Atomically Dispersed\nIridium on Polyimide Support\nfor Acidic Oxygen Evolution

Designing a high-performing iridium (Ir) single-atom\ncatalyst is\ndesired for acidic water electrolysis, which shows enormous potential\ngiven its high catalytic activity toward acidic oxygen evolution reaction\n(OER) with minimum usage of precious Ir metal. However, it still remains\na substantial challenge to stabilize the Ir single atoms during the\nOER operation without sacrificing the activity. Here, we report a\nhigh-performing OER catalyst by immobilizing Ir single atoms on a\npolyimide support, which exhibits a high mass activity on a carbon\npaper electrode while simultaneously achieving outstanding stability\nwith negligible decay for 360 h. The resulting electrode (denoted\nas Ir<sub>1</sub>–PI@CP) reaches a 49.7-fold improvement in\nmass activity compared to the counterpart electrode prepared without\npolyimide support. Both our experimental and theoretical results suggest\nthat, owing to the strong metal–support interactions, the polyimide\nsupport can enhance the Ir 5d states of Ir single atoms in Ir<sub>1</sub>–PI@CP, which can tailor the adsorption energies of\nintermediates and decrease the thermodynamic barrier at the rate-determining\nstep of the OER, but also facilitate the proton–electron-transfer\nprocess and improve the reaction kinetics. This work offers an alternative\navenue for developing single-atom catalysts with superior activity\nand durability toward various catalytic systems and beyond.