Efficient Co@CoPx core–shell nanochains catalyst for the oxygen evolution reaction

Abstract

Co@CoP_x core–shell nanochains were prepared via a direct-current arc-discharge method and subsequent phosphorization at 350 °C. The nanochains comprise nanospheres connected to each other with a length of several micrometers. The amount of CoP_x can be easily changed by varying the phosphorization time. In the Co@CoP_x core–shell structure, Co serves as a conductive channel, which improves the reaction kinetics of the oxygen evolution process on CoP_x. Co metal can also inject electrons into CoP_x, thus changing the work function of CoP_x and improving its oxygen evolution efficiency. Based on the optimized structure, the Co@CoP_x nanochains catalyst exhibits excellent oxygen evolution performance. Co@CoP_x achieves an overpotential of 310 mV at a current density of 10 mA cm⁻², which is lower than that of CoP_x (418 mV), Co (408 mV), and RuO₂ (317 mV). Furthermore, Co@CoP_x exhibits good durability during the long-term electrochemical test.