Preparation and Properties of Cotton Fabric Photocatalyzed by Ag-Doped Madder-Sensitized TiO₂

In this study silver nanoparticles (NP) were grown in-situ on the surface of madder-sensitized TiO2 by an in-situ reduction method using silver nitrate as a silver source and a honeysuckle extract as a reducing agent. Silver doped madder-sensitized TiO2 nanoparticles were then prepared, supported on the surface of cotton fabrics to prepare photocatalytic cotton fabrics with high-efficiency self-cleaning properties and excellent antibacterial properties. transmission electron microscopy (TEM), scanning electron microscopy (SEM), X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS) analyses showed that elemental Ag NPs were deposited on the surface of the madder-sensitized TiO2, and that Ag-doped madder-sensitized TiO2 NPs were successfully loaded on the cotton fabric surface. The results of UV-Visible diffuse reflectance spectroscopy (UV-Vis-DRS) and Photoluminescence Spectroscopy (PL) showed that Ag-doping could further reduce the band gap of madder-sensitized TiO2 than pure TiO2. The absorption of light in the photocatalytic system was increased, and the recombination of electron-hole pairs was effectively inhibited. Compared with madder-sensitized TiO2 photocatalyzed cotton fabric, the degradation rate of nano-Ag-doped madder-sensitized TiO2 photocatalytic cotton fabric for methylene blue (MB) was increased by 10.66% within 2 h, and the degradation process was in line with the first-order reaction kinetic model. After 5 times of washing, the photocatalytic cotton fabric still had excellent photocatalytic performance. Its antibacterial rates against Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus) reached 100 and 99.99%, respectively. In addition, it had good wrinkle resistance and UV protection properties, but the cross-linking modification reduced the breaking strength by about 14%.