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Transmission electron microscopy (TEM) is a powerful tool for unveiling the structural, compositional, and electronic properties of organic-inorganic hybrid perovskites (OIHPs) at the atomic to micrometer length scales. However, the structural and compositional instability of OIHPs under electron beam radiation results in misunderstandings of the microscopic structure-property-performance relationship in OIHP devices. Here, ultralow dose TEM is utilized to identify the mechanism of the electron-beam-induced changes in OHIPs and clarify the cumulative electron dose thresholds (critical dose) of different commercially interesting state-of-the-art OIHPs, including methylammonium lead iodide (MAPbI(3)), formamidinium lead iodide (FAPbI(3)), FA(0.83)Cs(0.17)PbI(3), FA(0.15)Cs(0.85)PbI(3), and MAPb(0.5)Sn(0.5)I(3). The critical dose is related to the composition of the OIHPs, with FA(0.15)Cs(0.85)PbI(3) having the highest critical dose of approximate to 84 e angstrom(-2) and FA(0.83)Cs(0.17)PbI(3) having the lowest critical dose of approximate to 4.2 e angstrom(-2). The electron beam irradiation results in the formation of a superstructure with ordered I and FA vacancies along (c), as identified from the three major crystal axes in cubic FAPbI(3), (c), (c), and (c). The intragrain planar defects in FAPbI(3) are stable, while an obvious modification is observed in FA(0.83)Cs(0.17)PbI(3) under continuous electron beam exposure. This information can serve as a guide for ensuring a reliable understanding of the microstructure of OIHP optoelectronic devices by TEM.

Lignocellulosic biomass photoreforming is a promising and alternative strategy for both sustainable H2 production and biomass valorization with infinite solar energy. However, harsh reaction conditions (high alkalinity or toxic organic solvents), with low biomass conversion and selectivity are often reported in literature. In this work, we report glucose photoreforming for coproduction of H2 and arabinose with improved selectivity under neutral condition using carbon quantum dots (CQDs) modified TiO2 composites. We show that the conventional CQDs fabricated by a facile one-step hydrothermal process could be endowed with novel color changing property, due to the particle aggregation under the regulation of incident light. The as-fabricated CQDs/TiO2 composites with certain colored CQDs could greatly improve glucose to arabinose conversion selectivity (~75%) together with efficient hydrogen evolution (up to 2.43 mmolh−1g−1) in water. The arabinose is produced via the direct C1-C2 α-scissions mechanism with reactive oxygen species of O2− and OH, as evidenced by 13C labeled glucose and the electron spin-resonance (ESR) studies, respectively. This work not only sheds new lights on CQDs assisted photobiorefinery for biomass valorization and H2 coproduction, but also opens the door for rationale design of different colored CQDs and their potential applications for solar energy utilization in the noble-metal-free system.

Uncovering an efficient and stable photocatalytic system for seawater splitting is a highly desirable but challenging goal. Herein, Cd0.2Zn0.8S@Silicalite-1 (CZS@S-1) composites, in which CZS is embedded in the hierarchical zeolite S-1, were prepared and show remarkably high activity, stability and salt resistance in seawater.

Uronic acid in extracellular polymeric substances is a primary but often ignored factor related to the difficult hydrolysis of waste-activated sludge (WAS), with alginate as a typical polymer. Previously, we enriched alginate-degrading consortia (ADC) in batch reactors that can enhance methane production from WAS, but the enzymes and metabolic pathway are not well documented. In this work, two chemostats in series were operated to enrich ADC, in which 10 g/L alginate was wholly consumed. Based on it, the extracellular alginate lyase (∼130 kD, EC 4.2.2.3) in the cultures was identified by metaproteomic analysis. This enzyme offers a high specificity to convert alginate to disaccharides over other mentioned hydrolases. Genus Bacteroides (>60%) was revealed as the key bacterium for alginate conversion. A new Entner−Doudoroff pathway of alginate via 5-dehydro-4-deoxy-D-glucuronate (DDG) and 3-deoxy-D-glycerol-2,5-hexdiulosonate (DGH) as the intermediates to 2-keto-3-deoxy-gluconate (KDG) was constructed based on the metagenomic and metaproteomic analysis. In summary, this work documented the core enzymes and metabolic pathway for alginate degradation, which provides a good paradigm when analyzing the degrading mechanism of unacquainted substrates. The outcome will further contribute to the application of Bacteroides-dominated ADC on WAS methanogenesis in the future.

Supercapacitor-like Na-ion batteries have attracted much attention due to the high energy density of batteries and power density of capacitors. Titanium dioxide (TiO2), is a promising anode material. Its performance is however seriously hindered by its low electrical conductivity and the sluggish diffusion of sodium ions (Na+) in the TiO2 matrix. Herein, this work combines porous TiO2 nanocubes with carbon nanotubes (CNTs) to enhance the electrical conductivity and accelerate Na+ diffusivity for Na-ion batteries (NIBs). In this composite, an interwoven scaffolded TiO2/CNTs framework is formed to provide abundant channels and shorter diffusion pathways for electrons and ions. The in-situ X-ray diffraction and cyclic voltammetry confirm the low strain and superior transport kinetics in Na+ intercalation/extraction processes. In addition, the chemically bonded TiO2/CNTs hybrid provides a more feasible channel for Na+ insertion/extraction with a much lower energy barrier. Consequently, the TiO2/CNTs composite exhibits excellent electrochemical performance with a capacity of 223.4 mAh g−1 at 1 C and a capacity of 142.8 mAh g−1 at 10 C (3.35 A g−1). The work here reveals that the combination of active materials with CNTs can largely improve the utilization efficiency and enhance their sodium storage.

Lithium-sulfur (Li-S) batteries have attracted significant attention for their high specific capacity, non-toxic and harmless advantages. However, the shuttle effect limits their development. In this work, small-sized tin disulfide (SnS2) nanoparticles are embedded between interlayers of two-dimensional porous carbon nanosheets (PCNs), forming a multi-functional nanocomposite (PCN-SnS2) as a cathode carrier for Li-S batteries. The graphitized carbon nanosheets improve the overall conductivity of the electrode, and the abundant pores not only facilitate ion transfer and electrolyte permeation, but also buffer the volume change during the charge and discharge process to ensure the integrity of the electrode material. More importantly, the physical confinement of PCN, as well as the strong chemical adsorption and catalytic reaction of small SnS2 nanoparticles, synergistically reduce the shuttle effect of polysulfides. The interaction between a porous layered structure and physical-chemical confinement gives the PCN-SnS2-S electrode high electrochemical performance. Even at a high rate of 2 C, a discharge capacity of 650 mA h g−1 is maintained after 150 cycles, underscoring the positive results of SnS2 based materials for Li S batteries. The galvanostatic intermittent titration technique results further confirm that the PCN-SnS2-S electrode has a high Li+ transmission rate, which reduces the activation barrier and improves the electrochemical reaction kinetics. This work provides strong evidence that reducing the size of SnS2 nanostructures is beneficial for capturing and reacting with polysulfides to alleviate their shuttle effect in Li-S batteries.

A deep understanding of the fine structure at the atomic scale of halide perovskite materials has been limited by their sensitivity to the electron beam that is widely used for structural characterization. The sensitivity of a gamma-CsPbIBr2 perovskite thin film under electron beam irradiation is revealed by scanning transmission electron microscopy (STEM) through a universal large-range electron dose measurement, which is based on discrete single-electron events in the STEM mode. Our research indicates that the gamma-CsPbIBr2 thin film undergoes structural changes with increasing electron overall dose (e(-).A(-2)) rather than dose rate (e(-).A(-2).s(-1)), which suggests that overall dose is the key operative parameter. The electron beam-induced structural evolution of gamma-CsPbIBr2 is monitored by fine control of the electron beam dose, together with the analysis of high-resolution (S)TEM, diffraction, and energy-dispersive X-ray spectroscopy. Our results show that the gamma-CsPbIBr2 phase first forms an intermediate phase [e.g., CsPb(1-x)(IBr)((3-y))] with a superstructure of ordered vacancies in the pristine unit cell, while a fraction of Pb2+ is reduced to Pb-0. As the electron dose increases, Pb nanoparticles precipitate, while the remaining framework forms the Cs2IBr phase, accompanied by some amorphization. This work provides guidelines to minimize electron beam irradiation artifacts for atomic-resolution imaging on CsPbIBr2 thin films.

Motility is significant in organisms. Studying the influence of motility on biological processes provides a new angle in understanding the essence of life. Biomineralization is a representative process for organisms in forming functional materials. In the present study, we investigated the biomineralization of iron oxides templated by Escherichia coli (E. coli) cells under oscillation. The formation of iron oxide minerals with acicular and banded morphology was observed. The surface charge of E. coli cells contributed to the biomineralization process. The surface components of E. coli cells including lipids, carbohydrates and proteins also have roles in regulating the formation and morphology of iron oxide minerals. As-prepared mineralized iron oxide nanomaterials showed activity in photocatalytic degradation of methylene blue as well as in electrocatalytic hydrogen evolution reaction. This study is helpful not only in understanding motility in biological processes, but also in developing techniques for fabricating functional nanomaterials.

The introduction of Na+ is considered as an effective way to improve the performance of Ni-rich cathode materials. However, the direct structure–property correlation for Na+ doped NCM-based cathode materials remain unclear, due to the difficulty of local and accurate structural characterization for light elements such as Li and Na. Moreover, there is the complexity of the modeling for the whole Li ion battery (LIB) system. To tackle the above-mentioned issues, we prepared Na+-doped LiNi0.6Co0.2Mn0.2O2 (Na-NCM622) material. The crystal structure change and the lattice distortion with picometers precision of the Na+-doped material is revealed by Cs-corrected scanning transmission electron microscopy (STEM). Density functional theory (DFT) and the recently proposed electrochemical model, i.e., modified Planck-Nernst-Poisson coupled Frumkin-Butler-Volmer (MPNP-FBV), has been applied to reveal correlations between the activation energy and the charge transfer resistance at multiscale. It is shown that Na+ doping can reduce the activation energy barrier from ΔG = 1.10 eV to 1.05 eV, resulting in a reduction of the interfacial resistance from 297 Ω to 134 Ω. Consequently, the Na-NCM622 cathode delivers a superior capacity retention of 90.8 % (159 mAh.g−1) after 100 cycles compared to the pristine NCM622 (67.5 %, 108 mAh. g−1). Our results demonstrate that the kinetics of Li+ diffusion and the electrochemical reaction can be enhanced by Na+ doping the cathode material.

The biomass photorefinery provides a promising strategy for value-added chemical production from natural feedstocks. Herein, we designed and fabricated a three-dimensionally ordered macroporous (3DOM) ternary composite for the photoreforming of hemicellulose and the corresponding monosaccharides. This hierarchically porous structure was revealed to restrain the crystal growth of BiVO4 and ZnO to form nanodots and clusters, respectively. The ternary photocatalyst exhibited excellent xylose conversion (∼90%) to selectively produce formic acid (∼60% selectivity) due to the synergistic effects of light harvesting, mass diffusion, oxygen vacancies and the formed heterojunction structure. The as-fabricated photocatalyst also showed the ability to break down β-1,4-glycosidic linkages of xylan in hemicellulose from wheat straw to produce xylose and formic acid. This work demonstrates a facile pathway for lignocellulose valorization to value-added chemicals by the photorefinery strategy.

Li-Se battery is a promising energy storage candidate owing to its high theoretical volumetric capacity and safe operating condition. In this work, for the first time, we report using the whole organic Melamine-based porous polymer networks (MPNs) as a precursor to synthesize a N, O, S co-doped hierarchically porous carbon nanobelts (HPCNBs) for both Li-ion and Li-Se battery. The N, O, S co-doping resulting in the defect-rich HPCNBs provides fast transport channels for electrolyte, electrons and ions, but also effectively relieve volume change. When used for Li-ion battery, it exhibits an advanced lithium storage performance with a capacity of 345 mAh g−1 at 500 mA g−1 after 150 cycles and a superior rate capacity of 281 mAh g−1 even at 2000 mA g−1. Further density function theory calculations reveal that the carbon atoms adjacent to the doping sites are electron-rich and more effective to anchor active species in Li-Se battery. With the hierarchically porous channels and the strong dual physical–chemical confinement for Li2Se, the Se@ HPCNBs composite delivers an ultra-stable cycle performance even at 2 C after 1000 cycles. Our work here suggests that introduce of heteroatoms and defects in graphite-like anodes is an effective way to improve the electrochemical performance.

MXenes, a new family of functional two-dimensional (2D) materials, have shown great potential for an extensive variety of applications within the last decade. Atomic defects and functional groups in MXenes are known to have a tremendous influence on the functional properties. In this review, we focus on recent progress in the characterization of atomic defects and functional group chemistry in MXenes, and how to control them to directly influence various properties (e.g., electron transport, Li' adsorption, hydrogen evolution reaction (HER) activity, and magnetism) of 2D MXenes materials. Dynamic structural transformations such as oxidation and growth induced by atomic defects in MXenes are also discussed. The review thus provides perspectives on property optimization through atomic defect engineering, and bottom-up synthesis methods based on defect-assisted homoepitaxial growth of MXenes. (C) 2020 Chinese Chemical Society and Institute of Materia Medica, Chinese Academy of Medical Sciences. Published by Elsevier B.V. All rights reserved.

Hierarchical single-crystal ZSM-5 zeolites with different Si/Al ratios (Hier-ZSM-5-x, where x = 50, 100, 150 and 200) were synthesized using an ordered mesoporous carbon-silica composite as hard template. Hier-ZSM-5-x exhibits improved mass transport properties, excellent mechanical and hydrothermal stability, and higher catalytic activity than commercial bulk zeolites in the benzyl alcohol self-etherification reaction. Results show that a decrease in the Si/Al ratio in hierarchical single-crystal ZSM-5 zeolites leads to a significant increase in the acidity and the density of micropores, which increases the final catalytic conversion. The effect of porous hierarchy on the diffusion of active sites and the final catalytic activity was also studied by comparing the catalytic conversion after selectively designed poisoned acid sites. These poisoned Hier-ZSM-5-x shows much higher catalytic conversion than the poisoned commercial ZSM-5 zeolite, which indicates that the numerous intracrystalline mesopores significantly reduce the diffusion path of the reactant, leading to the faster diffusion inside the zeolite to contact with the acid sites in the micropores predominating in ZSM-5 zeolites. This study can be extended to develop a series of hierarchical single-crystal zeolites with expected catalytic performance.

Single-atom catalysts (SACs) have attracted widespread interest for many catalytic applications because of their distinguishing properties. However, general and scalable synthesis of efficient SACs remains significantly challenging, which limits their applications. Here we report an efficient and universal approach to fabricating a series of high-content metal atoms anchored into hollow nitrogen-doped graphene frameworks (M-N-Grs; M represents Fe, Co, Ni, Cu, etc.) at gram-scale. The highly compatible doped ZnO templates, acting as the dispersants of targeted metal heteroatoms, can react with the incoming gaseous organic ligands to form doped metal–organic framework thin shells, whose composition determines the heteroatom species and contents in M-N-Grs. We achieved over 1.2 atom % (5.85 wt %) metal loading content, superior oxygen reduction activity over commercial Pt/C catalyst, and a very high diffusion-limiting current (6.82 mA cm–2). Both experimental analyses and theoretical calculations reveal the oxygen reduction activity sequence of M-N-Grs. Additionally, the superior performance in Fe-N-Gr is mainly attributed to its unique electron structure, rich exposed active sites, and robust hollow framework. This synthesis strategy will stimulate the rapid development of SACs for diverse energy-related fields., An efficient and universal approach to fabricating a series of high-content metal atoms anchored into hollow nitrogen-doped graphene frameworks is developed via a nicely designed process.

We have developed a controlled-release drug carrier. Smartly controlled-release polymer nanoparticles were firstly synthesized through RAFT polymerization as the controlled-release core. The structural and particle properties of polymer nanoparticles were characterized by nuclear magnetic resonance spectroscopy (1H-NMR), scanning electron microscope (SEM) and X-ray spectroscopy (EDX). Mesoporous materials were selected as the shell materials to encapsulate the smart core as the stable shell. The mesoporous shell was characterized by transmission electron microscopy (TEM) and scanning electron microscope (SEM). All the results showed that a well-defined core-shell structure with mesoporous structure was obtained, and this controllable delivery system will have the great potential in nanomedicine.

Active crystal facets can generate special properties for various applications. Herein, we report a (001) faceted nanosheet-constructed hierarchically porous TiO2/rGO hybrid architecture with unprecedented and highly stable lithium storage performance. Density functional theory calculations show that the (001) faceted TiO2 nanosheets enable enhanced reaction kinetics by reinforcing their contact with the electrolyte and shortening the path length of Li+ diffusion and insertion-extraction. The reduced graphene oxide (rGO) nanosheets in this TiO2/rGO hybrid largely improve charge transport, while the porous hierarchy at different length scales favors continuous electrolyte permeation and accommodates volume change. This hierarchically porous TiO2/rGO hybrid anode material demonstrates an excellent reversible capacity of 250 mAh g–1 at 1 C (1 C = 335 mA g–1) at a voltage window of 1.0–3.0 V. Even after 1000 cycles at 5 C and 500 cycles at 10 C, the anode retains exceptional and stable capacities of 176 and 160 mAh g–1, respectively. Moreover, the formed Li2Ti2O4 nanodots facilitate reversed Li+ insertion-extraction during the cycling process. The above results indicate the best performance of TiO2-based materials as anodes for lithium-ion batteries reported in the literature.

Lithium-sulfur batteries with high theoretical specific capacity are quite promising in energy storage systems. The application of lithium-sulfur batteries however has mainly been hampered by the severe shuttle effect of polysulfides during the charging/discharging process. Here, we report the in situ self-assembling of ultra-thin flexible polyaniline layer decorated manganese dioxide nanoparticles (PANI-MnO2) to form a three-dimensional hierarchically porous network as a sulfur host for lithium-sulfur batteries. The hierarchically porous PANI-MnO2 network not only provides a porous structure to alleviate the volume expansion, but also offers fast channels to accelerate the transfer of active species, electrons and ions to improve the redox reaction kinetics. The as-fabricated PANI-MnO2-S electrode thus demonstrates excellent electrochemical performance, with a stable capacity up to 1195 mA h g-1 at 0.5C after 100 cycles. In particular, the hierarchically porous PANI-MnO2 network employs an extraordinary chemical process for polysulfides to form active thiosulfates, which are further converted into Li2S. This significantly suppresses the shuttle effect, thus providing the possibility for fast charging. As a result, the PANI-MnO2-S electrode exhibits a discharge capacity of 640 mA h g-1 at 2C after 500 cycles. Even at a high sulfur loading of 4.0 mg cm-2, a stable areal capacity of ∼3.12 mA h cm-2 is achieved at 1C after 200 cycles.

The development of a suitable catalytic system in the single catalyst has always been the pursuit for synthetic chemists in order to perform the traditional stepwise reactions in one-pot mode. In this work, an ultra-stable bifunctional catalyst of Pd@MIL-101-SO3H was successfully constructed and applied in the one-pot oxidation-acetalization reaction whose products have been widely utilized as fuel additives, perfumes, pharmaceuticals and polymer chemistry. The excellent catalytic performance (>99% yields), on the one hand, can be ascribed to the synergistic effects of Pd NPs with both Lewis and Bronsted acid encapsulated within a sulfonated MIL-101(Cr). On the other hand, the exceptionally high capacity of water adsorption in MIL-101(Cr) could promote the equilibrium movement via interrupting the reversible process. More importantly, Pd@MIL-101-SO3H is recyclable and can be reused for at least 8 times without sacrificing its catalytic activities. As far as we know, this is the first time that a water adsorption enhanced equilibrium movement of reversible reaction by porous catalyst to achieve high yields has been realized in Pd@MIL-101-SO3H, which may provide an absolutely new and efficient strategy especially for designing reaction-oriented catalysts.

Sodium-ion batteries (SIBs) are considered as a promising large-scale energy storage system owing to the abundant and low-cost sodium resources. However, their practical application still needs to overcome some problems like slow redox kinetics and poor capacity retention rate. Here, a high-performance ZnSe/carbon fibers (ZnSe-CFs) anode is demonstrated with high electrons/Na+ transport efficiency for sodium-ion half/full batteries by engineering ZnSe/C heterostructure. The electrochemical behavior of the ZnSe-CFs heterostructure anode is deeply studied via in situ characterizations and theoretical calculations. Phase conversion is revealed to accelerate the “Zn-escape” effect for the formation of robust solid electrolyte interphase (SEI). This leads to the ZnSe-CFs delivering a superior rate performance of 206 mAh g−1 at 1500 mA g−1 for half battery and an initial discharge capacity of 197.4 mAh g−1 at a current density of 1 A g−1 for full battery. The work here heralds a promising strategy to synthesize advanced heterostructured anodes for SIBs, and provides the guidance for a better understanding of phase conversion anodes.

Increasing the separation efficiency of photogenerated carriers and preventing the hydrogen back oxidation are two key challenges in photocatalytic hydrogen production. Herein, we report a promising PtO@Ti3C2/TiO2 photocatalyst to overcome these two challenges by in-situ growing TiO2 nanosheets on Ti3C2 MXene (to improve charge separation) and depositing PtO nanodots (to diminish hydrogen back reaction) for enhanced photocatalytic hydrogen production. Within this design principle, the photogenerated electrons and holes in the PtO@Ti3C2/TiO2 composites flow in opposite direction into PtO and Ti3C2 respectively, resulting in effective separation of the photogenerated electrons and holes. Beyond, the higher oxidation state of PtO nanodots also largely suppresses the undesirable hydrogen back oxidation reaction. Thereby the PtO@Ti3C2/TiO2 composite demonstrates remarkable hydrogen production efficiency. Our work here indicates that rational design of dual co-catalysts could not only promote the separation of photogenerated carriers for enhanced hydrogen production, but also inhibit the reverse reaction of hydrogen production.

Photocatalytic hydrogen (H 2 )production based on semiconductors is important to utilize solar light for clean energy and environment. Herein, we report a visible light responsive heterostructure, designed and constructed by molybdenum disulfide quantum dots (MoS 2 -QDs)in-situ seeds-directing growth and self-assemble of zinc indium sulfide (ZnIn 2 S 4 )nanosheet to ensure their full contact through a simple one-step solvothermal method for highly improved visible light H 2 production. The MoS 2 -QDs in-situ seeds-directing ZnIn 2 S 4 heterostructure not only builds heterojunctions between MoS 2 and ZnIn 2 S 4 to spatially separate the photogenerated electrons and holes, but also serves as the active sites trapping photogenerated electrons to facilitate H 2 evolution. As a result, MoS 2 -QDs/ZnIn 2 S 4 exhibits high photocatalytic activity for H 2 production, and the optimized 2 wt% MoS 2 -QDs/ZnIn 2 S 4 (2MoS 2 -QDs/ZnIn 2 S 4 )heterostructure exhibits the highest H 2 evolution rate of 7152 umol·h −1 ·g −1 under visible light, ∼9 times of pure ZnIn 2 S 4 . Our strategy here could shed some lights on developing noble-metal free heterostructures for highly efficient photocatalytic H 2 production.

The development of lithium-ion batteries using transition metal oxides has recently become more attractive, due to their higher specific capacities, better rate capability, and high energy densities. Herein, the in situ growth of advanced mesoporous CuO/O-doped g-C3N4 nanospheres is carried out in a two step hydrothermal process at 180 °C and annealing in air at 300 °C. When used as an anode material, the CuO/O-doped g-C3N4 nanospheres achieve a high reversible discharge specific capacity of 738 mAhg-1 and a capacity retention of ∼75.3% after 100 cycles at a current density 100 mAg-1 compared with the pure CuO (412 mAhg-1, 47%) and O-doped g-C3N4 (66 mAhg-1, 53%). Even at high current density 1 Ag-1, they exhibit a reversible discharge specific capacity of 503 mAhg-1 and capacity retention ∼80% over 500 cycles. The excellent electrochemical performance of the CuO/O-doped g-C3N4 nanocomposite is attributed to the following factors: (I) the in situ growing CuO/O-doped g-C3N4 avoids CuO nanoparticle aggregation, leading to the improved lithium ion transfer and electrolyte penetration inside the CuO/O-doped g-C3N4 anode, thus promoting the utilization of CuO; (II) the porous structure provides efficient space for Li+ transfer during the insertion/extraction process to avoid large volume changes; (III) the O-doping g-C3N4 decreases its band gap, ensuring the increased electrical conductivity of CuO/O-doped g-C3N4; and (IV) the strong interaction between CuO and O-doped g-C3N4 ensures the stability of the structure during cycling.

Ternary zinc oxide/bismuth vanadate/three-dimensional ordered macroporous titanium dioxide (ZnO/BiVO4/3DOM TiO2) heterojuncted nanocomposites with cascade electronic band structures were successfully designed and synthesized for visible light photodegradation of two different molecules: Rhodamine B (RhB) and Tartrazine. The photocatalytic active species have been investigated by using electron scavenger (AgNO3) and hole scavenger (Triethanolamine: TEOA). The band edge positions of each component in tenary nanocomposites have been measured by using photoelectrochemical Mott-Schottky method and valence band XPS (VB-XPS) spectroscopy. Within the heterojunction, charges are favorably and spatially separated through the gradient potential at the interfaces. This largely suppresses the recombination of photogenerated electrons and holes. Furthermore, 3DOM inverse opal structure is beneficial for high diffusion efficiency and highly accessible surface area of reactants and light and multiple scattering for light harvesting. Consequently, these heterojuncted nanocomposites exhibit highly enhanced photocatalytic performance compared with pure BiVO4 nanostructure, and binary BiVO4/3DOM TiO2, ZnO/BiVO4 nanocomposites. A detailed mechanism of charge transfer is proposed for these ternary ZnO/BiVO4/3DOM TiO2 nanocomposites on the basis of a large series of spectroscopic and photocatalytic results. Our work demonstrates clearly that coupling multicomponent semiconductors with different energy levels of conduction and valence bands can significantly increase the photogenerated charge carriers through the efficient charge separation across their multiple interfaces. This work gives some new ideas on developing new visible light responsive nanocomposites for highly efficient solar energy utilization.

Core-shell structured Co@Silica@meso-Silica nanoparticles have been synthesized via a layer-by-layer approach. The magnetic cobalt core makes the nanoparticles easy to separate with an external magnetic field. The inner dense silica layer prevents the Co from oxidation and leaching. The outer mesoporous silica presents high surface area and pore volume, endowing the material with superior adsorption properties of organic molecules. The core-shell structure prevents the direct contact of cobalt with living cells, thus enhancing the biocompatibility remarkably. This dual encapsulation provides a golden opportunity to the nanocarrier design with easy magnetic separation, high drug loading, and high biocompatibility.

The lithium-selenium (Li-Se) battery has attracted growing interest recently due to its high energy density and theoretical capacity. However, the shuttle effect and volume change during cycling severely hinder its further application. In this work, we report a metal-organic framework (MOF)-derived nitrogen-doped core-shell hierarchical porous carbon (N-CSHPC) with interconnected meso/micropores to effectively confine Se for high-performance Li-Se batteries. The micropores were located at the ZIF-8-derived core and the ZIF-67-derived shell, while mesopores appeared at the core-shell interface after the pyrolysis of the core-shell ZIF-8@ZIF-67 precursor. Such a special hierarchical porous structure effectively confined selenium and polyselenides to prevent their dissolution from the pores and also alleviated the volume change. In particular, in situ nitrogen doping, which afforded N-CSHPC, not only improved the electrical conductivity of Se but also provided strong chemical adsorption on Li 2 Se, as confirmed by density functional theory calculations. On the basis of dual-physical confinement and strong chemisorption, Se/N-CSHPC-II (molar ratio of Co source to Zn source of 1.0 in the core-shell ZIF-8@ZIF-67 precursor) exhibited reversible capacities of up to 555 mA h g -1 after 150 cycles at 0.2 C and 462 mA h g -1 after 200 cycles at 0.5 C and even a discharge capacity of 432 mA h g -1 after 200 cycles at 1 C. Our demonstration here suggests that the carefully designed Se/C composite can improve the reversible capacity and cycling stability of Se cathodes for Li-Se batteries.

The shuttling of polysulfides with sluggish redox kinetics has severely retarded the advancement of lithium–sulfur (Li–S) batteries. In this work oxygen-deficient titanium dioxide (TiO2) has been investigated as a novel functional host for Li–S batteries. Experimental and first-principles density functional theory (DFT) studies reveal that oxygen vacancies help to reduce polysulfide shuttling and catalyze the redox kinetics of sulfur/polysulfides during cycling. Consequently, the resulting TiO2/S composite cathode manifests superior electrochemical properties in terms of high capacity (1472 mA h g−1 at 0.2C), outstanding rate capability (571 mA h g−1 at 2C), and excellent cycling properties (900 mA h g−1 over 100 cycles at 0.2C). The present strategy offers a viable way through vacancy engineering for the design and optimization of high-performance electrodes for advanced Li–S batteries and other electrochemical devices.

As a typical two-dimensional (2D) metal chalcogenides and visible-light responsive semiconductor, zinc indium sulfide (ZnIn2S4) has attracted much attention in photocatalysis. However, the high recombination rate of photogenerated electrons and holes seriously limits its performance for hydrogen production. In this work, we report in-situ photodeposition of Ni clusters in hierarchical ZnIn2S4 nanoflowers (Ni/ZnIn2S4) to achieve unprecedented photocatalytic hydrogen production. The Ni clusters not only provide plenty of active sites for reactions as evidenced by in-situ photoluminescence measurement, but also effectively accelerate the separation and migration of the photogenerated electrons and holes in ZnIn2S4. Consequently, the Ni/ZnIn2S4 composites exhibit good stability and reusability with highly enhanced visible-light hydrogen production. In particular, the best Ni/ZnIn2S4 photocatalyst exhibits an unprecedented hydrogen production rate of 22.2 mmol·h−1·g−1, 10.6 times that of the pure ZnIn2S4 (2.1 mmol·h−1·g−1). And its apparent quantum yield (AQY) is as high as 56.14% under 450 nm monochromatic light. Our work here suggests that depositing non-precious Ni clusters in ZnIn2S4 is quite promising for the potential practical photocatalysis in solar energy conversion.

Like nanomaterials, bacteria have been unknowingly used for centuries. They hold significant economic potential for fuel and medicinal compound production. Their full exploitation, however, is impeded by low biological activity and stability in industrial reactors. Though cellular encapsulation addresses these limitations, cell survival is usually compromised due to shell-to-cell contacts and low permeability. Here, we report ordered packing of silica nanocolloids with organized, uniform and tunable nanoporosities for single cyanobacterium nanoencapsulation using protamine as an electrostatic template. A space between the capsule shell and the cell is created by controlled internalization of protamine, resulting in a highly ordered porous shell-void-cell structure formation. These unique yolk-shell nanostructures provide long-term cell viability with superior photosynthetic activities and resistance in harsh environments. In addition, engineering the colloidal packing allows tunable shell-pore diameter for size-dependent permeability and introduction of new functionalities for specific molecular recognition. Our strategy could significantly enhance the activity and stability of cyanobacteria for various nanobiotechnological applications., Single-cell yolk-shell nanoencapsulation endows living cells with a hierarchical ordered porous structure, significantly enhancing biological activity, stability, molecular recognition and resistance to harsh environment for various nanobiotechnological functionalisation and applications.

Two dimensional (2D) nanostructures are promising to provide a new hierarchical architecture for transition metal oxides (TMOs) with outstanding lithium storage. In this work, we grew ordered CuO nanorods on 2D Cu/g-C3N4 nanosheets to form the hierarchical CuO@Cu/g-C3N4 nanorods film as freestanding anode for advanced lithium storage. This assembled freestanding film demonstrates a high discharge specific capacity at 726 mAhg−1 after 200 cycles at 0.1C and a discharge specific capacity of 457 mAhg−1 after 625 cycles at 1C, among the best performance in CuO and CuO based nanostructures for lithium storage. Its outstanding stability and cyclic performance are ascribed to the following aspects during the reaction process: (i) the unique 2D nanostructure provides large exposed area for Li+ insertion, (ii) the ordered CuO nanorods provide interior spaces to accommodate the volume change and offer more paths for charges and Li+ transfer, (iii) the existence of Cu nanosheets increases the electrons transport and (iv) the porous g-C3N4 nanosheets endow the prepared structure more active sites for facilitating Li+ transport and accommodating volume change. Our strategy on growing ordered nanostructures on 2D nanosheets will be an effective way to modify TMOs for advanced lithium-ion batteries.

Summary Photocatalytic transformation of biomass into value-added chemicals coupled with co-production of hydrogen provides an explicit route to trap sunlight into the chemical bonds. Here, we demonstrate a rational design of Zn1-xCdxS solid solution homojunction photocatalyst with a pseudo-periodic cubic zinc blende (ZB) and hexagonal wurtzite (WZ) structure for efficient glucose conversion to simultaneously produce hydrogen and lactic acid. The optimized Zn0.6Cd0.4S catalyst consists of a twinning superlattice, has a tuned bandgap, and displays excellent efficiency with respect to hydrogen generation (690 ± 27.6 μmol·h−1·gcat.−1), glucose conversion (~90%), and lactic acid selectivity (~87%) without any co-catalyst under visible light irradiation. The periodic WZ/ZB phase in twinning superlattice facilitates better charge separation, while superoxide radical (⋅O2-) and photogenerated holes drive the glucose transformation and water oxidation reactions, respectively. This work demonstrates that rational photocatalyst design could realize an efficient and concomitant production of hydrogen and value-added chemicals from glucose photocatalysis., Graphical Abstract, Highlights • Zn1-xCdxS ZB-WZ homojunction was designed to improve charge separation efficiency • Bandgap engineering improved the hydrogen production from glucose photoreforming • Optimized Zn0.6Cd0.4S ZB-WZ exhibited high lactic acid yield and selectivity • Rational photocatalyst design realizes biomass valorization and H2 coproduction, Chemistry; Catalysis; Engineering; Materials Science

Photoreforming of lignocellulosic biomass is an emerging and sustainable strategy for coproduction of high-value chemicals and fuels. Challenges remain to selectively convert biomass macromolecular via sunlight-driven photocatalysis due to limited mass diffusion, insufficient charge separation and lack of mechanistic understanding. Herein, inspired by natural photosynthesis, we demonstrate a hierarchically threedimensionally ordered macroporous (3DOM) TiO2-Au-CdS Z-scheme heterojunction photocatalyst to improve mass diffusion, charge separation and light absorption efficiency. We show the photocatalytic cleavage pathway of cellulose β-1,4-glycosidic linkage (the most abundant linkage within biomass) over 3DOM TiO2-Au-CdS heterojunction by using cellobiose as a model component. Similar to the oxidative enzymes in nature, the all-solid-state Z-scheme photocatalyst demonstrates oxygen insertion at C1 position followed by the elimination reaction, which oxidatively cleaves the β-1,4-glycosidic bond and results in gluconic acid and glucose generation. In presence of oxygen, glucose is further oxidized into gluconic acid which is subsequently oxidized or decarboxylated into glucaric acid or arabinose. The present study may serve as a framework to rationally design photocatalyst to reveal mechanistic understanding of biomass photoreforming towards high-value fuels and chemical feedstocks.

Summary Efficient electrocatalyst toward hydrogen evolution/oxidation reactions (HER/HOR) and oxygen reduction reaction (ORR) is desirable for water splitting, fuel cells, etc. Herein, we report an advanced platinum phosphide (PtP2) material with only 3.5 wt % Pt loading embedded in phosphorus and nitrogen dual-doped carbon (PNC) layer (PtP2@PNC). The obtained catalyst exhibits robust HER, HOR, and ORR performance. For the HER, a much low overpotential of 8 mV is required to achieve the current density of 10 mA cm−2 compared with Pt/C (22 mV). For the HOR, its mass activity (MA) at an overpotential of 40 mV is 2.3-fold over that of the Pt/C catalyst. Interestingly, PtP2@PNC also shows exceptional ORR MA which is 2.6 times higher than that of Pt/C and has robust stability in alkaline solutions. Undoubtedly, this work reveals that PtP2@PNC can be employed as nanocatalysts with an impressive catalytic activity and stability for broad applications in electrocatalysis., Graphical Abstract, Highlights • PtP2@PNC is synthesized under ambient pressure and moderate temperatures • The formed PtP2@PNC exhibits outstanding performance toward HER, HOR, and ORR • The synergistic effect between PtP2 and PNC is responsible for the high activity, Chemistry; Electrochemistry; Electrochemical Energy Conversion; Materials Science; Energy Materials

TiO2 hierarchical microsphere assembled from anatase TiO2 nanosheets has been successfully prepared and exhibited excellent catalytic activities of H2 production and benzyl alcohol selective oxidized to benzaldehyde. These enhanced photoactivity can be mainly ascribed to the charge separation promoted by the surface F and nanosheet units, enhancement of substrate molecular transport profited from the hierarchical structure.

It is desirable to control volatile fatty acids (VFAs) recovery from waste activated sludge (WAS) while avoiding the release of N and P. Structural extracellular polymeric substances (St-EPS), with typical components of alginate and polygalacturonic acid, resist the biodegradation of extracellular polymeric substances (EPS) in WAS. Previously, we purposely enriched an alginate-degrading consortium (ADC), but, both controlling VFAs production and cell integrity after dosing with ADC were not investigated. In this work, ADC with a high percentage of the genus Bacteroides (~67%) was further enriched with alginate utilization above 95%. The St-EPS content in WAS was 109.7 ± 3.3 mg/g-VSS, accounting for 31% of EPS. After dosing ADC in the WAS, the main metabolites were acetate (1.6 g/L) and propionate (0.7 g/L), the hydrolysis efficiency was increased to 38%, and the acidification efficiency was increased to 72%. Cell integrity was maintained during WAS fermentation by dosing with ADC according to no P release and unchanged lactate dehydrogenase activity. VFA production was mainly from the EPS, and protein degradation in EPS resulted in low N release (e.g., 212 mg/L from casein and no P release). Consequently, ADC doing offers the advantages of controlling VFAs production from EPS while maintaining cell integrity.

The refractory organics released from waste activated sludge (WAS) are unwanted produced in thermal-alkaline pretreatment, which are not well documented. In this study, we refer to them as melanoidins products (MPs) with characteristics of high molecular weight and inhibition to microbes. The results showed that these MPs from thermal-alkaline (80 °C and pH 10) pretreatment of WAS were identified with a broad molecular weight (> 1000 Da). Dark-colored MPs were further verified from glucose and tryptophan as the model components, with values of UV280 and UV420 increasing. The produced MPs with a molecular weight of 1220, 6835, and even 21,200,000 Da were confirmed by SEC-HPLC. Unexpectedly, MPs were found to be electroactive with higher redox peak values than that of humic acids, which were almost not degraded by anaerobes as revealed by SEC-HPLC and 3D-EEM spectra. For the first time, the results demonstrated that MPs delayed volatile fatty acids production and reduced the methane yield (22–26% lower), which was likely attributed to the toxicity and/or electrons competition with anaerobes such as Methanosaeta. Thus, it is clear that MPs negatively impact anaerobic digestion after thermal-alkaline pretreatment, which shall be re-evaluated to minimize MPs when producing biochemicals from WAS.

We report three types of conducting polymers (CPs), polyaniline (PANI), polypyrrole (PPY) and poly (3,4-ethylenedioxythiophene) (PEDOT) to modify the surface of the CdS nanorods to probe their photocorrosion inhibition and photocatalytic hydrogen production. Various characterizations, such as high resolution transmission electron microscopy (HRTEM), X-ray photoelectron spectroscopy (XPS), cyclic voltammetry (CV) and density function theory (DFT) calculations have been conducted to reveal the intrinsic structure of the as-constructed CPs@CdS (@ means CPs at the surface of CdS) core-shell nanorods. The results show that the PANI and PPY shells with abundant N and C atoms can significantly enhance the binding energy of Cd and S atoms on the surface of the CdS nanorods. However, there is no obvious enhancement of binding energy at the interface of the PEDOT shell and the CdS nanorods core. Therefore, PANI@CdS and PPY@CdS possess stronger driving force than PEDOT@CdS to inject the photogenerated holes in conducting polymer shells. As a result, the polyaniline (PANI) modified PANI@CdS core-shell nanorods demonstrate the most effectively enhanced hydrogen production rate of ∼9.7 mmol h−1 g−1 and effective photocorrosion inhibition in 30 h without deactivation under visible-light irradiation. The hydrogen production performance of PPY@CdS is not effectively promoted owing to the weak transmittance of light for the PPY shell. The PEDOT shell cannot improve the hydrogen production and stability property of the CdS nanorods. This work could shed some light on conducting polymers modifying metal sulfides nanostructures that is of inconceivable significance for effective photocorrosion inhibition and highly enhanced photocatalytic activities.

Highly dispersed PtPd bimetallic nanocrystals with enhanced catalytic activity and stability were prepared by adjusting the interfacial wettability of the reaction solution on a commercial carbon support. This approach holds great promise for the development of high-performance and low-cost catalysts for practical applications.

The slow photon effect, a structural effect of photonic crystal photocatalyst, is very efficient in the enhancement of photocatalytic reactions. However, slow photons in powdered photonic crystal photocatalyst have rarely been discussed because they are usually randomly oriented when the photocatalytic reaction happens in solution under constant stirring. In this work, for the first time we design a gradient ternary TiO2-Au-CdS photonic crystal based on three-dimensionally ordered macroporous (3DOM) TiO2 as skeleton, Au as electron transfer medium and CdS as active material for photocatalytic H2 production under visible-light. As a result, this gradient ternary photocatalyst is favorable to simultaneously enhance light absorption, extend the light responsive region and reduce the recombination rate of the charge carriers. In particular, we found that slow photons at blue-edge exhibit much higher photocatalytic activity than that at red-edge. The photonic crystal photocatalyst with a macropore size of 250 nm exhibits the highest visible-light H2 production rate of 3.50 mmolh−1g−1 due to the slow photon energy at the blue-edge to significantly enhance the incident photons utilization. This work verifies that slow photons at the blue-edge can largely enhance light harvesting and sheds a light on designing the powdered photonic crystal photocatalyst to promote the photocatalytic H2 production via slow photon effect.

Sodium-selenium (Na-Se) batteries are a promising substitute for traditional Li-ion batteries due to their high theoretical volumetric capacity (∼3260 mA h cm -3 ). However, shuttle effects and large volume changes still limit their practical applications. Herein, we embed Se clusters in nitrogen-doped hierarchically radial-structured microporous carbon (N-HRMC) derived from a zinc-glutamate metal-organic framework (MOF) for advanced sodium storage. In this carbon-based composite, the micropores and the C-Se and C-O-Se bonds in N-HRMC effectively confine the Se clusters and Na 2 Se during the discharge-charge process. The nitrogen doping in N-HRMC strongly enhances the electrical conductivity of Se and chemical adsorption on Na 2 Se. In particular, density functional theory (DFT) calculations demonstrate that pyridinic-N atoms provide much more chemical adsorption of Na 2 Se than graphitic-N and pyrrolic-N atoms. Consequently, the cathode with Se clusters embedded in N-HRMC deliver a capacity of 612 mA h g -1 after 200 cycles at 0.2C, with cycling stability for >500 cycles and a capacity retention of ∼100% from the 20 th cycle at 0.5C, representing one of the best reported results for Na-Se batteries. Our work here suggests that embedding Se clusters in nitrogen-doped hierarchically structured microporous carbon systems presents an attractive strategy to enhance the capacity and rate capability of Na-Se batteries.

Hitherto, developing an economical and stable high-activity bifunctional Pt catalyst for oxygen reduction reaction (ORR) and hydrogen evolution reaction (HER) becomes necessary for fuel cells and regeneration fuel cell system. However, how to uniformly disperse and firmly fix Pt nanoparticles (NPs) on carbon support with optimal particle size for catalysis is still a big challenge. Herein, by taking advantage of the isolating effect of the cobalt (Co) single atom site to Pt, strong interaction between Co single atoms and Pt, and the confinement of the porous carbon matrix derived metal organic frameworks, we successfully evenly immobilize Pt NPs on ZnCo-ZIF originated porous nitrogen-doped carbon matrix with rich cobalt single atoms (Co SAs-ZIF-NC) as multiple active sites. Compared with the commercial Pt/C catalyst, Pt@Co SAs-ZIF-NC, with ultralow Pt loading and ideal particle size, not only increases the active center, but also promotes the catalysis kinetics, greatly improving the ORR and HER catalytic activity. Under acidic conditions, its half-wave potential (0.917 V) is superior to commercial Pt/C (0.868 V), and the mass activity (0.48 A per mgPt) at 0.9 V is 3 times that of Pt/C (0.16 A per mgPt), surpassing the U.S. DOE target of 0.44 A per mgPt. Besides, it also shows outstanding HER performance. At 20 and 30 mV, its mass activity is even 4.5 and 13.6 times that of Pt/C. When further employed for HER in seawater, its mass activity is about 4 times as high as that of Pt/C, demonstrating the great potential applications.

Lithium-selenium (Li-Se) batteries have attracted increasing attentions in recent years because of their high energy density and theoretical capacity. One of the keys that influences the cycle stability of Se cathode is the formation of a stable cathode electrolyte interphase (CEI) film between the cathode material and electrolyte. In this work, we report utilizing tris(trimethylsilyl) borate (TMSB) as electrolyte additive to promote the formation of stable CEI film for enhanced Li-Se battery. The TMSB containing electron-deficient boron atoms easily adsorb electron-rich F− and PFx− to form polyanionic groups, which suppress the formation of insulating LiF in the CEI film, promoting the conductivity and stability of the cathode. Furthermore, the TMSB adsorbing PFx− releases more active Li+ for reaction to improve the capacity. These largely improve the compatibility of the electrolyte and the electrode material interface, significantly reducing the interface impedance and increasing the rate capability. As the result, the system with 1 wt% TMSB exhibits a high specific discharge capacity of 462 mA h g –1 at 1 C after 500 cycles, showing 130% improvement for the cathode without TMSB. Our work here confirms that TMSB as electrolyte additive can effectively improve the electrochemical performance of Li-Se batteries.

In-situ fabrication of palladium(0) nanoparticles inside zeolitic imidazolate frameworks (ZIF-8) has been established via one-step facile spray-dry technique. Crystal structures and morphologies of the Pd@ZIF-8 samples are investigated by powder XRD, TEM, SAED, STEM, and EDX techniques. High angle annular dark field scanning transmission electron microscopy (HAAD-STEM) and 3D tomographic analysis confirm the presence of palladium nanoparticles inside the ZIF-8 structure. The porosity, surface area and N-2 physisorption properties are evaluated for Pd@ZIF-8 with various palladium contents. Furthermore, Pd@ZIF-8 samples are effectively applied as heterogeneous catalysts in alkenes hydrogenation. This straightforward method is able to speed up the synthesis of encapsulation of metal nanoparticles in metal organic frameworks. (C) 2017 Elsevier B.V. All rights reserved.

Nanostructured coreshell microspheres with a rough rutile core and a thin anatase shell are synthesized via a one-step heterogeneous templated hydrolysis process of TiCl4 vapor on the aerosol waterair interface. The rutile-in-anatase coreshell structure has been evidenced by different electron microscopy techniques, including electron energy-loss spectroscopy and 3D electron tomography. A new mechanism for the formation of a crystalline rutile core inside the anatase shell is proposed based on a statistical evaluation of a large number of electron microscopy data. We found that the control over the TiCl4 vapor pressure, the ratio between TiCl4 and H2O aerosol, and the reaction conditions plays a crucial role in the formation of the coreshell morphology and increases the yield of nanostructured microspheres.

Our whole-cell biocatalyst with a polydopamine nanocoating shows high catalytic activity (5 times better productivity than the native cell) and reusability (84% of the initial yield after 5 batches, 8 times higher than the native cell) in asymmetric reduction. It also integrates with titania, silica, and magnetic nanoparticles for multi-functionalization.

The development of a stable, efficient and economic catalyst for hydrogen evolution reaction (HER) of water splitting is one of the most hopeful approaches to confront the environmental and energy crisis. A two-step method is employed to obtain metal clusters (Ru, Pt, Pd etc.) combining single cobalt atoms anchored on nitrogen-doped carbon (Ru/Pt/Pd@Co-SAs/N-C). Based on the synergistic effect between Ru clusters and single cobalt atoms, Ru@Co-SAs/N-C exhibits an outstanding HER electrocatalytic activity. Specifically, Ru@Co-SAs/N-C only needs 7 mV overpotential at 10 mA cm-2 in 1 M KOH solution, which is much better than commercial 20 wt% Pt/C (40 mV) catalyst. Density functional theory (DFT) calculations further reveal the synergy effect between surface Ru nanoclusters and Co-SAs/N-C toward hydrogen adsorption for HER. Additionally, Ru@Co-SAs/N-C also exhibits excellent catalytic ability and durability under acidic and neutral media. The present study opens a new avenue towards the design of metal clusters/single cobalt atoms heterostructures with outstanding performance toward HER and beyond.

2D ternary systems provide another degree of freedom of tuning physical properties through stoichiometry variation. However, the controllable growth of 2D ternary materials remains a huge challenge that hinders their practical applications. Here, for the first time, by using a gallium/indium liquid alloy as the precursor, the synthesis of high-quality 2D ternary Ga2In4S9 flakes of only a few atomic layers thick (approximate to 2.4 nm for the thinnest samples) through chemical vapor deposition is realized. Their UV-light-sensing applications are explored systematically. Photodetectors based on the Ga2In4S9 flakes display outstanding UV detection ability (R-lambda = 111.9 A W-1, external quantum efficiency = 3.85 x 10(4)%, and D* = 2.25 x 10(11) Jones@360 nm) with a fast response speed (tau(ring) approximate to 40 ms and tau(decay) approximate to 50 ms). In addition, Ga2In4S9-based phototransistors exhibit a responsivity of approximate to 10(4) A W-1@360 nm above the critical back-gate bias of approximate to 0 V. The use of the liquid alloy for synthesizing ultrathin 2D Ga2In4S9 nanostructures may offer great opportunities for designing novel 2D optoelectronic materials to achieve optimal device performance.

Because of high electrocatalytic activity, Pt based metal nanospheres (NSs) have attracted a lot of attention. Hence, multi-particle nano-single crystal coalesced PtCu NSs are designed and successfully synthesized by a cost-effective aqueous solution method. The formed PtCu NS catalyst exhibits a superior hydrogen evolution reaction (HER) electrocatalytic activity with an ultralow onset potential of 18 mV at the current density of 2 mA/cm(2) and high mass activity of 1.08 A/mg(pt) (7.2 times higher than that of commercial Pt/C catalysts). Also, it shows an enhancement of 3.2 and 2.7 times in the mass and specific activities toward oxygen reduction reaction (ORR) compared to that of Pt/C. Moreover, it possesses an excellent catalytic durability for both ORR and HER. Even after 10,000 cycles, its ORR mass activity retains 87% of its initial value. The density functional theory (DFT) calculations demonstrate that by introducing Cu atoms into the Pt lattice, a downshift of the D-band center and favorable hydrogen adsorption free energy of approaching to zero (Delta G) occur, indicating the increased electrocatalytic activity of Pt electrocatalysts. (C) 2019 Elsevier Inc. All rights reserved.