Low temperature reduction of graphene oxide film by ammonia solution and its application for high-performance supercapacitors

Here we demonstrate that graphene oxide (GO) film on Ni foam can be doped with nitrogen atoms and reduced directly at a lower temperature of 90 °C using ammonia solution as reducing agent and nitrogen source. The reduction and nitrogen doping of GO occur simultaneously when GO film on Ni foam is immersed into ammonia solution. The nitrogen doping can be realised and the content of N in graphene film turns out to be rather good as high as 3.60%. When used as binder-free electrode, the resulting graphene film on Ni foam delivers a gravimetric capacitance of 230 F g⁻¹. It also exhibites relatively an outstanding rate capability of 164 F g⁻¹ at 83.3 A g⁻¹ and better cycle stability that capacitance retention maintains at 96.7% of its initial capacitance capacitance after 2000 cycles. The method also provides a universal route for preparing a binder-free graphene-based electrode.