Interfacial Solar Vapor Generation: Materials and Structural Design

ConspectusThe global water scarcity and deteriorating environment call for the development of environmentally friendly water treatment technologies. Solar-driven evaporation, well-known as a critical step of water cycles, provides a natural inspiration for water treatment and purification with a minimized carbon footprint. The emergence of interfacial solar vapor generation enabled through carefully tailored materials design in recent years offers an effective approach to enhance solar evaporation, with unique thermodynamic and kinetic advantages. Thermodynamically, by localizing absorbed solar energy at the water surface to avoid thermal dissipation into the entire body of water, high solar vapor transfer efficiency can be achieved. Kinetically, because of reduced thermal mass, a short response time of vapor generation and fast ramping of vapor temperature can be expected.In this perspective review, we start by exhibiting the structural designs of interfacial solar vapor generators to improve the energy transfer efficiency and evaporation rate: first, tuning optical structures to improve the light absorption; second, designing a two-dimensional water path and bioinspired structures to reduce the heat loss; third, harvesting environmental energy as an extra energy input to further increase the evaporation rate. Then, we demonstrate the intrinsic thermodynamic and kinetic advantages of interfacial solar evaporation for various applications. On the thermodynamic side, low energy loss and a high evaporation rate enable effective desalination and water treatment. While on the kinetic side, quick-response and high-temperature steam generation has direct implications in fields like sterilization and power generation. In the end, we briefly conclude the main challenges in fundamental and technical aspects as well as discuss various promising pathways for future development.