The roles of ethanol and isopropanol as hole scavengers in the photoreduction reaction of graphene oxide by TiO2: A competition of oxygenated groups removal and carbon defects invasion

In this study, we performed the photoreduction of graphene oxide on TiO02s surface with three solvents ethanol, isopropanol, and water under ultraviolet irradiation. The materials were assessed by different techniques such as X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), Fourier transform infrared (FTIR), Raman spectroscopy, and Field-emission Scanning electron microscope (FE-SEM) to elu-cidate the scavenging effects of the solvents on the grafting of reduced graphene oxide (rGO) to the sur-face of TiO2. The photoreduction process was established chemical bondings between rGO and TiO2. Using alcohols as solvents, the photoreduction efficiency was significantly improved compared with water solvent, signifying by the lower amount of C-O than C-C bonds determined by X-ray photoelectron spectroscopy (XPS). As a result, isopropanol showed better scavenging behaviors than that of ethanol. The photo-reduced graphene oxide products also possessed fewer carbon defects while using isopropanol than water or ethanol. The results confirmed the scavenging effects of common alcohols by integrating them with statistical analysis (ANOVA, etc.). Moreover, we also showed that the use of alcohols is highly effective in cutting carbon groups containing oxygen in the following order: isopropanol > ethanol > wa-ter. However, the appearance of carbon structural defects was observed by another rule: ethanol > wa-ter > isopropanol. This work aimed to indicate the pros and cons when dealing with different solvents and helped us to choose the optimal medium for the photoreduction of graphene oxide grafted on the surface of TiO2. (c) 2023 Elsevier B.V. All rights reserved.