Preparation and Characterization of TiO_2 Nanostructures for Catalytic CO_2 Photoconversion

摘要

The titanium dioxide target (99.7%) of 1 cm in dia was ablated in vacuum by laser pulses (6 ns) at 266 nm and at repetition rate of 10 Hz. During deposition the laser fluence between 1 and 3.5 J/cm~2 and the O_2 pressure from the range of 10~(-2) - 1 Pa were applied. The thin TiO_2 films were deposited on glass substrate (1×1 cm~2) heated up to 500°C. The chemical composition of the film and samples produced by annealing were investigated by spectroscopic techniques (μ-Raman, EDX) and the structure, porosity and surface morphology were analysed by means of SEM and xray diffraction (XRD). The SEM inspection of the TiO_2 thin film samples indicates that the obtained material is mostly crystalline. After annealing in O_2 at 500°C the structure characterized by the presence of both anatase and rutile phases is observed in the Raman spectra and confirmed by the XRD data. The phase content ratio depends on the O_2 pressure applied. Results confirm that nanostructures produced in this way represent densely packed columns and promote deep penetration of guest particles such as CO_2. The resulting large active surface is advantageous from the point of view of photocatalytic applications.