释放多孔纳米结构的活力:可持续电催化水分解

电化学整体水分解(OWS)作为一种很有应用前景的能源转换技术,可用于生产清洁的可再生氢燃料,引起了人们的广泛关注.然而,水分解反应的半反应,即析氧反应(OER),因动力学缓慢、水分解热力学势垒高和能量消耗大等问题制约了OWS的广泛应用.研究发现,采用地球储量丰富的元素设计的多孔材料可以显著提高活性位点数量及其可及性,增大比表面积,优化反应物的吸附/脱附,改善传质,进而表现出较好的电催化活性.因此,系统梳理总结多孔纳米材料在电催化分解水领域的研究进展具有重要的意义.本文综述了近年来用于析氢反应,OER和OWS的多孔电催化剂的研究进展.聚焦于合成策略的最新进展,并结合多孔结构在电催化剂中的独特作用进行了讨论.概述了各种新兴的多孔电催化剂改性策略,包括结构工程、相工程、缺陷工程和应变工程;重点介绍了合成方法、多孔材料性能提升、机理理解、集成实验、水分解的理论研究和先进的改性策略,并提出了合成工艺.特别总结了结构-活性关系的研究成果,为设计和改性具有独特性能的多孔材料提供参考.最后,本文强调了当前多孔电催化剂所面临的科学挑战和未来发展方向,旨在为推动多孔电催化剂在电化学水分解领域的应用和发展提供借鉴.

Status and Opportunities of Zinc Ion Hybrid Capacitors: Focus on Carbon Materials, Current Collectors, and Separators

Zinc ion hybrid capacitors(ZIHCs), which integrate the features of the high power of supercapacitors and the high energy of zinc ion batteries, are promising competitors in future electrochemical energy storage applications. Carbon-based materials are deemed the competitive candidates for cathodes of ZIHC due to their cost-effectiveness, high electronic conductivity, chemical inertness, controllable surface states, and tunable pore architectures. In recent years, great research efforts have been devoted to further improving the energy density and cycling stability of ZIHCs. Reasonable modification and optimization of carbon-based materials offer a remedy for these challenges. In this review, the structural design, and electrochemical properties of carbon-based cathode materials with different dimensions, as well as the selection of compatible, robust current collectors and separators for ZIHCs are discussed. The challenges and prospects of ZIHCs are showcased to guide the innovative development of carbon-based cathode materials and the development of novel ZIHCs.

One-step synthesis of graphitic-C_3N_4/ZnS composites for enhanced supercapacitor performance

A series of graphitic-C3N4/ZnS（g-C3N4/ZnS） supercapacitor electrode materials have been prepared via a one-step calcination process of zinc acetate/thiourea with different mass ratios under nitrogen atmosphere. The optimized g-C3N4/ZnS composite shows a highest specific capacitance of 497.7 F/g at 1 A/g and good cycling stability with capacitance retention of 80.4% at 5 A/g after 1000 cycles. Moreover, gC3N4/ZnS composites display an improved supercapacitor performance in terms of specific capacitance compared to the pure g-C3N4 and ZnS. In addition, our designed symmetric supercapacitor device based on g-C3N4/ZnS composite electrodes can exhibit an energy density of 10.4 Wh/kg at a power density of 187.3 W/kg. As a result, g-C3N4/ZnS composites are expected to be a prospective material for supercapacitors and other energy storage applications.

Screening of transition metal oxides for electrocatalytic nitrate reduction to ammonia at large currents

Electrochemical nitrate reduction reaction(NO_(3)RR)towards ammonia,as an emerging and appealing technology alternative to the energy-intensive Haber-Bosch process and inefficient nitrogen reduction reaction,has recently aroused wide concern and research.However,the current research of the NO_(3)RR towards ammonia lacks the overall performance comparison of various electrocatalysts.Given this,we here make a comparison of 12 common transition metal oxide catalysts for the NO_(3)RR under a high cathodic current density of 0.25 A·cm^(-2),wherein Co_(3)O_(4) catalyst displays the highest ammonia Faradaic efficiency(85.15%)and moderate activity(ca.-0.25 V vs.reversible hydrogen electrode).Other external factors,such as nitrate concentrations in the electrolyte and applied potential ranges,have also been specifically investigated for the NO_(3)RR.

Heterointerface engineering of Ni/Ni_(3)N hierarchical nanoarrays for efficient alkaline hydrogen evolution

Ni-based transition metal nitrides(TMNs)have been regarded as promising substitutes for noble-metal electrocatalysts towards the hydrogen evolution reaction(HER)due to their low cost,excellent chemical stability,high electronic conductivity,and unique electronic structure.However,facile green synthesis and rational microstructure design of Ni-based TMNs electrocatalysts with high HER activity remain challenging.In this work,we report the fabrication of Ni/Ni_(3)N heterostructure nanoarrays on carbon paper via a one-step magnetron sputtering method under low temperature and N2 atmosphere.The Ni/Ni_(3)N hierarchical nanoarrays exhibit an excellent HER catalytic activity with a low overpotential of 37 mV at 10 mA·cm^(−2)and robust long-term durability over 100 h.Furthermore,the Ni/Ni_(3)N||NiFeOH(NiFeOH=NiFe bimetallic hydroxide)electrolyzer requires a small voltage of 1.54 V to obtain 10 mA·cm^(−2)for water electrolysis.Density functional theory(DFT)calculations reveal that the heterointerface between Ni and Ni_(3)N could directly induce electron redistribution to optimize the electronic structure,which accelerates the dissociation of water molecules and the subsequent hydrogen desorption,and thus boosting the HER kinetics.

Recent progress in advanced catalysts for electrocatalytic hydrogenation of organics in aqueous conditions

Electrocatalytic hydrogenation(ECH)of organics using water as hydrogen donors has been regarded as a green organic reduction technique to replace traditional chemical reactions that use sacrificial chemicals.The development of ECH process provides potential applications in the production of value-added chemicals owing to its low energy consumption,low pollution,high safety,and superior sustainability.However,its application is limited by the low conversion rate and poor selectivity toward desired products.The efficiency of ECH can be improved by rational design of electrocatalysts.This review covers several representative electrocatalytic systems(aldehydes,ketones,phenolic organics,alkynes,and organonitrogen compounds)and summarizes different ECH mechanisms,followed by thorough discussion on the modification strategies of electrocatalysts that are currently adopted to enhance the catalytic performance.Finally,in view of the current challenges for ECH,we discuss possible future directions in the field,aiming to provide guidance to the catalyst design toward highly efficient ECH reactions over different organic feedstocks.

Recent advances in anode materials for potassium-ion batteries:A review

Potassium-ion batteries(PIBs)are appealing alternatives to conventional lithium-ion batteries(LIBs)because of their wide potential window,fast ionic conductivity in the electrolyte,and reduced cost.However,PIBs suffer from sluggish K+reaction kinetics in electrode materials,large volume expansion of electroactive materials,and the unstable solid electrolyte interphase.Various strategies,especially in terms of electrode design,have been proposed to address these issues.In this review,the recent progress on advanced anode materials of PIBs is systematically discussed,ranging from the design principles,and nanoscale fabrication and engineering to the structure-performance relationship.Finally,the remaining limitations,potential solutions,and possible research directions for the development of PIBs towards practical applications are presented.This review will provide new insights into the lab development and real-world applications of PIBs.

Interface engineering of Zn meal anodes using electrochemically inert Al_(2)O_(3)protective nanocoatings

Aqueous rechargeable Zn-ion batteries are regarded as a promising alternative to lithium-ion batteries owing to their high energy density,low cost,and high safety.However,their commercialization is severely restricted by the Zn dendrite formation and side reactions.Herein,we propose that these issues can be minimized by modifying the interfacial properties through introducing electrochemically inert Al_(2)O_(3)nanocoatings on Zn meal anodes(Al_(2)O_(3)@Zn).The Al_(2)O_(3)nanocoatings can effectively suppress both the dendrite growth and side reactions.As a result,the Al_(2)O_(3)@Zn symmetric cells show excellent electrochemical performance with a long lifespan of more than 4,000 h at 1 mA·cm^(−2)and 1 mAh·cm^(−2).Meanwhile,the assembled Al_(2)O_(3)@Zn//V_(2)O_(5)full cells can deliver a high capacity(236.2 mAh·g^(−1))and long lifespan with a capacity retention of 76.11%after 1,000 cycles at 4 A·g^(−1).

Conversion of hydroxide into carbon-coated phosphide using plasma for sodium ion batteries

Transition metal phosphides(TMPs)are promising candidates for sodium ion battery anode materials because of their high theoretical capacity and earth abundance.Similar to many other P-based conversion type electrodes,TMPs suffer from large volumetric expansion upon cycling and thus quick performance fading.Moreover,TMPs are easily oxidized in air,resulting in a surface phosphate layer that not only decreases the electric conductivity but also hinders the Na ion transport.In this work,we present a general electrode design that overcomes these two major challenges facing TMPs.Using metal hydroxide and glucose as precursors,we show that the metal hydroxide can be converted into phosphide whereas the glucose simultaneously decomposes and forms carbon shell on the phosphide particles under a plasma ambient.Ni2P@C core shell structures as a proof-of-concept are designed and synthesized.The in situ formed carbon shell protects the Ni2P from oxidation.Moreover,the high-energy plasma introduces porosity and vacancies to the Ni2P and more importantly produces phosphorus-rich nickel phosphides(NiPx).As a result,the Ni2P@C electrodes achieve high sodium capacity(693 mAh·g^(−1) after 50 cycles at 100 mA·g^(−1))and excellent cyclability(steady capacity maintained for at least 1,500 cycles).Our work provides a general strategy for enhancing the sodium storage performance of TMPs,and in general many other conversion type electrode materials that are unstable in air and suffer from large volumetric changes upon cycling.

Tungsten Blue Oxide as a Reusable Electrocatalyst for Acidic Water Oxidation by Plasma-Induced Vacancy Engineering

In contrast to alkaline water electrolysis,acidic water electrolysis remains an elusive goal due to the lack of earth-abundant,efficient,and acid-stable water oxidation electrocatalysts.Here,we show that materials with intrinsically poor electrocatalytic activity can be turned into active electrocatalysts that drive the acidic oxygen evolution reaction(OER)effectively.This development is achieved through ultrafast plasma sputtering,which introduces abundant oxygen vacancies that reconstruct the surface electronic structures,and thus,regulated the surface interactions of electrocatalysts and the OER intermediates.Using tungsten oxide(WO_(3))as an example,we present a broad spectrum of theoretical and experimental characterizations that show an improved energetics of OER originating from surface oxygen vacancies and resulting in a significantly boosted OER performance,compared with pristine WO_(3).Our result suggests the efficacy of using defect chemistry to modify electronic properties and hence to improve the OER performance of known materials with poor activity,providing a new direction for the discovery of acid-stable OER catalysts.

Layered SnS sodium ion battery anodes synthesized near room temperature

In this report, we demonstrate a simple chemical bath deposition approach for the synthesis of layered SnS nanosheets （typically 6 nm or -10 layers thick） at very low temperature （40℃）. We successfully synthesized SnS/C hybrid electrodes using a solution-based carbon precursor coating with subsequent carbonization strategy. Our data showed that the ultrathin carbon shell was critical to the cycling stability of the SnS electrodes. As a result, the as-prepared binder-free SnS/C electrodes showed excellent performance as sodium ion battery anodes. Specifically, the SnS/C anodes delivered a reversible capacity as high as 792 mAh-g-1 after 100 cycles at a current density of 100 mA·g-1 They also had superior rate capability （431 mAh.g-1 at 3,000 mA.g-1） and stable long-term cycling performance under a high current density （345 mAh-g-1 after 500 cycles at 3 A.g-1）. Our approach opens up a new route to synthesize SnS-based hybrid materials at low temperatures for energy storage and other applications. Our process will be particularly useful for chalcogenide matrix materials that are sensitive to high temperatures during solution synthesis.