▎ 摘　　要

Calculations based on density functional theory are performed to explore the effect of the phosphorus dopants and their oxygenation on the quantum capacitance of single- and double-vacancy graphene in the voltage range from -1.5 to +1.5 V. It is found that these modified graphenes have improved quantum capacitance, and can store more charges compared to the pristine graphene. The findings can be used as a guidance for the rational design of P-doped graphene as an electrode material of asymmetric supercapacitors with high energy density.