Photocatalytic Reduction of Nitroaromatics Initiated by Bare Metal TiO2 Nanostructures

Abstract

This thesis presents a fine approach into many aspects of Titanium dioxide (TiO2) nanomaterials and their applications for photocatalytic reduction of nitroaromatics. Bare and metal loaded TiO2 nanostructures viz., nanospheres and nanorods of different crystal phases viz., anatase and rutile have been synthesized to investigate the effect of size, shape, phase, nature of co-catalyst onto the change in absorbance, photoluminescence, relaxation lifetime and photocatalytic activity for the reduction of nitroaromatics. The present thesis is divided into five chapters: Chapter 1: Introduction, Preparation and Characterization Techniques The first chapter introduces the brief mechanism of TiO2 semiconductor photocatalysis, effect of metal loading onto TiO2, crystal phase, morphology, photoreduction of nitroaromatics with TiO2 and literature survey on TiO2 nanostructures with photocatalysis as an application point of view. Further, various techniques used for synthesis and characterization of bare and metal loaded TiO2 nanocomposites are discussed. TiO2 nanostructures of different morphologies viz.; nanospheres and nanorods as well different phase viz.; anatase and rutile have been synthesized by calcinations at temperature 400-800 ºC, hydrothermal, solvothermal and sol gel methods. Coinage and platinum group metals were deposited onto TiO2 surface by photodeposition techniques. The as synthesized materials have been characterized by diffused reflectance spectroscopy, photoluminescence; time resolved spectroscopy, transmission electron microscope, BET surface area analyzer and X-ray diffraction study. Photoreduction of nitroaromatics were conducted under UV light irradiations. Products and intermediates have been identified by high performance liquid chromatography, gas chromatography-mass spectroscopy, nuclear magnetic resonance spectroscopy and gas chromatography techniques.