Edge-doped Substituents As an Emerging Atomic-level Strategy for Enhancing M-N-C Single-atom Catalysts in Electrocatalysis of the ORR, OER, and HER

M-N-C single-atom catalysts (MN) have gained attention for their efficient use at the atomic level and adjustable properties in electrocatalytic reactions like the ORR, OER, and HER. Yet, understanding MN's activity origin and enhancing its performance remains challenging. Edge-doped substituents profoundly affect MN's activity, explored in this study by investigating their interaction with MN metal centers in ORR/OER/HER catalysis (Sub@MN, Sub = B, N, O, S, CH, NO, NH, OCH, SO; M = Fe, Co, Ni, Cu). The results show overpotential variations (0 V to 1.82 V) based on Sub and metal centers. S and SO groups optimize FeN for peak ORR activity (overpotential at 0.48 V) and reduce OER overpotentials for NiN (0.48 V and 0.44 V). N significantly reduces FeN's HER overpotential (0.09 V). Correlation analysis highlights the metal center's key role, with Δ and Δ showing mutual predictability ( = 0.92). proves a reliable predictor for Sub@CoN (Δ/Δ, = 0.96 and 0.72). Machine learning with the KNN model aids catalyst performance prediction ( = 0.955 and 0.943 for Δ/Δ), emphasizing M-O/M-H and the d band center as crucial factors. This study elucidates edge-doped substituents' pivotal role in MN activity modulation, offering insights for electrocatalyst design and optimization.