NiCoP/NiOOH nanoflowers loaded on ultrahigh porosity Co foam for hydrogen evolution reaction under large current density

Abstract

Developing user-friendly electrodes for efficiently producing hydrogen from water to substitute non-renewable fossil fuels is one of the challenges in the hydrogen energy field. For the first time, we have prepared self-supporting ultrahigh porosity cobalt foam loaded with NiCoP/NiOOH nanoflowers (NiCoP/CF) via freeze-drying and phosphorization. The as-prepared hierarchical NiCoP/CF electrodes showed superior catalytic activity for hydrogen evolution reaction (HER) in alkaline media. The one resulted from phosphorization at 350 °C (NiCoP/CF-350) only required overpotential of −47, and −126 mV to deliver geometrical current density of −10 mA cm−2 and −100 mA cm−2, respectively, demonstrating improved catalytic activity than the electrodes prepared using a commercial nickel foam as a support. Moreover, it could retain its superior stability at a current density higher than −500 mA cm−2 for 16 h. Such an outstanding performance can be attributed to the ultrahigh porosity of Co foam support, optimal adsorption energies of HER intermediates (H∗), facile water dissociation on the NiCoP/NiOOH hetero-interfaces, and the assistance of NiOOH facilitating the electrons transfer from the Co foam inside to the NiCoP outside. The work would provide a new strategy for future design of advanced HER electrocatalysts.