Synthesis, characterisation and photocatalytic evaluation of modified titania based binary oxide materials

Abstract

The works embodied in this thesis pertains to development of modified titania based binary oxide photocatalysts suitable for abatement of waste-water under visible light. Different titania based catalysts with varying combinations were prepared, characterised and their photocatalytic efficiency were evaluated for some commonly occurring polluting species in aqueous medium. The photocatalytic activities of different catalysts were finally correlated with their physicochemical properties. The works carried presented in different chapters are summarised below. First chapter presents a brief review of available literature on titania based photocatalyst and its different applications. It begins with the discussion on structure and phase transformation of titania followed by different synthesis strategies applied. Addition of secondary metal oxides such as SiO 2 , ZrO 2 and WO 3 generally increases the photocatalytic efficiency of TiO 2 . Since Si and Zr both has same oxidation state as that of Ti, the recent developments on TiO 2 -SiO 2 and TiO 2 -ZrO 2 binary oxides photocatalysts have been discussed in details. Visible light absorption can be achieved by proper modulation of the band gap of titania through different techniques. In comparison to metal doping, modifications of the anion network by non-metal doping seem to be more promising as far as visible light absorption is concerned. Hence, effects of doping/co-doping of non-metal such as N, F, C, S etc. have been thoroughly reviewed.