Investigation of FeCo-based core-shell particles annealing using HERFD-XANES

Water electrolysis is a promising and environmentally friendly means for renewable energy storage. However, the difficulties met to replace Ir anodes by more abundant transition metal oxides (TMO) is hindering its development on a large scale. Despite numerous publications devoted to the investigation of TMOs for the oxygen evolution reaction (OER), which occurs at the anode and largely dominates the energy losses, the nature of the active sites is not fully understood yet, hindering the development of materials for water electrolysis. TMOs with spinel structure constitute a promising class of materials due to a relatively low synthesis temperature, and to their composition-dependent and widely tunable properties. In this project we study core-shell Fe3O4@CoFe2O4 nanoparticles (NPs) annealed under an oxidative atmosphere to advance the understanding of the oxidation states of the NPs under these conditions and compare it to the oxidation under a potential performed previously.

水电解是一种极具应用前景且环境友好的可再生能源存储手段。然而，以储量更为丰富的过渡金属氧化物（transition metal oxides, TMO）替代铱阳极的技术难点，正阻碍其大规模工业化应用。尽管已有大量研究围绕阳极发生且主导绝大多数能量损耗的析氧反应（oxygen evolution reaction, OER）所用TMO展开，但活性位点的本质仍未完全阐明，这进一步制约了水电解用材料的开发。尖晶石结构的过渡金属氧化物因合成温度相对较低、组分可调且性质可大范围调控，成为一类极具潜力的材料。本项目中，我们对氧化气氛下退火的核壳结构Fe₃O₄@CoFe₂O₄纳米颗粒（nanoparticles, NPs）开展研究，以期明晰该条件下纳米颗粒的氧化态，并将其与此前通过施加电位实现的氧化过程所得结果进行对比。