Porous graphene oxide nanosheets warped by Ni(OH)2 platelets as an efficient binder-free electrode material for supercapacitors

Abstract

This article describes synthesis of the nickel hydroxide nanostructures (Ni(OH)2)@porous reduced graphene oxide (p-RGO) on 3-D nickel foam (NF) through a cost-effective one-step electrochemical strategy. This method composed of electrophoretic deposition of porous RGO plates and in situ formation of hydroxide nanostructures onto NF electrode. For comparison, the pristine Ni(OH)2/NF electrode was also fabricated via the similar method. The prepared nano-composite structure showed high surface area of 269.3 m2 g–1 with mesoporous texture and mean pore diameter of 3.58 nm, where the pure Ni hydroxide exhibited only surface area of 73.5 m2 g–1 and pore diameter of 2.75 nm. Both prepared samples were characterized via XRD, IR, FE-SEM, Raman, BET, TGA/DSC and TEM analyses. The nickel hydroxide@p-RGO composite deposited onto NF electrode has high specific capacitances as well as high electrical conductivity, where it delivered higher capacity of 1792 F g–1 at a current load of 2 A g–1 when compared with the Ni(OH)2 electrode (1175 F g–1 at the same current density), which nearly 65 % increment in capacity was observed. The composite material exhibited an outstanding capacity retention of ∼95.3 % and 87.6 % after 4000 cycles at the current densities of 1 and 7 A g–1, respectively. This methodology provides a feasible route for preparation of the metal hydroxide/graphene hybrid materials for electrochemical energy storage applications.