Surface modification of TiO2 nanostructures for visible light photocatalyst

Abstract

In this project, we studied the methods to improve the photocatalytic efficiency of

TiO2 nanostructures in pollutant degradation and elimination. From researches done

over years, it is proven that TiO2 is one of the most prominent oxides for photo

catalyst. However, not many studies have been conducted on nanotubes with branched

microstructures. Although nano-sized TiO2 is environmental friendly and cost

effective in terms of photo catalyst performances, its efficiency is low. The main

barrier lies within the issues of quick recombination of electrons, holes pairs and poor

absorbance of visible light. It was shown that TiO2 exhibits photo catalytic behaviour

under UV light, but UV light merely takes up about 4% of the sunlight, but visible

light takes up around half. Hence, extension of the absorption spectrum for TiO2 after

surface modification is one key parameters of our interest. In this project, TiO2

nanorod arrays have been grown on the glass substrates by hydrothermal growth and

were converted into TiO2 nanotube arrays by hydrothermal etching to increase the

surface area further. Ag3PO4 were deposited on the surface of the TiO2 nanorods and

nanotubes and the photocatalytic properties have been enhanced by the Ag3PO4

surface modification. Ag dopants act as electron sinks and can increase electron/hole

lifetime. Moreover, sinks would be aiding electron-hole separation