Swelling the d/p‐Band Center Difference Induced by Heterostructure Self‐Optimization Engineering for Enhanced Water Oxidation

Abstract Monitoring the dynamic behavior of active species and modulating their electronic architecture are crucial for the development of efficient catalysts. Here, a 3D ordered multi‐level porous Ni 2 P/CeO 2 heterojunction catalyst with a “self‐optimization effect” is strategically synthesized for efficient oxygen evolution reaction (OER). This catalyst exhibits a low overpotential of 235 mV at 20 mA cm −2 in 1.0 m KOH. During the OER process, the heterojunction catalyst specifically undergoes a unique phase transition involving the leaching of the P element, which triggers the formation of the PO 4 3− ‐NiOOH/CeO 2 catalyst with PO 4 3− adsorbed on the surface of the reconstructed product NiOOH/CeO 2 . Density functional theory calculations reveal that the CeO 2 and adsorbed‐PO 4 3− in the self‐optimized structure are essential and minor factors for enhancing catalytic activity, respectively. They collaborate to promote the redistribution of electron density in surface Ni and O, increasing the d / p ‐band center difference. This phenomenon results in optimized adsorption/desorption of the key intermediates such as *OOH and improved catalytic performance. Overall, this research highlights the potential of d / p ‐band modulation for the rational design of cost‐effective and high‐efficiency electrocatalysts.