Fabrication and Characterisation of Titanium Dioxide Based Materials for Photocatalytic Degradation of Methylene Blue Dye

Abstract

Heterogeneous photocatalysis plays a significant role in the environmental science and technology. This subject has gained a great interest in recent years due to many developments, for example, environmental remediation and water splitting, which can be assisted by using photocatalytic materials. This research focuses on the enhancement and the improvement of the performance of existing photocatalysts as well as the development of the new ones. One of these effective photocatalysts are graphene-based photocatalysts, especially, graphene titania-based materials. Graphene is monolayer of carbon atoms, and its structure is a hexagonal lattice. Indeed, the excellent properties of graphene, such as large surface area, make it a promising material that can be used for photocatalysis. It has been shown that a combination of graphene with semiconductors plays a critical role in improving the photocatalytic activity. This type of photocatalysts has the potential to remediate environmental problems. Moreover, covalent functionalisation of graphene with visible active dyes showed a promising approach to modulate graphene by opening its band gap which leading to enhancing properties of graphene. This thesis explores the design of new materials for the application in heterogeneous photocatalysis. The thesis describes (1) the preparation of TiO2 and graphene-TiO2 composites using solvothermal method, (2) the preparation of diazonium salts (DS) of neutral red (NR) dye, (3) the functionalisation of graphene using electron transfer chemistry by one- pot method and finally (4) the incorporation of visible active dyes with graphene-TiO2 nanocomposites by using solvothermal synthesis. All synthesised materials were characterised by different analytical methods such as PXRD, SEM, FT-IR-UV-Vis, TGA, DSC, TEM and XPS. Then, the photocatalytic efficiency of the obtained samples was evaluated by measuring the photodecomposition of methylene blue (MB), a model of organic pollutant, under UV, Vis and UV-Vis irradiation.