Exploring of the quantum capacitance of MoS2/graphene heterostructures for supercapacitor electrodes

Abstract

The geometry, electronic structures, quantum capacitance, and charge storage capacity of modified MoS2/graphene heterostructures were explored by density functional theory (DFT). The effect of introducing of vacancy (C-, Mo-, and S-vacancy) and transition-metal dopant (Sc, Ti, V, Cr, Mn, Fe, Co, and Ni) on the capacitance behavior of MoS2/graphene systems were also investigated. The results indicated that the presence of vacancy could improve the quantum capacitance (CQ) of MoS2/graphene heterostructure (MoS2/G), and the presence of Mo- and S-vacancy of MoS2-layer was more effective than that of C-vacancy of graphene. The electron density of states (DOS) around Fermi level suggested that the enhancement of CQ was attributed to the transition-metal dopants and C/Mo/S-atoms near vacancy. Our calculated results screened potential anode or cathode materials for high energy density supercapacitors, such as the maximum CQ of Fe-doped Mo-vacancy defected MoS2/G was 346.99 μF/cm2 at positive bias, which could be applied as effective anodes. It was hoped that the results could provide theoretical support to design supercapacitors with high capacitance.