Enhancing the Photocatalytic Activity of Immobilized TiO 2 Using Laser-Micropatterned Surfaces.

In the past, the application of TiO₂ slurry reactors has faced difficulties concerning the recovery and reusability of the catalyst. In response to these challenges, immobilized photocatalyst systems have been investigated, wherein the catalyst is fixed onto a solid support, frequently with reduced photocatalytic performance. In the present study, thin TiO₂ films were developed in the anatase phase by the sol-gel process and spin-cast on laser-microstructured silicon substrates, to form photocatalytic surfaces of increased activity. The TiO₂ films were thoroughly characterized using SEM-EDX, XRD, UV–Vis spectroscopy, and Raman spectroscopy. The photocatalytic activity of these surfaces was evaluated by the degradation of atrazine in aqueous solution under UV irradiation. Their photocatalytic activity was found to be significantly enhanced (mean k_obs 24.1 × 10⁻³ min⁻¹) when they are deposited on laser-microstructured silicon compared with flat silicon (mean k_obs 4.9 × 10⁻³ min⁻¹), approaching the photocatalytic activity of sol-gel TiO₂ fortified with Degussa P25, used as a reference material (mean k_obs 32.7 × 10⁻³ min⁻¹). During the photocatalytic process, several transformation products (TPs) of atrazine, namely 2-chloro-4-(isopropylamino)-6-amino-s-triazine (CIAT), 2-chloro-4-amino-6-(ethylamino)-s-triazine (CAET), and 2-chloro-4.6-diamino-s-triazine (CAAT), were identified with LC–MS/MS. The stability of the photocatalytic surfaces was also investigated and remained unchanged through multiple cycles of usage. The surfaces were further tested with two other pollutants, i.e., 2,4,6-trichlorophenol and bisphenol-a, showing similar photocatalytic activity as with atrazine. [ABSTRACT FROM AUTHOR]