Fe(III)-natural polyphenols bilayer coatings on fingered citron as a novel photothermal material for sustainable seawater desalination

The fresh water shortage is a big driving force for scientists worldwide to study on seawater desalination. Recently, the solar steam generation (SSG) based on biomass has already attracted a great deal of interest because of its effectiveness and eco-friendliness. In this study, a novel photothermal material for SSG was fabricated by treating fingered citron (FC) with natural polyphenols from green tea extract (GTE) and then with Fe (III) solution to form nano layers of Fe (III) complex on FC surface. Consequently, the developed FC based photothermal material (FCP) exhibited high light absorption capacity. Thanks to its unique structure with honeycomb-like porous pith and scattered linear vascular bundles and hydrophilic property, FCP possessed essential features for good performance of SSG including excellent water transportation, low thermal conductivity, high salt rejection capacity, and stable operation. The FCP based SSG system demonstrated a water evaporation rate of 1.92 kg m−2 h−1 under 1 sun illumination, which is comparable or even superior to those of the reported biomass-based photothermal materials. The simple, cost-effective, and green FCP fabrication technology together with the high water evaporation performance of the FCP based SSG highlight the promising application of FCP in SSG toward sustainable seawater desalination.