Surface and optoelectronic impacts of ZnO/BiVO4/MWCNT nanoheterostructure toward photodegradation of water contaminants

The preparation of ZnO/BiVO4/MWCNT nanoheterostructures by a modified hydrothermal method as a solar active photocatalyst was reported. The prepared nanoheterostructures were characterized by surface and bulk techniques such as: transmission electron microscopy (TEM), X-ray powder diffraction (XRD), X-ray photoelectron spectroscopy (XPS), UV−vis spectroscopy, Fluorescence lifetime (FLT) and Isoelectric point (IEP). The produced nanoheterostructures' UV–vis spectra indicated that they are widely absorbed in the visible region with bandgap values in the range of 2.38–3.28 eV. When compared to BiVO4, the heterostructured photocatalyst's average fluorescence lifetime was increased from 1.28 to 1.90 ns, indicating that the ZnO/ BiVO4/MWCNT nanoheterostructure boosted visible light absorption and prevented electron–hole pair recombination. The photodegradation performance of prepared nanoparticles were assessed toward the photodegradation of organic pollutants such as Rhodamine 6 G dye (R6G) as a pollutant model after it has been irradiated by natural solar light. The results of the study indicate a high level of photocatalytic activity specially ZnO/ BiVO4/MWCNT (96.8%) after 120 min, which may be ascribed to its improved charge carrier separation compared to the bare BiVO4 and ZnO NPs. Also, the surface charge of the studied photocatalysts were investigated using IEP measurements and revealed a beneficial role in the separation and regeneration of the photocatalysts. Finally, the proposed photodegradation mechanism was investigated by studying the band structure.