Defect mediated visible light induced photocatalytic activity of Co₃O₄ nanoparticle decorated MoS₂ nanoflower: A...

In this work, Co₃O₄ nanoparticle-decorated MoS₂ (MoS₂@Co₃O₄) hetero-nanoflowers were synthesized by a facile hydrothermal method, and the effect of Co₃O₄ on the morphological, structural, optical, electronic, and photocatalytic properties of MoS₂ was analyzed. The surface morphology of MoS₂ and MoS₂@Co₃O₄ was studied via field emission electron microscopy (FE-SEM) and transmission electron microscopy (TEM), which revealed a strong interaction between the MoS₂ 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 Co₃O₄. The UV-Vis spectroscopy of the analysis revealed that the indirect band gap of MoS₂ was reduced from 1.89 eV to 1.65 eV with the incorporation of Co₃O₄ nanoparticles. Density functional theory (DFT) calculations were used to investigate the electronic properties of MoS₂ and MoS₂@Co₃O₄ hetero-nanoflowers, which also showed a reduction in the electronic band gap for the Co₃O₄ nanoparticles that were injected. The presence of defect states was also observed in the electronic property of MoS₂@Co₃O₄. 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 MoS₂ and 78.89% for MoS₂@Co₃O₄. The improved photocatalytic efficiency of MoS₂@Co₃O₄ 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.