LAUSR

Abstract We fabricated 5,10,15,20-tetra(4-pyridyl)porphyrinatozinc(II) (ZnTPyP) fibers by utilizing surfactant-assisted method with cetyltrimethylammonium bromide (CTAB). The ZnTPyP fibers became longer as molar ratio of CTAB to ZnTPyP (γ) increased. In the case of γ ≥ 50, the Soret band of ZnTPyP monomer was observed after stirring for 1 h and was split into two peaks after the aging at 40 °C for more than 5 days. On the other hand, such split peaks were observed without the aging when the γ value was 10 or 20. These findings suggest that CTAB interacts with the ZnTPyP monomer in aqueous solution to form micelles, and the fibers are gradually constructed by self-assembling the stabilized ZnTPyP monomer. Photocatalytic activity of the ZnTPyP fibers was evaluated for the degradation of rhodamine B (RhB) in water under visible light (VL) irradiation. The highest photocatalytic activity was obtained at γ = 150–300, indicating that the fibers with 1.3–2.0 μm were the most suitable as photocatalyst. When air was bubbled in the reaction solution, the photocatalytic activity was higher than that under N2 bubbling. However, absorption peak attributed to the ZnTPyP fibers decreased under air bubbling although it remained almost constant under N2 bubbling. These results suggest that the ZnTPyP fibers can act as photocatalyst and active oxygen species such as O2•− radical might decompose the ZnTPyP fibers. Kinetic studies were performed to clarify the degradation mechanism of RhB under the experimental condition where the decomposition of the ZnTPyP fibers was negligible.