Morphology engineering of CoSe2 as efficient electrocatalyst for water splitting

Abstract Transition-metal cobalt-based chalcogenides have wide application in the fields of energy conversion and storage. Suitable morphologies can effectively improve the surface area and performance of the materials. Herein, we reported a simple and controlled strategy to fabricate the CoSe 2 with various shapes and applied these in water splitting. We successfully synthesized the spheres, wires and rods of CoSe 2 via facile hydrothermal process through regulating the addition of NH 4 F to alter the morphologies of samples. Among these samples, the as-prepared CoSe 2 spheres have urchin-like morphology with highly hollow structure, leading to large specific surface area and a great number of channels for promoting mass transfer efficiency. Therefore, the CoSe 2 spheres as electrocatalyst exhibits excellent oxygen evolution reaction and hydrogen evolution reaction performance in alkaline and acidic conditions, respectively. Electrochemical measurement illustrated that the CoSe 2 spheres as electrocatalyst shown small overpotential and superior stability, which could be a promising candidate of effective electrocatalyst.