An integrated solar absorber with salt-resistant and oleophobic based on PVDF composite membrane for solar steam generation

Improving the salt resistance and anti-fouling of photothermal materials is essential for practical application of solar interfacial evaporation technology. In this article, a double-layered dual-function interfacial evaporation system (named as M-SIE) with self-desalting and oil repellency is reported, which is fabricated by carbon black, polyvinylidene fluoride, and nano sponge. The as-prepared M-SIE shows a high solar energy conversion efficiency of 81.7%–83.1%, which is due to the dual function of light absorption (Ca. 90%) and superhydrophilicity. The superhydrophilicity and floatability in water endow the nano sponge pumping water continuously and greatly promote the dissolution of salt accumulation, e.g. 1 g NaCl on polyvinylidene fluoride composite membrane can be eliminated completely in a short time. The solar energy conversion efficiency of M-SIE was measured to be 78.9%–79.2% in 20 wt% NaCl, and the solar energy conversion efficiency can reach to 80.4% in an aqueous solution containing 6% n-hexadecane. Compared with the most existing interface evaporation systems, the M-SIE system has the advantages of simple fabrication, highly efficiency, stability, and portability. Moreover, the salt and oil resistance make the M-SIE can serve as a high-performance integrated evaporation system with great potential for operation under different water environments such as seawater or oily wastewater, and so on.