A Novel Oxidation-Reduction Route for Layer-by-Layer Synthesis of TiO_2 Nanolayers and Investigation of Its Photocatalytical Properties

摘要

Layer-by-layer (LbL) synthesis of titanium dioxide was performed by an oxidation-reduction route using a Ti(OH)_3 colloid and NaNO_2 solutions. Amodel 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]HSO_4~- adsorbed onto the surface of substrate. During the next stage of treatment in NaNO_2 solution, the particles were oxidized to Ti(OH)_4. Photocatalytic activity was studied by following decomposition ofmethylene 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.