Freestanding Surface Disordered NiCu Solid Solution as Ultrastable High Current Density Hydrogen Evolution Reaction Electrode.

The poor performance of conventional powdery catalysts under large current density and the slow kinetics of the Volmer step limit the large-scale application of alkaline hydrogen generation. Here, we report the preparation of freestanding surface disordered NiCu solid solution as an ultrastable hydrogen evolution reaction electrode. The introduction of ammonium ion could tailor the reduction/nucleation rate of metal ions during the hydrothermal process, thus contributing to its unique intertwined 3D microstructure. The catalyst exhibits superior HER activity with an overpotential of 322 mV at 1000 mA cm-2, and limited degradation after 110 h continuous operation at 1000 mA cm-2. Density functional theory calculations confirm that the substitution of Cu could accelerate the hydroxyl desorption process (OHads + e- → OH-) and thereby enhance the overall kinetics of the Volmer step. Our work demonstrates the strong efficacy of optimizing catalysts' structures and facilitating intermediate desorption for boosting industrial-scale alkaline HER performance.