醇盐自模板法构筑碳封装NiFeV基电催化剂用于析氧反应

Constructing Carbon-Encapsulated NiFeV-Based Electrocatalysts by Alkoxide-Based Self-Template Method for Oxygen Evolution Reaction

发展绿色可持续的水电解制氢技术有利于实现“碳中和”战略目标,而开发高效稳定的析氧反应催化剂对水电解技术至关重要。本研究以NiFeV固态金属醇盐为前驱体,采用醇盐自模板法制备碳封装NiFeV基催化剂。研究结果表明,NiFeV基催化剂呈现出均匀的球状结构,用于电解水析氧反应电催化剂时仅需381 mV的过电位即可获得20 mA·cm^(–2)的电流密度。NiFeV基催化剂良好的催化活性和稳定性主要得益于均匀的球状结构,V对电子结构的优化调控以及封装碳层对金属颗粒的保护作用。此工作通过V掺杂和碳封装的策略,为提升析氧催化剂的电催化性能提供了有利借鉴。

The development of green and sustainable water-splitting hydrogen production technology is beneficial to reducing the over-reliance on fossil fuels and realizing the strategic goal of"carbon neutral".As one of the half reactions for water splitting,oxygen evolution reaction has suffered the problems of sluggish four-electron transfer process and relatively slow reaction kinetics.Therefore,exploring efficient and stable catalysts for oxygen evolution reaction is of critical importance for water-splitting technology.Metal alkoxides are a series of compounds formed by the coordination function of metal ions with alcohol molecules.Metal alkoxides possess the double advantages of organic materials and inorganic materials,which makes them reveal a promising application in the electrochemical field.In view of the poor activity and stability of the current oxygen evolution reaction electrocatalysts,this study has adopted the alkoxide-based self-template method to prepare the carbon-encapsulated NiFeV-based electrocatalysts through using the solid NiFeV-alkoxides as precursors.The organic components in solid metal alkoxides are employed to achieve the graphitized carbon encapsulation after the high-temperature calcination process,which is beneficial for improving the conductivity and corrosion resistance of catalysts.Through adjusting the V doping amounts and the calcination temperatures,the electronic structure of NiFe nanoparticles and carbon encapsulation were optimized,which are both key influence factors for oxygen evolution performances.As a result,the oxygen evolution catalysts with high activity and stability were obtained successfully in this work.The experimental results have shown that the NiFeV-based catalysts presented a uniform spherical structure with carbon encapsulation.The current density of 20 mA·cm^(−2)could be obtained at the overpotential of only 381 mV as an electrocatalyst for oxygen evolution reaction in water electrolysis.After the continuous 10000 s durability test,the NiFeV-based catalyst exhibited slight reduction in current density but still maintained the catalytic activity almost similar to the initial one,revealing a good oxygen evolution stability.The excellent catalytic activity and stability of NiFeV-based catalysts are believed to be mainly attributed to the uniform spherical structure,the optimized regulation of V on the electronic structure and the protective effect of carbon encapsulation on metal particles.The V element in the catalysts exhibited the rich redox states of V^(3+),V^(4+)and V^(5+),which can effectively adjust the electronic structure of adjacent atoms and optimize the binding energy of oxygen reduction reaction intermediates,thus improving the electrocatalytic performance of catalysts.This work provides a useful guidance for improving the electrocatalytic performance of oxygen evolution catalysts through the V-doping and carbon encapsulation strategies.