The thin film of N-doped ZnO/CNT nanocomposite was successfully fabricated on soda lime glass substrate by a simple sol-gel drop-coating method. The structural, morphological, chemical, and optical properties of as prepared samples were characterized by a variety of tools such as X-ray Diffraction (XRD), Field Emission Scanning Electron Microscopy (FE-SEM), Fourier Transform Infrared spectroscopy (FT-IR), and UV-visible spectroscopy. The hexagonal crystalline structure was confirmed from XRD measurement without any other impurity phase detection in samples. The N-doped ZnO/CNT composite showed excellent photo-catalytic activity towards cationic methylene blue (MB) dye degradation with 100% removal rate under UV light irradiation as compared to N-doped ZnO (65%) and pure ZnO (47.36%). The convincing performance has also been observed for the case of visible light irradiation. The enhancement of that photocatalytic activity might be due to narrowing the band gap as well as the reduction of electron–hole pair recombination in ZnO matrix with the incorporation of dopant nitrogen and CNT. It is assumed from the obtained results that N-doped ZnO/CNT nanocomposite thin film can be employed as an economically achievable and ecofriendly method to degrade dye with UV and visible light irradiation. Additionally, density functional theory (DFT) calculations were applied to explore the effect of N-doping on electronic structure of ZnO. The computational study has supported the experimental results of significant band gap contraction, which leads to the maximum absorption towards higher wavelength and no appreciable change of lattice parameters after doping. A conceivable photocatalytic mechanism of N-doped ZnO/CNT nanocomposite has been proposed as well.

Here, we prepared two kinds of nanocomposites (MCT#1 and MCT#2) involving MWCNTs and TiO₂ nanoparticles. The characterisation of the samples is carried out based on FTIR spectroscopy and TEM. The Ti-O groups that is attributed to the TiO₂ nanoparticles can be confirmed according to the FTIR analysis. TEM images show that the average particle size of TiO₂ nanoparticles in prepare MCT#1 and MCT#2 is equal to 13 nm and 15 nm, respectively. The influences of nanocomposites weight fraction and illumination time are investigated on the decomposition rate of methyl orange (MO) as pollutant. The photocatalytic results exhibit that the decomposition rate of MO is increased with respect to the weight fraction and illumination time. Meanwhile, higher decomposition rate can be observed using MCT#2 compared to MCT#1. Statistical analysis of the results based on Duncan’s multiple range test at α = 0.05 reveals that all of the applied levels of the factors have a significant effect on the decomposition rate. The response surface results confirm that the effect of illumination time is high that that of weight fraction of MCT#1 and MCT#2.