Fabricating nano-IrO2@amorphous Ir-MOF composites for efficient overall water splitting: a one-pot solvothermal approach

Abstract

Water splitting by electrolysis is a promising technology that can address rising energy demands and environmental pollution. However, the oxygen evolution reaction (OER), as one half-cell reaction of water splitting, always suffers from slow kinetics and a large overpotential due to the four proton-coupled electron transfer process, and dominates the overall process efficiency. IrO₂ is a promising and widely used catalyst for the OER in commercial applications. Herein, we obtained low-crystalline nano-IrO₂ particles confined in an amorphous Ir-based MOF (IrO₂@Ir-MOF) through a simple solvothermal reaction, in which ultrafine IrO₂ particles are uniformly distributed in the Ir-MOF skeleton. The fabricated IrO₂@Ir-MOF-ppy electrode exhibits excellent OER activity with an overpotential of 207 mV, to achieve a current density of 10 mA cm⁻² in 1 M KOH solution, outperforming most previously reported OER catalysts. The IrO₂@Ir-MOF‖IrO₂@Ir-MOF couple exhibits promising activity and stability for the overall water splitting reaction in 1 M KOH (1.53 V).