Solar energy is now emerging as one of the most promising sustainable energy sources, as it is clean and can be supplied without any environmental pollution compared with other forms of energy. Abundant solar energy makes solar-driven evaporation a promising approach for water desalination and purification. In a conventional solar-driven evaporation system, bulk water is heated to a high temperature to generate water vapor, resulting in a slow response to sunlight and heat loss to the bulk water or the external environment.
In 2011, researchers demonstrated a floating interfacial solar-driven evaporation structure, which does not require significant capital investment in high-cost permanent construction or land use. However, significant challenges remain for achieving a higher evaporation rate and high water quality together with a cost-effective and easy-to-manufacture device to provide a feasible solar-driven steam generation system.
Northeastern researchers have developed a novel paint (Black 3.0) that can be applied to a floating interfacial solar-driven evaporation device serving as the photo‑thermal conversion material combined with a sheet of melamine foam (MF). A sheet of hot-pressed MF serves as an ideal elastic skeleton material when sprayed with Black 3.0, serving as a solar absorber to efficiently absorb and convert the solar radiation into heat. To achieve a high evaporation performance and high solar-thermal energy conversion efficiency, a self-floating interfacial evaporation structure with a 2D water path is demonstrated to localize solar-thermal heat generation to the interface. Under one-sun solar illumination (1000 W/m2) without solar concentration, the evaporation device yields an excellent evaporation rate as high as 2.48 kg/m2h. The proposed device demonstrates a superb performance with cost-effectiveness, as well as chemical stability in wide degrees of acidity and alkalinity.