was evaluated and compared to that of the unprocessed steel. A temperature control algorithm was employed to maintain a target tool temperature during the processing. The cross sections of the processed nuggets were evaluated using optical microscopy, scanning electron microscopy and Vickers hardness testing. Erosion testing by cavitation liquid jet was performed conforming to ASTM G134 on specimens cut out of the nuggets of the commercially unprocessed and the processed 304/304L steel. The tool temperature was found to affect the microstructure and the cavitation erosion behavior. Friction stir processed steel showed greater than 3× improvement in cavitation erosion resistance (defined as the reciprocal of the mass loss of a given material) than the unprocessed 304/304L. Surface erosion patterns and erosion rates were characterized and the mechanisms of material removal were discussed.Graphical abstractGraphical abstract for this article
       
  • Exfoliation of graphite as flexible SERS substrate with high dye
           adsorption capacity for Rhodamine 6G
    • Abstract: Publication date: 31 March 2019Source: Applied Surface Science, Volume 471Author(s): Nagaraju Sykam, Naidu Dhanpal Jayram, G. Mohan Rao Adsorption is one of the most important processes in wastewater treatment, especially for dye removal. In addition to adsorption, there must be a vigilant technique, such as Surface Enhanced Raman spectroscopy (SERS), for detection of low concentration of dye molecules to detect water foiling. Herein, we report a simple, low cost, rapid and efficient technique for the production of exfoliated graphite (EG) under microwave irradiation at 800 W in 1 min, as excellent adsorption material for Rhodamine 6G (R6G) dye. The effect of adsorption process parameters such as pH, contact time, isotherm models (Langmuir and Freundlich) and kinetic models (pseudo-first and pseudo-second-order) on dye removal under aqueous solutions, were investigated. The maximum adsorption capacity for R6G dye is 212.72 (±5.3) mg/g. Meanwhile compressing of EG, into a flexible graphite sheet (FGS) demonstrates responsive SERS for R6G molecules up to detection limit of 10−7 mol/L. However, with silver nanoparticle incorporation, the detection limit increases up to 10−12 mol/L. Performance of flexible sheet checked over a month by rubbing sheet through paper and cloth doesn’t have any impact on the synthesis of exfoliated graphite. Aging factor of the sheet also shows reproducible SERS spectra after a month. These are the highest reported values till today, for adsorption of R6G dye on Exfoliated graphite, with reasonable SERS detection.
       
  • Enhanced electrocatalytic performance for the oxidation of methanol by
           hierarchical NiS/Ni(OH)2@polypyrrole/graphene oxide nanosheets
    • Abstract: Publication date: 31 March 2019Source: Applied Surface Science, Volume 471Author(s): Hui Mao, Zhenqian Cao, Xi Guo, Meihong Liu, Dayin Sun, Zhijia Sun, Hao Ge, Yu Zhang, Xi-Ming Song Novel hierarchical nanostructures composed of two-dimensional inorganic NiS/Ni(OH)2 and organic polypyrrole/graphene oxide (PPy/GO) nanosheets are successfully prepared by a simple solvothermal method. Due to the coordination interaction between Ni2+ and -NH- segments in PPy chains, lamellar NiS/Ni(OH)2 with the average thickness less than 10 nm are well immobilized and uniformly distributed on the surface of PPy/GO nanosheets by an in-situ growth, and the obtained hierarchical NiS/Ni(OH)2@PPy/GO nanosheets exhibit the excellent electrocatalytic activity towards methanol oxidation reaction (MOR) due to synergistic effects of lamellar GO, conductive PPy, electrocatalytically active Ni(OH)2 and NiS, which may be further enhanced by the synergistic effect of the hierarchical nanostructures. Therefore, the hierarchical NiS/Ni(OH)2@PPy/GO nanosheets can act as good candidates with the excellent catalytic activity for the substitution of Pt to the electrooxidation of methanol in alkaline media and reveal a potential application to direct methanol fuel cells (DMFCs). The mechanism of MOR on the surface of NiS/Ni(OH)2@PPy/GO modified glassy carbon electrode (GCE) is also investigated in detail, where methanol is mainly oxidized on Ni(III) oxide surface through direct electrooxidation and Ni(III) is used as active surface for MOR.Graphical abstractNovel hierarchical nanostructures composed of two-dimensional inorganic NiS/Ni(OH)2 and organic polypyrrole/graphene oxide (PPy/GO) nanosheets were successfully prepared by a simple solvothermal method and presented the excellent electrocatalytic activity towards methanol oxidation reaction (MOR), which may be attributed to synergistic effects of lamellar GO, conductive PPy, electrocatalytically active Ni(OH)2 and NiS.Graphical abstract for this article
       
  • Controllable fabrication of metallic micro/nano hybrid structuring surface
           for antireflection by picosecond laser direct writing
    • Abstract: Publication date: 31 March 2019Source: Applied Surface Science, Volume 471Author(s): H.P. Wang, Y.C. Guan, H.Y. Zheng, M.H. Hong We investigate the effect of micro/nano hybrid structures in cemented tungsten carbide with a focus on optical absorption enhancement. Distinct micro/nano hybrid structures, including regular LIPSS, semi-continuous nano-bumps and nanoscale to microscale protrusions, were induced on WC-Co alloy by picosecond laser irradiation, and reflectance performances of these controllable hybrid structures were compared. We provide insight into mechanisms responsible for protrusion formation by associating hydrodynamic instabilities of molten materials during laser irradiation. Spectral reflectance measurement reveals significant reduction of optical reflectance at laser-treated surfaces in visible wavelength range. The laser induced hybrid structures on WC-Co alloy show potential applications for solar photo-thermal conversion. Investigations of morphology evolution and reflectance performance pave the way for functional surface design via surface structuring process.
       
  • Quantum size effect in exchange asymmetry of ultrathin ferromagnetic films
           studied with Spin Polarized Low Energy Electron Microscopy
    • Abstract: Publication date: 31 March 2019Source: Applied Surface Science, Volume 471Author(s): Ryszard Zdyb, Ernst Bauer The magnetic properties of ultrathin ferromagnetic films are studied by means of Spin Polarized Low Energy Electron Microscopy. Measurements of the onset of ferromagnetic order, distribution and shape of magnetic domains, magnetization direction and their change are now well established standards for this technique. Here, the asymmetry parameter has been determined as a function of film coverage and energy of the incident electron beam. It reveals oscillatory behavior which is usually described as due to the quantum size effect (QSE). We explore the origin of the characteristic features observed in the asymmetry curves and distinguish between the QSE oscillations and other phenomena influencing the shape of the asymmetry curves. As an example we discuss the asymmetry of ultrathin iron films grown on the W(1 1 0) surface.
       
  • Synthesis of 3D dahlia-like Co3O4 and its application in superhydrophobic
           and oil-water separation
    • Abstract: Publication date: 31 March 2019Source: Applied Surface Science, Volume 471Author(s): Chao Chen, Bo Wang, Hongtao Liu, Tianchi Chen, Huaqiu Zhang, Jianghao Qiao The synthesis of nanomaterial on porous materials and use of their porous structure for oil-water separation and oil absorption underwater at normal temperature and pressure are a very significant process, which has attracted wide attention. In this paper, dahlia-like Co3O4 nanoparticles was synthesized on the surface of porous nickel foam by hydrothermal reaction. After modification with heptadecafluoro-1,1,2,2-tetrahydro-decyl-1-trimethoxysilane (FAS-17), the as-prepared sample surface could obtain good oleophobicity and excellent superhydrophobicity with high contact angles and low sliding angles. Furthermore, the as-prepared superhydrophobic composite had low adhesion to water and light oil, and could be subjected to simple and effective oil-water separation (including three light oil and one heavy oil) at normal temperature and pressure. Due to the magnetic properties of nickel foam, underwater oil absorption experiment was carried out by magnetic traction, which could achieve a perfect oil absorption effect. In addition, the comprehensive use of unmodified and modified Co3O4/nickel foam at the end of tube can quickly and efficiently carry heavy oil (trichloromethane)-water separation and collection. Therefore, the as-prepared dahila-like Co3O4 on nickel foam not only has good application value in oil-water separation, but also has excellent potential in underwater oil absorption.
       
  • Effect of TaN intermediate layer on the back contact reaction of
           sputter-deposited Cu poor Cu2ZnSnS4 and Mo
    • Abstract: Publication date: 31 March 2019Source: Applied Surface Science, Volume 471Author(s): Siarhei Zhuk, Terence Kin Shun Wong, Elizaveta Tyukalova, Asim Guchhait, Debbie Hwee Leng Seng, Sudhiranjan Tripathy, Ten It Wong, Mohit Sharma, Henry Medina, Martial Duchamp, Lydia Helena Wong, Goutam Kumar Dalapati Ultrathin tantalum nitride (TaN) intermediate layers (IL) with thickness from 3 nm to 12 nm have been used to limit the undesirable interfacial reaction between molybdenum (Mo) and copper-zinc-tin-sulphide (CZTS). The morphology, chemical and structural properties of the samples were characterized by X-ray photoelectron spectroscopy (XPS), Raman spectroscopy, X-ray diffraction analysis, and scanning transmission electron microscopy (STEM). Time-of-flight secondary ion mass spectrometry (TOFSIMS), energy-dispersive X-ray spectroscopy (EDX), and electron energy loss spectroscopy (EELS) have been used for elemental analysis. Thin TaN IL shows chemical reactivity towards sulphur (S) vapor at 600 °C and the incorporation of S in TaN reduces the S concentration in Mo films at the sub-surface region and thus improves electrical conductivity of sulphurised Mo. The use of a non-stoichiometric quaternary compound CZTS target along with TaN IL enables to minimise thickness of MoS2 layer and reduce void formation at the Mo/CZTS interface. Furthermore, incorporation of TaN IL improves scratch hardness of CZTS/Mo films to soda-lime glass substrate.
       
  • Enhancement of NO catalytic oxidation on activated carbon at room
           temperature by nitric acid hydrothermal treatment
    • Abstract: Publication date: Available online 8 December 2018Source: Applied Surface ScienceAuthor(s): Fu-Tian You, Guang-Wei Yu, Zhen-Jiao Xing, Jie Li, Sheng-Yu Xie, Chun-Xing Li, Gang Wang, Hong-Yun Ren, Yin Wang The nitric acid hydrothermal treatment (NAHT) of activated carbon (AC) was performed to greatly improve its activity of NO catalytic oxidation (NOCO) at room temperature by simultaneously altering pore size and N-doping. The activity was increased from 30.6 % to 56.6 % with the optimal nitric acid amount of 1.6 mL. Under this condition, the catalyst exhibited a more than 400 h stability, which is promising for a continuous NO removal. Characterization including SEM, TEM, XRD, Raman spectroscopy, N2 adsorption/desorption, elemental analysis, H2-TPR, FT-IR, in-situ DRIFTS, and XPS revealed that micropore distribution in 0.6 ∼ 0.7 nm was increased and N-containing functionalities like pyridinic, pyrrolic and quaternary N were introduced to AC surface by NAHT, both of which contributed to the promotion of NOCO activity. The mechanism of NOCO by AC after NAHT was proposed, including the nanoreactor effect of micropores and NO adsorption controlled by surface basicity.Graphical abstractGraphical abstract for this article
       
  • Graphene layer formation in pinewood by nanosecond and picosecond laser
           irradiation
    • Abstract: Publication date: 31 March 2019Source: Applied Surface Science, Volume 471Author(s): Romualdas Trusovas, Karolis Ratautas, Gediminas Račiukaitis, Gediminas Niaura Potential applications of graphene-based materials in nanoscale electronic devices depends heavily on the versatility of synthesis and modification methods. The significant trend of graphene materials production is based on laser-induced synthesis. In this work, we investigate the laser-induced formation of graphene layers in pinewood by utilising near-infrared picosecond (10 ps) and nanosecond (10 ns) pulses. Effect of laser irradiation dose and pulse duration time on the quality of graphene materials was comparatively evaluated. Raman measurements showed the formation of high-quality few-layer graphene structures with I(2D)/I(G) and I(D)/I(G) ratios of 1.10 and 0.69, respectively, at the nanosecond-laser irradiation dose of 662 J cm−2. The average in-plane crystallite size estimated from the Raman data was found to be 31 nm. Sheet resistance measurements showed a correlation with Raman data and revealed a significant decrease in electric resistance for the ns-laser prepared sample with the highest I(2D)/I(G) ratio. To get insight into the graphene formation mechanism, we performed modelling of the pinewood surface temperature after the laser pulse irradiation. Higher surface temperatures reached and ablation process during picosecond laser irradiation disturb crystalline lattice structure forming lower-quality graphene platelets. We found that the nanosecond laser produces less defected graphene layers.Graphical abstractGraphical abstract for this article
       
  • Broad-range ultrafast all-optical red-shifting of EUV surface plasmons:
           Proof-of-principle and advanced surface nanotexturing in aluminum
    • Abstract: Publication date: 31 March 2019Source: Applied Surface Science, Volume 471Author(s): Sergey I. Kudryashov, Irina N. Saraeva, Andrey A. Rudenko, Andrey A. Ionin Using aluminum as an example, ultrafast sub-ablative broad-range (EUV-IR) spectral tuning of surface plasmon resonance in metals by IR femtosecond laser pulses was demonstrated by theoretical modeling of prompt surface optics for strongly photoexcited materials and of their surface plasmon-polariton (SPP) dispersion curves, as well as by experimental multi-shot laser imprinting of surface plasmon-polaritons as large-scale regular surface ripples with minimal sub-diffraction periods down to 200 nm. According to laser-pump self-reflection and charge emission experiments, the key issue in the prompt optical tuning (spectral red-shifting) of EUV surface plasmon resonance in aluminum by the IR laser pulses is related to ultrafast surface charging of its surface via intense electron emission during the laser pump pulse, depleting its surface electron density and simultaneously decreasing its surface/bulk plasma frequencies, at the corresponding negligible surface ablative etching.Graphical abstractGraphical abstract for this article
       
  • Surface and interface engineering of hierarchical photocatalysts
    • Abstract: Publication date: 31 March 2019Source: Applied Surface Science, Volume 471Author(s): Rongchen Shen, Chuanjia Jiang, Quanjun Xiang, Jun Xie, Xin Li In developing efficient heterogeneous photocatalysts, the design and fabrication of hierarchical semiconductors at the micro/nanometer scales have received much attention during the past decade due to their unique advantages in addressing the critical problems during photocatalysis. However, there are still many challenges in designing and constructing highly efficient hierarchical photocatalysts. Thus, in this review, we first systematically summarize and discusse the fundamentals and important interface engineering strategies of designing hierarchical photocatalysts, such as fabricating Z-Scheme heterojunctions, constructing Schottky-based heterojunctions, creating carbon-based heterojunctions and designing multicomponent heterojunctions. Then, especially, the different surface modification approaches of hierarchical porous photocatalysts, including loading cocatalysts, exposing the reactive facets, introducing defects/heteroatoms, adding photosensitizers, are highlighted. Finally, the major conclusions are made regarding this promising class of heterogeneous photocatalysts, and some perspectives are given on its future development. Through studying the important advances on this topic, it may pave a new avenue for fabricating highly effective hierarchical semiconductors for various applications in photocatalysis, electrocatalysis, thermal catalysis and other fields.Graphical abstractThe advantages, challenges, interface engineering strategies and surface modification approaches of hierarchical photocatalysts are systematically summarized and addressed.Graphical abstract for this article
       
  • Low temperature Zn-doped TiO2 as electron transport layer for 19%
           efficient planar perovskite solar cells
    • Abstract: Publication date: 31 March 2019Source: Applied Surface Science, Volume 471Author(s): Xiaotao Liu, Zhenhua Wu, Yiqiang Zhang, Christos Tsamis The properties of the perovskite solar cells (PSCs) are highly correlated with Fermi level, trap-state density and conductivity of inorganic electron transport layer. Metal elemental doping is an effective solution to largely improve the property of oxide semiconductor thin film. In this study, zinc dopant is successfully inserted into TiO2 crystal lattice using low-temperature solution-processed route. We find that Zn-doped TiO2 films possess less trap-state density and better conductivity, compared to undoped thin films, which contributes to the promotion of short circuit current. Ultraviolet photoelectron spectroscopy displays inserting Zn2+ into TiO2 compact layer can lift up TiO2′s Fermi level, which reasonably improved the carrier dissociation and transportation. Consequently, CH3NH3PbI3 PSCs based on 4.5% Zn-doped TiO2 has obtained 17.6% power conversion efficiency (PCE), which is nearly 27.5% higher than control device (13.8%). In addition, triple-cation mixed-halide PSCs based on 4.5% Zn-doped TiO2 has obtained a PCE of 19.04%, which is almost 13.7% higher than PCE of the device with undoped sample 16.75%. These findings offer a potential low-temperature doping method in TiO2 ETL for flexible high-performance PSCs.Graphical abstractGraphical abstract for this article
       
  • Facile synthesis of PtPd/SnO2 nanocatalysts with good
           photo-electrocatalytic property
    • Abstract: Publication date: 31 March 2019Source: Applied Surface Science, Volume 471Author(s): Bingqian Yang, Yawei Yu, Jianbo Zhang, Lefan Yuan, Jingyuan Qiao, Xiulan Hu PtPd/SnO2 nanocatalysts were synthesized by a simple one-step way of plasma technique in an aqueous solution of tin(II) chloride by using Pt and Pd metal wire as the electrode pair. PtPd/SnO2/GNs composite catalysts were prepared by an ultrasonic mixing PtPd/SnO2 with GNs (GNs, graphene nanosheets). The PtPd/SnO2/GNs composite catalysts exhibit a significantly enhanced electrocatalytic performance, cycling stability and CO-poisoning tolerance towards methanol oxidation both under acidic and alkaline condition, which attributed to the synergism of PtPd alloy and SnO2. What’s more, the current density of PtPd/SnO2/GNs composite catalyst was obviously improved under light illumination, with 10,029 mA mgPt−1 which was about 1.3 times higher than that without light illumination under alkaline condition. The novel one-step plasma technique could provide a useful approach for fabricating other highly efficient electrocatalysts.Graphical abstractGraphical abstract for this article
       
  • DFT study of the two dimensional metal–organic frameworks X 3(HITP)2 as
           the cathode electrocatalysts for fuel cell
    • Abstract: Publication date: 31 March 2019Source: Applied Surface Science, Volume 471Author(s): Xin Chen, Fanghua Sun, Fan Bai, Zhengfeng Xie The search for cheap, stable, and more active oxygen reduction reaction (ORR) catalysts is of great significance to proton exchange membrane fuel cells, and two-dimensional metal–organic frameworks with metal–nitrogen active sites are attracting increasing attention. The ORR mechanisms on X3(HITP)2 (X = Cr, Mn, Fe, Co, Rh, Os, Ir) catalysts are studied by density functional theory. All possible adsorption sites are explored, and the central metals rather than hydrogen or carbon atoms are demonstrated as the most favorable catalytic sites, completely different from the case of the well-known Ni3(HITP)2. The predicted ORR activities of X3(HITP)2 follow the order of Ir3(HITP)2, Rh3(HITP)2, Co3(HITP)2, Fe3(HITP)2, Os3(HITP)2, Cr3(HITP)2, and Mn3(HITP)2, during which the first two have the highest onset potential of 0.92 and 0.86 V, respectively. This result uncovers that the ORR behavior of X3(HITP)2 can be engineered by substituting the central metals. The linear relationships between the adsorption energies of O2, OOH, O and that of OH species illustrate that the adsorption strength of OH can be used as the activity descriptor for the current X3(HITP)2. Ir3(HITP)2 and Rh3(HITP)2 not only have good ORR activities and stabilities, but also have high anti-poison abilities to some impurity gases, as well as CH3OH molecule.Graphical abstractGraphical abstract for this article
       
  • Controlled synthesis of praseodymium oxide nanoparticles obtained by
           combustion route: Effect of calcination temperature and fuel to oxidizer
           ratio
    • Abstract: Publication date: 31 March 2019Source: Applied Surface Science, Volume 471Author(s): Bahaa M. Abu-Zied This investigation focuses on the employment of the solution combustion route for synthesis of praseodymium oxide nanoparticles. The fabrication was be carried out by using the solution combustion of a fuel (urea) and oxidizer (praseodymium nitrate) mixture. The influence of fuel/oxidizer ratio and the temperature of calcination on the phases formed, morphological changes and the crystallite size of Pr6O11 have been checked. Various characterization tools have been used for the identification of the thermal behaviour of the precursors, structure and morphology of the prepared Pr6O11 nanoparticles, which include TGA-DTA, XRD, FT-IR, XPS, SEM, and TEM. With respect to the effect of the fuel content, it was found that using F/O ratio ≥4.0 at 500 °C praseodymium carbonate starts to form at the expense of the oxide phase. These phase changes were, also, companied by a noticeable morphological modifications. On the other hand, it was shown that Pr6O11 can be obtained as a single phase upon calcining at temperatures ≥500 °C. The electrical conductivity of Pr6O11 nanoparticles synthesized at 400–700 °C has been investigated over a measuring temperature range of 200–400 °C. The obtained results have led to a better understanding of the factors influencing the electrical conductivity behaviour of Pr6O11 nanoparticles, viz. the availability of Pr3+/Pr4+ pairs and the crystallite size.Graphical abstractGraphical abstract for this article
       
  • Enhanced hydrogen sorption on Mg17Al12 alloy induced adding Li: A first
           principle study
    • Abstract: Publication date: 31 March 2019Source: Applied Surface Science, Volume 471Author(s): Hua Ning, Xingyu Zhou, Zhiqiang Lan, Jin Guo, Lili Zhao, Dan Huang The adsorption and dissociation properties of hydrogen on the Li-adsorbed and -substituted Mg17Al12 (1 0 0) surfaces are investigated by using the first principle calculations. Compared with the clean (1 0 0) surface, the adsorption energies of H and H2 on the Mg17Al12 (1 0 0) surfaces with a small amount of Li are evidently improved. Moreover, the barrier energy of H2 dissociation on the Li-adsorbed Mg17Al12 (1 0 0) system is notably reduced 0.51 eV. The catalytic effects of Li on the enhanced hydrogenation properties of the Mg17Al12 surfaces are discussed.Graphical abstractGraphical abstract for this article
       
  • High quality GaN buffer layer by isoelectronic doping and its application
           to 365 nm InGaN/AlGaN ultraviolet light-emitting diodes
    • Abstract: Publication date: 31 March 2019Source: Applied Surface Science, Volume 471Author(s): Shengjun Zhou, Haohao Xu, Hongpo Hu, Chengqun Gui, Sheng Liu The isoelectronic doping in semiconductors is an effective method for improving device performance. Here we have investigated effects of isoelectronically Al-doped GaN buffer layer on optical and electrical properties of 365 nm InGaN/AlGaN ultraviolet light-emitting diodes (UV LEDs) grown by metal-organic chemical vapor deposition (MOCVD) on patterned sapphire substrate. In situ reflectance measurements revealed that the transition time from three-dimensional (3D) grain to step-flow two-dimensional (2D) coalesced growth mode was extended in the isoelectronically Al-doped GaN buffer layer as compared to undoped GaN buffer layer. The improved crystal quality, in terms of threading dislocation reduction, of the isoelectronically Al-doped GaN buffer layer was determined by cross sectional transmission electron microscopy studies and showed that the screw-type threading dislocation density was reduced. The light output power of UV LED was enhanced by 7.6% by incorporating optimum isoelectronic Al doping concentration in GaN buffer layer.
       
  • Adsorption mechanism of typical oxygen, sulfur, and chlorine containing
           VOCs on TiO2 (0 0 1) surface: First principle calculations
    • Abstract: Publication date: 31 March 2019Source: Applied Surface Science, Volume 471Author(s): Asad Mahmood, Gansheng Shi, Xiaofeng Xie, Jing Sun The photocatalytic degradation of volatile organic compounds has been gaining much interest in recent years to solve the long-standing problem of indoor air pollution. For this purpose, anatase TiO2 and its derivatives are regarded as potential photocatalyst materials. Thus, we study the adsorption mechanism of selected volatile organic compounds such as formaldehyde, methyl chloride, and carbon disulfide on TiO2 (0 0 1) surface using first principle calculations to comprehend their surface interaction and catalytic degradation in depth. The study suggests that formaldehyde interacts with TiO2 (0 0 1) surface through chemical bonds that form a saddle-like structure exhibiting a high adsorption energy value (0.543 eV). It can be inferred that the fivefold coordinated Ti5c and twofold coordinated O2c atoms are the only adsorption sites on TiO2 (0 0 1) surface. However, significant variations are observed for chloride and sulfur containing groups. For instance, the methyl chloride and carbon disulfide physisorbed on the surface of TiO2 (0 0 1) without any chemical bond formation exhibits low adsorption energy values. The results are further confirmed by calculating the corresponding density of states, and electron density differences in all cases. This study provides a detailed investigation of various VOCs on the surface of TiO2 (0 0 1), which provides further insight into the construction of photocatalytic materials for the photodegradation of VOCs.Graphical abstractGraphical abstract for this article
       
  • Preparation of orthogonal physicochemical gradients on PDMS surface using
           microfluidic concentration gradient generator
    • Abstract: Publication date: 31 March 2019Source: Applied Surface Science, Volume 471Author(s): Bingpu Zhou, Yibo Gao, Jingxuan Tian, Rui Tong, Jinbo Wu, Weijia Wen Recently, surface with desirable gradients has been proved to be a powerful tool for diverse applications from biological systems and chemical analysis to material science. In this work, we demonstrate a versatile and universal approach to realize controllable physicochemical properties in orthogonal gradients on polydimethylsiloxane (PDMS) surface. Based on a novel microfluidics network, we can easily establish the concentration gradients within the microfluidic channel for surface polymerization or chemical deposition to realize the stable characteristic gradient on the PDMS substrate. The method was introduced to prepare surface with two-dimensional physical (roughness) gradients, or combinational physicochemical gradients to study the synergistic effect on interested phenomenon. As a proof of concept, the experimental results show that the as-prepared substrate can effectively influence in various fields, such as protein adsorption and nano-particle immobilization, which can potentially be used for future systematical study in biological systems or practical applications in bio/chemical analysis/sensing.
       
  • Straightening single-walled carbon nanotubes by helically wrapped
           poly(9,9-dioctylfluorene) chains
    • Abstract: Publication date: 31 March 2019Source: Applied Surface Science, Volume 471Author(s): Xiao-Shuai Guo, Tian-Yu Zhang, Rui-Yang Wang, Jun-Ting Xu, Zhi-Qiang Fan In the present work, we found that single-walled carbon nanotubes (SWCNTs) could be straightened by poly(9,9-dioctylfluorene) (PFO) chains with both α- and β-conformations in different solvents. UV–vis and PL spectroscopic studies confirm that there exists π-π interaction between SWCNTs and PFO. SWCNTs are helically wrapped by the adsorbed PFO chains, which is different from the coaxial interaction between SWCNTs and poly(3-hexylthiophene) (P3HT). More stretched PFO β-conformers have a stronger interaction with SWCNTs, and the interactions between SWCNTs and PFO slightly improve the conjugation length of β-conformers in turn. We proposed that the straightening of SWCNTs by adsorbed rigid conjugated polymers is irrespective of interaction mode between them.Graphical abstractGraphical abstract for this article
       
  • A facile method for direct bonding of single-crystalline SiC to Si, SiO2,
           and glass using VUV irradiation
    • Abstract: Publication date: 31 March 2019Source: Applied Surface Science, Volume 471Author(s): Chenxi Wang, Jikai Xu, Shu Guo, Qiushi Kang, Yuan Wang, Yiping Wang, Yanhong Tian Single-crystalline silicon carbide is an attractive material for power electronics. However, it is difficult to achieve the direct bonding of SiC to conventional Si-based materials (e.g., Si, SiO2, and glass) due to the large mismatch in coefficients of thermal expansion and lattice constants. To solve the bottleneck, we present a facile direct bonding method using vacuum ultraviolet (VUV) surface irradiation for a robust combination of SiC to Si, SiO2, and glass at low temperatures (≤200 °C). The mechanisms behind the VUV-irradiated bonding of SiC to Si-based materials were also investigated. According to surface characterizations, VUV irradiation can lead to smooth and hydrophilic surfaces, which are beneficial for direct bonding in humid air. The tight and defect-free SiC/Si, SiC/SiO2 and SiC/glass bonding interfaces were confirmed by transmission electron microscopy. In particular, the enriched carbon transition layers were formed on the side of silicon carbide because of the oxidation and sputtering of Si atoms during VUV irradiation. This will possibly improve the bonding interfaces and contribute to the enhanced bonding strengths. Moreover, the SiC/glass bonded pair exhibited relatively high optical transparency in the UV–Vis range. Therefore, the direct bonding of single-crystalline SiC and heterostructure Si-based materials offers great potentials for high-performance power electronics, as well as micro/nanofluidic devices.Graphical abstractSingle-crystalline SiC was directly bonded to Si, SiO2, and glass substrates with robust and defect-free bonding interfaces.Graphical abstract for this article
       
  • Electric field induced two-dimensional electron gas and magnetism in
           LaFeO3/SrTiO3 (0 0 1) heterostructures
    • Abstract: Publication date: 31 March 2019Source: Applied Surface Science, Volume 471Author(s): Lili Li, Guangbiao Zhang, Jingyu Li, Dong Chen, Zhenxiang Cheng, Yuanxu Wang Perovskite oxide interfaces have become a platform for the realization of many unexpected physical properties in recent years, while effective electric control of magnetism is promising for future spintronic devices. In this work, external electric field is applied to control the physical properties of LaFeO3/SrTiO3 perovskite oxide heterostructures investigated by first-principles calculations based on density functional theory (DFT). We find that external electric field can effectively modulate the band dispersion around the Fermi level of both the n-type and the p-type interfaces. Negative electric field can weaken the band shift, even leading to a two-dimensional electron gas, which is accompanied by a reversible insulator-to-metal/half-metal transition at the n-type interface. Moreover, the n-type interface perfectly realizes a transformation from G-type antiferromagnetic to ferrimagnetic at −0.3 V/Å. Meanwhile, the electric field also regulates the electronic structure of the p-type interface of the heterostructure. Our work mainly focus on using electric field to tune the interfacial electronic structure and magnetic properties of perovskite oxides heterostructures, and further pave the way to the experimental design of novel magnetoelectric interface materials.
       
  • Electrooxidation of formic acid enhanced by surfactant-free palladium
           nanocubes on surface modified graphene catalyst
    • Abstract: Publication date: 31 March 2019Source: Applied Surface Science, Volume 471Author(s): Pacharapon Kankla, Jumras Limtrakul, Malcolm L.H. Green, Narong Chanlek, Patraporn Luksirikul Direct Formic Acid Fuel Cells (DFAFCs) have been extensively focused and rapidly growing as one of alternative energy systems for portable devices and automobiles. However, power energy requires the active and selective metal nanocatalysts to perform the highest electrochemical activity. Here, we propose a nanocubic shape of palladium nanoparticles (PdNPs) decorated on functionalized graphene (fG), where surface modification is obtained by surfactant free method. The 11 nm and high dispersion of Pd nanocubes (PdNCs), which are majorly enclosed with (1 0 0) indicated by XRD and HRTEM results, are successfully deposited on functionalized graphene (PdNCs/fG) and used as an enhanced electrocatalysts for formic acid oxidation. Our PdNCs/fG catalyst displays a remarkable mass activity towards formic acid oxidation (494.50 A/g, over 100 times) compared to commercial catalysts of Pd/C, and over 20 times to PdNPs on unmodified graphene or reduced graphene oxide (PdNPs/rGO). Moreover, our catalyst exhibits better stability and higher CO resistance. The PdNCs/fG catalyst also generates the superior specific activity towards formic acid oxidation to 20.37 A/m2. The study demonstrates the synergistic effect of high selective site enabled by {1 0 0} facet on PdNCs and a great potential from a support of modified graphene to Pd metal catalyst for the development of electrocatalysts in fuel cell applications.Graphical abstractGraphical abstract for this article
       
  • Preparation of molecularly imprinted PDMS elastomer for selective
           detection of folic acid in orange juice
    • Abstract: Publication date: 31 March 2019Source: Applied Surface Science, Volume 471Author(s): Adem Zengin, M. Utku Badak, Mustafa Bilici, Zekiye Suludere, Nahit Aktas Herein, it is reported an effective method to prepare novel molecularly imprinted polymers (MIP) on poly(dimethylsiloxane) (PDMS) elastomer via a combination of non-covalent imprinting approach and surface initiated reversible addition fragmentation chain transfer (SI-RAFT) polymerization for sensitive and selective detection of folic acid (FA). For this purpose, 2-(2-Methoxyethoxy) ethyl methacrylate (MEOMA), ethylene glycol dimethacrylate (EGDMA), azobisisobutyronitrile (AIBN), FA and dimethylsulfoxide (DMSO) were used as functional monomer, cross-linker, initiator, template molecule, and porogen, respectively. The adsorption behavior followed the Scatchard equation between FA and PDMS-MIP with a saturation adsorption capacity of 4.51 mg/g and pseudo-second-order kinetics with 60 min equilibrium adsorption time. Furthermore, PDMS-MIP elastomer was successfully applied for selective extraction and detection of FA from orange juice with sufficient recovery (95.5–100.5%) and relative standard deviation less than 7.0%. The limit of detection (LOD) for FA was found to be 0.0031 µg/mL with a linear range between 0.01 and 100 µg/mL and a correlation coefficient of 0.9997. Results showed the proposed method could easily, efficiently and selectively extracted FA from complex media. Note that this novel proposed method will open a new way to detect any selected molecules such as pesticide, protein, drug, etc. using molecularly imprinted PDMS elastomer materials.Graphical abstractGraphical abstract for this article
       
  • Two-dimensional CdS/g-C6N6 heterostructure used for visible light
           photocatalysis
    • Abstract: Publication date: 31 March 2019Source: Applied Surface Science, Volume 471Author(s): Guangzhao Wang, Xiaojiang Long, Kezhen Qi, Suihu Dang, Mingmin Zhong, Shuyuan Xiao, Tingwei Zhou We have calculated and discussed the electronic and optical properties of two-dimensional (2D) CdS/g-C6N6 heterostructures by using hybrid density functional of HSE06. The CdS and g-C6N6 can form CdS/g-C6N6 heterostructures through weak van der Waals (vdW) interactions. The CdS/g-C6N6 composites are indirect bandgap semiconductors and type-II heterostructures. The visible light absorbtion of CdS/g-C6N6 composites is obviously improved, and the band alignment is beneficial for spontaneous water redox reactions. Furthermore, the electrons migrating from CdS layer to g-C6N6 leads to the built-in electric field formation, which promotes the effective separation of photogenerated carriers. These factors imply CdS/g-C6N6 composites are promising visible light water-splitting photocatalysts.
       
  • Insights into the origin of super-high oxygen evolution potential of Cu
           doped SnO2 anodes: A theoretical study
    • Abstract: Publication date: 31 March 2019Source: Applied Surface Science, Volume 471Author(s): Aqing Chen, Shengjian Xia, Zhenguo Ji, Hongwei Lu SnO2 based anodes have been recognized as the most promising anodes for wastewater treatment due to the high oxygen evolution potential, high current efficiency and low cost. Herein, using large-scale screening-based density functional theory, we systemically investigate the origin of super-high oxygen evolution potential of Cu doped SnO2 anodes. We find that the low binding energy of OH* on (1 1 0) plane of Cu doped SnO2 anodes leads to the high onset potential for oxygen evolution. Detailed calculations of bond configurations and valence electron numbers reveal that the weak chemical absorption of OH* contribute to the low binding energy. The theoretical onset potential of oxygen evolution of 2.639 V (vs RHE) obtained from Free-energy diagram for OERs agrees well with the experimental value of ∼2.7 V (vs RHE).
       
  • MoSe2/graphite composite with excellent hydrogen evolution reaction
           performance fabricated by rapid selenization method
    • Abstract: Publication date: 31 March 2019Source: Applied Surface Science, Volume 471Author(s): Xu Mao, Jianpeng Zou, Danni Li, Guangyao Zhao, Zhengqi Song MoSe2/graphite composite was fabricated by rapid selenization method for the hydrogen evolution reaction (HER) application. The microstructure, surface composition and HER performance of MoSe2/graphite composite were evaluated by scanning electron microscopy, Raman spectroscopy, X-ray photoelectron spectroscopy and linear sweep voltammetry. The results indicate that the internal and external surface of graphite substrate is covered with MoSe2 nanosheets. The size, number and crystallinity of MoSe2 nanosheets can be controlled by adjusting the selenization parameters to achieve better HER activity of the electrodes. MoSe2/graphite composite prepared at 500 °C for 15 min exhibits the best HER activity and great stability in acidic solution with an over potential of −125.8 mV vs reversible hydrogen electrode (RHE) at the cathodic current density of 10 mA cm−2. The Tafel slope of MoSe2/graphite electrodes is 52.1 mV dec−1, which shows the best performance among the reported literatures of MoSe2 materials.Graphical abstractGraphical abstract for this article
       
  • Hexagonal boron phosphide as a potential anode nominee for alkali-based
           batteries: A multi-flavor DFT study
    • Abstract: Publication date: 31 March 2019Source: Applied Surface Science, Volume 471Author(s): Saif Ullah, Pablo A. Denis, Fernando Sato The adsorption of alkali atoms (Li, Na, and K) on graphene and hexagonal boron phosphide (h-BP) is studied by means of various density functionals including semi-local GGA, dispersion corrected DFT-D, meta-GGA, and many of the available non-local vdW-DF functionals. The accurate interaction energies are crucial for energy storage and battery applications as it is directly related to key properties in electrochemistry, such as storage capacities in general, and open circuit voltages (OCVs), in particular. A wider range of adsorption strength is predicted depending on the choice of non-local vdW-DF functionals. Furthermore, the performance of vdW-DF functionals was found to be independent of the choice of pseudopotentials used and especially if the choice is revPBE. Additionally, an excellent agreement is found between the Gaussian, VASP, and QE codes. Moreover, the h-BP is found to be an exceptional anode material for alkali batteries which can compete with any other available anode material. The small change in the adsorption energies as a function of increasing concentration of alkali atoms is a unique characteristic of h-BP. The exceptional 1283 mAh/g storage capacity not only for Li but in contrary with the previous study, also for Na in addition to the 642 mAh/g for K at vdW-DF/DZP level makes it a prominent candidate to be used as anode material. The average open circuit voltage for Li, Na, and K was also found to be in superb range. However, the values are found to be sensitive to the choice of functional, and in some cases, the storage capacity can be predicted as high as twice of the actual values. Therefore, the accurate description of the interaction is crucial and this study can be used to further refine the non-local DFT functionals. Moreover, by virtue of these properties, h-BP can be the best choice to be used as an anode material not only in LIBS but also in SIBs and KIBs.Graphical abstracthBP is found to be an excellent anode materials for alkali-based batteries in terms of excellent storage capacities and good OCVs. The key electrochemical properties are found to be quite sensitive to the choice of DFT functionals.Graphical abstract for this article
       
  • Active {1 1 1}-faceted ultra-thin NiO single-crystalline porous
           nanosheets supported highly dispersed Pt nanoparticles for synergetic
           enhancement of gas sensing and photocatalytic performance
    • Abstract: Publication date: 31 March 2019Source: Applied Surface Science, Volume 471Author(s): Yan Liang, Yong Yang, Hang Zhou, Chengwu Zou, Keng Xu, Xingfang Luo, Ting Yu, Yanting Liu, Mengqi Ding, Cailei Yuan Proper morphology, surface and interface structure designing are required to obtain efficient gas sensing and photocatalytic materials. In the present work, ultra-thin NiO single-crystalline porous nanosheets with dominant {1 1 1} crystal facets (denoted as SP-NiO) and hierarchical NiO porous microspheres (denoted as HP-NiO) supported highly dispersed Pt nanoparticles with controllable sizes were designed and synthesized. Their gas sensing and photocatalytic performance were investigated. It was found that both the formaldehyde sensing and methyl orange photocatalytic degradation performance were greatly enhanced by decorating Pt nanoparticles on SP-NiO, while Pt nanoparticles decoration contributed little to the improved photocatalytic performance of HP-NiO. The results indicated that surface structure of the NiO support could also produce significant impact on the activity of Pt/NiO heterojunctions. Moreover, Pt decorated SP-NiO with stable structure showed a marked long-term stability with negligible attenuation of gas sensitivity (less than 5%) for 45 days, while Pt decorated HP-NiO exhibited obvious attenuation of gas sensitivity (more than 30%) due to the structural collapse. The work not only offers promising materials for gas sensing and photocatalytic application, but also brings new dawn for the designing of efficient p-type metal oxides gas sensing and photocatalytic materials through the synergistic effect of single-crystalline porous structures modulation, crystal facets engineering and facet-selective deposition of highly-dispersed Pt nanoparticles.Graphical abstractActive {1 1 1}-faceted ultra-thin NiO single-crystalline porous nanosheets supported highly dispersed Pt nanoparticles were designed and synthesized for efficient gas sensing and photocatalytic applications.Graphical abstract for this article
       
  • Two-dimensional Dy doped MoS2 ferromagnetic sheets
    • Abstract: Publication date: 31 March 2019Source: Applied Surface Science, Volume 471Author(s): Qi Zhao, Qing Lu, Yi Liu, Mingzhe Zhang Magnetic two-dimensional materials have attracted immense consideration as spintronic devices. However, design and synthesis of the magnetic two-dimensional MoS2 crystals with more controllable electronic structure and better conductivity are still great challenges. Here, we make a breakthrough to synthesize the MoS2:Dy sheets with robust adjustable room-temperature ferromagnetic properties by a gas-liquid chemical deposition method. The as-synthesized samples are characterized by XRD, Raman, TEM, HRTEM and XPS. Furthermore, the magnetic properties of the samples are also investigated by VSM and Squid. The maximum observed saturation magnetization is 0.023 emu/g. The origin of ferromagnetism in the samples is investigated by using the first-principles calculations based on the density functional theory. The ferromagnetism is mainly related to the exchange interactions among the S 3p, Mo 4d and Dy 5d orbits. The results indicate that the transformation of the localized charges can effectively engineer and manipulate the magnetic properties of 2D materials, making MoS2 a potential candidate for spintronics and electronic applications and providing a new perspective on other 2D layered materials in spintronics application.Graphical abstractGraphical abstract for this article
       
  • Effect of Nb content on corrosion behavior of Ti-based bulk metallic glass
           composites in different solutions
    • Abstract: Publication date: 31 March 2019Source: Applied Surface Science, Volume 471Author(s): Y.J. Yang, X.D. Fan, F.L. Wang, H.N. Qi, Y. Yue, M.Z. Ma, X.Y. Zhang, G. Li, R.P. Liu The effect of Nb content on the corrosion behavior of in-situ (Ti0.45Zr0.31Be0.17Cu0.07)100−xNbx (x = 4, 6, 8, 10, and 12) was evaluated in 0.5 mol/L H2SO4, 0.6 mol/L NaCl, and 1 mol/L NaOH solutions. A dual-phase microstructure which composed of an amorphous matrix and dendrites was observed. Electrochemical measurements in each corrosion medium showed the same trend. The corrosion resistance first increased and then decreased with the addition of Nb content from 4 to 12 at.%. The results show the best corrosion resistance in terms of ×  = 8 for the alloys. Notably, Nb addition improved the pitting-corrosion resistance of samples in a chloride-containing solution, whereas spontaneous passivation occurred in chloride-free solutions. A preferential solution was observed in the amorphous matrix region in NaCl solution, but a part of dark spots and dents appeared on the surface after the polarization in chloride-free solutions. X-ray photoelectron spectroscopic measurements showed that Nb addition promoted the formation of metal oxide on the surface film, thus inducing a superior corrosion resistance for the bulk metallic glass matrix composites.
       
  • Synthesis of polyethylenimine/graphene oxide for the adsorption of U(VI)
           from aqueous solution
    • Abstract: Publication date: 31 March 2019Source: Applied Surface Science, Volume 471Author(s): Hongjuan Liu, Yuancheng Zhou, Yibo Yang, Ke Zou, Renjie Wu, Ke Xia, Shuibo Xie Polyethyleneimine (PEI)/graphene oxide (GO) was synthesized through a self-assembly method with the formation of the amide group CONH between NH2 on PEI and COOH on GO. The formation was confirmed by Fourier transform infrared spectroscopy (FT-IR) and X-ray photoelectron spectroscopy (XPS). The oxygen- and nitrogen-containing functional groups of PEI/GO were involved in the adsorption of U(VI), as determined under the FT-IR and XPS analyses of PEI/GO and U(VI)-adsorbed PEI/GO. The pH, contact times, and initial concentration, which are the factors influencing the removal of U(VI), were investigated. The adsorption of U(VI) onto PEI/GO was fitted well with the pseudo-second-order kinetic model and Langmuir isotherm model. The maximum sorption capacities of U(VI) on PEI/GO (145.14 mg·g−1) at pH = 7 and T = 303 K were higher than that of U(VI) on GO (94.61 mg·g−1). This study provides a novel and simple method for synthesizing GO derivatives with efficient adsorption performances of U(VI) from aqueous solution.Graphical abstractGraphical abstract for this article
       
  • ToF-SIMS investigation of absorption of lead and bismuth in T91 steel
           deformed in liquid lead bismuth eutectic
    • Abstract: Publication date: 31 March 2019Source: Applied Surface Science, Volume 471Author(s): Ingrid Proriol Serre, Jean-Bernard Vogt, Nicolas Nuns The time of flight secondary ion mass spectroscopy (ToF-SIMS) technique was employed to investigate the interaction of liquid lead-bismuth eutectic (LBE) atoms with the surface and subsurface of a T91 steel taking into account the contribution of plastic deformation. It is shown that both Pb and Bi can penetrate the steel network only in plastically deformed material. No microstructural interface (lath boundaries, grain boundaries …) was found to be preferential site for trapping Pb and Bi but clustering with molybdenum has been identified. Pb seems to be easier adsorbed than Bi because of its higher affinity with oxygen.Graphical abstractGraphical abstract for this article
       
  • First-principle study on honeycomb fluorated-InTe monolayer with large
           Rashba spin splitting and direct bandgap
    • Abstract: Publication date: 31 March 2019Source: Applied Surface Science, Volume 471Author(s): Kaixuan Li, Xiujuan Xian, Jiafu Wang, Niannian Yu Rashba effect is much related to next-generation spintronic devices. It is highly desirable to search for Rashba materials with large Rashba spin splitting, which is considered as the key factor for the application of spin field-effect transistor. Here, we design a two-dimensional monolayer of fluorated-InTe (InTeF) with large Rashba spin splitting and direct bandgap on the basis of first-principles calculations. InTeF monolayer is energetically and dynamically stable based on the calculations of cohesive energy and phonon dispersion. Remarkably, the Rashba parameter αR is about 1.08 eV·Å, comparable to that of the BiTeI monolayer (1.86 eV·Å). The direct bandgap is estimated to be 2.48 eV by HSE06 hybrid functional, which shows good prospects in light-emitting devices and photodetectors. To further explore the effect of substrates on the electronic structure of InTeF monolayer, we build two heterostructures, and the results show that the strength of Rashba effect and the direct bandgap nature in InTeF monolayer can be well preserved under the influence of substrates. Based on the above findings in our work, InTeF monolayer is considered to be one of the promising 2D materials for the application of spintronics as well as optoelectronics.
       
  • Engineering hierarchical porous oxygen-deficient TiO2 fibers decorated
           with BiOCl nanosheets for efficient photocatalysis
    • Abstract: Publication date: 31 March 2019Source: Applied Surface Science, Volume 471Author(s): Shuai Zhou, Nan Bao, Qingzhe Zhang, Xiuyan Jie, Yuchao Jin The hierarchical porous oxygen-deficient TiO2 (TiO2-δ) fibers decorated with BiOCl nanosheets, for the first time, were synthesized through a sol-gel method combined with centrifugal spinning, and subsequent heat treatment under steam. Therein, the byproduct water-soluble NaCl crystal was recycled and used as the self-manufactured and self-sacrificial template. The dissolving out of NaCl for the in situ preparation of BiOCl on the surface of TiO2-δ generates rich mesoporous fiber structure. The flower-like BiOCl nanosheets provide large surface area for the adsorption of reactants, and more light scattering/reflection channels for enhancing light absorption. A series of characterizations confirmed that the introduction of oxygen vacancies in TiO2 broadens the light response to visible range, and the promotion of charge separation due to the formation of p-n junction between BiOCl and TiO2-δ. As a result, the BiOCl/TiO2-δ fiber exhibits enhanced broadband photocatalytic performance in the degradation of reactive brilliant red and colorless phenol. The apparent reaction rate constant achieved by the optimized BiOCl/TiO2-δ composite (0.0636 min−1) far surpasses that of TiO2-δ fibers (0.0026 min−1) by a factor of 24 under visible light irradiation. The reactive species involved in photocatalysis were detected by scavenger experiments and electron spin resonance spectra. The possible charge transfer processes and mechanism were explored and discussed in detail. This work provides novel insight into the design and synthesis of broadband and effective heterostructure photocatalysts for practical wastewater treatment.Graphical abstractGraphical abstract for this article
       
  • Evaluation of the colloidal stability and adsorption performance of
           reduced graphene oxide–elemental silver/magnetite nanohybrids for
           selected toxic heavy metals in aqueous solutions
    • Abstract: Publication date: 31 March 2019Source: Applied Surface Science, Volume 471Author(s): Chang Min Park, Dengjun Wang, Jonghun Han, Jiyong Heo, Chunming Su Reduced graphene oxide (rGO) hybridized with magnetite and/or elemental silver (rGO/magnetite, rGO/silver, and rGO/magnetite/silver) nanoparticles were evaluated as potential adsorbents for toxic heavy metal ions (Cd(II), Ni(II), Zn(II), Co(II), Pb(II), and Cu(II)). Although the deposition of iron oxide and silver nanoparticles on the rGO nanosheets played an inhibitory role in metal ion adsorption, the metal adsorption efficiency by the nanohybrids (NHs) was still higher than that reported for many other sorbents (e.g., activated biochar, commercial resins, and nanosized hydrated Zr(IV) oxide particles). X-ray photoelectron spectroscopy analyses revealed that complexation with deprotonated adsorbents and cation exchange was an important mechanism for Cd(II) ion removal by the rGO and NHs. Competitive adsorption tests using multi metals showed that the adsorption affinity of metal ions on the rGO and its NHs follows the order (Cu(II), Zn(II)) > Ni(II) > Co(II) > (Pb(II), Cd(II)), which is similar to the order observed for single-metal adsorption experiments. These results can be explained by the destabilization abilities of the rGO and NHs, as well as the ionic radii of the considered metal ions. Our findings demonstrate the feasibility of using rGO-based NHs as highly efficient adsorbents for heavy metal removal from water.
       
  • Composited micropores constructed by amorphous TiO2 and graphene for
           degrading volatile organic compounds
    • Abstract: Publication date: 31 March 2019Source: Applied Surface Science, Volume 471Author(s): Le Yue, Rui Cheng, Weiqi Ding, Junwei Shao, Ji Li, Jinze Lyu The adsorption ability and photoactivity of photocatalysts directly determine the mineralization efficiency of volatile organic compounds. In this study, a 2D–2D microporous structure of amorphous TiO2 nanoparticles and graphene (GR) was constructed to simultaneously enhance the adsorption ability and charge separation efficiency of catalysts. N2 adsorption–desorption, scanning electron microscopy, high-resolution transmission electron microscopy, X-ray photoelectron spectroscopy, and X-ray diffraction measurements were conducted to investigate the physical properties of the prepared samples. The atmospheric surface photovoltage (SPV) was utilized to study the separation process of the photogenerated charge carriers. Toluene was chosen as the model agent to estimate the adsorption ability and photoactivity of the samples. Results showed that the amorphous TiO2 nanoparticles homogeneously deposited onto the GR surface and hence formed a 2D–2D microporous structure. Although the surface area of the GR–TiO2 compositions increased by only 4–8% relative to that of microporous TiO2 alone, the amount of adsorbed toluene for the GR–TiO2 compositions was 156–193% times higher than that for the microporous TiO2. The SPV result proved that the GR significantly enhanced the intrinsic separation of the photogenerated charge carriers. The contribution of O2 and the GR to the charge separation was dependent on the weight addition ratio of the GR. The GR dominated the charge separation process as its weight addition ratio ≥5%. Given the advantages in adsorption ability and photoactivity, toluene showed mineralization efficiencies for the composite with 5.0 wt% GR of 1.4 and 2.7 folds those of microporous TiO2 and P25, respectively, after 96 min irradiation.Graphical abstractGraphical abstract for this article
       
  • Micro-chemical investigation of corrosion products naturally grown on
           archaeological Cu-based artefacts retrieved from the Mediterranean sea
    • Abstract: Publication date: 15 March 2019Source: Applied Surface Science, Volume 470Author(s): G.M. Ingo, C. Riccucci, G. Guida, M. Pascucci, C. Giuliani, E. Messina, G. Fierro, Gabriella Di Carlo The corrosion products naturally formed on archaeological Cu-based artefacts during their long-term exposure to seawater have been investigated in details by means of X-ray diffraction (XRD), scanning electron microscopy coupled with energy dispersive spectrometry (SEM + EDS), optical microscopy (OM), attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR), differential thermal analysis-thermogravimetry (DTA-TG), inductively coupled plasma mass spectrometry (ICP-MS) and X-ray photoelectron spectroscopy (XPS). The bronze artefacts include fragments of valuable statues and objects that were retrieved some decades ago from different seabeds along the Italian coast of the Mediterranean basin including the so called “Punta del Serrone” area (Apulia), the Sicilian channel (Sicily) and the Arburese coast (Sardinia). Our findings show that the alloy matrix is often heavily corroded also in the bulk and reveal the dangerous presence of chlorine from seawater as main dangerous corrosive agent. Chlorine is present as copper nantokite (CuCl) in the inner layers of the patina and is potentially inducing with oxygen and moisture the cyclic and often relentless copper degradation phenomenon commonly called “bronze disease”. The most common corrosion products are also lead carbonate (cerussite, PbCO3) and aragonite (CaCO3), likely related to the large abundance of CO2 in the seawater where is assimilated much more than in fresh water. Furthermore, the results reveal that other environmental elements contributing to the composition of the patina are sulphur, magnesium and phosphorous thus giving rise to a patina with a chemically and structurally complex structure. The results reveal also the contribution of bio-organism to the formation of the patina as supported by the presence of vanadium and copper sulphides. These information allow, as a whole, to propose a tentative correlation between the patina’s nature, the chemical composition and metallurgical features of the alloys and the marine environment where the objects lived for about two thousands years. From a conservation point of view, the findings reported in this work can provide some insights useful to tailor more efficient conservation strategies with the purpose to ensure a long-term chemical-physical stability to the bronze artefacts.
       
  • Chirality of laser-printed plasmonic nanoneedles tunable by tailoring
           spiral-shape pulses
    • Abstract: Publication date: 15 March 2019Source: Applied Surface Science, Volume 470Author(s): Sergey Syubaev, Aleksey Zhizhchenko, Oleg Vitrik, Aleksey Porfirev, Sergey Fomchenkov, Svetlana Khonina, Sergey Kudryashov, Aleksandr Kuchmizhak We report on fabrication of Ag nanoneedles with tailored chirality via direct ns-laser printing with “structured” laser beams, zero-optical-angular momentum spiral-shaped beams with variable intensity profiles as well as the perfect optical vortex (POV) beams having fixed donut-shaped intensity pattern and variable topological charge. The chirality of the laser-printed nanoneedles was found to be efficiently tailored via optimization of the corresponding intensity pattern of the zero-OAM spiral-shaped beam, while the increase of the topological charge of the POV beam was shown to weakly affect the nanoneedle geometry. Our comparative study reveals the key role of the initial surface intensity (temperature) distribution driving the helical movement of the transiently molten metal and directing formation of the nanoneedles with pronounced chirality on the surface of the noble-metal films. The obtained results pave the way toward realization of easy-to-implement scalable technology for the direct laser printing of plasmonic nanoneedles with pronounced and tailored chirality suited for various nanophotonic, chemical and biosensing applications.Graphical abstractGraphical abstract for this article
       
  • Laser surface texturing of copper and variation of the wetting response
           with the laser pulse fluence
    • Abstract: Publication date: Available online 27 November 2018Source: Applied Surface ScienceAuthor(s): Elaheh Allahyari, Jijil JJ Nivas, Stefano L. Oscurato, Marcella Salvatore, Giovanni Ausanio, Antonio Vecchione, Rosalba Fittipaldi, Pasqualino Maddalena, Riccardo Bruzzese, Salvatore Amoruso We report an experimental investigation on laser surface texturing of copper targets by Ti:Sa femtosecond laser pulses addressing their wetting response to water droplets. In particular, fs laser surface processing is used to developed hierarchical surface structures by writing parallel micro-trenches with a period of 50 μm at different laser pulse fluences. The laser irradiation simultaneously induces both the formation of laser induced periodic surface structures (LIPSS), in form of periodic ripples, and the random decoration with nanoparticles, resulting in the formation of a multiscale surface morphology. The morphological features of the samples are investigated and correlated with their wetting response through static contact angle measurements. Our findings evidence a progressive increase of the contact angle with the laser pulse fluence. The combination of the microscale trenches, written by laser line scanning, with the ripples patterns and the random nanoparticles decoration, formed on the surface, allow developing highly hydrophobic copper samples with contact angles reaching values around 160°, presenting potential interest for wettability applications.
       
  • High-throughput laser generation of Si-nanoparticle based surface coatings
           for antibacterial applications
    • Abstract: Publication date: Available online 27 November 2018Source: Applied Surface ScienceAuthor(s): Sergey I. Kudryashov, Alena A. Nastulyavichus, Anastasiya K. Ivanova, Nikita A. Smirnov, Roman A. Khmelnitskiy, Andrey A. Rudenko, Irina N. Saraeva, Etery R. Tolordava, Alexander Yu. Kharin, Irina N. Zavestovskaya, Yulia M. Romanova, Dmitry A. Zayarny, Andrey A. Ionin High-productivity regime of nanosecond IR-laser ablative generation of silicon colloidal solutions in water for anti-bacterial applications was found in terms of GW/cm2-level laser intensity and scanning velocity by measuring multi-shot ablative mass loss and extinction coefficients of the colloids as sub-linear and third-power intensity functions, respectively. This advantageous regime implies sub-linear mass loss versus laser intensity at the simultaneous third-power yield of nanoparticles, resulting from the subcritical-density, opaque ablative plasma regulating the sample ablation rate and plathe related sma-mediated dissociation (dispergation) of the ablation products. In contrast, at higher intensities, there is a drastic increase in mass loss with the corresponding increased yield of (sub) micrometer-sized particles owing to intense plasma-driven expulsion of micro-scale melt droplets and the corresponding saturation of the extinction coefficient of the colloidal solutions because of their dynamic local “self-limiting” effect during the high-rate ablation. The optimal low-intensity regime for Si nanoparticle production demonstrates the monotonous correlated increase of mass loss and extinction coefficient in terms of increasing laser scanning velocity, indicating the diminished cumulative effects. Surface coatings prepared from the generated Si nanoparticles exhibit minor surface oxidation, as acquired as their elemental composition via energy-dispersive X-ray spectroscopy, making their contact angle for water droplets (≈51o) close to that of bare Si wafer (≈58o) with its nanometer-thick native oxide layer. Owing to good wetting, the nanoparticle-based surface coatings show strong antibacterial response regarding Gram-negative Pseudomonas Auereginosa bacteria even despite their minor oxidative passivation.Graphical abstractGraphical abstract for this article
       
  • Surface studies of patinas and metallurgical features of uncommon high-tin
           bronze artefacts from the Italic necropolises of ancient Abruzzo (Central
           Italy)
    • Abstract: Publication date: Available online 16 November 2018Source: Applied Surface ScienceAuthor(s): G.M. Ingo, C. Riccucci, C. Giuliani, A. Faustoferri, I. Pierigè, G. Fierro, M. Pascucci, M. Albini, G. Di Carlo Archaeological high-tin copper-based artefacts, dated back to VIII and IV centuries BC and recently discovered in the Italic necropolises of ancient Abruzzo (Central Italy), were investigated in order to determine the micro-chemical and micro-structural nature of the corrosion products and the chemical composition and metallurgical features of the alloys. The Cu-based artefacts were defensive weapons mainly as bronze belts and pectoral disc armours with engraved decorations. A rather detailed picture of the chemical composition, structural and morphological characteristics of such Cu-based artefacts was provided by combining different techniques as scanning electron microscopy coupled with energy dispersive spectroscopy (SEM-EDS), attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR), X-ray photoelectron spectroscopy (XPS), optical microscopy (OM) and X-ray diffraction (XRD) analysis. The results, as a whole, evidence that some artefacts were manufactured by casting and shaping uncommon high-tin bronze alloys thus conferring an attractive silver-like appearance. The manufacturing process was based on tailored multiple hot hammering, carefully carried out at about 700 °C to shape the high-tin alloys in the form of sheets avoiding breaking. The mechanical work was followed by an annealing treatment, polishing and final decorative finishing. Furthermore, our investigation on the corrosion process, suggest that it is a mixture of rather complex phenomena leading to the degradation of the main alloying elements which give rise to mineral alteration products in the form of complex structures. These latter contain SnO2 (cassiterite), cuprous oxide, copper carbonates (azurite and malachite) and, in particular, chlorine-based compounds like nantokite and atacamite and its polymorphs, which have heavy detrimental effects, their presence being considered a symptom of the destructive “bronze disease” degradation phenomenon. Moreover, it was found an unusual presence of re-deposited Cu inclusions to be likely related to long-term corrosion processes and to a low oxygen availability in the burial environment. All these findings show, as a whole, that there is a strict relationship between alloy elements, metallurgical features, burial soil conditions and chemical and structural features of the corrosion products. This paper highlights also as the combined use of different techniques as SEM-EDS, ATR-FTIR, XPS, XRD and OM can be one of the possible successfully way to study the corrosion products of archaeological copper-based artefacts, thus helping to choose the more appropriate strategies for the long-lasting conservation of archaeological bronze artworks, in most cases so valuable for the cultural heritage.
       
 
 
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