Noble metal-modified TiO₂ obtained by the sol--gel method: Ethanol photodegradation

Introduction: Nanopowders with different compositions, purities, sizes, and dimensional distributions can be created using the sol--gel method [1,2]. The metal precursors were added either during synthesis (in a single step) or by post-synthesis impregnation to the sol--gel method used for obtaining the powder photocatalysts.

Methods: The materials used include ethanol, TiO₂, and Pt/TiO₂ powders (obtained by the sol--gel method). Characterization methods such as thermal analysis (DTA), infrared spectroscopy (IR), X-ray diffraction (XRD), and X-ray fluorescence (XRF), and the determination of the specific BET surface area and pore distribution, are complementary and necessary.

Results: As a result of the post-synthesis heat treatment, oxide compounds were obtained in the form of white (TiO₂) and gray (Pt-modified TiO₂) crystallized powder. The photocatalytic activity of titanium dioxide synthesized by the sol--gel route was compared to that of pristine and platinum doped photocatalysts, both during synthesis and by post-synthesis impregnation. As a result of the post-synthesis heat treatment, oxide compounds were obtained in the form of white (TiO₂) and gray (Pt-modified TiO₂) crystallized powder. The photocatalytic activity of titanium dioxide synthesized by the sol-gel route was compared to that of pristine and platinum-doped photocatalysts, both during synthesis and by post-synthesis impregnation. The samples were tested as photocatalysts in the oxidative degradation of ethanol in the gaseous phase and under solar simulated light irradiation. The folliwing is an increasing order of powder reactivity in the photocatalytic tests: TiO₂, TiO₂-Pt in-situ, and TiO₂-Pt by post-synthesis impregnation (with the highest conversion being 72,24%).

Conclusions: The topic of this paper focuses on the development of the photocatalytic activity of simple and noble metal-modified TiO₂ used for the degradation of contaminants in the gas phase and ambient conditions.

References:

• Sakka, Sol-gel process and applications, Handbook of Advances Ceramics, Elsevier, 883–910 (2013).
• Savolainen et all, Nanotechnologies, engineered nanomaterials and occupational health and safety, Safety Science, 48 (8), 957–963 (2010).