Potassium citrate mediated self-restacking of graphene oxide to highly-microporous carbon nanosheets for high-performances supercapacitor

Abstract

Because of the superior hydrophilicity of graphene oxide (GO) originated from its rich oxygenic species, assembly of graphene GO to a porous carbons have long been a hot-topic, however, most of them focus on preventing the occurrence of restacking of GO so that an open-accessed nanostructure could be attained. Herein, at a just the opposite way, we developed a strategy using potassium citrate mediated evaporation induced self-restacking of GO to fabricate porous carbon nanosheets. The resultant products (PCG-x) owns a nanosheet morphology, richness in microporosity, abundant oxygenic functionalites (8.96–9.49 atom%), moderate surface area (683–833 m2/g) and high packing density. Systematically electrochemical investigation show that the resultant PCG-n fabricated with optimal potassium citrate/GO ratio based electrode and devices attains superior both gravimetric and volumetric supercapacitor performances to its counterparts of rGO and PCG based ones due to the features of high microporosity ratio, moderate oxygenic functionalities and high packing density. Concerning PCG-n based device, a considerable energy density of 33 Wh/kg@900 W/kg (34.7 Wh/L@945 W/L) was achieved, the value is higher than that of rGO, PCG and some recently reported carbon based supercapacitors, offering great potential for energy storage.