Anomalous lattice vibrations and smaller bandgap heterostructure of hydrothermally synthesized γ-Fe2O3@Au/MoS2 nanoflakes for photocatalytic degradation of methyl blue under visible light.

Pradeep Kumar^1*, Utkarsh Kumar¹, Yu-Ching Huang², Po-Yo Tsai¹, Chia-Hao Liu³, Chiu-Hsien Wu^1,3, Wen-Min Huang¹, Kuen-Lin Chen^1,3

¹Department of Physics, National Chung Hsing University, Taichung, Taiwan, Taichung, Taiwan
²Department of Materials Engineering, Ming Chi University of Technology, Taishan Distric, Taiwan
³Institute of Nanoscience,, National Chung Hsing University, Taichung, Taiwan

* Presenter:Pradeep Kumar, email:pksingh0021@gmail.com

The composition of MoS2 and γ-Fe2O3@Au heterostructures with a broad spectrum of UV-light absorbance was synthesized via hydrothermal methods. The bandgap of the heterostructure was estimated from the Tauc plot and reported to be 1.61 eV (indirect) and 2.23 eV (direct). In the Raman spectra E_2g^1, A1g, 2LA were the major c-axis and plane modes with a good enhancement that made it optically and electrically active. A1g has higher intensity compared to E_2g^1 due to the exciting d_z^2 state. Marvelous morphology and topology of MoS2 nanoflakes with γ-Fe2O3@Au core-shells were identified. New exciting stages 3p, 3s, and 4p of Mo were found, which creates new ideas for different applications. Photocatalyst properties were studied to degrade Methyle Blue (MB) dye in visible light (8 watts) at different concentrations of catalysis and PH values under room temperature. The (K_app) pseudo-first-order reaction rate constant (min-1) has linear behaviour with a concentration of catalysis and different PH, showing that catalysis was not reacted with MB. Fastly degradation MB at large PH, more than 98 % efficiency was calculated within a few hours. Density functional techniques (DFT/B3LYP) techniques were used to calculate the energies, geometric structure, and vibrational numbers of MoS2 and γ-Fe2O3@Au using LANL2MB basis set. The FTIR and FT-Raman spectra were measured. The basic vibrational wavenumbers and intensities were computed and good agreement was found between the experimental and theoretical vibrational spectrum.

Keywords: Hydrothermal, Anomalous vibration, Methyle blue, Photocatalyst, DFT