One-step hydrothermal synthesis of 2H-MoS2 nanoflowers for efficient degradation of methylene blue and rhodamine B dyes under UV and visible-light irradiation: A comparative study

Abstract

Molybdenum disulfide (MoS2), with its low energy bandgap, plays an essential role in removing organic pollutants from wastewater via the mechanism of photocatalysis. In this paper, the 2H phase of MoS2 nanoflowers (NFs) as a photocatalyst was synthesized by the facial one-step hydrothermal method. Various characterization techniques, such as X-ray diffraction (XRD), field-emission scanning electron microscopy (FE-SEM), Fourier transform infrared spectroscopy (FT-IR), energy dispersive X-ray spectroscopy (EDX), and UV-visible spectroscopy, were carried out to investigate the structural, morphological, chemical compositional, and optical properties of MoS2 NFs. The obtained MoS2 NFs have excellent crystallinity with an average grain size of 6.84 nm. While the calculated optical bandgap (Eg) of the MoS2 NFs was determined to be 1.82 eV. The photocatalytic activity of the as-prepared MoS2 NFs has been demonstrated by degrading both rhodamine B (RhB) and methylene blue (MB) dyes under UV and visible light irradiation. The results reflected that in the case of using the UV source, the photocatalytic degradation speed of the MB dye is very close to that of the RhB dye, while the degradation of the RhB dye is still faster and more efficient, especially in the first 20 minutes of the irradiation period. However, in the case of using visible light, the MB dye degraded faster and more efficiently than the RhB dye. In addition, the photocatalytic mechanism has been explained, and MoS2 NFs have shown excellent reusability.