Amorphous Co–Mo–P–O Bifunctional\nElectrocatalyst via Facile Electrodeposition for Overall Water Splitting

Abstract

Herein, amorphous\nCo–Mo–P–O was electrodeposited\non nickel foam and utilized as electrocatalysts toward water splitting.\nThe amorphous structure enabled the Co–Mo–P–O\nelectrocatalyst to have a high density of active sites, large electrochemical\nsurface area (ECSA), fast water splitting reaction kinetics, and excellent\nconductivity. An electrochemical activation was performed on the as-electrodeposited\nCo–Mo–P–O to further enhance the activity toward\noxygen evolution reaction (OER). This rendered the activated Co–Mo–P–O\nhighly catalytically active CoOOH, and further enhanced the ECSA,\nreaction kinetics, and conductivity. Utilizing the activated Co–Mo–P–O\nas an OER electrocatalyst, small overpotentials of 168.5 and 333.1\nmV were separately required for current densities of 10 and 500 mA\ncm^–2. The overpotential of 97.6 mV was required\nfor a current density of 10 mA cm^–2 toward hydrogen\nevolution reaction (HER) for the as-electrodeposited Co–Mo–P–O.\nThe as-electrodeposited and activated Co–Mo–P–O\nelectrocatalysts were paired in an integrated electrochemical cell\nfor overall water splitting; a small cell voltage of 1.57 V was needed\nto drive a current density of 10 mA cm^–2 for the\nsystem. The activity of our electrocatalysts was among the best in\nthe previously reported bifunctional electrocatalysts toward full\nwater splitting. In addition, the Co–Mo–P–O electrocatalyst\nexhibited excellent long-term stability.