We studied the quantum capacitance, electric double layer capacitance, and total capacitance from quantum chemistry calculation and classical simulation. It was found that quantum capacitance is very important for single layer graphene and becomes less dominative as the layer number goes up. When the layer number goes up to 4, the total capacitance tends to converge due to the high quantum capacitance. In addition, we also studied the influence of nitrogen doping on the capacitance of single layer graphene electrode. Our results showed that nitrogen doping plays a very important role in quantum capacitance: (1) Graphitic and pyridinic nitrogens can greatly increase the quantum capacitance near Fermi level and the quantum capacitance enhancement is proportional to the doping concentration. (2) Pyrrolic nitrogen has a V-shape quantum capacitance, which is similar to graphene and in good agreement with experimental measurement. Our work on nitrogen doping revealed that nitrogen doping can increase total capacitance by increasing quantum capacitance, but this capacitance enhancement is limited by the existence of stable pyrrolic nitrogen.

Capacitance of graphene-based electrodes from combined first principles and classical simulations

251st National Meeting (2016)

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