A Yolk@Shell Photothermal Structure for Integrated Solar‐Driven Undrinkable Water Purification and Thermoelectric Power Generation

ABSTRACT Integrated solar‐driven vapor generation and thermoelectric power generation have been considered a promising solution to alleviate the global freshwater shortage and energy crisis. However, the long‐standing trade‐off between high‐speed water evaporation and efficient thermoelectric generation remains a challenge. In this study, a yolk@shell structured photothermal evaporator (denoted as HSS@MNPs) composed of super‐elastic hydrophobic silicone sponge, super‐hydrophilic epoxy resin and photothermal melanin nanoparticles was prepared via simple sol‐gel and spray coating methods. The results show that various waste liquids can be effectively purified, and a series of experiments and analyses demonstrate that the height of the HSS@MNPs and the position of the thermoelectric (TE) module within the photothermal structure affect its water evaporation and thermoelectric performance. By taking advantage of the unique yolk@shell structure of HSS@MNPs, the position of the TE module can be optimized without destroying the self‐floating property, thermal insulation, photothermal property, and water transmission performance of the evaporator. This results in efficient and stable evaporation (3.08–3.17 kg m −2 h −1 )‐thermoelectric (135.4–144.6 mV) co‐generation under one sun irradiation. The outdoor application was also demonstrated, providing a straightforward strategy to resolve the long‐standing trade‐off between high‐speed water evaporation and efficient thermoelectric generation.