Servicenavigation

Project Details

Back

Projekt Print View

Electrospun Nanofibers with Embedded Yolk-Shell Particles for Catalytic Applications

Applicant Privatdozentin Dr. Petra Uhlmann, since 9/2022
Subject Area Preparatory and Physical Chemistry of Polymers
Synthesis and Properties of Functional Materials
Physical Chemistry of Molecules, Liquids and Interfaces, Biophysical Chemistry
Polymer Materials
Term from 2017 to 2023
Project identifier Deutsche Forschungsgemeinschaft (DFG) - Project number 323249705
 
Final Report Year 2023

Final Report Abstract

The ultimate goal of this project was the fabrication of fibrous (photo)catalyst functionalized with yolk-shell type particles using electrospinning technique and investigation of their catalytic performance. The experimental work within this project was subdivided into several parts, some of which were also extended with theoretical modeling and numerical simulations. The first part of the project was focused on encapsulation of catalytically active nanoparticles (NP) in pre-formed block copolymer (BCP) micelles towards NP/BCP hybrid micelles with welldefined and controllable NP distribution. For the preparation of BCP micelles we used polystyrene-block-poly(4-vinyl pyridine) (PS-b-P4VP) of varied of varied composition and molecular weight. We studied in detail the process of PS-b-P4VP micelle formation in solvents which are selective for P4VP block. Main findings from this part of project work are presented in our paper published in Polymers.[I] As encapsulated nanocatalyst, we used nanosized gold NPs (AuNPs) which were synthesized via standard wet chemistry methods and modified with PS ligand to make them compatible with PS block of PS-b-P4VP. The PS-coated AuNPs were encapsulated in the PS core of pre-formed PS-b-P4VP micelles driven by competitive solvation of PS, P4VP blocks and AuNPs by two inversely selective solvents. We found that relatively large PS-coated AuNP are entrapped within the core of pre-formed BCP micelles. This is very interesting phenomena which has never been described and addressed before. We also found that Au(PS)@PS-b-P4VP hybrid micelles comprising a single AuNP in micellar core are obtained in a certain range of solvent mixture composition. We investigated the NP encapsulation process in detail, both experimentally and theoretically using Molecular Dynamic (MD) simuations. For theoretical studies, we constructed a Most significantly, based on our studies we presented two possible mechanism of hybrid micelles formation: single chain (or one-by-one) adsorption and anchoring-fusion mechanism. We point out that NP encapsulation process is readily reproducible and, on the same time, very sensitive to experimental conditions. Our findings are very important for better understanding of thermodynamics and kinetics of cooperative self-assembly processes taking place in NP/BCP mixtures under selective solvation conditions. Using an acid-catalyzed sol-gel process, Au(PS)@PS-b-P4VP hybrid micelles were further converted into Au(PS)@PS-b-P4VP@SiO2 core-shell particles comprising a single AuNP core. Our findings related to this part of the project are presented in our article published in Macromolecules.[IV] The second and third parts of the project work were dedicated to the fabrication of fibrous catalysts comprising various types of Au-based nanoparticlulate inclusions integrated into the fiber walls and investigation of their (photo)catalytic performance, respectively. Using a singlenozzle and co-axial electrospinning techniques, we were successful in fabrication of various types of titania-based regular and core-shell electrospun nanofibers (NFs), respectively, functionalized with different kinds of Au-based particles as inclusions. Electrospun NFs were further converted into Au-functionalized porous TiO2 fibrous photocatalyst. Our results on herein developed electrospun fibrous photocatalysts and related photocatalytic studies are reported in RSC Adv. Another manuscript containing experimental and modeling results from this part of the project work is currently under preparation.[VII] The most interesting findings are related to the TiO2 nanofibers (NFs) comprising Au@void and Au@void@SiO2 type nanoparticles as inclusions, which were prepared using a combination of above discussed BCP templating method, sol-gel processing, coaxial electrospinning and calcination step. Herein, Au(PS)@PS-b-P4VP and Au(PS)@PS-b-P4VP@SiO2 additives in electrospun solutions were used as precursors in the formation of Au@void and Au@void@SiO2 nanoparticles, respectively. Thus, we have developed a strategy for fabrication of porous TiO2 NFs comprising Au@void or Au@void@SiO2 inclusions in their walls. The catalytic and photocatalytic activity of the resulting Au@void/TiO2 and Au@void@SiO2/TiO2 NFs were systematically investigated using several model reactions and under various illumination conditions. Interestingly, the Au@void@SiO2/TiO2 fibrous catalyst exhibited strong 4 enhancement of catalytic and photocatalytic performance as compared to Au@void/TiO2 type catalyst, despite of the presence of SiO2 shell separating Au NPs from TiO2 support. Subsequent finite-difference time-domain (FDTD) based numerical simulations performed on respective constructed models suggest that the origin of such enhancement in photocatalytic activity may originate from the surface plasmon resonance confinement effects, being more pronounced for Au@void@SiO2-loaded TiO2 NFs as compared to Au@void case. The presented approach is a promising route for the fabrication of highly active fibrous (photo)catalytic systems where the added photocatalytic activity of titania could be of further significance.

Publications

 
 

Additional Information

© 2025 DFG Disclaimer / Copyright / Privacy Policy

Textvergrößerung und Kontrastanpassung