Quaternized zinc(II) phthalocyanine-sensitized TiO2: surfactant-modified sol–gel synthesis, characterization and photocatalytic applications

TiO2 nanoparticles and zinc phthalocyanine-sensitized TiO2 (ZnPc/TiO2) nanocomposite were synthesized in the presence and absence of Triton X100 (a nonionic surfactant) by a modified sol–gel method to improve the photocatalytic activity of TiO2 under near visible light (365 nm). A novel quaternized ZnPc molecule was used as sensitizer. Prepared nanoparticles and nanocomposite were characterized by scanning electron microscopy, energy dispersive analysis, X-ray diffractometry, transmission electron microscopy (TEM), Brunauer–Emmett–Teller, thermogravimetry analysis, and UV–vis–NIR. The results demonstrated that the ZnPc was successfully loaded on the TiO2 nanoparticles and the nanocomposite possesses the anatase crystalline phase with the specific surface area of 110.04 m2 g−1. The TEM micrograph showed that the average grain crystal size is 5–15 nm. ZnPc in the TiO2 structure shifted the absorption edge to visible region. The photocatalytic activities of prepared photocatalysts (ZnPc/TiO2, ZnPc/TiO2-TX100, TiO2, and TiO2-TX100) were evaluated for degradative removal of methyl orange and reductive removal of Cr(VI) ions as test pollutants. Results of photocatalytic removal revealed that the ZnPc/TiO2-TX100 has shown much more photocatalytic efficiencies than the ZnPc/TiO2 prepared without TX100 and neat TiO2 prepared with or without TX100. Therefore, this sol–gel method modified with TX100 is useful in the preparation of nanostructure ZnPc/TiO2 with high photocatalytic activity and higher surface area.