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Carbon quantum dots implanted CdS nanosheets: Efficient visible-light-driven photocatalytic reduction of Cr(VI) under saline conditions
摘要： Chromium(VI) (Cr(VI)), a toxic metal, is generally present together with ionic salts in industrial effluents. An efficient reduction of Cr(VI) to Cr(III) in saline water is an imperative issue but still a challenging task. Literature has rarely addressed reducing Cr(VI) effectively under saline conditions. Herein, carbon quantum dots (CQDs) were successfully implanted in the CdS nanosheets (CdS-NSs) to prepare nanocomposites (i.e., CCNs) for the first time to efficiently reduce Cr(VI) to Cr(III). The newly fabricated CCNs demonstrated superior performance to reduce Cr(VI) compared to pristine CdS-NSs and CQDs-deposited CdS nanosheets (i.e., CQD/CdS-NSs) in saline water. The nanostructures were examined by spectral and photoelectrochemical measurements as well as density functional theory (DFT) calculations. Results showed that CCNs facilitated the photo-electron transport and thus suppressed charge recombination via formation of micro-regional heterostructures. A lower band gap of CCNs relative to pristine CdS-NSs and CQD/CdS-NSs extended the light absorption spectrum. The optimal photocatalyst, denoted as CCNs-2, exhibited an efficiency of ~94% for photocatalytic Cr(VI) reduction within 10 min in water containing 1200 mg/L salts. The obtained rate constant of reduction of Cr(VI) was (2.62 ± 0.04) × 10-1 min-1, approximately 4 and 3 times higher than that of pristine CdS-NSs and CQD/CdS-NSs, respectively. After 3 cycles, the CCNs-2 still showed an efficiency of ~78% aqueous Cr(VI) reduction within 10 min. Our results clearly presented that implantation relative to deposition of CQDs for CdS-NSs is a preferential strategy to enhance photocatalytic Cr(VI) reduction in saline water under visible light irradiation.
关键词： Saline water,Implantation,Photocatalytic Cr(VI) reduction,Carbon quantum dots,Cadmium sulfide nanosheets
更新于2025-09-19 17:13:59
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Performance of Graphenea??CdS Hybrid Nanocomposite Thin Film for Applications in Cu(In,Ga)Se2 Solar Cell and H2 Production
摘要： A graphene–cadmium sulfide (Gr–CdS) nanocomposite was prepared by a chemical solution method, and its material properties were characterized by several analysis techniques. The synthesized pure CdS nanoparticles (NPs) and Gr–CdS nanocomposites were confirmed to have a stoichiometric atomic ratio (Cd/S = 1:1). The Cd 3d and S 2p peaks of the Gr–CdS nanocomposite appeared at lower binding energies compared to those of the pure CdS NPs according to X‐ray photoelectron spectroscopy analyses. The formation of the Gr–CdS nanocomposite was also evidenced by the structural analysis using Raman spectroscopy and X‐ray diffraction. Transmission electron microscopy confirmed that CdS NPs were uniformly distributed on the graphene sheets. The absorption spectra of both the Gr–CdS nanocomposite and pure CdS NPs thin films showed an absorption edge at 550 nm related to the energy band gap of CdS (~2.42 eV). The Cu(In,Ga)Se2 thin film photovoltaic device with Gr–CdS nanocomposite buffer layer showed a higher electrical conversion efficiency than that with pure CdS NPs thin film buffer layer. In addition, the water splitting efficiency of the Gr–CdS nanocomposite was almost three times higher than that of pure CdS NPs.
关键词： cadmium sulfide,Gr–CdS,Cu(In, Ga)Se2,buffer layer,water splitting
更新于2025-09-19 17:13:59
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The Application of Self-Assembled of Meso-2,3-Dimercaptosuccinic Acid-Polydopamine-Zinc Oxide for Trace Cadmium Analysis
摘要： Nanomaterials have been applied in the analysis of trace contaminants in aquatic samples; however, the adsorption affinity of heavy metal ions to metallic oxide nanoparticles is low. Meso-2,3-dimercaptosuccinic acid-polydopamine-zinc oxide (DMSA/PDA/ZnO) was synthesized through a facile self-assembly process for enhancing the adsorption capacity of ZnO to cadmium cation (Cd(II)). A method for the analysis of trace Cd(II) in water samples was developed while using dimercaptosuccinic acid/Polydopamine/zinc oxide (DMSA/PDA/ZnO) as an adsorbent and atomic absorption spectrometry (AAS) as a means of determination. The results demonstrate that the adsorption ratio of DMSA-PDA-ZnO to 1 mg/L Cd(II) is around 95% at pH 6.0–8.0 with a contact time of 31 h, and the enrichment rate can be more than 98% with the dosage of DMSA-PDA-ZnO exceeding 1.0 g/L. The adsorption isotherm of Cd(II) to DMSA/PDA/ZnO fits the Langmuir equation well, and the saturated adsorption of DMSA-PDA-ZnO to Cd(II) is 28.5 mg/g. The detection limit (3σ) of this method is 0.1 μg/L, with a relative standard deviation of 1%. Additionally, this method presents satisfactory performance with a recovery rate of 86?90% when applied to the detection of Cd(II) in environmental water samples.
关键词： polydopamine,ZnO,cadmium,dimercaptosuccinic acid
更新于2025-09-19 17:13:59
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An Electrically Controlled Wavelength-Tunable Nanoribbon Laser
摘要： Nanoscale laser sources with downscaled device footprint, high energy efficiency and operation speed are pivotal for a wide array of opto-electronic and nanophotonic applications ranging from on-chip interconnects, nano-spectroscopy, sensing to optical communication. The capability of on-demand lasing output with reversible and continuous wavelength tunability over broad spectral range enables key functionalities in wavelength-division multiplexing (WDM) and finely controlled light-matter interaction, which remains an important subject under intense research. In this study, we demonstrate an electrically controlled wavelength-tunable laser based on CdS nanoribbon (NR) structure. Typical ‘S’-shaped characteristics of pump power dependence was observed for dominant lasing lines, with concomitant line width narrowing. By applying an increased bias voltage across the NR device, the lasing resonance exhibits a continuous tuning from 510 nm to 520 nm for a bias field ranged within 0 kV/cm – 15.4 kV/cm. Systematic bias-dependent absorption and time-resolved photoluminescence (PL) measurements were performed, revealing a red-shifted band edge of gain medium and prolonged PL lifetime with increased electric field over the device. Both current-induced thermal reduction of band gap and Franz-Keldysh effect were identified to account for the modification of lasing profile, with the former factor playing the leading role. Furthermore, dynamical switching of NR lasing was successfully demonstrated, yielding a modulation ratio up to ~ 21 dB. The electrically tuned wavelength-reversible CdS NR laser in this work, therefore, presents an important step towards color-selective coherent emitters for future chip-based nano-photonic and opto-electronic circuitry.
关键词： cadmium sulfide,individual nanoribbon,nanolaser,wavelength-tunable,electrical control
更新于2025-09-19 17:13:59
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Nonradiative Energy Transfer in a??Colloidal Quantum Dot Nanoclustera??Dyea?? Hybrid Nanostructures: Computer Experiment
摘要： A computer model of nonradiative electronic excitation energy transfer from nanoclusters of colloidal quantum dots of cadmium selenide to the meso-tetra(3-pyridyl)porphyrin molecule in hybrid nanostructures nanocluster–dye has been constructed and analyzed. The model uses the experimental luminescence and absorption spectra of quantum dots and the dye, takes into account heterogeneity of the properties of quantum dots in nanoclusters and the different location of the dye in the hybrid structure. It has been shown that, in the ideal case, due to such energy transfer, the intensity of the luminescent signal of the dye can be increased by five orders of magnitude. However, this value is significantly reduced due to nonluminescent particles, the presence of a protective ligand shell, a large size distribution of the particles, and the non-optimal geometric structure of the hybrid system.
关键词： porphyrin dye,colloidal quantum dots,F?rster resonance energy transfer,hybrid systems,cadmium selenide,computer simulation
更新于2025-09-19 17:13:59
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A Complex for Diagnostics of Laser Radiation of Semiconductor Targets Excited by a High-Frequency-Modulated Electron Beam
摘要： A complex of equipment for diagnosing the parameters of laser radiation of semiconductor targets, which are excited by high-frequency-modulated electron-beam pulses, is described. The ability to control the shape and duration of laser radiation in the picosecond range via high-frequency modulation of an accelerating-voltage pulse was demonstrated experimentally. A train of laser-radiation pulses with a maximum intensity of up to 2 × 107 W/cm2 was obtained on a cadmium sulfide target (λ = 525 nm).
关键词： picosecond range,cadmium sulfide,semiconductor targets,high-frequency-modulated electron-beam pulses,laser radiation
更新于2025-09-16 10:30:52
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X-ray total scattering study of magic-size clusters and quantum dots of cadmium sulphide
摘要： Four types of magic-size CdS clusters and three different CdS quantum dots have been studied using the technique of X-ray total scattering and pair distribution function analysis. We found that the CdS quantum dots could be modelled as a mixed phase of atomic structures based on the two bulk crystalline phases, which is interpreted as representing the effects of random stacking of layers. However, the results for the magic-size clusters are significantly different. On one hand, the short-range features in the pair distribution function reflect the bulk, indicating that these structures are based on the same tetrahedral coordination found in the bulk phases (and therefore excluding new types of structures such as cage-like arrangements of atoms). But on the other hand, the longer-range atomic structure clearly does not reflect the layer structures found in the bulk and the quantum dots. We compare the effect of two ligands, phenylacetic acid and oleic acid, showing that in one case the ligand has little effect on the atomic structure of the magic-size nanocluster, and in another it has a significant effect.
关键词： magic-size clusters,pair distribution function analysis,X-ray total scattering,quantum dots,cadmium sulphide
更新于2025-09-16 10:30:52
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Distarch Phosphate as a Matrix for the Generation of Quantum Dots
摘要： Generation of ZnS, CdS, CaS and MgS quantum dots (QDs) was attempted in the matrix of distarch phosphate, an anionic polysaccharide. Based on the analysis of FTIR spectra, thermograms and Differential Scanning Calorimetry, interactions of QDS with the matrix could be excluded. On generation of MgS QDs and also, to a certain extent, CaS QDs, hydrolysis of the salts generating these QDs took place. That process had an impact on the partial destruction of the matrix. Molecular weight and radii of gyration of the products showed that the generation of QDs was dependent on the properties of the matrix polysaccharide. The elasticity, plasticity and viscosity of the gels containing QDs were significantly lower than those of plain distarch phosphate. Generally these values changed with time similarly to gels free of QDs.
关键词： Biocomposites,Calcium sulfide,Cadmium sulfide,Magnesium sulfide,Zinc sulfide,Luminescent biodegradable foils
更新于2025-09-16 10:30:52
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Enhancing electron diffusion length in narrow-bandgap perovskites for efficient monolithic perovskite tandem solar cells
摘要： Developing multijunction perovskite solar cells (PSCs) is an attractive route to boost PSC efficiencies to above the single-junction Shockley-Queisser limit. However, commonly used tin-based narrow-bandgap perovskites have shorter carrier diffusion lengths and lower absorption coefficient than lead-based perovskites, limiting the efficiency of perovskite-perovskite tandem solar cells. In this work, we discover that the charge collection efficiency in tin-based PSCs is limited by a short diffusion length of electrons. Adding 0.03 molar percent of cadmium ions into tin-perovskite precursors reduce the background free hole concentration and electron trap density, yielding a long electron diffusion length of 2.72 ± 0.15 μm. It increases the optimized thickness of narrow-bandgap perovskite films to 1000 nm, yielding exceptional stabilized efficiencies of 20.2 and 22.7% for single junction narrow-bandgap PSCs and monolithic perovskite-perovskite tandem cells, respectively. This work provides a promising method to enhance the optoelectronic properties of narrow-bandgap perovskites and unleash the potential of perovskite-perovskite tandem solar cells.
关键词： narrow-bandgap perovskites,perovskite solar cells,tandem solar cells,electron diffusion length,cadmium ions
更新于2025-09-16 10:30:52
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Effect of diode laser on physical properties of CdS thin films
摘要： In this study, Cadmium Sulphide (CdS) thin films are deposited on glass substrates by means of Spray Pyrolysis method to examine the influence of electromagnetic and optical features of these films by diode laser. Accordingly, samples are feasibly irradiated by laser pointer with a power of 500 mw and a wavelength of 532 nm at distance of 10 cm from the source during dissimilar exposure times of 10,20,30,40,50,60,70 and 80 minutes. The absorbance spectrums have been measured by UV-visible spectrophotometer under range of 190-1100 nm .Optical parameters such as transmission , reflection ,absorption coefficient (α), extinction coefficient (K), optical band gap (Eg), refractive index (n), and complex dielectric constants were evaluated from absorbance spectra. The results shows that the laser pointer irradiation cause decreased in transmittance (T), reflectance (R), absorption coefficient α, the extinction coefficient (K), refractive index (n) and the real and imaginary parts of dielectric constant and decrease in the value of the energy gap (Eg). In study of FTIR-spectrum of CdS films in different ratio of irradiation times, there was no change in the peak positions just bigger or smaller with increase in times of irradiation.
关键词： Cadmium Sulfide (CdS),Laser Irradiation,Electromagnetic and Optical Properties,Spray Pyrolysis,Thin Film
更新于2025-09-16 10:30:52