Effects of the N/S codoping configuration and ternary doping on the quantum capacitance of graphene

Heteroatom doping is considered to be a highly effective approach for changing the electronic properties of graphene. However, the effects of the doping mode and site have not been investigated in detail. We explored the effect of the N/S codoping configuration and ternary doping with other elements on the quantum capacitance of graphene. It was found that at the same doping concentration, the Fermi levels are both shifted to the conduction band for chain doping and distributed doping, enhancing the electronic properties of graphene and effectively improving the quantum capacitance. The newly introduced heteroatoms contribute less to the obtained quantum capacitance than nitrogen and sulfur. N/S codoping is still a relatively effective doping method, and the optimal quantum capacitance was obtained for the nitrogen to sulfur ratio of 1:2. This work sheds light on the effect of the N/S codoping on the carbon electrode and suggests an effective approach for optimizing the quantum capacitance.