Quinoxaline-6,7-dicarboxylate-based Photothermal Polymers Inspired Multifunctional Hydrogels for High-Efficient Solar-Driven Water Purification.

Solar-driven water purification presents an environmentally sustainable approach to tackle the critical issue of freshwater scarcity. However, developing advanced hydrogel systems that simultaneously achieve efficient solar-thermal conversion and comprehensive pollutant removal remains challenging. This work reports the synthesis of three novel conjugated polymers through molecular engineering of diketopyrrolopyrrole with modified benzo[1,2-c:4,5-c']bis[1,2,5]thiadiazole derivatives to enhance electron-withdrawing characteristics. The optimized molecular structures exhibit extended light absorption and minimized radiative decay through synergistic intramolecular charge transfer and controlled molecular motion in the aggregated state. Among them, PDPP-SeQ achieves a remarkable photothermal conversion efficiency of 26.71% under standard solar illumination. By incorporating PDPP-SeQ micelles into a polyethylenimine/polyvinyl alcohol matrix, we fabricated a multifunctional solar-absorbing hydrogel (SAG-Se). The composite demonstrates exceptional performance, including a record water production rate of 10.18 kg/m2·h with excellent cycling stability, representing the highest reported value among organic photothermal systems. Notably, the design enables concurrent freshwater and electricity generation (55 mV output) without sacrificing evaporation efficiency. The resulting SAG-Se purification platform combines portability with robust treatment capabilities, effectively eliminating contaminants. This study provides fundamental insights into molecular design principles for high-efficiency photothermal materials while demonstrating their practical application in integrated water-energy systems for remote regions.