Sol–gel and low-temperature solvothermal synthesis of photoactive nano-titanium dioxide

Photoactive nano-titanium dioxide, as anatase phase, was obtained by the sol–gel method coupled with the solvothermal technique at short crystallization time (2 h) and low temperature (200 °C), using tetraisopropyl orthotitanate as Ti-precursor and 2-propanol as solvent. Precursor ratios were evaluated to determine their influence in the synthesis. Methyl orange was used as model molecule for the photocatalytic degradation. Highest anatase crystallinity was obtained when the water content is close to the stoichiometrically needed to hydrolyze a molecule of TIOT and these materials also showed the highest methyl orange photodegradation.

SEM micrographs of the synthesized TiO2 using the sol–gel method and the solvothermal technique.Figure optionsDownload as PowerPoint slideHighlights
► Nano-titanium dioxide was obtained by the sol–gel and the solvothermal methods.
► When the water is close to the stoichiometrical to TIOT hydrolyze leads to anatase.
► High anatase crystallinity is a crucial feature to photocatalytic activity.