Characterization of Pure and Modified TiO$_{2}$ Layer on Glass and Aluminum Support by Beam Deflection Spectrometry

Abstract

$\mathrm {TiO}_{2}$ thin films used as photocatalysts in environmental applications were studied by beam deflection spectroscopy (BDS) and by atomic force microscopy. A novel multiparameter theoretical model was developed in order to explain BDS experimental data. The fundamental parameters of examined films: thermal diffusivity, thermal conductivity, and charge transport properties such as the value of the energy bandgap, carrier lifetime, concentration, and type of dopants, were obtained as results of the modeling of BDS data. With BDS, we observed that the material’s thermal conductivity and thermal diffusivity depend also on the porosity and the surface roughness of films. Consequently, the photocatalytic performance can be estimated by measuring the thermal diffusivity of films. Furthermore, we found that surface roughness is prone to changes when the film is used as photocatalysts in water purification processes. During the purification process, the roughness decreases and the photocatalytical performance drops. Moreover, it was discovered that the thermal, electrical, and morphological properties of photocatalysts films depend on the support to which the $\mathrm {TiO}_{2}$ layer is deposited. These complex relations demonstrate that knowledge of fundamental physical parameters is required in order to improve the photocatalytic performance of $\mathrm {TiO}_{2}$ films. In this view, the BDS measurements offer a tool for noncontact and nondestructive evaluation of thermal and electronic parameters of thin film $\mathrm {TiO}_{2}$ photocatalysts as demonstrated in this work.