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Design and Synthesis of Polymeric Nanofibers/ ZnO Nanorods/ Silver Nanoparticles for Photocatalytic Degradation of Organic Pollutants

Asghari Sarabi, Ghazaleh | 2026

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  1. Type of Document: Ph.D. Dissertation
  2. Language: Farsi
  3. Document No: 58857 (48)
  4. University: Sharif University of Technology
  5. Department: Institute for Nanoscience and Nanotechnology
  6. Advisor(s): Moshfegh, Alireza; Bagheri, Habib; Samadi Amin, Morasae
  7. Abstract:
  8. This study aims to synthesis and fabricate polyacrylonitrile (PAN) polymeric nanofibers via electrospinning, grow zinc oxide (ZnO) nanorods on this flexible substrate, and subsequently activate the system under visible-light irradiation through the deposition of silver (Ag) nanoparticles. The resulting hierarchical structure was investigated for its application in the photocatalytic degradation of organic pollutants under various light sources, with particular emphasis on natural sunlight, as well as for elucidating the underlying photodegradation mechanisms. One of the major challenges associated with heterogeneous photocatalysts in practical applications is their difficult separation from the reaction medium, which necessitates additional processes such as filtration and centrifugation procedures that are impractical for large volumes of industrial wastewater. To overcome this limitation, photocatalytic semiconductors were immobilized onto a porous and flexible nanofibrous substrate in this work. This strategy not only facilitates catalyst recovery but also enables the formation of self-standing and floating structures, allowing repeated use and enhanced operational efficiency, thereby offering a promising approach for industrial applications. Another critical challenge in this field is the activation of photocatalysts under natural sunlight and the improvement of reaction efficiency. Due to its wide band gap, ZnO is intrinsically inactive under visible light. However, considering the climatic conditions of Iran and the high number of sunny days, the development of visible-light-responsive photocatalysts is of particular importance. In this regard, the activation of ZnO under visible light has been achieved through the deposition of Ag nanoparticles. Moreover, ZnO exhibits piezoelectric properties, while silver nanoparticles possess plasmonic characteristics; the synergistic interaction between these two components effectively suppresses electron-hole recombination, leading to enhanced photocatalytic performance. Photoelectrochemical studies revealed that the Ag NPs/ZnO NRs/PAN NFs exhibited higher photocurrent density and improved stability compared to ZnO NRs/PAN NFs. Furthermore, the Ag-modified sample demonstrated photocatalytic reaction rate constants that were approximately 2.2, 2.6, 1.7, and 1.6 times higher for the photo-degradation of methylene blue (MB), rhodamine B (RhB), acid orange 7 (AO7), and tetracycline (TC), respectively, under ultraviolet irradiation. In addition, the Ag-modified photocatalyst showed a significant enhancement in MB degradation under various light sources, including LED light, solar simulated sunlight, and natural sunlight. Under natural sunlight irradiation, this sample was capable of removing approximately 83.5% of MB and 60.4% of RhB within 1 hour for the mixture of MB and RhB, demonstrating its superior photocatalytic activity under practical solar conditions. Moreover, the combined piezoelectric effect of ZnO and the plasmonic properties of silver NPs enhanced the photocatalytic degradation efficiency of MB under UV light irradiation and ultrasonic waves by approximately 2.2 times. Mechanistic investigations revealed that the generation of plasmonic hot electrons on silver NPs plays a key role in improving the photocatalytic performance. In addition, the fabricated photocatalytic layers exhibited high flexibility and reusability, and demonstrated good stability after five photocatalytic degradation cycles of MB and RhB under UV light irradiation
  9. Keywords:
  10. Zinc Oxide ; Electrospinning ; Polyacrylonitrile ; Dye ; Tetracyclines ; Silver Nanoparticles ; Piezo-Photocatalysis ; Photocatalyst

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