Amorphous Co–Mo–P–O Bifunctional Electrocatalyst via Facile Electrodeposition for Overall Water Splitting
Xiaoxia Wang, Guangwei She, Lixuan Mu, Wensheng Shi
Abstract
Herein, amorphous Co–Mo–P–O was electrodeposited on nickel foam and utilized as electrocatalysts toward water splitting. The amorphous structure enabled the Co–Mo–P–O electrocatalyst to have a high density of active sites, large electrochemical surface area (ECSA), fast water splitting reaction kinetics, and excellent conductivity. An electrochemical activation was performed on the as-electrodeposited Co–Mo–P–O to further enhance the activity toward oxygen evolution reaction (OER). This rendered the activated Co–Mo–P–O highly catalytically active CoOOH, and further enhanced the ECSA, reaction kinetics, and conductivity. Utilizing the activated Co–Mo–P–O as an OER electrocatalyst, small overpotentials of 168.5 and 333.1 mV were separately required for current densities of 10 and 500 mA cm–2. The overpotential of 97.6 mV was required for a current density of 10 mA cm–2 toward hydrogen evolution reaction (HER) for the as-electrodeposited Co–Mo–P–O. The as-electrodeposited and activated Co–Mo–P–O electrocatalysts were paired in an integrated electrochemical cell for overall water splitting; a small cell voltage of 1.57 V was needed to drive a current density of 10 mA cm–2 for the system. The activity of our electrocatalysts was among the best in the previously reported bifunctional electrocatalysts toward full water splitting. In addition, the Co–Mo–P–O electrocatalyst exhibited excellent long-term stability.