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A review of the state of research in the development of conductometric gas sensors based on II–VI semiconductors is given. It was shown that II–VI compounds indeed have properties that are necessary for the development of highly efficient gas sensors. In this case, to achieve the required parameters, all approaches developed for metal oxides can be used. At the same time, during a detailed review, it was concluded that sensors based on II–VI compounds have no prospects for appearing on the gas sensor market. The main obstacle is the instability of the surface state, which leads to poor reproducibility of parameters and drift of sensor characteristics during operation. [ABSTRACT FROM AUTHOR]

This article reports on the fabrication and characterization of MgO nanostructured films and the effect of ZnS and CdS on their structural, optical, and electrical properties. The MgO, MgO: ZnS, and MgO: CdS thin films were deposited using a Chemical spray pyrolysis technique onto glass substrates at 673 K. The XRD patterns revealed that the MgO thin films had a preferred (111) orientation with a pure cubic crystalline structure, while the ZnS and CdS layers had a hexagonal structure. The FE-SEM images showed that the MgO films had a nanostructured morphology with an average particle size of ~50 nm. The UV-Vis spectroscopy results showed that the addition of ZnS and CdS layers to the MgO films resulted in a shift in the absorption edge towards the visible region of the electromagnetic spectrum, indicating an improvement in their optical properties. These findings suggest that the MgOZnS and MgOCdS films could have potential applications in optoelectronic devices.

We report the scalable fabrication of CdS/ZnS 1D/2D heterojunctions under ambient air conditions (i.e., room temperature and atmospheric pressure) in which ZnS nanoparticles are anchored on the surface of CdS nanosheets. The as‐formed heterojunctions exhibit a significantly enhanced photocatalytic H2 evolution rate of 14.02 mmol h−1 g−1 when irradiated with visible light, which is ~10 and 85 times higher than those of pristine CdS nanosheets and CdS nanoparticles, respectively, and superior to most of the CdS‐based photocatalysts reported to date. Furthermore, they provide robust photocatalytic performance with demonstratable stability over 58 h, indicating their potential for practical applications. The formation of 1D/2D heterojunctions not only provides improved exposed active sites that respond to illumination but also provides a rapid pathway to generate photogenerated carriers for efficient separation and transfer through the matrix of single‐crystalline CdS nanosheets. In addition, first‐principles simulations demonstrate that the existence of rich Zn vacancies increases the energy level of the ZnS valence band maximum to construct type‐II and Z‐scheme mixed heterojunctions, which plays a critical role in suppressing the recombination of carriers with limited photocorrosion of CdS to enhance photocatalytic behavior. [ABSTRACT FROM AUTHOR]

Nowadays, the study of environmentally friendly ways of producing hydrogen as a green energy source is an increasingly important challenge. One of these potential processes is the heterogeneous photocatalytic splitting of water or other hydrogen sources such as H2S or its alkaline solution. The most common catalysts used for H2 production from Na2S solution are the CdS-ZnS type catalysts, whose efficiency can be further enhanced by Ni-modification. In this work, the surface of Cd0.5Zn0.5S composite was modified with Ni(II) compound for photocatalytic H2 generation. Besides two conventional methods, impregnation was also applied, which is a simple but unconventional modification technique for the CdS-type catalysts. Among the catalysts modified with 1% Ni(II), the impregnation method resulted in the highest activity, for which a quantum efficiency of 15.8% was achieved by using a 415 nm LED and Na2S-Na2SO3 sacrificial solution. This corresponded to an outstanding rate of 170 mmol H2/h/g under the given experimental conditions. The catalysts were characterized by DRS, XRD, TEM, STEM-EDS, and XPS analyses, which confirmed that Ni(II) is mainly present as Ni(OH)2 on the surface of the CdS-ZnS composite. The observations from the illumination experiments indicated that Ni(OH)2 was oxidized during the reaction, and that it therefore played a hole-trapping role. [ABSTRACT FROM AUTHOR]

Abstract We report the scalable fabrication of CdS/ZnS 1D/2D heterojunctions under ambient air conditions (i.e., room temperature and atmospheric pressure) in which ZnS nanoparticles are anchored on the surface of CdS nanosheets. The as‐formed heterojunctions exhibit a significantly enhanced photocatalytic H2 evolution rate of 14.02 mmol h−1 g−1 when irradiated with visible light, which is ~10 and 85 times higher than those of pristine CdS nanosheets and CdS nanoparticles, respectively, and superior to most of the CdS‐based photocatalysts reported to date. Furthermore, they provide robust photocatalytic performance with demonstratable stability over 58 h, indicating their potential for practical applications. The formation of 1D/2D heterojunctions not only provides improved exposed active sites that respond to illumination but also provides a rapid pathway to generate photogenerated carriers for efficient separation and transfer through the matrix of single‐crystalline CdS nanosheets. In addition, first‐principles simulations demonstrate that the existence of rich Zn vacancies increases the energy level of the ZnS valence band maximum to construct type‐II and Z‐scheme mixed heterojunctions, which plays a critical role in suppressing the recombination of carriers with limited photocorrosion of CdS to enhance photocatalytic behavior.

The features of the deviation of the open circuit potential at the semiconductor–electrolyte contact where cadmium and zinc sulfides are used as semiconductor materials are considered. Models of equivalent electrical circuits that explain the observed phenomena are proposed. Some examples of devices designed on the basis of the research results are given. [ABSTRACT FROM AUTHOR]

• CdS/ZnS heterojunctions were fabricated by low-heat solid-state chemical method. • The heterojunctions exhibited superior photocatalytic activities to others. • A possible mechanism was proposed via radical trapping and theoretical calculation. Photocatalytic technology is environmentally-friendly and energy-saving for degradating organic pollutants. Highly efficient and visible light response photocatalysts are vital for the excellent degradation performance. In the work, CdS/ZnS heterojunctions were fabricated via low-heat solid-state chemical method and the photocatalytic activity was systematically studied. When the molar ratio of ZnS to CdS was 9:1, the CdS/ZnS heterojunctions exhibited the highest photocatalytic activities, and 99 % and 58 % of methyl orange were degraded under UV and visible light, respectively. Besides, 91 % and 94 % of rhodamine B and tetracycline were degraded under UV light, respectively. The outstanding photocatalytic performances of CdS/ZnS heterojunctions were attributed to the enhanced light absorption and the fast migration of carriers, which were verified by UV visible diffuse reflection absorption spectrum, surface photocurrent, and fluorescence spectrum. In addition, on the bases of free radical trapping experiment and theoretical calculation, a possible photocatalytic mechanism was put forwards. The study provides a new idea for the design of highly efficient and wide spectral responsive photocatalysts. [Display omitted] [ABSTRACT FROM AUTHOR]

The current study is on the deposition of Zinc Sulfide and Cadmium Sulfide thin films by chemical bath deposition (CBD) technique. The deposited films were annealed at 200 °C and 350 °C in vacuum system. The Structural, Surface morphology, elemental composition and Optic analysis were performed by XRD, SEM, EDX, PL and optical transmission spectra. The XRD confirmed the formation of ZnS and CdS which revealed a broad spectrum in the low 2θ region due to its amorphous behaviour. The average optical transmission spectrum of ZnS lies between 65 % and 80 % and CdS lies between 50 and 60 %. The optical band gap of both the annealed films was decreasing with increase in temperature. The higher optical transmittance observed from emission spectra of PL analysis can contribute better performance and proved that the annealed ZnS and CdS thin films are applicable for photovoltaic applications. • CdS and ZnS nano thin films are prepared by Chemical Bath Deposition. • By increasing the annealing temperature, the optical band gap decreases. • The optical transmittance is higher for the films prepared and confirmed by Photoluminscence spectroscopy. • Both the nanofilms are recommended for photovoltaic applications. • The films are amorphous in nature and confirmed by XRD Spectroscopy. [ABSTRACT FROM AUTHOR]

In recent years, yolk–shell nanocrystals have become the spotlight of research worldwide because of the fascinating structural properties such as a permeable shell, an interior void space, and a movable yolk. Numerous studies have reported various compositions of yolk–shell nanocrystals. Among them, yolk–shell nanocrystals comprising metal yolk and semiconductor shells are particularly interesting because they can be geared to mass transport-related utilizations, for example, photocatalysis. We reported a sequential ion-exchange process to prepare for metal–semiconductor yolk–shell nanocrystals comprising Au yolk associated with various semiconductor shells. The synthetic procedures involved delicate sulfidation on a Au@Cu2O core–shell nanocrystal template, followed by a kinetically controlled cation-exchange reaction that enabled the conversion of the shell composition into various metal sulfides. Four representative yolk–shell nanocrystal samples, including Au@Cu7S4, Au@CdS, Au@ZnS, and Au@Ni3S4, were synthesized for investigation. X-ray photoelectron spectroscopy and photoluminescence spectroscopy were used to explore the electronic interactions and charge-transfer dynamics between the yolk and shell components. Results showed that interfacial charge transfer between the metal yolk and semiconductor shell was significant for the four yolk–shell nanocrystals, leading to pronounced charge-carrier separation that can be utilized to demonstrate a multitude of photocatalysis applications, including environmental purification, hydrogen production, and carbon dioxide reduction. [ABSTRACT FROM AUTHOR]

Hydrothermal and thermolysis techniques were used to create ZnWO 4 and 0.9ZnWO 4 -0.1MS (M = Cd, Zn, Pb) samples. The formed phases in each sample and their structure and microstructure were examined using Raman spectroscopy, Fourier-transform infrared spectroscopy and Rietveld refinement of Synchrotron x-ray diffraction data. The composition and morphology of the formed samples were investigated via scanning electron microscopy and energy-dispersive X-ray spectroscopy (EDS). The average crystallite size remains relatively constant regardless of the different metal chalcogenides. MS/ZnWO 4 samples have two distinct morphologies. The UV diffuse reflectance spectroscopy (UV-DRS) technique is used to investigate the linear and nonlinear optical parameters for different samples. Alloying ZnWO 4 with CdS or PbS affects the photo response region of the sample to include visible light. MS/ZnWO 4 (MS=CdS, ZnS, PbS) samples have optical band gap values of 2.56, 2.43, 2.99 and 3.1 eV, respectively. The CdS/ZnWO 4 and ZnS/ZnWO 4 samples exhibit the highest refractive index and optical dielectric constant values within the visible range. CdS or PbS/ZnWO 4 samples show the highest nonlinear optical parameters values within the visible range. The impact of MS samples on the photoluminescence emission of ZnWO 4 was explored. The CIE chromaticity diagram reveals that MS/ZnWO 4 (M = Zn and Pb) samples display a different degree of blue color while CdS/ZnWO 4 sample reveals green-yellow colors. • Raman spectra analysis confirmed the formation of CdS phase, nonexistence of the ZnS phase and could not detect PbS phase. • The values of n and k are influenced by the measured range of wavelengths and the type of alloying sample (MS) with ZnWO 4. • All samples exhibit a wide-ranging emission in the blue-green region. • The examined samples become more sensitive to daylight. [ABSTRACT FROM AUTHOR]

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[Display omitted] • This paper introduces four two-dimensional inorganic biphenylene-like structures based on ZnS and CdS. • Phonon dispersion and ab initio molecular dynamics (AIMD) simulations were used to demonstrate the dynamical and thermal stabilities. • All evaluated structures are ultra-wideband gap semiconductors, with band gap energy values from 3.59 to 5.34 eV. • p-BPN-ZnS demonstrated the highest Young modulus (Y x /Y y = 25.295/34.874 N/m), followed by p-BPN-CdS (Y x /Y y = 15.286/21.339 N/m). • Notably, b-BPN-ZnS displayed a particular characteristic, a negative Poisson ratio (ν x /ν y = -0.008/-0.030), being an auxetic material. This study presents four novel inorganic structures based on the biphenylene network (BPN): planar BPN-ZnS (p-BPN-ZnS) and BPN-CdS (p-BPN-CdS) and buckled BPN-ZnS (b-BPN-ZnS) and BPN-CdS (b-BPN-CdS). Cohesive energy analyses reveal that structural buckling enhances stability, and a perturbation is necessary to obtain planar lattices. Phonon dispersion and ab initio molecular dynamics (AIMD) simulations demonstrated the dynamical and thermal stabilities. ZnS-based structures exhibited more pronounced charge accumulation and depletion than CdS. All evaluated structures are ultra-wideband gap semiconductors, with band gap energy values of 4.33, 5.34, 3.59, and 4.30 eV (at HSE06 level) for p-BPN-ZnS, b-BPN-ZnS, p-BPN-CdS, and b-BPN-CdS, respectively. p-BPN-ZnS demonstrated the highest Young modulus (Y x /Y y = 25.295/34.874 N/m), followed by p-BPN-CdS (Y x /Y y = 15.286/21.339 N/m). On the other hand, b-BPN-ZnS and b-BPN-CdS exhibit lower Young Modulus, Y x /Y y = 4.135/14.709 and 11.842/8.218 N/m, respectively. Notably, b-BPN-ZnS displayed a particular characteristic, a negative Poisson ratio (ν x /ν y = -0.008/-0.030), being an auxetic material. This report is expected to stimulate both theoretical and experimental researchers in the prediction and development of new inorganic materials based on the biphenylene network. [ABSTRACT FROM AUTHOR]

Abstract Cu2ZnSnS4 (CZTS)-based solar cells show a promising performance in the field of sunlight-based energy production system. To increase the performance of CZTS-based solar cell, buffer layer optimization is still an obstacle. In this work, numerical simulations were performed on structures based on CZTS absorber layer, ZnO window layer, and transparent conducting layer n-ITO with different buffer layers using SCAPS-1D software to find a suitable buffer layer. Cadmium sulfide (CdS), zinc sulfide (ZnS) and their alloy cadmium zinc sulfide (Cd0.4Zn0.6S) were used as potential buffer layers to investigate the effect of buffer thickness, absorber thickness and temperature on open-circuit voltage (V oc), short-circuit current (J sc), fill factor (FF) and efficiency (η) of the solar cell. The optimum efficiencies using these three buffer layers are around 11.20%. Among these three buffers, Cd0.4Zn0.6S is more preferable as CdS suffers from toxicity problem and ZnS shows drastic change in performance parameters. The simulation results can give important guideline for the fabrication of high-efficiency CZTS solar cell.

Through first-principles investigations, we examine variations in the atomic crystal structure, thermal stability, electronic structure, and piezoelectric properties of wurtzite ZnS and CdS under in-plane strain. We specifically aim to elucidate the distinct effects arising from two relaxation modes: elastic and non-elastic. Our analyses reveal that the in-plane strain-induced deformation behaviors and performance changes in these sulfides are remarkably similar, attributable to the similar atomic arrangements, anionic sulfur elements, and analogous cation electronic configurations. However, following non-elastic relaxation, enhanced robustness emerges in the lattice volume and chemical bonding, alongside stronger thermal stability and attenuated modifications in the piezoelectric coefficient. We posit that these marked discrepancies from elastic relaxation may originate from subtle differences in the electronegativities and d -orbital electron configurations between the Zn2+ and Cd2+ cations. By offering fundamental new insights into the atomic-scale relaxation phenomena in wurtzite binaries, this work significantly furthers the fundamental understanding of structure-property relationships in these materials. Moreover, delineating the precise impacts of elastic versus non-elastic relaxation serves as an effective tuning methodology to engineer the piezoelectric and electronic traits of sulfide compounds for cutting-edge applications. [Display omitted] • In-plane strain causes prominent changes in atomic arrangement, electronic and piezoelectric properties of wurtzite Zn(Cd)S. • Cation's electronegativity and electron configurations relate to responses of wurtzite Zn(Cd)S to in-plane strain. • Non-elastic relaxation leads to higher robustness in volume, chemical bond, thermal stability and piezoelectric coefficient. [ABSTRACT FROM AUTHOR]

The development of electrocatalysts is a pivotal aspect of advancing electrochemical (EC) CO 2 recycling. In this research, we incorporated cadmium sulfide (CdS) onto a cadmium (Cd) support and subsequently enhanced it with the deposition of Au, Ag, and Cu using sputter deposition techniques. These modified catalysts were then rigorously evaluated for their performance in EC CO 2 reduction. The primary products were formate, CO, and H 2. Notably, CdS/Cd demonstrated significantly superior performance in EC CO 2 reduction compared to the unmodified Cd catalyst. Furthermore, the deposition of transition metals drastically suppressed H 2 production, while Ag and Cu deposition enhanced CO production in NaHCO 3 conditions. For Au/CdS/Cd in phosphate condition, CH 4 and alkane-dominant C 2–7 hydrocarbons were significantly produced and explained by the conventional Fischer–Tropsch synthesis paths. After EC CO 2 reduction, CdS/Cd surface was observed to be recrystallized to CdCO 3 with a morphology of cubes. Photocatalytic CO 2 reduction over CdS/Cd produced CO, CH 4 , CH 3 OH, and alkene-dominant C 2–6 hydrocarbons. Additionally, a zinc sulfide (ZnS) on Zn electrode was prepared and tested, which showed H 2 and CO as main products, but no formate was observed. [Display omitted] • CdS/Cd was modified with Au, Ag, and Cu and tested in electrochemical CO 2 reduction. • Major products of CO, formate, and H 2 were significantly altered by transition metal-modification. • Au-modification produced C 2–7 hydrocarbons explained by the conventional Fischer–Tropsch synthesis. • After electrochemistry, CdS surface became recrystallized to CdCO 3 with cuboid/cube structures. • ZnS showed only CO and H 2 with no formate production. [ABSTRACT FROM AUTHOR]

In this work, mesoporous CdS (130.7 m2/g) was prepared; then, ZnS was deposited by chemical bath deposition (CBD) and successive ionic layer adsorption and reaction (SILAR) method, to get CdS–ZnS(C) and CdS–ZnS(S), respectively. Subsequently, the highest efficient binary hybrid was sensitized with polyaniline to produce CdS–ZnS–PANI for the first time. XRD and EDX analyses confirmed the coating of CdS with ZnS using CBD and SILAR method. The careful examination for the surface morphology of the binary hybrids illustrated that CdS–ZnS(S) has uniform morphology and the CdS nanoparticles are homogeneously overcoated with ZnS. In contrast, CdS–ZnS(C) exhibits inhomogeneous surface, where there are ZnS particles that aggregate together and there is another region which contains ZnS deposited onto CdS. The estimated band gap of CdS, CdS–ZnS(S), and CdS–ZnS–PANI was 2.36 eV, 2.44 eV, and 1.9 eV, respectively. The removal efficiency for cationic and anionic dyes single and/or in combination using CdS, ZnS, CdS–ZnS(C), CdS–ZnS(S), PANI, and CdS–ZnS–PANI was studied. The effect of the amount of ZnS loaded by SILAR process on the activity of the CdS–ZnS(S) was presented. The results proposed that CdS–ZnS(S) exhibits selective adsorption and high removal efficiency for cationic dye compared to CdS–ZnS(C) due to higher negative zeta potential and large surface area. The CdS–ZnS–PANI ternary nanocomposite showed uptake efficiency of 96.7% for cationic dye (MB) and 94.3% for anionic dye (MO) in a mixed dye solution after 10 min. Finally, the possible adsorption mechanism was proposed. [ABSTRACT FROM AUTHOR]

In recent years, tantalum oxynitride (TaON) semiconductor as one of the most efficient photocatalysts has been studied intensively owing to the appropriate potentials for overall solar water splitting. In this work, ZnS/CdS/γ-TaON composite photocatalysts with wide light response were successfully prepared by nitridation of Ta2O5 at 800 °C in a wet NH3 flowing and subsequently deposition CdS and ZnS quantum dots. The powders were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), UV–vis diffuse reflection spectroscopy (DRS), N2 adsorption–desorption isothermals, X-ray photoelectron spectroscopy (XPS), and so on. The photocatalytic property for hydrogen production was also studied. The results indicated that CdS and ZnS quantum dots with a diameter of 3–8 nm were uniformly dispersed on the surface of γ-TaON, which enlarged the spectral response of the ZnS/CdS/γ-TaON photocatalysts. And the optimized H2 evolution rate of ZnS/CdS/γ-TaON composite (839.6 μmol h−1 g−1) is about 14 times higher than that of CdS/γ-TaON in the absence of any noble-metal cocatalyst and 47 times higher than that of Pt loaded γ-TaON sample. The enhanced photocatalytic activity is attributed to the higher separation efficiency of electrons and holes with the heterogeneous junction between ZnS, CdS, and γ-TaON. Besides, the presence of γ-TaON and ZnS also prevent the photocorrosion of CdS. The results provide a new insight for developing the TaON-based nanocomposite photocatalysts with enhanced stability and excellent photocatalytic H2 production activity. Highlights: ZnS/CdS/γ-TaON nanocomposite photocatalysts had been successfully fabricated though deposition of CdS and ZnS quantum dots over γ-TaON nanoparticles. CdS and ZnS/CdS significantly improve the photocatalytic activity of γ-TaON. The optimized H2 evolution rate of ZnS/CdS/γ-TaON composite is about 14 times higher than that of CdS/γ-TaON in the absence of any noble metal cocatalyst and 47 times higher than that of Pt loaded γ-TaON sample. The band structures and the possible transfer mechanism were proposed. [ABSTRACT FROM AUTHOR]

Abstract A photoelectrode has to generate high enough photovoltage by efficient charge separation spontaneously to split water. In this study, cascade band structures with CdS and ZnS applied to CuIn x Ga 1-x Se y S 2-y (CIGS) photoelectrode of water splitting. The morphology, the electronic and the chemical state of CIGS heterojunction films have been characterized by a scanning electron microscopy, X-ray photoelectron spectroscopy, and ultraviolet photoelectron spectroscopy. The CIGS/CdS/ZnS photocathode shows ∼400 mV anodic shift of onset potential and 0.028% efficiency for solar to hydrogen conversion when it couples with a WO 3 /BiVO 4 /Co-P i photoanode for water splitting without external bias potential. [ABSTRACT FROM AUTHOR]

A 3-layer graded-bandgap solar cell with glass/FTO/ZnS/CdS/CdTe/Au structure has been fabricated using all-electrodeposited ZnS, CdS and CdTe thin layers. The three semiconductor layers were electrodeposited using a two-electrode system for process simplification. The incorporation of a wide bandgap amorphous ZnS as a buffer/window layer to form glass/FTO/ZnS/CdS/CdTe/Au solar cell resulted in the formation of this 3-layer graded-bandgap device structure. This has yielded corresponding improvement in all the solar cell parameters resulting in a conversion efficiency >10% under AM1.5 illumination conditions at room temperature, compared to the 8.0% efficiency of a 2-layer glass/FTO/CdS/CdTe/Au reference solar cell structure. These results demonstrate the advantages of the multi-layer graded-bandgap device architecture over the conventional 2-layer structure. In addition, they demonstrate the effective application of the two-electrode system as a simplification to the conventional three-electrode system in the electrodeposition of semiconductors with the elimination of the reference electrode as a possible impurity source.

Highly photoactive merocyanine 540 is revealed to form charge transfer complex with zinc sulphide and cadmium sulphide nanocrystals confirmed by FT-IR Spectroscopy, Fluorescence emission and UV-Visible spectrophotometer. The semiconducting nanocrystals were synthesized by co-precipitation method and characterized by Fluorescence emission spectroscopy, UV-Visible spectroscopy, Scanning electron microscopy (SEM), X-ray spectroscopy and Energy dispersive X-ray spectroscopy (EDAX). Merocyanine, in different concentrations was chemisorbed on the surface of ZnS and CdS nanomaterial. ZnS and CdS nanoparticles were used in hybrid solar cells in combination with organic polymer. These cells performed good efficiency at (6 × 10 −6  M) dye concentration. The decreased power conversion efficiency with short circuit current density below and above the optimal merocyanine concentration (6 × 10 −6  M) may be due to aggregation of merocyanine dye on CdS nanocrystals and subsequent self-quenching phenomena among dye molecules. The power conversion efficiency of the devices fabricated from P3HT-CdS-MC540 was higher than devices fabricated from P3HT-ZnS-MC540 because of particle size effect. [ABSTRACT FROM AUTHOR]

In the present work, we have employed an organometallic method for preparing CdS and ZnS nanoparticles (NPs). In the synthesis of CdS and ZnS, Cadmium Oxide, Zinc Oxide and Sulfur are used as precursors. X-Ray diffraction (XRD) pattern confirms that the sample is crystalline structure with a hexagonal wurtzite phase. X-ray peak broadening analysis was used to estimate the crystallite sizes and lattice strain using the Williamson-Hall (W-H) analysis. The crystallinity of the samples, lattice fringes and the formation of agglomerated nanoparticles clearly showed using the high resolution TEM technique. The elemental composition of CdS and ZnS are determined by energy dispersive X-ray spectroscopy (EDS). Fourier Transform Infra-Red spectra (FTIR) are measured for identification of chemical bonds in the nanomaterial, while Raman spectroscopy was performed to study the confinement of the optical phonon modes in the QDs. The diameters of particles are calculated using yu equation. These diameters are found to lie in the range of 2.62 - 2.73 nm for CdS and of 2.88 - 4.09 nm for ZnS NPs. Absorption peaks are red-shifted gradually as the particle size increased with an increment equals 5 nm for CdS and 19 nm for ZnS. Zinc sulfide NPs resulted better enhancement of the photoluminescence than that of Cadmium Sulfide NPs. [ABSTRACT FROM AUTHOR]

The dependence of Zn precursors using zinc sulfate (ZnSO 4 ), zinc acetate (Zn(CH 3 COO) 2 ), and zinc chloride (ZnCl 2 ) on the characteristics of the chemical bath deposited ZnS thin film used as a buffer layer of Cu(In,Ga)Se 2 (CIGS) thin film solar cell was studied. It is found that the ZnS film deposition rate increases with higher stability constant during decomplexation reaction of zinc ligands, which affects the crack formation and the amount of sulfur and oxygen contents within the film. The band gap energies of all deposited films are in the range of 3.40–3.49 eV, which is lower than that of the bulk ZnS film due to oxygen contents within the films. Among the CIGS solar cells having ZnS buffer layers prepared by different Zn precursors, the best cell efficiency with 9.4% was attained using Zn(CH 3 COO) 2 precursor due to increased V oc mainly. This result suggests that [Zn(NH 3 ) 4 ] 2+ complex formation should be well controlled to attain the high quality ZnS thin films. [ABSTRACT FROM AUTHOR]

All-electrodeposited ZnS, CdS and CdTe thin layers have been incorporated in a graded bandgap solar cell structure of glass/FTO/ n- ZnS/ n- CdS/ n- CdTe/Au have been fabricated and an average conversion efficiency of 14.18% was achieved under AM1.5 illuminated condition. Based on former work in which 10% conversion efficiency was reported, optimisation has been made to the semiconductor layers, precursors, thicknesses and the post-growth treatment. These results demonstrate the advantages of multi-layer graded bandgap device configuration and the inclusion of gallium based post-growth treatment (CdCl 2 +Ga 2 (SO 4 ) 3 ) on the CdS/CdTe-based device structure. The fabricated devices were characterised using both current-voltage (I-V) and capacitance-voltage (C-V) techniques. Under dark I-V condition, a rectification factor ( R.F. ) of 10 4.8 , ideality factor ( n ) of 1.60 and a barrier height ( ϕ b ) >0.82 eV were observed. Under AM1.5 illuminated I-V condition, short-circuit current density ( J sc ) of 34.08 mA cm −2 , open-circuit voltage ( V oc ) of 730 mV, fill-factor ( FF ) of 0.57 and conversion efficiency of 14.18% were observed. Under dark C-V condition, doping density ( N D ) of 7.79 × 10 14  cm −3 and a depletion width ( W ) of 1092 nm were achieved. In addition, the work demonstrates the capability of two-electrode system as a simplification to the conventional three-electrode system in the electrodeposition of semiconductors. [ABSTRACT FROM AUTHOR]

CdS quantum dot-sensitized solar cells (QDSCs) have been fabricated and their photoanode optimized by altering the thickness of the photoelectrode and CdS deposition conditions and applying a ZnS electron-blocking layer and TiO hollow spheres. Hydrothermally grown TiO nanocrystals (NCs) with dominant size of 20 nm were deposited as a sublayer in the photoanode with thickness in the range from 5 μm to 10 μm using a successive ionic layer adsorption and reaction (SILAR) method. The number of deposition cycles was altered over a wide range to obtain optimized sensitization. Photoanode thickness and number of CdS sensitization cycles around the optimum values were selected and used for ZnS deposition. ZnS overlayers were also deposited on the surface of the photoanodes using different numbers of cycles of the SILAR process. The best QDSC with the optimized photoelectrode demonstrated a 153% increase in efficiency compared with a similar cell with ZnS-free photoanode. Such bilayer photoelectrodes were also fabricated with different thicknesses of TiO sublayers and one overlayer of TiO hollow spheres (HSs) with external diameter of 500 nm fabricated by liquid-phase deposition with carbon spheres as template. The optimization was performed by changing the photoanode thickness using a wide range of CdS sensitizing cycles. The maximum energy conversion efficiency was increased by about 77% compared with a similar cell with HS-free photoelectrode. The reason was considered to be the longer path length of the incident light inside the photoanode and greater light absorption. A ZnS blocking layer was overcoated on the surface of the bilayer photoanode with optimized thickness. The number of CdS sensitization cycles was also changed around the optimized value to obtain the best QDSC performance. The number of ZnS deposition cycles was also altered in a wide range for optimization of the photovoltaic performance. It was shown that the maximum efficiency was increased by about 55% compared with a similar QDSC with ZnS-free bilayer photoanode. The final improvement was carried out by applying methanol-based Cd precursor solution in the SILAR deposition process. The best photoanodes from the previous stages were selected and used in this sensitizing process. Besides, nanocrystalline TiO sublayers with different thicknesses were applied for further optimization. The results revealed that maximum power conversion efficiency of 3.7% was achieved as a result of such improvement, for a QDSC with optimized double-layer photoanode including TiO HSs and NCs and ZnS blocking layer. [ABSTRACT FROM AUTHOR]

In this paper, ZnS/CdS core/shell nanotubes were successfully synthesized by combining hydrothermal treatment and ion exchange conversion, and the significant influence of CdS content in the shell on photo absorption and photocatalytic activity was also investigated. The core/shell nanotubes structure of CdS deposition on both sides of ZnS nanotube was confirmed by scanning electron microscopy (SEM) and high resolution transmission electron microscopy (HRTEM). The room temperature PL spectra of ZnS/CdS core/shell nanotubes indicated that CdS on the shell can reduce the recombination of photon-generated electron and hole. The photocatalytic activity tests prove that ZnS/CdS nanotubes have much higher photocatalytic hydrogen production activity than ZnS nanotube and CdS nanotube. Under the irradiation of visible light, the highest photocatalytic hydrogen production rate of 110 μmol h −1 g −1 is observed over the ZnS/CdS core/shell nanotubes with CdS/ZnS molar ratio of 1:4, which is about 11.02 and 5.56 times more active than ZnS nanotube and CdS nanotube, respectively. The improved performance of ZnS/CdS samples can be due to the strong photo response in the visible light region and the efficient separation of electron–hole pairs. [ABSTRACT FROM AUTHOR]

A stable aqueous colloidal solution of core-shell CdS-ZnS nanoparticles is obtained via the chemical condensation of carboxyl-containing diamine complexone (disodium salt of ethylenediaminetetraacetic acid). CdS nanoparticles coated with ZnS exhibit 20 times greater luminescence and more stability, compared to CdS nanoparticles without ZnS on their surface. [ABSTRACT FROM AUTHOR]

A fluorescent probe based on CdS/ZnS core/shell heterostructure nanowires decorated with 2-Amino-3-sulfhydrylpropanoic acid (2A-3SHPA) has been designed for the detection of antimony ions at nanomolar levels for the first time. The structural and morphological characterizations indicated that zinc sulfide shell with a zinc blend cubic structure was epitaxially grown along the radial core of the wurtzite hexagonal cadmium sulfide structure with high quality interface via cation exchange mechanism. The optical studies revealed that the developed CdS/ZnS core-shell nanowires have superior intense green luminescence emission at ambient temperature demonstrating efficient charge carriers recombination inside the CdS core. At the optimum conditions, the fluorescence intensity showed a linear regression against the antimony concentration along the range from 1 nM to 1000 nM with detection limit 1.2 × 10 −11 mol L −1 . The developed fluorescence probe exhibited high photo-stability against temperature up to 60 °C as well as storage time till 2 months. These superior characteristics may enable the developed core-shell nanowires to monitor the traces of antimony ions to evade their dangerous effect on the health such as albuminuria and glycosuria. [ABSTRACT FROM AUTHOR]

Zn(II) and Cd(II) metal complexes of 1-cyano-1-carboethoxyethylene-2,2-dithiolato–κ S , S ’–bis(N,N-dimethylthiourea–κ S ) have been synthesized and characterized with analytical and spectroscopic techniques. The complexes were thermolysed in hexadecylamine at 200 °C to prepare ZnS and CdS nanoparticles. The nanoparticles were characterized with scanning electron microscope (SEM), transmission electron microscope (TEM), and powder X-ray diffraction (p-XRD). TEM images showed spherically shaped nanoparticles, whose sizes are in the range 4.33–7.21 nm for ZnS and 4.95–7.7 nm CdS respectively and XRD confirmed cubic crystalline phases for the nanoparticles. The optical band gap energy evaluated from the absorption spectra are 2.88 eV (430 nm) and 2.81 eV (440 nm) for the ZnS and CdS nanoparticles respectively. The as-prepared metal sulfide nanoparticles were further incorporated into polyvinyl alcohol (PVA) to give ZnS/PVA and CdS/PVA composites. The polymer nanocomposites were studied to investigate their morphology and thermal properties relative to the pure PVA. XRD diffractions indicated that the crystalline phases of the nanoparticles and the sizes in PVA matrices remained unaltered. Infra-red spectra studies revealed interactions between the PVA and the metal sulfide nanoparticles and TGA studies show that the ZnS/PVA and CdS/PVA nanocomposites exhibit better thermal stability than the pure PVA. [ABSTRACT FROM AUTHOR]

A simple wet chemistry method was employed for the synthesis of graphene oxide-metal sulfide composites. The obtained products were characterized by X-ray diffraction, transmission electron microscopy, X-ray photoelectron spectroscopy, nitrogen absorption–desorption specific surface area and UV–Vis spectroscopy. The study indicates that sulfides nanorods were well dispersed on the graphene oxide nanosheets in the graphene oxide-metal sulfide composites. It was found that the specific surface area of the composites increased with the introduction of graphene oxide. The as-synthesized graphene oxide-metal sulfide composites were used as photocatalysts for the color removal of methyl orange under UV light irradiation. The results indicated that the graphene oxide-metal sulfide composites exhibited improved photocatalytic activity to pure sulfides and commericial sulfides, with nearly 95% and 90% of methyl orange degraded after irradiation for 15 min, respectively. The excellent photocatalytic activity of the composites can be ascribed to the high specific surface area and the reduction of photoinduced electron–hole pair recombination due to the introduction of graphene oxide. With the help of various radical scavengers, O 2 − and h + were proved to be the main reactive species for the color removal of methyl orange. [ABSTRACT FROM AUTHOR]