Breaking Sabatier's vertex via switching the oxygen adsorption configuration and reaction pathway on dual active sites for acidic oxygen reduction

Abstract

Single-atom catalysts are promising alternatives to platinum-based catalysts for the oxygen reduction reaction (ORR). However, the ORR process with multiple-step proton-coupled electron transfer occurring on a single-active site follows the linear scaling relation, making it difficult to break through Sabatier's limitation. Herein, we switch the ORR process from a sluggish associative pathway to a favorable dissociative one by constructing diatomic active sites with a Pt-like adsorption configuration, enabling the thermodynamic limit potential to break through Sabatier's vertex. Theoretical calculations and in situ characterization fully corroborate the Pt-like adsorption configuration of O₂ on Ru–Fe dual sites, which renders the direct cleavage of O–O bonds and avoids the formation of *OOH intermediates, thus boosting the ORR kinetics. Consequently, the well-designed Ru and Fe co-doped catalysts with dual active sites (Ru, Fe-NC DAS) deliver extraordinary ORR catalytic performance, as manifested by the high half-wave potential of 0.843 V in an acid medium and a record-breaking peak power density of 1.152 W cm⁻² in H₂/O₂ fuel cells, ranking at the top level of non-Pt catalysts reported so far. This work provides a new approach for designing highly efficient atomically dispersed catalysts and steering the corresponding catalytic reaction mechanisms.