Modulating the d-band center of boron doped single-atom sites to boost the oxygen reduction reaction

Abstract

The development of oxygen reduction reaction (ORR) catalysts with low overpotential is highly desirable but proves to be challenging. One promising way to improve the catalytic activity is to modulate the electronic structure of the catalyst; however, its impact on the intermediate adsorption kinetics remains poorly understood. Herein, a boron dopant was firstly reported to modulate the d-band center of a single-atom catalyst, enabling favorable adsorption kinetics and thus improved ORR performance. The optimized catalyst outperforms pure Fe–N–C and commercial Pt/C in a 0.1 M KOH medium, showing a half-wave potential of 0.933 V versus the reversible hydrogen electrode (vs. RHE) and ranking at the top of non-precious metal catalysts. First-principles calculations indicate the increased valence electrons and decreased magnetic moment of single-atom sites after B-doping. The modulated d-band center provides the system with favorable adsorption energy of oxygen and a much lower overpotential, thus greatly boosting the ORR performance.