Facile surfactant- and template-free synthesis and electrochemical properties of SnO2/graphene composites

In this work, we demonstrate a facile and green hydrothermal process without using any surfactant or template to synthesize SnO 2 nanoflowers (NFs)/graphene nanosheets (GNSs) composites as a high-performance electrode material for electric double layer capacitors (EDLCs). The crystal structure and morphology of the products were characterized by X-ray diffraction, scanning electron microscopy, and transition electron microscopy. The electrochemical properties were investigated by galvanostatic charge/discharge cycling and cycling voltammetry in a voltage range of −0.2–0.8 V. The results exhibit that the addition of GNSs did not change the tetragonal crystal structure of SnO 2 , and the GNSs were successfully coated on the flower-like surface of SnO 2 . The grain morphology of SnO 2 @GNSs composites has a flower-like appearance suggesting excellent electrochemical properties which were confirmed by electrochemical techniques. Compared with the GNSs, the SnO 2 @GNSs composites exhibit a high specific discharge capacitance of 126 F g −1 at 0.2 A g −1 and remains 98.2% after 2000 charge–discharge cycles. The combination of GNSs and SnO 2 could significantly improve the electrical conductivity, enhance the interactions between GNSs and SnO 2 NFs and provide more reaction sites, thereby resulting in improved electrochemical properties for the SnO 2 @GNSs composites in contrast with the pristine GNSs sample. The high specific capacity and long stability make the SnO 2 @GNSs nanocomposite as a electrode material for high-performance supercapacitors.