Preparation of rGO/MoSe2 nanocomposites for enhanced microwave absorption of whole X and Ku bands.

rGO-MoSe2 nanocomposites were prepared via a one-pot hydrothermal method in which MoSe2 microspheres (MS) were decorated on rGO sheets. Three nanocomposites named F1, F2, and F3 were prepared using different weight ratios of MoSe2 MS to rGO: (3 : 1), (4 : 1), and (5 : 1), respectively. FESEM images showed a flower-like porous morphology of the MoSe2 microspheres. All the rGO-MoSe2 nanocomposites exhibited remarkable microwave absorption properties as demonstrated by strong reflection loss (-58 dB to -99 dB) and an ultrabroad effective absorption bandwidth (equivalent to 90% attenuation), which covers whole X and Ku frequency bands at matching thicknesses of 2.8-3.2 mm. The minimum reflection loss reached -98, -99, and -75 dB for F1, F2 and F3, respectively. The excellent absorption properties of the rGO-MoSe2 nanocomposites is related to the unique morphology and micro size of MoSe2 in which incident waves are attenuated by multiple reflections and scattering.

Efficient Gamma Ray Detection Using CdTe/CdS Core/Shell Quantum Dots: A Simple and Rapid Fluorescence Approach.

Gamma rays, as hazardous nuclear radiation, necessitate effective and rapid detection methods. This paper introduces a low-cost, fast, and simple fluorescence method based on CdTe/CdS core/shell quantum dots for gamma-ray detection. CdTe/CdS quantum dots, subjected to gamma irradiation from a 60Co source under various conditions, were investigated to assess their fluorescence sensor capabilities. The obtained results showed that an increase in CdTe/CdS nanoparticle size was associated with decreased sensitivity, while a reduction in CdTe/CdS concentration correlated with increased sensitivity. To further validate the practicality of CdTe/CdS core/shell quantum dots in gamma-ray detection, the structural properties of the quantum dots were meticulously studied. Raman spectroscopy, X-ray diffraction (XRD), and Fourier-transform infrared (FT-IR) analysis were conducted before and after gamma-ray radiation. The results demonstrated the crystalline stability of CdTe/CdS core/shell quantum dots under gamma irradiation, highlighting their robust structural integrity. In conclusion, the experimental findings underscore the exceptional potential of CdTe/CdS quantum dots as an off-fluorescence probe for simple, low-cost, fast, and on-site detection of gamma rays. This research contributes to the advancement of efficient and practical methods for gamma-ray sensing in various applications.

Application of CdTe/ZnS Core/Shell Quantum Dots as on Fluorescence Sensor for Detection of Gamma Rays.

Gamma rays are a type of ionizing radiation that are extremely hazardous and dangerous for humans and the environment. The fluorescence method is a simple, useful, and fast method for the detection of gamma rays. In this research, CdTe/ZnS core/shell quantum dots were used as on fluorescence sensor for the detection of gamma rays. CdTe/ZnS core/shell QDs were prepared via a simple and rapid photochemical method. The shell thickness and concentration of CdTe/ZnS core/shell quantum dots were studied as two important factors in the optical behavior of CdTe/ZnS quantum dots. The obtained results showed that the PL intensity of CdTe/ZnS QDs after gamma irradiation was increased and also a slight redshift in the PL spectrum was observed. X-ray diffractions (XRD) and Raman analyses were used to study the effect of gamma irradiation on the structural properties of CdTe/ZnS QDs. The obtained results showed that gamma irradiation couldn't damage the crystalline structure of CdTe/ZnS core/shell QDs.

CdS Semiconductor Quantum Dots; Facile Synthesis, Application as Off Fluorescent Sensor for Detection of Lead (Pb2+) Ions and Catalyst for Degradation of Dyes from Water.

The CdS quantum dots (QDs) were prepared by rapid, one-pot, and novel photochemical method, which used Thioglycolic acid (TGA) molecules as both stabilizer and sulfur source. The structure and morphology of the prepared CdS QDs were characterized by different analyses such as XRD, FT-IR, Raman, EDS, TEM, PL, and absorption. In this work, was used of CdS QDs as off fluorescence sensor for rapid and simple detection of lead (Pb2+) ions in water. The PL intensity of CdS QDs in the presence of lead ions decreased gradually and in the presence of 100 µM lead ions, photo emission completely quenched. The photocatalyst performance of CdS QDs was investigated by methylene blue (MB), methylene orange (MO), and rhodamine b (RB) pollutant dyes under both UV and sun lights. The obtained results showed that CdS QDs had excellent photocatalyst activity with dyes under UV light and 94.9% of MO dye, 94.4% of RB dye, and 81.2% of MB was degraded after 60 min UV irradiation. For understanding about which parameter have a key role in the photodegradation process of MO by CdS QDs under UV illumination, several radical scavengers were used, and results showed that holes have a key role in the degradation process.

Mercury (Hg2+) Detection in Aqueous Media, Photocatalyst, and Antibacterial Applications of CdTe/ZnS Quantum Dots.

In the present work, CdTe/ZnS high luminescence quantum dots (QDs) were synthesized by a facile, fast, one-pot, and room temperature photochemical method. Synthesized QDs were characterized by different structural and optical analyses such as X-ray diffraction (XRD), energy dispersive X-ray spectroscopy (EDS), field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), Fourier transform-infrared spectroscopy (FT-IR), Raman, photoluminescence (PL) and UV-visible (UV-vis) spectroscopies. The results confirmed the successful growth of the ZnS shell and formation of CdTe/ZnS core/shell structure. CdTe/ZnS prepared QDs indicated a PL quantum yield of about 51%. These high luminescence QDs were used for detection of Hg2+ ions in aqueous media, as catalyst for photodegradation of different organic dyes, and as antibacterial material for the inhibition of bacterial growth. PL intensity of the CdTe/ZnS QDs was completely quenched after addition of 1 m molar Hg2+in to the media. Photocatalyst activity of CdTe/ZnS QDs was studied by rhodamine b, methylene blue, and methylene orange as organic dyes under both the sun and UV illuminations, and results showed that CdTe/ZnS QDs had the best photocatalyst activity for methylene blue degradation under UV irradiation and radical scavenger results indicated that electrons have a main role in photodegradation of methylene blue dye by CdTe/ZnS QDs under UV illumination. Antibacterial effects of CdTe/ZnS QDs evaluated by Minimum Inhibitory Concentration (MIC), and Minimum Bactericidal Concentration (MBC) methods against two strains of bacteria. The results of the antibacterial test showed that CdTe/ZnS could inhibit bacterial growth in Bacillus cereus (Gram-positive) and Escherichia coli (Gram-negative G) bacteria.

Effect of concentration and shell thickness on the optical behavior of aqueous CdTe/ZnSe core/shell quantum dots (QDs) exposed to ionizing radiation.

In this work CdTe/ZnSe core/shell quantum dots (QDs) were synthesized via a simple, rapid and room temperature photochemical approach. Optical properties of aqueous prepared CdTe/ZnSe QDs were studied systematically under gamma irradiation with dose range of 0 Gy to 20 kGy. The obtained results showed a regular red shift behavior versus gamma irradiation dose, in photoluminescence peak and absorption edge of the CdTe/ZnSe QDs. Structural properties of CdTe/ZnSe QDs before and after gamma irradiation were characterized by means of X-ray diffraction (XRD), Raman and Fourier-transform infrared (FT-IR) analyses. The obtained results showed that the crystalline structure of CdTe/ZnSe core/shell QDs did not change after gamma irradiation. Concentration and shell thickness as two important factors on the sensitivity of CdTe/ZnSe QDs in front of gamma irradiation have been investigated. Based on this study, CdTe/ZnSe QDs are suggested as good candidates for gamma dosimeter.