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

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.