Energy-Harvesting Evaporator Mimics Photosynthesis-Respiration Cycle and Enables All-Day Seawater Desalination

Solar desalination holds promise for alleviating water scarcity but faces challenges in cold and low-light environments. Inspired by the environmental heat utilization and energy-storage capability of frost-resistant beetles, we designed a sandwich-structured environmental energy utilization evaporator (EUE) incorporating energy-storage microcapsules within a PVA hydrogel and a photothermal PV-Joule heating module. The EUE achieves evaporation rates of 2.12 and 10.05 kg m^-2 h^-1 under photothermal and dual photothermal PV-Joule heating modes, respectively. During darkness, the photosynthesis-like operation utilizes stored PV electricity to maintain stable evaporation. Energy flow modeling indicates a 174% improvement in total energy input for evaporation compared to that of single-solar desalination. Furthermore, machine-learning simulations validate the system's performance across diverse climates, demonstrating consistent operation in cold regions. The EUE achieves excellent all-day water production (∼43.9 kg m^-2), illustrating stable and high-performance evaporation in cold climates. This research provides a viable approach to all-weather desalination and a proof-of-concept for expanding solar-driven evaporation applications.