Tungsten Oxide-Blended PVDF-HFP Electrospun Nanofiber Membranes for Solar-Driven Interfacial Water Evaporation

Solar-assisted thin film evaporation is a promising step toward achieving renewable-energy powered desalination. Electrospun nanofiber membranes (ENMs) have high porosity, surface area, mechanical strength, and tunable nanofiber structure, which make them suitable for membrane desalination. In this work, electrospun poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP) nanofiber membranes loaded with tungsten oxide (WO₃) nanoparticles were fabricated and tested for solar-driven interfacial water evaporation. The ENMs, composed of three layers, and the WO₃ nanoparticles were incorporated on the top layer via blending in order to maximize their surface exposure. These layers were then heat-pressed for dimensional stability. Detailed characterizations were performed applying goniometric, microscopic, gravimetric, and spectroscopic methods, and evaporation performance was tested in a laboratory-scale setup comprising a solar simulator. All ENMs exhibited a randomly oriented, smooth microporous structure, and EDS mapping confirmed the uniform distribution of WO₃ nanoparticles on the surface. All ENMs were hydrophobic and have high (>20 Psi) liquid entry pressure values, indicating their potential application in membrane distillation. Furthermore, blended ENMs (P1W−P8W) exhibited enhanced mechanical strength, improved UV/Vis absorption, and have a thickness similar to that of pristine ENM. Finally, the photothermal evaporation using deionised water illustrated the enhanced performance of blended ENMs. These findings will advance the photothermal desalination processes, which can minimize the temperature polarization and improve the energy efficiency of conventional membrane distillation.