TiO2 and its binary ZnTiO2 and ternary CdZnTiO2 nanocomposites as efficient photocatalysts for the organic dyes degradation

Abstract

Large band gap and high electron–hole pair recombination rate limits practical application of TiO2 as a photocatalyst. Different methods are developed to remove or minimize the aforementioned limitations of TiO2. In this study, TiO2 nanoparticles were coupled with ZnO and CdO to address the above-mentioned limitations and hence to enhance the photocatalytic activity of TiO2. TiO2, ZnTiO2 and CdZnTiO2 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 TiO2 is mostly agglomerated in spherical form. Their coupling with ZnO and CdO has increased the particle size. TEM analysis showed that CdZnTiO2 is highly crystalline having uniform mixing of CdO and ZnO particles with TiO2 in the ternary nanocomposite. The TEM images also showed that the sizes of the entire ternary CdZnTiO2 nanocomposites are mostly below 50 nm. XRD analysis confirmed the anatase TiO2, while the UV–visible analysis revealed the shifting toward higher wavelength. The band gap energy of TiO2 (2.65 eV) was decreased to 2.64 and 2.49 eV for ZnTiO2 and CdZnTiO2, respectively. The photodegradation results revealed that TiO2, ZnTiO2 and CdZnTiO2 degraded about 82, 90 and 94% methylene blue dye, respectively, within 120 min. Similarly, the CdZnTiO2 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.