Low-crystallinity mesoporous NiGaFe hydroxide nanosheets on macroporous Ni foam for high-efficiency oxygen evolution electrocatalysis

Abstract

The exploitation of cost-effective and robust electrocatalysts for the oxygen evolution reaction (OER) is paramount for renewable energy technologies. Herein, we developed a hierarchically-structured self-supported electrode by directly electrodepositing low-crystallinity mesoporous NiGaFe hydroxide nanosheets onto macroporous nickel foam. Benefiting from the favorable mass transport ability of the hierarchical structure, abundant active sites and relatively high conductivity from low crystallinity, and optimized energetics for OER intermediates by introducing Ga and Fe on the basis of density functional theory simulations, the Ni_0.65Ga_0.30Fe_0.05 hydroxide delivers superior OER electrocatalytic performances with very low overpotential (only 200 mV at 10 mA cm⁻²) and Tafel slope (42 mV dec⁻¹), outperforming most of the reported OER electrocatalysts. Moreover, this hybrid electrode exhibits a high faradaic efficiency of 96% and superior durability for 100 h at 20 mA cm⁻² without obvious degradation, showing great potential for application in low-cost and high-efficiency OER electrocatalysis.