Photocatalytic degradation is a promising method for the removal of organic pollutants from mixtures. When semiconductors receive energy which is equal to or higher than their band gap energy, electrons are excited from the valence band to the conduction band, leaving a hole in the valence band. The electron-hole pair can react with oxygen to form reactive oxygen species (ROS), which are then capable of degrading organic molecules. Furthermore, graphene is an allotrope of carbon that forms flat structures with large surface areas. However, it can also be combined with oxygen functional groups to produce Graphene Oxide (GO). By combining the photocatalytic properties found in semiconductors, such as TiO2, with the large surface area property and oxygen functional groups from GO, it is possible to selectively remove organic impurities from mixtures. This has applications towards a variety of industries such as food, textile, and pharmaceuticals. This study aimed to prepare heterostructures made up of TiO2 and GO combined in different proportions. The GO was prepared using a modified Hummer’s method in which we took graphite, reacted it with a mixture of H2SO4 and HCl, and then stirred at room temperature for 72 hours. By reacting this mixture with KMnO4, we were able to insert oxygen functional groups in the GO. The TiO2 was prepared by reacting metallic Ti with H2O2 and NH4OH, to produce a soluble peroxo complex. We were then able to precipitate this soluble peroxo complex to get an amorphous Ti precursor. Both the Ti precursor and the GO were then combined in different mass ratios and heated in a hydrothermal reactor at 220 °C for 24 hours. Using these conditions, one variable we were able to study was the effect of pH, which were varied from 8 to 11. The synthesized TiO2/GO heterostructures were characterized using X-Ray Diffraction (XRD), Infrared spectroscopy (IR), and UV-Visible spectroscopy (UV-Vis). The XRD indicated that the TiO2 formed was composed mainly of the anatase phase. The IR indicated the presence of different oxygen containing functional groups in the heterostructure surface. Finally, the UV-Vis allowed us to determine the band gap of the TiO2 in these heterostructures.

Influence of the pH on the preparation of heterostructures based on titanium dioxide and graphene oxide (TiO2/GO) by hydrothermal heating

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ACS Fall 2022

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