In Situ Controllably Self-Assembled CoFe Oxide Nanosheet Arrays As Efficient Catalytic Electrodes for Oxygen Evolution Reaction at Large Current Density.

To advance the hydrogen energy economy, developing efficient water-splitting catalysts is crucial. As a potential candidate for industrial applications, the catalytic performance of CoFe2O4 at a large current density needs to be optimized in combination with a variety of strategies. Here, a brand-new In-doped cobalt ferrite/nickel selenide (CoFe1.7In0.3O4/NiSe2) heterojunction with genuine potential as a highly effective electrocatalyst for the OER at a large current density was reported. Density functional theory calculations demonstrate that the performance enhancement is ascribed to heterogeneous atom doping and a self-supported electrode consisting of cobalt ferrite/nickel selenide heterostructures, which reduce the band center of the Fe d orbit and narrow the band gap of cobalt ferrite. The optimized CoFe1.7In0.3O4/NiSe2 catalyst demonstrates remarkably low overpotentials of 335 mV to achieve current densities of 500 mA cm-2 (η500) for the oxygen evolution reaction, while maintaining complete stability over a 100-h chronocurrent measurement at 500 mA cm-2. In addition, the electrode also demonstrates excellent hydrogen evolution reaction performance and superior durability. This strategy can be extended to other spinel oxides to achieve stable oxygen evolution at a large current density.