Layered inorganic–organic hybrid material based on reduced graphene oxide and α-Ni(OH)₂ for high performance supercapacitor electrodes

Abstract

We describe a facile one-step strategy for the synthesis of a novel layered hybrid material of reduced graphene oxide (rGO) and α-Ni(OH)₂by non-hydrothermal route and the supercapacitive performance of the material. The hybrid material rGO/α-Ni(OH)₂was synthesized using glucose as a templating agent for the growth of layered α-Ni(OH)₂and a reducing agent for the reduction of graphene oxide (GO). The templating agent partially reduces GO to rGO and assists the growth of α-Ni(OH)₂layers in between the rGO sheets. The electron microscopy measurements show the stacking of layered α-Ni(OH)₂over rGO sheets. The activity of the hybrid material was evaluated by voltammetric, electrochemical impedance and charge–discharge measurements in alkaline pH in terms of specific capacitance, internal resistance and capacitance retention. The hybrid material has superior performance, which is comparable to rGO, free α-Ni(OH)₂and the physical mixture of rGO and free α-Ni(OH)2. A high specific capacitance of 1671.67 F g^-1 was obtained at a current density of 1 Ag^-1. The hybrid material retains 81% of its initial capacitance after 2000 continuous charge–discharge cycles. The large surface area and high electronic conductivity of the hybrid material favor a facile charge transport, whereas the layer structure ensures the easy diffusion of electrolytes ions and enhances the overall performance. An asymmetric supercapacitor device was made by pairing the hybrid material with rGO, and it delivers a high energy density of 42.67 W h kg^-1 at a power density of 0.4 kW kg^-1.