▎ 摘　　要

Recent studies suggest that the carbon-alloy catalyst with doped nitrogen may be a powerful candidate for cathode catalyst of fuel cell. In this paper, we aim to clarify the microscopic mechanisms of the enhancement in the catalyst activity caused by nitrogen doping using a simple graphene cluster model. Our analysis is based on the density-functional electronic-structure calculations. We analyze modifications in the electronic structures and the energetical stability for some different configurations of N doping. We extend the analysis to the case of codoping of nitrogen and boron and propose two possible scenarios explaining the further enhancement of catalytic activity by N and B codoping.