Synergistic interface engineering and structural optimization over hydroxide-phosphide nanoarray electrocatalysts for efficient alkaline water electrolysis

Developing transitional metal-based electrocatalysts with outstanding oxygen evolution reaction (OER) and hydrogen evolution reaction (HER) performance is essential for energy-efficiency alkaline water electrolysis. Herein, a group of heterostructured electrocatalysts constructing of nickel-based hydroxide (NiX(OH)_x, X = Co, Fe) nanosheets decorated on copper phosphide nanowires arrays，were fabricated. Both of the as-prepared NiCo(OH)_x-CuP/CF and NiFe(OH)_x-CuP/CF present outstanding HER and OER activity, with the overpotential of 79 and 202 mV to deliver 10 mA cm⁻², respectively, along with considerable long-term stability. Encouragingly, the NiCo(OH)_x-CuP/CF ǀǀ NiFe(OH)_x-CuP/CF couple enables sustainable alkaline water electrolysis and powered by a solar-powered system. In-depth analyses elucidate that owing to the modulated heterogeneous interfacial states, both of the catalytic kinetics can be optimized targeting HER and OER, respectively. More significantly, a regulated electrode-electrolyte microenvironment induced by unique arrays nanostructure efficiently promote the electron-mass transfer capacity, thereby facilitating the catalytic activity expression. This work demonstrates the desirable catalytic performance by rationally designing of hydroxide-phosphide heterostructure, and highlights the structural features on catalytic performance promotion.