Enhanced photocatalytic activity in metal phthalocyanine-sensitized TiO2 nanorods

Abstract

Two novel metal phthalocyanines (Zn Tetra(butylformate-phenoxy)phthalocyanine (ZnTBPP) and Zn Tetra(tert-butyl-phenoxy)phthalocyanine (ZnTTPP)) were synthesized. Besides, TiO2 nanorods (PN) are prepared through the hydrothermal method. The synthesized metal phthalocyanines are used to sensitize TiO2 nanoparticles (P25) and PN. Then, four types of metal phthalocyanine-sensitized TiO2 composite photocatalytic materials (ZnTBPP/P25, ZnTTPP/P25, ZnTBPP/PN and ZnTTPP/PN) are obtained and characterized by methods of X-ray diffraction, scanning electron microscopy, nitrogen adsorption–desorption, Fourier-transform infrared spectroscopy, UV–Vis diffuse reflectance spectroscopy, fluorescence spectra and density-functional theory. At last, the photocatalytic degradation of rhodamine B (RhB) is taken as an example to study the photocatalytic activity of composite photocatalytic materials. The results show that the photocatalytic activity of the composite photocatalytic material is stronger than that of TiO2. This is because in the photocatalytic process, the loading of metal phthalocyanine can expand the material’s photoresponse range and enhance its light absorption performance. At the same time, the metal phthalocyanine can optimize the energy-level structure of the material and reduce the electron–hole recombination. Besides, we found that the photocatalytic activity of nanorods is stronger than that of the nanoparticles because the nanorod structure with a large specific surface area can not only increase metal phthalocyanine load, but also expose more active sites.