Advanced Powder Technology, Vol.30, No.1, 18-22, 2019
pH controlled synthesis of porous graphene sphere and application to supercapacitors
Graphene (GR) has excellent physical and chemical properties, making it promising for application in supercapacitors. In this study, we report the synthesis of spherical GR (SGR) composed of tens of GR sheets and its application in supercapacitors. Graphene oxide (GO) was first reduced in the liquid phase by using L-ascorbic acid (L-AA), an environmentally friendly reducing agent, and then SGR was prepared using the reduced GO colloid by aerosol spray drying. The reduction of GO in the liquid phase was completed in 1 h. The SGR fabricated by the aerosol process ranged from 2 to 4 mu m in diameter. The as-prepared SGR fabricated from GO at pH 2 showed a densely packed spherical morphology and porous structure with a specific surface area of 150 m(2)/g. The SGR fabricated from the GO colloid at pH 10 showed an improved specific surface area (216 m(2)/g) and a higher specific capacitance (182 F/g) than the SGR fabricated at pH 2. Considering the environmentally friendly process, the as-prepared SGR is a highly promising material for supercapacitors. (C) 2018 The Society of Powder Technology Japan. Published by Elsevier B.V. and The Society of Powder Technology Japan.