Ceria/Gold Nanoparticles in Situ Synthesized on Polymeric Membranes with Enhanced Photocatalytic and Radical Scavenging Activity

This study reports a novel two-step approach to fabricate poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP)/cerium oxide (CeO2) nanocomposite fibrous membranes. The fabrication method is based on the combination of the electrospinning of a polymer/cerium salt solution and the subsequent in situ thermally activated conversion of the salt in CeO2 nanoparticles, directly in the polymeric fibers. This procedure leads to a homogeneous filler dispersion not only in the bulk of the polymeric fibers but also on their surface, thus conferring to the system remarkable properties, such as radical scavenging and photocatalytic activity. These properties are further improved by the decoration of the CeO2 with gold nanoparticles, formed upon the dipping of the solid PVDF-HFP/CeO2 fibers in a gold precursor solution and their subsequent thermal treatment, thanks to the modification of the Ce3+/Ce4+ ratio and the absorption spectrum shifted toward visible wavelengths. Specifically, the presence of Au on the surface of the PVDF-HFP/CeO2 fibrous membranes dramatically enhances the radical scavenging activity, which reaches up to 90% of scavenged radicals in 24 h. In addition, the photocatalytic degradation activity is remarkably improved, making possible to photodegrade organic dyes under visible light. Such performances, in combination with the straightforward fabrication method, the high surface area, the light weight, and flexibility, offered by the polymeric fibers make the presented system a valuable alternative to the existing ceria-based systems, e.g., ceramic supported, opening up an innovative route to fabricate multifunctional membranes for water purification or bioapplications due to the CeO2 antioxidant properties. ©