Abstract
Mesoporous TiO2 powder with large surface area and high porosity was prepared via template-free method of heat-stimulated oxidizing destruction of TiC by HNO3. Anatase crystalline phase of as-prepared and annealed at 200−400°C titania was confirmed by XRD technique. Surface nitrate-nitro groups responsible for high adsorption capacity of the TiO2 powders were studied by FTIR spectroscopy. The annealing temperature can be used as a factor for regulation of titania morphology and structural properties. The rise in the annealing temperature higher than the temperature of nitrate-nitro groups decomposition induces the growth of TiO2 crystallites, decreasing porosity and surface area, the drop of adsorption capacity, and improving photocatalytic activity under UV irradiation.
Highlights
Among various oxide semiconductors, titania is considered as the most important photocatalyst due to its biological and chemical inertness, strong oxidizing power, nontoxicity, and long-term stability against photo- and chemical corrosion [1−4]
Broadened peaks characteristic of anatase TiO2 phase can be seen in the diffractograms, indicating that titanium carbide is completely oxidized by nitric acid resulting in the formation of fine-grained titanium dioxide [24]
Mesoporous TiO2 powders with large surface area and high porosity were synthesized from TiC by oxidation with HNO3 at enhanced temperature
Summary
Titania is considered as the most important photocatalyst due to its biological and chemical inertness, strong oxidizing power, nontoxicity, and long-term stability against photo- and chemical corrosion [1−4]. Ordered mesoporous TiO2 films and powders attracted considerable interest as potential photocatalysts owing to their large surface area and narrow pore size distribution, while retaining a crystalline framework [1−10]. Mesoporous TiO2 was synthesized using alkyl phosphate as a structure-directing template and titanium isopropoxide bis-acetylacetonate as a Ti-containing precursor [13]. The development of ordered large-pore-size mesoporous TiO2 material has been mostly related with the use of surfactants or block polymers as templates. The template removal by calcination generates high-surface-area mesoporous TiO2. The synthesis of mesoporous TiO2 through template-free methods is an important issue from industrial and environmental points of view. Most of the template-free routes for the synthesis of mesoporous TiO2 materials are related with the hydrolysis or oxidation reactions using nitric acid and phosphoric acid as a catalytic or oxidizing agent [21−23]. Attention was given to the characterization of structure, surface properties and photocatalytic activity of the obtained material
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