γ-Ray Induced Reduction of Graphene Oxide in Aqueous Solution

Graphene, a one-atom-thick, two-dimensional (2D) sheet of carbon packed in a honeycomb lattice, has striking electronic, mechanical, and thermal properties. Reduced graphene oxide (RGO) and amine-Modified reduced graphene oxide (RGON) were obtained by gamma-ray induced reduction of a graphene oxide (GO) suspension in purified water and in a p-phenylene diamine (PPD) aqueous solution, respectively. The structures and elemental compositions of GO, RGO, and RGON were characterized by Fourier transform infrared (FIR) spectroscopy, X-ray photoelectron spectroscopy (XPS), Raman spectroscopy, X-ray diffraction (XRD), and thermogravimetric analysis (TGA). In addition, the electrical conductivities and hydrophilic properties were conducted with four-probe resistivity meter and contact angle measurements, respectively. The results reveal that GO can be well reduced by gamma-ray irradiation in either purified water or PPD aqueous solution. Furthermore, the electrical conductivities of obtained RGO and RGON are enhanced. The hydrophilicity of RGON is higher than that of RGO because the amine groups of PPD are modified on the surface of graphene nanosheets during the gamma-ray induced reduction. However, the conduction of electron on the surface of graphene can be inhibited by the modified amine groups. Therefore, the electrical conductivity of RGO is higher than that of RGON.