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 Ni3-MoOx/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 Ni3-MoOx/C exhibits a record high mass activity of 102.8 mA mgNi-1, a top-level exchange current density of 76.5 mu A cmNi-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. An inevitable interface reconstruction is reported by exposure to air, which can be precisely regulated by controlling Ni/Mo atomic ratios and annealing temperature. The performance for hydrogen oxidation reaction is greatly improved with a mass activity of 102.6 A g-1 and a single-cell performance of 600 mW cm-2, placing it at a world-leading level. image