Preparation, Characterization And Catalytic Applications Of Metal Nanoparticle-Loaded Composite Electrospun Nanofibrous Materials

With the development of nanotechnology in different research fields, more and more effort has been devoted to the preparation and application of nano materials. Nanofibers which is a new kind of emerging nanomaterials have been applied in catalytic, environment remediation, tissue engineering, sensor and other areas.In this study, the author prepared two kinds of nanofibers (polyethyleneimine (PEI)/polyvinyl alcohol (PVA) nanofibers, polyacrylic acid (PAA)/PVA nanofibers). Then we immobilized the metal nanoparticles onto the nanofibers by in-situ synthesis, physical absorption and chemical reaction. By means of SEM, EDS, TEM, FTIR, TGA, ICP-OES and UV-vis, we characterized the metal nanoparticle (NP)-containing electrospun nanofibers and their catalytic activities. Generally, our work consists of the following two parts:First, we creatively immobilized Au@Ag core-shell NPs with synergistic catalysis activity onto electrospun PEI/PVA nanofibers by in-situ synthesis. The small-size and narrow size distribution of Au@Ag core-shell NPs reveal that the nanofibrous structure is able to efficiently reduce the particle aggregation. In the study, the water-stable PEI/PVA nanofibrous mats were complex with AuCl4-anions and Ag+anions separately via the binding with the free amine groups of PEI for subsequent formation and immobilization of Au NPs and Ag NPs. We show that the water-stable nanofibrous mats can effectively catalyze the transformation of4-nitrophenol to4-aminophenol. This novel approach to fabricating metal core-shell NP-immobilized polymer nanofibers with the high porosity and great reusability should render them to be applied in various areas, such as catalysis, sensing, and environmental remediation.Second, we report here a facile approach to assembling low generation poly(amidoamine)(PAMAM) dendrimer-stabilized gold NPs (Au DSNPs) onto eletrospun polymer nanofibrous mats for catalytic applications. In this study, Au DSNPs formed using amine-terminated generation2PAMAM dendrimers as stabilizers were assembled onto electrospun PAA/PVA nanofibrous mats either through electrostatic interaction or through covalent EDC coupling reaction. The assembly of Au DSNPs with a mean diameter of5.4nm onto the electrospun nanofibrous mats was characterized via different techniques. The catalytic activity of the Au DSNP-assembled nanofibrous mats was evaluated by transformation of4-nitrophenol to4-aminophenol. We show that both approaches enable efficient assembly of Au DSNPs onto the nanofiber surfaces and the formed Au DSNP-containing nanofibers formed via both approaches have excellent catalytic activity and reusability. However, the Au DSNP-assembled nanofibers via electrostatic physical interaction display much higher catalytic activity than those formed via the chemical assembly approach. The facile dendrimer-mediated assembly approach to modifying electrospun nanofibers may be used to fabricate other composite nanofiber systems for applications in catalysis, sensing, and biomedical sciences. Compared to the Au@Ag core-shell NP-containing electrospun PE1/PVA nanofibers by in-situ synthesis and Au DSNP-containing PAA/PVA nanofibers prepared by chemical reaction, Au DSNP-containing PAA/PVA nanofibers prepared by physical self-assembly displays better catalytic activity.