Dual active site-mediated Ir single-atom-doped RuO2 catalysts for highly efficient and stable water splitting

Abstract

The electronic structure modulation through heterogeneous single-atom doping is an effective strategy to improve electrocatalysis performance of catalysts. Here, Ir single-atom doped RuO₂ (Ir_SA/RuO₂) is constructed by substituting Ru sites with mono-disperse Ir atoms in RuO₂ crystals. The Ir_SA/RuO₂-850 catalyst shows excellent activity for the hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) in alkaline media, with overpotentials of only 37 and 234 mV respectively, at a current density of 10 mA cm⁻², lower than that of commercial Pt/C (39 mV-HER) and RuO₂ (295 mV-OER). Notably, no significant degradation occurs during the 1000 h HER stability test at 500 mA cm⁻². Furthermore, Ir_SA/RuO₂-850 also demonstrates superior catalytic activity and stability in acidic media. Theoretical calculations show that the interaction between Ir and RuO₂ modulates the electronic structure of both Ru and Ir sites, resulting in the lowest reaction energy barriers of Ru and Ir sites for the HER and OER, respectively, which thermodynamically explains the enhancement of the catalytic activity. Besides, the introduction of Ir atoms also enhances the demetallation energy of Ru atoms and strengthens the structural stability of the crystal, leading to the improved stability of the catalyst. This work provides an effective strategy for construction of high-performing catalysts by precisely controlling the electronic structure and active sites of polymetal atoms.