CeO 2 ‐Accelerated Surface Reconstruction of CoSe 2 Nanoneedle Forms Active CeO 2 @CoOOH Interface to Boost Oxygen Evolution Reaction for Water Splitting

Abstract Interface engineering is an efficient strategy to create high‐performance electrocatalysts for water splitting. In the present work, CeO 2 @CoSe 2 nanoneedle on carbon cloth (CeO 2 @CoSe 2 /CC) demonstrates high efficiency for oxygen evolution reaction (OER) and water splitting. CeO 2 with abundant O vacancies facilitates the adsorption of OH − and boosts the reconstruction of CoSe 2 into CoOOH at lower potentials. The in situ generated active CeO 2 @CoOOH heterointerface upshifts the d‐band center of Co site, thereby decreasing the free energy of rate‐determining step (RDS) ( * O to * OOH) during the OER process. It delivers a low OER overpotential of 245 mV at 10 mA cm −2 . CeO 2 @CoSe 2 /CC is also found to be active for hydrogen evolution reaction (HER, 138 mV overpotential at 10 mA cm −2 ), profiting from CeO 2 ‐facilitated * H 2 O dissociation and * H adsorption on CoSe 2 . The overall water splitting is achieved over the CeO 2 @CoSe 2 /CC bifunctional electrode with a low electrolysis voltage of 1.54 V at 10 mA cm −2 . This work offers valuable insights into CeO 2 ‐assisted surface reconstruction as well as provides water electrolysis catalysts through interface engineering.