Chapter 5 - Green Synthesis for Advanced Materials of Graphene Oxide (GO) with ZnO for Enhanced Photocatalytic Activity at Room Temperature

Abstract

Graphene oxide (GO) synthesized by simple green wet chemical process in a suspension of ZnO (zinc oxide) nanocrystals to fabricate the ethylene glycol performs as a reducer and modifying agent in the system. The as-obtained products were characterized by X-ray diffraction (XRD), Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), high-resolution transmission electron microscopy (HRTEM), energy-dispersive X-ray spectroscopy (EDS), cyclic voltammetry (CV), photoluminescence (PL), and photocatalytic studies. XRD studies indicate that the GO nanosheet has the same crystal structure found in the hexagonal form of ZnO. The enhanced Raman spectrum of 2-D bands confirmed the formation of single-layer GOs. The gradual photocatalytic reduction of the GO nanosheet in the GO:ZnO suspension of ethanol was studied by using XPS. The nanoscale structures were observed and confirmed using HRTEM. The elemental composition, especially the Al concentration and distribution them with a various number of layers were determined from EDS. The current-voltage measurements showed that electrical sheets resistance of the GO:ZnO nanosheet decreased by increasing the irradiation exposure time. PL properties of GO:ZnO nanosheet were found to be dependent on the growth condition, and the resultant morphology revealed that GO nanosheets were highly transparent in the visible region. The photocatalytic performance of GO:ZnO nanocomposites was performed under UV irradiation. Therefore, the ZnO nanocrystals in the GO:ZnO composite could be applied in gradual chemical reduction and consequently tuning the electrical conductivity of the GO nanosheet.