All-day freshwater and power generation via integrated photothermally enhanced thermoelectrics and evaporative cooling

Abstract

Solar-powered simultaneous electricity and freshwater production is a promising solution to address energy and water shortages. However, current technologies are limited by their reliance on sunlight and have yet to achieve both efficient electricity generation and effective water collection. Here, we develop an all-day continuous power and freshwater generator (ACPFG) that innovatively integrates thermoelectric and evaporative cooling technologies. During the day, sunlight is absorbed and converted into heat by a low-emissivity absorber, while passive water flow establishes a substantial thermal gradient across the system. At night, evaporative cooling lowers the temperature below ambient, creating an additional thermal gradient across the generator. This enables continuous operation day and night. Our system achieves an unprecedented peak power density of 1.837 W m⁻² and a record-breaking freshwater collection rate of 0.986 kg m⁻² h⁻¹ under 1.0 sun irradiation. At night, it maintains an impressive open-circuit voltage of over 80 mV and a water collection rate of 0.0896 kg m⁻² h⁻¹, demonstrating its all-day production capability. Remarkably, the ACPFG can be readily scaled to power common electrical appliances. This work paves a practical zero-carbon pathway for sustainable water–electricity cogeneration in off-grid remote areas at any time.