Bonding interface boosts the intrinsic activity and durability of NiSe@FeO heterogeneous electrocatalyst for water oxidation.

The intrinsic activity and durability of oxygen evolution reaction (OER) electrocatalysts are mainly dominated by the surface and interface properties of active materials. Herein, a core-shell heterogeneous structure (NF/NiSe@FeO) is fabricated via two-step hydrothermal method, which exhibits a low overpotential of 220 mV (or 282 mV) at 10 mA/cm (or 200 mA/cm), a small Tafel slope of 36.9 mV/dec, and long-term stability (~230 h) in 1 mol/L KOH for OER. X-ray photoelectron spectroscopy and X-ray absorption spectroscopy reveal the (oxy)hydroxide-rich surface and strong coupling interface between NiSe and FeO via the Fe-Se bond. Density functional theory calculation suggests that the d-band center and electronic state of NiSe@FeO heterojunction are well optimized due to the formation of Fe-Se bond, which is favorable for the enhanced OER activity because of the easy adsorption of oxygen-containing intermediates and desorption of O in the OER process. In addition, the unique core-shell structure and robust bonding interface are responsible for the good stability for OER. This work provides fundamental insights on the bonding effect that determine the performance of OER electrocatalyst.