Nanosponge-like Solid Solution of NiMo with a High Hydrogen Evolution Reaction Performance over a Wide Range of Current Densities

Owing to unstable electrical energy generation from intermittent solar and wind energy sources, the development of efficient and durable nonnoble electrocatalysts is extremely desirable, in particular, those that can be used over a wide range of current densities for the hydrogen evolution reaction (HER), especially >1 A cm–2, which is extremely desirable for energy transformation in power systems. Here, a nanosponge-like NiMo solid solution based on a nanoscale Kirkendall effect is fabricated via a one-step high-temperature sintering method. A polycrystalline layer of NiMo oxyhydroxide is formed on the surface of the as-prepared electrode after aging, thus achieving a low overpotential and Tafel slope of 37 mV at 10 mA cm–2 and 39.2 mV dec–1, respectively. The electrode displays superior electrochemical stability over a wide range of current densities without compromising its electrocatalytic activity; in particular, it is durable for over 300 h at 2 A cm–2. This is attributed to the combination of the 3D-interconnected nanosponge structure, synergistic effect between the Ni and Mo species, lattice distortion of the solid solution, and its high conductivity. This work provides a possible commercialization for the fabrication of nonprecious electrocatalysts with high performance in large-scale energy conversion.