Reagent-adaptive active site switching on the IrOx/Ni(OH)2 catalyst

Abstract

A significant challenge is to develop smart catalysts that can adapt in real time to complex reaction environments. Here, we report a bifunctional catalyst, IrO_x/Ni(OH)₂ assembly, that can switch between the urea oxidation reaction (UOR) and the oxygen evolution reaction (OER) depending on the reagent coverage on the catalyst. This switch is achieved by altering the electron transfer path in the Ir–O–Ni configuration. At a critical concentration of urea, the electron transfer shifts from the Ir site to the Ni site, resulting in the switch from the OER to the UOR. This reagent-adaptive electron transfer path switching is facilitated by local charge redistribution with increasing reagent coverage. The catalyst exhibits a low onset potential of 1.42 V vs. reversible hydrogen electrode (RHE) for the OER and 1.32 V vs. RHE for the UOR, and 200 hours of stability at 10 mA cm⁻² for both the OER and UOR. This reagent-adaptive active center switching makes the catalyst useful for hydrogen production coupled with environmental purification, providing a promising approach for efficient and adaptable catalysis.