Revealing Active Function of Multicomponent Electrocatalysts from In Situ Nickel Redox for Oxygen Evolution

The microscopic electrode process of oxygen evolution reaction (OER) is crucial for the rational design of efficient multiscale systems in modern electrocatalysis, which needs to be elaborately clarified, especially for catalysts with various components. In this work, beginning with electrochemical redox behavior analysis of nickel species, the active function of multicomponent catalysts (here carbon-contained FeNi-based metals/hydroxides) for OER was elucidated. The component FeNi layered double hydroxides experienced in situ electrochemical transformation, which were further verified as actual species for dominating OER. By kinetic modeling, the surface reactive intermediate *OH featured a volcano plot with an increase in potential, while *O emerged to a saturated coverage to ensure unhindered progress of the rate-determining step (*O → *OOH), thus endowing the overall OER with a fast rate. This case study facilitates understanding of the fundamental activities of a multicomponent electrode on the electrocatalytic reaction, which contributes to developing novel materials for future application in electrochemical energy conversion and storage.