To alleviate the scarcity of clean water, solar steam generation, which utilizes the green and abundant resources of Earth, has attracted considerable attention and been recognized as a sustainable technology to purify seawater and wastewater. Within the past five to seven years, building on remarkable advances in the synthesis of nanoscale photothermal materials, significant progress has been made in the design and fabrication of solar evaporators. Here, we comprehensively review the materials and structures of the three key components of solar evaporators: solar absorbers, substrates (i.e., support layers), and water collectors towards efficient harvesting of sunlight, thermal management, water transportation, interfacial evaporation, and collection. In particular, we discuss the design principles of water collectors for solar-driven evaporation, which are in the early stages of development at present. Furthermore, bio-inspired water collectors provide exciting opportunities for the design and realization of efficient water harvesting from solar steam. Finally, we introduce photothermal-enhanced membrane distillation (PMD), a promising alternative technique involving solar-driven interfacial evaporation for producing clean water. PMD combines solar energy and membrane distillation, which facilitates efficient water purification and collection. In this review, we discuss the design guidelines and recent development of this photothermal-enhanced water purification. This review provides useful insights into the material choice and structure optimization to realize enhanced solar evaporators towards freshwater generation.

Solar-driven membrane distillation using photothermal membranes is of considerable interest for future water desalination systems. However, the low energy efficiency, complex synthesis, and instability of current photothermal materials hinder their further development and practicability. In this study, for the first time, we demonstrate a simple, stable, and scalable polydopamine (PDA)-coated polyvinylidene fluoride (PVDF) membrane for highly efficient solar-driven membrane distillation (MD). Our membrane shows the best energy efficiency among existing photothermal MD membranes (45%) and the highest water flux (0.49 kg m⁻² h⁻¹) using a direct contact membrane distillation (DCMD) system under 0.75 kW m⁻² solar irradiation. Such a performance was facilitated by the PDA coating, whose broad light absorption and outstanding photothermal conversion properties enable higher transmembrane temperature and increased driving force for vapor transport. In addition, the excellent hydrophobicity achieved by fluoro-silanization gives the membrane great wetting resistance and high salt rejection. More importantly, the robustness of our membrane, stemming from the excellent underwater adhesion of the PDA, makes the composite membrane an outstanding candidate for real-world applications.