Hierarchical Ni3S2 nanosheets coated on Co3O4 nanoneedle arrays on 3D nickel foam as an efficient electrocatalyst for the oxygen evolution reaction

Abstract

The controlled storage and release of hydrogen are still pivotal issues for upcoming hydrogen economy due to the imminent depletion of energy from traditional sources. The synthesis of water oxidation electrocatalysts which are low-cost, earth-abundant and highly efficient is an important prerequisite for the release of hydrogen from water under mild conditions for practical applications. In this article, we have designed and investigated a 3D hybrid Co₃O₄@Ni₃S₂/NF composite via successive hydrothermal and calcination methods for the first time, in which Ni₃S₂ nanosheets coated on Co₃O₄ nanoneedle arrays with unique hierarchically porous morphology were directly grown on nickel foam. Due to the positive synergistic effect of the 1D Co₃O₄ nanoneedles and the 2D Ni₃S₂ nanosheets, the hybrid Co₃O₄@Ni₃S₂/NF composite can be considered to be an efficient oxygen evolution reaction (OER) catalyst with an overpotential of 260 mV at a current density of 20 mA cm⁻² in 1.0 M KOH. The combination of Co₃O₄ and in situ formed α-Ni(OH)₂ on the surface of Ni₃S₂ nanosheets during the OER resulted in dramatic electrocatalyst performance and excellent stability, providing a novel approach for the design of an effective and efficient OER electrode.