Theoretical Investigation of OH Adsorbed Activity of Single Atom‐Decorated Graphene by Density Functional Theory

Abstract

Based on first‐principles density functional theory (DFT) calculations, this work systematically investigates single‐atom catalysts (TM‐N 3 C, TM = Fe, Co, and Ni) for OER applications. Fe‐N 3 C is identified as a promising multifunctional catalyst. Electronic structure analysis reveals that the spin‐polarized density of states (DOS), particularly the minority‐spin d‐band center, is a key descriptor for catalytic performance. Among the studied systems, the Fe site exhibits the lowest activation energy (2.09 eV) for the H 2 O + * → *OH + H + + e − step, supported by transition state analysis showing its smaller imaginary frequency (159 cm − 1 ). COHP analysis of the ground state adsorption geometry shows that the Fe─O bond is shorter (1.58 Å) and has a more negative ICOHP value (–3.47) compared to Co (1.62 Å, –3.19) and Ni (1.65 Å, –2.97), indicating stronger Fe─O bonding. At the transition state, compared to the Ni─O and Co─O, the Fe─O bond becomes shorter (1.72 Å) with more negative ICOHP (–1.38), reflecting an earlier transition state and a lower barrier. These findings collectively demonstrate that the Fe‐site catalyst facilitates a more facile reaction pathway, providing atomic‐level insights for designing efficient electrocatalysts.