Porphyrin-TiO2 encapsulated ZIF-8/PAN-derived porous carbon nanofiber ternary photocatalyst with enhanced photodegradation efficiency through synergistic effect

Abstract

In this study, TiO2 nanoparticle-encapsulated ZIF-8/polyacrylonitrile (PAN)-derived porous carbon nanofibers (PCNFs) have been synthesized by combining electrospinning and hydrothermal methods, which were then sensitized with tetra-carboxyphenylporphyrin copper(Ⅱ) (CuTCPP) to obtain porous carbon nanofibers ternary photocatalyst (PCNFs@TiO2-CuTCPP) for photocatalytic degradation of pollutants. The structure and composition of the samples were characterized by XRD, FT-IR and XPS. The internal pore structure of PCNFs@TiO2-CuTCPP and the uniformity of the outer layer wrapped by TiO2 nanoparticles can be observed by SEM and HRTEM. PCNFs@TiO2-CuTCPP has a high specific surface area (136.68 m2/g), which enables it to have excellent adsorption activity for model dye-Rhodamine B (RhB, 47.2 %, 4.7 × 10−4 mol/g), Methylene Blue (MB, 27.7 %, 2.8 × 10−4 mol/g) and Tetracycline hydrochloride (TC, 38.9 %, 3.1 × 10−4 mol/g) within 30 min. Photocatalytic experiments showed that the degradation rates of RhB and MB by PCNFs@TiO2-CuTCPP as photocatalyst were 95.4 %, 92.8 % and 89.9 %, respectively, after 180 min of visible light irradiation. PCNFs@TiO2-CuTCPP was continuously reused for four cycles without significant photoactivity loss and structural changes. Furthermore, the crucial role of .O2−, 1O2 and .OH were confirmed by active species capture experiments, and the photocatalytic mechanism under visible light was proposed. Above all, this study prepared a recyclable TiO2-based porous carbon nanofibers photocatalyst and provided a new idea for the effective modification of TiO2 in the field of photocatalysis.