Fabrication of graphene supported binary nanohybrid with multiple approaches for electrochemical energy storage applications

Abstract

In the current study, we have fabricated Mn-doped Co3O4 nanoparticles (Mn.Co3O4 NPs) and their binary nanohybrid with r-GO nanosheets (Mn.Co3O4/r-GO) and decorated it directly on the nickel foam (NF) via a single-step hydrothermal method. The Mn.Co3O4/r-GO nanohybrid exhibits excellent electrical conductivity (1.84 × 104 Sm−1) and a higher BET surface area (147 m2 g−1). The Mn.Co3O4/r-GO sample electrode shows an outstanding electrochemical activity and exhibits a gravimetric capacitance up to 932 Fg−1 @ 1 Ag−1. On increasing the current density from 1 to 5 Ag−1, the nanohybrid electrode retains 84.4% of its original capacitance (at 1 Ag−1), indicating its excellent rate capability. Moreover, the nanohybrid electrode reveals exceptional cycling stability as it lost just 7.3% of its original capacitance (at the 1st cycle) after 5000-cycling experiments. The tremendous electrochemical activity of the fabricated nanohybrid can be ascribed to the synergistic effect between the good crystallinity of its Mn.Co3O4 NPs and excellent conductivity of its r-GO nanosheets. The 3D nanostructure of the Mn.Co3O4/r-GO nanohybrid decorated directly on the NF shorter the ion diffusion path and exposes more active sites to achieve the superior gravimetric capacitance and higher rate capability. This study may offer the use of multi-approaches to engineer the novel 3D nanostructured electrode materials for electrochemical capacitors with excellent cyclic stability, good rate capability, and higher gravimetric capacitance.