Boron-Doped C3N Monolayer as a Promising Metal-Free Oxygen Reduction Reaction Catalyst: A Theoretical Insight

Active metal-free catalysts for the oxygen reduction reaction (ORR) are extremely desired for the renewable energy technology. In this study, the ORR on the B-doped C3N monolayer in the acid environment has been investigated by using the first-principle calculations. It is found that the formation of the B-doped C3N monolayer is highly exothermic. The ORR on the B-doped C3N monolayer proceeds through the four-electron pathway. For the doped C3N monolayer with B replacing N, the ORR prefers to proceed by first forming an OOH intermediate and then reducing OOH to OH + OH. The reduction of OH + OH to H2O + OH is the rate-determining step with an energy barrier of 1.05 eV, and the formation of the second H2O is the potential-determining step with an overpotential of 0.60 V. However, the doped C3N monolayer with B replacing C has a low catalytic activity toward the ORR compared with the former, the underlying mechanism for which has been explored based on the electronic structure analysis. Our study suggests that B-doped C3N nanostructures hold great potential as efficient metal-free catalysts for the ORR, which deserve further experimental investigation.