Electronic structures and quantum capacitance of monolayer and multilayer graphenes influenced by Al, B, N and P doping, and monovacancy: Theoretical study

Graphene has been extensively explored as an electrode material in supercapacitors because of its large surface area and high electronic conductivity. By designing diverse morphologies and doping graphene with certain elements, the properties of graphene can be efficiently modified. We present the influence of Al, B, N and P doping, monovacancy and multilayer graphene structures on stability, electronic structures and quantum capacitance, by applying density functional theory calculations. The electrode quantum capacitances are substantially modified due to doping, the presence of monovacancy, and interaction between layers occurred in multilayer structures. Our calculations suggest that the monolayer graphene with monovacancy, the monolayer and multilayer graphene structures with nitrogen doped around the monovacancy, and multilayer graphene structure with aluminum doped could provide substantial change of quantum capacitance. However, the structure stability could be challenging. The interaction between layers could lower quantum capacitances compared to those of the monolayer structures with the same dopant elements. Moreover, the association of monovacancy and nitrogen doping of a single layer structure could lead to as high quantum capacitance as ∼80 μF/cm2. This work suggests the possibility to enhance quantum capacitance of the graphene-based electrodes using the combination effect of doping, vacancy defect and stacking layers.