Synergistic Solar Interfacial Evaporation and Photocatalysis Enabled by a Hierarchical Porous Hydrogel Reactor

The concurrent generation of clear water and degradation of pollutants using sunlight represents a sustainable solution to global water scarcity. However, integrating photothermal evaporation and photocatalysis within a single device remains challenging due to competing requirements for light and mass management Inspired by natural transpiration, we engineer a bilayer porous hydrogel interfacial reactor that synergistically couples these processes through designed heat, mass, and charge transport. The reactor features an upper hydrogel layer embedding polydopamine modified TiO 2 and carbon black nanoparticles for broadband light harvesting and charge transfer, and a lower 3D‐printed insulating supporter for continuous capillary water supply and heat localization. Evaporation‐driven convection enriches pollutants at the catalytic interface, while photothermal heating enhances reaction kinetics, establishing a self‐reinforcing photothermal‐photocatalytic loop. Under 1 sun irradiation, the reactor achieves an evaporation rate of 2.14 kg·m −2 ·h −1 with an efficiency of 95.43%, while enabling continuous in situ photocatalytic degradation of organic contaminants. This work provides a versatile design principle for advanced multifunctional reactors, unifying solar energy conversion with efficient water remediation.