Metal Organic Framework-Derived Bi2O3-ZnO/TiO2 Nanofibers Catalysts for Enhanced Photodegradation of Methylene Blue

This work introduces innovative Bi2O3-ZnO/TiO2 (BZT) composite photocatalysts, developed via a simple electrospinning technique. The incorporation of Zn2+ and Bi3+ ions was confirmed through high-resolution transmission electron microscopy and X-ray photoelectron spectroscopy (XPS). XPS analysis confirmed the presence of Zn and Bi elements on the surface of TiO2 nanofibers, with oxidation states of + II and + III, respectively. The band gaps, estimated through the Kubelka-Munk function and ultraviolet-visible diffuse reflectance spectroscopy, decreased from 3.18 eV for pristine TiO2 to 2.9 eV for the 1%Bi2O3-ZnO/TiO2 (1BZT) composites, resulting in improved light-harvesting capabilities. Photocatalytic performance studies, particularly methylene blue degradation under visible light, revealed notable improvements for Bi2O3-ZnO/TiO2 systems compared to ZnO/TiO2 and TiO2. The 1%Bi2O3-ZnO/TiO2 heterostructure was found as efficient photocatalyst with 98% photodegradation of MB. The maximum rate constant, 0.0234 min(- 1), was observed for 1BZT nanofibers, which was 4.97 and 16.7 times greater than those of ZnO/TiO2 and TiO2, respectively. This enhancement highlights the synergistic effect between Zn2+ and Bi3+, alongside the enhanced visible light absorption by Bi3+, which collectively elevated the photocatalytic efficiency. The heterojunction formed among Bi3+, Zn2+, and Ti4+ significantly facilitated the separation of photogenerated charge carriers, which is essential for high photocatalytic efficiency. Quenching experiments confirmed the important roles in the photocatalytic degradation of MB were played by (OH)-O-center dot and O-center dot(-) (2) rather than the h(+) radical under sun light. The 1%Bi2O3-ZnO/TiO2 photocatalyst exhibited the highest level of activity and excellent reusability, retaining its photocatalytic performance over multiple cycles.