Solar-assisted desalination based on photothermal conversion effect: A review

The global scarcity of freshwater resources presents an urgent need for efficient desalination technologies. This review identifies and evaluates the most effective photothermal materials (PTMs) that support solar-driven water evaporation for desalination, highlighting their potential to sustainably meet the growing water demands. Photothermal technology is selected due to its promising efficiency, derived from optimized light absorption and photothermal conversion. Key PTMs, including metal-, metal oxide-, polymer-, and carbon-based materials, are examined for their impact on enhancing evaporation rates, system designs, and energy integration possibilities. The study provides insights into the design parameters essential for PTM-based desalination systems, such as light absorption efficiency, wettability, and stability. Among different locations of PTM integration including bottom-fixed PTM layer, volumetric systems, and interfacial systems with floating PTMs, the last one benefits from 100 % conversion efficiency. The highest water evaporation rate of 5.6 kg/(m2.h) is obtained by fabricating a multilayer evaporator and coupling optimum carbon black-cellulose ester with polystyrene foam and air-laid paper. Polypyrrole supramolecular network/packed photothermal aerogel and Ti2O3/Polyvinyl alcohol-based solar evaporator rank next in terms of the water evaporation rate (3.6 and 3.59 kg/m2.h, respectively) under 1-sun illumination. While significant advancements in material performance and design have been achieved, challenges remain, especially in scalability and environmental impact. This review suggests avenues for future research, including developing more affordable, sustainable materials and advanced system configurations to maximize desalination efficiency and minimize environmental costs.