Structural and optical properties of thermally reduced graphene oxide for energy devices

Natural intercalation of the graphite oxide, obtained as a product of Hummer's method, via ultra-sonication of water dispersed graphite oxide has been carried out to obtain graphene oxide (GO) and thermally reduced graphene oxide (RGO). Here we report the effect of metallic nitrate on the oxidation properties of graphite and then formation of metallic oxide (MO) composites with GO and RGO for the first time. We observed a change in the efficiency of the oxidation process as we replaced the conventionally used sodium nitrate with that of nickel nitrate Ni(NO₃)₂, cadmium nitrate Cd(NO₃)₂, and zinc nitrate Zn(NO₃)₂. The structural properties were investigated by x-ray diffraction and observed the successful formation of composite of MO-GO and MO-RGO (M = Zn, Cd, Ni). We sought to study the effect on the oxidation process through optical characterization via UV-Vis spectroscopy and Fourier Transform Infrared (FTIR) spectroscopy. Moreover, Thermo Gravimetric Analysis (TGA) was carried out to confirm >90% weight loss in each process thus proving the reliability of the oxidation cycles. We have found that the nature of the oxidation process of graphite powder and its optical and electrochemical characteristics can be tuned by replacing the sodium nitrate (NaNO₃) by other metallic nitrates as Cd(NO₃)₂, Ni(NO₃)₂, and Zn(NO₃)₂. On the basis of obtained results, the synthesized GO and RGO may be expected as a promising material in antibacterial activity and in electrodes fabrication for energy devices such as solar cell, fuel cell, and super capacitors.