Thermo-Optical Characterization of Cu- and Zr-Modified TiO2 Photocatalysts by Beam Deflection Spectrometry

Cu/Zr-modified TiO2 photocatalysts were prepared in the form of nanopowders and characterized by photothermal spectrometry, UV–Vis spectrophotometry and X-ray diffraction (XRD) to investigate the effect of Cu/Zr content on their thermo-optical and transport properties. Adding Cu (0.05%) caused a change in the light absorption range limit, which reduced from 3.25 eV for pure TiO2 to 2.85 eV for Cu-modified TiO2. The decrease in energy band gap was accompanied by a 19.5% decrease in the charge carrier lifetime, which is not favorable for photocatalysis. The decrease in charge carrier lifetime can be minimized by additional modification of TiO2 with Zr (1%), which showed insignificant effects on the energy band gap of the investigated materials. Furthermore, modification of TiO2 with Zr affected the material’s structure and increased its specific surface area, which improved the adsorption of degraded compounds as well as the absorption of light. Altogether, these effects resulted in higher photocatalytic degradation rate constants of the investigated TiO2-based photocatalyst. It was also found that modification of TiO2 with Cu and/or Zr increases both the material’s thermal diffusivity and conductivity due to changes in the band gap and structure of material. Beam deflection spectrometry (BDS) has demonstrated high potential in materials’ characterization which stems from its high sensitivity and precision.