Enhancement of Catalytic Activity via Inevitable Reconstruction of the Ni–Mo Interface for Alkaline Hydrogen Oxidation

Abstract The inevitable oxidation of nickel‐metal‐based catalysts exposed to the air will lead to instability and poor reproducibility of a catalytic interface, which is usually ignored and greatly hinders their application for the catalysis of alkaline hydrogen oxidation. The details on the formation of a world‐class nickel‐based HOR catalyst Ni ₃ ‐MoO _x /C‐500 are reported via an interfacial reconstruction triggered by passive oxidation upon air exposure. Interfacial reconstruction, initiated with various Ni–Mo metal ratios and annealing temperature, can fine‐tune the Ni–Mo interface with an increased work function and a reduced d‐band center. The optimized Ni ₃ ‐MoO _x /C exhibits a record high mass activity of 102.8 mA mg _Ni ⁻¹ , a top‐level exchange current density of 76.5 µA cm _Ni ⁻² , and exceptional resistance to CO poisoning at 1000 ppm CO for hours. The catalyzed alkaline exchange membrane fuel cell exhibits a maximum power output of 600 mW cm ⁻² and excellent stability, ranking it as one of the most active non‐precious metals HOR catalysts to date.