Defect mediated visible light induced photocatalytic activity of CoO nanoparticle decorated MoS nanoflower: A combined experimental and theoretical study.

In this work, CoO nanoparticle-decorated MoS (MoS@CoO) hetero-nanoflowers were synthesized by a facile hydrothermal method, and the effect of CoO on the morphological, structural, optical, electronic, and photocatalytic properties of MoS was analyzed. The surface morphology of MoS and MoS@CoO was studied via field emission electron microscopy (FE-SEM) and transmission electron microscopy (TEM), which revealed a strong interaction between the MoS nanoflower and the nanoparticles. The X-ray diffraction pattern showed a decrease in the crystallite sizes from 7.35 nm to 6.26 nm due to the incorporation of CoO. The UV-Vis spectroscopy of the analysis revealed that the indirect band gap of MoS was reduced from 1.89 eV to 1.65 eV with the incorporation of CoO nanoparticles. Density functional theory (DFT) calculations were used to investigate the electronic properties of MoS and MoS@CoO hetero-nanoflowers, which also showed a reduction in the electronic band gap for the CoO nanoparticles that were injected. The presence of defect states was also observed in the electronic property of MoS@CoO. The photocatalytic activity of the prepared composite and nanoflower is studied using an aqueous solution of methylene blue (MB), and the efficiencies are found to be 27.96% for MoS and 78.89% for MoS@CoO. The improved photocatalytic efficiency of MoS@CoO hetero-nanoflower can be attributed to narrowing the band gap together with the creation of defect states by the injection of nanoparticles that slows down electron-hole recombination rate by trapping charge carrier. The degradation analysis of the composite provides a new route for the purification of polluted water.