Defect mediated visible light induced photocatalytic activity of Co3O4 nanoparticle decorated MoS2 nanoflower: A combined experimental and theoretical study
Mizanur Rahaman, Md Hasive Ahmed, Sarker Md Sadman, Muhammad Rakibul Islam
Abstract
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.