Morphology controlled synthesis of 2-d Ni–Ni₃S₂ and ni₃s₂ nanostructures on ni foam towards oxygen evolution reaction

Catalysts for oxygen evolution reactions (OER) are at the heart of key renewable energy technologies, and development of non-precious metal catalysts with high activity and stability remain a great challenge in this field. Among various material candidates, metal sulfides are receiving increasing attention. While morphology-dependent catalytic performances are well established in noble metal-based catalysts, relatively little is known for the morphology‒cata-lytic performance relationship in metal sulfide catalysts. In this study, uniform spider web-like Ni nanosheets–Ni₃S₂ and honeycomb-like Ni₃S₂ structures are deposited on nickel foam (Ni₃S₂/NF) by a facile one-step hydrothermal synthetic route. When used as an oxygen evolution electrode, the spider web-like Ni–Ni₃S₂/NF with the large exposed surface area shown excellent catalytic activity and stability with an overpotential of ~310 mV to achieve at 10 mA/ cm² and a Tafel slope of 63 mV/dec in alkaline media, which is superior to the honeycomb-like structure without Ni nanosheet. The low Tafel slope of the spider web-like Ni–Ni₃S₂/NF represents one of the best OER kinetics among nickel sulfide-based OER catalysts. The results point to the fact that performance of the metal sulfide electrocatalysts might be fine-tuned and optimized with morphological controls.