Strong electronic coupling of bifunctional electrocatalyst MoO2@CoN for efficient water splitting

Herein, a highly effective bifunctional water splitting catalyst with long-term durability, MoO ₂@CoN, was successfully constructed. As discovered, the MoO ₂ /CoN interface formation resulted in the electron transfer from MoO ₂ to CoN and the generation of high-valence Mo ⁶⁺ , inducing a strong electronic polarization at interfaces and stabilizing greatly the surface electronic structure, which significantly improved the bifunctional catalytic performance and long-term stability. In alkaline electrolytes, MoO ₂ @CoN exhibited excellent bifunctional performance with quite low overpotentials of 59 mV for HER at 10 mA cm ⁻² and 227 mV for OER at 20 mA cm ⁻² , respectively, and the catalysis sustained a constant current density for more than 500 h. Theoretical calculations confirmed that Co served as an active site rather than Mo, and its HER and OER activities were considerably improved by the strong electronic polarization at interfaces. This work is important for designing efficient bifunctional catalysts by means of strong interfacial coupling.