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 Ni₂P/CeO₂ 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 PO₄³⁻-NiOOH/CeO₂ catalyst with PO₄³⁻ adsorbed on the surface of the reconstructed product NiOOH/CeO₂. Density functional theory calculations reveal that the CeO₂ and adsorbed-PO₄³⁻ 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.