A Novel Oxidation-Reduction Route for Layer-by-Layer Synthesis of TiO2 Nanolayers and Investigation of Its Photocatalytical Properties

Layer-by-layer (LbL) synthesis of titanium dioxide was performed by an oxidation-reduction route using a Ti(OH)3 colloid and NaNO2 solutions. A model of chemical reactions was proposed based on the results of an investigation of synthesized nanolayers by scanning electron microscopy, electron microprobe analysis and X-ray photoelectron spectroscopy, and studying colloidal solution of Ti(OH)3 with laser Doppler microelectrophoresis. At each cycle, negatively charged colloidal particles of [Ti(OH)3]HSO4- adsorbed onto the surface of substrate. During the next stage of treatment in NaNO2 solution, the particles were oxidized to Ti(OH)4. Photocatalytic activity was studied by following decomposition of methylene blue (MB) under UV irradiation. Sensitivity of the measurements was increased using a diffuse transmittance (DT) method. The investigation revealed strong photocatalytical properties of the synthesized layers, caused by their high area per unit volume and uniform globular structure