Defect mediated visible light induced photocatalytic activity of Co3O4 nanoparticle decorated MoS2 nanoflower: A combined experimental and theoretical study

Abstract

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.

Keywords

• MoS2 nanoflower
• Co3O4 nanoparticle
• Photocatalysis
• Electronic property
• DFT