Quasi-parallel nickel cobalt phosphide nanosheet arrays as highly efficient electrocatalyst for hydrogen evolution and overall water splitting at large current densities

Abstract

Developing electrocatalysts with high activity for the hydrogen evolution reaction (HER) is a key prerequisite for overall water splitting. Herein, quasi-parallel NiCo phosphide (NiCoP) nanosheet arrays exhibiting a domain arrangement are grown onto Ni foam via a facile hydrothermal process followed by phosphorization. Benefiting from the strong interaction between Ni foam substrate and the as-loaded materials, quasi-parallel NiCo phosphide nanoarrays exhibit low resistance nature, high electrocatalytic activity and excellent stability toward HER in pH-universal electrolytes. Especially, it delivers the overpotential of 53 mV, 55 mV and 92 mV at 10 mA cm −2 in acidic, alkaline and neutral media, respectively. Impressively, the catalyst shows large current densities of 1000 mA cm −2 at low overpotentials, outperforming that of the commercial precious metal-based catalysts as well as the NiCoP nanosheet arrays with random alignment. Moreover, this novel and highly active catalyst enables a water splitting electrolyzer operating at the cell voltage of 1.49 V and 1.85 V to offer 10 mA cm −2 and 500 mA cm −2 in 1.0 M KOH at room temperature, together with high durability. • Quasi-parallel NiCoP nanosheet arrays with domain pattern are grown on Ni foam. • Enhanced interaction between NiCoP nanosheet arrays and Ni substrate. • HER Overpotentials of 53 and 55 at 10 mA/cm 2 in acidic and alkaline media. • Deliver 500 and 1000 mA/cm 2 at 171 mV and 193 mV in KOH solution for HER. • 1.49 V and 1.85 V to drive 10 and 500 mA/cm 2 for overall water splitting.