Co_2.67S₄-Based Photothermal Membrane with High Mechanical Properties for Efficient Solar Water Evaporation and Photothermal Antibacterial Applications

The lack of freshwater resources, or the freshwater crisis, is an important issue in the resource field. One potential green and sustainable method to solve this problem is to implement solar energy-driven water evaporation to collect freshwater. Capitalizing on the low cost, high production yield, and simplified fabrication process properties of nonstoichiometric Co2.67S4 nanoparticles, we strategically designed and synthesized a Co2.67S4-deposited Teflon (PTFE) membrane for realizing efficient solar water evaporation and photothermal antibacterial properties under light irradiation. Compared with previously reported cellulose acetate and poly(vinylidene fluoride) membranes, the PTFE membrane displayed significantly enhanced mechanical properties. Additionally, a Co2.67S4-deposited PTFE membrane with a hydrophobic treatment (termed as the Final-PTFE membrane) exhibited excellent durability. The light-to-heat conversion efficiency (η) of water evaporation reached a value of 82% for our as-prepared Final-PTFE membrane under two sun irradiation conditions. Moreover, the antibacterial mechanism observed by scanning electron microscopy was attributed to the thermal effect, which damaged the cell wall of bacteria. Our work highlights the great potentials of the Final-PTFE membrane as a versatile system for implementing solar energy-driven photothermal water evaporation and water purification.