Fabrication, characterization and application of phthalocyanine-magnetite hybrid nanofibers

Abstract

Magnetic nanoparticles comprising magnetite (Fe3O4) were functionalized with 3-aminopropyl-triethoxysilane forming amino functionalized magnetite nanoparticles (AMNPs). The amino group allows for conjugation with zinc octacarboxyphthalocyanine (ZnOCPc) or zinc tetracarboxyphthalocyanine (ZnTCPc) via the carboxyl group to form an amide bond. A reduced aggregation of ZnTCPc is observed after conjugation with AMNPs. The thermal stability, conjugation, morphology and the sizes of the nanoparticles and their conjugates were confirmed using thermogravimetric analysis (TGA), Fourier transform infrared spectroscopy (FTIR), transmission electron microscopy (TEM) and Powder X-ray diffractometry (PXRD), respectively. The covalent linkage of AMNPs to ZnOCPc or ZnTCPc resulted in improvement in the photophysical behavior of the phthalocyanines. Improvement in the triplet quantum yield (ΦT), singlet oxygen quantum yield (ΦΔ), triplet lifetime (τT) and singlet oxygen lifetime (τΔ) of the ZnOCPc or ZnTCPc were observed, hence improving the photosensitizers efficiency. The conjugates comprising of zinc octacarboxyphthalocyanine (ZnOCPc) and AMNPs were electrospun into fibers using polyamide-6 (PA-6). This was used for the photodegradation of Orange-G and compared with ZnOCPc-AMNPs in suspension. For ZnOCPc-AMNPs in suspension, it is noteworthy that the catalyst can be easily recovered using an external magnetic field. The singlet oxygen generation increases as we increase the fiber diameter by increasing the ZnOCPc concentration. The singlet oxygen quantum yield is higher for PA-6/ZnOCPc-AMNPs nanofibers when compared to PA-6/ZnOCPc. The rate of degradation of Orange-G increased with an increase in the singlet oxygen quantum yield. Moreover, the kinetic analysis showed that the photodecomposition of Orange-G is a first-order reaction according to the Langmuir-Hinshelwood model.