Dual-functional hydrogel evaporator with CQDs loaded TiO2 and CNTs for efficient eutrophic water body purification

Solar photothermal interfaces garner widespread attention as an economical and efficient water purification technology, particularly in applications such as seawater desalination and wastewater treatment. However, their relatively limited capacity to degrade organic pollutants in real wastewater, especially in addressing eutrophic water bodies commonly encountered in daily life, hinders their broader practical deployment. Herein, we synthesize a novel bifunctional hydrogel material, PSTCC (PAM/SA/TiO 2 -CQDs/CNTs), which integrates both photothermal and photocatalytic functionalities. We also design and fabricate a 3D structured hydrogel device to systematically evaluate its potential for eutrophic water purification. By incorporating carbon quantum dot - modified TiO 2 and carbon nanotubes into a polyacrylamide–sodium alginate composite matrix, the hydrogel exhibits significantly enhanced photothermal conversion efficiency while effectively tuning the bandgap of TiO 2 , thereby improving its photocatalytic activity. Furthermore, using a 3D structured mold and demolding process, we construct a PSTCC hydrogel evaporator featuring surface convex protrusions and vertically aligned internal capillary channels, which achieves a high evaporation rate of 2.56 kg m −2  h −1 under one sun irradiation. The device also demonstrates excellent performance in the removal of organic pollutants, achieving a photocatalytic degradation efficiency of 85.5 % for methylene blue and an inactivation rate of 58.7 % for Chlorella vulgaris . This evaporator and its associated device are expected to offer a novel paradigm for treating typical organic pollutants in eutrophic water bodies, holding broad application prospects in the field of green, efficient, and energy-saving water treatment.