Surface Reconstruction of Co₄N Coupled with CeO₂ toward Enhanced Alkaline Oxygen Evolution Reaction

Constructing the active interface in a heterojunction electrocatalyst is critical for the electron transfer and intermediate adsorption (O*, OH*, and HOO*) in alkaline oxygen evolution reaction (OER) but still remains challenging. Herein, a CeO₂/Co₄N heterostructure is rationally synthesized through the direct calcination of Ce[Co(CN)₆], followed by thermal nitridation. The in situ electrochemically generated CoOOH on the surface of Co₄N serves as the active site for the OER, and the coupled CeO₂ with oxygen vacancy can optimize the energy barrier of intermediate reactions of the OER, which simultaneously boosts the OER performance. Besides, electrochemical measurement results demonstrate that oxygen vacancies in CeO₂ and optimized absorption free energy originating from the electron transfer between CeO₂ and CoOOH contribute to enhanced OER kinetics. This work provides new insight into regulating the interface heterostructure to rationally design efficient OER electrocatalysts under alkaline conditions.