Theoretical study on B-doped FeN4 catalyst for potential-dependent oxygen reduction reaction.

Electrochemical reactions mostly take place at a constant potential, but traditional DFT calculations operate at a neutral charge state. In order to really model experimental conditions, we developed a fixed-potential simulation framework via the iterated optimization and self-consistence of the required Fermi level. The B-doped graphene-based FeN4 sites for oxygen reduction reaction were chosen as the model to evaluate the accuracy of the fixed-potential simulation. The results demonstrate that *OH hydrogenation gets facile while O2 adsorption or hydrogenation becomes thermodynamically unfavorable due to the lower d-band center of Fe atoms in the constant potential state than the neutral charge state. The ORR overpotential obtained at a constant potential of 1.23 V agrees well with the experimental values. This work indicates that the fixed-potential simulation can provide a reasonable and accurate description on electrochemical reactions.