Phase change material enhanced sustained and energy-efficient solar-thermal water desalination

Extracting clean water from seawater based on interfacial evaporation is one of the key energy-effective technologies to alleviate global water scarcity. However, the real-world solar-driven evaporation technology is limited by its poor energy management when facing intermittent solar irradiation, making it heavily dependent on the weather conditions and leading to deteriorated overall energy efficiency. To address the issue, we demonstrate a new conceptual system of solar-driven phase change material-integrated interfacial evaporation. The system enables the whole cycle of light-to-thermal conversion and waste heat storage when irradiated under the unfocused light to latent heat release while the light flux is temporarily faded or blocked. The sustained and high energy-efficiency desalination is achieved in spite of the variable solar flux, in which the total energy loss is only 5.2% of the incident solar energy. The evaporation rate of 0.70 kg m-2h−1 and an energy efficiency of 46.5% under dark conditions are achieved, which is 2.5 times higher compared to the conventional interfacial evaporation. The system exhibits excellent long-term stability in successive heating-cooling cycles without energy efficiency degradation. This work presents a highly promising route for durable and energy-effective evaporation and desalination utilizing intermittent renewable solar energy.