Photocatalytic Ability of Visible-Light-Responsive TiO₂ Nanoparticles

The synthetic procedures for preparation of free-standing and attached to polymer support surface-modified TiO 2 nanoparticles (NPs) with absorption extended into the visible spectral region due to charge transfer complex formation were developed. The one-step synthesis of colloids consisting of surface-modified TiO 2 NPs is based on the reaction between titanium(IV) isopropoxide (TTIP) and lauryl galatte in nonprotic organic solvents (tetrahydrofuran, xylol, chloroform). The poly(GMA- co -EGDMA) copolymer decorated with surface-modified TiO 2 NPs was obtained in two steps. First, copolymer was functionalized with dopamine and then treated with TTIP in organic solvent at slightly elevated temperature. Thorough microstructural and optical characterization of free-standing and attached to polymer support surface-modified TiO 2 NPs was performed involving transmission electron microscopy as well as absorption and reflection spectroscopy. Infrared spectroscopy was used to understand coordination of ligands to surface Ti atoms. Photoredox chemistry of surface-modified TiO 2 NPs attached to the polymer support was tested. Enhanced photooxidative ability of composite was demonstrated by degradation of organic dye crystal violet under visible light illumination, i.e., using photons with energy smaller than 2.75 eV. On the other hand, photocatalytic hydrogen production was used to demonstrate photoreduction ability of surface-modified TiO 2 NPs attached to the polymer support.