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Advanced Functional Materials
[SJR: 5.21] [H-I: 203] [50 followers] Follow

Hybrid journal (It can contain Open Access articles)
ISSN (Print) 1616-301X - ISSN (Online) 1616-3028
Published by John Wiley and Sons

[1584 journals]

Self-Templated Fabrication of CoO–MoO2 Nanocages for Enhanced Oxygen
Evolution
- Authors: Fenglei Lyu; Yaocai Bai, Zhiwei Li, Wenjing Xu, Qingfa Wang, Jing Mao, Li Wang, Xiangwen Zhang, Yadong Yin
  Abstract: Oxygen evolution reaction (OER) plays a key role in energy conversion and storage processes such as water splitting and carbon dioxide reduction. However, the sluggish kinetics caused by insufficient active surface and limited charge transfer hinder OER's wide applications. In this work, a novel self-templating strategy for the fabrication of composite CoO–MoO2 nanocages with enhanced OER performance is proposed. By designing a nanocage structure and incorporating conductive MoO2 to promote both mass and charge transfer, high OER activity (η = 312 mV at 10 mA cm−2) as well as good stability in the resulting CoO–MoO2 composite nanostructure can be achieved. This versatile synthetic strategy can also be extended to other metals (such as W) to provide greater opportunities for the controlled fabrication of mixed metal oxide nanostructures for electrochemical applications.A novel self-templating strategy is developed for the fabrication of composite CoO–MoO2 nanocages with enhanced oxygen evolution reaction (OER) performance. The enhanced OER performance can be attributed to the enlarged electrochemically active surface area and favorable charge transfer due to the incorporation of Mo species. This strategy provides great opportunities for the design and synthesis of mixed metal oxides for electrochemical applications.
  PubDate: 2017-07-20T04:18:46.677047-05:
  DOI: 10.1002/adfm.201702324
A Materials Roadmap to Functional Neural Interface Design
- Authors: Steven M. Wellman; James R. Eles, Kip A. Ludwig, John P. Seymour, Nicholas J. Michelson, William E. McFadden, Alberto L. Vazquez, Takashi D. Y. Kozai
  Abstract: Advancements in neurotechnologies for electrophysiology, neurochemical sensing, neuromodulation, and optogenetics are revolutionizing scientific understanding of the brain while enabling treatments and preventative measures for a variety of neurological disorders. The grand challenge in neural interface engineering is to seamlessly integrate the interface between neurobiology and engineered technology to record from and modulate neurons over chronic timescales. However, the biological inflammatory response to implants, neural degeneration, and long-term material stability diminishes the quality of the interface overtime. Recent advances in functional materials are aimed at engineering solutions for chronic neural interfaces, yet, the development and deployment of neural interfaces designed from novel materials have introduced new challenges that have been largely unaddressed. Many engineering efforts that solely focus on optimizing individual probe design parameters, such as softness or flexibility, downplay critical multidimensional interactions between different physical properties of the device that contribute to overall performance and biocompatibility. Moreover, the use of these new materials present substantial new difficulties that must be addressed before regulatory approval for use in human patients is achievable. In this review, the interdependence of different electrode components is highlighted to demonstrate the current material-based challenges facing the field of neural interface engineering.Neural interface engineering aims to apply advanced functional materials to seamlessly integrate neural technology with the nervous system in order to restore brain function in patients and uncover at least some of the brain's mysteries. This review highlights the challenges and interdependence of material components for long-term functional performance, and compiles a “roadmap” to guide material-based neural interface engineering.
  PubDate: 2017-07-19T06:57:27.633198-05:
  DOI: 10.1002/adfm.201701269
A Bi-Sheath Fiber Sensor for Giant Tensile and Torsional Displacements
- Authors: Run Wang; Nan Jiang, Jian Su, Qu Yin, Yue Zhang, Zhongsheng Liu, Haibao Lin, Francisco A. Moura, Ningyi Yuan, Siegmar Roth, Richard S. Rome, Raquel Ovalle-Robles, Kanzan Inoue, Shougen Yin, Shaoli Fang, Weichao Wang, Jianning Ding, Linqi Shi, Ray H. Baughman, Zunfeng Liu
  Abstract: Current research about resistive sensors is rarely focusing on improving the strain range and linearity of resistance–strain dependence. In this paper, a bi-sheath buckled structure is designed containing buckled carbon nanotube sheets and buckled rubber on rubber fiber. Strain decrease results in increasing buckle contact by the rubber interlayer and a large decrease in resistance. The resulting strain sensor can be reversibly stretched to 600%, undergoing a linear resistance increase as large as 102% for 0–200% strain and 160% for 200–600% strain. This strain sensor shows high linearity, fast response time, high resolution, excellent stability, and almost no hysteresis.Novel bi-sheath strain sensors for tensile and torsional strain are fabricated by hierarchically buckling an aligned carbon nanotube sheath on a buckled elastomer-coated rubber fiber. The contact area between adjacent nanotube buckles decreases with increasing stretch to provide 160% increase in resistance during 600% sensor elongation, which is fast in response, low in hysteresis, and high in cycle life.
  PubDate: 2017-07-19T01:48:58.413021-05:
  DOI: 10.1002/adfm.201702134
Carbon Nanotube Wires Sheathed by Aramid Nanofibers
- Authors: Wenxin Cao; Lei Yang, Xiaodong Qi, Ying Hou, Jiaqi Zhu, Ming Yang
  Abstract: Coaxial fibers are the key elements in many optical, electrical, and biomedical applications. Recent success in materials synthesis has provided versatile choices for the core part, but the search of high-performance sheath materials remains much less productive. These surface coatings are however as important as the core for their role as protection layers and interaction medium with the externals, thereby critically affecting the real performance of coaxial fibers. Here it is shown that aramid nanofibers (ANFs) with exceptional environmental stability and mechanical properties can be advanced coating materials for both wet- and dry-spun carbon nanotube (CNT) wires. Co-wet-spinning ANFs with CNT aqueous dispersion can produce coaxial fibers with a compact sheath comprised of aligned ANFs, showing much enhanced mechanical properties by transferring stress to the sheath without sacrificing the conductivity. On the other hand, an immersion-precipitation process is used to prepare a porous sheath made from randomly distributed nanofibers on dry-spun CNT wires, which can be combined with ionic conductive gel electrolyte as a strong packaging layer for flexible solid-state supercapacitors. The excellent intrinsic characteristics as well as variable ways of structural organizations make ANF-based coatings an attractive tool for the design of multifunctional high-performance hybrid materials.Aramid nanofibers (ANFs) are demonstrated as multifunctional coating materials for carbon nanotube (CNT) wires in a coaxial geometry. A dense ANF sheath with a good alignment renders wet-spun CNT wires with much improved mechanical properties without sacrificing electrical conductivity and a porous ANF sheath consisted of randomly distributed ANFs is combined with gel electrolytes as reinforced packaging layer for solid-state supercapacitors.
  PubDate: 2017-07-19T01:48:00.108188-05:
  DOI: 10.1002/adfm.201701061
Tissue Engineered Bio-Blood-Vessels Constructed Using a Tissue-Specific
Bioink and 3D Coaxial Cell Printing Technique: A Novel Therapy for
Ischemic Disease
- Authors: Ge Gao; Jun Hee Lee, Jinah Jang, Dong Han Lee, Jeong-Sik Kong, Byoung Soo Kim, Yeong-Jin Choi, Woong Bi Jang, Young Joon Hong, Sang-Mo Kwon, Dong-Woo Cho
  Abstract: Endothelial progenitor cells (EPCs) are a promising cell source for the treatment of several ischemic diseases for their potentials in neovascularization. However, the application of EPCs in cell-based therapy has shown low therapeutic efficacy due to hostile tissue conditions after ischemia. In this study, a bio-blood-vessel (BBV) is developed, which is produced using a novel hybrid bioink (a mixture of vascular-tissue-derived decellularized extracellular matrix (VdECM) and alginate) and a versatile 3D coaxial cell printing method for delivering EPC and proangiogenic drugs (atorvastatin) to the ischemic injury sites. The hybrid bioink not only provides a favorable environment to promote the proliferation, differentiation, and neovascularization of EPCs but also enables a direct fabrication of tubular BBV. By controlling the printing parameters, the printing method allows to construct BBVs in desired dimensions, carrying both EPCs and atorvastatin-loaded poly(lactic-co-glycolic) acid microspheres. The therapeutic efficacy of cell/drug-laden BBVs is evaluated in an ischemia model at nude mouse hind limb, which exhibits enhanced survival and differentiation of EPCs, increased rate of neovascularization, and remarkable salvage of ischemic limbs. These outcomes suggest that the 3D-printed ECM-mediated cell/drug implantation can be a new therapeutic approach for the treatment of various ischemic diseases.The extracellular matrix of vascular tissue is formulated as a bioink to engineer a bioinspired blood vessels using the 3D coaxial cell printing technique. Carrying progenitor cells and proangiogenic drugs, the transplanted construct exhibits remarkable therapeutic efficacy for ischemic diseases.
  PubDate: 2017-07-19T01:46:59.373744-05:
  DOI: 10.1002/adfm.201700798
Side Group Engineering of Small Molecular Acceptors for High-Performance
Fullerene-Free Polymer Solar Cells: Thiophene Being Superior to
Selenophene
- Authors: Wei Gao; Qiaoshi An, Ruijie Ming, Dongjun Xie, Kailong Wu, Zhenghui Luo, Yang Zou, Fujun Zhang, Chuluo Yang
  Abstract: Side group of ITIC-like small molecular acceptor (SMA) plays a critical role in crystallization property. In this article, two new SMAs with n-hexylthienyl and n-hexylselenophenyl as side chain, namely ITCPTC-Th and ITCPTC-Se, are designed and synthesized by employing newly developed thiophene-fused ending group (CPTCN). And thiophene and selenophene side group substituted effects of SMA-based fullerene-free polymer solar cells (PSCs) are investigated. A stronger σ-inductive effect between selenophene side group and electron-donating backbone endows ITCPTC-Se with better optical absorption and higher LUMO level, ITCPTC-Th-based PSCs deliver a higher power conversion efficiency of 10.61%. Charge transport and collection, recombination loss mechanism, and morphology of blend films are intensively studied. These results confirm that side group substituted effects of SMAs are multiple and thiophene is a superior option to selenophene as aromatic side group of ITIC-like SMAs.Two new small molecular acceptors (SMAs), ITCPTC-Th and ITCPTC-Se, are designed and synthesized to investigate thiophene and selenophene side group substituted effects. A polymer solar cell (PSC) based on ITCPTC-Th achieves high power conversion efficiency (PCE) of 10.61%, which are significantly higher than that of ITCPTC-Se-based PSC. This confirms that thiophene is superior to selenophene as side group of ITIC-like SMAs.
  PubDate: 2017-07-19T01:40:56.526155-05:
  DOI: 10.1002/adfm.201702194
Organic Electrodes and Communications with Excitable Cells
- Authors: Alexander R. Harris; Gordon G. Wallace
  Abstract: Electrodes can provide information on neural function and stimulate neural activity. These neural electrodes can provide remarkable benefit to people suffering physical trauma or neural disease. Traditional metal electrodes have shortcomings related to poor biostability, cytocompatibility, and a rigid structure that maps poorly to tissue. Organic conductors can be formed with various chemical and physical properties to create improved electrode-neural interfaces. The processability of organic conductors enables their use in advanced fabrication methods. This review details the use of graphene, carbon nanotubes, and conducting polymers for neural interfacing. Construction of novel neural electrode architectures via advanced fabrication processes is also addressed.Organic materials can control cell behavior; organic conducting materials are also able record and stimulate excitable cells. This review covers graphene, carbon nanotubes, and organic conducting polymers interfacing with cells. Different methods of fabricating electrode structures are also discussed.
  PubDate: 2017-07-18T04:48:43.699234-05:
  DOI: 10.1002/adfm.201700587
Electrospun Extracellular Matrix: Paving the Way to Tailor-Made Natural
Scaffolds for Cardiac Tissue Regeneration
- Authors: Beth Schoen; Ron Avrahami, Limor Baruch, Yael Efraim, Idit Goldfracht, Ofek Elul, Tzila Davidov, Lior Gepstein, Eyal Zussman, Marcelle Machluf
  Abstract: Biomimetic scaffolds generally aim at structurally and compositionally imitating native tissue, thus providing a supportive microenvironment to the transplanted or recruited cells in the tissue. Native decellularized porcine extracellular matrix (ECM) is becoming the ultimate bioactive material for the regeneration of different organs. Particularly for cardiac regeneration, ECM is studied as a patch and injectable scaffolds, which improve cardiac function, yet lack reproducibility and are difficult to control or fine-tune for the desired properties, like most natural materials. Seeking to harness the natural advantages of ECM in a reproducible, scalable, and controllable scaffold, for the first time, a matrix that is produced from whole decellularized porcine cardiac ECM using electrospinning technology, is developed. This unique electrospun cardiac ECM mat preserves the composition of ECM, self-assembles into the same microstructure of cardiac ECM ,and ,above all, preserves key cardiac mechanical properties. It supports cell growth and function, and demonstrates biocompatibility in vitro and in vivo. Importantly, this work reveals the great potential of electrospun ECM-based platforms for a wide span of biomedical applications, thus offering the possibility to produce complex natural materials as tailor-made, well-defined structures.Electrospinning of extracellular matrix (ECM) enables, for the first time, the tailor-made production of natural bioactive scaffolds. The development of an electrospun scaffold that is produced solely from whole decellularized porcine cardiac ECM is demonstrated. This scaffold preserves the most critical properties and functions of native cardiac ECM, while allowing a controlled, reproducible production.
  PubDate: 2017-07-18T04:47:26.119267-05:
  DOI: 10.1002/adfm.201700427
Batteries: Oxygen Vacancies Evoked Blue TiO2(B) Nanobelts with Efficiency
Enhancement in Sodium Storage Behaviors (Adv. Funct. Mater. 27/2017)
- Authors: Yan Zhang; Zhiying Ding, Christopher W. Foster, Craig E. Banks, Xiaoqing Qiu, Xiaobo Ji
  Abstract: In article number 1700856, Xiaobo Ji and co-workers propose oxygen-vacancies-(OVs)-evoked blue TiO2(B) nanobelts as a superior anode for sodium-ion batteries. The anode feaures remarkable sodium storage behavior and marvelous long-term cyclability, owing to promoted electrochemical kinetics stimulated by OVs and shortened Na+ diffusion length due to the unique nanotubes/nanobelts morphology.
  PubDate: 2017-07-17T08:47:46.128203-05:
  DOI: 10.1002/adfm.201770161
Liquid Crystals: Tunable Gas Sensing Gels by Cooperative Assembly (Adv.
Funct. Mater. 27/2017)
- Authors: Abid Hussain; Ana T. S. Semeano, Susana I. C. J. Palma, Ana S. Pina, José Almeida, Bárbara F. Medrado, Ana C. C. S. Pádua, Ana L. Carvalho, Madalena Dionísio, Rosamaria W. C. Li, Hugo Gamboa, Rein V. Ulijn, Jonas Gruber, Ana C. A. Roque
  Abstract: Jonas Gruber, Ana C. A. Roque, and co-workers report a tunable gas-sensing gel in article number 1700803. The gel is generated by cooperative self-assembly of liquid crystals, biopolymers, and ionic liquid. Thin films react to stimuli by generating optical and electrical signals. Compared to metal oxide semiconductor based gas sensors, the system is more stable, operates at low temperatures and can be prepared without toxic material.
  PubDate: 2017-07-17T08:47:42.141616-05:
  DOI: 10.1002/adfm.201770166
Supercapacitors: Conductive Metal–Organic Framework Nanowire Array
Electrodes for High-Performance Solid-State Supercapacitors (Adv. Funct.
Mater. 27/2017)
- Authors: Wen-Hua Li; Kui Ding, Han-Rui Tian, Ming-Shui Yao, Bhaskar Nath, Wei-Hua Deng, Yaobing Wang, Gang Xu
  Abstract: In article number 1702067, Yaobing Wang, Gang Xu, and co-workers uniformly grow numerous nanowires of conductive metal-organic framework (MOF) on carbon fibre paper, which can be directly used as the electrode in supercapacitors. A symmetric solid-state supercapacitor composed of two identical electrodes and one separator is shown in the image. The material achieves the highest aerial capacitance and best rate performance reported yet for MOFs.
  PubDate: 2017-07-17T08:47:42.07861-05:0
  DOI: 10.1002/adfm.201770165
Nanogenerators: Supramolecular-Assembled Nanoporous Film with Switchable
Metal Salts for a Triboelectric Nanogenerator (Adv. Funct. Mater. 27/2017)
- Authors: Chanho Park; Giyoung Song, Suk Man Cho, Jihoon Chung, Yujeong Lee, Eui Hyuk Kim, Minjoo Kim, Sangmin Lee, June Huh, Cheolmin Park
  Abstract: A conventional, solution-based alkali metal ion exchange process generates a novel surface-tunable triboelectric nanogenerator in which the nanoporous surface can bind with alkali metal ions and permits easy exchange with other ions. The device, reported by June Huh, Cheolmin Park, and co-workers in article number 1701367, gives rise to the repetitive and reversible switching of triboelectric properties in a single-device platform.
  PubDate: 2017-07-17T08:47:41.72962-05:0
  DOI: 10.1002/adfm.201770162
Contents: (Adv. Funct. Mater. 27/2017)
- PubDate: 2017-07-17T08:47:40.218239-05:
  DOI: 10.1002/adfm.201770164
Masthead: (Adv. Funct. Mater. 27/2017)
- PubDate: 2017-07-17T08:47:40.150758-05:
  DOI: 10.1002/adfm.201770163
Discrete Iron(III) Oxide Nanoislands for Efficient and Photostable
Perovskite Solar Cells
- Authors: Qiang Luo; Haijun Chen, Yuze Lin, Huayun Du, Qinzhi Hou, Feng Hao, Ning Wang, Zhanhu Guo, Jinsong Huang
  Abstract: Perovskite solar cells typically use TiO2 as charge extracting materials, which reduce the photostability of perovskite solar cells under illumination (including ultraviolet light). Simultaneously realizing the high efficiency and photostability, it is demonstrated that the rationally designed iron(III) oxide nanoisland electrodes consisting of discrete nanoislands in situ growth on the compact underlayer can be used as compatible and excellent electron extraction materials for perovskite solar cells. The uniquely designed iron(III) oxide electron extraction layer satisfies the good light transmittance and sufficient electron extraction ability, resulting in a promising power conversion efficiency of 18.2%. Most importantly, perovskite solar cells fabricated with iron(III) oxide show a significantly improved UV light and long-term operation stabilities compared with the widely used TiO2-based electron extraction material, owing to the low photocatalytic activity of iron(III) oxide. This study highlights the potential of incorporating new charge extraction materials in achieving photostable and high efficiency perovskite photovoltaic devices.A photostable and efficient perovskite solar cell is presented, employing the rationally designed iron(III) oxide nanoarchitecture consisting of discrete nanoislands in situ growth on the compact underlayer as electron extraction layer. Perovskite solar cells fabricated with iron(III) oxide nanoislands exhibit high power conversion efficiency (over 18%) and promising ultraviolet light and long-term operational stabilities.
  PubDate: 2017-07-17T07:22:25.886836-05:
  DOI: 10.1002/adfm.201702090
A Mixed Component Supramolecular Hydrogel to Improve Mice Cardiac Function
and Alleviate Ventricular Remodeling after Acute Myocardial Infarction
- Authors: Guoqin Chen; Jinliang Li, Mingcai Song, Zhiye Wu, Wenzhu Zhang, Zhongyan Wang, Jie Gao, Zhimou Yang, Caiwen Ou
  Abstract: Myocardial infarction (MI) remains the major cause of death and disability in the world, and intramyocardial administration of biomaterials (e.g., hydrogels) along the perimeter of MI region is demonstrated as an effective way for the treatment of MI. The curcumin has anti-inflammation, antioxidation, and antiapoptosis properties, and nitric oxide (NO) molecules are favorable for angiogenesis. This study prepares a mixed component hydrogel capable of releasing both bioactive curcumin and NO for the treatment of MI. The study shows that the combinational treatment of curcumin and NO can remarkably reduce collagen deposition, improve cardiac function, ameliorate adverse myocardium remodeling, suppress apoptosis, and hypertrophy as well as attenuate the expression of matrix metalloproteinases (MMPs) and transforming growth factor-β1 (TGF-β1) and upregulate the expression of silent information regulator 1 than curcumin alone, because of the synergistic action of both molecules and the angiogenesis promotion ability of NO. The results indicate that codelivery of curcumin and NO in a controllable manner by hydrogels might be considered as a promising option for treatment of cardiovascular disease.A two component hydrogel capable of releasing both nitric oxide and curcumin to improve mice cardiac function and alleviate ventricular remodeling after acute myocardial infarction is presented.
  PubDate: 2017-07-17T07:22:06.763078-05:
  DOI: 10.1002/adfm.201701798
Structural Effects of Gating Poly(3-hexylthiophene) through an Ionic
Liquid
- Authors: Jesus O. Guardado; Alberto Salleo
  Abstract: Ionic liquids are increasingly employed as dielectrics to generate high charge densities and enable low-voltage operation with organic semiconductors. However, effects on structure and morphology of the active material are not fully known, particularly for permeable semiconductors such as conjugated polymers, in which ions from the ionic liquid can enter and electrochemically dope the semicrystalline film. To understand when ions enter, where they go, and how they affect the film, thin films of the archetypal semiconducting polymer, poly(3-hexylthiophene), are electrochemically doped with 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide, the archetypal ionic liquid. High-resolution, ex situ X-ray diffraction measurements and complete pole figures reveal changes with applied voltage, cycling, and frequency in lattice spacing, crystallite orientation, and crystallinity in the bulk and at the buried interface. Dopant ions penetrate the film and enter the crystallites at sufficiently high voltages and low frequencies. Upon infiltrating crystallites, ions permanently expand lamellar stacking and contract pi-stacking. Cycling amplifies these effects, but higher frequencies mitigate the expansion of bulk crystallites as ions are hindered from entering crystallites. This mechanistic understanding of the structural effects of ion penetration will help develop models of the frequency and voltage impedance response of electrochemically doped conjugated polymers and advance electronic applications.X-ray characterization reveals two regimes of structural change in thin films of polymer poly(3-hexylthiophene) gated through 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide. Tracking how ion penetration affects lattice spacing, crystalline orientation, and crystallinity elucidates mechanisms of the structural changes induced. Ions penetrate the film and enter crystallites at sufficiently high voltages and low frequencies. Cycling amplifies changes, though some effects are mitigated at higher frequencies.
  PubDate: 2017-07-17T07:21:42.863023-05:
  DOI: 10.1002/adfm.201701791
A 3D Hybrid of Chemically Coupled Nickel Sulfide and Hollow Carbon Spheres
for High Performance Lithium–Sulfur Batteries
- Authors: Chao Ye; Lei Zhang, Chunxian Guo, Dongdong Li, Anthony Vasileff, Haihui Wang, Shi-Zhang Qiao
  Abstract: Lithium–sulfur batteries are a promising next-generation energy storage device owing to their high theoretical capacity and the low cost and abundance of sulfur. However, the low conductivity and loss of active sulfur material during operation greatly limit the rating capabilities and cycling stability of lithium–sulfur batteries. In this work, a unique sulfur host hybrid material comprising nanosized nickel sulfide (NiS) uniformly distributed on 3D carbon hollow spheres (C-HS) is fabricated using an in situ thermal reduction and sulfidation method. In the hybrid material, the nanosized NiS provides a high adsorption capability for polysulfides and the C-HS serves as a physical confinement for polysulfides and also a 3D electron transfer pathway. Moreover, NiS has strong chemical coupling with the C-HS, favoring fast charge transfer and redox kinetics of the sulfur electrode. With a sulfur loading of up to 2.3 mg cm−2, the hybrid material-based lithium–sulfur batteries offer a capacity decay as low as 0.013% per cycle and a capacity of 695 mA h g−1 at 0.5 C after 300 cycles. This unique 3D hybrid material with strong chemical coupling provides a promising sulfur host for high performance lithium–sulfur batteries.A unique 3D hybrid of nickel sulfide (NiS) and carbon hollow spheres (C-HSs) is synthesized as a sulfur host. The uniformly distributed NiS greatly promote adsorption capability toward polysulfides.The C-HSs increase sulfur loading as well as the overall conductivity. This sulfur host achieves a capacity of 695 mA h g−1 after 300 cycles at 0.5 C.
  PubDate: 2017-07-17T07:16:56.642609-05:
  DOI: 10.1002/adfm.201702524
Surface Patterning of Hydrogels for Programmable and Complex Shape
Deformations by Ion Inkjet Printing
- Authors: Xin Peng; Tianqi Liu, Qin Zhang, Cong Shang, Qing-Wen Bai, Huiliang Wang
  Abstract: Convenient patterning and precisely programmable shape deformations are crucial for the practical applications of shape deformable hydrogels. Here, a facile and versatile computer-assisted ion inkjet printing technique is described that enables the direct printing of batched, very complicated patterns, especially those with well-defined, programmable variation in cross-linking densities, on one or both surfaces of a large-sized hydrogel sample. A mechanically strong hydrogel containing poly(sodium acrylate) is first prepared, and then digital patterns are printed onto the hydrogel surfaces by using a commercial inkjet printer and an aqueous ferric solution. The complexation between the polyelectrolyte and ferric ions increases the cross-linking density of the printed regions, and hence the gel sample can undergo shape deformation upon swelling/deswelling. The deformation rates and degrees of the hydrogels can be conveniently adjusted by changing the printing times or the different/gradient grayscale distribution of designed patterns. By printing appropriate patterns on one or both surfaces of the hydrogel sheets, many complex 3D shapes are obtained from shape deformations upon swelling/deswelling, such as cylindrical shell and forsythia flower (patterns on one surface), ding (patterns on both surfaces), blooming flower (different/gradient grayscale distributive patterns on one surface), and non-Euclidean plates (different/gradient grayscale distributive patterns on both surfaces).Computer-assisted ion inkjet printing technique enables the direct printing of complicated patterns, especially those with different or gradient grayscale distributions. By printing with appropriate patterns on one or both surfaces of the hydrogel sheets, many complex 3D shapes are obtained from the shape deformations upon swelling/deswelling, such as protuberant hexagon with sexfoil patterns, ding, blooming flower, and non-Euclidean plate shapes.
  PubDate: 2017-07-17T07:16:22.730775-05:
  DOI: 10.1002/adfm.201701962
Conjugated Small Molecule for Efficient Hole Transport in High-Performance
p-i-n Type Perovskite Solar Cells
- Authors: Liyan Yang; Feilong Cai, Yu Yan, Jinghai Li, Dan Liu, Andrew J. Pearson, Tao Wang
  Abstract: The π-conjugated organic small molecule 4,4′-cyclohexylidenebis[N,N-bis(4-methylphenyl) benzenamine] (TAPC) has been explored as an efficient hole transport material to replace poly(3,4-ethylenedio-xythiophene):poly(styrenesulfonate) (PEDOT:PSS) in the preparation of p-i-n type CH3NH3PbI3 perovskite solar cells. Smooth, uniform, and hydrophobic TAPC hole transport layers can be facilely deposited through solution casting without the need for any dopants. The power conversion efficiency of perovskite solar cells shows very weak TAPC layer thickness dependence across the range from 5 to 90 nm. Thermal annealing enables improved hole conductivity and efficient charge transport through an increase in TAPC crystallinity. The perovskite photoactive layer cast onto thermally annealed TAPC displays large grains and low residual PbI2, leading to a high charge recombination resistance. After optimization, a stabilized power conversion efficiency of 18.80% is achieved with marginal hysteresis, much higher than the value of 12.90% achieved using PEDOT:PSS. The TAPC-based devices also demonstrate superior stability compared with the PEDOT:PSS-based devices when stored in ambient circumstances, with a relatively high humidity ranging from 50 to 85%.Conjugated molecule 4,4′-cyclohexylidenebis[N,N-bis(4-methylphenyl) benzenamine] (TAPC) has been explored to replace poly(3,4-ethylenedio-xythiophene):poly(styrenesulfonate) in perovskite solar cells. The CH3NH3PbI3 solar cells are hysteresis-free, with marginal dependence on the thickness of TAPC, and achieve a power conversion efficiency of 18.8 over 12.9% as a result of increased Jsc, Voc, and fill factor.
  PubDate: 2017-07-17T07:15:46.26835-05:0
  DOI: 10.1002/adfm.201702613
Two Regioisomeric π-Conjugated Small Molecules: Synthesis, Photophysical,
Packing, and Optoelectronic Properties
- Authors: Yuxiang Li; Dae Hee Lee, Joungphil Lee, Thanh Luan Nguyen, Sungu Hwang, Moon Jeong Park, Dong Hoon Choi, Han Young Woo
  Abstract: Two regioisomeric D1-A-D-A-D1 type π-conjugated molecules (1,4-bis{5-[4-(5-fluoro-7-(5-hexylthiophen-2-yl)benzo[c][1,2,5]thiadiazole)]thiophen-2-yl}-2,5-bis(hexyldecyloxy)benzene (Prox-FBT) and 1,4-bis{5-[4-(6-fluoro-7-(5-hexylthiophen-2-yl)benzo[c][1,2,5]thiadiazole)]thiophen-2-yl}-2,5-bis(hexyldecyloxy)benzene (Dis-FBT)) are synthesized, by controlling the fluorine topology to be proximal or distal relative to the central core. The different F geometries are confirmed by the 1H–1H nuclear Overhauer effect spectroscopy (NOESY). Clearly different optical, electrochemical, and thermal transition behaviors are obtained, i.e., stronger absorption, deeper valance band (by ≈0.2 eV), and higher melting/recrystallization temperatures (by 7–20 °C) are observed for Dis-FBT. The different intermolecular packing and unit cell structures are also calculated for the two regioisomers, based on the powder X-ray diffraction and 2D grazing-incidence wide-angle X-ray diffraction measurements. A tighter π–π packing with a preferential monoclinic face-on orientation is extracted for Dis-FBT, compared to Prox-FBT with bimodal orientations. Different topological structures significantly affect the electrical and photovoltaic properties, where Prox-FBT shows higher parallel hole mobility (2.3 × 10−3 cm2 V−1 s−1), but Dis-FBT demonstrates higher power conversion efficiency (5.47%) with a larger open-circuit voltage of 0.95 V (vs 0.79 V for Prox-FBT). The findings suggest that small changes in the topological geometry can affect the electronic structure as well as self-assembly behaviors, which can possibly be utilized for fine-adjusting the electrical properties and further optimization of optoelectronic devices.Two regioisomeric π-conjugated molecules (1,4-bis{5-[4-(5-fluoro-7-(5-hexylthiophen-2-yl)benzo[c][1,2,5]thiadiazole)]thiophen-2-yl}-2,5-bis(hexyldecyloxy)benzene and 1,4-bis{5-[4-(6-fluoro-7-(5-hexylthiophen-2-yl)benzo[c][1,2,5]thiadiazole)]thiophen-2-yl}-2,5-bis(hexyldecyloxy)benzene) with different fluorine topologies (referred to as proximal or distal relative to central core) are synthesized, and the correlation between the topological geometry of fluorine atoms and optoelectronic property is examined in terms of the molecular structure, intermolecular interactions, and the resulting bulk morphology.
  PubDate: 2017-07-17T01:38:45.852196-05:
  DOI: 10.1002/adfm.201701942
Highly Elastic, Transparent, and Conductive 3D-Printed Ionic Composite
Hydrogels
- Authors: Jérémy Odent; Thomas J. Wallin, Wenyang Pan, Kevin Kruemplestaedter, Robert F. Shepherd, Emmanuel P. Giannelis
  Abstract: Despite extensive progress to engineer hydrogels for a broad range of technologies, practical applications have remained elusive due to their (until recently) poor mechanical properties and lack of fabrication approaches, which constrain active structures to simple geometries. This study demonstrates a family of ionic composite hydrogels with excellent mechanical properties that can be rapidly 3D-printed at high resolution using commercial stereolithography technology. The new material design leverages the dynamic and reversible nature of ionic interactions present in the system with the reinforcement ability of nanoparticles. The composite hydrogels combine within a single platform tunable stiffness, toughness, extensibility, and resiliency behavior not reported previously in other engineered hydrogels. In addition to their excellent mechanical performance, the ionic composites exhibit fast gelling under near-UV exposure, remarkable conductivity, and fast osmotically driven actuation. The design of such ionic composites, which combine a range of tunable properties and can be readily 3D-printed into complex architectures, provides opportunities for a variety of practical applications such as artificial tissue, soft actuators, compliant conductors, and sensors for soft robotics.A new family of ionic composite hydrogels that leverage the dynamic and reversible nature of electrostatic interactions between ammonium-containing polyacrylamide hydrogels and surface-modified sulfonated silica nanoparticles are rapidly 3D-printed at high resolution using commercial stereolithography technology. When fabricated, the composites are optically transparent, recover from repeatable extensive deformation, and act as truly 3D-compliant ionic conductors and large osmotically driven actuators.
  PubDate: 2017-07-17T01:38:11.676392-05:
  DOI: 10.1002/adfm.201701807
Precise Manipulation of Multilength Scale Morphology and Its Influence on
Eco-Friendly Printed All-Polymer Solar Cells
- Authors: Long Ye; Yuan Xiong, Sunsun Li, Masoud Ghasemi, Nrup Balar, Johnathan Turner, Abay Gadisa, Jianhui Hou, Brendan T. O'Connor, Harald Ade
  Abstract: Significant efforts have lead to demonstrations of nonfullerene solar cells (NFSCs) with record power conversion efficiency up to ≈13% for polymer:small molecule blends and ≈9% for all-polymer blends. However, the control of morphology in NFSCs based on polymer blends is very challenging and a key obstacle to pushing this technology to eventual commercialization. The relations between phases at various length scales and photovoltaic parameters of all-polymer bulk-heterojunctions remain poorly understood and seldom explored. Here, precise control over a multilength scale morphology and photovoltaic performance are demonstrated by simply altering the concentration of a green solvent additive used in blade-coated films. Resonant soft X-ray scattering is used to elucidate the multiphasic morphology of these printed all-polymeric films and complements with the use of grazing incidence wide-angle X-ray scattering and in situ spectroscopic ellipsometry characterizations to correlate the morphology parameters at different length scales to the device performance metrics. Benefiting from the highest relative volume fraction of small domains, additive-free solar cells show the best device performance, strengthening the advantage of single benign solvent approach. This study also highlights the importance of high volume fraction of smallest domains in printed NFSCs and organic solar cells in general.Precise control over the multilength scale morphology of printed all-polymer photovoltaic films by altering the concentration of a green additive is demonstrated by means of resonant soft X-ray scattering, in situ spectroscopic ellipsometry, and complementary methods. Additive-free nonfullerene devices show the best device performance due to the highest relative volume fraction of small domains and minimized length scale of large domains.
  PubDate: 2017-07-17T01:36:17.17334-05:0
  DOI: 10.1002/adfm.201702016
Bioinspired Spiky Micromotors Based on Sporopollenin Exine Capsules
- Authors: Hong Wang; Michael G. Potroz, Joshua A. Jackman, Bahareh Khezri, Tijana Marić, Nam-Joon Cho, Martin Pumera
  Abstract: The development of a micromotor with unique spiky morphology based on sporopollenin exine capsules (SECs) is reported here. A widely abundant natural material extracted from sunflower pollen grains, the SECs are physically robust, highly monodisperse microcapsules that are ornamented with spiky appendages, opening the door to exploring bubble generation on this unique biomaterial surface. Partial platinum coating on the SEC surface enables catalytic decomposition of hydrogen peroxide that leads to bubble-propelled motion of individual SECs. Moreover, the hollow capsule architecture provides a large internal cavity for macromolecular encapsulation, as demonstrated here by the loading and transport of bovine serum albumin. Taking advantage of the sporopollenin biopolymer's capacity for heavy metal binding, it is further demonstrated that fluid mixing induced by the motion and bubble generation of the SEC micromotors dramatically improves heavy metal binding and removal. The bioinspired micromotors combine the advantageous properties of SECs with autonomous motion ability, resulting in a multifunctional platform for drug delivery and water purification applications.A micromotor with unique spiky morphology based on the sporopollenin exine capsules (SECs) is developed. Derived from sunflower pollen grains, SECs are highly monodisperse microcapsules ornamented with spikes, which are capable of encapsulating macromolecules and binding with heavy metals. Bubble generation on the spiky surface leads to the propulsion of SEC micromotors for cargo transport and dynamic decontamination.
  PubDate: 2017-07-14T00:34:07.839511-05:
  DOI: 10.1002/adfm.201702338
Spatial Analysis of Metal–PLGA Hybrid Microstructures Using 3D SERS
Imaging
- Authors: Malte S. Strozyk; Dorleta Jimenez de Aberasturi, Jason V. Gregory, Mathias Brust, Joerg Lahann, Luis M. Liz-Marzán
  Abstract: The incorporation of gold nanoparticles in biodegradable polymeric nanostructures with controlled shape and size is of interest toward different applications in nanomedicine. Properties of the polymer such as drug loading and antibody functionalization can be combined with the plasmonic properties of gold nanoparticles, to yield advanced hybrid materials. This study presents a new way to synthesize multicompartmental microgels, fibers, or cylinders, with embedded anisotropic gold nanoparticles. Gold nanoparticles dispersed in an organic solvent can be embedded within the poly(lactic-co-glycolic acid) (PLGA) matrix of polymeric microstructures, when prepared via electrohydrodynamic co-jetting. Prior functionalization of the plasmonic nanoparticles with Raman active molecules allows for imaging of the nanocomposites by surface-enhanced Raman scattering (SERS) microscopy, thereby revealing nanoparticle distribution and photostability. These exceptionally stable hybrid materials, when used in combination with 3D SERS microscopy, offer new opportunities for bioimaging, in particular when long-term monitoring is required.A universal way for the implementation of metal nanoparticles intopoly(lactic-co-glycolic acid)microstructures via the electrohydrodynamic co-jetting process is presented. Metal nanoparticles of different shape and size are embedded into multicompartmental fluorescent microstructures. Their spatial distribution is analyzed using 3D surface-enhanced Raman scattering and confocal fluorescence microscopy.
  PubDate: 2017-07-14T00:33:21.029201-05:
  DOI: 10.1002/adfm.201701626
D-A1-D-A2 Backbone Strategy for Benzobisthiadiazole Based n-Channel
Organic Transistors: Clarifying the Selenium-Substitution Effect on the
Molecular Packing and Charge Transport Properties in Electron-Deficient
Polymers
- Authors: Yang Wang; Tsukasa Hasegawa, Hidetoshi Matsumoto, Takehiko Mori, Tsuyoshi Michinobu
  Abstract: Unipolar n-type semiconducting polymers based on the benzobisthiadiazole (BBT) unit and its heteroatom-substituted derivatives are for the first time synthesized by the D-A1-D-A2 polymer-backbone design strategy. Selenium (Se) substitution is a very effective molecular design, but it has been seldom studied in n-type polymers. In this study, within the similar conjugated framework, the Se substitution effects on the optical, electrochemical, solid-state polymer packing, electron mobility, and air-stability of the target unipolar n-type polymers are unraveled. Replacing the sulfur (S) atom in the thiadiazole heterocycles with the Se atom leads to narrower bandgaps and deeper lowest unoccupied molecular orbital (LUMO) levels of the n-type polymers. Furthermore, the Se-substituted polymer (pSeN-NDI) shows shorter lamellar packing distances and stronger edge-on π–π stacking interactions than its S-counterpart (pSN-NDI), as observed by the two-dimensional grazing-incidence wide-angle X-ray scattering (GIWAXS) patterns. With the deeper LUMO level and thin-film microstructures suitable for transistors, pSeN-NDI exhibits four-fold higher electron mobilities (μe) than pSN-NDI. However, the other Se-containing polymer, pSeS-NDI, forms rather amorphous film structures, which is caused by its limited thermal stability and decomposition during the thermal annealing processes, thus giving rise to a lower μe than its S-counterpart (pBBT-NDI). Most importantly, pBBT-NDI demonstrates an electron mobility of 0.039 cm2 V−1 s−1, which is noticeable among the unipolar n-type polymers based on the BBT and its analogs.The D-A1-D-A1 backbone strategy of coupling benzobisthiadiazole (BBT) analogues with another strong acceptor to achieve new n-type semiconducting polymers is reported. Selenium-substitution effects on the molecular packing and electron transport are unraveled. An electron mobility of 0.039 cm2 V−1 s−1 is shown, which is noticeable among the unipolar n-type polymers based on BBT and its analogs.
  PubDate: 2017-07-14T00:32:56.799316-05:
  DOI: 10.1002/adfm.201701486
Energy Saving Electrochromic Polymer Windows with a Highly Transparent
Charge-Balancing Layer
- Authors: Younghoon Kim; Haijin Shin, Minsu Han, Seogjae Seo, Woojae Lee, Jongbeom Na, Chihyun Park, Eunkyoung Kim
  Abstract: Highly transparent TiO2 nanoparticles are explored as a non-electrochromic (non-EC) charge-balancing layer for a high color contrast, bistable electrochromic window (ECW). The TiO2 nanoparticle (TNP) layer increases the potential at the EC polymer electrode, thereby lowering the working voltage of the ECW. This leads to lower the power consumption of ECWs without loss in the high color contrast (ΔT> 72%) and to remarkably improve the cyclability (ΔT change
  PubDate: 2017-07-14T00:32:23.582688-05:
  DOI: 10.1002/adfm.201701192
Novel Core–Shell FeOF/Ni(OH)2 Hierarchical Nanostructure for
All-Solid-State Flexible Supercapacitors with Enhanced Performance
- Authors: Mengqiao Wang; Zhaoqiang Li, Chengxiang Wang, Ruizheng Zhao, Caixia Li, Dexiang Guo, Luyuan Zhang, Longwei Yin
  Abstract: Well-controlled core–shell hierarchical nanostructures based on oxyfluoride and hydroxide are for the first time rationally designed and synthesized via a simple solvothermal and chemical precipitation route, in which FeOF nanorod acts as core and porous Ni(OH)2 nanosheets as shell. When evaluated as electrodes for supercapacitors, a high specific capacitance of 1452 F g−1 can be obtained at a current density of 1 A g−1. Even as the current density increases to 10 A g−1, the core–shell hybrid still reserves a noticeable capacitance of 1060 F g−1, showing an excellent rate capacity. Furthermore, all-solid-state flexible asymmetric supercapacitor based on the FeOF/Ni(OH)2 hybrid as a positive electrode and activated carbon as a negative electrode shows high power density, high energy density, and long cycling lifespan. The excellent electrochemical performance of the FeOF/Ni(OH)2 core–shell hybrid is ascribed to the unique microstructure and synergistic effects. FeOF nanorod from FeF3 by partial substitution of fluorine with oxygen behaves as a low intrinsic resistance, thus facilitating charge transfer processes. While the hierarchical Ni(OH)2 nanosheets with large surface area provide enough active sites for redox chemical reactions, leading to greatly enhanced electrochemical activity. The well-controllable oxyfluoride/hydroxide hybrid is inspiring, opening up a new way to design new electrodes for next-generation all-solid-state supercapacitors.Well-controlled core–shell hierarchical FeOF/Ni(OH)2 hybrids based on oxyfluoride and hydroxide are rationally designed via a simple route. FeOF nanorod facilitates the charge transfer process; hierarchical Ni(OH)2 nanosheets with large surface area provide enough active sites for redox chemical reactions. All-solid-state flexible asymmetric supercapacitor based on FeOF/Ni(OH)2 hybrid and activated-carbon shows high power density, high energy density, and long cycling lifespan.
  PubDate: 2017-07-14T00:26:11.998883-05:
  DOI: 10.1002/adfm.201701014
Voltage-Induced Coercivity Reduction in Nanoporous Alloy Films: A Boost
toward Energy-Efficient Magnetic Actuation
- Authors: Alberto Quintana; Jin Zhang, Eloy Isarain-Chávez, Enric Menéndez, Ramón Cuadrado, Roberto Robles, Maria Dolors Baró, Miguel Guerrero, Salvador Pané, Bradley J. Nelson, Carlos Maria Müller, Pablo Ordejón, Josep Nogués, Eva Pellicer, Jordi Sort
  Abstract: Magnetic data storage and magnetically actuated devices are conventionally controlled by magnetic fields generated using electric currents. This involves significant power dissipation by Joule heating effect. To optimize energy efficiency, manipulation of magnetic information with lower magnetic fields (i.e., lower electric currents) is desirable. This can be accomplished by reducing the coercivity of the actuated material. Here, a drastic reduction of coercivity is observed at room temperature in thick (≈600 nm), nanoporous, electrodeposited Cu–Ni films by simply subjecting them to the action of an electric field. The effect is due to voltage-induced changes in the magnetic anisotropy. The large surface-area-to-volume ratio and the ultranarrow pore walls of the system allow the whole film, and not only the topmost surface, to effectively contribute to the observed magnetoelectric effect. This waives the stringent “ultrathin-film requirement” from previous studies, where small voltage-driven coercivity variations were reported. This observation expands the already wide range of applications of nanoporous materials (hitherto in areas like energy storage or catalysis) and it opens new paradigms in the fields of spintronics, computation, and magnetic actuation in general.A novel effect in nanoporous magnetic films is demonstrated: the possibility to drastically reduce their coercivity under the action of an electric field, by simply applying continuous voltage. The reduction of coercivity with voltage implies that lower currents are needed to switch the magnetization of the system, thus considerably reducing heat dissipation and enhancing energy efficiency during magnetic actuation.
  PubDate: 2017-07-13T00:26:29.26536-05:0
  DOI: 10.1002/adfm.201701904
Combination of Surface Charge and Size Controls the Cellular Uptake of
Functionalized Graphene Sheets
- Authors: Zhaoxu Tu; Katharina Achazi, Andrea Schulz, Rolf Mülhaupt, Steffen Thierbach, Eckart Rühl, Mohsen Adeli, Rainer Haag
  Abstract: A fundamental issue for biomedical applications of graphene is the correlation between its physicochemical properties and cellular uptake mechanism. However, such studies are challenging due to the intrinsic polydispersity of graphene. In this work, a series of water soluble graphene sheets with the same polymer coverage, density of functional groups, and fluorescence intensity but three different sizes and surface charges are produced. The effect of the latter two factors and their combination on the mechanism of cellular uptake and intracellular pathways of these defined nanosheets is investigated via confocal and Raman microscopies. While positively (NH3+) and negatively (OSO3−) charged sheets show an energy dependent uptake, their neutral analogs do not show any significant uptake. The cellular uptake efficacy of positively charged graphene sheets is independent of the size and occurs both through phagocytosis and clathrin-mediated endocytosis pathways. However, cellular uptake efficacy of graphene sheets with negative surface charge strongly depends on the size of the sheets. They cross the membrane mainly through phagocytosis and sulfate-receptor-mediated endocytosis. This study demonstrates that the impact of the size of graphene derivatives on their cellular uptake pathways highly depends on their surface charges and vice versa.A family of graphene derivatives with defined polymer coverage, density of functional groups, fluorescence intensity, surface charge and size are synthesized and their cellular uptake is investigated. It is found that the combination of size and surface charge plays a pivotal role in the cellular uptake pathways of these graphene derivatives.
  PubDate: 2017-07-10T13:19:17.313083-05:
  DOI: 10.1002/adfm.201701837
[4]Helicene–Squalene Fluorescent Nanoassemblies for Specific Targeting
of Mitochondria in Live-Cell Imaging
- Authors: Andrej Babič; Simon Pascal, Romain Duwald, Dimitri Moreau, Jérôme Lacour, Eric Allémann
  Abstract: Ester, amide, and directly linked composites of squalene and cationic diaza [4]helicenes 1 are readily prepared. These lipid-dye constructs 2, 3, and 4 give in aqueous media monodispersed spherical nanoassemblies around 100–130 nm in diameter with excellent stability for several months. Racemic and enantiopure nanoassemblies of compound 2 are fully characterized, including by transmission electron microscope and cryogenic transmission electron microscope imaging that did not reveal higher order supramolecular structures. Investigations of their (chir)optical properties show red absorption maxima ≈600 nm and red fluorescence spanning up to the near-infrared region, with average Stokes shifts of 1350–1550 cm−1. Live-cell imaging by confocal microscopy reveals rapid internalization on the minute time scale and organelle-specific accumulation. Colocalization with MitoTracker in several cancer cell lines demonstrates a specific staining of mitochondria by the [4]helicene–squalene nanoassemblies. To our knowledge, it is the first report of a subcellular targeting by squalene-based nanoassemblies.[4]helicene–squalene constructs form fluorescent self-assemblies in aqueous media. Monodisperse spherical supramolecular nanoassemblies display impressive far-red fluorescence and specific mitochondrial targeting in several cancer cells. This is achieved through precise building block architecture and proves their potential as subcellular targeting nanoplatform.
  PubDate: 2017-07-10T13:17:47.810753-05:
  DOI: 10.1002/adfm.201701839
All-Layered 2D Optoelectronics: A High-Performance UV–vis–NIR
- Authors: Jiandong Yao; Zhaoqiang Zheng, Guowei Yang
  Abstract: Nanoelectronics is in urgent demand of exceptional device architecture with ultrathin thickness below 10 nm and dangling-bond-free surface to break through current physical bottleneck and achieve new record of integration level. The advance in 2D van der Waals materials endows scientists with new accessibility. This study reports an all-layered 2D Bi2Te3-SnSe-Bi2Te3 photodetector, and the broadband photoresponse of the device from ultraviolet (370 nm) to near-infrared (808 nm) is demonstrated. In addition, the optimized responsivity reaches 5.5 A W−1, with the corresponding eternal quantum efficiency of 1833% and detectivity of 6 × 1010 cm Hz1/2 W−1. These figures-of-merits are among the best values of the reported all-layered 2D photodetectors, which are several orders of magnitude higher than those of the previous SnSe photodetectors. The superior device performance is attributed to the synergy of highly conductive surface state of Bi2Te3 topological insulator, perfect band alignment between Bi2Te3 and SnSe as well as small interface potential fluctuation. Meanwhile, the all-layered 2D device is further constructed onto flexible mica substrate and its photoresponse is maintained roughly unchanged upon 60 bending cycles. The findings represent a fundamental scenario for advancement of the next generation high performance and high integration level flexible optoelectronics.An all-layered ultrathin Bi2Te3-SnSe-Bi2Te3 photodetector (
  PubDate: 2017-07-10T13:16:56.965056-05:
  DOI: 10.1002/adfm.201701823
Dual-Targeting to Cancer Cells and M2 Macrophages via Biomimetic Delivery
of Mannosylated Albumin Nanoparticles for Drug-Resistant Cancer Therapy
- Authors: Pengfei Zhao; Weimin Yin, Aihua Wu, Yisi Tang, Jinyu Wang, Zhenzhen Pan, Tingting Lin, Meng Zhang, Binfan Chen, Yifei Duan, Yongzhuo Huang
  Abstract: Multidrug resistance (MDR) is an issue that is not only related to cancer cells but also associated with the tumor microenvironments. MDR involves the complicated cancer cellular events and the crosstalk between cancer cells and their surroundings. Ideally, an effective system against MDR cancer should take dual action on both cancer cells and tumor microenvironments. The authors find that both the drug-resistant colon cancer cells and the protumor M2 macrophages highly express two nutrient transporters, i.e., secreted protein acidic and rich in cysteine (SPARC) and mannose receptors (MR). By targeting SPARC and MR, a system can act on both cancer cells and M2 macrophages. Herein the authors develop a mannosylated albumin nanoparticles with coencapsulation of different drugs, i.e., disulfiram/copper complex (DSF/Cu) and regorafenib (Rego). The results show that combination therapy of DSF/Cu and Rego efficiently inhibits the growth of drug-resistant colon tumor, and the combination has not been reported yet for use in anticancer treatment. The system significantly improves the treatment outcomes in the animal model bearing drug-resistant tumors. The therapeutic mechanisms involve enhanced apoptosis, upregulation of intracellular ROS, anti-angiogenesis, and tumor-associated macrophage “re-education.” This strategy is characterized by dual targeting to and the simultaneous action on cancer cells and M2 macrophages, with biomimetic codelivery of a novel drug combination.Multidrug resistance (MDR) is a complex of various events involving not only the cancer cells but also their surroundings (tumor microenvironments). The authors develop the “one stone two birds” strategy to overcome MDR by using a mannosylated albumin nanoparticulate codelivery system to dual-target the cancer cells and M2 macrophages, both of which overexpress mannose receptors and the albumin-binding protein—secreted protein acidic and rich in cysteine.
  PubDate: 2017-07-10T13:16:38.693681-05:
  DOI: 10.1002/adfm.201700403
Assembly and Characterizations of Bifunctional Fluorescent and Magnetic
Microneedles With One Decade Length Tunability
- Authors: Jean-Baptiste Lugagne; Gwennhaël Brackx, Emek Seyrek, Sophie Nowak, Yann Sivry, Leticia Vitorazi, Jean-François Berret, Pascal Hersen, Gaëlle Charron
  Abstract: This report presents the fabrication of bifunctional magnetic and fluorescent microneedles (µNDs) made of a ternary mixture of magnetic nanoparticles (NPs), quantum dots (QDs), and polyelectrolyte. The assembly relies on the electrostatic complexation of negatively charged NPs with positively charged polymer strands and is controlled by the charge ratio between the nanoparticle building blocks and the polymer mortar. The resulting 1D objects can be actuated using an external magnetic field and can be imaged using fluorescence microscopy, thanks to the fluorescent and superparamagnetic properties inherited from their NP constituents. Using a combination of core and surface characterizations and a state-of-the-art image analysis algorithm, the dependence of the brightness and length on the ternary composition is thoroughly investigated. In particular, statistics on hundreds of µNDs with a range of compositions show that the µNDs have a log-lormal length distribution and that their mean length can be robustly tuned in the 5–50 µm range to match the relevant length scales of various applications in micromixing, bioassays or biomechanics.Bifunctional microneedles are assembled from magnetic nanoparticles, quantum dots, and polyelectrolyte using a straightforward protocol. The microneedles are both fluorescent and responsive under an external magnetic field and their mean length can be tuned from 5 to 50 µm by playing on the starting composition to match the needs of several applications.
  PubDate: 2017-07-10T13:15:10.492856-05:
  DOI: 10.1002/adfm.201700362
A Structurable Gel-Polymer Electrolyte for Sodium Ion Batteries
- Authors: Jin Il Kim; Yunah Choi, Kyung Yoon Chung, Jong Hyeok Park
  Abstract: In this work, a structurable gel-polymer electrolyte (SGPE) with a controllable pore structure that is not destroyed after immersion in an electrolyte is produced via a simple nonsolvent induced phase separation (NIPS) method. This study investigates how the regulation of the nonsolvent content affects the evolving nanomorphology of the composite separators and overcomes the drawbacks of conventional separators, such as glass fiber (GF), which has been widely used in sodium ion batteries (SIBs), through the regulation of pore size and gel-polymer position. The interfacial resistance is reduced through selective positioning of a poly(vinylidene fluoride-co-hexa fluoropropylene) (PVdF-HFP) gel-polymer with the aid of NIPS, which in turn enhances the compatibility between the electrolyte and electrode. In addition, the highly porous morphology of the GF/SGPE obtained via NIPS allows for the absorption of more liquid electrolyte. Thus, a greatly improved cell performance of the SIBs is observed when a tailored SGPE is incorporated into the GF separator through charge/discharge testing compared with the performance observed with pristine GF and conventional GF coated with PVdF-HFP gel-polymer.Structurable gel-polymer electrolyte with controllable pore morphology for better sodium ion transport exhibits superior interfacial adhesion and compatibility between electrode and electrolyte, resulting in enhanced C-rate and cycle performance without deformation of its structure.
  PubDate: 2017-07-10T13:13:21.067035-05:
  DOI: 10.1002/adfm.201701768
Metal Conductive Surface Patterning on Photoactive Polyimide
- Authors: Jing Liu; Minfeng Li, Yuzhao Yang, Lirong Xu, Jingjing Lin, Wei Hong, Xudong Chen
  Abstract: Current fabrication methods for metal interconnects and contacts are generally based on conventional photoresist fabrication procedures that require expensive equipment and multiple material/time-consuming steps. In this work, a photopatternable polyimide is synthesized via the copolymerization of a functional diamine monomer with a 1,4-dihydropyridine side-chain which can decompose under UV irradiation into a pyridine group—a promising ligand for palladium ions. After the absorption of palladium ions, the electroless copper plating is carried out to form metal patterns of copper. Copper patterns with smooth boundaries are confirmed by scanning electron microscope and atomic force microscope. Robust interfacial bonding between the copper and the polyimide film is evidenced by Scotch tape adhesion tests. The photopatternable polyimide has the advantages of low Pd consumption, easy operation without expansive equipment. The linear thermal expansion coefficient of the photopatternable polyimide remains close to the one of copper wire, demonstrating the adaptability of the photopatternable polyimide for integrated circuit application. This work presents the approach of (i) the synthesis of a novel photopatternable polyimide and (ii) its application for making flexible conductive metal structures and patterned metal interconnects, which can be expected to have tremendous potential in the field of flexible electronics.Photopatternable polyimide is developed for the low-cost patterning with flexible metal conductors via UV irradiation and electroless deposition at room temperature. Polyimide with highly conductive copper surface patterns displays excellent flexibility, a suitable thermal expansion coefficient, and strong interfacial bonding, which can be readily used for flexible integrated circuits and microelectronics.
  PubDate: 2017-07-10T10:58:52.413355-05:
  DOI: 10.1002/adfm.201701674
Biodegradable and Highly Deformable Temperature Sensors for the Internet
of Things
- Authors: Giovanni A. Salvatore; Jenny Sülzle, Filippo Dalla Valle, Giuseppe Cantarella, Francesco Robotti, Petar Jokic, Stefan Knobelspies, Alwin Daus, Lars Büthe, Luisa Petti, Norbert Kirchgessner, Raoul Hopf, Michele Magno, Gerhard Tröster
  Abstract: Recent advances in biomaterials, thin film processing, and nanofabrication offer the opportunity to design electronics with novel and unique capabilities, including high mechanical stability and biodegradation, which are relevant in medical implants, environmental sensors, and wearable and disposable devices. Combining reliable electrical performance with high mechanical deformation and chemical degradation remains still challenging. This work reports temperature sensors whose material composition enables full biodegradation while the layout and ultrathin format ensure a response time of 10 ms and stable operation demonstrated by a resistance variation of less than 0.7% when the devices are crumpled, folded, and stretched up to 10%. Magnesium microstructures are encapsulated by a compostable-certified flexible polymer which exhibits small swelling rate and a Young's modulus of about 500 MPa which approximates that of muscles and cartilage. The extension of the design from a single sensor to an array and its integration onto a fluidic device, made of the same polymer, provides routes for a smart biodegradable system for flow mapping. Proper packaging of the sensors tunes the dissolution dynamics to a few days in water while the connection to a Bluetooth module demonstrates wireless operation with 200 mK resolution prospecting application in food tracking and in medical postsurgery monitoring.Advances in biomaterials and nanofabrication allow designing highly mechanically stable electronics that are biodegradable. This study demonstrates temperature sensors whose material composition enables full biodegradation while the layout and ultrathin format ensure fast response time and reliable operations upon stretching and folding. Wireless operation, achieved via an external Bluetooth module, prospects application in food monitoring and post-surgery implants.
  PubDate: 2017-07-10T10:57:27.295409-05:
  DOI: 10.1002/adfm.201702390
Hydroxyl-Rich Polycation Brushed Multifunctional Rare-Earth-Gold
Core–Shell Nanorods for Versatile Therapy Platforms
- Authors: Lizhi Song; Nana Zhao, Fu-Jian Xu
  Abstract: It is of great significance to develop a multifunctional imaging-guided therapeutic platform with ideal resolution and sensitivity. Notably, rare-earth (RE) nanoparticles are attractive candidates for multimodal imaging due to their unique optical and magnetic properties. In this work, a rational design of hierarchical nanohybrids employing RE-Au hetero-nanostructures is proposed. 1D RE nanorods are adopted as the core to facilitate cellular internalization with the coating of gold nanoshells for photothermal performances. Hydroxyl-rich polycations with low cytotoxicity are grafted onto the surface of RE-Au to produce RE-Au-PGEA (ethanolamine-functionalized poly(glycidyl methacrylate)) nanohybrids with impressive gene transfection capability. Given the virtues of all the components, the feasibility of RE-Au-PGEA for multifunctional photoacoustic, computed tomography, magnetic resonance, upconversion luminescence imaging, and complementary photothermal therapy/gene therapy therapy is investigated in detail in vitro and in vivo. The visualization of the therapeutic processes with comprehensive information renders RE-Au-PGEA nanohybrid an intriguing platform to realize enhanced antitumor efficiency.Hierarchical hetero-nanostructures (rare-earth (RE)-Au-ethanolamine-functionalized poly(glycidyl methacrylate) (PGEA)) consisting of gold nanoshell-coated RE nanorods and hydroxyl-rich polycations are synthesized for versatile imaging-guided complementary cancer therapy.
  PubDate: 2017-07-07T07:12:39.680124-05:
  DOI: 10.1002/adfm.201701255
Ultrathin MoS2 Nanosheets@Metal Organic Framework-Derived N-Doped Carbon
Nanowall Arrays as Sodium Ion Battery Anode with Superior Cycling Life and
Rate Capability
- Authors: Weina Ren; Haifeng Zhang, Cao Guan, Chuanwei Cheng
  Abstract: This study reports the design and fabrication of ultrathin MoS2 nanosheets@metal organic framework-derived N-doped carbon nanowall array hybrids on flexible carbon cloth (CC@CN@MoS2) as a free-standing anode for high-performance sodium ion batteries. When evaluated as an anode for sodium ion battery, the as-fabricated CC@CN@MoS2 electrode exhibits a high capacity (653.9 mA h g−1 of the second cycle and 619.2 mA h g−1 after 100 cycles at 200 mA g−1), excellent rate capability, and long cycling life stability (265 mA h g−1 at 1 A g−1 after 1000 cycles). The excellent electrochemical performance can be attributed to the unique 2D hybrid structures, in which the ultrathin MoS2 nanosheets with expanded interlayers can provide shortened ion diffusion paths and favorable Na+ insertion/extraction space, and the porous N-doped carbon nanowall arrays on flexible carbon cloth are able to improve the conductivity and maintain the structural integrity. Moreover, the N-doping-induced defects also make them favorable for the effective storage of sodium ions, which enables the enhanced capacity and rate performance of MoS2.A unique 2D MoS2 nanosheets@N-doped carbon nanowall hybrid structure on carbon cloth is fabricated and utilized as an efficient anode for high-performance sodium ion batteries.
  PubDate: 2017-07-07T07:11:12.914877-05:
  DOI: 10.1002/adfm.201702116
MUC1 Aptamer Targeted SERS Nanoprobes
- Authors: Suchetan Pal; Stefan Harmsen, Anton Oseledchyk, Hsiao-Ting Hsu, Moritz F. Kircher
  Abstract: Recently, surface-enhanced Raman scattering (SERS) nanoprobes (NPs) have shown promise in the field of cancer imaging due to their unparalleled signal specificity and high sensitivity. This study reports the development of a DNA aptamer targeted SERS NP. Recently, aptamers are being investigated as a viable alternative to more traditional antibody targeting due to their low immunogenicity and low cost of production. A strategy is developed to functionalize SERS NPs with DNA aptamers, which target Mucin1 (MUC1) in human breast cancer (BC). Thorough in vitro characterization studies demonstrate excellent serum stability and specific binding of the targeted NPs to MUC1. In order to test their in vivo targeting capability, MUC1-targeted SERS NPs are coinjected with nontargeted or blocked MUC1-targeted SERS NPs in BC xenograft mouse models. A two-tumor mouse model with differential expression of MUC1 (MDA-MB-468 and MDA-MB-453) is used to control for active versus passive targeting in the same animals. The results show that the targeted SERS NPs home to the tumors via active targeting of MUC1, with low levels of passive targeting. This strategy is expected to be an advantageous alternative to antibody-based targeting and useful for targeted imaging of tumor extent, progression, and therapeutic response.A mucin1 (MUC1) DNA aptamer targeted surface-enhanced Raman scattering (SERS) nanoparticle is developed by surface functionalization of SERS nanoparticles. These nanoparticles are optically and structurally stable in biological fluid and target MUC1 overexpressing breast cancer cells in vitro. By coinjection with a nontargeted nanoparticle, this study shows that the MUC1 aptamer targeted nanoparticles home specifically to MUC1 overexpressing tumor tissue in vivo.
  PubDate: 2017-07-06T07:13:41.266772-05:
  DOI: 10.1002/adfm.201606632
Wide Field Magnetic Luminescence Imaging
- Authors: Matthew P. P. Hodges; Martin Grell, Nicola A. Morley, Dan A. Allwood
  Abstract: This study demonstrates how magnetic-field-dependent luminescence from organic films can be used to image the magnetic configuration of an underlying sample. The organic semiconductors tetracene and rubrene exhibit singlet exciton fission, which is a process sensitive to magnetic fields. Here, thin films of these materials were characterized using photoluminescence spectrometry, atomic force microscopy, and photoluminescence magnetometry. The luminescence from these substrate-bound thin films is imaged to reveal the magnetic configuration of underlying Nd-Fe-B magnets. The tendency of rubrene to form amorphous films and produce large changes in photoluminescence under an applied magnetic field makes it more appropriate for magnetic field imaging than tetracene. This demonstration can be extended in the future to allow simple microscopic imaging of magnetic structure.A magnetic imaging technique is demonstrated that uses tetracene and rubrene thin films to probe the magnetic stray fields of macroscopic permanent magnets via steady-state photoluminescence at room temperature. This technique exploits singlet exciton fission to produce quantitative images. This proof of concept has the potential to be extended in the future to allow simple microscopic magnetic imaging.
  PubDate: 2017-07-06T07:12:50.971125-05:
  DOI: 10.1002/adfm.201606613
A Matter of Size and Stress: Understanding the First-Order Transition in
Materials for Solid-State Refrigeration
- Authors: Tino Gottschall; Dimitri Benke, Maximilian Fries, Andreas Taubel, Iliya A. Radulov, Konstantin P. Skokov, Oliver Gutfleisch
  Abstract: Solid-state magnetic refrigeration is a high-potential, resource-efficient cooling technology. However, many challenges involving materials science and engineering need to be overcome to achieve an industry-ready technology. Caloric materials with a first-order transition—associated with a large volume expansion or contraction—appear to be the most promising because of their large adiabatic temperature and isothermal entropy changes. In this study, using experiment and simulation, it is demonstrated with the most promising magnetocaloric candidate materials, La–Fe–Si, Mn–Fe–P–Si, and Ni–Mn–In–Co, that the characteristics of the first-order transition are fundamentally determined by the evolution of mechanical stresses. This phenomenon is referred to as the stress-coupling mechanism. Furthermore, its applicability goes beyond magnetocaloric materials, since it describes the first-order transitions in multicaloric materials as well.Solid-state magnetic refrigeration is a high-potential cooling technology. Materials with a first-order transition are most promising because of their large adiabatic temperature and isothermal entropy changes. In this study, it is demonstrated with the magnetocaloric materials La–Fe–Si, Mn–Fe–P–Si, and Ni–Mn–In–Co, using experiment and simulation, that the characteristics of the first-order transition are fundamentally determined by the evolution of mechanical stresses.
  PubDate: 2017-07-06T07:10:42.780186-05:
  DOI: 10.1002/adfm.201606735
Flexible Filter-Free Narrowband Photodetector with High Gain and
Customized Responsive Spectrum
- Authors: Liang Gao; Cong Ge, Wenhui Li, Chuancheng Jia, Kai Zeng, Weicheng Pan, Haodi Wu, Yang Zhao, Yisu He, Jungang He, Zhixin Zhao, Guangda Niu, Xuefeng Guo, F. Pelayo Garcia de Arquer, Edward H. Sargent, Jiang Tang
  Abstract: Conventional narrowband photodetection is enabled by coupling broadband photodetectors with complex optical filters. The recently reported charge collection narrowing, an alternative filter-free strategy, attains very narrowband photodetection at the sacrifice of sensitivity. Herein, a new strategy is proposed to customize the responsive spectrum with high gain by using dye molecules with intrinsically versatile and narrowband absorption. The device configuration is organic dye/Zn0.9Mg0.1O nanoparticles/graphene, where the organic dye serves as the narrowband absorber, graphene serves as the fast carrier transport channel, and Zn0.9Mg0.1O nanoparticles play a triple role of enhancing dye loading, suppressing dye aggregation and blocking charge back recombination. A high responsivity of 8 × 103 A W−1 is thus obtained at a 530 nm response peak with a 60 nm full-width at half maximum, a four orders of magnitude increase in sensitivity compared to the best narrowband photodetectors reported to date under the comparable electric field. Organic dyes with dual-band absorption to demonstrate narrowband photodetectors with customized responsive spectrum are further implemented. The approach opens the way to the realization of efficient flexible narrowband photodetection for electronic skin and wearable electronic applications.A new strategy, combining intrinsically narrowband absorption of dye molecules with the support of the Zn0.9Mg0.1O nanoparticles and high conductivity of graphene, achieves flexible filter-free narrowband photodetection with unprecedented responsivity (external quantum efficiency) and a customized responsive spectrum.
  PubDate: 2017-07-06T07:06:12.161043-05:
  DOI: 10.1002/adfm.201702360
Electrochromically and Photochromically Controllable Multifunctional
OligoEDOT Derivatives
- Authors: Satoshi Matsushita; Yong Soo Jeong, Yoshinori Okada, Hiroyuki Hayasaka, Kazuo Akagi
  Abstract: Multifunctional conjugated co-oligomers with electrochromic and photochromic properties are synthesized by a cross-coupling polycondensation reaction between bis(trialkylstannyl)-3,4-ethylenedioxythiophene and a phenylene or thienylene derivative bearing a photoresponsive dithienylethene (DE) moiety. The oligomer exhibits a reversible change between the neutral and oxidized states of the main chain upon electrochemical doping and dedoping. Furthermore, the oligomer shows reversible photoisomerization between the open and closed forms of the DE group in the side chain upon irradiation with ultraviolet and visible light. As a consequence, the oligomers possess various electronic structures that show cyclically reversible changes via the electrochemical doping and dedoping, and photoisomerization, producing four types of colored films in an oligomer system. Among the four types of electronic structures, only the dopant-free oligomer film with the open form of the DE group shows visible fluorescence. To the best of our knowledge, the present conjugated oligomers are the first to exhibit both electrochromic and photochromic functions with cyclical reversibility.Electrochromically and photochromically controllable multifunctional oligoEDOT (3,4-ethylenedioxythiophene) derivatives substituted with a photoresponsive dithienylethene moiety are synthesized. The cast films of the co-oligomers show electrochromism via the formation of neutral and oxidized forms of the main chain and simultaneously show photochromism via a ring-opening/closing isomerization reaction of the side chain triggered by photostimuli.
  PubDate: 2017-07-05T07:37:44.067148-05:
  DOI: 10.1002/adfm.201700929
Control of Switching Modes and Conductance Quantization in Oxygen
Engineered HfOx based Memristive Devices
- Authors: Sankaramangalam Ulhas Sharath; Stefan Vogel, Leopoldo Molina-Luna, Erwin Hildebrandt, Christian Wenger, Jose Kurian, Michael Duerrschnabel, Tore Niermann, Gang Niu, Pauline Calka, Michael Lehmann, Hans-Joachim Kleebe, Thomas Schroeder, Lambert Alff
  Abstract: Hafnium oxide (HfOx)-based memristive devices have tremendous potential as nonvolatile resistive random access memory (RRAM) and in neuromorphic electronics. Despite its seemingly simple two-terminal structure, a myriad of RRAM devices reported in the rapidly growing literature exhibit rather complex resistive switching behaviors. Using Pt/HfOx/TiN-based metal–insulator–metal structures as model systems, it is shown that a well-controlled oxygen stoichiometry governs the filament formation and the occurrence of multiple switching modes. The oxygen vacancy concentration is found to be the key factor in manipulating the balance between electric field and Joule heating during formation, rupture (reset), and reformation (set) of the conductive filaments in the dielectric. In addition, the engineering of oxygen vacancies stabilizes atomic size filament constrictions exhibiting integer and half-integer conductance quantization at room temperature during set and reset. Identifying the materials conditions of different switching modes and conductance quantization contributes to a unified switching model correlating structural and functional properties of RRAM materials. The possibility to engineer the oxygen stoichiometry in HfOx will allow creating quantum point contacts with multiple conductance quanta as a first step toward multilevel memristive quantum devices.Oxygen stoichiometry engineering is intrinsically achieved in hafnium-oxide-based memristive devices via reactive molecular beam epitaxy in a Pt/HfOx/TiN device configuration. This allows for uncovering the nature of complex coexistence of multiple switching modes (unipolar, bipolar, complementary, threshold) and occurrence of quantum conductance states. The findings are relevant to the control of switching dynamics in all oxide-based switching devices.
  PubDate: 2017-07-04T05:56:41.38324-05:0
  DOI: 10.1002/adfm.201700432
High-Performance Ultraviolet Photodetector Based on a Few-Layered 2D NiPS3
Nanosheet
- Authors: Junwei Chu; Fengmei Wang, Lei Yin, Le Lei, Chaoyi Yan, Feng Wang, Yao Wen, Zhenxing Wang, Chao Jiang, Liping Feng, Jie Xiong, Yanrong Li, Jun He
  Abstract: 2D materials, represented by transition metal dichalcogenides (TMDs), have attracted tremendous research interests in photoelectronic and electronic devices. However, for their relatively small bandgap (
  PubDate: 2017-07-04T05:55:42.548056-05:
  DOI: 10.1002/adfm.201701342
Enhanced Magnetocaloric Effect from Cr Substitution in Ising Lanthanide
Gallium Garnets Ln3CrGa4O12 (Ln = Tb, Dy, Ho)
- Authors: Paromita Mukherjee; Siân E. Dutton
  Abstract: A detailed study on the crystal structure and bulk magnetic properties of Cr substituted Ising type lanthanide gallium garnets Ln3CrGa4O12 (Ln = Tb, Dy, Ho) is carried out using room temperature powder X-ray and neutron diffraction, magnetic susceptibility, isothermal magnetization, and heat capacity measurements. The magnetocaloric effect (MCE) in Ln3CrGa4O12 is compared to that of Ln3Ga5O12. In lower magnetic fields attainable by a permanent magnet (≤ 2 T), Cr substitution greatly enhances the MCE - by 20% for Ln = Dy and 120% for Ln = Ho compared to the unsubstituted Ln3Ga5O12. This is likely due to changes in the magnetic ground state as Cr substitution also significantly reduces the frustration in the magnetic lattice for the Ising type Ln3Ga5O12.The impact of Cr substitution on the magnetocaloric effect in Ising type lanthanide gallium garnets is discussed. A 20% increase for Ln = Dy and a 120% increase for Ln = Ho is observed in a field of 2 T. Cr substitution in the frustrated garnet lattice significantly reduces the magnetic frustration.
  PubDate: 2017-07-04T00:42:58.852798-05:
  DOI: 10.1002/adfm.201701950
Peptide-Based Nanostructured Materials with Intrinsic Proapoptotic
Activities in CXCR4+ Solid Tumors
- Authors: Naroa Serna; María Virtudes Céspedes, Laura Sánchez-García, Ugutz Unzueta, Rita Sala, Alejandro Sánchez-Chardi, Francisco Cortés, Neus Ferrer-Miralles, Ramón Mangues, Esther Vázquez, Antonio Villaverde
  Abstract: Protein materials are gaining interest in nanomedicine because of the unique combination of regulatable function and structure. A main application of protein nanoparticles is as vehicles for cell-targeted drug delivery in the form of nanoconjugates, in which a conventional or innovative drug is associated to a carrier protein. Here, a new nanomedical approach based on self-assembling protein nanoparticles is developed in which a chemically homogeneous protein material acts, simultaneously, as vehicle and drug. For that, three proapoptotic peptidic factors are engineered to self-assemble as protein-only, fully stable nanoparticles that escape renal clearance, for the multivalent display of a CXCR4 ligand and the intracellular delivery into CXCR4+ colorectal cancer models. These materials, produced and purified in a single step from bacterial cells, show an excellent biodistribution upon systemic administration and local antitumoral effects. The design and generation of intrinsically therapeutic protein-based materials offer unexpected opportunities in targeted drug delivery based on fully biocompatible, tailor-made constructs.A new category of biomaterials is developed in which therapeutic peptides self-assemble as intrinsically functional protein-only nanoparticles, acting as targeted drugs. Several unrelated tumor-targeted proapoptotic proteins are administered in cancer models in form of chemically homogenous assemblies, with a size over the threshold of renal clearance. These materials promote targeted apoptosis and necrosis in colorectal cancer tissues upon systemic administration.
  PubDate: 2017-07-04T00:42:40.232634-05:
  DOI: 10.1002/adfm.201700919
Rapid Photochemical Synthesis of Sea-Urchin-Shaped Hierarchical Porous
COF-5 and Its Lithography-Free Patterned Growth
- Authors: Soyoung Kim; Chibeom Park, Minkyung Lee, Intek Song, Jungah Kim, Minhui Lee, Jaehoon Jung, Yousoo Kim, Hyunseob Lim, Hee Cheul Choi
  Abstract: Despite potential advantages of covalent organic frameworks (COFs) in wide area applications, several limitations in conventional solvothermal synthesis, such as long reaction time and high reaction temperature, reduce reaction efficiency and prohibit technical processes for practical applications. Therefore, the development of a novel synthesis method that provides better reaction efficiency and spatial controllability has become a critical challenge. Herein, a photochemical synthesis of C9H4BO2 (COF-5) is demonstrated for the first time, by which “sea urchin-shaped” COF-5 (UV-COF-5) with uniform size is synthesized with a highly enhanced growth rate, ≈48 times faster than that of the solvothermal method for 75% yield. In addition, an enlarged surface area is measured from UV-COF-5, which originates from its hierarchical morphology. The selectively increased growth rate of UV-COF-5 in the [001] direction observed by microscopic analysis results in the local 1D morphology of the hierarchical structure. Density functional theory calculations determine that the enhanced growth rate along the [001] direction can be understood by the characteristic of the interlayer orbital coupling at the frontier energy region. In addition, this study successfully demonstrates the preparation of COF-5 patterns without any complicated postsynthesis lithography process, but simply by utilizing optical masks during the photochemical method.The synthesis of covalent organic framework-5 (COF-5) using a fast photochemical method that allows patterning, is reported for the first time. This novel method yields COF-5 of hierarchical, homogeneous sea-urchin-shaped morphology which has a fast growth rate along out-of-plane direction. Also, direct patterned growth of COF-5 is achieved using reusable optical masks, thereby exploiting using the technical benefit of photochemical synthesis over complicated lithographic processes.
  PubDate: 2017-07-04T00:41:49.276083-05:
  DOI: 10.1002/adfm.201700925
Nanoporous Nitrogen-Doped Graphene Oxide/Nickel Sulfide Composite Sheets
Derived from a Metal-Organic Framework as an Efficient Electrocatalyst for
Hydrogen and Oxygen Evolution
- Authors: Kolleboyina Jayaramulu; Justus Masa, Ondrej Tomanec, Daniel Peeters, Vaclav Ranc, Andreas Schneemann, Radek Zboril, Wolfgang Schuhmann, Roland A. Fischer
  Abstract: Engineering of controlled hybrid nanocomposites creates one of the most exciting applications in the fields of energy materials and environmental science. The rational design and in situ synthesis of hierarchical porous nanocomposite sheets of nitrogen-doped graphene oxide (NGO) and nickel sulfide (Ni7S6) derived from a hybrid of a well-known nickel-based metal-organic framework (NiMOF-74) using thiourea as a sulfur source are reported here. The nanoporous NGO/MOF composite is prepared through a solvothermal process in which Ni(II) metal centers of the MOF structure are chelated with nitrogen and oxygen functional groups of NGO. NGO/Ni7S6 exhibits bifunctional activity, capable of catalyzing both the hydrogen evolution reaction (HER) and the oxygen evolution reaction (OER) with excellent stability in alkaline electrolytes, due to its high surface area, high pore volume, and tailored reaction interface enabling the availability of active nickel sites, mass transport, and gas release. Depending on the nitrogen doping level, the properties of graphene oxide can be tuned toward, e.g., enhanced stability of the composite compared to commonly used RuO2 under OER conditions. Hence, this work opens the door for the development of effective OER/HER electrocatalysts based on hierarchical porous graphene oxide composites with metal chalcogenides, which may replace expensive commercial catalysts such as RuO2 and IrO2.A rational and simple methodology to fabricate hierarchical porous nanocomposite sheets of nitrogen-doped graphene oxide and nickel sulfide derived from a metal-organic framework is presented. The resulting composite shows bifunctional activity of hydrogen evolution reaction and oxygen evolution reaction with excellent stability in alkaline electrolytes.
  PubDate: 2017-07-03T07:22:43.146502-05:
  DOI: 10.1002/adfm.201700451
Gold Nanoparticles and g-C3N4-Intercalated Graphene Oxide Membrane for
Recyclable Surface Enhanced Raman Scattering
- Authors: Lulu Qu; Na Wang, Hui Xu, Weipeng Wang, Yang Liu, Lidia Kuo, T. P. Yadav, Jingjie Wu, Jarin Joyner, Yanhua Song, Haitao Li, Jun Lou, Robert Vajtai, Pulickel M. Ajayan
  Abstract: Toxic organic pollutants in the aquatic environment cause severe threats to both humans and the global environment. Thus, the development of robust strategies for detection and removal of these organic pollutants is essential. For this purpose, a multifunctional and recyclable membrane by intercalating gold nanoparticles and graphitic carbon nitride into graphene oxide (GNPs/g-C3N4/GO) is fabricated. The membranes exhibit not only superior surface enhanced Raman scattering (SERS) activity attributed to high preconcentration ability to analytes through π–π and electrostatic interactions, but also excellent catalytic activity due to the enhanced electron–hole separation efficiency. These outstanding properties allow the membrane to be used for highly sensitive detection of rhodamine 6G with a limit of detection of 5.0 × 10−14m and self-cleaning by photocatalytic degradation of the adsorbed analytes into inorganic small molecules, thus achieving recyclable SERS application. Furthermore, the excellent SERS activity of the membrane is demonstrated by detection of 4-chlorophenol at less than nanomolar level and no significant SERS or catalytic activity loss was observed when reusability is tested. These results suggest that the GNPs/g-C3N4/GO membrane provides a new strategy for eliminating traditional, single-use SERS substrates, and expands practical SERS application to simultaneous detection and removal of environmental pollutants.A multifunctional membrane including superior surface enhanced Raman scattering (SERS) and photocatalytic activity by intercalating gold nanoparticles and graphic carbon nitride into graphene oxide nanosheets is developed. The membrane exhibits the extraordinary ability for use in removal, SERS detection, and degradation of organic pollutants, holding great promise for environmental pollutants removal and monitoring.
  PubDate: 2017-07-03T07:22:12.021598-05:
  DOI: 10.1002/adfm.201701714
Synergistic Effect of Si Doping and Heat Treatments Enhances the
Photoelectrochemical Water Oxidation Performance of TiO2 Nanorod Arrays
- Authors: Changlong Chen; Yuling Wei, Guangzheng Yuan, Qinglong Liu, Ranran Lu, Xing Huang, Yi Cao, Peihua Zhu
  Abstract: TiO2 is a very promising photocatalytic material due to its merits including low cost, nontoxicity, high chemical stability, and photocorrosion resistance. However, it is also known that TiO2 is a wide bandgap material, and it is still challenging to achieve high photocatalytic performance driven by solar light. In this paper, silicon-doped TiO2 nanorod arrays are vertically grown on fluorine-doped tin oxide substrates and then are heat treated both in air and in vacuum. It is found that the silicon doping together with the heat treatment brings synergic effect to TiO2 nanorod films by increasing the crystallinity, producing abundant oxygen vacancies, enhancing the hydrophilicity as well as improving the electronic properties. When used as photoanodes in photoelectrochemical water splitting, under the condition of AM 1.5G simulated solar irradiation and without using any cocatalysts, these nanorod films show photocurrent density as high as 0.83 mA cm−2 at a potential of 1.23 V versus reversible hydrogen electrode, which is much higher than that of the TiO2 nanorod films without doping or heat treating. The silicon-doped TiO2 nanorod array films described in this paper are envisioned to provide valuable platforms for supporting catalysts and cocatalysts for efficient solar-light-assisted water oxidation and other solar-light-driven photocatalytic applications.TiO2 nanorod arrays subjected to Si doping and heat treatments achieve much-improved electronic properties due to the improvement of the crystallinity and the increase of the donor density, which are envisioned to provide valuable platforms for supporting catalysts and cocatalysts for efficient solar-light-assisted water oxidation and other solar-light-driven photocatalytic applications.
  PubDate: 2017-07-03T07:16:10.47211-05:0
  DOI: 10.1002/adfm.201701575
Robust Red Organic Nanoparticles for In Vivo Fluorescence Imaging of
Cancer Cell Progression in Xenografted Zebrafish
- Authors: Gengwei Lin; Purnima Naresh Manghnani, Duo Mao, Cathleen Teh, Yinghao Li, Zujin Zhao, Bin Liu, Ben Zhong Tang
  Abstract: Bright and red-emissive organic nanoparticles (NPs) are demonstrated as promising for in vivo fluorescence imaging. However, most red organic dyes show greatly weakened or quenched emission in the aggregated state. In this work, a robust red fluorophore (t-BPITBT-TPE) with strong aggregate-state photoluminescence and good biocompatibility is presented. The NPs comprised of t-BPITBT-TPE aggregates encapsulated within 1,2-distearoyl-sn-glycero-3-phosphoethanolamine-N-[methoxy(polyethylene glycol) (DSPE-mPEG) micelles exhibit a photoluminescence peak at 660 nm with a high fluorescence quantum yield of 32% in aqueous media. The NPs can be facilely charged by using the same polymeric matrix with different terminal groups, e.g., methoxy (DSPE-mPEG), amine (DSPE-PEG-NH2), or carboxymethyl (DSPE-PEG-COOH) groups. The biocompatibility, toxicity, circulation, and biodistribution of the NPs are assessed using the zebrafish model through whole embryo soaking and intravenous delivery. Furthermore, HeLa and MCF-7 cells tagged with t-BPITBT-TPE in DSPE-PEG-NH2-TAT polymer NPs are xenografted into zebrafish larvae to successfully track the cancer cell proliferation and metastasis, demonstrating that these new NPs are efficient cancer cell trackers. In addition, the NPs also show good in vivo imaging ability toward 4T1 tumors in xenografted BALB/c mice.Bright red organic nanoparticles are prepared for the study of their toxicity, circulation, and biodistribution in zebrafish. Different cancer cells tagged with these nanoparticles are xenografted into zebrafish larvae, realizing long-term tracing of their proliferation and metastasis in zebrafish.
  PubDate: 2017-07-03T01:41:38.594081-05:
  DOI: 10.1002/adfm.201701418
Large-Area, Flexible Broadband Photodetector Based on ZnS–MoS2
Hybrid on Paper Substrate
- Authors: P. Thanga Gomathi; Parikshit Sahatiya, Sushmee Badhulika
  Abstract: Flexible broadband photodetectors based on 2D MoS2 have gained significant attention due to their superior light absorption and increased light sensitivity. However, pristine MoS2 has absorption only in visible and near IR spectrum. This paper reports a paper-based broadband photodetector having ZnS–MoS2 hybrids as active sensing material fabricated using a simple, cost effective two-step hydrothermal method wherein trilayer MoS2 is grown on cellulose paper followed by the growth of ZnS on MoS2. Optimization in terms of process parameters is done to yield uniform trilayer MoS2 on cellulose paper. UV sensing property of ZnS and broadband absorption of MoS2 in visible and IR, broadens the range from UV to near IR. ZnS plays the dual role for absorption in UV and in the generation of local electric fields, thereby increasing the sensitivity of the sensor. The fabricated photodetector exhibits a higher responsivity toward the visible light when compared to UV and IR light. Detailed studies in terms of energy band diagram are presented to understand the charge transport mechanism. This represents the first demonstration of a paper-based flexible broadband photodetector with excellent photoresponsivity and high bending capability that can be used for wearable electronics, flexible security, and surveillance systems, etc.Herein, a paper-based broadband photodetector applying ZnS–MoS2 (trilayer) hybrids as active sensing material is reported for the first time. A simple hydrothermal process is used for fabrication. UV sensing property of ZnS and broadband absorption of MoS2 in visible and IR, broadens the range from UV to near- IR with higher sensitivity toward visible light.
  PubDate: 2017-07-03T01:40:47.791432-05:
  DOI: 10.1002/adfm.201701611
CuCo Bimetallic Oxide Quantum Dot Decorated Nitrogen-Doped Carbon
Nanotubes: A High-Efficiency Bifunctional Oxygen Electrode for Zn–Air
Batteries
- Authors: Hui Cheng; Mei-Ling Li, Chang-Yuan Su, Nan Li, Zhao-Qing Liu
  Abstract: The large-scale production of metal–air batteries, an appealing solution for next-generation energy storage, requires low-cost, earth-abundant, and efficient oxygen electrode materials, yet insights into active catalyst structures and synergistic reactivity remain largely unknown. Here, a new bifunctional oxygen electrode based on nitrogen-doped carbon nanotubes decorated by spinel CuCo2O4 quantum dots (CuCo2O4/N-CNTs) is reported, outperforming the benchmark of state-of-the-art noble metal catalysts. Combining spectroscopic characterization and electrochemical studies, a prominent synergetic effect between CuCo2O4 and N-doped carbon nanotubes is uncovered: the high conductivity, large active surface area, and increase in the number of catalytic sites induced by Cu doping (i.e., Cu2+ and CuN) can be beneficial to the overall electrocatalytic activities. Remarkably, the native flexibility of CuCo2O4/N-CNTs allows its direct use as reversible oxygen electrodes in Zn–air batteries either with liquid alkaline electrolyte or in the all-solid-state configuration. The prepared devices demonstrate excellent discharging/charging performance, large energy density (83.83 mW cm−2 in liquid state, 1.86 W g−1 in all-solid-state), and long lifetime (48 h in liquid state, 9 h in all-solid-state), holding great promise in the practical application of rechargeable metal–air batteries and other fuel cells.Advanced Cu Co bimetallic oxide are decorated on nitrogen-doped carbon nanotubes to serve as the bifunctional oxygen catalyst. A strong synergetic coupling in CuCo2O4/N-CNTs is proposed, which provides advantaged local chemical environment and enriched catalytic sites. Benefiting from these features, CuCo2O4/N-CNTs with reversible oxygen catalytic activity is capable of operating the new-generation rechargeable zinc–air batteries.
  PubDate: 2017-07-03T01:36:30.647522-05:
  DOI: 10.1002/adfm.201701833
PEDOT:PSS-Assisted Exfoliation and Functionalization of 2D Nanosheets for
High-Performance Organic Solar Cells
- Authors: Wang Xing; Yusheng Chen, Xiaoxi Wu, Xiaozhou Xu, Pan Ye, Ting Zhu, Qingyu Guo, Liqiu Yang, Weiwei Li, Hui Huang
  Abstract: Here, a facial and scalable method for efficient exfoliation of bulk transition metal dichalcogenides (TMD) and graphite in aqueous solution with poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) to prepare single- and few-layer nanosheets is demonstrated. Importantly, these TMD nanosheets retain the single crystalline characteristic, which is essential for application in organic solar cells (OSCs). The hybrid PEDOT:PSS/WS2 ink prepared by a simple centrifugation is directly integrated as a hole extraction layer for high-performance OSCs. Compared with PEDOT:PSS, the PEDOT:PSS/WS2-based devices provide a remarkable power conversion efficiency due to the “island” morphology and benzoid–quinoid transition. This study not only demonstrates a novel method for preparing single- and few-layer TMD and graphene nanosheets but also paves a way for their applications without further complicated processing.A novel PEDOT:PSS/2D nanosheets ink as hole extraction layer is used to fabricate high-performance organic solar cells. 2D nanosheets with single- and few-layer structure exist stably in the ink because of PEDOT:PSS exfoliation and functionalization. The enhanced power conversion efficiency arises from the “island” morphology and benzoid–quinoid transition upon addition of 2D nanosheets.
  PubDate: 2017-07-03T01:35:42.316022-05:
  DOI: 10.1002/adfm.201701622
Reversible Thermal Tuning of All-Dielectric Metasurfaces
- Authors: Mohsen Rahmani; Lei Xu, Andrey E. Miroshnichenko, Andrei Komar, Rocio Camacho-Morales, Haitao Chen, Yair Zárate, Sergey Kruk, Guoquan Zhang, Dragomir N. Neshev, Yuri S. Kivshar
  Abstract: All-dielectric metasurfaces provide a powerful platform for a new generation of flat optical devices, in particular, for applications in telecommunication systems, due to their low losses and high transparency in the infrared. However, active and reversible tuning of such metasurfaces remains a challenge. This study experimentally demonstrates and theoretically justifies a novel scenario of the dynamical reversible tuning of all-dielectric metasurfaces based on the temperature-dependent change of the refractive index of silicon. How to design an all-dielectric metasurface with sharp resonances by achieving interference between magnetic dipole and electric quadrupole modes of constituted nanoparticles arranged in a 2D lattice is shown. Thermal tuning of these resonances can cause drastic but reciprocal changes in the directional scattering of the metasurface in a spectral window of 75 nm. This change can result in a 50-fold enhancement of the radiation directionality. This type of reversible tuning can play a significant role in novel flat optical devices including the metalenses and metaholograms.Via controlling the temperature and employing the right combination of the electric and magnetic resonant responses of the metasurfaces, drastic and reciprocal interchanges in directional scattering are demonstrated experimentally and theoretically. At 1425 nm forward to backward ratio variation from 1 to>50 can be obtained. The results provide an important step toward tunable nanophotonic components and all-optical circuitry on a chip.
  PubDate: 2017-07-03T01:21:23.154565-05:
  DOI: 10.1002/adfm.201700580
Bioinspired Geometry-Switchable Janus Nanofibers for Eye-Readable H2
Sensors
- Authors: Heetak Han; Sangyul Baik, Borui Xu, Jungmok Seo, Sanggeun Lee, Sera Shin, Jaehong Lee, Ja Hoon Koo, Yongfeng Mei, Changhyun Pang, Taeyoon Lee
  Abstract: Nanoscale architectures found in nature have unique functionalities and their discovery has led to significant advancements in various fields including optics, wetting, and adhesion. The sensilla of arthropods, comprised of unique hierarchical structures, are a representative example which inspired the development of various bioinspired systems, owing to their hypersensitive and ultrafast responsivity to mechanical and chemical stimuli. This report presents a geometry-switchable and highly H2-reactive Janus nanofiber (H-NF) array inspired by the structural features of the arthropod sensilla. The H-NF array (400 nm diameter, 4 µm height, 1.2 µm spacing distance, and hexagonal array) exhibits reversible structural deformation when exposed to a flammable concentration of hydrogen gas (4 vol% H2 in N2) with fast response times (5.1 s). The structural change can be detected with the bare eye, which is a result of change in the optical transmittance due to the structural deformation of the H-NF array. Based on these results, an eye-readable H2-sensor that requires no additional electrical apparatus is demonstrated, including wetting-controllable H2-selective smart surfaces and H2-responsive fasteners.A highly H2-reactive Janus nanofiber (H-NF) array is developed, inspired by the structural features of arthropod sensilla. The H-NF array exhibits unique geometry-switchable behaviors in response to the presence/absence of hydrogen molecules. Based on the structural deformation of H-NF, various applications are demonstrated, including eye-readable H2-sensor, wetting-controllable H2-selective smart surfaces, and real-time monitoring via H2-detectable fasteners.
  PubDate: 2017-06-30T07:13:42.42348-05:0
  DOI: 10.1002/adfm.201701618
Electrostatic Tuning of Spray-Deposited ZnO for Controlled Mobility
Enhancement
- Authors: Andre Zeumault; William Scheideler, Vivek Subramanian
  Abstract: Spray-deposited nanocrystalline ZnO films are produced in order to establish empirical relationships between synthetic conditions and the density of states as a means of achieving electrostatic control. By varying the spray-pyrolysis deposition conditions, i.e., substrate temperature, precursor concentration, and flow rate, a wide range of exponentially distributed density of localized states profiles and field-effect mobility values ranging over three orders of magnitude (0.02–30 cm2 V−1 s−1) are obtained for analysis. It is found that mobility can be controlled by appropriately tuning the shape of the density of states profile, increasing the band tail slope and reducing the band edge concentration of shallow states. Most significantly, it is shown that the shape of the density of states can be modified by adjusting the spray-pyrolysis deposition conditions for electrostatic control. It is found that higher Zn precursor concentration in solution increases the slope of the band tails, leading to higher mobility. Additionally, the band edge concentration is reduced with increased substrate temperature also leading to higher mobility. These results quantify the relationship between defect electrostatics and electron transport while demonstrating electrostatic control via synthetic modification of localized states.Spray-deposited ZnO films are produced with a variety of density of states profiles. Controlled mobility enhancement is demonstrated by synthetically modifying the shape of the density of states: increasing the band tail slope by increasing Zn precursor concentration and reducing the band edge concentration of shallow states by increasing substrate temperature, thus enabling precision design of exceptional conductive oxide electronics.
  PubDate: 2017-06-30T07:13:10.996005-05:
  DOI: 10.1002/adfm.201701021
Flexible MXene/Graphene Films for Ultrafast Supercapacitors with
Outstanding Volumetric Capacitance
- Authors: Jun Yan; Chang E. Ren, Kathleen Maleski, Christine B. Hatter, Babak Anasori, Patrick Urbankowski, Asya Sarycheva, Yury Gogotsi
  Abstract: A strategy to prepare flexible and conductive MXene/graphene (reduced graphene oxide, rGO) supercapacitor electrodes by using electrostatic self-assembly between positively charged rGO modified with poly(diallyldimethylammonium chloride) and negatively charged titanium carbide MXene nanosheets is presented. After electrostatic assembly, rGO nanosheets are inserted in-between MXene layers. As a result, the self-restacking of MXene nanosheets is effectively prevented, leading to a considerably increased interlayer spacing. Accelerated diffusion of electrolyte ions enables more electroactive sites to become accessible. The freestanding MXene/rGO-5 wt% electrode displays a volumetric capacitance of 1040 F cm−3 at a scan rate of 2 mV s−1 , an impressive rate capability with 61% capacitance retention at 1 V s−1 and long cycle life. Moreover, the fabricated binder-free symmetric supercapacitor shows an ultrahigh volumetric energy density of 32.6 Wh L−1, which is among the highest values reported for carbon and MXene based materials in aqueous electrolytes. This work provides fundamental insight into the effect of interlayer spacing on the electrochemical performance of 2D hybrid materials and sheds light on the design of next-generation flexible, portable and highly integrated supercapacitors with high volumetric and rate performances.MXene/reduced graphene oxide (rGO) hybrid films are prepared through electrostatic self-assembly of negatively charged MXene nanosheets and positively charged rGO nanosheets. rGO nanosheets are inserted in between MXene layers as conductive spacers, efficiently alleviating the self-restacking of both rGO and MXene. As a result, the hybrid films exhibit ultrahigh volumetric capacitance and an impressive rate capability.
  PubDate: 2017-06-30T07:12:38.563233-05:
  DOI: 10.1002/adfm.201701264
Distinct Bimodal Roles of Aromatic Molecules in Controlling Gold Nanorod
Growth for Biosensing
- Authors: Jun Hui Soh; Yiyang Lin, Michael R. Thomas, Nevena Todorova, Charalambos Kallepitis, Irene Yarovsky, Jackie Y. Ying, Molly M. Stevens
  Abstract: New aromatic molecule–seed particle interactions are examined and exploited to control and guide seed-mediated gold nanorod (Au NR) growth. This new approach enables better understanding of how small molecules impact the synthesis of metallic nanostructures, catalyzing their use in various biomedical applications, such as plasmonic biosensing. Experimental studies and theoretical molecular simulations using a library of aromatic molecules, making use of the chemical versatility of the molecules with varied spatial arrangements of electron-donating/withdrawing groups, charge, and Au-binding propensity, are performed. Au NR growth is regulated by two principal mechanisms, producing either a red or blue shift in the longitudinal localized surface plasmon resonance (LLSPR) peaks. Aromatic molecules with high redox potentials produce an increase in NR aspect ratio and red shift of LLSPR peaks. In contrast, molecules that strongly bind gold surfaces result in blue shifts, demonstrating a strong correlation between their binding energy and blue shifts produced. Through enzymatic conversion of selected molecules, 4-aminophenylphosphate to 4-aminophenol, opposing growth mechanisms at opposite extremes of target concentration are obtained, and a chemical pathway for performing plasmonic enzyme-linked immunosorbent assays is established. This unlocks new strategies for tailoring substrate design and enzymatic mechanisms for controlling plasmonic response to target molecules in biosensing applications.Aromatic molecule–seed particle interactions are introduced as a novel chemical approach to control anisotropic growth of gold nanorods (Au NRs). The interaction of seeds with reducing aromatic molecules produces Au NRs with higher aspect ratios and red-shifted plasmonic peaks, while the interaction with gold surface-binding molecules yields Au NRs with lower aspect ratios and blue-shifted peaks. These observations enable more sophisticated engineering of anisotropic nanoparticle growth.
  PubDate: 2017-06-26T09:19:03.679167-05:
  DOI: 10.1002/adfm.201700523
Highly Stable Colloidal “Giant” Quantum Dots Sensitized Solar
Cells
- Authors: Gurpreet S. Selopal; Haiguang Zhao, Xin Tong, Daniele Benetti, Fabiola Navarro-Pardo, Yufeng Zhou, David Barba, François Vidal, Zhiming M. Wang, Federico Rosei
  Abstract: Colloidal quantum dots (QDs) are widely studied due to their promising optoelectronic properties. This study explores the application of specially designed and synthesized “giant” core/shell CdSe/(CdS)x QDs with variable CdS shell thickness, while keeping the core size at 1.65 nm, as a highly efficient and stable light harvester for QD sensitized solar cells (QDSCs). The comparative study demonstrates that the photovoltaic performance of QDSCs can be significantly enhanced by optimizing the CdS shell thickness. The highest photoconversion efficiency (PCE) of 3.01% is obtained at optimum CdS shell thickness ≈1.96 nm. To further improve the PCE and fully highlight the effect of core/shell QDs interface engineering, a CdSexS1−x interfacial alloyed layer is introduced between CdSe core and CdS shell. The resulting alloyed CdSe/(CdSexS1−x)5/(CdS)1 core/shell QD-based QDSCs yield a maximum PCE of 6.86%, thanks to favorable stepwise electronic band alignment and improved electron transfer rate with the incorporation of CdSexS1−x interfacial layer with respect to CdSe/(CdS)6 core/shell. In addition, QDSCs based on “giant” core/CdS-shell or alloyed core/shell QDs exhibit excellent long-term stability with respect to bare CdSe-based QDSCs. The giant core/shell QDs interface engineering methodology offers a new path to improve PCE and the long-term stability of liquid junction QDSCs.The “giant” alloyed CdSe/(CdSexS1−x)5/(CdS)1 core/shell quantum dots (QDs) show superior optoelectronic properties, such as broader absorption spectrum, and better carrier separation and transfer rate with respect to CdSe/(CdS)6 core/shell QDs. The alloyed core/shell QDs sensitized solar cells (QDSCs) exhibit a photoconversion efficiency of 6.86% and excellent long-term stability, and offer a new path for liquid junction QDSCs technology.
  PubDate: 2017-06-26T09:13:07.369372-05:
  DOI: 10.1002/adfm.201701468
Fully-Inkjet-Printed Ag-Coil/NiZn-Ferrite for Flexible Wireless Power
Transfer Module: Rigid Sintered Ceramic Body into Flexible Form
- Authors: Murali Bissannagari; Woosung Lee, Woong Yong Lee, Jun Hwan Jeong, Jihoon Kim
  Abstract: Despite the material performances being superior to those of organic materials, inorganic materials are typically excluded for use in flexible and deformable electronic systems because of their rigid nature and the requirement for high processing temperature. This work presents a novel method of utilizing rigid NiZn-ferrite films in a flexible platform and offers an opportunity to realize a flexible wireless power transfer (WPT) module. Inkjet printing is introduced in this study since it can coat NiZn-ferrite films as well as pattern inductor coils for WPTs. A thermochemically inert buffer layer is selected based on a thermodynamic analysis and is introduced as a buffer layer for the NiZn-ferrite to prevent chemical reaction between the ferrite film and the substrate and ensure that the ferrite film can be easily separated from the substrate during a high-temperature sintering process. A Ag-inductor coil is printed on the NiZn-ferrite layer, and then the entire layer is embedded into polydimethylsiloxane, which renders the WPT module flexible. The flexibility of the WPT module is characterized by a bending test, and the structural and magnetic properties are also investigated. The performance of the flexible WPT module is demonstrated by transmitting wireless power to a light emitting diode.A flexible wireless power transfer (WPT) module is prepared by embedding a Ag-inductor coil/NiZn-ferrite layer into polydimethylsiloxane. This work presents a creative method to utilize a rigid ferrite film in a flexible platform for future flexible electronics. The performance of the flexible WPT module is demonstrated by transmitting a wireless power to a light emitting diode.
  PubDate: 2017-06-26T01:13:25.685267-05:
  DOI: 10.1002/adfm.201701766
Highly Robust Bendable Oxide Thin-Film Ts on Polyimide Substrates via Mesh
and Strip Patterning of Device Layers
- Authors: Suhui Lee; Daun Jeong, Mallory Mativenga, Jin Jang
  Abstract: Advancement in thin-film transistor (TFT) technologies has extended to applications that can withstand extreme bending or folding. The changes of the performances of amorphous-indium-gallium-zinc-oxide (a-IGZO) TFTs on polyimide substrate after application of extreme mechanical bending strain are studied. The TFT designs include mesh and strip patterned source/drain metal lines as well as strip patterned a-IGZO semiconductor layer. The robustness of the a-IGZO TFTs with the strain of 2.17% corresponding to the radius of 0.32 mm is tested and no crack generation even after 60 000 bending cycles is found. The split of source/drain electrodes and semiconductor layer can improve the mechanical bending stability of the TFTs. This can be possible by using conventional TFT manufacturing process so that this technology can be easily applied to build robust TFT array for foldable displays.Extremely stable high-performance a-IGZO thin-film transistors (TFT) on plastic substrates are achieved by splitting S/D/G electrodes and the active semiconductor layer. When the S/D/G electrodes are patterned as metal mesh with strip-patterned a-IGZO layer, mechanical stability of the TFT can be greatly improved and thus there is no crack generation even after 60 000 bending cycles with the radius of 0.32 mm.
  PubDate: 2017-06-23T02:03:10.2642-05:00
  DOI: 10.1002/adfm.201700437
Deciphering the NH4PbI3 Intermediate Phase for Simultaneous Improvement on
Nucleation and Crystal Growth of Perovskite
- Authors: Haonan Si; Qingliang Liao, Zhuo Kang, Yang Ou, JingJing Meng, Yichong Liu, Zheng Zhang, Yue Zhang
  Abstract: The NH4PbI3-based phase transformation is realized by simply adding NH4I additive, in order to simultaneously control perovskite nucleation and crystal growth. Regarding the nucleation process, the NH4+ with small ionic radius preferentially diffuses into the [PbI6]4− octahedral layer to form NH4PbI3, which compensates the lack of CH3NH3I (MAI) precipitation. The generation of NH4PbI3 intermediate phase results in extra heterogeneous nucleation sites and reduces the defects derived from the absence of MA+. Regarding the crystal growth process, the cation exchange process between MA+ and NH4+, instead of the MAs directly entering, successfully retards the crystal growth. Such NH4PbI3 consumption process slows down the crystal growth, which effectively improves the perovskite quality with lowered defect density. The cooperation of these two effects eventually leads to the high-quality perovskite with enlarged grain size, prolonged photoluminescence lifetime, lowered defect density, and increased carrier concentration, as well as the finally enhanced photovoltaic performance. Moreover, NH3 as a byproduct further facilitates the proposed transformation process and no external residue remains even without any post-treatment. Such methodology of introducing a novel phase transformation to simultaneously control nucleation and crystal growth processes is of universal significance for further devotion in the foreseeable perovskite solar cells (PSCs) evolution.An innovative NH4I-induced phase transformation is designed to optimize the perovskite crystallization from both nucleation and crystal growth aspects. The rational designed intermediate phase NH4PbI3 simultaneously contributes to the extra heterogeneous nucleation sites and slows down crystal growth rate, which finally leads to the optimized perovskite quality and advanced photovoltaic performance with extra 10% improvement.
  PubDate: 2017-06-22T01:51:46.609042-05:
  DOI: 10.1002/adfm.201701804
Morphological Evolution and Magnetic Property of Rare-Earth-Doped Hematite
Nanoparticles: Promising Contrast Agents for T1-Weighted Magnetic
Resonance Imaging
- Authors: Hao Wan; Pengfei Rong, Xiaohe Liu, Litong Yang, Yong Jiang, Ning Zhang, Renzhi Ma, Shuquan Liang, Haidong Wang, Guanzhou Qiu
  Abstract: A series of uniform rare-earth-doped hematite (α-Fe2O3) nanoparticles are synthesized by a facile hydrothermal strategy. In a typical case of gadolinium (Gd)-doped α-Fe2O3, the morphology and chemical composition can be readily tailored by tuning the initial proportion of Gd3+/Fe3+ sources. As a result, the products are observed to be stretched into more elongated shapes with an increasing dopant ratio. As a benefit of such an elongated morphological feature and Gd3+ ions of larger effective magnetic moment than Fe3+, the doped product with the highest ratio of Gd3+ at 5.7% shows abnormal ferromagnetic features with a remnant magnetization of 0.605 emu g−1 and a coercivity value of 430 Oe at 4 K. Density of states calculations also reveal the increase of total magnetic moment induced by Gd3+ dopant in α-Fe2O3 hosts, as well as possible change of magnetic arrangement. As-synthesized Gd-doped α-Fe2O3 nanoparticles are probed as contrast agents for T1-weighted magnetic resonance imaging, achieving a remarkable enhancement effect for both in vitro and in vivo tests.The morphology and chemical composition of rare-earth-doped hematite nanoparticles can be readily tailored, bringing about a ferromagnetic feature with the highest Gd3+ dopant ratio of 5.7%. As-synthesized Gd-doped hematite nanoparticles are revealed as promising contrast agents for T1-weighted magnetic resonance imaging, achieving a remarkable enhancement effect for both in vitro and in vivo tests.
  PubDate: 2017-06-07T01:55:34.243822-05:
  DOI: 10.1002/adfm.201606821
Elastomeric Fibrous Hybrid Scaffold Supports In Vitro and In Vivo Tissue
Formation
- Authors: Nafiseh Masoumi; Dane Copper, Peter Chen, Alexander Cubberley, Kai Guo, Ruei-Zeng Lin, Bayoumi Ahmed, David Martin, Elena Aikawa, Juan Melero-Martin, John Mayer
  Abstract: Biomimetic materials with biomechanical properties resembling those of native tissues while providing an environment for cell growth and tissue formation, are vital for tissue engineering (TE). Mechanical anisotropy is an important property of native cardiovascular tissues and directly influences tissue function. This study reports fabrication of anisotropic cell-seeded constructs while retaining control over the construct's architecture and distribution of cells. Newly synthesized poly-4-hydroxybutyrate (P4HB) is fabricated with a dry spinning technique to create anelastomeric fibrous scaffold that allows control of fiber diameter, porosity, and rate ofdegradation. To allow cell and tissue ingrowth, hybrid scaffolds with mesenchymalstem cells (MSCs) encapsulated in a photocrosslinkable hydrogel were developed. Culturing the cellularized scaffolds in a cyclic stretch/flexure bioreactor resulted in tissue formation and confirmed the scaffold's performance under mechanical stimulation. In vivo experiments showed that the hybrid scaffold is capable of withstanding physiological pressures when implanted as a patch in the pulmonary artery. Aligned tissue formation occurred on the scaffold luminal surface without macroscopic thrombus formation. This combination of a novel, anisotropic fibrous scaffold and a tunable native-like hydrogel for cellular encapsulation promoted formation of 3D tissue and provides a biologically functional composite scaffold for soft-tissue engineering applications.Hybrid scaffolds composed of synthetic and biologic materials offer the potential for optimizing both cell compatibility and biomechanical characteristics of scaffolds for cardiovascular tissue engineered structures. The effects of fiber alignment, hydrogel incorporation, cellularization, and in vitro mechanical signaling are evaluated on electrospun poly-4-hydroxybutyrate scaffolds.
  PubDate: 2017-06-05T13:16:42.122794-05:
  DOI: 10.1002/adfm.201606614
Tunable Gas Sensing Gels by Cooperative Assembly
- Authors: Abid Hussain; Ana T. S. Semeano, Susana I. C. J. Palma, Ana S. Pina, José Almeida, Bárbara F. Medrado, Ana C. C. S. Pádua, Ana L. Carvalho, Madalena Dionísio, Rosamaria W. C. Li, Hugo Gamboa, Rein V. Ulijn, Jonas Gruber, Ana C. A. Roque
  Abstract: The cooperative assembly of biopolymers and small molecules can yield functional materials with precisely tunable properties. Here, the fabrication, characterization, and use of multicomponent hybrid gels as selective gas sensors are reported. The gels are composed of liquid crystal droplets self-assembled in the presence of ionic liquids, which further coassemble with biopolymers to form stable matrices. Each individual component can be varied and acts cooperatively to tune gels' structure and function. The unique molecular environment in hybrid gels is explored for supramolecular recognition of volatile compounds. Gels with distinct compositions are used as optical and electrical gas sensors, yielding a combinatorial response conceptually mimicking olfactory biological systems, and tested to distinguish volatile organic compounds and to quantify ethanol in automotive fuel. The gel response is rapid, reversible, and reproducible. These robust, versatile, modular, pliant electro-optical soft materials possess new possibilities in sensing triggered by chemical and physical stimuli.Self-assembled hybrid gels result from the unconventional combination of functional components, liquid crystals for reporting, ionic liquid as solvent, biopolymer as matrix, giving rise to molecular recognition properties not seen in the individual components. Thin films prepared from the gels are robust and exhibit dual optical/electrical stimuli-responsive properties in the presence of gases.
  PubDate: 2017-05-29T04:44:40.348737-05:
  DOI: 10.1002/adfm.201700803
High Electroactive Material Loading on a Carbon Nanotube@3D Graphene
Aerogel for High-Performance Flexible All-Solid-State Asymmetric
Supercapacitors
- Authors: Zhenghui Pan; Meinan Liu, Jie Yang, Yongcai Qiu, Wanfei Li, Yan Xu, Xinyi Zhang, Yuegang Zhang
  Abstract: Freestanding carbon-based hybrids, specifically carbon nanotube@3D graphene (CNTs@3DG) hybrid, are of great interest in electrochemical energy storage. However, the large holes (about 400 µm) in the commonly used 3D graphene foams (3DGF) constitute as high as 90% of the electrode volume, resulting in a very low loading of electroactive materials that is electrically connected to the carbon, which makes it difficult for flexible supercapacitors to achieve high gravimetric and volumetric energy density. Here, a hierarchically porous carbon hybrid is fabricated by growing 1D CNTs on 3D graphene aerogel (CNTs@3DGA) using a facile one-step chemical vapor deposition process. In this architecture, the 3DGA with ample interconnected micrometer-sized pores (about 5 µm) dramatically enhances mass loading of electroactive materials comparing with 3DGF. An optimized all-solid-state asymmetric supercapacitor (AASC) based on MnO2@CNTs@3DGA and Ppy@CNTs@3DGA electrodes exhibits high volumetric energy density of 3.85 mW h cm−3 and superior long-term cycle stability with 84.6% retention after 20 000 cycles, which are among the best reported for AASCs with both electrodes made of pseudocapacitive electroactive materials.A simple, scalable, and environmentally friendly method is described for preparing a novel carbon nanotube (CNT)@3D graphene aerogel (3DGA) that acts as an ideal support for high loading of electroactive materials. Lightweight and flexible all-solid-state asymmetric supercapacitors are assembled from the MnO2@CNTs@3DGA and polypyrrole@CNTs@3DGA electrodes. The devices realize high areal capacitance and superior mechanical strength and hold great promise for future flexible electronics.
  PubDate: 2017-05-26T00:46:33.393282-05:
  DOI: 10.1002/adfm.201701122
Conductive Metal–Organic Framework Nanowire Array Electrodes for
High-Performance Solid-State Supercapacitors
- Authors: Wen-Hua Li; Kui Ding, Han-Rui Tian, Ming-Shui Yao, Bhaskar Nath, Wei-Hua Deng, Yaobing Wang, Gang Xu
  Abstract: The application of conventional metal–organic frameworks (MOFs) as electrode materials in supercapacitors is largely hindered by their conventionally poor electrical conductivity. This study reports the fabrication of conductive MOF nanowire arrays (NWAs) and the application of them as the sole electrode material for solid-state supercapacitors. By taking advantage of the nanostructure and making full use of the high porosity and excellent conductivity, the MOF NWAs in solid-state supercapacitor show the highest areal capacitance and best rate performance of all reported MOF materials for supercapacitors, which is even comparable to most carbon materials.Conductive metal–organic framework (MOF) nanowire arrays (NWAs) are prepared as the sole electrode material for solid-state supercapacitors. By taking advantage of their nanostructure and making full use of the high porosity and excellent conductivity, the MOF NWAs in the solid-state supercapacitor show the highest areal capacitance and best rate performance of all reported MOF materials.
  PubDate: 2017-05-26T00:46:26.992477-05:
  DOI: 10.1002/adfm.201702067
Supramolecular-Assembled Nanoporous Film with Switchable Metal Salts for a
Triboelectric Nanogenerator
- Authors: Chanho Park; Giyoung Song, Suk Man Cho, Jihoon Chung, Yujeong Lee, Eui Hyuk Kim, Minjoo Kim, Sangmin Lee, June Huh, Cheolmin Park
  Abstract: A triboelectric nanogenerators (TENG) are of great interest as emerging power harvesters because of their simple device architecture with unprecedented high efficiency. Despite the substantial development of new constituent materials and device architectures, a TENG with a switchable surface on a single device, which allows for facile control of the triboelectric output performance, remains a challenge. Here, a supramolecular route for fabricating a novel TENG based on an alkali-metal-bound porous film, where the alkali metal ions are readily switched among one another is demonstrated. The soft nanoporous TENG contains numerous SO3− groups on the surface of nanopores prepared from the supramolecular assembly of sulfonic-acid-terminated polystyrene and poly(2-vinylpyridine) (P2VP), followed by soft etching of P2VP. Selective binding of alkali metal ions, including Li+, Na+, K+, and Cs+, with SO3− groups enables the development of mechanically robust alkali-metal-ion-decorated TENGs. The triboelectric output performance of the devices strongly depends on the alkali metal ion species, and the output power ranges from 11.5 to 256.5 µW. This wide-range triboelectric tuning can be achieved simply by a conventional ion exchange process in a reversible manner, thereby allowing reversible control of the output performance in a single device platform.A supramolecular route for the fabrication of surface-tunable triboelectric nanogenerators is developed. The method is based on a nanoporous surface capable of binding with alkali metal ions, which are readily switchable among one another, via a conventional ion exchange process. This allows for the repeated and reversible switching of the triboelectric properties in a single device platform.
  PubDate: 2017-05-24T00:55:45.470924-05:
  DOI: 10.1002/adfm.201701367
Oxygen Vacancies Evoked Blue TiO2(B) Nanobelts with Efficiency Enhancement
in Sodium Storage Behaviors
- Authors: Yan Zhang; Zhiying Ding, Christopher W. Foster, Craig E. Banks, Xiaoqing Qiu, Xiaobo Ji
  Abstract: Oxygen vacancies (OVs) dominate the physical and chemical properties of metal oxides, which play crucial roles in the various fields of applications. Density functional theory calculations show the introduction of OVs in TiO2(B) gives rise to better electrical conductivity and lower energy barrier of sodiation. Here, OVs evoked blue TiO2(B) (termed as B-TiO2(B)) nanobelts are successfully designed upon the basis of electronically coupled conductive polymers to TiO2, which is confirmed by electron paramagnetic resonance and X-ray photoelectron spectroscopy. The superiorities of OVs with the aid of carbon encapsulation lead to higher capacity (210.5 mAh g−1 (B-TiO2(B)) vs 102.7 mAh g−1 (W-TiO2(B)) at 0.5 C) and remarkable long-term cyclability (the retention of 94.4% at a high rate of 10 C after 5000 times). In situ X-ray diffractometer analysis spectra also confirm that an enlarged interlayer spacing stimulated by OVs is beneficial to accommodate insertion and removal of sodium ions to accelerate storage kinetics and preserve its original crystal structure. The work highlights that injecting OVs into metal oxides along with carbon coating is an effective strategy for improving capacity and cyclability performances in other metal oxide based electrochemical energy systems.Oxygen vacancies (OVs) evoked blue-colored TiO2(B) nanobelts are first designed as superior anodes for sodium-ion batteries. They feature remarkable high-rate performance and durable long-term cycle life because of their ability to take full advantage of OVs to elevate electronic conductivity and lower sodiated energy barriers. A high capacity of 80.9 mAh g−1 (at 3350 mA g−1) is still maintained after 5000 cycles.
  PubDate: 2017-05-24T00:55:35.461368-05:
  DOI: 10.1002/adfm.201700856
General Formation of Monodisperse IrM (M = Ni, Co, Fe) Bimetallic
Nanoclusters as Bifunctional Electrocatalysts for Acidic Overall Water
Splitting
- Authors: Yecan Pi; Qi Shao, Pengtang Wang, Jun Guo, Xiaoqing Huang
  Abstract: The development of bifunctional electrocatalysts for overall water splitting in acidic media is vital for polymer electrolyte membrane (PEM) electrolyzers, but still full of obstacles. Here, highly efficient acidic overall water splitting is realized by utilizing ultrasmall, monodispersed Iridium (Ir)-based nanoclusters (NCs) as the candidate, via a surfactant-free, wet-chemical, and large-scalable strategy. Benefiting from the high specific surface area, clean surface, and strong binding between NCs and supports, the IrM NCs exhibit attractive activities and durability for both oxygen evolution reaction and hydrogen evolution reaction in acidic electrolytes, with IrNi NCs showing the best performance. More significantly, in the overall water splitting, IrNi NCs reach 10 mA cm−2 at a cell voltage of only 1.58 V in 0.5 m H2SO4 electrolyte, holding promises for potential implementation of PEM water electrolysis. This work opens a new avenue toward designing bifunctional “acidic stable” catalysts for efficient overall water splitting.Ir-based nanoclusters (NCs) with highly dispersive feature are synthesized using a wet-chemical large-scalable strategy. Benefiting from the clean surface, high surface-to-volume ratio, large proportion of surface atoms, as well as strong interaction with support, this new series of Ir-based NCs exhibit superior activity and enhanced durability as bifunctional electrocatalysts for overall water splitting in acidic electrolyte.
  PubDate: 2017-05-16T06:11:05.5903-05:00
  DOI: 10.1002/adfm.201700886
Deep-Blue Phosphorescent Ir(III) Complexes with Light-Harvesting
Functional Moieties for Efficient Blue and White PhOLEDs in
Solution-Process
- Authors: Ganguri Sarada; Woosum Cho, Athithan Maheshwaran, Vijaya Gopalan Sree, Ho-Yeol Park, Yeong-Soon Gal, Myungkwan Song, Sung-Ho Jin
  Abstract: The photoluminescence (PL) efficiency of emitters is a key parameter to accomplish high electroluminescent performance in phosphorescent organic light-emitting diodes (PhOLEDs). With the aim of enhancing the PL efficiency, this study designs deep-blue emitting heteroleptic Ir(III) complexes (tBuCN-FIrpic, tBuCN-FIrpic-OXD, and tBuCN-FIrpic-mCP) for solution-processed PhOLEDs by covalently attaching the light-harvesting functional moieties (mCP-Me or OXD-Me) to the control Ir(III) complex, tBuCN-FIrpic. These Ir(III) complexes show similar deep-blue emission peaks around 453, 480 nm (298 K) and 447, 477 nm (77 K) in chloroform. tBuCN-FIrpic-mCP demonstrates higher light-harvesting efficiency (142%) than tBuCN-FIrpic-OXD (112%), relative to that of tBuCN-FIrpic (100%), due to an efficient intramolecular energy transfer from the mCP group to the Ir(III) complex. Accordingly, the monochromatic PhOLEDs of tBuCN-FIrpic-mCP show higher external quantum efficiency (EQE) of 18.2% with one of the best blue coordinates (0.14, 0.18) in solution-processing technology. Additionally, the two-component (deep-blue:yellow-orange), single emitting layer, white PhOLED of tBuCN-FIrpic-mCP shows a maximum EQE of 20.6% and superior color quality (color rendering index (CRI) = 78, Commission Internationale de L'Eclairage (CIE) coordinates of (0.353, 0.352)) compared with the control device containing sky-blue:yellow-orange emitters (CRI = 60, CIE coordinates of (0.293, 0.395)) due to the good spectral coverage by the deep-blue emitter.Highly efficient deep-blue phosphorescent Ir(III) complexes with light-harvesting groups are introduced for blue and white phosphorescent organic light-emitting diodes. Intramolecular energy transfer from a high triplet energy donor (mCP-Me) to the Ir(III) complex (tBuCN-FIrpic) is found to increase the photoluminescence efficiency of tBuCN-FIrpic-mCP. Therefore, tBuCN-FIrpic-mCP shows high external quantum efficiency of 18.2% with intense blue coordinates (0.142, 0.181) in a solution-process.
  PubDate: 2017-05-16T02:05:55.899905-05:
  DOI: 10.1002/adfm.201701002
Mo2C/CNT: An Efficient Catalyst for Rechargeable Li–CO2 Batteries
- Authors: Yuyang Hou; Jiazhao Wang, Lili Liu, Yuqing Liu, Shulei Chou, Dongqi Shi, Huakun Liu, Yuping Wu, Weimin Zhang, Jun Chen
  Abstract: The rechargeable Li–CO2 battery is a novel and promising energy storage system with the capability of CO2 capture due to the reversible reaction between lithium ions and carbon dioxide. Carbon materials as the cathode, however, limit both the cycling performance and the energy efficiency of the rechargeable Li–CO2 battery, due to the insulating Li2CO3 formed in the discharge process, which is difficult to decompose in the charge process. Here, a Mo2C/carbon nanotube composite material is developed as the cathode for the rechargeable Li–CO2 battery and can achieve high energy efficiency (77%) and improved cycling performance (40 cycles). A related mechanism is proposed that Mo2C can stabilize the intermediate reduction product of CO2 on discharge, thus preventing the formation of insulating Li2CO3. In contrast to insulating Li2CO3, this amorphous Li2C2O4-Mo2C discharge product can be decomposed below 3.5 V on charge. The introduction of Mo2C provides an effective solution to the problem of low round-trip efficiency in the Li–CO2 battery.In a rechargeable Li–CO2 battery, molybdenum carbide/carbon nanotubes as a cathode can stabilize the intermediate product on discharge, by building a new chemical bond between Mo and O. This amorphous discharge product effectively prevents the formation of crystalline Li2CO3 and thereby reduces the potential plateau on charge and improves the round-trip efficiency of the rechargeable Li–CO2 battery.
  PubDate: 2017-05-16T02:05:51.654232-05:
  DOI: 10.1002/adfm.201700564
Photocatalytic Nanofiltration Membranes with Self-Cleaning Property for
Wastewater Treatment
- Authors: Yan Lv; Chao Zhang, Ai He, Shang-Jin Yang, Guang-Peng Wu, Seth B. Darling, Zhi-Kang Xu
  Abstract: Membrane fouling is one of the most severe problems restricting membrane separation technology for wastewater treatment. This work reports a photocatalytic nanofiltration membrane (NFM) with self-cleaning property fabricated using a facile biomimetic mineralization process. In this strategy, a polydopamine (PDA)/polyethyleneimine (PEI) intermediate layer is fabricated on an ultrafiltration membrane via a co-deposition method followed by mineralization of a photocatalytic layer consisting of β-FeOOH nanorods. The PDA–PEI layer acts both as a nanofiltration selective layer and an intermediate layer for anchoring the β-FeOOH nanorods via strong coordination complexes between Fe3+ and catechol groups. In visible light, the β-FeOOH layer exhibits efficient photocatalytic activity for degrading dyes through the photo-Fenton reaction in the presence of hydrogen peroxide, endowing the NFM concurrently with effective nanofiltration performance and self-cleaning capability. Moreover, the mineralized NFMs exhibit satisfactory stability under simultaneous filtration and photocatalysis processing, showing great potential in advanced wastewater treatment.A photocatalytic nanofiltration membrane (NFM) with self-cleaning capability is fabricated via a facile biomimetic mineralization process. In visible light, this membrane exhibits efficient photocatalytic activity for degrading dyes through the photo-Fenton reaction concurrently with effective nanofiltration performance. The as-prepared NFM shows great potential in advanced textile wastewater treatment with satisfactory stability.
  PubDate: 2017-05-16T02:05:43.274182-05:
  DOI: 10.1002/adfm.201700251
Few-Layered PtS2 Phototransistor on h-BN with High Gain
- Authors: Liang Li; Weike Wang, Yang Chai, Huiqiao Li, Mingliang Tian, Tianyou Zhai
  Abstract: The very recently rediscovered group-10 transition metal dichalcogenides (TMDs) such as PtS2 and PtSe2, have joined the 2D material family as potentially promising candidates for electronic and optoeletronic applications due to their theoretically high carrier mobility, widely tunable bandgap, and ultrastability. Here, the first exploration of optoelectronic application based on few-layered PtS2 using h-BN as substrate is presented. The phototransistor exhibits high responsivity up to 1.56 × 103 A W−1 and detectivity of 2.9 × 1011 Jones. Additionally, an ultrahigh photogain ≈2 × 106 is obtained at a gate voltage Vg = 30 V, one of the highest gain among 2D photodetectors, which is attributed to the existence of trap states. More interestingly, the few-layered PtS2 phototransistor shows a back gate modulated photocurrent generation mechanism, that is, from the photoconductive effect dominant to photogating effect dominant via tuning the gate voltage from the OFF state to the ON state. Such good properties combined with gate-controlled photoresponse of PtS2 make it a competitive candidate for future 2D optoelectronic applications.A few-layered PtS2 phototransistor on h-BN with high gain is demonstrated. High responsivity up to 1.56 × 103 A W−1 and detectivity of 2.9 × 1011 Jones at a gate voltage Vg = 0 V are achieved. Moreover, the photocurrent generation mechanism can be tuned with the back gate from photoconductive effect dominant in the OFF state to photogating effect dominant in the ON state.
  PubDate: 2017-05-15T11:46:40.235465-05:
  DOI: 10.1002/adfm.201701011
A Band-Edge Potential Gradient Heterostructure to Enhance Electron
Extraction Efficiency of the Electron Transport Layer in High-Performance
Perovskite Solar Cells
- Authors: Yu Hou; Xiao Chen, Shuang Yang, Chunzhong Li, Huijun Zhao, Hua Gui Yang
  Abstract: As the key component in efficient perovskite solar cells, the electron transport layer (ETL) can selectively collect photogenerated charge carriers produced in perovskite absorbers and prevent the recombination of carriers at interfaces, thus ensuring a high power conversion efficiency. Compared with the conventional single- or dual-layered ETLs, a gradient heterojunction (GHJ) strategy is more attractive to facilitate charge separation because the potential gradient created at an appropriately structured heterojunction can act as a driving force to regulate the electron transport toward a desired direction. Here, a SnO2/TiO2 GHJ interlayer configuration inside the ETL is reported to simultaneously achieve effective extraction and efficient transport of photoelectrons. With such an interlayer configuration, the GHJs formed at the perovskite/ETL interface act collectively to extract photogenerated electrons from the perovskite layer, while GHJs formed at the boundaries of the interconnected SnO2 and TiO2 networks throughout the entire ETL layer can extract electron from the slow electron mobility TiO2 network to the high electron mobility SnO2 network. Devices based on GHJ ETL exhibit a champion power conversion efficiency of 18.08%, which is significantly higher than that obtained from the compact TiO2 ETL constructed under the comparable conditions.A gradient heterojunction electron transport layer (GHJ ETL), prepared by a facile low-temperature route, is utilized in perovskite solar cells (PSCs) for the first time. PSCs based on the potential GHJ ETL demonstrate an efficiency of 18.08% with less hysteresis effect, which is due to excellent management of charge transport and recombination.
  PubDate: 2017-05-15T11:46:18.586768-05:
  DOI: 10.1002/adfm.201700878
Multi-Atomic Layers of Metallic Aluminum for Ultralong Life Lithium
Storage with High Volumetric Capacity
- Authors: Jianan Gu; Bin Li, Zhiguo Du, Chao Zhang, Di Zhang, Shubin Yang
  Abstract: Metallic aluminum (Al) have been explored as potential anode materials for lithium storage because of its high theoretical capacity (993 mAh g–1) and low voltage plateaus. Al possesses high electric conductivity, low cost and environmental friendliness. Unfortunately, Al suffers from huge volume change (>100%) during the lithiation/delithiation process, which inevitably results in the pulverization of electrode and rapid capacity decay during cycling processes. To circumvent above issues, a simple but efficient strategy is demonstrated to fabricate free-standing multi-atomic layers of metallic Al by harnessing the good ductility of Al under pressure. The resultant multi-atomic Al layers are ultrathin, ≈3 nm, and have a large aspect ratio. Such unique features enable multi-atomic Al nanosheets to construct uniform and compact films with graphene. Thus, the hybrid films with different ratios are achieved, in which the notorious volume change of metallic Al can be efficiently circumvented via the good flexibility of graphene, and the density of whole electrode can be significantly enhanced. As a consequence, the optimized multi-atomic Al layers-graphene (AlL-G) film exhibits a very high volumetric capacity of 1089 mAh cm–3, high-rate capability and ultralong cycle life up to 20 000 cycles for lithium storage.Multi-atomic layers of metallic aluminum (Al) are successfully fabricated using a rolling method under high pressure. These ultrathin Al nanosheets could construct uniform films with graphene. The volume change of metallic Al can be alleviated via the flexibility of graphene, leading to a novel lithium-ion battery anode with high volumetric capacity, high-rate capability, and ultralong cyclic life up to 20 000 cycles.
  PubDate: 2017-05-15T11:46:13.947937-05:
  DOI: 10.1002/adfm.201700840
Improved Interfacial Floatability of Superhydrophobic/Superhydrophilic
Janus Sheet Inspired by Lotus Leaf
- Authors: Yuyan Zhao; Cunming Yu, Hao Lan, Moyuan Cao, Lei Jiang
  Abstract: Interfacial materials exhibiting superwettability have emerged as important tools for solving the real-world issues, such as oil-spill cleanup, fog harvesting, etc. The Janus superwettability of lotus leaf inspires the design of asymmetric interface materials using the superhydrophobic/superhydrophilic binary cooperative strategy. Here, the presented Janus copper sheet, composed of a superhydrophobic upper surface and a superhydrophilic lower surface, is able to be steadily fixed at the air/water interfaces, showing improved interfacial floatability. Compared with the floatable superhydrophobic substrate, the Janus sheet not only floats on but also attaches to the air–water interface. Similar results on Janus sheet are discovered at other multiphase interfaces such as hexane/water and water/CCl4 interfaces. In accordance with the improved stability and antirotation property, the microboat constructed by a Janus sheet shows the reliable navigating ability even under turbulent water flow. This contribution should unlock more functions of Janus interface materials, and extend the application scope of the binary cooperative materials system with superwettability.Inspired by the cooperative superwettability of a lotus leaf, it is demonstrated that a Janus sheet exhibiting versatile wettability can be stably fixed at multiphase interfaces. Based on the superhydrophobic/superhydrophilic binary cooperative effect, the Janus sheet floats on and tightly adheres to the interfaces.
  PubDate: 2017-05-15T11:46:02.475221-05:
  DOI: 10.1002/adfm.201701466
Modulating the Ferromagnet/Molecule Spin Hybridization Using an Artificial
Magnetoelectric
- Authors: Michał Studniarek; Salia Cherifi-Hertel, Etienne Urbain, Ufuk Halisdemir, Rémi Arras, Beata Taudul, Filip Schleicher, Marie Hervé, Charles-Henri Lambert, Abbass Hamadeh, Loïc Joly, Fabrice Scheurer, Guy Schmerber, Victor Da Costa, Bénédicte Warot-Fonrose, Cécile Marcelot, Olivia Mauguin, Ludovic Largeau, Florian Leduc, Fadi Choueikani, Edwige Otero, Wulf Wulfhekel, Jacek Arabski, Philippe Ohresser, Wolfgang Weber, Eric Beaurepaire, Samy Boukari, Martin Bowen
  Abstract: Spin-polarized charge transfer at the interface between a ferromagnetic (FM) metal and a molecule can lead to ferromagnetic coupling and to a high spin polarization at room temperature. The magnetic properties of these interfaces can not only alter those of the ferromagnet but can also stabilize molecular spin chains with interesting opportunities toward quantum computing. With the aim to enhance an organic spintronic device's functionality, external control over this spin polarization may thus be achieved by altering the ferromagnet/molecule interface's magnetic properties. To do so, the magnetoelectric properties of an underlying ferroelectric/ferromagnetic interface are utilized. Switching the ferroelectric polarization state of a PbZr0.2Ti0.8O3 (PZT) bottom layer within a PZT/Co/FePc-based (Pc - phthalocyanine) device alters the X-ray magnetic circular dichroism of the Fe site within the phthalocyanine molecular top layer. Thus, how to electrically alter the magnetic properties of an interface with high spin polarization at room temperature is demonstrated. This expands electrical control over spin-polarized FM/molecule interfaces, which is first demonstrated using ferroelectric molecules, to all molecular classes.The interface between a ferromagnetic metal (Co) and a molecule (Fe phthalocyanine) can exhibit high spin polarization at room temperature. To control the magnetic coupling that underscores this promising spintronic property, the magnetoelectric properties at the neighboring interface between an oxide ferroelectric (PZT) and Co are used. This enables electrical control over the spintronic properties of any ferromagnet/molecule interface.
  PubDate: 2017-05-10T06:56:03.393157-05:
  DOI: 10.1002/adfm.201700259