High surface area NiCoP nanostructure as efficient water splitting electrocatalyst for the oxygen evolution reaction

We present a simple route to synthesize of porous bi-metallic phosphides with large surface area supporting high density of electrochemically active sites, and demonstrate that resulting Ni0.2Co0.8P exhibits outstanding performance in catalysing oxygen evolution reaction (OER) under alkaline condition. It requires a very low over potential of 230 mV to achieve an anodic current density of 10 mA cm−2 with a Tafel slope of 44 mV dec−1. Ni0.2Co0.8P is also shown to perform well in catalyzing hydrogen evolution reaction (HER) under both alkaline (0.1 M KOH solution) and acidic conditions (0.5 M H2SO4 solution). Through first-principles theoretical analysis, we show that such high catalytic activity arises from the synergistic effect of Ni and Co on energies of d and p bands of Ni0.2Co0.8P, which is further enhanced by rapid mass transport possible due to the porous architecture of its three-dimensional network morphology.