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

• Published in: Journal of molecular liquids 2023-07, Vol.381, p.121831, Article 121831
• Main Authors: Nguyen, Thuy Thanh Doan, Nguyen, De, Vo, Phu Phong, Doan, Hoan Ngoc, Pham, Huu Thinh Nguyen, Hoang, Van Ha, Tien Le, Khoa, Kinashi, Kenji, Huynh, Vu Tan, Nguyen, Phuong Tuyet
• Format: Article
• Language: English
• Subjects: Photoreduction; Reduced graphene oxide (rGO); Statistical analysis; TiO2-rGO composite; XPS
• ISSN: 0167-7322; 1873-3166
• DOI: 10.1016/j.molliq.2023.121831

[Display omitted] •Photoreduction of graphene oxide by using TiO2 under UV irradiation.•Formation of TiO2–reduced graphene oxide composite.•ANOVA has been applied to explore the impact of solvents and UV–irradiation time.•Both solvents are good in removing oxygenated carbon groups (OCGs), but isopropanol causes less carbon defects than ethanol.•Long UV–irradiation time can lead to the re–introduction of OCGs and carbon defects of reduced graphene oxide. In this study, we performed the photoreduction of graphene oxide on TiO2′s 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 elucidate the scavenging effects of the solvents on the grafting of reduced graphene oxide (rGO) to the surface 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 > water. However, the appearance of carbon structural defects was observed by another rule: ethanol > water > 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.