Theoretical insights into oxygen reduction reaction catalyzed by phosphorus-doped divacancy C₃N nanosheet

The catalytic reduction of O₂ molecule into H₂O is investigated over a P-doped divacancy C₃N nanosheet (P-Dv-C₃N) by using density functional theory calculations. A negative formation energy is calculated for P-Dv-C₃N, suggesting that the introduction of a P atom into divacancy defective C₃N would be thermodynamically favorable. The oxygen reduction reaction (ORR) over P-Dv-C₃N would proceed via a 4e^- pathway (O₂ + 4H⁺ + 4e^-→ 2H₂O) at room temperature. The rate-determining step of the ORR on P-Dv-C₃N is O + H⁺ + e^- → OH which requires an activation energy of 1.21 eV. These results provide helpful insights into design novel metal-free catalysts to improve the kinetics of ORR in fuel cells.