Advanced Chitin Nanocrystals/CeO₂ Derived Hydrogel for Efficient Solar Steam Generation and Antibacterial Performance

Hydrogel-based solar evaporators have garnered attention in solar-powered interfacial evaporation for clean water due to their hydrophilicity, porous structure, and large surface area. However, achieving high evaporation rates, robust mechanical properties, and antibacterial performance remains challenging. In this study, we successfully construct a composite hydrogel solar evaporator with excellent comprehensive performance. Cerium dioxide (CeO₂) nanoparticles with antibacterial properties are synthesized in situ using chitin nanocrystals (ChNC) as bio-based reinforcing nanofillers. These components are integrated with polypyrrole (PPy) as a photothermal absorber and poly(vinyl alcohol) (PVA) as the structural backbone. The nanocomposite hydrogel evaporator is prepared via a freeze-thaw cycling method. The 15%-ChNC/CeO₂/PPy/PVA (15%-CCPP) nanocomposite hydrogel exhibits superior compressive strength, achieving 62.4 kPa at a 60% compression rate, 2.25 times higher than pure PVA hydrogel. In addition, the 15%-CCPP hydrogel demonstrates significant antibacterial activity. Meanwhile, the nanocomposite hydrogel achieves a high evaporation rate of up to 2.65 kg·‍m^-2·h^-1 under 1 Sun (1.0 kW·m^-2) irradiation. The combination of excellent mechanical properties, antibacterial performance, and high evaporation efficiency highlights the potential of this nanocomposite hydrogel evaporator for application in the solar-powered water purification systems.