Sulfonated nano-diamonds composite sulfonated reduced graphene oxide: A efficient hydrophilic material for high performance supercapacitors

This paper reports a simple reaction for the synthesis of sulfonated reduced graphene oxide composite with sulfonated diamond nanoparticles, (rGO/ND)-SO3H. It is based on the reaction of a mixture of graphene oxide (GO) and hydroxylated nano-diamonds (ND-OH) with 1,3-propanesultone at 150 °C for 48 h. During this process, ND-OH were converted to sulfonated ND (ND-SO3H) and composite sulfonated rGO formed rGO-SO3H. The electrochemical performance of (rGO/ND)-SO3H in 1 M H2SO4 was compared with that of ND-SO3H, rGO-SO3H and rGO/ND. It could be shown that a maximum specific capacitance of 160.1 F g−1 can be achieved by (rGO/ND)-SO3H at 1 A g−1. 81.5% capacitance retention upon increasing the charge-discharge current density from 0.5 A g−1 to 15 A g−1 was observed, making the material a potent candidate for supercapacitor applications. The high electrochemical surface area and easy accessibility of electrolyte to the electrode material are believed to be the underlying reasons for the improved performance. Furthermore, as-fabricated (rGO/ND)-SO3H shows excellent cycling stability with more the 99.1% retention of the specific capacitance after 6000 galvanostatic charge-discharge cycles, making it a promising matrix for high performance electrochemical capacitors. [Display omitted] •The double-sulfonation treatment improves the hydrophilicity of the electrode.•The double-sulfonation treatment inhibits the stacking of graphene flake layers.•Nano-diamond can help to improve the rate capability of graphene.