Ce Modification Induces Interfacial Electron Reconstruction to Stabilize Co(OH) ₂ Framework and Enhance Hydrogen Evolution Reaction Kinetics

ABSTRACT A central challenge in alkaline water electrolysis is the development of hydrogen evolution reaction (HER) electrocatalysts that simultaneously maintain high activity and structural stability at industrial current densities. Hydroxide‐based supports that facilitate water dissociation are particularly susceptible to over‐reduction and structural degradation under strongly cathodic conditions. Here, we demonstrate that incorporating CeO ₂ into a Pt/CeO ₂ –Co(OH) ₂ composite catalyst effectively addresses the inherent instability of Co‐based supports under reductive conditions. By reconstructing the interfacial electronic environment, this design helps mitigate the over‐reduction of the Co(OH) ₂ component during the HER, thereby preserving the Co‐related sites for water dissociation while concurrently modulating the electronic structure of Pt to optimize hydrogen adsorption. The resulting catalyst achieves ultralow overpotentials of 39 and 156 mV at 10 and 500 mA cm ⁻² , respectively, and operates stably for 550 h at 500 mA cm ⁻² . When integrated into an anion exchange membrane electrolyzer, it enables efficient water splitting at 1.0 A cm ⁻² for 250 h with a decay rate of only 0.488 mV h ⁻¹ . These findings highlight the critical role of interfacial electronic regulation in stabilizing hydroxide‐based supports and provide a viable strategy for the design of durable high‐performance electrocatalysts.