Structural-Insensitive Descriptors Ns,p Based on M-N4-OH Active Entity for Predicting and Enhancing ORR Activity in 3d Transition Metal Catalysts

Abstract

The development of high-performance ORR catalysts is challenged by the understanding how the delocalized electrons in s- and p-orbitals influence oxygen intermediate adsorption and overall catalytic performance. To address these challenges, the from active unit to bulk catalyst (FAUC) design strategy is employed to investigate the roles of s- and p-orbitals in ORR activity. Specifically, six M-N₄-OH (M = V, Cr, Mn, Fe, Co, and Ni) catalyst systems are constructed and analyzed using density functional theory (DFT), this study reveals that, compared to d-orbitals, the delocalized electrons in the s- and p-orbitals (N_s,p) exhibit a significant volcano relationship with ORR activity. This superior predictive capability arises from the weaker dependence of s- and p-orbitals on the local coordination environment. Additionally, a structure-activity relationship is established where shortening M─O and M─N bond lengths significantly increases N_s,p. Through modification strategies such as doping and loading, the Co─N bond lengths are regulated in Co-N₄-OH-C, resulting in shorter bonds and increased N_s,p, which shifted ORR catalytic activity closer to the volcano peak. These findings validate the N_s,p descriptor's rationality and universality across various 3d transition metals, providing new insights for the design of high-performance ORR catalysts.