Synthesis and characterization of novel unsymmetrical phthalocyanine/TiO2 composites and their evaluation as photocatalysts for degradation of 4-chlorophenol under visible light

Abstract

We prepared novel unsymmetrical A3 B-type zinc and cobalt phthalocyanines bearing monocarboxylic acidgroups on peripheral positions using statistical condensation method, especially designed to anchor on the TiO2 semiconductor surface. The novel complexes were anchored on TiO2 semiconductor to prepare effective dye sensitizedphotoactive composites as heterogeneous catalysts. The results indicated that modified TiO2 nanocrystals possessedonly the anatase phase and MPc-TiO2 photocatalysts with loading amount of dye ca. 8.27 µmol/g TiO2 exhibitstrong visible light absorption. Photocatalytic degradation of 4-chlorophenol (4-CP) under illumination with visiblelight (λ > 400 nm) was tested with the composites prepared. The degradation profile indicates that MPc-modifiedtitania nanocrystals are superior to pristine titania under visible light in terms of photocatalytic effect. Photocatalyticreusability efficiency and the stability of photocatalyst composites were also investigated. Additionally, the effect ofdifferent substituent groups (such as aromatic vs. aliphatic, alkyl chain length) on photocatalytic efficiency was revealedand also compared to our previous works.