Silver sulfide quantum dots as sensitizer in self-cleaning of Bombyx mori silk fabrics with nano-titania

In this paper, silver sulfide (Ag2S) quantum dots (QDs) were prepared and used as sensitizers in self-cleaning of Bombyx mori silk fabrics which were firstly treated with anatase nanotitania (TiO2) sols prepared under room temperature, then with Ag2S QDs modified by 2-Thioglycolic acid (TGA) or (3-Mercaptopropyl) trimethoxysilane (MPS). X-ray diffraction analysis reveals much purer and smaller sizes of acanthite phase of Ag2S QDs modified by MPS than those by TGA. Lower concentrations of silver ions in samples of MPS-Ag2S-modified fabrics were demonstrated by X-ray photoelectron spectra analysis. Degradation of methylene blue by Ag2S QD-sensitized TiO2 is in accordance with pseudo-first kinetic model. Decrease in contact angles and decoloration of red wine on silk fabrics show that Ag2S QDs modified by TGA or MPS can be used as sensitizer in photocatalytic reactions of TiO2. TGA appears highly efficient than MPS in sensitizing TiO2 with Ag2S QDs.