In situ generation of TiO2 nanoparticles using chitosan as a template and their photocatalytic activity

• TiO2 nanoparticles were generated in-situ through a non-hydrolytic sol–gel process on chitosan.
• The presence of chitosan limited the agglomeration of the TiO2 particles.
• The crystallization temperature was shown to be greatly affected by the presence of chitosan film.
• The hybrid chitosan-TiO2 films exhibited photocatalytic activity under visible light illumination.

Hybrid chitosan-TiO2 photocatalysts were prepared by means of in situ generation of TiO2 through a non-hydrolytic sol–gel process, using tetrabutyl titanate, as a precursor, tert-butanol as solvent, and chitosan as a template. TiO2 nanoparticles in the anatase and amorphous forms, with sizes ranging from 5 to 15 nm were generated according to the heating temperature. Evidence of the microstructure evolution of the generated TiO2 nanoparticles were provided by XRD, Raman, XPS and UV–vis diffuse reflectance analysis. The in situ generation of TiO2 NPs and their immobilization on the surface of the chitosan was shown to be effective in controlling the crystallization process and to limit the aggregation of the NPs during the thermal treatment. The chitosan templating and the non-hydrolytic sol–gel approach has contributed to lower the onset crystallization temperature of anatase TiO2 to about 150 °C. The hybrid chitosan-TiO2 nanomaterials showed good photocatalytic activity under visible-light illumination.

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