D–P Orbitals Hybridization Triggered Electron Pumping in Fe–O–Mo Bridged Structure for Efficient Water Electrolysis

Abstract

Interfacial engineering is widely used in the design of heterostructured electrocatalysts for water electrolysis, yet the effects of nonmetallic bridging bonds and interfacial electric fields on electrocatalytic activity have rarely been explored. Herein, we propose a novel interfacial Fe–O–Mo bridged structure to investigate the effect of oxygen bridging bonds on the electronic structure and electrocatalytic activity of metal sites within a P-MoO3/LDH heterostructure. Comprehensive analyses reveal that Mo(6-δ)+ sites act as “electron pump”, extracting electrons from symmetric Fe sites via oxygen bridging bonds, which promotes the formation of empty eg orbitals on Fe. Moreover, strong d–p orbital hybridization at the interfaces shifts the d-band center of Fe upward, enhancing oxygen adsorption, while the p-band center of O shifts downward, enhancing proton adsorption, thereby synergistically accelerating the electrocatalytic kinetics of oxygen evolution reaction (OER) and hydrogen evolution reaction (HER). Consequently, the P-MoO3/LDH heterostructure achieves low overpotentials of 89 mV for HER and 230 mV for OER at 10 mA cm–2, and demonstrates excellent performance in commercial alkaline anion-exchange membrane water electrolyzer (AAEMWE), highlighting its significant industrial potential. This work underscores the design of an Fe–O–Mo bridged structure via d–p orbital hybridization and elucidates the Mo(6-δ)+ “electron pump” effect, offering new insights for efficient electrocatalyst development.

Keywords: Orbital hybridization, Electron pumping, Oxygen bridging, Heterostructure, Water Electrolysis