查看更多>>摘要：Developing highly active and robust oxygen evolution reaction(OER)electrocatalysts is still a critical challenge for water electrolyzers and metal-air batteries.Realizing the dynamic evolution of the intermediate and charge transfer during OER and developing a clear OER mechanism is crucial to design high-performance OER catalysts.Recently in Nature,Xue and colleagues revealed a new OER mechanism,coupled oxygen evolution mechanism(COM),which involves a switchable metal and oxygen redox under light irradiation in nickel oxyhydroxide-based materials.This newly developed mechanism requires a reversible geometric conversion between octahedron(NiO6)and square planar(NiO4)to achieve electronic states with both"metal redox"and"oxygen redox"during OER.The asymmetric structure endows NR-NiOOH with a nonoverlapping region between the dz2 orbitals and a1g*bands,which facilitate the geometric conversion and enact the COM pathway.As a result,NR-NiOOH exhibited better OER activity and stability than the traditional NiOOH.
查看更多>>摘要：Harvesting solar energy to drive the semiconductor photocatalysis offers a promising tactic to address ever-growing challenges of both energy shortage and environmental pollution.Design and synthesis of nano-heterostructure photocatalysts with controllable components and morphologies are the key factors for achieving highly efficient photocatalytic processes.One-dimensional(1D)semiconductor nanofibers produced by electrospinning possess a large ratio of length to diameter,high ratio of surface to volume,small grain sizes,and high porosity,which are ideally suited for photocatalytic reactions from the viewpoint of structure advantage.After the secondary treatment of these nanofibers through the solvothermal,gas reduction,in situ doping,or assembly methods,the multi-component nanofibers with hierarchical nano-heterostructures can be obtained to further enhance their light absorption and charge carrier separation during the photocatalytic processes.In recent years,the electrospun semiconductor-based nano-heterostructures have become a"hot topic"in the fields of photocatalytic energy conversion and environmental remediation.This review article summarizes the recent progress in electrospinning synthesis of various kinds of high-performance semiconductor-based nano-heterostructure photocatalysts for H2 production,CO2 reduction,and decomposition of pollutants.The future perspectives of these materials are also discussed.
查看更多>>摘要：The properties of non-oxide materials are continuously revealed,and their applications in the fields of ceramics,energy,and catalysis are increasingly extensive.Regardless of the traditional binary materials or the MAX phases,the preparation methods,which are environmentally friendly,efficient,economical,and easy to scale-up,have always been the focus of attention.Molten salt synthesis has demonstrated unparalleled advantages in achieving non-oxide materials.In addition,with the development of the process in molten salt synthesis,it also shows great potential in scale-up production.In this review,the recent progress of molten salt synthesis in the preparation of binary non-oxide and MAX phase is reviewed,as well as some novel processes.The reaction mechanisms and the influence of synthetic conditions for certain materials are discussed in detail.The paper is finalized with the discussion of the application prospect and future research trends of molten salt synthesis in non-oxide materials.
查看更多>>摘要：Solid-state electrolytes have attracted considerable attention in new energy-related devices due to their high safety and broad application platform.Polyoxometalates(POMs)are a kind of molecular-level cluster compounds with unique structures.In recent years,owing to their abundant physicochemical properties(including high ionic conductivity and reversible redox activity),POMs have shown great potential in becoming a new generation of solid-state electrolytes.In this review,an overview is investigated about how POMs have evolved as ion-conducting materials from basic research to novel solid-state electrolytes in energy devices.First,some expressive POM-based ion-conducting materials in recent years are introduced and classified,mainly inspecting their structural and functional relationship.After that,it is further focused on the application of these ion-conducting electrolytes in the fields of proton exchange membranes,supercapacitors,and ion batteries.In addition,some properties of POMs(such as inherent dimension,capable of forming stable hydrogen bonds,and reversible bonding to water molecules)enable these functional POM-based electrolytes to be employed in innovative applications such as ion selection,humidity sensing,and smart materials.Finally,some fundamental recommendations are given on the current opportunities and challenges of POM-based ion-conducting electrolytes.
查看更多>>摘要：The ever-growing pursuit of high energy density batteries has triggered extensive efforts toward developing alkali metal(Li,Na,and K)battery(AMB)technologies owing to high theoretical capacities and low redox potentials of metallic anodes.Typically,for new battery systems,the electrolyte design is critical for realizing the battery electrochemistry of AMBs.Conventional electrolytes in alkali ion batteries are generally unsuitable for sustaining the stability owing to the hyper-reactivity and dendritic growth of alkali metals.In this review,we begin with the fundamentals of AMB electrolytes.Recent advancements in concentrated and fluorinated electrolytes,as well as functional electrolyte additives for boosting the stability of Li metal batteries,are summarized and discussed with a special focus on structure-composition-performance relationships.We then delve into the electrolyte formulations for Na-and K metal batteries,including those in which Na/K do not adhere to the Li-inherited paradigms.Finally,the challenges and the future research needs in advanced electrolytes for AMB are highlighted.This comprehensive review sheds light on the principles for the rational design of promising electrolytes and offers new inspirations for developing stable AMBs with high performance.
查看更多>>摘要：Metal nanoparticles and metal oxides promisingly provide different catalytic active sites at their interfaces.Constructing high-density interfaces is essential to maximize synergies.Herein,a Cu-Co3O4 nanoparticles interfacial structure produced via pyrolysis and moderate oxidation from metal-organic frameworks has been designed to boost the intrinsic activity.The Cu-Co3O4 nanoparticles composites exhibit a turnover frequency of 57.5 min-1 for ammonia borane hydrolysis,far higher than those of monometallic Cu and Co3O4 nanoparticles,showing the synergistic effect of Cu and Co3O4 nanoparticles at their interface.Density functional theory calculations and in situ Raman spectroscopy reveal the catalytic mechanism of dual active sites,in which Co3O4 nanoparticles at Cu-Co3O4 interface efficiently bind and activate water molecules and Cu nanoparticles easily activate NH3BH3 molecules.This study opens up a new pathway for achieving high-efficiency noble metal-free catalysts for hydrogen generation and other heterogeneous catalysis.
查看更多>>摘要：Graphitic carbon nitride(g-C3N4)is viewed as a promising visible-light photocatalyst for industrialization due to its low processing temperature and high chemical stability.However,serious charge recombination caused by incomplete polymerization during direct calcination of nitrogen-rich precursors significantly limits its photocatalytic performances.To boost charge separation,herein,we propose a rational strategy by constructing a crystalline g-C3N4/g-C3N4-xSx isotype heterostructure through the molten salt method.Theoretical calculation reveals that apparent charge-transfer channels are formed between g-C3N4 and S-doped g-C3N4 layers in the heterostructure.Owing to high crystallinity for decreasing charge recombination and isotype heterostructure for efficient charge transfer,the as-prepared g-C3N4/g-C3N4-xSx showed remarkable photocatalytic performances with the hydrogen production rate elevated by up to 12.3 times of its singular components.Another novelty of this work is we investigated for the first time the piezocatalytic activity of crystalline g-C3N4 by characterizing its performance for H2O2 generation and KMnO4 reduction.Strikingly,its superior piezocatalytic performance over components can be further improved by NaBH4 treatment,which is uncovered to enhance the asymmetric structure of crystalline g-C3N4 by introducing extra cyano groups and removing partial NHx species in its tri-s-triazine layer structure.This work opens up new strategies for the design of highly efficient polymeric photocatalysts and highlights the piezocatalytic studies of g-C3N4.
查看更多>>摘要：Regulating the selectivity toward a target hydrocarbon product is still the focus of CO2 electroreduction.Here,we discover that the original surface Cu species in Cu gas-diffusion electrodes plays a more important role than the surface roughness,local pH,and facet in governing the selectivity toward C1 or C2 hydrocarbons.The selectivity toward C2H4 progressively increases,while CH4 decreases steadily upon lowering the Cu oxidation species fraction.At a relatively low electrodeposition voltage of 1.5 V,the Cu gas-diffusion electrode with the highest Cuδ+/Cu0 ratio favors the pathways of*CO hydrogenation to form CH4 with maximum Faradaic efficiency of 65.4％and partial current density of 228 mA cm-2 at-0.83 V vs RHE.At 2.0 V,the Cu gas-diffusion electrode with the lowest Cuδ+/Cu0 ratio prefers C-C coupling to form C2+products with Faradaic efficiency topping 80.1％at-0.75 V vs RHE,where the Faradaic efficiency of C2H4 accounts for 46.4％and the partial current density of C2H4 achieves 279 mA cm-2.This work demonstrates that the selectivity from CH4 to C2H4 is switchable by tuning surface Cu species composition of Cu gas-diffusion electrodes.
查看更多>>摘要：Solid/solid interface is the major challenge for high-performance solid-state batteries.Solid electrolytes(SEs)play a crucial role in the fabrication of effective interfaces in solid-state batteries.Herein,the electrolyte distribution with varied particle sizes is tuned to construct solid-state batteries with excellent performance at different operating temperatures.Solid-state batteries with the configuration S/L(small-sized SE in composite cathode and large-sized SE in electrolyte layer)show the best performance at room temperature(168 mA h g-1 at 0.2 C,retention of 99％,100 cycles)and-20 ℃(89 mA h g-1 at 0.05 C),while the configuration S/S displays better performance at elevated temperature.The superior performance of S/L battery is associated with faster lithium-ion dynamics due to the better solid/solid interface between active materials and electrolytes.Moreover,the inferior performance at 60 ℃ is caused by the formation of voids and cracks in the electrolyte layer during cycling.In contrast,the S/S battery delivers superior performance at elevated operating temperature because of the integrated structure.This work confirms that tailoring electrolyte size has significant effect on fabricating all-climate solid-state batteries.
查看更多>>摘要：Developing an effective method to synthesize high-performance high-voltage LiCoO2 is essential for its industrialization in lithium batteries(LIBs).This work proposes a simple mass-produced strategy for the first time,that is,negative temperature coefficient thermosensitive Pr6O111 nanoparticles are uniformly modified on LiCoO2 to prepare LiCoO2@Pr6O11(LCO@PrO)via a liquid-phase mixing combined with annealing method.Tested at 274 mA g-1,the modified LCO@PrO electrodes deliver excellent 4.5 V high-voltage cycling performance with capacity retention ratios of 90.8％and 80.5％at 25 and 60 ℃,being much larger than those of 22.8％and 63.2％for bare LCO electrodes.Several effective strategies were used to clearly unveil the performance enhancement mechanism induced by Pr6O111 modification.It is discovered that Pr6O111 can improve interface compatibility,exhibit improved conductivity at elevated temperature,thus enhance the Li+diffusion kinetics,and suppress the phase transformation of LCO and its resulting mechanical stresses.The 450 mAh LCO@PrO‖graphite pouch cells show excellent LIB performance and improved thermal safety characteristics.Importantly,the energy density of such pouch cell was increased even by～42％at 5 C.This extremely convenient technology is feasible for producing high-energy density LIBs with negligible cost increase,undoubtedly providing important academic inspiration for industrialization.
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