Influence of variable oxidation states of certain metals on the adsorption, electrokinetic and photocatalytic properties of M+n-TiO2 nanocatalysts

Abstract

This thesis demonstrates the importance of oxidation states as an important parameter needed to be considered while preparing a photocatalyst. Herein, the oxidation state effects of particularly Mn and Cr metals on the photophysical, electrokinetic, surface, crystallographic properties and adsorption-desorption equilibrium were investigated. The prepared catalysts were further employed for the degradation of differently charged substrates. It was found that apart from crystal structure and morphological factors which are usually given prior consideration, the oxidation state dependent surface charge demands, zeta and streaming potentials appreciably determine the fate of a photocatalytic process. Further, the substrate nature such as cationic/anionic or different functional groups present in its structure also influence the catalyst-substrate associations. Though, a detailed study has been done in this regard, still there are some points which could be followed to extend the research work. There are so many metals such as Os, Sn, W, Re and Fe etc that exhibit a great variation in their oxidation states and are cost effective too. There are also charged substrate molecules which are otherwise non separable using neutral catalysts so, the oxidation states of these metals can be applied in this direction for environmental purposes. We have analyzed the catalytic oxidation properties of the prepared catalysts. However, the study of effect of variable oxidation states can be further continued for energy and other catalytic fields like hydrogen production and photoreduction reactions as well.