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

Abstract CoSe 2 has been a promising oxygen evolution reaction (OER) electrocatalyst due to its unique electronic configuration and metal behavior. However, the OER performance of CoSe 2 is obviously limited by unexposed active sites. Herein, a FeSe 2 /CoSe 2 heterostructure electrocatalyst is designed to increase the active sites of CoSe 2 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 CoSe 2 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.