Free-standing bimetallic CoNiTe2 nanosheets as efficient catalysts with high stability at large current density for oxygen evolution reaction

The oxygen evolution reaction (OER) step for water splitting requires highly efficient, low-cost and stable catalysts. As efficient catalytic materials for OER, bimetallic telluride (CoNiTe2/NF) nanosheets are prepared by the combination of hydrothermal and calcination method in this work. The physicochemical characterizations confirm that the surface of CoNiTe2/NF is covered by bimetallic telluride compounds (CoNiTe2) with 3D morphology composed of thin and defective nanosheets that are well-distributed on nickel foam (NF). Notably, it shows very low overpotential at 10 (181 mV), 500 (230 mV) and 1000 (270 mV) mA cm−2 and low Tafel slope (44 mV dec−1). Besides, it also exhibits excellent durability lasting 24 h at 100, 500 and 1000 mA cm−2, respectively, without distinct deactivation. This outstanding performance could be due to the bimetallic telluride and the strong covalency around the CoNi center caused by Te that plays a crucial role for enhancing the activity of catalyst. The unique morphology could provide large electrochemical active area and exposure higher amounts of active sites. Meanwhile, the self-supported structure, without binders, could also enhance the performance for OER. This work thus provides a promising strategy to synthesize multi-metal telluride materials as highly efficient and stable catalyst for OER at large current density.