Plasmonic Metal-TiO2 Nanocatalysts for Water Splitting Under Visible Light Irradiation

Abstract

This thesis elaborates the basis of semiconductor based water splitting reaction with a specific discussion on titanium dioxide (TiO2). The properties, limitations and the measures to improve the photocatalytic activity of TiO2 and the methodology used in the fulfillment of the proposed objectives have been explored. Chapter 2 describes the microwave assisted synthesis of TiO2 nanoparticles followed by its fabrication into a graphene oxide coated and Au deposited core-shell nanocomposite (Au-TiO2@GO). The Au-TiO2@GO nanocomposite has been used successfully for the hydrogen production from water under different light irradiation sources. Chapter 3 discloses that the morphology and surface plasmon resonance (SPR) effect of Ag-TiO2 as the decisive factors for the enhancement of H2 production from water. The rice gain shaped TiO2 nanorods were synthesized by the hydrothermal method. The plasmonic frequency was found to be effective for the interfacial electron transfer from Ag to ECB of TiO2, thereby altering several physicochemical and interfacial properties like fluorescence, current density and enhanced the rate of reaction. Chapter 4 describes the synthesis and application of an Au-TiO2 heterocomposite embedded in a thin layer of graphitic C3N4 has been elaborated. In summary, the C3N4 surface passivated Au-TiO2 tubular nanostructure was found active in direct solar light for the efficient H2 production from half water splitting reaction. Chapter 5 elaborates the fabrication of a Cu2O/Cu based ternary TiO2 hybrid. The role of a photostable mesoporous Cu-mpTiO2 nanocomposite for the efficient hydrogen evolution from the water. It is revealed that the efficiency of Cu-mpTiO2 can be enhanced on the basis of the presence of a balanced amount of co-catalysts (Cu and Cu2O). The Cu2O is capable of harvesting sunlight while as Cu helps for the transport of excited electrons towards ECB of TiO2. Moreover, specific surface area, pore distribution, and oxidation state are found to have a profound effect on overall photocatalytic activity. Chapter 6 presents the synthesis of (001) faceted TiO2 nanosheets and it co deposited composite with Au and Pt. These as prepared Au/Pt-TiO2 nanosheets were utilized as a brilliant photocatalyst for the photocatalytic and photoelectrochemical H2 production from water. The optimized Au0.4/Pt0.75-TNST exhibited good optoelectronic and surface properties; moreover it also showed a brilliant PEC performance.