Narrow Results

Well-defined CdS branched nanorod arrays on ITO glass were fabricated via a facile one-step hydrothermal approach in large scale employing cadmium sulfide and thiourea as starting agents. Structural and morphological evolutions of CdS branched nanorod arrays were studied by scanning electron microscopy, transmission electron microscopy and X-ray diffraction. A formation mechanism of the hierarchical structure via this one-step synthesis was tentatively studied by investigating the reaction time. Tree-like nanostructures can also be obtained at relative higher reaction temperatures. As CdS can directly grow on transparent conductive substrate, the product obtained here should have potential applications in optoelectric devices such as solar cells and light sources.

Cadmium sulfide (CdS) and aluminum-doped zinc oxide (Al:ZnO) thin films are used as buffer layer and front window layer, respectively, in thin film solar cells. CdS and Al:ZnO thin films were produced using chemical bath deposition (CBD) and sol–gel technique, respectively. For CBD CdS, the effect of bath composition and temperature, dipping time and annealing temperature on film properties was investigated. The CdS films are found to be polycrystalline with metastable cubic crystal structure, dense, crack-free surface morphology and the crystallite size of either few nanometers or 12–17 nm depending on bath composition. In case of CdS films produced with 1:2 ratio of Cd and S precursors, spectrophotometer studies indicate quantum confinement effect, owing to extremely small crystallite size, with an increase in E_g value from 2.42 eV (for bulk CdS) to ~ 3.76 eV along with a shift in the absorption edge toward ~ 330 nm wavelength. The optimum annealing temperature is 400°C beyond which film properties deteriorate through S evaporation and CdO formation. On the other hand, Al:ZnO films prepared via spin coating of precursor sols containing 0.90–1.10 at.% Al show that, with an increase in Al concentration, the average grain size increases from 28 nm to 131 nm with an associated decrease in root-mean-square roughness. The minimum value of electrical resistivity, measured for the films prepared using 0.95 at.% Al in the precursor sol, is ~ 2.7 × 10^-4 Ω ⋅ cm. The electrical resistivity value rises upon further increase in Al doping level due to introduction of lattice defects and Al segregation to the grain boundary area, thus limiting electron transport through it.

Cube-shaped CdS nanoparticles have been successfully prepared by a sonochemical method in an oil-in-water microemulsion. The product was characterized by using techniques including X-ray powder diffraction, high-resolution transmission electron microscopy, energy-dispersive X-ray analysis and UV-visible absorption spectroscopy. This microemulsion system in the presence of high-intensity ultrasound irradiation provides special conditions for the nucleation and growth of the CdS nanoparticles.

Materials such as CdS and CdSe inorganic nanoparticles have photoluminescence. Sodium oleate has been used as effective stabilizers for the synthesis of CdS and CdSe nanoparticles in water by autoclave method. Photoluminescence of CdS and CdSe with particle size of 5–14 nm showed λ_max at 520 nm and 600 nm, respectively, when were excited at 365 nm. These nanoparticles doped into the PVA resulted in the organic/inorganic films (PVA/CdS, CdSe). Photoluminescence, X-ray diffraction and transmission electron microscopy were employed for their characterization.

Cadmium sulfide nanoparticles were synthesized and grown on glass substrates by chemical bath deposition. The method involves the preparation of aqueous solutions containing cadmium chloride (CdCl₂) and thiourea [CS(NH₂)₂] as source materials for cadmium and sulfur components, respectively. Ammonium hydroxide (NH₄OH)–ammonium chloride (NH₄Cl) solution was used as a complexing agent in this study. The hexagonal and cubic crystal structure of as-deposited CdS films, determined by X-ray diffraction (XRD), is shown. The effects of Cd:S ratio variation on the surface morphology and optical properties of CdS films are also reported. The UV-vis transmission spectrum and SEM micrographs indicated that the Cd:S ratio in the aqueous solution had an impact on the band gap as well as the crystallite size and packing density of the CdS particles due to the quantum confinement effect.

Cadmium sulfide nanoparticles have been synthesized by hydrothermal method using cadmium acetate, thiosemicarbazide, and sodium hydroxide as precursors with hexamethylene tetramine as the surfactant. From the X-ray diffraction analysis, it is observed that synthesized CdS nanoparticles show cubic phase. The presence of HMTA in CdS was confirmed by FT-IR analysis. The bandgap value of CdS nanostructure has been estimated by DRS–UV-Visible spectral analysis. The formation of flower-like nanoclusters was observed using scanning electron microscopy (SEM). The application of CdS nanoparticles in photocatalytic degradation was also studied.

Fluorescent semiconductor nanocrystals have been widely used as fluorescent materials in chemical sensors, biotechnology, medical diagnostics, biological imaging and many other fields. Compared to the conventional organic fluorophores, the inorganic quantum dots (QDs) have many advantages, including broad absorption spectra, narrow emission spectra, good photostability and long fluorescent lifetime after excitation. Here, the high quality CdS QDs were synthesized directly from sulfur and CdO using the paraffin liquid as solvent and the oleic acid as the reacting media. The synthesized CdS QDs with a zinc blende (cubic) crystal structure were proved by X-ray diffraction. HRTEM observation revealed that the CdS QDs were uniform and the average grain size was about 4 nm. The optical properties of the CdS QDs were characterized by using photoluminescence (PL) spectrophotometer and Ultraviolet-visible (UV-Vis) absorption spectrophotometer. The formation mechanism of CdS QDs in the paraffin liquid and oleic acid system was proposed.

In the present work, Cadmium sulfide (CdS) and CdS doped with copper (Cu) and iron (Fe) metals thin films were deposited on glass slides using chemical bath deposition technique. 1% content of Cu and Fe were used as dopants. The films were prepared at a reaction temperature of approximately 80^∘C and for an hour as the reaction time without any heat treatment. The pure and doped films were diagnosed and examined by several techniques such as X-ray diffraction (XRD), field emission scanning electron microscope (FESEM) and UV-visible spectrometry to study the effect of the doping and the type of dopant material on the surface, structural and optical properties of CdS films. From the results of XRD can be noticed there is no effect for the dopant on the type of crystal structure except small shifting in the position of main peak after doping. The bandgap energy of the Fe-doped CdS films has been found to be lower than that of the undoped films between 2.62 eV and 2.43 eV.

II–VI Semiconductor nanocrystals (NCs) with tunable visible emission, such as CdS, CdSe and CdTe, were synthesized in aqueous solution using thiols as capping molecules. Hydrazine was found to promote the growth of NCs through a special mechanism. In only a few hours, the synthesis process was completed at room temperature. Under moderate conditions, the capping molecules not only changed the growth rate of NCs simply by varying the concentration, but also altered the spectral properties of NCs. The capping molecules with amino groups were propitious to the growth of CdS NCs, whereas the kinetic growth of CdS NCs was more affected by the surface passivation efficiency of NCs than by steric hindrance in the system. The fastest growth of the CdS NCs was achieved when glutathione was used as a capping molecule, while the emission of CdS and CdSe NCs were shown to remain steady and tunable using the same capping molecule. The growth rate of 3-mercaptopropionic acid-capped CdS and CdSe NCs slowed down significantly, while CdTe NCs were obtained with excellent emission properties when capped with the same molecule. Furthermore, our approach will also be useful for the study of the kinetic growth of NCs in aqueous solution.

A new-type photocatalyst of cadmium sulfide carbon nanotubes (CdS/CNTs) was prepared by the hydrothermal method. This as-prepared CdS/CNTs composite photocatalyst was proved to exhibit an excellent photocatalytic activity for degradation of tetracycline (TC). Specially, the 95%-CdS–5%-CNTs composite photocatalyst played the best degradation rate (81.2%) in 60 min under the visible light irradiation. Moreover, this 95%-CdS–5%-CNTs composite photocatalyst possessed great stability and could be used at least four cycles with almost no loss of photocatalytic efficiency. Furthermore, the as-synthesized CdS/CNTs composite photocatalyst was characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), UV-Vis diffused reflectance spectra (UV-Vis), Raman and thermal gravimetry (TG). In addition, the possible mechanism and kinetics of photodegradation of TC with CdS/CNTs photocatalyst was also discussed.

A unique CdS/Fe₃O₄/rGO composite photocatalyst is successfully synthesized by the microwave method. It displays promising photocatalytic activity towards the photo-degrading of tetracycline (TC) in aqueous solution, the degradation rate of TC is 69% with adding 0.1g CdS/Fe₃O₄/rGO photocatalyst into 20mg/L tetracycline for 2h under visible light irradiation. Furthermore, the mechanism was systematically investigated by active species trapping experiment. It can be known that ${\mathrm{\text{e}}}^{-}\mathrm{\text{was}}$ the major active species in the photodegradation process and the possible process of charge transfer for CdS/Fe₃O₄/rGO was proposed based on the experimental results. The as-prepared samples were carefully evaluated by XRD, TEM, XPS, VSM, PL spectra, Raman spectrometer.

An integrated tandem photoelectrochemical (PEC) cell, composed of a three-dimensional (3D) ZnO/CdS/NiFe layered double hydroxide (LDH) core/shell/hierarchical nanowire arrays (NWAs) photoanode and a $p$-Cu₂O photocathode, was designed for unassisted overall solar water splitting in this study. The optical and photoelectrochemical characteristics of ZnO-based photoanodes and Cu₂O photocathode were investigated. The results show that ZnO/CdS/NiFe LDH nanostructures offer significantly enhanced performances with a photocurrent density reaching 5.8mA$\cdot$cm${}^{-2}$ at 0.9V and an onset potential as early as 0.1V (versus RHE). The enhancement can be attributed to the existence of CdS nanoparticles (NPs) which boosts the light absorption in visible region and enhances charge separation. Moreover, the introduction of NiFe LDH nanoplates, with unique hierarchical mesoporous architecture, promotes electrochemical reactions by providing more active sites as co-catalyst. On the above basis, the ZnO/CdS/NiFe LDH–Cu₂O two-electrode tandem cell system was established. At zero bias, the device shows a photocurrent density of 0.4mA$\cdot$cm${}^{-2}$ along with the corresponding solar-to-hydrogen (STH) conversion efficiency reaching 0.50%. Our results indicate that the tandem PEC cells consisting of metal–oxide–semiconductor photoelectrodes based on Earth-abundant and low-cost materials hold promising application potential for overall solar water splitting.

Semiconductor materials used in the field of photocatalysis have been attracting much attention. Due to the advantages of green, pollution-free and sustainable development of solar energy, it is an ideal strategy to explore excellent semiconductor materials as high light photocatalysts for energy conversion. Herein, Bi₄Ti₃O${}_{12}$/CdS composites were synthetized by coprecipitation method, which CdS particles selectively deposited on Bi₄Ti₃O${}_{12}$ nanosheets. The phase structure and optical properties of the samples were characterized by XRD, SEM, N₂ adsorption–desorption and UV-visible diffuse spectra (UV-DRS). The results showed that the Bi₄Ti₃O${}_{12}$/CdS composites had the highest photocatalytic activity against RhB under visible light, and the degradation rate of RhB was 98.8% after 120min of simulated light, 2.14 times that of pure Bi₄Ti₃O${}_{12}$, and the Bi₄Ti₃O${}_{12}$/CdS-10wt.% composites also showed good stability. UV-DRS demonstrated that the optical absorption range of the composite extends to visible regions, and photocurrent tests also showed that the composite enhances the separation and migration of photoogenic electron–hole pairs, mainly due to the formation of 2D nanosheets/0D particles heterojunctions between the bronzn CdS of the perovskite BTO and hexagonal fibers. Furthermore, free radical assays confirmed that both $\cdot$O${}_2^{-}$, h${}^{+}$ and $\cdot$OH have effects in the degradation of RhB, and thus suggested a possible mechanism for the photodegradation process of the Bi₄Ti₃O${}_{12}$/CdS-10wt.% composite photocatalyst.

Two novel CdS- and Cr-doped CdS nanostructures, including nanoparticles and nanoparticles, were successfully synthesized by solvothermal reaction with hydrazine hydrate (HHA), ethylene glycol (EG), ethylenediamine (EN) and ethanolamine (EA) as mixed solvents in different sulfur and cadmium sources. The structure, morphology and properties of the products were characterized using X-ray powder diffraction (XRD), Scanning electron microscopy (SEM), Energy dispersive spectrometer (EDS) and Vibrating sample magnetometer (VSM), respectively. The morphology of the Cr-doped CdS nanostructures was nanorod, with an average diameter of 70–90nm and lengths of 1–2.5$\mu$m. The product was observed to be composed of S, Cd and Cr by EDS. The VSM tests demonstrated that the Cr-doped CdS nanorods had super strong ferromagnetism at room temperature, while pure CdS nanorods were weak ferromagnetism. The results confirmed that the prepared the Cr-doped CdS nanorods had ferromagnetism at room temperature, and the saturation magnetization $M_s$ was approximately 9.125 (10${}^{-3}$emu/g), the coercivity of $H_c$ was approximately 139.22Oe.

The advancement of technology has resulted in severe issues in the natural environment, notably organic water contamination that poses a significant threat to living organisms. To mitigate such problems, various technological solutions have been developed to treat water pollution. The emergence of photocatalytic semiconductor technology has enabled the utilization of numerous novel semiconductor composites for pollution control due to their high efficacy and eco-friendliness. In this paper, TpTt/CdS composites were produced via a simple two-step process, and the resulting samples were characterized using X-ray diffraction, field emission scanning electron microscopy, Fourier transform infrared, X-ray photoelectron spectroscopy, ultraviolet (UV)–visible and photodegradation experiments using methylene blue to simulate organic pollutants. The experimental findings reveal that the composite structure system enhances the radiation absorption capacity of CdS in the UV range, as well as the adsorption capability of organic pollutants. This introduces a fresh concept for modifying semiconductor composite structures and highlights the considerable potential of CdS in degrading organic contaminants.

In this study, a cladding-modified fiber-optic sensor is reported for NO₂ gas detection. Monitoring the purity of air is the need of the hour, with the growing technologies. Hence, in this work, Ag-doped CdS is coated over the cladding-removed region of 3cm length by Chemical Bath Deposition (CBD) which acts as the gas-sensing medium. Ag–CdS is coated over four fibers each with a different coating duration of 10min, 20min, 30min and 40min. Characterization of Ag–CdS is done by Scanning Electron Microscope (SEM), UV-visible absorption spectroscopy and UV-visible reflectance spectroscopy. The spectral response for different concentrations of NO₂ is studied on the four fibers separately, and it is analyzed and compared. The minimum detection limit is 100ppm and the response time is 10min. Out of the four fibers, Ag–CdS-30 exhibited the best response with a sensitivity of 15.5%. The results are compared with cladding-modified fiber coated with CdS, which was reported previously. The effect of Ag-doping is analyzed.