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

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.