Synergistic spin–valence catalysis mechanism in oxygen reduction reactions on Fe–N–C single-atom catalysts

Abstract

The spin and valence states of active sites play a direct and crucial role in the activity of transition-metal-based catalysts. However, modulating the spin and valence states based on the synergistic spin–valence effect to manipulate catalytic activity has been scarcely explored. Herein, we carried out density functional theory calculations on typical Fe–N–C single-atom catalysts (SACs) to elucidate the crucial role of the synergy of spin and valence in determining their oxygen reduction reaction (ORR) activity. The underlying synergistic spin–valence catalysis mechanism (SSVCM) can coordinate multiple spin and valence states involved in the reaction, enabling the optimal activity to be achieved by delicately designing the reaction pathway. Modulating the spin and valence state promotes the ORR onset potential from 0.73 V to 1.01 V at pH = 1 and from 0.70 V to 0.95 V at pH = 13, showing great potential for designing ORR catalysts with superior activity. These findings provide critical information on the ORR activity of Fe–N–C SACs.