Energy–Mass Transfer in Photothermal Desalination: Multi‐Scale Innovations and Distributed Water Solutions toward Sustainability

In response to the dual challenges posed by global water scarcity and carbon neutrality targets, conventional desalination technologies struggle to satisfy the requirements of high energy consumption and inherent limitations associated with centralized water supply systems. Within this context, interfacial solar steam evaporation (ISSE) technology has emerged as a promising solution to mitigate the uneven spatial and temporal distribution of water resources, owing to its advantages of highly efficient photothermal conversion, zero carbon emissions, and modular design. Although ISSE has been developed for tens of years, there are still many challenges to be faced, from fundamental research to practical applications. It is noticed that the energy conversion and mass transport are the core issues in multi-scale levels of ISSE, no matter of the material design or the system assembly, and the optimization of them is beneficial for the whole process of ISSE. Herein, the research progress is tried to understand and summarize from the material chosen, structural architecture, and system integration with the view of energy and mass transfer. Furthermore, the successful integration of thermoelectric conversion, simultaneous water-hydrogen cogeneration, and metal salt recovery has concurrently enhanced the efficiency of energy utilization. Furthermore, a collaborative operation framework integrating discrete water networks and ISSE technology has been predicted. Through AI empowerment and modularized design, it eventually forms a smart water cycle system with the trinity of "water collection-purification-cogeneration." At the end of this review, the thoughts on the development of ISSE are also provided.