Chitosan-Promoted TiO₂-Loaded Double-Network Hydrogels for Dye Removal and Wearable Sensors

The loading of photocatalysts on hydrogels can significantly reduce the loss of catalysts and effectively prevent secondary contamination, thus demonstrating great application potential and advantages in the field of wastewater treatment, especially in the removal of dyes. Herein, the semiconductor TiO₂ was successfully loaded into a polyacrylic acid/chitosan (PAA/CS) double-network (DN) hydrogel, which exhibited superior removal of dyes in wastewater such as MG, MB, MV, and RhB. The dye degradation process followed first-order kinetics, and the first-order rate constants for dye degradation were further calculated under UV light irradiation. Furthermore, the photocatalytic mechanism of the hydrogel was explored and analyzed. More interestingly, the PAA/CS-TiO₂ DN hydrogel has excellent tensile properties and superior electrical conductivity, which can be assembled into flexible sensors for real-time monitoring of mechanical deformations and human joint motions. It is envisioned that these excellent properties make hydrogel photocatalysts promising for a wide range of applications.