Titania modified nanoparticles have been prepared by the photodeposition method employing platinum particles on the commercially available titanium dioxide (Hombikat UV 100). The properties of the prepared photocatalysts were investigated by means of the Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), atomic force microscopy (AFM), and UV-visible diffuse spectrophotometry (UV-Vis). XRD was employed to determine the crystallographic phase and particle size of both bare and platinised titanium dioxide. The results indicated that the particle size was decreased with the increasing of platinum loading. AFM analysis showed that one particle consists of about 9 to 11 crystals. UV-vis absorbance analysis showed that the absorption edge shifted to longer wavelength for 0.5% Pt loading compared with bare titanium dioxide. The photocatalytic activity of pure and Pt-loaded TiO₂was investigated employing the photocatalytic oxidation and dehydrogenation of methanol. The results of the photocatalytic activity indicate that the platinized titanium dioxide samples are always more active than the corresponding bare TiO₂for both methanol oxidation and dehydrogenation processes. The loading with various platinum amounts resulted in a significant improvement of the photocatalytic activity of TiO₂. This beneficial effect was attributed to an increased separation of the photogenerated electron-hole charge carriers.

Modified Pt-TiO₂ NPs/decorated carbon nanotubes were synthesized utilizing sonochemical/hydration—dehydration techniques. Pt was loaded on TiO₂ by a photodeposition method keeping in mind the end goal to achieve electron—hole pair separation and promote the surface reaction. The morphological and basic properties of Pt-TiO₂/fCNTs were investigated by field emission scanning electron microscopy (FESEM), high resolution transmission electron microscopy (HRTEM), powder X-ray diffraction (XRD), UV—vis diffuse reflectance spectroscopy (DRS), photoluminescence (PL) and Raman spectroscopy. The selected area electron diffraction (SAED) patterns of Pt-TiO₂/fCNTs were obtained utilizing TEM-based energy dispersive X-ray spectroscopy (EDXS) analysis. It was found that the TiO₂ nanoparticles were uniformly distributed on the fCNTs, and the Pt particles were decorated on the surface of TiO₂/fCNTs. The photocatalytic hydrogen production activity of the Pt_(0.5%)-TiO₂/fCNTs_(0.5%) nanoparticle composites was investigated using a sacrificial agent methanol solution. Pt-loaded TiO₂ demonstrated a hydrogen evolution rate around 20 times that of TiO₂/fCNTs_(0.5%) (fSWCNTs, fMWCNTs). When compared with platinized TiO₂ in methanol, which was utilized as a control material, Pt-TiO₂/fCNTs demonstrated an almost 2-fold increment in hydrogen generation.

The photocatalytic degradation of EDTA has been investigated in detail under pH-controlled conditions employing the pH-stat technique. The results indicate that by holding the pH constant (i.e., at pH 5) during the experiment, the photocatalytic degradation rate is enhanced by ca. 50% as compared with measurements carried out under “free-floating” pH conditions, i.e., with the pH being adjusted to 5 at the beginning of the reaction. The higher photocatalytic activity at a constant pH of 5 is explained by the higher adsorptivity of EDTA on TiO₂ at this pH as evinced from the dark adsorption measurements. Investigations carried out at different light intensities indicate that the rate of the photocatalytic EDTA degradation is proportional to the square root of the light intensity at moderate values becoming independent from the light intensity at higher values. The activation energies for the photocatalytic EDTA degradation and for its complete mineralization, respectively, have been determined to be 21.54 ± 1.4 kJ mol⁻¹ and 16.4 ± 0.5 kJ mol⁻¹, respectively, employing the Arrhenius data treatment. This difference is explained by the fact that the intermediates formed upon the photocatalytic EDTA degradation are less resistant against their photocatalytic mineralization than the parent molecule.