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.