Ir–Co3S4/CoOxHy Heterojunction Enables Efficient Alkaline Oxygen Evolution through Binuclear Ir–Co Active Sites

Developing efficient and stable oxygen evolution reaction (OER) electrocatalysts is vital to advancing the expansion of water-splitting for green hydrogen production. However, the high overpotential and unsatisfactory stability of electrocatalysts have been significant obstacles. Herein, hydrothermal and cathodic electrodeposition are utilized to prepare an atomically dispersed Ir-doped Co₃S₄ electrocatalyst (Ir–Co₃S₄) as precatalysts, exhibiting a record-low overpotential (158 mV at 10 mA cm^–2) and ultrahigh stability (1000 h at 100 mA cm^–2) in 1 M KOH after activation, making it one of the best-performing OER anodes. In situ characterizations and theoretical calculations demonstrated that Ir–Co₃S₄ undergoes a precatalytic evolution of sulfur–oxygen exchange to form a dual-anionic coordination environment, which is conducive to enhancing the activity of CoOOH formation at operating voltages. Ir–Co dual active sites in Ir–Co₃S₄/CoO_xH_y could trigger the OER via a kinetically advantageous oxide coupling mechanism (OCM). Furthermore, in conjunction with the Raman findings, the molecular dynamics simulations demonstrate that the SO₄^2– generated by the electrode exerts a role in repelling Cl^– through dense coverage and electrostatic repulsion, demonstrating the potential being used in saline-alkaline water splitting. This work proposes combining single noble metal atoms with economically efficient metal sulfide catalysts and presents a rational design approach for hydrogen production electrocatalysts.