The role of micro-nano pores in interfacial solar evaporation systems – A review

Access to clean water is one of the global grand challenges. Using heat energy converted from solar energy to evaporate seawater is a potential approach to mitigate the shortage of fresh water. Interfacial solar evaporation systems employing micro-nano pores in photothermal layers demonstrate enhanced solar energy absorption, heat energy management and water transportation. The review analyzes these systems from the perspective of micro-nano pores for the first time. The basic principles and process of this photothermal evaporation process is presented followed by a review of potential pores such as natural and artificial structures. Then the roles of porous structures are detailed, and this review also points out the ideal pores in photothermal layer. Applications such as seawater desalination, heavy metal removal and steam sterilization are briefly outlined. The review identifies several challenges in the present researches such as how the size, porosity, shape and wettability affect evaporation in mechanisms. Furthermore, the thermal and flow field in the pores should be coupled and consistent with the actual situation. A reliable unified measurement and calculation method is required for making comparison of different results. The micro-nano porous structures need to be stable over a long time and the problem of salt precipitation needs to be addressed. Exploring those issues further would speed the development and practical applications of interfacial solar evaporation systems with micro-nano structures.