Preparation and supercapacitive properties of phosphorus-doped reduced graphene oxide hydrogel

Heteroatom doping is considered to be a promising way to improve the performance of graphene-based supercapacitors. It is important to research that the roles of the heteroatom sources and contents in capacitor performance. In this study, phosphorus-doped three-dimensional reduced graphene oxide hydrogels(RGP) were prepared by one-step hydrothermal method with phytic acid, phosphoric acid, potassium dihydrogen phosphate as phosphorus sources, respectively. The microstructure and morphology of the as-produced graphene were characterized by means of various techniques. The effects of phosphorus dopants and phosphorus contents in the graphene on the electrochemical performances of the prepared products were evaluated. The results show that all three phosphorus sources doped graphene exhibit excellent electrochemical properties. When the phytic acid is used as the dopant(phosphorus content is 0.94%), the electrochemical performance was the best among the P-doped graphene (388.5 F g(-1) at 1 mA cm(-2) current density in 1 mol L-1 H2SO4 electrolyte. After 10000 cycles, the specific capacitance retention rate is 99.0%). This is attributed to the fact that P-doped reduced graphene oxide(RGO)with two bonding states of P-C and P-O can effectively improve the pseudo capacitance of RGO, and high proportion of P-O and appreciate amount of P doping presented the excellent electrochemical performance. The study illustrated that phosphorus doping can effectively control the structure of graphene sheet and has high potential for use in low cost energy storage devices. (C) 2019 Elsevier Ltd. All rights reserved.