Electrochemically Modifying the Electronic Structure of IrO2 Nanoparticles for Overall Electrochemical Water Splitting with Extensive Adaptability

Designing the electrocatalysts that are stable and active for extensively adaptable water splitting is highly desirable for developing hydrogen based energy. IrO₂ is a promising and widely used catalyst for the oxygen evolution reaction in commercial applications, but is rarely used for the hydrogen evolution reaction (HER), due to the high Gibbs free energy for hydrogen adsorption (ΔG_H*). Herein, an approach to modify the electronic structure of IrO₂ via cyclic voltammetry is proposed. In this process, Ir(+4) is partially reduced and trace Pt is simultaneously deposited on IrO₂, which greatly lowers the ΔG_H* and thus accelerates the reaction kinetics. The as‐prepared Pt–IrO₂/CC with low noble metal loading (36.6 µg cm^?2_(Ir+Pt)) exhibits excellent HER activity with overpotentials of 5, 22, and 26 mV at 10 mA cm^?2 in 0.5 m H₂SO₄, 1 m KOH, and 1 m phosphate buffer solution, respectively, making it possible to organize an all‐IrO₂ based water electrolyzer. The Pt–IrO₂/CC||IrO₂/CC couple exhibits a promising activity and stability in pH‐universal conditions as well as natural seawater for H₂ production. Density function theory calculations reveal that the optimized electronic structure of IrO₂ balances the ΔG_H*, resulting in a much enhanced HER performance.