FeSe2/CoSe2 Heterostructure with an Adjusting Electronic Structure for the Oxygen Evolution Reaction

CoSe2 has been a promising oxygen evolution reaction (OER) electrocatalyst due to its unique electronic configuration and metal behavior. However, the OER performance of CoSe2 is obviously limited by unexposed active sites. Herein, a FeSe2/CoSe2 heterostructure electrocatalyst is designed to increase the active sites of CoSe2 and shows an excellent electrocatalytic OER performance with an overpotential of 344 mV to reach the current density of 10 mA cm(-2), a small Tafel slope of 42 mV dec(-1), and an excellent stability of 60 h. The superior OER performance is ascribed to the electronic structure modulation of CoSe2 and the larger electrochemical surface area, which effectively increases the active sites for OER. This work provides a feasible way to prepare heterojunction electrocatalysts and enriches the OER electrocatalytic applications of transition metal-based selenides.