CoWO(4–x)-Based Photothermal Membranes for Solar-Driven Water Evaporation and Eutrophic Lake Water Purification

[Image: see text] Solar-driven water evaporation has been proven to be a promising and efficient method for the energy crisis and clean water shortage issues. Herein, we strategically design and fabricate a novel nonstoichiometric CoWO(4–x)-deposited foam nickel (NF) membrane (CoWO(4–x)@NF) that possesses all the desirable optical, thermal, and wetting properties for efficient water evaporation and purification. The broadband absorption of CoWO(4–x) nanoparticles (NPs) obtained by hydrogen reduction contributes to light-to-heat conversion, while NF with a three-dimensional porous structure can support CoWO(4–x) NPs and ensure the rapid flow of water molecules during the water evaporation process. We systematically explore and compare the outdoor water evaporation performance of the pure water group, NF group, and CoWO(4–x)@NF group, and the results show that CoWO(4–x)@NF performs well under natural sunlight irradiation (water evaporation: 2.91 kg m(–2)). Significantly, under solar irradiation, the remarkable reduction of Cyanophyta and Euglenophyta in lake water is achieved in the CoWO(4–x)@NF membrane-administered group, and these two algae are the main factors for eutrophication of the lake water. Our work highlights the great potentials of the CoWO(4–x)@NF membrane as a device for realizing outdoor solar energy-driven water evaporation and proposes a new strategy for purifying the eutrophication of the lake water.