Design and characterization of self-cleaning cotton fabrics exploiting zinc oxide nanoparticle-triggered photocatalytic degradation

Self-cleaning surfaces are functional structures with application in smart textiles. In this study, self-cleaning cotton fabrics were fabricated by coating photocatalytic zinc oxide nanoparticles (ZnO NPs) on cotton surfaces, using a traditional dip-pad-dry-cure coating process. The coatings and ZnO content-dependent self-cleaning properties of the coated fabrics were investigated to evaluate their potential in practical application. The ZnO NP-coated cotton fabrics were characterized by Fourier-transform infrared spectroscopy, X-ray diffraction, field-emission scanning electron microscopy, and thermogravimetric analysis. Methylene blue was used as a test contaminant to qualitatively assess the self-cleaning properties of the fabrics. The removal efficiency was determined for fabrics with different ZnO contents, under different solar irradiation times. Consecutive photocatalytic degradations were carried out to investigate the self-cleaning durability of the fabrics. This involved repeatedly contaminating the same fabric position and subsequent cleaning by photocatalytic degradation. The self-cleaning properties of the fabrics depended on their ZnO NP content. A higher wt% of ZnO NPs in the coated fabric resulted in more pronounced photocatalytic degradation than fabrics with a lower wt%. The self-cleaning performance of the higher wt% ZnO NP fabric decreased slightly after the third consecutive photocatalytic degradation. Results of wash fastness showed color removal after 10 times washing under light irradiation. Moreover, the ZnO NP-coated fabrics exhibited excellent ultraviolet blocking properties. These findings provide a potential model for the practical application of self-cleaning textiles.