Improvement of Orange II Photobleaching by Moderate Ga3+Doping of Titania and Detrimental Effect of Structural Disorder on Ga Overloading

Václav Štengl,Martin Kormunda,Jiří Henych,Michaela Slušná,Tomáš Matys Grygar,Jana Velická

doi:10.1155/2014/468271

Abstract

Highly photoactive Ga3+-doped anatase modification of titania was prepared by homogeneous hydrolysis of aqueous solutions mixture of titanium oxo-sulphate TiOSO4and gallium(III) nitrate with urea. Incorporation of Ga3+into the anatase lattice has a clear positive effect on the photocatalytic activity under UV and Vis light irradiation up to a certain extent of Ga. Ga3+doping decreased the size of the crystallites, increased surface area, and affected texture of the samples. Higher amount of gallium leads to the formation of a nondiffractive phase, probably photocatalytically inactive. The titania sample with 2.18 wt.% Ge3+had the highest activity during the photocatalysed degradation in the UV and visible light regions; the total bleaching of dye Orange II was achieved within 29 minutes. Ga concentration larger than 5% (up to 15%) significantly inhibited the growth of the anatase crystal domains which formed the nondiffractive phase content and led to remarkable worsening of the photobleaching efficiency.

Highlights

Nowadays, attempts by numerous synthesis chemists are focused on the increase of the photocatalytic activity of titanium dioxide so it can be commercially used for various applications, such as self-cleaning coating and air and water purifiers
We present preparation of Ga3+ substitutionally doped titania, nanostructured materials with high photocatalytic activity, obtained by homogeneous hydrolysis of TiOSO4 and Ga(NO3)3 with urea
The crystallite size of anatase decreases from 7.2 nm to 4.4 with growing gallium content, which is related to an increase of the nondiffractive phase

Summary

Introduction

Attempts by numerous synthesis chemists are focused on the increase of the photocatalytic activity of titanium dioxide so it can be commercially used for various applications, such as self-cleaning coating and air and water purifiers. An important factor for the commercial use of TiO2 as photocatalyst is its low cost. The photocatalysts performance can be improved basically in two ways. By ion doping to change the electronic structure or by finding a suitable compromise between morphology, structural parameters, and texture of photocatalyst because, for instance, shape of particles and their size fundamentally affect photocatalytic properties. Optimal particle size for photocatalytic applications lies somewhere around 40–80 nm. Last but not least the crystallinity of particles plays an important role, because the high content of the amorphous domains has detrimental effect on the performance

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