Controllable synthesis of three dimensional electrodeposited Co–P nanosphere arrays as efficient electrocatalysts for overall water splitting

Abstract

Novel three dimensional (3D) electrodeposited Co–P nanosphere arrays on FTO (Co–P/FTO) have been successfully prepared as efficient bifunctional electrocatalysts for overall water splitting in alkaline media. The morphologies and properties of the 3D Co–P nanosphere arrays can be controlled by the electrolyte concentration. At the middle concentration, Co–P nanospheres have a more homogeneous size and array distribution and a rough surface, implying a larger surface area and an increased number of active sites for water splitting. The electrochemical measurements confirm the best electrocatalytic performances of Co–P/FTO at the middle concentration. They show excellent activity, with an overpotential of 125 mV for HER, 420 mV for OER and Tafel slopes of 54 mV dec⁻¹ and 83 mV dec⁻¹, respectively. The fabricated bifunctional systems of Co–P/Co–P can efficiently catalyse HER and OER at the same time, solving the incompatible problem of different media between HER and OER. Therefore, controlling the synthesis of 3D Co–P/FTO nanosphere arrays through electrodeposition can provide a facile way for the bifunctional electrocatalysis of both HER and OER.