Three-dimensional Co3O4@NiCo2O4 nanoarrays with different morphologies as electrocatalysts for oxygen evolution reaction

Oxygen evolution reaction is one of the key factors restricting the whole process of electrolysis of water. In this paper, hydrothermal and calcination method are used to in situ grow Co₃O₄@NiCo₂O₄ on nickel foam (NF). The formation of Co₃O₄@NiCo₂O₄ nanostructures depends on the different hydrothermal time, which further results in the different growth mechanism of Co₃O₄@NiCo₂O₄ nanostructures. The result shows that Co₃O₄@NiCo₂O₄-8h, as a catalytic material, could play a synergistic role to largely accelerate the electron transfer process and could be efficiently and persistently used in oxygen evolution reaction. The oxygen evolution reaction activity of Co₃O₄@NiCo₂O₄-8h material is significantly improved compared with Co₃O₄, Co₃O₄@NiCo₂O₄-6h and Co₃O₄@NiCo₂O₄-10 h. When the current density is 50 mA cm⁻², the overpotential is only 290 mV for Co₃O₄@NiCo₂O₄-8h material. The enhanced activity Co₃O₄@NiCo₂O₄-8h is attributed to more active site exposure, rapid charge transfer and synergistic catalysis of Co₃O₄ and NiCo₂O₄. This work provides a new idea for the development of efficient, stable and environmentally friendly hybrid catalysts.