Morphology engineering of CoSe2 as efficient electrocatalyst for water splitting.

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 CoSe2 with various shapes and applied these in water splitting. We successfully synthesized the spheres, wires and rods of CoSe2 via facile hydrothermal process through regulating the addition of NH4F to alter the morphologies of samples. Among these samples, the as-prepared CoSe2 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 CoSe2 spheres as electrocatalyst exhibits excellent oxygen evolution reaction and hydrogen evolution reaction performance in alkaline and acidic conditions, respectively. Electrochemical measurement illustrated that the CoSe2 spheres as electrocatalyst shown small overpotential and superior stability, which could be a promising candidate of effective electrocatalyst.