Phytic Acid-Reinforced Dual-Network Hydrogels with Low Vaporization Enthalpy and Enhanced Antibacterial Activity for Efficient Solar-Driven Water Evaporation

Hydrogels have emerged as one of the most promising platforms for next-generation solar-driven water evaporation (SDIWE), offering a sustainable route to freshwater production due to their tunable physicochemical properties. However, the rational design of hydrogel evaporators that simultaneously reduce vaporization enthalpy, regulate water content, and resist biofouling during long-term operation remains a significant challenge. Herein, we report a phytic acid (PA)-reinforced poly(vinyl alcohol) (PVA)/Chitosan-based hydrogel (PCH) engineered for high-performance solar-driven water evaporation. PA promotes the construction of a dual-network architecture within the PVA-Chitosan matrix, leading to markedly improved mechanical strength and finely tuned hydration behavior. Additionally, the strongly polar character of PVA, chitosan, and PA collectively contributes to a significant reduction in the vaporization enthalpy. These synergistic advantages result in an evaporation rate of 2.60 kg m^-2 h^-1 under 1 Sun illumination, accompanied by excellent salt rejection and effective purification of diverse wastewater streams. Finally, the hydrogel exhibits potent antibacterial activity mediated through chelation, electrostatic interactions, and localized acidification imparted by chitosan and PA. This study underscores the efficacy of rational double-network design using phytic acid as a multifunctional modifier for achieving low vaporization enthalpy, controlled hydration, and enhanced antimicrobial performance, which provide a versatile and efficient strategy toward combating global freshwater scarcity.