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Journal Cover Advanced Materials
  [SJR: 9.021]   [H-I: 345]   [296 followers]  Follow
   Hybrid Journal Hybrid journal (It can contain Open Access articles)
   ISSN (Print) 0935-9648 - ISSN (Online) 1521-4095
   Published by John Wiley and Sons Homepage  [1589 journals]
  • Underwater Mechanically Robust Oil-Repellent Materials: Combining
           Conflicting Properties Using a Heterostructure
    • Authors: Xiangfu Meng; Miaomiao Wang, Liping Heng, Lei Jiang
      Abstract: The development of underwater mechanically robust oil-repellent materials is important due to the high demand for these materials with the increase in underwater activities. Based on the previous study, a new strategy is demonstrated to prepare underwater mechanically robust oil-repellent materials by combining conflicting properties using a heterostructure, which has a layered hydrophobic interior structure with a columnar hierarchical micro/nanostructure on the surface and a hydrophilic outer structure. The surface hydrophilic layer imparts underwater superoleophobicity and low oil adhesion to the material, which has oil contact angle of larger than 150° and adhesion of lower than 2.8 µN. The stability of the mechanical properties stemming from the interior hydrophobic-layered structure enables the material to withstand high weight loads underwater. The tensile stress and the hardness of such a heterostructure film after 1 month immersion in seawater and pH solution are in the range from 83.92 ± 8.22 to 86.73 ± 7.8 MPa and from 83.88 ± 6.8 to 86.82 ± 5.64 MPa, respectively, which are superior to any underwater oil-repellent material currently reported.Layered heterostructure polyacrylic acid (PAA)/polyvinylidene fluoride–graphene nanosheet composites with a convex hexagonal columnar structure on the surface are prepared. The outer hydrophilic PAA hydrogel coating prevents underwater oil adhesion to the material. The inner hydrophobic layer microstructure endows the material with excellent mechanical properties even after immersion in seawater and at different pH values for 1 month.
      PubDate: 2018-01-19T03:45:55.143991-05:
      DOI: 10.1002/adma.201706634
  • Novel MOF-Derived Co@N-C Bifunctional Catalysts for Highly Efficient
           Zn–Air Batteries and Water Splitting
    • Authors: Mingdao Zhang; Quanbin Dai, Hegen Zheng, Mindong Chen, Liming Dai
      Abstract: Metal–organic frameworks (MOFs) and MOF-derived materials have recently attracted considerable interest as alternatives to noble-metal electrocatalysts. Herein, the rational design and synthesis of a new class of Co@N-C materials (C-MOF-C2-T) from a pair of enantiotopic chiral 3D MOFs by pyrolysis at temperature T is reported. The newly developed C-MOF-C2-900 with a unique 3D hierarchical rodlike structure, consisting of homogeneously distributed cobalt nanoparticles encapsulated by partially graphitized N-doped carbon rings along the rod length, exhibits higher electrocatalytic activities for oxygen reduction and oxygen evolution reactions (ORR and OER) than that of commercial Pt/C and RuO2, respectively. Primary Zn–air batteries based on C-MOF-900 for the oxygen reduction reaction (ORR) operated at a discharge potential of 1.30 V with a specific capacity of 741 mA h gZn–1 under 10 mA cm–2. Rechargeable Zn–air batteries based on C-MOF-C2-900 as an ORR and OER bifunctional catalyst exhibit initial charge and discharge potentials at 1.81 and 1.28 V (2 mA cm–2), along with an excellent cycling stability with no increase in polarization even after 120 h – outperform their counterparts based on noble-metal-based air electrodes. The resultant rechargeable Zn–air batteries are used to efficiently power electrochemical water-splitting systems, demonstrating promising potential as integrated green energy systems for practical applications.A Co@N-C material, derived from new chiral metal–organic frameworks, exhibits excellent bifunctional electrocatalytic activities toward both oxygen reduction and oxygen evolution reactions, along with remarkable performance for primary/rechargeable Zn–air batteries (powering water-splitting systems), outperforming their counterparts based on Pt/C and Pt/C + RuO2, respectively.
      PubDate: 2018-01-19T02:38:10.30078-05:0
      DOI: 10.1002/adma.201705431
  • Efficient, Hysteresis-Free, and Stable Perovskite Solar Cells with ZnO as
           Electron-Transport Layer: Effect of Surface Passivation
    • Authors: Jing Cao; Binghui Wu, Ruihao Chen, Youyunqi Wu, Yong Hui, Bing-Wei Mao, Nanfeng Zheng
      Abstract: The power conversion efficiency of perovskite solar cells (PSCs) has ascended from 3.8% to 22.1% in recent years. ZnO has been well-documented as an excellent electron-transport material. However, the poor chemical compatibility between ZnO and organo-metal halide perovskite makes it highly challenging to obtain highly efficient and stable PSCs using ZnO as the electron-transport layer. It is demonstrated in this work that the surface passivation of ZnO by a thin layer of MgO and protonated ethanolamine (EA) readily makes ZnO as a very promising electron-transporting material for creating hysteresis-free, efficient, and stable PSCs. Systematic studies in this work reveal several important roles of the modification: (i) MgO inhibits the interfacial charge recombination, and thus enhances cell performance and stability; (ii) the protonated EA promotes the effective electron transport from perovskite to ZnO, further fully eliminating PSCs hysteresis; (iii) the modification makes ZnO compatible with perovskite, nicely resolving the instability of ZnO/perovskite interface. With all these findings, PSCs with the best efficiency up to 21.1% and no hysteresis are successfully fabricated. PSCs stable in air for more than 300 h are achieved when graphene is used to further encapsulate the cells.Surface passivation of ZnO by a thin layer of MgO and protonated ethanolamine readily makes ZnO a very promising electron-transporting material for creating efficient, hysteresis-free and stable perovskite solar cells (PSCs). PSCs, stable in air for more than 300 h, are achieved when graphene is used to encapsulate the cells.
      PubDate: 2018-01-19T02:37:40.41877-05:0
      DOI: 10.1002/adma.201705596
  • Piezotronic Tuning of Potential Barriers in ZnO Bicrystals
    • Authors: Peter Keil; Maximilian Trapp, Nikola Novak, Till Frömling, Hans-Joachim Kleebe, Jürgen Rödel
      Abstract: Coupling of magnetic, ferroelectric, or piezoelectric properties with charge transport at oxide interfaces provides the option to revolutionize classical electronics. Here, the modulation of electrostatic potential barriers at tailored ZnO bicrystal interfaces by stress-induced piezoelectric polarization is reported. Specimen design by epitaxial solid-state transformation allows for both optimal polarization vector alignment and tailoring of defect states at a semiconductor–semiconductor interface. Both quantities are probed by transmission electron microscopy. Consequently, uniaxial compressive stress affords a complete reduction of the potential barrier height at interfaces with head-to-head orientation of the piezoelectric polarization vectors and an increase in potential barrier height at interfaces with tail-to-tail orientation. The magnitude of this coupling between mechanical input and electrical transport opens pathways to the design of multifunctional electronic devices like strain triggered transistors, diodes, and stress sensors with feasible applications for human–computer interfacing.An epitaxial solid-state transformation process is applied to create individual ZnO–ZnO interfaces with tailored defect chemistry and polarization vector alignment. The potential barrier height at the interfaces is increased or decreased by stress-induced piezoelectric charges, depending on the orientation of the polarization vectors. A reduction of the barrier height by 86% demonstrates the high applicability for piezotronic applications.
      PubDate: 2018-01-19T02:37:17.016181-05:
      DOI: 10.1002/adma.201705573
  • VO2/TiN Plasmonic Thermochromic Smart Coatings for Room-Temperature
    • Authors: Qi Hao; Wan Li, Huiyan Xu, Jiawei Wang, Yin Yin, Huaiyu Wang, Libo Ma, Fei Ma, Xuchuan Jiang, Oliver G. Schmidt, Paul K. Chu
      Abstract: Vanadium dioxide/titanium nitride (VO2/TiN) smart coatings are prepared by hybridizing thermochromic VO2 with plasmonic TiN nanoparticles. The VO2/TiN coatings can control infrared (IR) radiation dynamically in accordance with the ambient temperature and illumination intensity. It blocks IR light under strong illumination at 28 °C but is IR transparent under weak irradiation conditions or at a low temperature of 20 °C. The VO2/TiN coatings exhibit a good integral visible transmittance of up to 51% and excellent IR switching efficiency of 48% at 2000 nm. These unique advantages make VO2/TiN promising as smart energy-saving windows.Thermochromic vanadium oxide (VO2) film is coated on titanium nitrate (TiN) plasmonic nanoparticles to fabricate a hybrid VO2/TiN smart coating. This novel coating can intelligently control the infrared (IR) radiation under room-temperature conditions by reflecting the IR radiation at a high temperature while allowing most of the radiation to go through at a low temperature.
      PubDate: 2018-01-19T02:36:59.086403-05:
      DOI: 10.1002/adma.201705421
  • Biodegradable Electronic Systems in 3D, Heterogeneously Integrated Formats
    • Authors: Jan-Kai Chang; Hui-Ping Chang, Qinglei Guo, Jahyun Koo, Chih-I Wu, John A. Rogers
      Abstract: Biodegradable electronic systems represent an emerging class of technology with unique application possibilities, from temporary biomedical implants to “green” consumer gadgets. This paper introduces materials and processing methods for 3D, heterogeneously integrated devices of this type, with various functional examples in sophisticated forms of silicon-based electronics. Specifically, techniques for performing multilayer assembly by transfer printing and for fabricating layer-to-layer vias and interconnects by lithographic procedures serve as routes to biodegradable, 3D integrated circuits composed of functional building blocks formed using specialized approaches or sourced from commercial semiconductor foundries. Demonstration examples range from logic gates and analog circuits that undergo functional transformation by transience to systems that integrate multilayer resistive sensors for in situ, continuous electrical monitoring of the processes of transience. The results significantly expand the scope of engineering options for biodegradable electronics and other types of transient microsystem technologies.Transient 3D electronic systems follow from use of biodegradable materials and deterministic assembly of foundry-compatible microelectronic components. Physical and electrical transience allow functional transformation upon system dissolution and disintegration, thereby expanding the scope of engineering options for biodegradable electronics and other types of transient microsystem technologies.
      PubDate: 2018-01-19T02:36:41.963508-05:
      DOI: 10.1002/adma.201704955
  • Engineered and Laser-Processed Chitosan Biopolymers for Sustainable and
           Biodegradable Triboelectric Power Generation
    • Authors: Ruoxing Wang; Shengjie Gao, Zhen Yang, Yule Li, Weinong Chen, Benxin Wu, Wenzhuo Wu
      Abstract: Recent advances achieved in triboelectric nanogenerators (TENG) focus on boosting power generation and conversion efficiency. Nevertheless, obstacles concerning economical and biocompatible utilization of TENGs continue to prevail. Being an abundant natural biopolymer from marine crustacean shells, chitosan enables exciting opportunities for low-cost, biodegradable TENG applications in related fields. Here, the development of biodegradable and flexible TENGs based on chitosan is presented for the first time. The physical and chemical properties of the chitosan nanocomposites are systematically studied and engineered for optimized triboelectric power generation, transforming the otherwise wasted natural materials into functional energy devices. The feasibility of laser processing of constituent materials is further explored for the first time for engineering the TENG performance. The laser treatment of biopolymer films offers a potentially promising scheme for surface engineering in polymer-based TENGs. The chitosan-based TENGs present efficient energy conversion performance and tunable biodegradation rate. Such a new class of TENGs derived from natural biomaterials may pave the way toward the economically viable and ecologically friendly production of flexible TENGs for self-powered nanosystems in biomedical and environmental applications.Chitosan as an abundant natural biopolymer, is enigneered by mixing with other natural components and surface laser treatment for optimized triboelectric nanogenerator (TENG) performance. The chitosan-based TENGs enable exciting opportunities for low-cost, biodegradable TENG applications in related fields, transforming the otherwise wasted natural materials into functional energy devices.
      PubDate: 2018-01-19T02:31:13.855141-05:
      DOI: 10.1002/adma.201706267
  • A Hierarchical Z-Scheme α-Fe2O3/g-C3N4 Hybrid for Enhanced
           Photocatalytic CO2 Reduction
    • Authors: Zhifeng Jiang; Weiming Wan, Huaming Li, Shouqi Yuan, Huijun Zhao, Po Keung Wong
      Abstract: The challenge in the artificial photosynthesis of fossil resources from CO2 by utilizing solar energy is to achieve stable photocatalysts with effective CO2 adsorption capacity and high charge-separation efficiency. A hierarchical direct Z-scheme system consisting of urchin-like hematite and carbon nitride provides an enhanced photocatalytic activity of reduction of CO2 to CO, yielding a CO evolution rate of 27.2 µmol g−1 h−1 without cocatalyst and sacrifice reagent, which is>2.2 times higher than that produced by g-C3N4 alone (10.3 µmol g−1 h−1). The enhanced photocatalytic activity of the Z-scheme hybrid material can be ascribed to its unique characteristics to accelerate the reduction process, including: (i) 3D hierarchical structure of urchin-like hematite and preferable basic sites which promotes the CO2 adsorption, and (ii) the unique Z-scheme feature efficiently promotes the separation of the electron–hole pairs and enhances the reducibility of electrons in the conduction band of the g-C3N4. The origin of such an obvious advantage of the hierarchical Z-scheme is not only explained based on the experimental data but also investigated by modeling CO2 adsorption and CO adsorption on the three different atomic-scale surfaces via density functional theory calculation. The study creates new opportunities for hierarchical hematite and other metal-oxide-based Z-scheme system for solar fuel generation.A hierarchical direct Z-scheme hybrid for the photocatalytic reduction of CO2 without using any sacrifice agent or cocatalyst is developed by combining urchin-like α-Fe2O3 and g-C3N4. The coupling of the urchin-like α-Fe2O3 with g-C3N4 can trigger significantly improved photoreduction activity of CO2 to form CO.
      PubDate: 2018-01-19T02:30:49.683844-05:
      DOI: 10.1002/adma.201706108
  • Nanocrystalline Precursors for the Co-Assembly of Crack-Free Metal Oxide
           Inverse Opals
    • Authors: Katherine R. Phillips; Tanya Shirman, Elijah Shirman, Anna V. Shneidman, Theresa M. Kay, Joanna Aizenberg
      Abstract: Inorganic microstructured materials are ubiquitous in nature. However, their formation in artificial self-assembly systems is challenging as it involves a complex interplay of competing forces during and after assembly. For example, colloidal assembly requires fine-tuning of factors such as the size and surface charge of the particles and electrolyte strength of the solvent to enable successful self-assembly and minimize crack formation. Co-assembly of templating colloidal particles together with a sol–gel matrix precursor material helps to release stresses that accumulate during drying and solidification, as previously shown for the formation of high-quality inverse opal (IO) films out of amorphous silica. Expanding this methodology to crystalline materials would result in microscale architectures with enhanced photonic, electronic, and catalytic properties. This work describes tailoring the crystallinity of metal oxide precursors that enable the formation of highly ordered, large-area (mm2) crack-free titania, zirconia, and alumina IO films. The same bioinspired approach can be applied to other crystalline materials as well as structures beyond IOs.Beautifully colored, highly ordered, crack-free photonic structures from a variety of metal oxides are unlocked using rationally designed metal oxide nanocrystal precursors. The synthetic strategy is inspired by an iconic principle in biomineralization in which precursors to mineralized tissues contain both amorphous and crystalline components, allowing this mixed phase to accommodate stresses occurring during the self-assembly process.
      PubDate: 2018-01-19T02:27:15.152504-05:
      DOI: 10.1002/adma.201706329
  • Accelerated Hydrogen Evolution Kinetics on NiFe-Layered Double Hydroxide
           Electrocatalysts by Tailoring Water Dissociation Active Sites
    • Authors: Guangbo Chen; Tao Wang, Jian Zhang, Pan Liu, Hanjun Sun, Xiaodong Zhuang, Mingwei Chen, Xinliang Feng
      Abstract: Owing to its earth abundance, low kinetic overpotential, and superior stability, NiFe-layered double hydroxide (NiFe-LDH) has emerged as a promising electrocatalyst for catalyzing water splitting, especially oxygen evolution reaction (OER), in alkaline solutions. Unfortunately, as a result of extremely sluggish water dissociation kinetics (Volmer step), hydrogen evolution reaction (HER) activity of the NiFe-LDH is rather poor in alkaline environment. Here a novel strategy is demonstrated for substantially accelerating the hydrogen evolution kinetics of the NiFe-LDH by partially substituting Fe atoms with Ru. In a 1 m KOH solution, the as-synthesized Ru-doped NiFe-LDH nanosheets (NiFeRu-LDH) exhibit excellent HER performance with an overpotential of 29 mV at 10 mA cm−2, which is much lower than those of noble metal Pt/C and reported electrocatalysts. Both experimental and theoretical results reveal that the introduction of Ru atoms into NiFe-LDH can efficiently reduce energy barrier of the Volmer step, eventually accelerating its HER kinetics. Benefitting from its outstanding HER activity and remained excellent OER activity, the NiFeRu-LDH steadily drives an alkaline electrolyzer with a current density of 10 mA cm−2 at a cell voltage of 1.52 V, which is much lower than the values for Pt/C–Ir/C couple and state-of-the-art overall water-splitting electrocatalysts.A novel approach is demonstrated to substantially speed up the sluggish hydrogen evolution reaction (HER) kinetics on the NiFe-layered double hydroxide (LDH) by tailoring its water dissociation active sites in alkaline solutions. The resultant Ru-doped NiFe-LDH nanosheet exhibits a greatly enhanced HER activity in alkaline solution, which is superior to those of Pt/C and state-of-the-art Pt-free electrocatalysts.
      PubDate: 2018-01-19T02:26:37.06399-05:0
      DOI: 10.1002/adma.201706279
  • Realizing zT of 2.3 in Ge1−x−ySbxInyTe via Reducing the
           Phase-Transition Temperature and Introducing Resonant Energy Doping
    • Authors: Min Hong; Zhi-Gang Chen, Lei Yang, Yi-Chao Zou, Matthew S. Dargusch, Hao Wang, Jin Zou
      Abstract: GeTe with rhombohedral-to-cubic phase transition is a promising lead-free thermoelectric candidate. Herein, theoretical studies reveal that cubic GeTe has superior thermoelectric behavior, which is linked to (1) the two valence bands to enhance the electronic transport coefficients and (2) stronger enharmonic phonon–phonon interactions to ensure a lower intrinsic thermal conductivity. Experimentally, based on Ge1−xSbxTe with optimized carrier concentration, a record-high figure-of-merit of 2.3 is achieved via further doping with In, which induces the distortion of the density of states near the Fermi level. Moreover, Sb and In codoping reduces the phase-transition temperature to extend the better thermoelectric behavior of cubic GeTe to low temperature. Additionally, electronic microscopy characterization demonstrates grain boundaries, a high-density of stacking faults, and nanoscale precipitates, which together with the inevitable point defects result in a dramatically decreased thermal conductivity. The fundamental investigation and experimental demonstration provide an important direction for the development of high-performance Pb-free thermoelectric materials.An ultrahigh figure-of-merit of 2.3 is achieved in Ge0.89Sb0.1In0.01Te through enhancing power-factor and decreasing thermal conductivity. The enhanced power-factor is caused by the optimized carrier concentration, reduced phase-transition temperature, and introduced resonant-energy doping. The decreased thermal conductivity is due to the enhanced phonon scatterings by the intrinsically deformed phonon transport and the externally induced phonon scattering sources.
      PubDate: 2018-01-19T02:25:58.101441-05:
      DOI: 10.1002/adma.201705942
  • Superfast Room-Temperature Activation of SnO2 Thin Films via Atmospheric
    • Authors: Haejun Yu; Hye-In Yeom, Jong Woo Lee, Kisu Lee, Doyk Hwang, Juyoung Yun, Jaehoon Ryu, Jungsup Lee, Sohyeon Bae, Seong Keun Kim, Jyongsik Jang
      Abstract: The power conversion efficiency (PCE) of perovskite solar cells (PSCs) has now exceeded 20%; thus, research focus has shifted to establishing the foundations for commercialization. One of the pivotal themes is to curtail the overall fabrication time, to reduce unit cost, and mass-produce PSCs. Additionally, energy dissipation during the thermal annealing (TA) stage must be minimized by realizing a genuine low-temperature (LT) process. Here, tin oxide (SnO2) thin films (TFs) are formulated at extremely high speed, within 5 min, under an almost room-temperature environment (
      PubDate: 2018-01-19T02:09:27.285466-05:
      DOI: 10.1002/adma.201704825
  • Dual Drug Backboned Shattering Polymeric Theranostic Nanomedicine for
           Synergistic Eradication of Patient-Derived Lung Cancer
    • Authors: Yuwei Cong; Haihua Xiao, Hejian Xiong, Zigui Wang, Jianxun Ding, Chan Li, Xuesi Chen, Xing-Jie Liang, Dongfang Zhou, Yubin Huang
      Abstract: Most of the current nanoparticle-based therapeutics worldwide failing in clinical trials face three major challenges: (i) lack of an optimum drug delivery platform with precise composition, (ii) lack of a method of directly monitoring the fate of a specific drug rather than using any other labelling molecules as a compromise, and (iii) lack of reliable cancer models with high fidelity for drug screen and evaluation. Here, starting from a PP2A inhibitor demethylcantharidin (DMC) and cisplatin, the design of a dual sensitive dual drug backboned shattering polymer (DDBSP) with exact composition at a fixed DMC/Pt ratio for precise nanomedicine is shown. DDBSP self-assembled nanoparticle (DD-NP) can be triggered intracellularly to break down in a chain-shattering manner to release the dual drugs payload. Moreover, DD-NP with extremely high Pt heavy metal content in the polymer chain can directly track the drug itself via Pt-based drug-mediated computer tomography and ICP-MS both in vitro and in vivo. Finally, DD-NP is used to eradicate the tumor burden on a high-fidelity patient-derived lung cancer model for the first time.Dual drug backboned shattering polymeric theranostic nanomedicine that can be triggered intracellularly to breakdown in a chain-shattering manner to release the dual drugs payload is developed. It can directly track the drug itself via Pt-based drug-mediated computer tomography and eradicate the tumor burden on a high-fidelity patient-derived lung cancer model.
      PubDate: 2018-01-19T02:07:12.174886-05:
      DOI: 10.1002/adma.201706220
  • Self-Calibrating Mechanochromic Fluorescent Polymers Based on Encapsulated
           Excimer-Forming Dyes
    • Authors: Céline Calvino; Anirvan Guha, Christoph Weder, Stephen Schrettl
      Abstract: While mechanochemical transduction principles are omnipresent in nature, mimicking these in artificial materials is challenging. The ability to reliably detect the exposure of man-made objects to mechanical forces is, however, of great interest for many applications, including structural health monitoring and tamper-proof packaging. A useful concept to achieve mechanochromic responses in polymers is the integration of microcapsules, which rupture upon deformation and release a payload causing a visually detectable response. Herein, it is reported that this approach can be used to create mechanochromic fluorescent materials that show a direct and ratiometric response to mechanical deformation. This can be achieved by filling poly(urea-formaldehyde) microcapsules with a solution of a photoluminescent aggregachromic cyano-substituted oligo(p-phenylene vinylene) and embedding these particles in poly(dimethylsiloxane). The application of mechanical force by way of impact, incision, or tensile deformation opens the microcapsules and releases the fluorophore in the damaged area. Due to excimer formation, the subsequent aggregation of the dye furnishes a detectable fluorescence color change. With the emission from unopened microcapsules as built-in reference, the approach affords materials that are self-calibrating. This new concept appears to be readily applicable to a range of polymer matrices and allows for the straightforward assessment of their structural integrity.Failure detection in polymeric materials is achieved by incorporating microcapsules filled with solutions of excimer-forming fluorescent dyes. Deformation of such materials breaks the microcapsules and a readily detectable change of the fluorescence color occurs upon release and aggregation of the dye. The emission of undamaged capsules serves as reference, enabling ratiometric measurements and therewith quantitative assessments of mechanical impact.
      PubDate: 2018-01-18T06:06:59.487329-05:
      DOI: 10.1002/adma.201704603
  • Flexoelectricity in Bones
    • Authors: Fabian Vasquez-Sancho; Amir Abdollahi, Dragan Damjanovic, Gustau Catalan
      Abstract: Bones generate electricity under pressure, and this electromechanical behavior is thought to be essential for bone's self-repair and remodeling properties. The origin of this response is attributed to the piezoelectricity of collagen, which is the main structural protein of bones. In theory, however, any material can also generate voltages in response to strain gradients, thanks to the property known as flexoelectricity. In this work, the flexoelectricity of bone and pure bone mineral (hydroxyapatite) are measured and found to be of the same order of magnitude; the quantitative similarity suggests that hydroxyapatite flexoelectricity is the main source of bending-induced polarization in cortical bone. In addition, the measured flexoelectric coefficients are used to calculate the (flexo)electric fields generated by cracks in bone mineral. The results indicate that crack-generated flexoelectricity is theoretically large enough to induce osteocyte apoptosis and thus initiate the crack-healing process, suggesting a central role of flexoelectricity in bone repair and remodeling.The generation of electricity by bending (flexoelectricity) is measured in bones and bone mineral, hydroxyapatite. The measured flexoelectric coefficients are then used to calculate the flexoelectric fields around cracks in hydroxyapatite. The results indicate that crack-induced flexoelectricity is sufficiently large to have an important physiological effect as the signaling mechanism for the healing of bone fractures.
      PubDate: 2018-01-18T06:05:49.901731-05:
      DOI: 10.1002/adma.201705316
  • Quinoline-Flanked Diketopyrrolopyrrole Copolymers Breaking through
           Electron Mobility over 6 cm2 V−1 s−1 in Flexible Thin Film Devices
    • Authors: Zhenjie Ni; Huanli Dong, Hanlin Wang, Shang Ding, Ye Zou, Qiang Zhao, Yonggang Zhen, Feng Liu, Lang Jiang, Wenping Hu
      Abstract: Herein, the design and synthesis of novel π-extended quinoline-flanked diketopyrrolopyrrole (DPP) [abbreviated as QDPP] motifs and corresponding copolymers named PQDPP-T and PQDPP-2FT for high performing n-type organic field-effect transistors (OFETs) in flexible organic thin film devices are reported. Serving as DPP-flankers in backbones, quinoline is found to effectively tune copolymer optoelectric properties. Compared with TDPP and pyridine-flanked DPP (PyDPP) analogs, widened bandgaps and strengthened electron deficiency are achieved. Moreover, both hole and electron mobility are improved two orders of magnitude compared to those of PyDPP analogs (PPyDPP-T and PPyDPP-2FT). Notably, featuring an all-acceptor-incorporated backbone, PQDPP-2FT exhibits electron mobility of 6.04 cm2 V−1 s−1, among the highest value in OFETs fabricated on flexible substrates to date. Moreover, due to the widened bandgap and strengthened electron deficiency of PQDPP, n-channel on/off ratio over 105 with suppressed hole transport is first realized in the ambipolar DPP-based copolymers.The design and synthesis of quinoline-flanked DPP (QDPP) motifs and corresponding copolymers named PQDPP-T and PQDPP-2FT with µe up to 6.04 cm2 V−1 s−1, which is the highest mobility in organic field-effect transistors (OFETs) fabricated on flexible substrates to date, are reported. PQDPPs present one of the few promising candidates for n-type dominant DPP polymers for OFET utilization.
      PubDate: 2018-01-18T06:01:26.61808-05:0
      DOI: 10.1002/adma.201704843
  • A Single-Molecule Propyne Trap: Highly Efficient Removal of Propyne from
           Propylene with Anion-Pillared Ultramicroporous Materials
    • Authors: Lifeng Yang; Xili Cui, Qiwei Yang, Siheng Qian, Hui Wu, Zongbi Bao, Zhiguo Zhang, Qilong Ren, Wei Zhou, Banglin Chen, Huabin Xing
      Abstract: Propyne/propylene (C3H4/C3H6) separation is a critical process for the production of polymer-grade C3H6. However, optimization of the structure of porous materials for the highly efficient removal of C3H4 from C3H6 remains challenging due to their similar structures and ultralow C3H4 concentration. Here, it is first reported that hybrid ultramicroporous materials with pillared inorganic anions (SiF62− = SIFSIX, NbOF52− = NbOFFIVE) can serve as highly selective C3H4 traps for the removal of trace C3H4 from C3H6. Especially, it is revealed that the pyrazine-based ultramicroporous material with square grid structure for which the pore shape and functional site disposition can be varied in 0.1–0.5 Å scale to match both the shape and interacting sites of guest molecule is an interesting single-molecule trap for C3H4 molecule. The pyrazine-based single-molecule trap enables extremely high C3H4 uptake under ultralow concentration (2.65 mmol g−1 at 3000 ppm, one C3H4 per unit cell) and record selectivity over C3H6 at 298 K (>250). The single-molecule binding mode for C3H4 within ultramicroporous material is validated by X-ray diffraction experiments and modeling studies. The breakthrough experiments confirm that anion-pillared ultramicroporous materials set new benchmarks for the removal of ultralow concentration C3H4 (1000 ppm on SIFSIX-3-Ni, and 10 000 ppm on SIFSIX-2-Cu-i) from C3H6.By precisely tuning the pore size and functional sites disposition of anion-pillared ultramicroporous materials at the 0.1–0.5 Å scale for the best match of both of the shape and interacting sites of propyne, a pyrazine-based material with square grid structure is revealed to be able to serve as a single-molecule propyne trap, affording an efficient capture of trace propyne from propylene.
      PubDate: 2018-01-18T06:01:00.504585-05:
      DOI: 10.1002/adma.201705374
  • Lipid and Nucleic Acid Chemistries: Combining the Best of Both Worlds to
           Construct Advanced Biomaterials
    • Authors: Julie Baillet; Valérie Desvergnes, Aladin Hamoud, Laurent Latxague, Philippe Barthélémy
      Abstract: Hybrid synthetic amphiphilic biomolecules are emerging as promising supramolecular materials for biomedical and technological applications. Herein, recent progress in the field of nucleic acid based lipids is highlighted with an emphasis on their molecular design, synthesis, supramolecular properties, physicochemical behaviors, and applications in the field of health science and technology. In the first section, the design and the study of nucleolipids are in focus and then the glyconucleolipid family is discussed. In the last section, recent contributions of responsive materials involving nucleolipids and their use as smart drug delivery systems are discussed. The supramolecular materials generated by nucleic acid based lipids open new challenges for biomedical applications, including the fields of medicinal chemistry, biosensors, biomaterials for tissue engineering, drug delivery, and the decontamination of nanoparticles.Hybrid molecules combining nucleic acid structures with lipids have recently received increasing attention as a new class of supramolecular biomaterials. An overview of the latest studies on their chemical and biological properties is presented, including several biomedical applications ranging from medicinal chemistry to biomaterials. Some suggestions for developing these types of soft materials in the near future are also proposed.
      PubDate: 2018-01-17T11:45:04.765474-05:
      DOI: 10.1002/adma.201705078
  • A Facile Method to Fabricate Anisotropic Hydrogels with Perfectly Aligned
           Hierarchical Fibrous Structures
    • Authors: Md. Tariful Islam Mredha; Yun Zhou Guo, Takayuki Nonoyama, Tasuku Nakajima, Takayuki Kurokawa, Jian Ping Gong
      Abstract: Natural structural materials (such as tendons and ligaments) are comprised of multiscale hierarchical architectures, with dimensions ranging from nano- to macroscale, which are difficult to mimic synthetically. Here a bioinspired, facile method to fabricate anisotropic hydrogels with perfectly aligned multiscale hierarchical fibrous structures similar to those of tendons and ligaments is reported. The method includes drying a diluted physical hydrogel in air by confining its length direction. During this process, sufficiently high tensile stress is built along the length direction to align the polymer chains and multiscale fibrous structures (from nano- to submicro- to microscale) are spontaneously formed in the bulk material, which are well-retained in the reswollen gel. The method is useful for relatively rigid polymers (such as alginate and cellulose), which are susceptible to mechanical signal. By controlling the drying with or without prestretching, the degree of alignment, size of superstructures, and the strength of supramolecular interactions can be tuned, which sensitively influence the strength and toughness of the hydrogels. The mechanical properties are comparable with those of natural ligaments. This study provides a general strategy for designing hydrogels with highly ordered hierarchical structures, which opens routes for the development of many functional biomimetic materials for biomedical applications.Anisotropic hydrogels with perfectly aligned hierarchical fibrous structures are fabricated by a simple method. Drying a physical hydrogel by confining its length direction generates a 1D tensile force that controls polymeric alignment and supramolecular interactions. A tunable structure and mechanical properties are realized in different types of rigid polymeric hydrogels and the properties are comparable with those of natural ligaments.
      PubDate: 2018-01-17T11:43:38.714297-05:
      DOI: 10.1002/adma.201704937
  • Cross-Linking of Thiolated Paclitaxel–Oligo(p-phenylene vinylene)
           Conjugates Aggregates inside Tumor Cells Leads to “Chemical Locks”
           That Increase Drug Efficacy
    • Authors: Lingyun Zhou; Fengting Lv, Libing Liu, Guizhi Shen, Xuehai Yan, Guillermo C. Bazan, Shu Wang
      Abstract: How to reduce the resistance of certain tumor cells to paclitaxel (PTX) and related taxoid anticancer drugs is a major challenge for improving cure rates. An oligo(p-phenylenevinylene) unit with thiol groups and a PTX unit (OPV-S-PTX), which enhances drug efficacy and reverses resistance is thus designed. The mechanism involves diffusion of OPV-S-PTX into the cell, where π–π interactions lead to aggregation. Cross-linking of the aggregates via oxidation of thiol groups is favored in tumor cells because of the higher reactive oxygen species (ROS) concentration. Cross-linked aggregates “chemically lock” the multichromophore particle for a more persistent effect. The IC50 of OPV-S-PTX for tumor cell line A549 is reduced down to 0.33 × 10−9m from that observed for PTX itself (41 × 10−9m). Enhanced efficacy by OPV-S-PTX is proposed to proceed via acceleration of microtubule bundle formation. A549/T-inoculated xenograft mice experiments reveal suppression of tumor growth upon OPV-S-PTX treatment. Altogether, these results show that the internal cross-linking of OPV-S-PTX through ROS provides a means to discriminate between tumor and healthy cells and the formation of the chemically locked particles enhances drug efficacy and helps in reducing resistance.A paclitaxel-oligo(p-phenylene vinylene) conjugate (OPV-S-PTX) is designed to enhance drug efficacy and reverse resistance. The conjugates self-assemble inside cells and subsequently cross-link via reactive oxygen species (ROS). The IC50 exhibited by OPV-S-PTX toward tumor cell line A549 is significantly reduced in comparison to that of PTX itself, together with suppression of tumor growth in live animals. The new molecular system and overall mechanism of action provide an attractive approach to combat PTX resistance, while simultaneously reducing undesirable side effects on normal cells.
      PubDate: 2018-01-17T03:11:45.361719-05:
      DOI: 10.1002/adma.201704888
  • Bottom-Up Fabrication of Semiconductive Metal–Organic Framework
           Ultrathin Films
    • Authors: Víctor Rubio-Giménez; Marta Galbiati, Javier Castells-Gil, Neyvis Almora-Barrios, José Navarro-Sánchez, Garin Escorcia-Ariza, Michele Mattera, Thomas Arnold, Jonathan Rawle, Sergio Tatay, Eugenio Coronado, Carlos Martí-Gastaldo
      Abstract: Though generally considered insulating, recent progress on the discovery of conductive porous metal–organic frameworks (MOFs) offers new opportunities for their integration as electroactive components in electronic devices. Compared to classical semiconductors, these metal–organic hybrids combine the crystallinity of inorganic materials with easier chemical functionalization and processability. Still, future development depends on the ability to produce high-quality films with fine control over their orientation, crystallinity, homogeneity, and thickness. Here self-assembled monolayer substrate modification and bottom-up techniques are used to produce preferentially oriented, ultrathin, conductive films of Cu-CAT-1. The approach permits to fabricate and study the electrical response of MOF-based devices incorporating the thinnest MOF film reported thus far (10 nm thick).Preferably oriented, ultrathin, semiconductive films of the metal–organic framework (MOF) Cu-CAT-1 by using self-assembled monolayer substrate modification and bottom-up techniques. The approach enables fabrication and study of the electrical response of MOF-based devices incorporating the thinnest MOF film reported thus far (10 nm thick).
      PubDate: 2018-01-17T03:11:03.597564-05:
      DOI: 10.1002/adma.201704291
  • Real-Time and High-Resolution Bioimaging with Bright Aggregation-Induced
           Emission Dots in Short-Wave Infrared Region
    • Authors: Ji Qi; Chaowei Sun, Abudureheman Zebibula, Hequn Zhang, Ryan T. K. Kwok, Xinyuan Zhao, Wang Xi, Jacky W. Y. Lam, Jun Qian, Ben Zhong Tang
      Abstract: Fluorescence imaging in the spectral region beyond the conventional near-infrared biological window (700–900 nm) can theoretically afford high resolution and deep tissue penetration. Although some efforts have been devoted to developing a short-wave infrared (SWIR; 900–1700 nm) imaging modality in the past decade, long-wavelength biomedical imaging is still suboptimal owing to the unsatisfactory materials properties of SWIR fluorophores. Taking advantage of organic dots based on an aggregation-induced emission luminogen (AIEgen), herein microscopic vasculature imaging of brain and tumor is reported in living mice in the SWIR spectral region. The long-wavelength emission of AIE dots with certain brightness facilitates resolving brain capillaries with high spatial resolution (≈3 µm) and deep penetration (800 µm). Owning to the deep penetration depth and real-time imaging capability, in vivo SWIR microscopic angiography exhibits superior resolution in monitoring blood–brain barrier damage in mouse brain, and visualizing enhanced permeability and retention effect in tumor sites. Furthermore, the AIE dots show good biocompatibility, and no noticeable abnormalities, inflammations or lesions are observed in the main organs of the mice. This work will inspire new insights on development of advanced SWIR techniques for biomedical imaging.By employing bright NIR aggregation-induced emission (AIE) dots and short-wave infrared imaging systems, brain capillaries with high spatial resolution (≈3 µm) and deep penetration (800 µm) in living mice are resolved. Owning to the large penetration depth and real-time imaging capability, AIE dots enable superior resolution in probing blood–brain barrier damage in the mouse brain, and visualizing enhanced permeability and retention effect in tumor sites.
      PubDate: 2018-01-17T03:06:23.535687-05:
      DOI: 10.1002/adma.201706856
  • Ultrafast Laser-Shock-Induced Confined Metaphase Transformation for Direct
           Writing of Black Phosphorus Thin Films
    • Authors: Gang Qiu; Qiong Nian, Maithilee Motlag, Shengyu Jin, Biwei Deng, Yexin Deng, Adam R. Charnas, Peide D. Ye, Gary J. Cheng
      Abstract: Few-layer black phosphorus (BP) has emerged as one of the most promising candidates for post-silicon electronic materials due to its outstanding electrical and optical properties. However, lack of large-scale BP thin films is still a major roadblock to further applications. The most widely used methods for obtaining BP thin films are mechanical exfoliation and liquid exfoliation. Herein, a method of directly synthesizing continuous BP thin films with the capability of patterning arbitrary shapes by employing ultrafast laser writing with confinement is reported. The physical mechanism of confined laser metaphase transformation is understood by molecular dynamics simulation. Ultrafast laser ablation of BP layer under confinement can induce transient nonequilibrium high-temperature and high-pressure conditions for a few picoseconds. Under optimized laser intensity, this process induces a metaphase transformation to form a crystalline BP thin film on the substrate. Raman spectroscopy, atomic force microscopy, and transmission electron microscopy techniques are utilized to characterize the morphology of the resulting BP thin films. Field-effect transistors are fabricated on the BP films to study their electrical properties. This unique approach offers a general methodology to mass produce large-scale patterned BP films with a one-step manufacturing process that has the potential to be applied to other 2D materials.A method of directly synthesizing continuous black phosphorus (BP) thin films with arbitrary patterned shapes by employing ultrafast laser writing with confinement is reported. Ultrafast laser ablation of a BP layer under confinement can generate transient nonequilibrium high-temperature and high-pressure conditions for a few picoseconds, which induce a metaphase transformation to form a crystalline BP thin film on the substrate.
      PubDate: 2018-01-16T09:37:28.529584-05:
      DOI: 10.1002/adma.201704405
  • Orientation-Dependent Strain Relaxation and Chemical Functionalization of
           Graphene on a Cu(111) Foil
    • Authors: Bao-Wen Li; Da Luo, Liyan Zhu, Xu Zhang, Sunghwan Jin, Ming Huang, Feng Ding, Rodney S. Ruoff
      Abstract: Epitaxial graphene grown on single crystal Cu(111) foils by chemical vapor deposition is found to be free of wrinkles and under biaxial compressive strain. The compressive strain in the epitaxial regions (0.25–0.40%) is higher than regions where the graphene is not epitaxial with the underlying surface (0.20–0.25%). This orientation-dependent strain relaxation is through the loss of local adhesion and the generation of graphene wrinkles. Density functional theory calculations suggest a large frictional force between the epitaxial graphene and the Cu(111) substrate, and this is therefore an energy barrier to the formation of wrinkles in the graphene. Enhanced chemical reactivity is found in epitaxial graphene on Cu(111) foils as compared to graphene on polycrystalline Cu foils for certain chemical reactions. A higher compressive strain possibly favors lowering the formation energy and/or the energy gap between the initial and transition states, either of which can lead to an increase in chemical reactivity.Wrinkle-free epitaxial graphene is grown on single crystal Cu(111) foil by chemical vapor deposition. The biaxial compressive strain in the epitaxial regions (0.25–0.40%) is higher than regions where the graphene is not epitaxial with the underlying surface (0.20–0.25%). This orientation-dependent strain relaxation is through the loss of local adhesion and the generation of graphene wrinkles.
      PubDate: 2018-01-16T09:31:07.738625-05:
      DOI: 10.1002/adma.201706504
  • Thiazole Imide-Based All-Acceptor Homopolymer: Achieving High-Performance
           Unipolar Electron Transport in Organic Thin-Film Transistors
    • Authors: Yongqiang Shi; Han Guo, Minchao Qin, Jiuyang Zhao, Yuxi Wang, Hang Wang, Yulun Wang, Antonio Facchetti, Xinhui Lu, Xugang Guo
      Abstract: High-performance unipolar n-type polymer semiconductors are critical for advancing the field of organic electronics, which relies on the design and synthesis of new electron-deficient building blocks with good solubilizing capability, favorable geometry, and optimized electrical properties. Herein, two novel imide-functionalized thiazoles, 5,5′-bithiazole-4,4′-dicarboxyimide (BTzI) and 2,2′-bithiazolothienyl-4,4′,10,10′-tetracarboxydiimide (DTzTI), are successfully synthesized. Single crystal analysis and physicochemical study reveal that DTzTI is an excellent building block for constructing all-acceptor homopolymers, and the resulting polymer poly(2,2′-bithiazolothienyl-4,4′,10,10′-tetracarboxydiimide) (PDTzTI) exhibits unipolar n-type transport with a remarkable electron mobility (μe) of 1.61 cm2 V−1 s−1, low off-currents (Ioff) of 10−10−10−11 A, and substantial current on/off ratios (Ion/Ioff) of 107−108 in organic thin-film transistors. The all-acceptor homopolymer shows distinctive advantages over prevailing n-type donor−acceptor copolymers, which suffer from ambipolar transport with high Ioffs> 10−8 A and small Ion/Ioffs < 105. The results demonstrate that the all-acceptor approach is superior to the donor−acceptor one, which results in unipolar electron transport with more ideal transistor performance characteristics.Electron-deficient thiazole imides are synthesized, which enables development of all-acceptor homopolymers. The polymer PDTzTI exhibits a remarkable electron mobility of 1.61 cm2 V−1 s−1 with minimal off-currents of 10−10−10−11 A and substantial current on/off ratios of 107−108 in the saturation regime, thus showing distinctive advantages over traditional donor−acceptor copolymers, which suffer from high off-currents and small on/off ratios.
      PubDate: 2018-01-16T09:30:49.823848-05:
      DOI: 10.1002/adma.201705745
  • 2D PdAg Alloy Nanodendrites for Enhanced Ethanol Electroxidation
    • Authors: Wenjing Huang; Xiaolin Kang, Cheng Xu, Junhua Zhou, Jun Deng, Yanguang Li, Si Cheng
      Abstract: The development of highly active and stable electrocatalysts for ethanol electroxidation is of decisive importance to the successful commercialization of direct ethanol fuel cells. Despite great efforts invested over the past decade, their progress has been notably slower than expected. In this work, the facile solution synthesis of 2D PdAg alloy nanodendrites as a high-performance electrocatalyst is reported for ethanol electroxidation. The reaction is carried out via the coreduction of Pd and Ag precursors in aqueous solution with the presence of octadecyltrimethylammonium chloride as the structural directing agent. Final products feature small thickness (5–7 nm) and random in-plane branching with enlarged surface areas and abundant undercoordinated sites. They exhibit enhanced electrocatalytic activity (large specific current ≈2600 mA mgPd−1) and excellent operation stability (as revealed from both the cycling and chronoamperometric tests) for ethanol electroxidation. Control experiments show that the improvement comes from the combined electronic and structural effects.2D PdAg alloy nanodendrites are prepared in solution with assistance from a cationic surfactant with a long alkyl chain. They feature small thickness and random in-plane branching with enlarged surface areas and abundant undercoordinated sites. When evaluated as an electrocatalyst for the ethanol oxidation reaction, they demonstrate impressive electrocatalytic activity and stability superior to most other competitors.
      PubDate: 2018-01-16T09:26:27.679998-05:
      DOI: 10.1002/adma.201706962
  • 3D Printing of Materials with Tunable Failure via Bioinspired Mechanical
    • Authors: Dimitri Kokkinis; Florian Bouville, André R. Studart
      Abstract: Mechanical gradients are useful to reduce strain mismatches in heterogeneous materials and thus prevent premature failure of devices in a wide range of applications. While complex graded designs are a hallmark of biological materials, gradients in manmade materials are often limited to 1D profiles due to the lack of adequate fabrication tools. Here, a multimaterial 3D-printing platform is developed to fabricate elastomer gradients spanning three orders of magnitude in elastic modulus and used to investigate the role of various bioinspired gradient designs on the local and global mechanical behavior of synthetic materials. The digital image correlation data and finite element modeling indicate that gradients can be effectively used to manipulate the stress state and thus circumvent the weakening effect of defect-rich interfaces or program the failure behavior of heterogeneous materials. Implementing this concept in materials with bioinspired designs can potentially lead to defect-tolerant structures and to materials whose tunable failure facilitates repair of biomedical implants, stretchable electronics, or soft robotics.A gradient 3D-printing platform is developed and used to fabricate elastomer gradients with vastly different mechanical properties. It is used to investigate the role of bioinspired gradient designs on the mechanical behavior of heterogeneous materials. It is shown that bioinspired designs could potentially lead to more defect-tolerant soft structures and to materials whose tunable failure facilitates repair of biomedical implants, stretchable electronics, or soft robotics.
      PubDate: 2018-01-16T09:25:54.597717-05:
      DOI: 10.1002/adma.201705808
  • Ecologically Driven Ultrastructural and Hydrodynamic Designs in Stomatopod
    • Authors: Lessa Kay Grunenfelder; Garrett Milliron, Steven Herrera, Isaias Gallana, Nicholas Yaraghi, Nigel Hughes, Kenneth Evans-Lutterodt, Pablo Zavattieri, David Kisailus
      Abstract: Ecological pressures and varied feeding behaviors in a multitude of organisms have necessitated the drive for adaptation. One such change is seen in the feeding appendages of stomatopods, a group of highly predatory marine crustaceans. Stomatopods include “spearers,” who ambush and snare soft bodied prey, and “smashers,” who bludgeon hard-shelled prey with a heavily mineralized club. The regional substructural complexity of the stomatopod dactyl club from the smashing predator Odontodactylus scyllarus represents a model system in the study of impact tolerant biominerals. The club consists of a highly mineralized impact region, a characteristic Bouligand architecture (common to arthropods), and a unique section of the club, the striated region, composed of highly aligned sheets of mineralized fibers. Detailed ultrastructural investigations of the striated region within O. scyllarus and a related species of spearing stomatopod, Lysiosquillina maculate show consistent organization of mineral and organic, but distinct differences in macro-scale architecture. Evidence is provided for the function and substructural exaptation of the striated region, which facilitated redeployment of a raptorial feeding appendage as a biological hammer. Moreover, given the need to accelerate underwater and “grab” or “smash” their prey, the spearer and smasher appendages are specifically designed with a significantly reduced drag force.A highly aligned and mineralized structure is identified within the exocuticle of an impact-resistant crustacean appendage. This regional composite structure features circumferentially wrapped unidirectional chitinous fibers consisting of amorphous calcium carbonate and calcium phosphate that place the club under compression during high-energy strikes. Macro-morphological hydrodynamic features are revealed that significantly reduce drag, enabling acceleration to strike at incredibly high rates.
      PubDate: 2018-01-16T05:22:28.488664-05:
      DOI: 10.1002/adma.201705295
  • Slit Tubes for Semisoft Pneumatic Actuators
    • Authors: Lee Belding; Bilge Baytekin, Hasan Tarik Baytekin, Philipp Rothemund, Mohit S. Verma, Alex Nemiroski, Dan Sameoto, Bartosz A. Grzybowski, George M. Whitesides
      Abstract: This article describes a new principle for designing soft or ‘semisoft’ pneumatic actuators: SLiT (for SLit-in-Tube) actuators. Inflating an elastomeric balloon, when enclosed by an external shell (a material with higher Young's modulus) containing slits of different directions and lengths, produces a variety of motions, including bending, twisting, contraction, and elongation. The requisite pressure for actuation depends on the length of the slits, and this dependence allows sequential actuation by controlling the applied pressure. Different actuators can also be controlled using external “sliders” that act as reprogrammable “on-off” switches. A pneumatic arm and a walker constructed from SLiT actuators demonstrate their ease of fabrication and the range of motions they can achieve.A new class of semisoft pneumatic actuators, which can achieve a range of complex motions, is presented. The arrangement of slits into an external, thin-walled and inextensible shell (which constrains the inflation of a silicone tube) controls the motions of soft pneumatic actuators. This design enables the fabrication of a pneumatically actuated arm and a walker.
      PubDate: 2018-01-15T06:12:28.275968-05:
      DOI: 10.1002/adma.201704446
  • Crystallization: A Novel Acoustomicrofluidic Nebulization Technique
           Yielding New Crystallization Morphologies (Adv. Mater. 3/2018)
    • Authors: Heba Ahmed; Lillian Lee, Connie Darmanin, Leslie Y. Yeo
      Abstract: New crystal morphologies, previously undiscovered, for both organic and inorganic materials are obtained by Leslie Y. Yeo and co-workers, as discussed in article number 1602040, as a consequence of the unique intermediate evaporation rate regime to which aerosol droplets, generated from a microfluidic nebulization platform utilizing a recently discovered novel class of hybrid surface and bulk acoustic waves, are subjected.
      PubDate: 2018-01-15T05:54:52.960781-05:
      DOI: 10.1002/adma.201870018
  • Drug Delivery: Dimeric Drug Polymeric Micelles with Acid-Active Tumor
           Targeting and FRET-Traceable Drug Release (Adv. Mater. 3/2018)
    • Authors: Xing Guo; Lin Wang, Kayla Duval, Jing Fan, Shaobing Zhou, Zi Chen
      Abstract: In article number 1705436, Shaobing Zhou, Zi Chen, and co-workers develop an acid-active tumor-targeting nanoplatform with self-reported drug-release capability. This platform has unique features, such as a long blood circulation through shielding of the cationic charges of trans-activating transcriptional activator (TAT), an enhanced cellular internalization by regenerating the original TAT in acidic tumor tissue, and a self-reported drug release via the Förster resonance energy transfer (FRET) signal triggered by the intracellular reductant.
      PubDate: 2018-01-15T05:54:52.103617-05:
      DOI: 10.1002/adma.201870020
  • Photothermal CO2 Hydrogenation: Alumina-Supported CoFe Alloy Catalysts
           Derived from Layered-Double-Hydroxide Nanosheets for Efficient
           Photothermal CO2 Hydrogenation to Hydrocarbons (Adv. Mater. 3/2018)
    • Authors: Guangbo Chen; Rui Gao, Yufei Zhao, Zhenhua Li, Geoffrey I. N. Waterhouse, Run Shi, Jiaqing Zhao, Mengtao Zhang, Lu Shang, Guiyang Sheng, Xiangping Zhang, Xiaodong Wen, Li-Zhu Wu, Chen-Ho Tung, Tierui Zhang
      Abstract: In article number 1704663, Tierui Zhang and co-workers report alumina-supported CoFe-alloy catalysts fabricated by hydrogen reduction of CoFeAl layereddouble-hydroxide nanosheets, exhibiting remarkable performance for photothermal CO2 hydrogenation to valuable hydrocarbons. This result demonstrates a completely new approach for harnessing abundant solar energy to produce high-value hydrocarbons from a CO2 feedstock.
      PubDate: 2018-01-15T05:54:50.14043-05:0
      DOI: 10.1002/adma.201870015
  • Nanofluidics: Nanofluidics: A New Arena for Materials Science (Adv. Mater.
    • Authors: Yan Xu
      Abstract: The use of nanofluidics opens up a new arena for materials science. Especially, it offers the possibility of selective manipulation and accurate assembly of individual molecules and nanoscale objects in the liquid phase, revolutionarily impacting on future material fabrication and chemical synthesis. Burgeoning progress has been made, and some of this progress, of particular interest, is discussed by Yan Xu in article number 1702419.
      PubDate: 2018-01-15T05:54:46.468632-05:
      DOI: 10.1002/adma.201870019
  • Masthead: (Adv. Mater. 3/2018)
    • PubDate: 2018-01-15T05:54:46.387493-05:
      DOI: 10.1002/adma.201870017
  • Nanopatterning: A 3D Self-Shaping Strategy for Nanoresolution
           Multicomponent Architectures (Adv. Mater. 3/2018)
    • Authors: Meng Su; Zhandong Huang, Yifan Li, Xin Qian, Zheng Li, Xiaotian Hu, Qi Pan, Fengyu Li, Lihong Li, Yanlin Song
      Abstract: A 3D self-shaping strategy is developed by Fengyu Li, Yanlin Song, and co-workers in article number 1703963 to fabricate nanoresolution multicomponent 3D architectures. The as-prepared 3D circuits assembled by silver nanoparticles carry a current of 208–448 μA at an impressed voltage of 0.01 V, while the 3D architectures achieved by two different quantum dots show non-interfering optical properties with feature resolution below 3 μm. The new strategy for fabrication of micro–nano geometric patterns without a modeling program will promote the development of functional 3D devices.
      PubDate: 2018-01-15T05:54:43.581013-05:
      DOI: 10.1002/adma.201870014
  • Contents: (Adv. Mater. 3/2018)
    • PubDate: 2018-01-15T05:54:42.831603-05:
      DOI: 10.1002/adma.201870016
  • Hierarchical Porous Nanosheets Constructed by Graphene-Coated,
           Interconnected TiO2 Nanoparticles for Ultrafast Sodium Storage
    • Authors: Baosong Li; Baojuan Xi, Zhenyu Feng, Yue Lin, Jincheng Liu, Jinkui Feng, Yitai Qian, Shenglin Xiong
      Abstract: Sodium-ion batteries (SIBs) are considered promising next-generation energy storage devices. However, a lack of appropriate high-performance anode materials has prevented further improvements. Here, a hierarchical porous hybrid nanosheet composed of interconnected uniform TiO2 nanoparticles and nitrogen-doped graphene layer networks (TiO2@NFG HPHNSs) that are synthesized using dual-functional C3N4 nanosheets as both the self-sacrificing template and hybrid carbon source is reported. These HPHNSs deliver high reversible capacities of 146 mA h g−1 at 5 C for 8000 cycles, 129 mA h g−1 at 10 C for 20 000 cycles, and 116 mA h g−1 at 20 C for 10 000 cycles, as well as an ultrahigh rate capability up to 60 C with a capacity of 101 mA h g−1. These results demonstrate the longest cyclabilities and best rate capability ever reported for TiO2-based anode materials for SIBs. The unprecedented sodium storage performance of the TiO2@NFG HPHNSs is due to their unique composition and hierarchical porous 2D structure.The first synthesis of novel nitrogen-doped few-layered graphene-wrapped TiO2 ­hierarchical porous hybrid ­nanosheets using dual-functional C3N4 sheets as both the sacrificial template and hybrid carbon source results in a high reversible ­capacity, unprecedented cycling ­stability, and excellent rate capability as anode materials for sodium-ion batteries due to their unique composition and ­hierarchical porous 2D structure.
      PubDate: 2018-01-15T05:15:22.464298-05:
      DOI: 10.1002/adma.201705788
  • Colloidal Cobalt Phosphide Nanocrystals as Trifunctional Electrocatalysts
           for Overall Water Splitting Powered by a Zinc–Air Battery
    • Authors: Hui Li; Qi Li, Peng Wen, Trey B. Williams, Shiba Adhikari, Chaochao Dun, Chang Lu, Dominique Itanze, Lin Jiang, David L. Carroll, George L. Donati, Pamela M. Lundin, Yejun Qiu, Scott M. Geyer
      Abstract: Highly efficient and stable electrocatalysts, particularly those that are capable of multifunctionality in the same electrolyte, are in high demand for the hydrogen evolution reaction (HER), oxygen evolution reaction (OER), and oxygen reduction reaction (ORR). In this work, highly monodisperse CoP and Co2P nanocrystals (NCs) are synthesized using a robust solution-phase method. The highly exposed (211) crystal plane and abundant surface phosphide atoms make the CoP NCs efficient catalysts toward ORR and HER, while metal-rich Co2P NCs show higher OER performance owing to easier formation of plentiful Co2P@COOH heterojunctions. Density functional theory calculation results indicate that the desorption of OH* from cobalt sites is the rate-limiting step for both CoP and Co2P in ORR and that the high content of phosphide can lower the reaction barrier. A water electrolyzer constructed with a CoP NC cathode and a Co2P NC anode can achieve a current density of 10 mA cm−2 at 1.56 V, comparable even to the noble metal-based Pt/C and RuO2/C pair. Furthermore, the CoP NCs are employed as an air cathode in a primary zinc–air battery, exhibiting a high power density of 62 mW cm−2 and good stability.Monodisperse cobalt phosphide (CoP and Co2P) nanocrystals are used as trifunctional catalysts toward oxygen reduction, hydrogen evolution, and oxygen evolution in alkaline electrolyte. A full alkaline electrolyzer composed of a CoP cathode and Co2P anode can achieve 10 mA cm2 at a voltage of 1.56 V for overall water splitting, which rivals the integrated state-of-the-art Pt/C and RuO2/C.
      PubDate: 2018-01-15T05:09:16.230056-05:
      DOI: 10.1002/adma.201705796
  • Liquid Letters
    • Authors: Shaowei Shi; Xubo Liu, Yanan Li, Xuefei Wu, Dong Wang, Joe Forth, Thomas P. Russell
      Abstract: Using the interfacial jamming of cellulose nanocrystal (CNC) surfactants, a new concept, termed all-liquid molding, is introduced to produce all-liquid objects that retain the shape and details of the mold with high fidelity, yet remain all liquid and are responsive to external stimuli. This simple process, where the viscosity of the CNC dispersion can range from that of water to a crosslinked gel, opens tremendous opportunities for encapsulation, delivery systems, and unique microfluidic devices. The process described is generally applicable to any functionalized nanoparticles dispersed in one liquid and polymer ligands having complementary functionality dissolved in a second immiscible liquid. Such sculpted liquids retain all the characteristics of the liquids but retain shape indefinitely, very much like a solid, and provide a new platform for next-generation soft materials.Using the interfacial jamming of cellulose nanocrystal surfactants, a concept, termed all-liquid molding,is introduced to produce all-liquid objects that retain the shape and details of the mold with high fidelity. The process is generally applicable to any functionalized nanoparticles dispersed in one liquid and polymer ligands having complementary functionality dissolved in a second immiscible liquid, providing a new platform for next-generation soft materials.
      PubDate: 2018-01-15T05:08:50.669113-05:
      DOI: 10.1002/adma.201705800
  • Digitalizing Self-Assembled Chiral Superstructures for Optical Vortex
    • Authors: Peng Chen; Ling-Ling Ma, Wei Duan, Ji Chen, Shi-Jun Ge, Zhi-Han Zhu, Ming-Jie Tang, Ran Xu, Wei Gao, Tao Li, Wei Hu, Yan-Qing Lu
      Abstract: Cholesteric liquid crystal (CLC) chiral superstructures exhibit unique features; that is, polychromatic and spin-determined phase modulation. Here, a concept for digitalized chiral superstructures is proposed, which further enables the arbitrary manipulation of reflective geometric phase and may significantly upgrade existing optical apparatus. By encoding a specifically designed binary pattern, an innovative CLC optical vortex (OV) processor is demonstrated. Up to 25 different OVs are extracted with equal efficiency over a wavelength range of 116 nm. The multiplexed OVs can be detected simultaneously without mode crosstalk or distortion, permitting a polychromatic, large-capacity, and in situ method for parallel OV processing. Such complex but easily fabricated self-assembled chiral superstructures exhibit versatile functionalities, and provide a satisfactory platform for OV manipulation and other cutting-edge territories. This work is a vital step towards extending the fundamental understanding and fantastic applications of ordered soft matter.Digitalized chiral superstructures enable the generation, detection, and demultiplexing of optical vortices in a polychromatic, large-capacity, and in situ way. Such complex but easily fabricated self-assembled cholesteric liquid crystal superstructures provide a versatile platform for various cutting-edge territories. This work brings new insights to both fundamental understanding and innovative applications of ordered soft matter.
      PubDate: 2018-01-15T05:08:02.180328-05:
      DOI: 10.1002/adma.201705865
  • Self-Powered Si/CdS Flexible Photodetector with Broadband Response from
           325 to 1550 nm Based on Pyro-phototronic Effect: An Approach for
           Photosensing below Bandgap Energy
    • Authors: Yejing Dai; Xingfu Wang, Wenbo Peng, Cheng Xu, Changsheng Wu, Kai Dong, Ruiyuan Liu, Zhong Lin Wang
      Abstract: Cadmium sulfide (CdS) has received widespread attention as the building block of optoelectronic devices due to its extraordinary optoelectronic properties, low work function, and excellent thermal and chemical stability. Here, a self-powered flexible photodetector (PD) based on p-Si/n-CdS nanowires heterostructure is fabricated. By introducing the pyro-phototronic effect derived from wurtzite structured CdS, the self-powered PD shows a broadband response range, even beyond the bandgap limitation, from UV (325 nm) to near infrared (1550 nm) under zero bias with fast response speed. The light-induced pyroelectric potential is utilized to modulate the optoelectronic processes and thus improve the photoresponse performance. Lasers with different wavelengths have different effects on the self-powered PDs and corresponding working mechanisms are carefully investigated. Upon 325 nm laser illumination, the rise time and fall time of the self-powered PD are 245 and 277 µs, respectively, which are faster than those of most previously reported CdS-based nanostructure PDs. Meanwhile, the photoresponsivity R and specific detectivity D* regarding to the relative peak-to-peak current are both enhanced by 67.8 times, compared with those only based on the photovoltaic effect-induced photocurrent. The self-powered flexible PD with fast speed, stable, and broadband response is expected to have extensive applications in various environments.By utilizing the pyro-phototronic effect, the self-powered CdS/Si flexible photodetector shows a broadband response range from UV (325 nm) to near infrared (1550 nm) under zero bias with fast response speed, which is even beyond the limitation of the intrinsic bandgap. The photoresponse performance of the self-powered PD is greatly improved in a broadband range by introducing the pyro-phototronic effect.
      PubDate: 2018-01-15T05:07:27.657309-05:
      DOI: 10.1002/adma.201705893
  • Fused Tris(thienothiophene)-Based Electron Acceptor with Strong
           Near-Infrared Absorption for High-Performance As-Cast Solar Cells
    • Authors: Tengfei Li; Shuixing Dai, Zhifan Ke, Langxuan Yang, Jiayu Wang, Cenqi Yan, Wei Ma, Xiaowei Zhan
      Abstract: A fused tris(thienothiophene) (3TT) building block is designed and synthesized with strong electron-donating and molecular packing properties, where three thienothiophene units are condensed with two cyclopentadienyl rings. Based on 3TT, a fused octacylic electron acceptor (FOIC) is designed and synthesized, using strong electron-withdrawing 2-(5/6-fluoro-3-oxo-2,3-dihydro-1H-inden-1-ylidene)-malononitrile as end groups. FOIC exhibits absorption in 600–950 nm region peaked at 836 nm with extinction coefficient of up to 2 × 105m–1 cm–1, low bandgap of 1.32 eV, and high electron mobility of 1.2 × 10–3 cm2 V–1 s–1. Compared with its counterpart ITIC3 based on indacenothienothiophene core, FOIC exhibits significantly upshifted highest occupied molecular orbital level, slightly downshifted lowest unoccupied molecular orbital level, significantly redshifted absorption, and higher mobility. The as-cast organic solar cells (OSCs) based on blends of PTB7-Th donor and FOIC acceptor without additional treatments exhibit power conversion efficiencies (PCEs) as high as 12.0%, which is much higher than that of PTB7-Th: ITIC3 (8.09%). The as-cast semitransparent OSCs based on the same blends show PCEs of up to 10.3% with an average visible transmittance of 37.4%.A fused tris(thienothiophene)-based electron acceptor with strong near-infrared absorption and high electron mobility is designed, synthesized, and applied in as-cast organic solar cells and as-cast semitransparent organic solar cells, which exhibit efficiencies of 12.0% and 10.3%, respectively.
      PubDate: 2018-01-15T05:06:54.696768-05:
      DOI: 10.1002/adma.201705969
  • 3D Printing of Liquid Crystal Elastomeric Actuators with Spatially
           Programed Nematic Order
    • Authors: Arda Kotikian; Ryan L. Truby, John William Boley, Timothy J. White, Jennifer A. Lewis
      Abstract: Liquid crystal elastomers (LCEs) are soft materials capable of large, reversible shape changes, which may find potential application as artificial muscles, soft robots, and dynamic functional architectures. Here, the design and additive manufacturing of LCE actuators (LCEAs) with spatially programed nematic order that exhibit large, reversible, and repeatable contraction with high specific work capacity are reported. First, a photopolymerizable, solvent-free, main-chain LCE ink is created via aza-Michael addition with the appropriate viscoelastic properties for 3D printing. Next, high operating temperature direct ink writing of LCE inks is used to align their mesogen domains along the direction of the print path. To demonstrate the power of this additive manufacturing approach, shape-morphing LCEA architectures are fabricated, which undergo reversible planar-to-3D and 3D-to-3D′ transformations on demand, that can lift significantly more weight than other LCEAs reported to date.3D liquid crystal elastomer actuators with programed director alignment are designed and fabricated via high operating temperature direct ink writing. The additive manufacturing method produces dynamic shape-morphing architectures in arbitrary form factors that are capable of lifting heavy loads.
      PubDate: 2018-01-15T05:06:40.108219-05:
      DOI: 10.1002/adma.201706164
  • Fine-Tuning of Molecular Packing and Energy Level through Methyl
           Substitution Enabling Excellent Small Molecule Acceptors for Nonfullerene
           Polymer Solar Cells with Efficiency up to 12.54%
    • Authors: Zhenghui Luo; Haijun Bin, Tao Liu, Zhi-Guo Zhang, Yankang Yang, Cheng Zhong, Beibei Qiu, Guanghao Li, Wei Gao, Dongjun Xie, Kailong Wu, Yanming Sun, Feng Liu, Yongfang Li, Chuluo Yang
      Abstract: A novel small molecule acceptor MeIC with a methylated end-capping group is developed. Compared to unmethylated counterparts (ITCPTC), MeIC exhibits a higher lowest unoccupied molecular orbital (LUMO) level value, tighter molecular packing, better crystallites quality, and stronger absorption in the range of 520–740 nm. The MeIC-based polymer solar cells (PSCs) with J71 as donor, achieve high power conversion efficiency (PCE), up to 12.54% with a short-circuit current (JSC) of 18.41 mA cm−2, significantly higher than that of the device based on J71:ITCPTC (11.63% with a JSC of 17.52 mA cm−2). The higher JSC of the PSC based on J71:MeIC can be attributed to more balanced μh/μe, higher charge dissociation and charge collection efficiency, better molecular packing, and more proper phase separation features as indicated by grazing incident X-ray diffraction and resonant soft X-ray scattering results. It is worth mentioning that the as-cast PSCs based on MeIC also yield a high PCE of 11.26%, which is among the highest value for the as-cast nonfullerene PSCs so far. Such a small modification that leads to so significant an improvement of the photovoltaic performance is a quite exciting finding, shining a light on the molecular design of the nonfullerene acceptors.A novel small molecule acceptor MeIC with a methylated end-capping group is developed. Compared to unmethylated counterparts (ITCPTC), MeIC exhibits higher LUMO level, tighter molecular packing, and better crystallites quality. The MeIC-based polymer solar cells with J71 as donor achieved high power conversion efficiency up to 12.54%, significantly higher than that of the device of ITCPTC.
      PubDate: 2018-01-15T05:05:13.648022-05:
      DOI: 10.1002/adma.201706124
  • A General Method for the Chemical Synthesis of Large-Scale, Seamless
           Transition Metal Dichalcogenide Electronics
    • Authors: Li Li; Yichuan Guo, Yuping Sun, Long Yang, Liang Qin, Shouliang Guan, Jinfen Wang, Xiaohui Qiu, Hongbian Li, Yuanyuan Shang, Ying Fang
      Abstract: The capability to directly build atomically thin transition metal dichalcogenide (TMD) devices by chemical synthesis offers important opportunities to achieve large-scale electronics and optoelectronics with seamless interfaces. Here, a general approach for the chemical synthesis of a variety of TMD (e.g., MoS2, WS2, and MoSe2) device arrays over large areas is reported. During chemical vapor deposition, semiconducting TMD channels and metallic TMD/carbon nanotube (CNT) hybrid electrodes are simultaneously formed on CNT-patterned substrate, and then coalesce into seamless devices. Chemically synthesized TMD devices exhibit attractive electrical and mechanical properties. It is demonstrated that chemically synthesized MoS2–MoS2/CNT devices have Ohmic contacts between MoS2/CNT hybrid electrodes and MoS2 channels. In addition, MoS2–MoS2/CNT devices show greatly enhanced mechanical stability and photoresponsivity compared with conventional gold-contacted devices, which makes them suitable for flexible optoelectronics. Accordingly, a highly flexible pixel array based on chemically synthesized MoS2–MoS2/CNT photodetectors is applied for image sensing.Seamless and large-area transition metal dichalcogenide (TMD) electronics with semiconducting TMD channels and TMD/CNT hybrid electrodes are synthesized by chemical vapor deposition. Ohmic contacts are formed between MoS2/CNT hybrid electrodes and MoS2 channels. In addition, MoS2–MoS2/CNT devices show enhanced mechanical stability and photoresponsivity compared with metal-contacted devices, which makes them suitable for flexible optoelectronics.
      PubDate: 2018-01-15T05:04:56.367853-05:
      DOI: 10.1002/adma.201706215
  • Uniform Lithium Nucleation/Growth Induced by Lightweight Nitrogen-Doped
           Graphitic Carbon Foams for High-Performance Lithium Metal Anodes
    • Authors: Lin Liu; Ya-Xia Yin, Jin-Yi Li, Shu-Hua Wang, Yu-Guo Guo, Li-Jun Wan
      Abstract: The lithium metal anode has attracted soaring attention as an ideal battery anode. Unfortunately, nonuniform Li nucleation results in uncontrollable growth of dendritic Li, which incurs serious safety issues and poor electrochemical performance, hindering its practical applications. Herein, this study shows that uniform Li nucleation/growth can be induced by an ultralight 3D current collector consisting of in situ nitrogen-doped graphitic carbon foams (NGCFs) to realize suppressing dendritic Li growth at the nucleating stage. The N-containing functional groups guide homogenous growth of Li nucleus nanoparticles and the initial Li nucleus seed layer regulates the following well-distributed Li growth. Benefiting from such favorable Li growth behavior, superior electrochemical performance can be achieved as evidenced by the high Coulombic efficiency (≈99.6% for 300 cycles), large capacity (10 mA h cm−2, 3140 mA h g−1NGCF-Li), and ultralong lifespan (>1200 h) together with low overpotential (
      PubDate: 2018-01-15T05:04:29.399511-05:
      DOI: 10.1002/adma.201706216
  • Self-Assembled Ag-MXA Superclusters with Structure-Dependent Mechanical
    • Authors: Xiaoyun Qin; Dan Luo, Zhenjie Xue, Qian Song, Tie Wang
      Abstract: The low elastic modulus and time-consuming formation process represent the major challenges that impede the penetration of nanoparticle superstructures into daily life applications. As observed in the molecular or atomic crystals, more effective interactions between adjacent nanoparticles would introduce beneficial features to assemblies enabling optimized mechanical properties. Here, a straightforward synthetic strategy is showed that allows fast and scalable fabrication of 2D Ag-mercaptoalkyl acid superclusters of either hexagonal or lamellar topology. Remarkably, these ordered superstructures exhibit a structure-dependent elastic modulus which is subject to the tether length of straight-chain mercaptoalkyl acids or the ratio between silver and tether molecules. These superclusters are plastic and moldable against arbitrarily shaped masters of macroscopic dimensions, thereby opening a wealth of possibilities to develop more nanocrystals with practically useful nanoscopic properties.The Ag-mercaptoalkyl acid superclusters with different architectures exhibit structure-dependent mechanical properties. Inspired by molecular or atomic crystal, whose mechanical properties are dramatically different between various packing modes, the nanoparticle assemblies' mechanical properties can be tuned by controlling the crystal structure. Assembly of hexagonal, lamellar, and random structures of superclusters through hydrogen bonds between the tether molecules is reported.
      PubDate: 2018-01-15T05:03:59.486549-05:
      DOI: 10.1002/adma.201706327
  • Nano Titanium Monoxide Crystals and Unusual Superconductivity at 11 K
    • Authors: Jijian Xu; Dong Wang, Heliang Yao, Kejun Bu, Jie Pan, Jianqiao He, Fangfang Xu, Zhanglian Hong, Xiaobo Chen, Fuqiang Huang
      Abstract: Nano TiO2 is investigated intensely due to extraordinary photoelectric performances in photocatalysis, new-type solar cells, etc., but only very few synthesis and physical properties have been reported on nanostructured TiO or other low valent titanium-containing oxides. Here, a core–shell nanoparticle made of TiO core covered with a ≈5 nm shell of amorphous TiO1+x is newly constructed via a controllable reduction method to synthesize nano TiO core and subsequent soft oxidation to form the shell (TiO1+x). The physical properties measurements of electrical transport and magnetism indicate these TiO@TiO1+x nanocrystals are a type-ІІ superconductor of a recorded Tconset = 11 K in the binary Ti–O system. This unusual superconductivity could be attributed to the interfacial effect due to the nearly linear gradient of O/Ti ratio across the outer amorphous layer. This novel synthetic method and enhanced superconductivity could open up possibilities in interface superconductivity of nanostructured composites with well-controlled interfaces.Nano titanium monoxide with the crystalline core (TiO) covered with a ≈5 nm shell of amorphous TiO1+x is the first time to be prepared and the highest Tc (11 K) in the binary Ti–O system is observed. Through controllable reduction and soft oxidation, the obtained sample is observed with nearly linear (1.0–1.9) variation of O/Ti ratio across the amorphous layer, suggesting a smooth interface which contributes to the unusual superconductivity.
      PubDate: 2018-01-15T05:03:27.488588-05:
      DOI: 10.1002/adma.201706240
  • Dynamic Coordination of Eu–Iminodiacetate to Control Fluorochromic
           Response of Polymer Hydrogels to Multistimuli
    • Authors: Gengsheng Weng; Srinivas Thanneeru, Jie He
      Abstract: New fluorochromic materials that reversibly change their emission properties in response to their environment are of interest for the development of sensors and light-emitting materials. A new design of Eu-containing polymer hydrogels showing fast self-healing and tunable fluorochromic properties in response to five different stimuli, including pH, temperature, metal ions, sonication, and force, is reported. The polymer hydrogels are fabricated using Eu–iminodiacetate (IDA) coordination in a hydrophilic poly(N,N-dimethylacrylamide) matrix. Dynamic metal–ligand coordination allows reversible formation and disruption of hydrogel networks under various stimuli which makes hydrogels self-healable and injectable. Such hydrogels show interesting switchable ON/OFF luminescence along with the sol–gel transition through the reversible formation and dissociation of Eu–IDA complexes upon various stimuli. It is demonstrated that Eu-containing hydrogels display fast and reversible mechanochromic response as well in hydrogels having interpenetrating polymer network. Those multistimuli responsive fluorochromic hydrogels illustrate a new pathway to make smart optical materials, particularly for biological sensors where multistimuli response is required.A new design of Eu-containing polymer hydrogels showing fast self-healing and interesting switchable ON/OFF luminescence along with the sol–gel transition upon five different stimuli is reported.
      PubDate: 2018-01-15T05:03:11.965601-05:
      DOI: 10.1002/adma.201706526
  • Cellulose-Based Biomimetics and Their Applications
    • Authors: Ana P. C. Almeida; João P. Canejo, Susete N. Fernandes, Coro Echeverria, Pedro L. Almeida, Maria H. Godinho
      Abstract: Nature has been producing cellulose since long before man walked the surface of the earth. Millions of years of natural design and testing have resulted in cellulose-based structures that are an inspiration for the production of synthetic materials based on cellulose with properties that can mimic natural designs, functions, and properties. Here, five sections describe cellulose-based materials with characteristics that are inspired by gratings that exist on the petals of the plants, structurally colored materials, helical filaments produced by plants, water-responsive materials in plants, and environmental stimuli-responsive tissues found in insects and plants. The synthetic cellulose-based materials described herein are in the form of fibers and films. Fascinating multifunctional materials are prepared from cellulose-based liquid crystals and from composite cellulosic materials that combine functionality with structural performance. Future and recent applications are outlined.Cellulose and cellulose-based materials with properties that mimic natural designs and functions inspired by gratings, helical filaments, structurally colored water, and stimuli-responsive materials that exist in insects and plants are reviewed. The synthetic cellulose-based materials described are in the form of fibers and films. Future and recent applications are outlined.
      PubDate: 2018-01-15T04:48:06.341515-05:
      DOI: 10.1002/adma.201703655
  • Mobility Engineering in Vertical Field Effect Transistors Based on Van der
           Waals Heterostructures
    • Authors: Yong Seon Shin; Kiyoung Lee, Young Rae Kim, Hyangsook Lee, I. Min Lee, Won Tae Kang, Boo Heung Lee, Kunnyun Kim, Jinseong Heo, Seongjun Park, Young Hee Lee, Woo Jong Yu
      Abstract: Vertical integration of 2D layered materials to form van der Waals heterostructures (vdWHs) offers new functional electronic and optoelectronic devices. However, the mobility in vertical carrier transport in vdWHs of vertical field-effect transistor (VFET) is not yet investigated in spite of the importance of mobility for the successful application of VFETs in integrated circuits. Here, the mobility in VFET of vdWHs under different drain biases, gate biases, and metal work functions is first investigated and engineered. The traps in WSe2 are the main source of scattering, which influences the vertical mobility and three distinct transport mechanisms: Ohmic transport, trap-limited transport, and space-charge-limited transport. The vertical mobility in VFET can be improved by suppressing the trap states by raising the Fermi level of WSe2. This is achieved by increasing the injected carrier density by applying a high drain voltage, or decreasing the Schottky barrier at the graphene/WSe2 and metal/WSe2 junctions by applying a gate bias and reducing the metal work function, respectively. Consequently, the mobility in Mn vdWH at +50 V gate voltage is about 76 times higher than the initial mobility of Au vdWH. This work enables further improvements in the VFET for successful application in integrated circuits.The mobility in vertical carrier transport of vertical field-effect transistors (VFETs) composed of 2D layered materials has not previously been investigated in spite of the importance of the mobility for the successful application of VFETs in integrated circuits. The mobility in VFETs of van der Waals heterostructures under different drain biases, gate biases, and metal work functions is investigated and engineerd.
      PubDate: 2018-01-15T04:46:05.738531-05:
      DOI: 10.1002/adma.201704435
  • Hot-Electron-Assisted Femtosecond All-Optical Modulation in Plasmonics
    • Authors: Mohammad Taghinejad; Hossein Taghinejad, Zihao Xu, Yawei Liu, Sean P. Rodrigues, Kyu-Tae Lee, Tianquan Lian, Ali Adibi, Wenshan Cai
      Abstract: The optical Kerr nonlinearity of plasmonic metals provides enticing prospects for developing reconfigurable and ultracompact all-optical modulators. In nanostructured metals, the coherent coupling of light energy to plasmon resonances creates a nonequilibrium electron distribution at an elevated electron temperature that gives rise to significant Kerr optical nonlinearities. Although enhanced nonlinear responses of metals facilitate the realization of efficient modulation devices, the intrinsically slow relaxation dynamics of the photoexcited carriers, primarily governed by electron–phonon interactions, impedes ultrafast all-optical modulation. Here, femtosecond (≈190 fs) all-optical modulation in plasmonic systems via the activation of relaxation pathways for hot electrons at the interface of metals and electron acceptor materials, following an on-resonance excitation of subradiant lattice plasmon modes, is demonstrated. Both the relaxation kinetics and the optical nonlinearity can be actively tuned by leveraging the spectral response of the plasmonic design in the linear regime. The findings offer an opportunity to exploit hot-electron-induced nonlinearities for design of self-contained, ultrafast, and low-power all-optical modulators based on plasmonic platforms.Exchange of hot electrons at the interface of plasmonic metals and electron acceptor materials is employed to enable an electron-dominated relaxation pathway for demonstration of femtosecond (≈190 fs) all-optical modulation in plasmonic systems. Relaxation dynamics and optical nonlinearity are actively tuned by leveraging the linear spectral response of a designed plasmonic lattice suitable for all-optical data processing.
      PubDate: 2018-01-15T04:45:39.252123-05:
      DOI: 10.1002/adma.201704915
  • Surface Engineering for Extremely Enhanced Charge Separation and
           Photocatalytic Hydrogen Evolution on g-C3N4
    • Authors: Yu Yu; Wei Yan, Xiaofang Wang, Pei Li, Wenyu Gao, Haihan Zou, Songmei Wu, Kejian Ding
      Abstract: Reinforcing the carrier separation is the key issue to maximize the photocatalytic hydrogen evolution (PHE) efficiency of graphitic carbon nitride (g-C3N4). By a surface engineering of gradual doping of graphited carbon rings within g-C3N4, suitable energy band structures and built-in electric fields are established. Photoinduced electrons and holes are impelled into diverse directions, leading to a 21-fold improvement in the PHE rate.A facial surface engineering strategy of gradual doping of Cgra rings at different depths to surface in g-C3N4 is presented. Suitable energy band layouts and built-in electric fields drastically accelerate carrier separation by impelling photoinduced electrons and holes into diverse directions, and hence elevate the photocatalytic hydrogen evolution rate by 21-fold.
      PubDate: 2018-01-15T04:45:18.23197-05:0
      DOI: 10.1002/adma.201705060
  • Co(OH)2 Nanoparticle-Encapsulating Conductive Nanowires Array:
           Room-Temperature Electrochemical Preparation for High-Performance Water
           Oxidation Electrocatalysis
    • Authors: Dan Wu; Yicheng Wei, Xiang Ren, Xuqiang Ji, Yiwei Liu, Xiaodong Guo, Zhiang Liu, Abdullah M. Asiri, Qin Wei, Xuping Sun
      Abstract: It is highly desired but still remains challenging to design and develop a Co-based nanoparticle-encapsulated conductive nanoarray at room temperature for high-performance water oxidation electrocatalysis. Here, it is reported that room-temperature anodization of a Co(TCNQ)2 (TCNQ = tetracyanoquinodimethane) nanowire array on copper foam at alkaline pH leads to in situ electrochemcial oxidation of TCNQ− into water-insoluable TCNQ nanoarray embedding Co(OH)2 nanoparticles. Such Co(OH)2-TCNQ/CF shows superior catalytic activity for water oxidation and demands only a low overpotential of 276 mV to drive a geometrical current density of 25 mA cm−2 in 1.0 m KOH. Notably, it also demonstrates strong long-term electrochemical durability with its activity being retrained for at least 25 h, a high turnover frequency of 0.97 s−1 at an overpotential of 450 mV and 100% Faradic efficiency. This study provides an exciting new method for the rational design and development of a conductive TCNQ-based nanoarray as an interesting 3D material for advanced electrochemical applications.A Co(OH)2 nanoparticle-encapsulating conductive tetracyanoquinodimethane (TCNQ) nanowire array on copper foam is prepared using an in situ electrochemical oxidation method to form a water-insoluable conductive TCNQ nanoarray. This array effectively entraps Co(OH)2 nanoparticles at alkaline pH. Such Co(OH)2-TCNQ/CF requires an overpotential as low as 276 mV to drive a geometrical current density of 25 mA cm−2 in 1.0 M KOH, with strong long-term electrochemical durability.
      PubDate: 2018-01-15T04:44:50.526707-05:
      DOI: 10.1002/adma.201705366
  • Polymer-Passivated Inorganic Cesium Lead Mixed-Halide Perovskites for
           Stable and Efficient Solar Cells with High Open-Circuit Voltage over 1.3 V
    • Authors: Qingsen Zeng; Xiaoyu Zhang, Xiaolei Feng, Siyu Lu, Zhaolai Chen, Xue Yong, Simon A. T. Redfern, Haotong Wei, Haiyu Wang, Huaizhong Shen, Wei Zhang, Weitao Zheng, Hao Zhang, John S. Tse, Bai Yang
      Abstract: Cesium-based trihalide perovskites have been demonstrated as promising light absorbers for photovoltaic applications due to their superb composition stability. However, the large energy losses (Eloss) observed in inorganic perovskite solar cells has become a major hindrance impairing the ultimate efficiency. Here, an effective and reproducible method of modifying the interface between a CsPbI2Br absorber and polythiophene hole-acceptor to minimize the Eloss is reported. It is demonstrated that polythiophene, deposited on the top of CsPbI2Br, can significantly reduce electron-hole recombination within the perovskite, which is due to the electronic passivation of surface defect states. In addition, the interfacial properties are improved by a simple annealing process, leading to significantly reduced energy disorder in polythiophene and enhanced hole-injection into the hole-acceptor. Consequently, one of the highest power conversion efficiency (PCE) of 12.02% from a reverse scan in inorganic mixed-halide perovskite solar cells is obtained. Modifying the perovskite films with annealing polythiophene enables an open-circuit voltage (VOC) of up to 1.32 V and Eloss of down to 0.5 eV, which both are the optimal values reported among cesium-lead mixed-halide perovskite solar cells to date. This method provides a new route to further improve the efficiency of perovskite solar cells by minimizing the Eloss.The interfacial properties between CsPbI2Br absorber and poly(3-hexylthiophene) (P3HT) hole-acceptor are improved by passivating the surface defects of CsPbI2Br and reducing the energy disorder of P3HT. Consequently, a stable inorganic perovskite solar cell with high power conversion efficiency of 12.02% and minimal energy loss of 0.50 eV is obtained.
      PubDate: 2018-01-15T04:44:25.019047-05:
      DOI: 10.1002/adma.201705393
  • Preparation of High-Percentage 1T-Phase Transition Metal Dichalcogenide
           Nanodots for Electrochemical Hydrogen Evolution
    • Authors: Chaoliang Tan; Zhimin Luo, Apoorva Chaturvedi, Yongqing Cai, Yonghua Du, Yue Gong, Ying Huang, Zhuangchai Lai, Xiao Zhang, Lirong Zheng, Xiaoying Qi, Min Hao Goh, Jie Wang, Shikui Han, Xue-Jun Wu, Lin Gu, Christian Kloc, Hua Zhang
      Abstract: Nanostructured transition metal dichalcogenides (TMDs) are proven to be efficient and robust earth-abundant electrocatalysts to potentially replace precious platinum-based catalysts for the hydrogen evolution reaction (HER). However, the catalytic efficiency of reported TMD catalysts is still limited by their low-density active sites, low conductivity, and/or uncleaned surface. Herein, a general and facile method is reported for high-yield, large-scale production of water-dispersed, ultrasmall-sized, high-percentage 1T-phase, single-layer TMD nanodots with high-density active edge sites and clean surface, including MoS2, WS2, MoSe2, Mo0.5W0.5S2, and MoSSe, which exhibit much enhanced electrochemical HER performances as compared to their corresponding nanosheets. Impressively, the obtained MoSSe nanodots achieve a low overpotential of −140 mV at current density of 10 mA cm−2, a Tafel slope of 40 mV dec−1, and excellent long-term durability. The experimental and theoretical results suggest that the excellent catalytic activity of MoSSe nanodots is attributed to the high-density active edge sites, high-percentage metallic 1T phase, alloying effect and basal-plane Se-vacancy. This work provides a universal and effective way toward the synthesis of TMD nanostructures with abundant active sites for electrocatalysis, which can also be used for other applications such as batteries, sensors, and bioimaging.A general and facile method is developed for high-yield, large-scale production of water-dispersed, ultrasmall, high-percentage 1T-phase, single-layer transition metal dichalcogenide nanodots with high-density active edge sites and clean surface, including MoS2, WS2, MoSe2, Mo0.5W0.5S2, and MoSSe, which exhibit much enhanced electrochemical hydrogen evolution reaction performances as compared to their corresponding nanosheets.
      PubDate: 2018-01-15T04:43:59.012905-05:
      DOI: 10.1002/adma.201705509
  • Stable High-Index Faceted Pt Skin on Zigzag-Like PtFe Nanowires Enhances
           Oxygen Reduction Catalysis
    • Authors: Mingchuan Luo; Yingjun Sun, Xu Zhang, Yingnan Qin, Mingqiang Li, Yingjie Li, Chunji Li, Yong Yang, Lei Wang, Peng Gao, Gang Lu, Shaojun Guo
      Abstract: Selectively exposing active surfaces and judiciously tuning the near-surface composition of electrode materials represent two prominent means of promoting electrocatalytic performance. Here, a new class of Pt3Fe zigzag-like nanowires (Pt-skin Pt3Fe z-NWs) with stable high-index facets (HIFs) and nanosegregated Pt-skin structure is reported, which are capable of substantially boosting electrocatalysis in fuel cells. These unique structural features endow the Pt-skin Pt3Fe z-NWs with a mass activity of 2.11 A mg−1 and a specifc activity of 4.34 mA cm−2 for the oxygen reduction reaction (ORR) at 0.9 V versus reversible hydrogen electrode, which are the highest in all reported PtFe-based ORR catalysts. Density function theory calculations reveal a combination of exposed HIFs and formation of Pt-skin structure, leading to an optimal oxygen adsorption energy due to the ligand and strain effects, which is responsible for the much enhanced ORR activities. In contrast to previously reported HIFs-based catalysts, the Pt-skin Pt3Fe z-NWs maintain ultrahigh durability with little activity decay and negligible structure transformation after 50 000 potential cycles. Overcoming a key technical barrier in electrocatalysis, this work successfully extends the nanosegregated Pt-skin structure to nanocatalysts with HIFs, heralding the exciting prospects of high-effcient Pt-based catalysts in fuel cells.A unique class of 1D zigzag-like PtFe nanowires is synthesized and further applied as the electrocatalyst toward the oxygen reduction reaction. Extremely high catalytic activity and durability is achieved, highlighting the combination of high-index facets and nanosegregated Pt-skin structure in multimetallic nanocrystals for enhanced electrocatalysis.
      PubDate: 2018-01-15T04:43:10.860097-05:
      DOI: 10.1002/adma.201705515
  • Near-Infrared Light-Sensitive Polyvinyl Alcohol Hydrogel Photoresist for
           Spatiotemporal Control of Cell-Instructive 3D Microenvironments
    • Authors: Xiao-Hua Qin; Xiaopu Wang, Markus Rottmar, Bradley J. Nelson, Katharina Maniura-Weber
      Abstract: Advanced hydrogel systems that allow precise control of cells and their 3D microenvironments are needed in tissue engineering, disease modeling, and drug screening. Multiphoton lithography (MPL) allows true 3D microfabrication of complex objects, but its biological application requires a cell-compatible hydrogel resist that is sufficiently photosensitive, cell-degradable, and permissive to support 3D cell growth. Here, an extremely photosensitive cell-responsive hydrogel composed of peptide-crosslinked polyvinyl alcohol (PVA) is designed to expand the biological applications of MPL. PVA hydrogels are formed rapidly by ultraviolet light within 1 min in the presence of cells, providing fully synthetic matrices that are instructive for cell-matrix remodeling, multicellular morphogenesis, and protease-mediated cell invasion. By focusing a multiphoton laser into a cell-laden PVA hydrogel, cell-instructive extracellular cues are site-specifically attached to the PVA matrix. Cell invasion is thus precisely guided in 3D with micrometer-scale spatial resolution. This robust hydrogel enables, for the first time, ultrafast MPL of cell-responsive synthetic matrices at writing speeds up to 50 mm s−1. This approach should enable facile photochemical construction and manipulation of 3D cellular microenvironments with unprecedented flexibility and precision.A rapidly crosslinkable polyvinyl alcohol hydrogel photoresist is developed to synthesize modular 3D cell-instructive microenvironments and to spatiotemporally control cell functions in culture via multiphoton laser at high resolution. When cultured in 3D, single epithelial cells can self-organize into miniature multicellular structures. This material allows ultrafast multiphoton photolithography and high-precision cell manipulation in 3D culture, offering unprecedented opportunities for in situ tissue engineering and cell biology.
      PubDate: 2018-01-15T04:42:36.953187-05:
      DOI: 10.1002/adma.201705564
  • High-Capacity Cathode Material with High Voltage for Li-Ion Batteries
    • Authors: Ji-Lei Shi; Dong-Dong Xiao, Mingyuan Ge, Xiqian Yu, Yong Chu, Xiaojing Huang, Xu-Dong Zhang, Ya-Xia Yin, Xiao-Qing Yang, Yu-Guo Guo, Lin Gu, Li-Jun Wan
      Abstract: Electrochemical energy storage devices with a high energy density are an important technology in modern society, especially for electric vehicles. The most effective approach to improve the energy density of batteries is to search for high-capacity electrode materials. According to the concept of energy quality, a high-voltage battery delivers a highly useful energy, thus providing a new insight to improve energy density. Based on this concept, a novel and successful strategy to increase the energy density and energy quality by increasing the discharge voltage of cathode materials and preserving high capacity is proposed. The proposal is realized in high-capacity Li-rich cathode materials. The average discharge voltage is increased from 3.5 to 3.8 V by increasing the nickel content and applying a simple after-treatment, and the specific energy is improved from 912 to 1033 Wh kg−1. The current work provides an insightful universal principle for developing, designing, and screening electrode materials for high energy density and energy quality.Li-ion batteries with high energy quality require a high capacity coupled with high operating voltage. This requires the electrode materials to not only have a high specific capacity but also a high discharge voltage for cathode materials and low charge voltage for anode materials.
      PubDate: 2018-01-15T04:42:06.538788-05:
      DOI: 10.1002/adma.201705575
  • 2D-Black-Phosphorus-Reinforced 3D-Printed Scaffolds:A Stepwise
           Countermeasure for Osteosarcoma
    • Authors: Bowen Yang; Junhui Yin, Yu Chen, Shanshan Pan, Heliang Yao, Youshui Gao, Jianlin Shi
      Abstract: With the ever-deeper understanding of nano–bio interactions and the development of fabrication methodologies of nanomaterials, various therapeutic platforms based on nanomaterials have been developed for next-generation oncological applications, such as osteosarcoma therapy. In this work, a black phosphorus (BP) reinforced 3D-printed scaffold is designed and prepared to provide a feasible countermeasure for the efficient localized treatment of osteosarcoma. The in situ phosphorus-driven, calcium-extracted biomineralization of the intra-scaffold BP nanosheets enables both photothermal ablation of osteosarcoma and the subsequent material-guided bone regeneration in physiological microenvironment, and in the meantime endows the scaffolds with unique physicochemical properties favoring the whole stepwise therapeutic process. Additionally, a corrugated structure analogous to Haversian canals is found on newborn cranial bone tissue of Sprague–Dawley rats, which may provide much inspiration for the future research of bone-tissue engineering.A stepwise nanomedical therapeutic concept is proposed for osteosarcoma therapy by integrating 2D black phosphorous nanosheets into 3D-printed bioglass scaffolds, which are capable of accomplishing combined photothermal therapy of tumors with the formation of new osseous tissue accompanying the degradation of the scaffolds, as systematically demonstrated both in vitro and in vivo.
      PubDate: 2018-01-15T04:41:32.225945-05:
      DOI: 10.1002/adma.201705611
  • Nanocage-Therapeutics Prevailing Phagocytosis and Immunogenic Cell Death
           Awakens Immunity against Cancer
    • Authors: Eun Jung Lee; Gi-Hoon Nam, Na Kyeong Lee, Minwoo Kih, Eunee Koh, Yoon Kyoung Kim, Yeonsun Hong, Soyoun Kim, Seung-Yoon Park, Cherlhyun Jeong, Yoosoo Yang, In-San Kim
      Abstract: A growing appreciation of the relationship between the immune system and the tumorigenesis has led to the development of strategies aimed at “re-editing” the immune system to kill tumors. Here, a novel tactic is reported for overcoming the activation-energy threshold of the immunosuppressive tumor microenvironment and mediating the delivery and presentation of tumor neoantigens to the host's immune system. This nature-derived nanocage not only efficiently presents ligands that enhance cancer cell phagocytosis, but also delivers drugs that induce immunogenic cancer cell death. The designed nanocage-therapeutics induce the release of neoantigens and danger signals in dying tumor cells, and leads to enhancement of tumor cell phagocytosis and cross-priming of tumor specific T cells by neoantigen peptide-loaded antigen-presenting cells. Potent inhibition of tumor growth and complete eradication of tumors is observed through systemic tumor-specific T cell responses in tumor draining lymph nodes and the spleen and further, infiltration of CD8+ T cells into the tumor site. Remarkably, after removal of the primary tumor, all mice treated with this nanocage-therapeutics are protected against subsequent challenge with the same tumor cells, suggesting development of lasting, tumor-specific responses. This designed nanocage-therapeutics “awakens” the host's immune system and provokes a durable systemic immune response against cancer.Designed nanocage-therapeutics induce the release of neoantigens and danger signals in dying cancer cells, enhance tumor cell phagocytosis, and cross-prime tumor specific T cells by neoantigen peptide-loaded antigen presenting cells (APCs). These nanocage-therapeutics ‘awaken' the host's immune system to the presence of cancer and elicit a durable systemic immune response against cancer.
      PubDate: 2018-01-15T04:40:23.574825-05:
      DOI: 10.1002/adma.201705581
  • High-Performance Organic Bulk-Heterojunction Solar Cells Based on
           Multiple-Donor or Multiple-Acceptor Components
    • Authors: Wenchao Huang; Pei Cheng, Yang (Michael) Yang, Gang Li, Yang Yang
      Abstract: Organic solar cells (OSCs) based on bulk heterojunction structures are promising candidates for next-generation solar cells. However, the narrow absorption bandwidth of organic semiconductors is a critical issue resulting in insufficient usage of the energy from the solar spectrum, and as a result, it hinders performance. Devices based on multiple-donor or multiple-acceptor components with complementary absorption spectra provide a solution to address this issue. OSCs based on multiple-donor or multiple-acceptor systems have achieved power conversion efficiencies over 12%. Moreover, the introduction of an additional component can further facilitate charge transfer and reduce charge recombination through cascade energy structure and optimized morphology. This progress report provides an overview of the recent progress in OSCs based on multiple-donor (polymer/polymer, polymer/dye, and polymer/small molecule) or multiple-acceptor (fullerene/fullerene, fullerene/nonfullerene, and nonfullerene/nonfullerene) components.This progress report provides an overview of the most impactful recent progress in high-performance organic solar cells based on multiple-donor (polymer/polymer, polymer/dye, and polymer/small molecule) or multiple-acceptor (fullerene/fullerene, fullerene/nonfullerene, and nonfullerene/nonfullerene) components, focusing particularly on the interactions between different components from the perspective of morphology and photophysics.
      PubDate: 2018-01-15T04:39:36.72468-05:0
      DOI: 10.1002/adma.201705706
  • Nickel-Based (Photo)Electrocatalysts for Hydrogen Production
    • Authors: Lvlv Ji; Cuncai Lv, Zuofeng Chen, Zhipeng Huang, Chi Zhang
      Abstract: Hydrogen is considered a promising energy carrier for replacing traditional fossil fuels. Electrochemical or solar-driven water splitting is a green and sustainable method of producing hydrogen. To lower the overpotential and minimize energy costs, numerous reports have focused on developing noble-metal-free catalysts for hydrogen production, with special attention paid to nickel-based materials. Herein, the current state of research on the use of Ni-based materials as electrocatalysts, cocatalysts, and photoactive materials in hydrogen production is reviewed. Recent research efforts toward the development of various Ni-based (photo)electrocatalysts, their applications in hydrogen production, and the corresponding mechanisms are covered. The approaches used to improve or optimize these materials are summarized, and the key remaining challenges are discussed.Recent research progress on the use of Ni-based materials as electrocatalysts, cocatalysts, and photoactive materials in hydrogen production is reviewed. Research efforts toward the development and application of these materials in hydrogen production and the corresponding mechanisms are covered. The approaches used to improve or optimize these materials are summarized, and the key remaining challenges are discussed.
      PubDate: 2018-01-15T04:38:22.499902-05:
      DOI: 10.1002/adma.201705653
  • Efficient Supercapacitor Energy Storage Using Conjugated Microporous
           Polymer Networks Synthesized from Buchwald–Hartwig Coupling
    • Authors: Yaozu Liao; Haige Wang, Meifang Zhu, Arne Thomas
      Abstract: Supercapacitors have received increasing interest as energy storage devices due to their rapid charge–discharge rates, high power densities, and high durability. In this work, novel conjugated microporous polymer (CMP) networks are presented for supercapacitor energy storage, namely 3D polyaminoanthraquinone (PAQ) networks synthesized via Buchwald–Hartwig coupling between 2,6-diaminoanthraquinone and aryl bromides. PAQs exhibit surface areas up to 600 m2 g−1, good dispersibility in polar solvents, and can be processed to flexible electrodes. The PAQs exhibit a three-electrode specific capacitance of 576 F g−1 in 0.5 m H2SO4 at a current of 1 A g−1 retaining 80–85% capacitances and nearly 100% Coulombic efficiencies (95–98%) upon 6000 cycles at a current density of 2 A g−1. Asymmetric two-electrode supercapacitors assembled by PAQs show a capacitance of 168 F g−1 of total electrode materials, an energy density of 60 Wh kg−1 at a power density of 1300 W kg−1, and a wide working potential window (0–1.6 V). The asymmetric supercapacitors show Coulombic efficiencies up to 97% and can retain 95.5% of initial capacitance undergo 2000 cycles. This work thus presents novel promising CMP networks for charge energy storage.Superior electrochemical energy storage electrodes are achieved through rational design of redox-active nitrogen-rich conjugated microporous polymers using a unique Buchwald–Hartwig coupling method. The energy storage mechanism of the polymers is illustrated, providing insights for the synthesis of electroactive materials toward efficient energy storage, batteries, and other electrochemical devices.
      PubDate: 2018-01-15T04:38:06.234036-05:
      DOI: 10.1002/adma.201705710
  • Saturable Absorption in 2D Ti3C2 MXene Thin Films for Passive Photonic
    • Authors: Yongchang Dong; Sergii Chertopalov, Kathleen Maleski, Babak Anasori, Longyu Hu, Sriparna Bhattacharya, Apparao M. Rao, Yury Gogotsi, Vadym N. Mochalin, Ramakrishna Podila
      Abstract: MXenes comprise a new class of 2D transition metal carbides, nitrides, and carbonitrides that exhibit unique light–matter interactions. Recently, 2D Ti3CNTx (Tx represents functional groups such as OH and F) was found to exhibit nonlinear saturable absorption (SA) or increased transmittance at higher light fluences, which is useful for mode locking in fiber-based femtosecond lasers. However, the fundamental origin and thickness dependence of SA behavior in MXenes remain to be understood. 2D Ti3C2Tx thin films of different thicknesses are fabricated using an interfacial film formation technique to systematically study their nonlinear optical properties. Using the open aperture Z-scan method, it is found that the SA behavior in Ti3C2Tx MXene arises from plasmon-induced increase in the ground state absorption at photon energies above the threshold for free carrier oscillations. The saturation fluence and modulation depth of Ti3C2Tx MXene is observed to be dependent on the film thickness. Unlike other 2D materials, Ti3C2Tx is found to show higher threshold for light-induced damage with up to 50% increase in nonlinear transmittance. Lastly, building on the SA behavior of Ti3C2Tx MXenes, a Ti3C2Tx MXene-based photonic diode that breaks time-reversal symmetry to achieve nonreciprocal transmission of nanosecond laser pulses is demonstrated.The propagation of light is reciprocal. Here, a novel passive optical diode that breaks reciprocity in light transmission by juxtaposing robust saturable absorption in Ti3C2Tx thin films with reverse saturation in C60 is demonstrated. Such devices are useful for passive optical isolation and possibly photonic logic circuits.
      PubDate: 2018-01-15T04:37:31.624331-05:
      DOI: 10.1002/adma.201705714
  • In Situ shRNA Synthesis on DNA–Polylactide Nanoparticles to Treat
           Multidrug Resistant Breast Cancer
    • Authors: Qianqian Ni; Fuwu Zhang, Yunlei Zhang, Guizhi Zhu, Zhe Wang, Zhaogang Teng, Chunyan Wang, Bryant C. Yung, Gang Niu, Guangming Lu, Longjiang Zhang, Xiaoyuan Chen
      Abstract: Nanomedicine has shown unprecedented potential for cancer theranostics. Nucleic acid (e.g., DNA and RNA) nanomedicines are of particular interest for combination therapy with chemotherapeutics. However, current nanotechnologies to construct such nucleic acid nanomedicines, which rely on chemical conjugation or physical complexation of nucleic acids with chemotherapeutics, have restrained their clinical translation due to limitations such as low drug loading efficiency and poor biostability. Herein, in situ rolling circle transcription (RCT) is applied to synthesize short hairpin RNA (shRNA) on amphiphilic DNA–polylactide (PLA) micelles. Core–shell PLA@poly-shRNA structures that codeliver a high payload of doxorubicin (Dox) and multidrug resistance protein 1 (MDR1) targeted shRNA for MDR breast cancer (BC) therapy are developed. DNA–PLA conjugates are first synthesized, which then self-assemble into amphiphilic DNA–PLA micelles; next, using the conjugated DNA as a promoter, poly-shRNA is synthesized on DNA–PLA micelles via RCT, generating PLA@poly-shRNA microflowers; and finally, microflowers are electrostatically condensed into nanoparticles using biocompatible and multifunctional poly(ethylene glycol)-grafted polypeptides (PPT-g-PEG). These PLA@poly-shRNA@PPT-g-PEG nanoparticles are efficiently delivered into MDR breast cancer cells and accumulated in xenograft tumors, leading to MDR1 silencing, intracellular Dox accumulation, potentiated apoptosis, and enhanced tumor therapeutic efficacy. Overall, this nanomedicine platform is promising to codeliver anticancer nucleic acid therapeutics and chemotherapeutics.Herein, an nucleic acid nanomedicine is reported using in situ synthesis of shRNA (short hairpin RNA) on DNA-polyactide micelles for co-delivery of multi-drug resistance protein 1 (MDR1)-silencing shRNA and chemotherapeutics, which is then condensed by a polypeptide copolymer. The resulting nanoparticles abrogate drug resistance, enhance cellular accumulation of doxorubicin, and inhibit tumor growth in an MDR breast cancer model.
      PubDate: 2018-01-15T04:37:08.72461-05:0
      DOI: 10.1002/adma.201705737
  • A Light Harvesting, Self-Powered Monolith Tactile Sensor Based on Electric
           Field Induced Effects in MAPbI3 Perovskite
    • Authors: Rohit Saraf; Long Pu, Vivek Maheshwari
      Abstract: Organolead trihalide perovskite MAPbI3 shows a distinctive combination of properties such as being ferroelectric and semiconducting, with ion migration effects under poling by electric fields. The combination of its ferroelectric and semiconducting nature is used to make a light harvesting, self-powered tactile sensor. This sensor interfaces ZnO nanosheets as a pressure-sensitive drain on the MAPbI3 film and once poled is operational for at least 72 h with just light illumination. The sensor is monolithic in structure, has linear response till 76 kPa, and is able to operate continuously as the energy harvesting mechanism is decoupled from its pressure sensing mechanism. It has a sensitivity of 0.57 kPa−1, which can be modulated by the strength of the poling field. The understanding of these effects in perovskite materials and their application in power source free devices are of significance to a wide array of fields where these materials are being researched and applied.The ferroelectric properties of MAPbI3 films are coupled with a dynamic drain of ZnO nanosheets to make a self-powered tactile sensor that is operational with just light illumination for at least 72 h. The device is developed by decoupling the ion migration and ferroelectric effects in these films based on poling conditions.
      PubDate: 2018-01-15T04:36:34.029435-05:
      DOI: 10.1002/adma.201705778
  • Dimeric Drug Polymeric Micelles with Acid-Active Tumor Targeting and
           FRET-Traceable Drug Release
    • Authors: Xing Guo; Lin Wang, Kayla Duval, Jing Fan, Shaobing Zhou, Zi Chen
      Abstract: Trans-activating transcriptional activator (TAT), a cell-penetrating peptide, is extensively used for facilitating cellular uptake and nuclear targeting of drug delivery systems. However, the positively charged TAT peptide strongly interacts with serum components and undergoes substantial phagocytosis by the reticuloendothelial system, causing a short blood circulation in vivo. In this work, an acid-active tumor targeting nanoplatform DA-TAT-PECL is developed to inhibit the nonspecific interactions of TAT in the bloodstream. 2,3-dimethylmaleic anhydride (DA) is used to convert the TAT's amines to carboxylic acid; the resulting DA-TAT is conjugated to poly(ethylene glycol)-poly(ε-caprolactone) (PEG-PCL, PECL) to get DA-TAT-PECL. After self-assembly into polymeric micelles, they are capable of circulating in the physiological condition for a long time and promoting cell penetration upon accumulation at the tumor site and deshielding the DA group. Moreover, camptothecin (CPT) is used as the anticancer drug and modified into a dimer (CPT)2-ss-Mal, in which two CPT molecules are connected by a reduction-labile maleimide thioether bond. The Förster resonance energy transfer signal between CPT and maleimide thioether bond is monitored to visualize the drug release process, and effective targeted delivery of antitumor drugs is demonstrated. This pH/reduction dual-responsive micelle system provides a new platform for high fidelity cancer therapy.A dimeric drug polymeric micelle with acid-active tumor targeting and Förster resonance energy transfer (FRET)-traceable drug release is successfully fabricated. It has unique features such as long blood circulation through shielding of the cationic charges of trans-activating transcriptional activator (TAT), enhanced cellular internalization by regenerating the original TAT in acidic tumor tissue, and intracellular glutathione-triggered FRET-traceable drug release.
      PubDate: 2017-12-06T08:22:06.136688-05:
      DOI: 10.1002/adma.201705436
  • Realizing Over 13% Efficiency in Green-Solvent-Processed Nonfullerene
           Organic Solar Cells Enabled by 1,3,4-Thiadiazole-Based Wide-Bandgap
    • Authors: Xiaopeng Xu; Ting Yu, Zhaozhao Bi, Wei Ma, Ying Li, Qiang Peng
      Abstract: Two novel wide-bandgap copolymers, PBDT-TDZ and PBDTS-TDZ, are developed based on 1,3,4-thiadiazole (TDZ) and benzo[1,2-b:4,5-b′]dithiophene (BDT) building blocks. These copolymers exhibit wide bandgaps over 2.07 eV and low-lying highest occupied molecular orbital (HOMO) levels below −5.35 eV, which match well with the typical low-bandgap acceptor of ITIC, resulting in a good complementary absorption from 300 to 900 nm and a low HOMO level offset (≤0.13 eV). Compared to PBDT-TDZ, PBDTS-TDZ with alkylthio side chains exhibits the stronger optical absorption, lower-lying HOMO level, and higher crystallinity. By using a single green solvent of o-xylene, PBDTS-TDZ:ITIC devices exhibit a large open-circuit voltage (Voc) up to 1.10 eV and an extremely low energy loss (Eloss) of 0.48 eV. At the same time, the desirable high short-circuit current density (Jsc) of 17.78 mA cm−2 and fill factor of 65.4% are also obtained, giving rise to a high power conversion efficiency (PCE) of 12.80% without any additive and post-treatment. When adopting a homotandem device architecture, the PCE is further improved to 13.35% (certified as 13.19%) with a much larger Voc of 2.13 V, which is the best value for any type of homotandem organic solar cells reported so far.Two novel 1,3,4-thiadiazole-based wide-bandgap copolymers, PBDT-TDZ and PBDTS-TDZ, are developed for efficient nonfullerene organic solar cells. The single-junction devices processed by a green solvent of o-xylene exhibit a high power conversion efficiency (PCE) of 12.80% with a low energy loss of 0.48 eV. The PCE is finally improved to 13.35% when using a homotandem device architecture.
      PubDate: 2017-12-06T01:52:00.710125-05:
      DOI: 10.1002/adma.201703973
  • Improved Efficiency and Stability of Perovskite Solar Cells Induced by CO
           Functionalized Hydrophobic Ammonium-Based Additives
    • Authors: Zhifang Wu; Sonia R. Raga, Emilio J. Juarez-Perez, Xuyang Yao, Yan Jiang, Luis K. Ono, Zhijun Ning, He Tian, Yabing Qi
      Abstract: Because of the rapid rise of the efficiency, perovskite solar cells are currently considered as the most promising next-generation photovoltaic technology. Much effort has been made to improve the efficiency and stability of perovskite solar cells. Here, it is demonstrated that the addition of a novel organic cation of 2-(6-bromo-1,3-dioxo-1H-benzo[de]isoquinolin-2(3H)-yl)ethan-1-ammonium iodide (2-NAM), which has strong Lewis acid and base interaction (between CO and Pb) with perovskite, can effectively increase crystalline grain size and reduce charge carrier recombination of the double cation FA0.83MA0.17PbI2.51Br0.49 perovskite film, thus boosting the efficiency from 17.1 ± 0.8% to 18.6 ± 0.9% for the 0.1 cm2 cell and from 15.5 ± 0.5% to 16.5 ± 0.6% for the 1.0 cm2 cell. The champion cell shows efficiencies of 20.0% and 17.6% with active areas of 0.1 and 1.0 cm2, respectively. Moreover, the hysteresis behavior is suppressed and the stability is improved. The result provides a promising route to further elevate efficiency and stability of perovskite solar cells by the fine tuning of triple organic cations.A new organic additive (2-NAM) is introduced into the perovskite film. The introduction of this additive boosts the efficiency from 17.1 ± 0.8% to 18.6 ± 0.9% for the 0.1 cm2 area cells and from 15.5 ± 0.5% to 16.5 ± 0.6% for the 1.0 cm2 area cells. Moreover, the hydrophobic nature of this additive effectively reduces the influence from moisture, thus enhancing the solar cell stability.
      PubDate: 2017-12-06T01:51:37.63148-05:0
      DOI: 10.1002/adma.201703670
  • Highly Deformable and See-Through Polymer Light-Emitting Diodes with
           All-Conducting-Polymer Electrodes
    • Authors: Seyoung Kee; Nara Kim, Byoungwook Park, Bong Seong Kim, Soonil Hong, Jong-Hoon Lee, Soyeong Jeong, Ahryun Kim, Soo-Young Jang, Kwanghee Lee
      Abstract: Despite the high expectation of deformable and see-through displays for future ubiquitous society, current light-emitting diodes (LEDs) fail to meet the desired mechanical and optical properties, mainly because of the fragile transparent conducting oxides and opaque metal electrodes. Here, by introducing a highly conductive nanofibrillated conducting polymer (CP) as both deformable transparent anode and cathode, ultraflexible and see-through polymer LEDs (PLEDs) are demonstrated. The CP-based PLEDs exhibit outstanding dual-side light-outcoupling performance with a high optical transmittance of 75% at a wavelength of 550 nm and with an excellent mechanical durability of 9% bending strain. Moreover, the CP-based PLEDs fabricated on 4 µm thick plastic foils with all-solution processing have extremely deformable and foldable light-emitting functionality. This approach is expected to open a new avenue for developing wearable and attachable transparent displays.Deformable and see-through polymer light-emitting diodes (PLEDs) are developed by using a highly conductive nanofibrillated conducting polymer (CP) as both ultraflexible transparent anode and cathode. The CP-based PLEDs fabricated on plastic foils with all-solution processing exhibit outstanding dual-side light-outcoupling performance and rollable/foldable light-emitting functionality with a high optical transmittance of 75% at a wavelength of 550 nm.
      PubDate: 2017-12-06T01:50:54.556241-05:
      DOI: 10.1002/adma.201703437
  • Alumina-Supported CoFe Alloy Catalysts Derived from
           Layered-Double-Hydroxide Nanosheets for Efficient Photothermal CO2
           Hydrogenation to Hydrocarbons
    • Authors: Guangbo Chen; Rui Gao, Yufei Zhao, Zhenhua Li, Geoffrey I. N. Waterhouse, Run Shi, Jiaqing Zhao, Mengtao Zhang, Lu Shang, Guiyang Sheng, Xiangping Zhang, Xiaodong Wen, Li-Zhu Wu, Chen-Ho Tung, Tierui Zhang
      Abstract: A series of novel CoFe-based catalysts are successfully fabricated by hydrogen reduction of CoFeAl layered-double-hydroxide (LDH) nanosheets at 300–700 °C. The chemical composition and morphology of the reaction products (denoted herein as CoFe-x) are highly dependent on the reduction temperature (x). CO2 hydrogenation experiments are conducted on the CoFe-x catalysts under UV–vis excitation. With increasing LDH-nanosheet reduction temperature, the CoFe-x catalysts show a progressive selectivity shift from CO to CH4, and eventually to high-value hydrocarbons (C2+). CoFe-650 shows remarkable selectivity toward hydrocarbons (60% CH4, 35% C2+). X-ray absorption fine structure, high-resolution transmission electron microscopy, Mössbauer spectroscopy, and density functional theory calculations demonstrate that alumina-supported CoFe-alloy nanoparticles are responsible for the high selectivity of CoFe-650 for C2+ hydrocarbons, also allowing exploitation of photothermal effects. This study demonstrates a vibrant new catalyst platform for harnessing clean, abundant solar-energy to produce valuable chemicals and fuels from CO2.Three unique CoFe-based catalysts are successfully fabricated via direct H2 reduction of a CoFeAl layered-double-hydroxide (CoFeAl-LDH) nanosheets precursor by varying the reduction temperature. LDH precursor reduction at temperatures above 600 °C results in the formation of CoFe-alloy nanoparticles, thereby affording a remarkable CO2 hydrogenation selectivity toward high-value (C2+) hydrocarbons under simulated solar excitation through photothermal effects.
      PubDate: 2017-12-05T05:29:28.097622-05:
      DOI: 10.1002/adma.201704663
  • Acoustic Fabrication via the Assembly and Fusion of Particles
    • Authors: Kai Melde; Eunjin Choi, Zhiguang Wu, Stefano Palagi, Tian Qiu, Peer Fischer
      Abstract: Acoustic assembly promises a route toward rapid parallel fabrication of whole objects directly from solution. This study reports the contact-free and maskless assembly, and fixing of silicone particles into arbitrary 2D shapes using ultrasound fields. Ultrasound passes through an acoustic hologram to form a target image. The particles assemble from a suspension along lines of high pressure in the image due to acoustic radiation forces and are then fixed (crosslinked) in a UV-triggered reaction. For this, the particles are loaded with a photoinitiator by solvent-induced swelling. This localizes the reaction and allows the bulk suspension to be reused. The final fabricated parts are mechanically stable and self-supporting.Rapid fabrication of self-supporting objects via acoustically directed assembly and UV-crosslinking is described. An acoustic hologram is placed in front of an ultrasound transducer to form an image. Silicone particles that have been swollen with a photoinitiator collect in the high-pressure zones of the image and are subsequently fixed via UV-triggered crosslinking. The reaction is confined to the particle assembly.
      PubDate: 2017-12-04T11:31:46.437268-05:
      DOI: 10.1002/adma.201704507
  • A Novel Acoustomicrofluidic Nebulization Technique Yielding New
           Crystallization Morphologies
    • Authors: Heba Ahmed; Lillian Lee, Connie Darmanin, Leslie Y. Yeo
      Abstract: A novel acoustic microfluidic nebulization platform is demonstrated, which, due to its unique ability to access intermediate evaporation rate regimes—significantly faster than that in slow solvent evaporation but considerably below that achieved in spray drying, is capable of producing novel crystal morphologies that have yet to be reported in both model inorganic and organic systems. In addition, the potential for simultaneously encapsulating single crystals within a biodegradable polymeric coating in a single simultaneous step together with the crystallization process as the solvent evaporates during nebulization is briefly shown. The platform not only has the potential to be highly scalable by employing a large number of these low-cost miniature devices in parallel to achieve industrially relevant particle production rates, but could also be advantageous over conventional spray drying in terms of energy utilization, given the tremendous efficiency associated with the high-frequency ultrasonic microdevice as well as its ambient temperature operation.The unique evaporation rate regime arising from a novel acoustic micronization platform is shown to produce new crystal morphologies of both organic and inorganic compounds. Its energy efficiency and potential for parallelization renders the technique an attractive alternative for large scale industrial crystallization.
      PubDate: 2017-12-04T11:31:19.620066-05:
      DOI: 10.1002/adma.201602040
  • Hole-Transfer Dependence on Blend Morphology and Energy Level Alignment in
           Polymer: ITIC Photovoltaic Materials
    • Authors: Nicholas D. Eastham; Jenna L. Logsdon, Eric F. Manley, Thomas J. Aldrich, Matthew J. Leonardi, Gang Wang, Natalia E. Powers-Riggs, Ryan M. Young, Lin X. Chen, Michael R. Wasielewski, Ferdinand S. Melkonyan, Robert P. H. Chang, Tobin J. Marks
      Abstract: Bulk-heterojunction organic photovoltaic materials containing nonfullerene acceptors (NFAs) have seen remarkable advances in the past year, finally surpassing fullerenes in performance. Indeed, acceptors based on indacenodithiophene (IDT) have become synonymous with high power conversion efficiencies (PCEs). Nevertheless, NFAs have yet to achieve fill factors (FFs) comparable to those of the highest-performing fullerene-based materials. To address this seeming anomaly, this study examines a high efficiency IDT-based acceptor, ITIC, paired with three donor polymers known to achieve high FFs with fullerenes, PTPD3T, PBTI3T, and PBTSA3T. Excellent PCEs up to 8.43% are achieved from PTPD3T:ITIC blends, reflecting good charge transport, optimal morphology, and efficient ITIC to PTPD3T hole-transfer, as observed by femtosecond transient absorption spectroscopy. Hole-transfer is observed from ITIC to PBTI3T and PBTSA3T, but less efficiently, reflecting measurably inferior morphology and nonoptimal energy level alignment, resulting in PCEs of 5.34% and 4.65%, respectively. This work demonstrates the importance of proper morphology and kinetics of ITIC donor polymer hole-transfer in boosting the performance of polymer:ITIC photovoltaic bulk heterojunction blends.Three high-fill-factor OPV polymers, PTPD3T, PBTI3T, and PBTSA3T are paired with the high performance acceptor, ITIC. A maximum power conversion efficiency of 8.43% is achieved with PTPD3T:ITIC blends due primarily to increased short-circuit current density. Ultrafast hole-transfer from ITIC to PTPD3T is observed by femtosecond transient absorption measurements due to the superior blend morphology and improved charge transport versus PBTI3T:ITIC and PBTSA3T:ITIC blends.
      PubDate: 2017-12-04T04:57:37.888702-05:
      DOI: 10.1002/adma.201704263
  • Preparation of Microcellular Epoxy Foams through a Limited-Foaming
           Process: A Contradiction with the Time–Temperature–Transformation Cure
    • Authors: Lijun Wang; Chun Zhang, Wei Gong, Yubi Ji, Shuhao Qin, Li He
      Abstract: 3D cross-linking networks are generated through chemical reactions between thermosetting epoxy resin and hardener during curing. The curing degree of epoxy material can be increased by increasing curing temperature and/or time. The epoxy material must then be fully cured through a postcuring process to optimize its material characteristics. Here, a limited-foaming method is introduced for the preparation of microcellular epoxy foams (Lim-foams) with improved cell morphology, high thermal expansion coefficient, and good compressive properties. Lim-foams exhibit a lower glass transition temperature (Tg) and curing degree than epoxy foams fabricated through free-foaming process (Fre-foams). Surprisingly, however, the Tg of Lim-foams is unaffected by postcuring temperature and time. This phenomenon, which is related to high gas pressure in the bubbles, contradicts that indicated by the time–temperature–transformation cure diagram. High bubble pressure promotes the movement of molecular chains under heating at low temperature and simultaneously suppresses the etherification cross-linking reaction during post-curing.A new molecular mechanism of the curing of epoxy foams fabricated through a limited-foaming process is proposed. These foams exhibit two distinctive Tg, which are unaffected by postcuring temperature and time. High gas pressure in the bubbles promotes the movement of molecular chains under heating at low temperature and simultaneously suppresses the later cross-linking reaction during postcuring.
      PubDate: 2017-12-04T04:57:12.790935-05:
      DOI: 10.1002/adma.201703992
  • Fine-Tuning the Energy Levels of a Nonfullerene Small-Molecule Acceptor to
           Achieve a High Short-Circuit Current and a Power Conversion Efficiency
           over 12% in Organic Solar Cells
    • Authors: Bin Kan; Jiangbin Zhang, Feng Liu, Xiangjian Wan, Chenxi Li, Xin Ke, Yunchuang Wang, Huanran Feng, Yamin Zhang, Guankui Long, Richard H. Friend, Artem A. Bakulin, Yongsheng Chen
      Abstract: Organic solar cell optimization requires careful balancing of current–voltage output of the materials system. Here, such optimization using ultrafast spectroscopy as a tool to optimize the material bandgap without altering ultrafast photophysics is reported. A new acceptor–donor–acceptor (A–D–A)-type small-molecule acceptor NCBDT is designed by modification of the D and A units of NFBDT. Compared to NFBDT, NCBDT exhibits upshifted highest occupied molecular orbital (HOMO) energy level mainly due to the additional octyl on the D unit and downshifted lowest unoccupied molecular orbital (LUMO) energy level due to the fluorination of A units. NCBDT has a low optical bandgap of 1.45 eV which extends the absorption range toward near-IR region, down to ≈860 nm. However, the 60 meV lowered LUMO level of NCBDT hardly changes the Voc level, and the elevation of the NCBDT HOMO does not have a substantial influence on the photophysics of the materials. Thus, for both NCBDT- and NFBDT-based systems, an unusually slow (≈400 ps) but ultimately efficient charge generation mediated by interfacial charge-pair states is observed, followed by effective charge extraction. As a result, the PBDB-T:NCBDT devices demonstrate an impressive power conversion efficiency over 12%—among the best for solution-processed organic solar cells.An acceptor-donor-acceptor nonfullerene acceptor NCBDT is reported. NCBDT exhibits a low optical bandgap of 1.45 eV and broadened absorption range. The PBDB-T:NCBDT-based device achieves an impressive PCE of 12.12% and Jsc over 20 mA cm-2—one of the best results for solution-processed OSCs. Further photophysical study reveals slow (≈400 ps) yet efficient free charge generation.
      PubDate: 2017-12-04T04:52:15.641685-05:
      DOI: 10.1002/adma.201704904
  • Synergism of Rare Earth Trihydrides and Graphite in Lithium Storage:
           Evidence of Hydrogen-Enhanced Lithiation
    • Authors: Xinyao Zheng; Chengkai Yang, Xinghua Chang, Teng Wang, Meng Ye, Jing Lu, Henghui Zhou, Jie Zheng, Xingguo Li
      Abstract: The lithium storage capacity of graphite can be significantly promoted by rare earth trihydrides (REH3, RE = Y, La, and Gd) through a synergetic mechanism. High reversible capacity of 720 mA h g−1 after 250 cycles is achieved in YH3–graphite nanocomposite, far exceeding the total contribution from the individual components and the effect of ball milling. Comparative study on LaH3–graphite and GdH3–graphite composites suggests that the enhancement factor is 3.1–3.4 Li per active H in REH3, almost independent of the RE metal, which is evident of a hydrogen-enhanced lithium storage mechanism. Theoretical calculation suggests that the active H from REH3 can enhance the Li+ binding to the graphene layer by introducing negatively charged sites, leading to energetically favorable lithiation up to a composition Li5C16H instead of LiC6 for conventional graphite anode.The trihydride–dihydride conversion of rare earth (RE, RE = Y, La, and Gd) generates active H with hydridic nature, which can enhance the Li+ binding to the graphene layers. This novel H-enhanced lithiation mechanism can significantly promote the lithium storage capacity of graphite.
      PubDate: 2017-12-04T04:51:21.394707-05:
      DOI: 10.1002/adma.201704353
  • A 3D Self-Shaping Strategy for Nanoresolution Multicomponent Architectures
    • Authors: Meng Su; Zhandong Huang, Yifan Li, Xin Qian, Zheng Li, Xiaotian Hu, Qi Pan, Fengyu Li, Lihong Li, Yanlin Song
      Abstract: 3D printing or fabrication pursues the essential surface behavior manipulation of droplets or a liquid for rapidly and precisely constructing 3D multimaterial architectures. Further development of 3D fabrication desires a self-shaping strategy that can heterogeneously integrate functional materials with disparate electrical or optical properties. Here, a 3D liquid self-shaping strategy is reported for rapidly patterning materials over a series of compositions and accurately achieving micro- and nanoscale structures. The predesigned template selectively pins the droplet, and the surface energy minimization drives the self-shaping processing. The as-prepared 3D circuits assembled by silver nanoparticles carry a current of 208–448 µA at 0.01 V impressed voltage, while the 3D architectures achieved by two different quantum dots show noninterfering optical properties with feature resolution below 3 µm. This strategy can facilely fabricate micro-nanogeometric patterns without a modeling program, which will be of great significance for the development of 3D functional devices.A 3D self-shaping strategy is proposed for rapidly patterning different materials and accurately achieving micro- and nanoscale structures. Micro-nanogeometric patterns can be achieved without a modeling program, which will be of great significance for the development of 3D devices.
      PubDate: 2017-12-04T02:35:05.491889-05:
      DOI: 10.1002/adma.201703963
  • Thermally Induced Bending of ReS2 Nanowalls
    • Authors: Qin Zhang; Wenjie Wang, Jiaqian Zhang, Xiaohui Zhu, Lei Fu
      Abstract: Among the variety of stimuli-responsive materials, temperature-responsive materials (TRMs) can adapt to the surrounding environment in the presence of a thermal stimulus, and they have attracted considerable attention in sensors, actuators, and surface engineering. However, polymers, as the most representative TRMs, are far from ideal with respect to long-term reliability and durability. Here, for the first time, an inorganic material, ReS2, is analyzed, which possesses an unexpected temperature-responsive behavior that is triggered by stable and reversible thermally induced bending (TIB). Due to thermal fluctuations in the ReS2 layers, intrinsic ripples tend to aggravate rapidly with rising temperature. Then, the weak interlayer interaction of ReS2 is further weakened, thus resulting in interlayer sliding. Due to a decrease in bending rigidity with increasing temperature, out-of-plane bending spontaneously occurs in the ReS2 layers. Interestingly, this TIB of ReS2 can recover to its initial configuration when the temperature drops, which is further confirmed by the reversible wetting measurement. Above all, the TIB behavior of ReS2 exhibits great potential in smart applications, such as smart windows and microfluidic devices, and fills the significant gaps of inorganic TRMs.An inorganic material, ReS2, is demonstrated, which unexpectedly possesses temperature-responsive behavior that is implemented by stable and reversible thermally induced bending (TIB). Triggered by thermal fluctuations, the TIB process relies on ripple evolution, interlayer sliding, and out-of-plane bending. The TIB of ReS2 recovers to the original configuration when the temperature decreases, which is further confirmed by reversible wetting measurements.
      PubDate: 2017-12-04T02:31:20.52072-05:0
      DOI: 10.1002/adma.201704585
  • Highly Stretchable and Reliable, Transparent and Conductive Entangled
           Graphene Mesh Networks
    • Authors: Jaehyun Han; Jun-Young Lee, Jihye Lee, Jong-Souk Yeo
      Abstract: A highly stretchable and reliable, transparent and conductive entangled graphene mesh network (EGMN) exhibits an interconnected percolation network, as usually shown in 1D nanowires, but with the electrical, mechanical, and thermal properties of 2D graphene. The unique combination of the 2D material properties and the network structure of wrinkled, waved, and crumpled graphene enables the EGMN to demonstrate excellent electrical reliability, mechanical durability, and thermal stability, even under harsh environmental and external conditions such as very high temperature, humidity, bending, and stretching. Specifically, after 100 000 cycles of bending with radius of 2 mm, the EGMN maintains its resistance similar to its initial value. The EGMN shows a steady monotonic response in resistance to strain cycles of 50 000 times with nearly constant gauge factors of 0.76, 1.67, and 2.55 at 10%, 40%, and 70% strains, respectively. Moreover, the EGMN shows very little change in resistance with the temperature increasing up to 1000 °C, by in situ thermal analysis with transmission electron microscopy and also by long-term stability testing at 70 °C and 70% relative humidity for 30 d. These results demonstrate that this novel entangled graphene mesh network can significantly broaden the application areas for various types of wearable and stretchable devices.A highly stretchable and reliable, transparent and conductive entangled graphene mesh network (EGMN) exhibits an interconnected percolation network of 2D graphene. The unique combination of 2D material and structure in the EGMN enables excellent electrical reliability, mechanical durability, and environmental robustness. Therefore, the EGMN provides broad applicability to wearable and stretchable devices for challenging requirements such as high stretchability, temperature, and humidity.
      PubDate: 2017-12-04T02:26:59.654921-05:
      DOI: 10.1002/adma.201704626
  • Structuring of Functional Spider Silk Wires, Coatings, and Sheets by
           Self-Assembly on Superhydrophobic Pillar Surfaces
    • Authors: Linnea Gustafsson; Ronnie Jansson, My Hedhammar, Wouter van der Wijngaart
      Abstract: Spider silk has recently become a material of high interest for a large number of biomedical applications. Previous work on structuring of silk has resulted in particles (0D), fibers (1D), films (2D), and foams, gels, capsules, or microspheres (3D). However, the manufacturing process of these structures is complex and involves posttreatment of chemicals unsuitable for biological applications. In this work, the self-assembly of recombinant spider silk on micropatterned superhydrophobic surfaces is studied. For the first time, structuring of recombinant spider silk is achieved using superhydrophobic surfaces under conditions that retain the bioactivity of the functionalized silk. By tuning the superhydrophobic surface geometry and the silk solution handling parameters, this approach allows controlled generation of silk coatings, nanowires, and sheets. The underlying mechanisms and governing parameters are discussed. It is believed that the results of this work pave the way for fabrication of silk formations for applications including vehicles for drug delivery, optical sensing, antimicrobial coatings, and cell culture scaffolds.Superhydrophobic surfaces are used to pattern bioactive silk under mild conditions, preserving its bioactivity. The interaction between the liquid:solid and the liquid:air interfaces supports spontaneous transformation of soluble silk proteins to defined silk structures. Using this approach, silk in the form of localized coatings, directional nanowires, and sheets is generated.
      PubDate: 2017-12-04T02:00:00.708583-05:
      DOI: 10.1002/adma.201704325
  • A Li–Air Battery with Ultralong Cycle Life in Ambient Air
    • Authors: Lie Wang; Jian Pan, Ye Zhang, Xunliang Cheng, Lianmei Liu, Huisheng Peng
      Abstract: The Li–air battery represents a promising power candidate for future electronics due to its extremely high energy density. However, the use of Li–air batteries is largely limited by their poor cyclability in ambient air. Herein, Li–air batteries with ultralong 610 cycles in ambient air are created by combination of low-density polyethylene film that prevents water erosion and gel electrolyte that contains a redox mediator of LiI. The low-density polyethylene film can restrain the side reactions of the discharge product of Li2O2 to Li2CO3 in ambient air, while the LiI can facilitate the electrochemical decomposition of Li2O2 during charging, which improves the reversibility of the Li–air battery. All the components of the Li–air battery are flexible, which is particularly desirable for portable and wearable electronic devices.Li–air batteries with ultralong 610 cycles in ambient air are achieved by combination of low-density polyethylene film that prevents water erosion and gel electrolyte that contains a redox mediator of LiI. All the components of the Li–air battery are also flexible, which is promising for various fields such as portable and wearable electronics.
      PubDate: 2017-12-01T03:21:15.569814-05:
      DOI: 10.1002/adma.201704378
  • Hyperstage Graphite: Electrochemical Synthesis and Spontaneous Reactive
    • Authors: Intak Jeon; Bora Yoon, Maggie He, Timothy M. Swager
      Abstract: Covalent modification of the π-electron basal planes of graphene enables the formation of new materials with enhanced functionality. An electrochemical method is reported for the formation of what is referred to as a Hyperstage-1 graphite intercalation compound (GIC), which has a very large interlayer spacing d001> 15.3 Å and contains disordered interstitial molecules/ions. This material is highly activated and undergoes spontaneous exfoliation when reacted with diazonium ions to produce soluble graphenes with high functionalization densities of one pendant aromatic ring for every 12 graphene carbons. Critical to achieving high functionalization density is the Hyperstage-1 GIC state, a weakening of the van der Waals coupling between adjacent graphene layers, and the ability of reactants to diffuse into the disordered intercalate phase between the layers. Graphene functionalization with 3,5-dinitrophenyl groups provides for exceptional dispersibility (0.24 mg mL−1) in N,N-dimethylformamide and for conjugation with amines.Hyperstage-1 graphite intercalation compound (GIC) has a very large interlayer spacing d001> 15.3 Å and contains disordered interstitial molecules/ions. The GIC is highly activated and undergoes spontaneous exfoliation when reacted with diazonium ions to produce soluble graphenes with high functionalization densities of one pendant aromatic ring for every 12 graphene carbons.
      PubDate: 2017-12-01T03:15:56.946316-05:
      DOI: 10.1002/adma.201704538
  • Dry Etching with Nanoparticles: Formation of High Aspect-Ratio Pores and
           Channels Using Magnetic Gold Nanoclusters
    • Authors: Naveen Reddy Kadasala; Mojib Saei, Gary J. Cheng, Alexander Wei
      Abstract: Methods for generating nanopores in substrates typically involve one or more wet-etching steps. Here a fundamentally different approach to produce nanopores in sheet substrates under dry, ambient conditions, using nanosecond-pulsed laser irradiation and magnetic gold nanoclusters (MGNCs) as the etching agents is described. Thermoplastic films (50–75 µm thickness) are coated with MGNCs then exposed to laser pulses with a coaxial magnetic field gradient, resulting in high-aspect ratio channels with tapered cross sections as characterized by confocal fluorescence tomography. The dry-etching process is applicable to a wide variety of substrates ranging from fluoropolymers to borosilicate glass, with etch rates in excess of 1 µm s–1. Finite-element modeling suggests that the absorption of laser pulses by MGNCs can produce temperature spikes of nearly 1000 °C, which is sufficient for generating photoacoustic responses that can drive particles into the medium, guided by magnetomotive force.Magnetic gold nanoclusters can be used to etch high-aspect ratio pores and channels into thermoplastic films and glass upon the absorption of laser pulses. Photothermal effects act cooperatively with magnetomotive forces under ambient conditions, making this process efficient and practical.
      PubDate: 2017-11-30T05:41:39.464209-05:
      DOI: 10.1002/adma.201703091
  • Thermodynamics and Kinetics of Sulfur Cathode during Discharge in
           MgTFSI2–DME Electrolyte
    • Authors: Tao Gao; Xiao Ji, Singyuk Hou, Xiulin Fan, Xiaogang Li, Chongying Yang, Fudong Han, Fei Wang, Jianjun Jiang, Kang Xu, Chunsheng Wang
      Abstract: Rechargeable magnesium/sulfur battery is of significant interest because its energy density (1700 Wh kg−1 and 3200 Wh L−1) is among the highest of all battery chemistries (lower than Li/O2 and Mg/O2 but comparable to Li/S), and Mg metal allows reversible operation (100% Coulombic efficiency) with no dendrite formation. This great promise is already justified in some early reports. However, lack of mechanistic study of sulfur reaction in the Mg cation environment has severely hindered our understanding and prevents effective measures for performance improvement. In this work, the very first systematic fundamental study on Mg/S system is conducted by combining experimental methods with computational approach. The thermodynamics and reaction pathway of sulfur cathode in MgTFSI2–DME electrolyte, as well as the associated kinetics are thoroughly investigated. The results here reveal that sulfur undergoes a consecutive staging pathway in which the formation and chain-shortening of polysulfide occur at early stage accompanied by the dissolution of long-chain polysulfide, and solid-state transition from short-chain polysulfide to magnesium sulfide occurs at late stage. The former process is much faster than the latter due to the synergetic effect of the mediating effect of dissolved polysulfide and the fast diffusion of Mg ion in the amorphous intermediate.The very first systematic fundamental study on a Mg/S system by combining experimental methods with a computational approach is conducted. The thermodynamics and the reaction pathway of sulfur cathode in MgTFSI2–DME electrolyte, as well as the associated kinetics are thoroughly investigated.
      PubDate: 2017-11-30T05:40:57.49462-05:0
      DOI: 10.1002/adma.201704313
  • Black Phosphorus Nanosheets as a Neuroprotective Nanomedicine for
           Neurodegenerative Disorder Therapy
    • Authors: Wansong Chen; Jiang Ouyang, Xinyao Yi, Yan Xu, Chengcheng Niu, Weiyu Zhang, Liqiang Wang, Jianping Sheng, Liu Deng, You-Nian Liu, Shaojun Guo
      Abstract: Transition-metal dyshomeostasis is recognized as a critical pathogenic factor at the onset and progression of neurodegenerative disorder (ND). Excess transition-metal ions such as Cu2+ can catalyze the generation of cytotoxic reactive oxygen species and thereafter induce neuronal cell apoptosis. Exploring new chelating agents, which are not only capable of capturing excess redox-active metal, but can also cross the blood–brain barrier (BBB), are highly desired for ND therapy. Herein, it is demonstrated that 2D black phosphorus (BP) nanosheets can capture Cu2+ efficiently and selectively to protect neuronal cells from Cu2+-induced neurotoxicity. Moreover, both in vitro and in vivo studies show that the BBB permeability of BP nanosheets is significantly improved under near-infrared laser irradiation due to their strong photothermal effect, which overcomes the drawback of conventional chelating agents. Furthermore, the excellent biocompatibility and stability guarantee the biosafety of BP in future clinical applications. Therefore, these features make BP nanosheets have the great potential to work as an efficient neuroprotective nanodrug for ND therapy.Black phosphorus (BP) nanosheets, having the capability of capturing Cu2+ efficiently and selectively, can not only act as an antioxidant to extenuate cellular oxidative stress and inhibit cell apoptosis, but also improve the blood–brain barrier permeability under near-infrared laser irradiation through the photothermal effect. These properties of BP nanosheets make them an efficient neuroprotective nanodrug for neurodegenerative disorder therapy.
      PubDate: 2017-11-30T05:37:25.605845-05:
      DOI: 10.1002/adma.201703458
  • Photonic Crystal Phosphors Integrated on a Blue LED Chip for Efficient
           White Light Generation
    • Authors: Jongho Lee; Kyungtaek Min, Yeonsang Park, Kyung-Sang Cho, Heonsu Jeon
      Abstract: Following the proof-of-concept experiment in the unit structure level, photonic crystal (PhC) phosphors—structurally engineered phosphor materials based on the nanophotonics principles—are integrated with a blue light-emitting diode (LED) chip to demonstrate a compact and efficient white light source. Red- or green-emitting CdSe-based colloidal quantum dots (CQDs) are coated on a Si3N4 thin-film grating to fabricate PhC phosphors. The underlying PhC structure is designed such that the photonic band-edge modes at the zone center (k∣∣ = 0) are tuned to the energy of the blue excitation photons. By progressively stacking the PhC phosphor plates on a blue LED chip, the blue, green, and red emission intensities can be tightly controlled to obtain white light with the desired properties. The chromaticity coordinates, (0.332, 0.341), and correlated color temperature, 5500 K, are obtained from a stack of 3 red and 11 green PhC phosphor plates; in contrast, a stack of 5 red and 16 green reference phosphor plates are required to generate a similar white light. Overall, the PhC phosphors produce 8% higher total emission intensity out of 33% less amount of CQDs than the reference phosphors.An efficient white light source using structurally engineered phosphors is demonstrated. Photonic crystal phosphor structures composed of red and green colloidal quantum dots are stacked on a blue light-emitting diode chip. When photonic band-edge modes are in resonance with the energy of blue excitation photons, white light of an intensity exceeding that from the reference device is generated, yet with a significantly reduced amount of phosphor materials.
      PubDate: 2017-11-30T05:36:47.713581-05:
      DOI: 10.1002/adma.201703506
  • Influence of Radiation on the Properties and the Stability of Hybrid
    • Authors: Felix Lang; Oleksandra Shargaieva, Viktor V. Brus, Heinz C. Neitzert, Jörg Rappich, Norbert H. Nickel
      Abstract: Organic–inorganic perovskites are well suited for optoelectronic applications. In particular, perovskite single and perovskite tandem solar cells with silicon are close to their market entry. Despite their swift rise in efficiency to more than 21%, solar cell lifetimes are way below the needed 25 years. In fact, comparison of the time when the device performance has degraded to 80% of its initial value (T80 lifetime) of numerous solar cells throughout the literature reveals a strongly reduced stability under illumination. Herein, the various detrimental effects are discussed. Most notably, moisture- and heat-related degradation can be mitigated easily by now. Recently, however, several photoinduced degradation mechanisms have been observed. Under illumination, mixed perovskites tend to phase segregate, while, further, oxygen catalyzes deprotonation of the organic cations. Additionally, during illumination photogenerated charge can be trapped in the NH antibonding orbitals causing dissociation of the organic cation. On the other hand, organic–inorganic perovskites exhibit a high radiation hardness that is superior to crystalline silicon. Here, the proposed degradation mechanisms reported in the literature are thoroughly reviewed and the microscopic mechanisms and their implications for solar cells are discussed.T80 lifetimes of organic–inorganic perovskite solar cells are strongly reduced under illumination. Various degradation mechanisms are therefore discussed throughout the literature. Degradation by moisture or heat is well understood and mitigation possible. Photoinduced phase segregation and photoinduced dissociation of the organic cation, however, remain unsolved. Recent observations enlighten the underlying microscopic mechanisms and may pave the way for stable perovskites.
      PubDate: 2017-11-20T01:46:30.241467-05:
      DOI: 10.1002/adma.201702905
  • Solution Adsorption Formation of a π-Conjugated Polymer/Graphene
           Composite for High-Performance Field-Effect Transistors
    • Authors: Yun Liu; Wei Hao, Huiying Yao, Shuzhou Li, Yuchen Wu, Jia Zhu, Lei Jiang
      Abstract: Semiconducting polymers with π-conjugated electronic structures have potential application in the large-scale printable fabrication of high-performance electronic and optoelectronic devices. However, owing to their poor environmental stability and high-cost synthesis, polymer semiconductors possess limited device implementation. Here, an approach for constructing a π-conjugated polymer/graphene composite material to circumvent these limitations is provided, and then this material is patterned into 1D arrays. Driven by the π–π interaction, several-layer polymers can be adsorbed onto the graphene planes. The low consumption of the high-cost semiconductor polymers and the mass production of graphene contribute to the low-cost fabrication of the π-conjugated polymer/graphene composite materials. Based on the π-conjugated system, a reduced π–π stacking distance between graphene and the polymer can be achieved, yielding enhanced charge-transport properties. Owing to the incorporation of graphene, the composite material shows improved thermal stability. More generally, it is believed that the construction of the π-conjugated composite shows clear possibility of integrating organic molecules and 2D materials into microstructure arrays for property-by-design fabrication of functional devices with large area, low cost, and high efficiency.π-conjugated polymer/graphene composite arrays are constructed for enhancing the charge-carrier transport and thermal stability with a low polymer consumption. By employing an asymmetric wettability assembly system, the composite material is integrated into 1D arrays. Owing to the strong π–π interaction, charge transfer from conjugated polymers to graphene provides an efficient pathway for carrier transport.
      PubDate: 2017-11-17T09:27:34.105814-05:
      DOI: 10.1002/adma.201705377
  • Hybridization of MOFs and COFs: A New Strategy for Construction of MOF@COF
           Core–Shell Hybrid Materials
    • Authors: Yongwu Peng; Meiting Zhao, Bo Chen, Zhicheng Zhang, Ying Huang, Fangna Dai, Zhuangchai Lai, Xiaoya Cui, Chaoliang Tan, Hua Zhang
      Abstract: The exploration of new porous hybrid materials is of great importance because of their unique properties and promising applications in separation of materials, catalysis, etc. Herein, for the first time, by integration of metal–organic frameworks (MOFs) and covalent organic frameworks (COFs), a new type of MOF@COF core–shell hybrid material, i.e., NH2-MIL-68@TPA-COF, with high crystallinity and hierarchical pore structure, is synthesized. As a proof-of-concept application, the obtained NH2-MIL-68@TPA-COF hybrid material is used as an effective visible-light-driven photocatalyst for the degradation of rhodamine B. The synthetic strategy in this study opens up a new avenue for the construction of other MOF–COF hybrid materials, which could have various promising applications.By integration of metal–organic frameworks (MOFs) and covalent organic frameworks (COFs), a new type of MOF@COF core–shell hybrid material, i.e., NH2-MIL-68@TPA-COF, with high crystallinity and hierarchical pore structure, is synthesized. The obtained hybrid material can be used as an effective visible-light-driven photocatalyst for the degradation of rhodamine B.
      PubDate: 2017-11-14T02:34:25.972011-05:
      DOI: 10.1002/adma.201705454
  • Perovskite Solar Cells with ZnO Electron-Transporting Materials
    • Authors: Peng Zhang; Jiang Wu, Ting Zhang, Yafei Wang, Detao Liu, Hao Chen, Long Ji, Chunhua Liu, Waseem Ahmad, Zhi David Chen, Shibin Li
      Abstract: Perovskite solar cells (PSCs) have developed rapidly over the past few years, and the power conversion efficiency of PSCs has exceeded 20%. Such high performance can be attributed to the unique properties of perovskite materials, such as high absorption over the visible range and long diffusion length. Due to the different diffusion lengths of holes and electrons, electron transporting materials (ETMs) used in PSCs play a critical role in PSCs performance. As an alternative to TiO2 ETM, ZnO materials have similar physical properties to TiO2 but with much higher electron mobility. In addition, there are many simple and facile methods to fabricate ZnO nanomaterials with low cost and energy consumption. This review focuses on recent developments in the use of ZnO ETM for PSCs. The fabrication methods of ZnO materials are briefly introduced. The influence of different ZnO ETMs on performance of PSCs is then reviewed. The limitations of ZnO ETM-based PSCs and some solutions to these challenges are also discussed. The review provides a systematic and comprehensive understanding of the influence of different ZnO ETMs on PSCs performance and potentially motivates further development of PSCs by extending the knowledge of ZnO-based PSCs to TiO2-based PSCs.Progress in perovskite solar cells based on ZnO electron-transport materials of different morphologies and their fabrication methods is summarized. The influence of the ZnO morphology and fabrication process on the performance of perovskite solar cells are reviewed and highlighted. Moreover, the issues of ZnO materials, and some solutions and strategies to promote the performance of solar cells, are introduced.
      PubDate: 2017-11-06T04:37:19.123635-05:
      DOI: 10.1002/adma.201703737
  • Nanofluidics: A New Arena for Materials Science
    • Authors: Yan Xu
      Abstract: A significant growth of research in nanofluidics is achieved over the past decade, but the field is still facing considerable challenges toward the transition from the current physics-centered stage to the next application-oriented stage. Many of these challenges are associated with materials science, so the field of nanofluidics offers great opportunities for materials scientists to exploit. In addition, the use of unusual effects and ultrasmall confined spaces of well-defined nanofluidic environments would offer new mechanisms and technologies to manipulate nanoscale objects as well as to synthesize novel nanomaterials in the liquid phase. Therefore, nanofluidics will be a new arena for materials science. In the past few years, burgeoning progress has been made toward this trend, as overviewed in this article, including materials and methods for fabricating nanofluidic devices, nanofluidics with functionalized surfaces and functional material components, as well as nanofluidics for manipulating nanoscale materials and fabricating new nanomaterials. Many critical challenges as well as fantastic opportunities in this arena lie ahead. Some of those, which are of particular interest, are also discussed.The use of nanofluidics opens up a new arena for materials science. Burgeoning progress is made, including new materials and methods for fabricating nanofluidic devices, nanofluidics with functionalized surfaces and functional material components, as well as nanofluidics for manipulating nanoscale materials and fabricating new nanomaterials.
      PubDate: 2017-11-02T02:23:27.289875-05:
      DOI: 10.1002/adma.201702419
  • Microporous Organic Materials for Membrane-Based Gas Separation
    • Authors: Xiaoqin Zou; Guangshan Zhu
      Abstract: Membrane materials with excellent selectivity and high permeability are crucial to efficient membrane gas separation. Microporous organic materials have evolved as an alternative candidate for fabricating membranes due to their inherent attributes, such as permanent porosity, high surface area, and good processability. Herein, a unique pore-chemistry concept for the designed synthesis of microporous organic membranes, with an emphasis on the relationship between pore structures and membrane performances, is introduced. The latest advances in microporous organic materials for potential membrane application in gas separation of H2, CO2, O2, and other industrially relevant gases are summarized. Representative examples of the recent progress in highly selective and permeable membranes are highlighted with some fundamental analyses from pore characteristics, followed by a brief perspective on future research directions.Recent advances regarding microporous organic materials for membrane gas separation are reviewed. Critical challenges associated with the designed synthesis of membrane materials with defined porous structures, and the correlations between pore chemistry and membrane separation performance, in terms of selectivity and permeability, are discussed.
      PubDate: 2017-10-24T06:28:25.6607-05:00
      DOI: 10.1002/adma.201700750
  • Evolutionary Metal Oxide Clusters for Novel Applications: Toward
           High-Density Data Storage in Nonvolatile Memories
    • Authors: Xiaoli Chen; Ye Zhou, Vellaisamy A. L. Roy, Su-Ting Han
      Abstract: Because of current fabrication limitations, miniaturizing nonvolatile memory devices for managing the explosive increase in big data is challenging. Molecular memories constitute a promising candidate for next-generation memories because their properties can be readily modulated through chemical synthesis. Moreover, these memories can be fabricated through mild solution processing, which can be easily scaled up. Among the various materials, polyoxometalate (POM) molecules have attracted considerable attention for use as novel data-storage nodes for nonvolatile memories. Here, an overview of recent advances in the development of POMs for nonvolatile memories is presented. The general background knowledge of the structure and property diversity of POMs is also summarized. Finally, the challenges and perspectives in the application of POMs in memories are discussed.The application of clusters of polyoxometalates (POMs) in electronic devices, particularly in memory devices is discussed. The multielectron redox behavior and high chemical stability and tenability, as well as the compatibility with nanoscale-level scaling-down techniques are impressive figures of merits. POMs can be used in a wide range of fields, from chemistry to catalysis, and from memory devices to energy-storage devices.
      PubDate: 2017-10-23T07:30:40.19814-05:0
      DOI: 10.1002/adma.201703950
  • Directed Self-Assembly of Liquid-Crystalline Molecular Building Blocks for
           Sub-5 nm Nanopatterning
    • Authors: Koen Nickmans; Albert P. H. J. Schenning
      Abstract: The thin-film directed self-assembly of molecular building blocks into oriented nanostructure arrays enables next-generation lithography at the sub-5 nm scale. Currently, the fabrication of inorganic arrays from molecular building blocks is restricted by the limited long-range order and orientation of the materials, as well as suitable methodologies for creating lithographic templates at sub-5 nm dimensions. In recent years, higher-order liquid crystals have emerged as functional thin films for organic electronics, nanoporous membranes, and templated synthesis, which provide opportunities for their use as lithographic templates. By choosing examples from these fields, recent progress toward the design of molecular building blocks is highlighted, with an emphasis on liquid crystals, to access sub-5 nm features, their directed self-assembly into oriented thin films, and, importantly, the fabrication of inorganic arrays. Finally, future challenges regarding sub-5 nm patterning with liquid crystals are discussed.Emerging approaches to sub-5 nm patterning with molecular building blocks are discussed, emphasizing the use of liquid-crystalline materials to access sub-5 nm features, their directed self-assembly into oriented thin films, and the fabrication of inorganic arrays. Examples are chosen from the established fields of organic electronics, nanoporous membranes, and templated synthesis, each of which provides opportunities for nanolithography.
      PubDate: 2017-10-20T06:27:57.885507-05:
      DOI: 10.1002/adma.201703713
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