Hierarchically Architected 3D-Printed Hydrogel Evaporators Enable Synergistic Salt Management and Photocatalytic Purification

Abstract Interfacial solar-driven water evaporation offers a sustainable route to clean water production, but faces critical challenges of salt accumulation and organic contamination in complex industrial wastewater treatment. To address these challenges, we engineered a multifunctional 3D-printed hydrogel evaporator with vertically aligned grid architectures and hierarchical porosity. This unique structure promotes rapid water replenishment and Marangoni-driven salt back-diffusion through millimeter-scale channels, effectively preventing salt crystallization. By integrating carbon black and the metal–organic framework PCN-224 into the printing ink, we constructed a dual-functional photothermal–photocatalytic system. This synergistic combination not only enhances light absorption and photothermal conversion but also significantly reduces the water evaporation enthalpy. Coupled with heat-accelerated reaction kinetics, the system achieves efficient broad-spectrum photocatalytic degradation of organic pollutants. The resultant composite evaporator attains a high water evaporation rate of 2.04 kg m⁻ 2 h⁻ 1 under one-sun illumination, maintaining stable performance across a wide salinity range. Simultaneously, it degraded 96.5% of rhodamine B within 60 min under 1.5 kW m⁻ 2 irradiation. This work demonstrates a synergistic strategy for simultaneous solar water production and purification, providing an efficient and environmentally friendly solution for advanced wastewater treatment.