Achieving the selectivity of the oxygen reduction reaction by regulating electron spin states and active centers on Fe–Mn–N6–C dual-atom catalysts†

Abstract

The relationship between the catalytic activity and selectivity of transition metal-based atom-dispersed catalysts and their spin states is a fundamental yet intricate aspect of their functionality. Despite considerable research efforts, elucidating the precise correlation between spin dynamics and catalytic performance remains elusive. Controlling the spin state and active centers of Fe–Mn–N₆–C catalysts through density functional theory (DFT) enables precise manipulation of oxygen reduction reaction (ORR) selectivity. By designating either a single Fe or Mn atom as the active site, the reaction predominantly follows a 2-electron (2e⁻) pathway, yielding high selectivity for hydrogen peroxide (H₂O₂). Conversely, dual Fe and Mn active sites favor a 4-electron (4e⁻) pathway, promoting water (H₂O) production due to a reduced energy barrier for O–O bond dissociation, 0.18 eV. The differential change in the electron spin magnetic moment between 4e⁻ and 2e⁻ pathways serves as a critical descriptor for selectivity assessment. This method allows for the attainment of highly selective and efficient ORR by adeptly managing single and bimetallic active centers alongside their spin states. This insight enhances our understanding of spin-catalyst correlations and offers a theoretical foundation for developing catalysts with broad applications, underscoring the pivotal role of spin manipulation in catalytic performance optimization.