Ultra-simple and green two-step synthesis of sodium anthraquinone-2-sulfonate composite graphene (AQS/rGO) hydrogels for supercapacitor electrode materials

As a kind of cheap and easily available organic molecular with Faradic redox activity, quinones can well combined with carbon-materials by non-covalent π–π conjugation and remedy its shortcomings possessing relatively low specific capacitance. However, in previous studies, the combination of quinones and carbon-based materials often requires toxic organic solvent or high energy-consuming and interminable process, greatly hindering their practical application. Here we use water-soluble sodium anthraquinone-2-sulfonate (AQS) and graphene oxide (GO) solution as raw materials to directly obtain AQS composite reduced GO (AQS/rGO) hydrogels by chemical reduction, the whole process of which is performed at relatively low temperature and normal pressure, and only takes a short time, resulting in great promotion in sustainability and efficiency. The AQS/rGO hydrogel exhibiting a high specific capacitance of 387.43 F g−1 at 1 A g−1 and an excellent cycling stability of 91.11% after 10000 cycles at 10 A g−1, has a prodigious improvement for the pure graphene in all aspects. Besides, the maximum energy density of the asymmetric supercapacitor assembled by AQS/rGO-1 hydrogel reaches 15.98 W h kg−1 at the power density of 325.02 W kg−1. This work provide a new idea for the green and efficient preparation of graphene organic quinones composite and has an important significance for its practical application.