Polyoxometalates-Modulated Hydrophilic-Hydrophobic Composite Interfacial Material for Efficient Solar Water Evaporation and Salt Harvesting in High Salinity Brine

Abstract

Solar vapour generation (SVG) represents a promising technique for seawater desalination to alleviate the global water crisis and energy shortage. One of its main bottleneck problems is that the evaporation efficiency and stability are limited by salt crystallization under high-salinity brines. Herein, we demonstrate that the 3D porous melamine-foam (MF) wrapped by a type of self-assembling composite materials based on reduced polyoxometalates (i.e. heteropoly blue, HPB), oleic acid (OA) and polypyrrole (PPy) (labeled with MF@HPB-PPyn-OA) can serve as efficient and stable SVG material at high-salinity. Structural characterizations of MF@HPB-PPyn-OA indicate that both hydrophilic region of HPBs and hydrophobic region of OA co-exist on the surface of composite materials, optimizing the hydrophilic and hydrophobic interfaces of the SVG materials, and fully exerting its functionality for ultrahigh water-evaporation and anti-salt fouling. The optimal MF@HPB-PPy10-OA operates continuously and stably for over 100 h in 10 wt% brine. Furthermore, MF@HPB-PPy10-OA accomplishes complete salt-water separation of 10 wt% brine with 3.3 kg m-2 h-1 under 1-sun irradiation, yielding salt harvesting efficiency of 96.5%, which belongs to the record-high of high-salinity systems reported so far and reaches zero liquid discharge. Moreover, the low-cost of MF@HPB-PPy10-OA (2.56 $/m2) suggests its potential application in the practical SVG technique.

A photocatalyst with an enhanced Schottky effect and an efficient electron-transfer channel fabricated by assembling Ni–WC heterojunction nanoparticles on g-C3N4 for highly efficient removal of chlorophenols

“…Polyoxometalates (POMs), as special kinds of nanosized transition metal-oxo clusters with abundant elemental compositions and adjustable structures, 12,26,[32][33][34][35] have been proven to be a promising candidate for the construction of multi-component catalysts. 26 To engineer the Schottky heterostructure among the g-C 3 N 4 semiconductor, Ni NPs and WC species, the pre-assembly of Ni and W elements at the molecular level precursor is necessary.…”