Abstract

Molybdenum disulfide (MoS₂) composed of layer structure attracts much attention as a semiconductor material, whose band gap energy is changed from 1.29 eV as an indirect transition to 1.85 eV as a direct one, by changing the number of layers. Here, we show the exfoliation of MoS₂ using sonication in a mixed solvent (H₂O and ethanol). The results of Raman spectra and atomic force microscope and transmission electron microscope images reveal that the exfoliated MoS₂ is composed of a few layers. Photocatalysis of the prepared MoS₂ was investigated by the degradation of a dye solution of methyl orange (MO) by irradiating light at the wavelength of 450 nm. As a result, the dye solution became colorless under the existence of the layered MoS₂ as a function of irradiation time. Note that the absorption band of MO disappears at around 460 nm, whereas a new band emerges at around 240 nm. This new band is considered as a hydrazine molecule, which can be produced from the photocatalytic reaction via the decomposition of MO.

© 2017 Japan Society of Applied Physics, Optical Society of America