TiO2 and its binary ZnTiO2 and ternary CdZnTiO2 nanocomposites as efficient photocatalysts for the organic dyes degradation
Shakeel Khan, Muhammad Sadiq, Dae-Sung Kim, Mahboob Ullah, Niaz Muhammad
Abstract
Abstract Large band gap and high electron–hole pair recombination rate limits practical application of TiO 2 as a photocatalyst. Different methods are developed to remove or minimize the aforementioned limitations of TiO 2 . In this study, TiO 2 nanoparticles were coupled with ZnO and CdO to address the above-mentioned limitations and hence to enhance the photocatalytic activity of TiO 2 . TiO 2 , ZnTiO 2 and CdZnTiO 2 nanocomposites were synthesized by simple co-precipitation method. The as-synthesized materials were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), energy-dispersive X-ray (EDX), X-ray diffraction (XRD), Brunauer–Emmett–Teller (BET) and UV–visible spectrophotometry. Morphological analysis revealed that neat TiO 2 is mostly agglomerated in spherical form. Their coupling with ZnO and CdO has increased the particle size. TEM analysis showed that CdZnTiO 2 is highly crystalline having uniform mixing of CdO and ZnO particles with TiO 2 in the ternary nanocomposite. The TEM images also showed that the sizes of the entire ternary CdZnTiO 2 nanocomposites are mostly below 50 nm. XRD analysis confirmed the anatase TiO 2 , while the UV–visible analysis revealed the shifting toward higher wavelength. The band gap energy of TiO 2 (2.65 eV) was decreased to 2.64 and 2.49 eV for ZnTiO 2 and CdZnTiO 2 , respectively. The photodegradation results revealed that TiO 2 , ZnTiO 2 and CdZnTiO 2 degraded about 82, 90 and 94% methylene blue dye, respectively, within 120 min. Similarly, the CdZnTiO 2 degraded 96% methyl orange dye within 100 min. It was observed that photodegradation of the dyes increases by increasing photocatalyst dosage and pH of the medium.