Three-dimensional core–shell structured NiCo₂O₄@CoS/Ni-Foam electrocatalyst for oxygen evolution reaction and electrocatalytic oxidation of urea

Rational construction of non-noble metal-based electrocatalysts for energy generation and environmental electrooxidation receives attention because of their simplicity, versatility, and high efficiency. In this study, a novel core–shell electroactive material architecture is developed by electrodepositing cobalt sulfide shell over core NiCo₂O₄ structure on Ni-Foam substrate, which is developed by hydrothermal process. The synergistic effect of the three-dimensional chrysanthemum-like NiCo₂O₄ with CoS shell exhibits superior activity towards oxygen evolution reaction with high durability and lower onset potential obtained at 1.52 V vs. RHE (overpotential 290 mV @ 10 mA/cm²) in alkaline solution. The electron pairs from NiCo₂O₄ and CoS along with increased active sites from their interfacial interaction considerably improve the charge transfer phenomena. The electrocatalytic activity in the presence of urea is also investigated, which aids in reducing the onset potential to 118.4 mV vs. RHE. A considerably higher current density of 78 mA/cm² is achieved at the potential of 0.5 V, which is comparatively higher than that of other electrocatalysts. Thus, the activity from sulfide/oxide core–shell architectures proves to have a high potential in efficient electrochemical reactivity producing green energy.