Activation of iridium site based on IrO2 catalysts towards highly stable PEM water electrolyzer

Abstract

The exploitation of anode electrocatalysts with high activity and stability remains an enormous challenge in proton exchange membrane (PEM) water electrolyzer. Here we doped Mn to activate Ir site in IrO₂ through the molten salt sealing method, and the optimized Mn_0.1Ir_0.9O₂ exhibited superior OER performance. Mn doping optimized the electronic structure and dominant crystal planes of IrO₂, as evidenced by our complementary characterizations. Impressively, the Mn_0.1Ir_0.9O₂ exhibits superior performance in the PEM water electrolyzer, only requiring 1.79 V to attain 1 A cm⁻² and offering long-term stability over 1200 h (attenuated only 17.5 μV h⁻¹ compared to 1.27 mV/h for the original sample). DFT calculation shows Mn doping could activate Ir site, thus reducing the energy barrier of the rate-determining step for promoting OER. This work provides a strategy to design high-tolerance catalysts for the PEM water electrolyzer in actual working conditions.