A novel strategy to decorate Ni(OH)2 micro flowers on highly exfoliated rGO sheets supported by 3D-Ni foam architecture as binder free supercapacitive electrode

Abstract

The reduced graphene oxide (rGO) has been widely studied as a supercapacitive electrode material due to its distinctive properties, including high specific surface area and electronic conductivity. However, the tendency of re-stacking limits its efficiency due to a reduction in specific surface area. Therefore, a highly efficient novel strategy “dipping and drying technique” has been introduced in this work to develop highly exfoliated rGO sheets on the porous Ni foam (NF) structure. For further enhancement in the electrochemical performance of rGO@NF based electrode, Ni(OH)2 micro-flowers have been anchored on the highly exfoliated graphene sheets using a facile and environment friendly hydrothermal approach. Thus, the Ni(OH)2/rGO@NF exhibits superior electrochemical performance, showcasing the specific capacitance of 4446 F/g at a current density of 1 A/g with the retention capacity of 89% during 10 000 cycles of charging–discharging at 50 A/g current density. Interestingly, the Ni(OH)2/rGO@NF electrode maintains a high specific capacitance of 1077 F/g even at a very high current density of 100 A/g. Furthermore, the diffusive capacitance dominates at a lower scan rate, while the surface capacitance dominates at a higher scan rate, determined through Dunn's method. Thus, the highly exfoliated rGO nanosheets decorated with hierarchically grown Ni(OH)2 micro-flowers supported by Ni foam demonstrate very impressive specific capacitance, offering a promising strategy.