Controllable Preparation And Energy Storage Property Of Reduced Graphene Oxide

Graphene fabricated by chemical oxidation reduction method has attracted broad attention due to its advantages of low cost, and approachable scale production. The quality of graphene oxide (GO) plays an essential effect on the final product of reduced graphene oxide (rGO), since it is the precursor of rGO. The related functional materials based on reduced graphene oxide possess excellent physical and chemical properties, which have promising application in bio-medicine, electrochemical energy storage and sensing with high researching value.Here, through the Modified Hummers Method, the temperature and holding time of oxidation reaction during medium temperature process and the duration of high temperature process were controlled to compare the oxidation degree of graphite for controllable preparation of graphene oxide with different chemical properties. In addition, the graphene paper based on graphene oxide was prepared via vacuum filtration method and reduced by sodium ascorbate, applied to electrochemical capacitor. The FTIR Spectroscopy, XRD, Raman spectroscopy were used to analyze the chemical structures of GO. The SEM was used to characterize the microstructure of graphene paper. Meanwhile, the electrochemical energy storage properties of graphene paper as the capacitor electrode were also studied. Furthermore, we develop a preparation method of porous graphene electrode materials through simply immersing the Cu foil into the graphene oxide (GO) aqueous solution, holding for 24 hours, and then conducting a thermal shock to the layered-structure GO paper self-assembled on Cu foil under nitrogen flowing. Based on graphene aerogel, we put the 3D graphene into the tube furnace mixed with KOH at 800? to obtain the new 3D graphene material of modified structure. Finally, we explored the lithium ion batteries properties of this modified graphene as anode material compared with SnO2/graphene.As the results show, the graphene capacitor based on this low-cost new method under mild conditions growing on the Cu foil showed typical non-Faradaic characteristics of electrical double layer structure as well as high coulombic efficiency, which had a stable capacitance of 47.5F g-1 at the current density of 0.5A g-1.The as-prepared porous graphene paper after thermal shock exhibited a large specific capacitance of?100 F g-1 at the scan rate of 100 mV s-1 and a higher capacitance retention rate of above 100% with high stability and purity without any residual chemical reagents compared with the other two planner graphene paper electrodes reduced by sodium ascorbate and hydroiodic acid. As the electrodes of lithium ion batteries, SnO2/graphene compound exhibits superior specific capacitance as 1263.6 mAh g-1 at the first cycle, though the three dimensional graphene electrode has stably higher specific capacitance as 100 mAh g-1 after degradation. In addition, the 3 dimensional (3D) graphene aerogel can be prepared by hydrothermal method to fabricate the porous structure.