Substitution and coordination effects of boron in Fe C and Fe N C single-atom catalysts for ORR: A DFT study

The development of durable and cost-effective cathode catalysts is critical to improving the oxygen reduction reaction (ORR) of fuel cells. The B-substituted Fe-based graphene single atom catalysts (SACs) were systematically analyzed using density functional theory (DFT). After analysis of the computational formation energy, 12 stable configurations are identified from 49 candidates. B-substituted in the first coordination sphere layer resulted in excessively strong adsorption of oxygen-containing intermediates, thereby increasing the overpotential. In contrast, the FeN 4 B 4 and FeN 4 B 5 catalysts, with B substitution in the second coordination sphere, exhibited low overpotentials of 0.32 V and 0.36 V, respectively. This enhancement is attributed to the B-atom-induced reconfiguration of the electronic structure and modulation of chemical bonding properties. • From 49 types of Fe-based single atom catalysts, 12 catalysts with ORR potential are selected by DFT. • Substituting C atom with B atom effectively regulates the catalysts coordination environment. • Substituting the second coordination sphere boosts ORR performance more than the first one. • B substitution C stabilizes single Fe sites, making FeN 4 B 4 and FeN 4 B 5 ORR performance stable.