Characterization and antibacterial capabilities of nanocrystalline CdS thin films prepared by chemical bath deposition

Facile Synthesis of Barium-Doped Cadmium Sulfide Quantum Dots for the Treatment of Polluted Water: Experimental and Computational Investigations

In this study, cadmium sulfide (CdS) quantum dots (QDs) and barium (Ba) (3 and 6 wt %)-doped CdS QDs were synthesized via a hydrothermal technique. The basic purpose of this work is to degrade methylene blue (MB) dye and evaluate density functional theory (DFT). The synthesized samples were characterized through X-ray powder diffraction (XRD), selected area electron diffraction (SAED), Fourier transform infrared spectroscopy (FTIR), scanning electron microscope (SEM), high-resolution transmission electron microscopy (HR-TEM), UV-vis spectrophotometer, PL, and density functional theory (DFT). The XRD (structural analysis) confirmed that the hexagonal crystal structure and crystallinity increased upon doping. Selected area electron diffraction (SAED) analysis confirmed the polycrystalline nature of the prepared QDs. The functional groups have been investigated using FTIR analysis. The surface and structural morphologies of the synthesized specimen have been investigated by applying TEM and FE-SEM, and it was found to exhibit the topology of QDs. In addition, optical characteristics have been investigated via UV-vis absorption spectroscopy, which exhibited a bathochromic shift (red shift) as a consequence of the reduction of the band-gap energy upon doping from 2.56 to 2.38 eV. PL analysis was used to observe the electron-hole recombination rate. Moreover, the electronic and optical properties of Ba-doped CdS were further explored using density functional theory. Pristine and Ba-doped QDs exhibit sufficient catalytic activity (CA) against the MB dye in all media as 62.59, 70.15, and 72.74% in neutral, basic, and acidic solutions, respectively.

Surface lattice resonance of line array of poly (glycidyl methacrylate) with CdS quantum dots for label-free biosensing

One dimensional plasmonic grating is a kind of resonant electromagnetic wave absorber with a characteristic wavelength. This study focusses on one-dimensional plasmonic grating consisting of poly (glycidyl methacrylate) (PGMA) brushes and CdS quantum dots (CdQDs) fabrication and PGMA chains grafted on a primary substrate in a line array continued by the immobilization of biotin-modified CdQDs. PGMA brush line array (PBLA) of plasmonic grating exhibited an absorptance at 441 nm while at the same time, CdQDs immobilized with PBLA showed characteristic absorbance at 396 nm. The blue-shift from 441 nm matches the absorbance peak of biotin-modified CdQDs resulting in the enhancement of photoluminescence emission of CdQDs. With streptavidin incubation to assemble CdQDs at 50 nM, the significant decrease in grating height resulted in the red-shift of the absorbance peak to 536 nm. Due to the deviation in absorbance, the intensity of the PL emission decreased gradually with the increase in concentration of streptavidin. In addition, our results showed that streptavidin incubation altered the color reflected from the surface due to effective changes in the refractive index of the layer as well. The limit of detection of the grating for streptavidin detection was determined to be 50 nM. Thus, PBLA-CdQD has the potential to act as a highly-sensitive, label-free optical biosensor.