Quantum capacitance of monolayer graphene influenced by both heteroatom and transition metal doping: Ab-initio study

Owing to substantial surface area and outstanding electronic conductivity, graphene has been widely accepted as a viable electrode material for supercapacitors. With the introduction of specific elemental dopants and utilisation of various morphological designs, it is possible to effectively modify the characteristics of graphene. Based on DFT computations, we examine the effects of nitrogen and iron doping, as well as the presence of monovacancy, on quantum capacitance (CQ), electronic structures, and the stability of graphene. Our findings reveal significant modifications in quantum capacitances of an electrode, attributable to monovacancy and doping. Based on our computations, it is indicated that introducing a monovacancy in monolayer graphene and incorporating N doping in the vicinity of monovacancy along with Fe doping could result in considerable alterations in CQ. Nevertheless, maintaining the stability of the structure can pose a challenge. When a monovacancy is combined with N doping in a single-layer structure, it can achieve a high CQ of approximately 90 μF/cm2 in a Fe-N3 system. The present research indicates the feasibility of enhancing the CQ of graphene-based electrodes by leveraging the combined effect of doping.