Defect mediated visible light induced photocatalytic activity of Co(3)O(4) nanoparticle decorated MoS(2) nanoflower: A combined experimental and theoretical study

In this work, Co(3)O(4) nanoparticle-decorated MoS(2) (MoS(2)@Co(3)O(4)) hetero-nanoflowers were synthesized by a facile hydrothermal method, and the effect of Co(3)O(4) on the morphological, structural, optical, electronic, and photocatalytic properties of MoS(2) was analyzed. The surface morphology of MoS(2) and MoS(2)@Co(3)O(4) was studied via field emission electron microscopy (FE-SEM) and transmission electron microscopy (TEM), which revealed a strong interaction between the MoS(2) 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 Co(3)O(4). The UV–Vis spectroscopy of the analysis revealed that the indirect band gap of MoS(2) was reduced from 1.89 eV to 1.65 eV with the incorporation of Co(3)O(4) nanoparticles. Density functional theory (DFT) calculations were used to investigate the electronic properties of MoS(2) and MoS(2)@Co(3)O(4) hetero-nanoflowers, which also showed a reduction in the electronic band gap for the Co(3)O(4) nanoparticles that were injected. The presence of defect states was also observed in the electronic property of MoS(2)@Co(3)O(4). 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(2) and 78.89% for MoS(2)@Co(3)O(4). The improved photocatalytic efficiency of MoS(2)@Co(3)O(4) 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.