Bio-Doped Photoactive Hybrid Hydrogel for Synergistic Clean Water Production and Decontamination

Concurrent clean water generation and contaminant degradation from organic wastewater remain a significant challenge. In this work, we developed a natural down fiber-doped titanium dioxide (DF-TiO₂)/down fiber carbon (DFC) hybrid hydrogel that integrates efficient solar-driven water evaporation with visible-light photocatalytic decontamination. Unlike conventional chemical doping, the incorporation of biomass-derived DF introduces C, N, and S elements into the TiO₂ lattice, narrowing the bandgap and suppressing electron-hole recombination, as confirmed by density functional theory calculations. By coupling DF-TiO₂ with DFC in a chitosan-poly(vinyl alcohol) hydrogel matrix, the resulting DF-TiO₂/DFC hybrid hydrogel possessed satisfactory mechanical properties, high light absorption capacity, sufficient water supply, and visible-light-driven catalytic activity. As a result, the DF-TiO₂/DFC hydrogel demonstrated an evaporation rate of 2.14 kg·m^-2·h^-1 and a concurrent methyl orange (MO) degradation efficiency of 93.1% after 5 h under 1 sun illumination. Furthermore, the hydrogel retained its evaporation performance after continuous 5 h of evaporation for various contaminants, including MO, rhodamine B, and tetracycline. Actual outdoor experiments demonstrated an evaporation rate of 2.25 kg·m^-2·h^-1 at 2:00 p.m. and a simultaneous MO degradation efficiency of 93.79% from 8:00 a.m. to 6:00 p.m. This approach provides new perspectives on the sustainable bio-doping of catalytic materials and their use in high-tech applications, such as advanced solar evaporation, photocatalytic hydrogen production, photocatalytic carbon dioxide reduction, and other related areas.