CoWO_4-x -Based Photothermal Membranes for Solar-Driven Water Evaporation and Eutrophic Lake Water Purification

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.