Metalloporphyrin-sensitized titania/silica/iron oxide nanocomposites and their photocatalytic activities

Abstract

New nanomaterials of the magnetic visible light active photocatalysts, tetra(4-carboxyphenyl)porphyrin (TCPP) with different metals [Mn(II), Fe(III), Cu(II), Zn(II) and metal-free] in the center adsorbed on titania-silica-iron oxide superparamagnetic composites (TSI) were synthesized successfully. The photocatalytic activities in methylene blue (MB) degradation were determined under incandescent lamp for 3 h. Their characteristics have been identified using UV-visible spectroscopy, X-ray diffractometry (XRD), transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FT-IR), and X-ray photoelectron spectroscopy (XPS). The photodegradation results revealed that the metalloporphyrin sensitization helped TSI to absorb the light in visible region. Titania-silica-iron oxide nanomaterials with copper(II) tetra(4-carboxyphenyl)porphyrin (CuTCPP) can significantly eliminate methylene blue (MB) and Escherichia coli (E. coli) upon 3 h of irradiation. The four-cycled reuse without regeneration of the CuTCPP-TSI results supported the great reusability with the ease in magnetic separation due to high magnetic response of the nanocomposites. The photodegradation activity is not only dependent on the type of metal in metalloporphyrin, but many factors including content of the loaded porphyrin also influence the activity. The suitable condition for CuTCPP-TSI nanocomposite preparation is 0.01 mmol of CuTCPP per 50 mg of TSI using stirring at 60 οC for 12 h. Consequently, the visible light activated photocatalysts were favorably synthesized and able to apply in photooxidative reaction in various applications.