Hybrid cotton–anatase prepared under mild conditions with high photocatalytic activity under sunlight

Abstract

Cotton fibres were coated with nanolayers of TiO₂, anatase, using a new approach based on a non-hydrolytic sol–gel process followed by a mild hydrothermal treatment at a temperature lower than 140 °C. The crystallization process was followed by Raman spectroscopy and XRD, and the change in the chemical environment of Ti resulting from the hydrothermal temperature was analyzed using XPS. Changes in the morphology of the ensuing NPs on the different cotton samples were studied by FE-SEM. UV-Vis absorption spectra and the luminescence properties of the TiO₂, as well as their thermal properties, were also investigated. To explain the TiO₂ crystallization at temperatures much lower than 350 °C, a growth mechanism of TiO₂ nanocrystallites (diameter < 15 nm) was proposed to proceed via coordination and ligand exchange of Ti(OBu)₄ with the cotton surface hydroxyl groups followed by edge-sharing polycondensation during the hydrothermal process. Also the presence of acetic acid was revealed crucial in the mechanism. The hybrid cotton–TiO₂ was shown to exhibit a good photocatalytic activity for the degradation of an organic dye – Remazol Brilliant Blue R. The preparation technique is reliable, easy to implement and can be also applied to cotton fabrics to create self-cleaning and protection textiles under visible irradiation. Reusability of the cotton samples was investigated.