PEGylated MoS2 Nanosheets: A Dual Functional Photocatalyst for Photodegradation of Organic Dyes and Photoreduction of Chromium from Aqueous Solution

Abstract

This article reports the synthesis of PEGylated microspheres of MoS2 nanosheets through the hydrothermal method and its application in rhodamine B and methylene blue dyes photodegradation, and photoreduction of chromium(VI) to chromium(III) in water under illumination with visible light. The catalyst was characterized using X-ray Diffraction (XRD), Transmission Electron Microscopy (TEM), Field Emission Scanning Electron Microscopy (FESEM), Energy Dispersive X-ray Spectroscopy (EDS), Fourier Transform Infra Red (FTIR), Thermo-gravimetric Analysis (TGA), and UV-Vis spectroscopies. XRD result reveals the MoS2 nanosheets to be present in the hexagonal phase of MoS2. SEM, TEM, and HRTEM images show that the synthesised sample has spherical shapes made up of several thin sheets of MoS2. The catalyst showed visible light responsivity with a calculated band gap of 1.92 eV. The MoS2 nanosheets exhibited high degradation efficiency against both dyes. The RhB and MB dyes experienced degradation efficiencies of 97.30 % (RhB) and 98.05 % (MB) in 75 min 90 min, respectively. The MoS2 photocatalyst is also observed to be effective in photocatalytic reduction of Cr(VI) and displayed 91.05% reduction of Cr(VI) to Cr(III) in 75 min. The results reveal that the synthesised MoS2 nanosheet is a good photocatalytic material for degradation of dyes and reduction of Cr(VI) to Cr(III) in water.

MoS2 Nanosheet/ZnS Composites for the Visible-Light-Assisted Photocatalytic Degradation of Oxytetracycline

“…Fortunately, the preparation of ZnS composites with narrow band gap semiconductor nanomaterials is an effective and widely used method to extend visible light absorption and improve the photocatalytic efficiency. Noble metal-free MoS 2 -based nanocomposites have also emerged as efficient photocatalysts having broad photocatalytic applications, such as energy generation and water treatment, owing to their large surface area, narrow band gap, low cost, visible light response, and complex edges having a highly unsaturated nature. − However, the small band gap of single-layer MoS 2 (approximately 1.9 eV) limits its photocatalytic efficiency owing to the rapid recombination of charge carriers. Several attempts have been made to delay the recombination of charge carriers, such as the fabrication of MoS 2 nanosheets with wide-band-gap semiconductor nanomaterials (e.g., TiO 2 , Bi 2 O 3 , CdS, and ZnS) in order to enhance their potential for the degradation of organic water contaminants. ,,− Thus, ZnS/MoS 2 heterostructure nanocomposite materials have been studied as photocatalysts with improved photocatalytic potential compared to pure nanosized MoS 2 and ZnS. ,− For example, Jeon et al prepared ZnS loaded with MoS 2 nanoflakes and observed that the photocatalytic performance of the ZnS/MoS 2 nanocomposite was enhanced compared to those of pristine ZnS and MoS 2 because of the enhanced surface area.…”

Unusual nanoscale piezoelectricity-driven high current generation from a self S-defect-neutralised few-layered MoS2 nanosheet-based flexible nanogenerator

“…6b). 48,49 The characteristic peak of the MoS 2 nanosheets at 455 cm −1 is also observed. The peaks observed at 809 and 1079 cm −1 are due to the stretching and bending of Si–O–Si bonds in the PDMS matrix, respectively.…”

Multifunctional Hybrid MoS2-PEGylated/Au Nanostructures with Potential Theranostic Applications in Biomedicine

“…The band at 659.3 cm −1 is also derived from the C-C vibration of the PEG skeleton, as well as the intense band at 817.2 cm −1 [42,44,45]. The band at 992.7 cm −1 refers to the stretching and bending mode of the O-H bonds and the stretching of the C-C bonds, which is well defined and more intense for primary alcohols, as is the case with PEG [34,[46][47][48][49]. The MoS2-PEG/Au hybrid presented the same bands as the MoS2-PEG, but with the additional band at 1493.0 cm −1 ascribed to γ(C-C) from PEG which was intensified due the presence of gold nanostructures [50].…”