Thermal, photocatalytic, and antibacterial properties of rGO/TiO2/PVA and rGO/TiO2/PEG composites.

Graphene oxide (GO) was synthesized using the modified Hummer method. TiO2 nanoparticles, rGO/TiO2, and rGO/TiO2/polymer composites were synthesized using the sol–gel technique. Characterization of the prepared composites was carried out by using TGA, SEM–EDS, XRD, and FTIR. It was determined by SEM analysis that each composite showed a homogeneous distribution. The presence of carbon and oxygen for GO and rGO, the presence of titanium and oxygen for TiO2 particles, and the presence of carbon, titanium, and oxygen for rGO/TiO2 and rGO/TiO2/polymer composites have been proven by EDS analysis. The peaks of each composite have been demonstrated by XRD analysis where they show similar results with the materials that formed the composite. The presence of chemical bonds of Ti–O–Ti, C–O, C–OH, and Ti–O–C was proven with the FTIR results. According to TGA analysis, the initial weight loss occurred up to 100 °C due to the water molecules in the structure of rGO. Rapid weight loss occurred at the decomposition temperature of 480 °C. Above 530 °C, weight loss does not occur at temperatures, and rGO shows stability at 763 °C. From 763 to 900 °C, 95.65% of the rGO is completely decomposed. TiO2 nanoparticles showed weight loss at 80–115 °C. rGO/TiO2 composite showed weight loss at 110 °C and below, at 160–300 °C, and at 650 °C in total in three stages. rGO/TiO2/PVA composite showed weight loss at 40–110 °C, at 250–400 °C, and at 600 °C in total in three stages. rGO/TiO2/PEG composite showed weight loss at 28–196 °C, at 250–350 °C, and at 300 °C in total in three stages. TGA analysis results determined that TiO2 showed 0.43%, rGO/TiO2 14.21%, rGO/TiO2/PVA 71.06% and rGO/TiO2/PEG composite 90.56% weight loss. Acid Black I dye and E.coli bacteria were used to determine the photocatalytic and antibacterial activities of the composites, respectively. The rGO/TiO2/PEG composite showed the best result with 78.85% dye decomposition. And also the rGO/TiO2/PVA composite showed the best result with 78.6% bacteria removal compared to other synthesized composites. Hardness measurements showed that the rGO/TiO2 structure has the best hardness value with 74.34 HV due to the covalent carbon bonds in the rGO structure. [ABSTRACT FROM AUTHOR]