Oxygenophilic Cerium Promotes Active Species Generation and Modulates the Interfacial Water Network in Electrocatalytic Water Oxidation

ABSTRACT Moderate uptake of OH ⁻ on the catalyst surface is the crucial initial step in alkaline oxygen evolution reaction (OER). It directly influences the generation and turnover frequency (TOF) of actual active sites. Here, the highly oxygen‐affinity cerium oxide dendrites modified nickel sulfide–based hexagonal star‐like nanorod (NR) arrays electrode was constructed (CeO ₂ @NiS _x /C ₃ N ₄ ). The optimized CeO ₂ @NiS _x /C ₃ N ₄ exhibits an improved OER overpotential of 279 mV at 100 mA cm ⁻² and a Tafel slope of 54 mV dec ⁻¹ under alkaline circumstances. X‐ray absorption spectroscopy (XAS), in situ Raman spectra and density functional theory (DFT) calculations reveal that the incorporated Ce effectively modifies the local electronic configuration of pristine Ni−S structure, introduces abundant oxygen vacancies, promotes the transformation of Ni sites into active NiOOH species, and balances hydroxyl ions (OH ⁻ ) adsorption. Moreover, in situ Raman spectra confirm the positive role of CeO ₂ dendrites in leveraging the rigid network of interfacial water, assisting the uptake of oxygen‐containing reaction intermediates in the initial stage of OER. This work provides valuable insights into the design and fabrication of electrocatalytic electrodes modified with rare‐earth compounds for applications in electrochemical energy conversion.