Ternary CdS Research Articles

Shaping the Future of the Neurotransmitter Sensor: Tailored CdS Nanostructures for State-of-the-Art Self-Powered Photoelectrochemical Devices.

Semiconductor-based photoelectrochemical (PEC) test protocols offer a viable solution for developing efficient individual health monitoring by converting light and chemical energy into electrical signals. However, slow reaction kinetics and electron-hole complexation at the interface limit their practical application. Here, we reported a triple-engineered CdS nanohierarchical structures (CdS NHs) modification scheme including morphology, defective states, and heterogeneous structure to achieve precise monitoring of the neurotransmitter dopamine (DA) in plasma and noninvasive body fluids. By precisely manipulating the Cd-S precursor, we achieved precise control over ternary CdS NHs and obtained well-defined layered self-assembled CdS NHs through a surface carbon treatment. The integration of defect states and the thin carbon layer effectively established carrier directional transfer pathways, thereby enhancing interface reaction sites and improving the conversion efficiency. The CdS NHs microelectrode fabricated demonstrated a remarkable negative response toward DA, thereby enabling the development of a miniature self-powered PEC device for precise quantification in human saliva. Additionally, the utilization of density functional theory calculations elucidated the structural characteristics of DA and the defect state of CdS, thus establishing crucial theoretical groundwork for optimizing the polymerization process of DA. The present study offers a potential engineering approach for developing high energy conversion efficiency PEC semiconductors as well as proposing a novel concept for designing sensitive testing strategies.

High performance photodetector based on CdS/CdS0.42Se0.58 nanobelts heterojunction

The ternary alloy CdS x Se1−x combines the physical properties of CdS and CdSe, and its band gap can be adjusted by changing the element composition. The alloy has charming photoelectric properties as well as potential application value in photoelectric devices. In this work, the CdS/CdS0.42Se0.58 nanobelt (NB) heterojunction device was prepared by chemical vapor deposition combined with a typical dry transfer technique. The heterojunction photodetector shows high light switching ratio of 6.79 × 104, large spectral responsivity of 1260 A W−1, high external quantum efficiency of 2.66 × 105% and large detectivity of 7.19 × 1015cm Hz1/2 W−1 under 590 nm illumination and 3 V bias. Its rise and decay time is about 45/90 μs. The performance of the heterojunction photodetector was comparable or even better than that of other CdS(Se) based photodetector device. The results indicate that the CdS/CdS0.42Se0.58 NB heterojunction possesses a promising potential application in high performance photodetectors.

High-performance photodetectors based on Au nanoislands decorated CdSSe nanobelt

Ternary alloy CdS<sub><i>x</i></sub>Se<sub>1–<i>x</i></sub> has the physical properties of CdS and CdSe, and its band gap can be adjusted by changing the component ratio of the elements. The alloy has excellent photoelectric properties and has potential application in optoelectronic devices. Although one has made some research progress of the CdSSe-based photodetectors, their performances are still far from the commercial requirements, so how to improve the performance of the device is the focus of current research. In this work, a single crystal CdS<sub>0.42</sub>Se<sub>0.58</sub> nanobelt device is first prepared by thermal evaporation. Under 550 nm illumination and 1 V bias, the ratio of photocurrent to dark current of the device is 1.24×10<sup>3</sup>, the responsivity arrives at 60.1 A/W, and the external quantum efficiency reaches 1.36×10<sup>4</sup>%, and the detectivity is 2.16×10<sup>11</sup> Jones. Its rise time and fall time are about 41.1/41.5 ms, respectively. Secondly, after the CdSSe nanobelt is decorated by Au nanoislands, the optoelectronic performance of the device is significantly improved. Under 550 nm illumination and 1 V bias, the <i>I</i><sub>p</sub>/<i>I</i><sub>d</sub> ratio, responsivity, external quantum efficiency and detectivity of the device are increased by 5.4, 11.8, 11.8 and 10.6 times, respectively, and the rise time and fall time are both reduced to half of counterparts of single CdSSe nanobelt. Finally, the microscopic physical mechanism of the enhanced optoelectronic performance of the device is explained based on localized surface plasmon resonance of Au nanoislands. After the combination of gold nanoislands and CdSSe nanobelt, the difference in Fermi level between them results in the transfer of electrons from CdSSe nanobelt to Au nanoislands, thus forming an internal electric field at the interface, which is directed from CdSSe nanobelt to Au nanoislands. Under illumination, the electrons in the Au nanoislands acquire enough energy to jump over the Schottky barrier because of localized surface plasmon resonance. These photoexcited hot electrons are trapped and stored in extra energy levels above the conduction band minimum, and then are cooled down to the band edge, thus realizing the transfer of electrons from Au nanoislands to CdSSe nanobelt. Moreover, the internal electric field also greatly promotes the transfer of hot electrons from Au nanoislands to CdSSe nanobelt, and inhibits the recombination of carriers at the interface, resulting in large photocurrent. Our work provides an effective strategy for fabricating high-performance photodetectors without increasing the device area.

Greatly enhanced photocatalytic hydrogen production on CdS/(Pt/g-C3N4) via dual functions of Pt on semiconductors interface

CdS and g-C3N4 are famous semiconductors in photocatalytic hydrogen evolution, however, their low efficiencies limit their further application. Here, a highly efficient ternary catalyst CdS/(Pt/g-C3N4) was reported and its photocatalytic hydrogen production activity reached up to 1465.9 μmol/h/g, which is 5.3 times of Pt/CdS and 4.0 times of Pt/g-C3N4, respectively. TEM and HRTEM images demonstrate the Pt nanoparticles exists on the interface of between CdS and g-C3N4 acting as a cocatalyst for hydrogen evolution. SPV spectra and electrochemical tests demonstrate that Pt as bridge between CdS and g-C3N4 also accelerates the electrons transforming which benefits for the inhibition of the recombination of photoexcited electrons and holes. This study demonstrated the dual roles of interface Pt and provides a new method to design a highly efficient photocatalyst.

Strategy modulation of energy transfer for the plasmon-promoted hydrogen evolution in ternary CdS–Au–MoS2

Nano noble metals with surface plasmon resonance effect have been widely applicated in photocatalytic hydrogen production, however, the poor oxidation/reduction efficiency is the major obstruction for the extensive application of the water splitting. In this study, the ternary nanocomposite, CdS–Au–MoS2, is structured for the strategic modulation of the energy transfer of the incident light. Comparing with pristine CdS nanowires, an obvious improvement with the maximum H2 evolution rate of 11.43 mmol·g−1·h−1 was obtained after the conjunction of Au nanorods, and the photocatalytic activity was further promoted about ∼2.04 times through the surface modification of the MoS2 quantum dots. A positive synergistic effect of the plasmon and co-catalyst was proposed, where the Au nanorods acted as the source of hot electrons while the MoS2 quantum dots served as the active sites for hydrogen evolution reaction. Compared with similar nanostructures reported previously, the present superior photoactivity response is ascribed to the plasmon-promoted effect combined with the co-catalyst, which corresponds to the electric field distribution of the finite-difference-time-domain simulation. These intriguing results expanded the comprehensive understanding of plasmon-assisted photochemistry and provided a promising strategy for the rational design of novel plasmonic photocatalysts.

A Comparative Performance Evaluation of Ternary ZnxCd1-xS and Binary CdS window Layer in CIGS Solar Cell

A Comparative Performance Evaluation of Ternary ZnxCd1-xS and Binary CdS window Layer in CIGS Solar Cell

Ternary CdS1–xSexnanocrystals formed in Cd‐doped As–Se–S films due to photoenhanced diffusion during micro‐Raman measurement

AbstractMicro‐Raman spectra of amorphous As–Se–S:Cd films prepared by thermal evaporation on silicon and silicate glass substrates measured at different laser power densities show the formation of CdS1–xSexnanocrystals in the As–Se–S:Cd film under laser beam illumination due to a photoinduced material transfer and photoenhanced diffusion in the laser spot area. The material transfer and the photoenhanced diffusion are caused by a non‐thermal interaction of light with the amorphous As–Se–S:Cd films. The chemical composition of the CdS1–xSexnanocrystals can be determined from the difference of the CdSe‐like and CdS‐like LO phonon wavenumbers in the Raman spectra. The photoluminescence peak energies are in agreement with the CdS1–xSexcomposition, with the average nanocrystal size being somewhat above the exciton Bohr radius.

Synergetic Hybridization Effect of Homogeneously Mixed Inorganic and Graphene Nanosheets on the Photocatalytic Activity of Semiconductor

Using the homogeneous colloidal mixture of conductive metal oxide nanosheet (NS) and reduced graphene oxide (rGO) NS as hybridization matrices provides universal way of optimizing the photocatalyst functionality of semiconductor nanocrystals. A self‐assembly between CdS quantum dots (QDs) and RuO2/rGO NSs yields strongly coupled ternary nanohybrids with enhanced photocatalytic activity and increased porosity. Even with its lower RuO2 content, the ternary CdS−RuO2/rGO nanohybrid exhibits notably higher photocatalytic activities for visible‐light‐induced H2 evolution and photocurrent generation than binary CdS−RuO2/rGO homologues, underscoring the synergetic hybridization effect of flexible rGO and hydrophilic RuO2 NSs. In comparison with single RuO2/rGO NSs, their homogeneous mixture can play better roles of photosensitizers and cocatalysts, which is mainly responsible for remarkable improvement of photocatalytic activity upon the cohybridization with mixed RuO2/rGO NSs. The current study underscores that cohybridization with complementary inorganic and graphene NSs can provide an efficient and economically feasible methodology to explore novel high‐performance catalyst materials.

Structural stability and magnetism in Cd0.875Mn0.125Z (Z = S, Se)

Based on the theory of first principles spin-density functional calculations within the framework of the CA local density approximation, we examine the structural, elastic, electronic and magnetic properties of ternary alloys CdS and CdSe doped with manganese at x = 0.125. We found that Cd0.875Mn0.125Z (S, Se) materials are ferromagnetic in nature. The total and partial curves of density and the electronic bond structures of states show that Cd0.875Mn0.125Z (S, Se) are ferromagnetic and can be potentially good candidates for the spintronic applications.

Precursor aging effect on the properties of CdZnS films

Nanostructured ternary Zn-doped CdS (CdZnS) thin films were fabricated from fresh and aged (1, 2, 3 and 4 days) starting solutions by the spray pyrolysis technique using a perfume atomizer. X-ray diffraction studies showed that the films are polycrystalline in nature exhibiting hexagonal crystal structure with a (0 0 2) preferential orientation. SEM images showed that the film prepared from 1 day aged solution possesses randomly oriented CdS crystallites of elongated needle shape. The optical band gap values exhibit a red shift with aging time of the precursor solution. A minimum resistivity of 3.94 × 10−3 Ω cm is obtained for the film prepared from 1 day aged solution. The obtained results infer that the CdZnS film prepared from 1 day aged solution exhibits better physical properties.

Roles of MoS2 and Graphene as Cocatalysts in the Enhanced Visible‐Light Photocatalytic H2 Production Activity of Multiarmed CdS Nanorods

AbstractThe incorporation of cocatalysts into semiconductors is proved to be an effective approach to improving the efficiency of the photocatalytic H2 production. Noble metals such as Pt have been widely used as cocatalysts and can significantly improve the performance of photocatalytic H2 production. However, owing to the high cost and low abundance, the use of Pt in practical applications is restricted. Herein, we report two well‐known 2 D layered materials, MoS2 and graphene, as highly active cocatalysts for H2 production in CdS‐based photocatalytic systems. The CdS–MoS2 and CdS‐MoS2–graphene nanocomposites were prepared by using a facile two‐step solvothermal method, and the morphologies of CdS and MoS2 can be well controlled. The as‐prepared binary CdS–MoS2 nanocomposite exhibits the enhanced visible‐light photocatalytic activity for H2 production in lactic acid aqueous solution compared with a CdS–graphene nanocomposite and a conventional platinized CdS photocatalyst. Moreover, the ternary CdS–MoS2–graphene nanocomposite achieves the highest visible‐light photocatalytic H2 production activity of 621.3 μmol h−1 and the apparent quantum efficiency of 54.4 % at λ=420 nm. The enhanced photocatalytic activity of the CdS–MoS2–graphene nanocomposite can be primarily attributed to the positive synergistic effect between graphene sheets and thin MoS2 nanoplates. The graphene sheets can accelerate the efficient electron transfer from CdS nanorods to the active edge sites of MoS2 nanoplates, and the nanosized MoS2 can facilitate the photogenerated electrons participating in the photocatalytic H2 production. The mechanisms for improving the photocatalytic performance of the MoS2‐ and/or graphene‐modified CdS nanocomposites were proposed by using the electrochemical analysis and photoluminescence measurement.

Enhancing the visible light photocatalytic performance of ternary CdS–(graphene–Pd) nanocomposites via a facile interfacial mediator and co-catalyst strategy

By embedding noble metal palladium (Pd) into the interfacial layer matrix of graphene (GR) and semiconductor CdS, we have successfully constructed ternary CdS–(GR–Pd) nanocomposites with intimate interfacial contact. The CdS–(GR–Pd) nanocomposites show remarkably enhanced photocatalytic activity toward selective redox reactions under visible light irradiation as compared to blank-CdS and the optimum binary CdS–GR. It is revealed that the photocatalytic performance enhancement of CdS–(GR–Pd) is ascribed to the optimized spatial charge carrier transfer across the interface resulting from the introduction of Pd nanoparticles as mediators into the interfacial layer between GR and CdS. One role of Pd is to serve as electron reservoir to directly trap photogenerated electrons from CdS and the other role is as interfacial mediator to promote electron relay in the ternary CdS–(GR–Pd) photocatalysts along with conductive graphene as dual co-catalysts. Moreover, the negative light “shielding effect” of GR can be partially counterbalanced through such a facile strategy. This work substantiates the feasibility of adopting the “interfacial-mediator” strategy to optimize the interfacial charge carriers transfer pathway and efficiency for improved photoactivity of GR–semiconductor nanocomposites toward target photoredox reactions.

Fabrication and properties of CuInSe2/AgInSe2/CdS double heterojunction cascade solar cells

This paper reports the first study of the photoelectric properties of a double heterojunction cascade solar power converter based on the ternary compounds CuInSe2, AgInSe2, and CdS. We evaluate the photoelectric parameters of individual elements and a double-heterojunction converter. The efficiency of the cascade converter is η = 10.7%.

Composition-dependent ultra-high photoconductivity in ternary CdS x Se1−x nanobelts as measured by optical pump-terahertz probe spectroscopy

We employ optical pump-terahertz probe spectroscopy to investigate the composition-dependent photoconductivity in ternary CdS x Se1−x nanobelts. The observed carrier dynamics of CdS nanobelts display much shorter lifetime than those of ternary CdS x Se1−x nanobelts. This indicates the implementation of CdS nanobelts as ultrafast switching devices with a switching speed potentially up to 46.7 GHz. Surprisingly, ternary CdS x Se1−x nanobelts are found to exhibit much higher photoconductivity than binary CdS and CdSe. This is attributed to the higher photocarrier densities in ternary compounds. In addition, the presence of Se in samples resulted in prominent CdSe-like transverse optical (TO) phonon modes due to electron-phonon interactions. The strength of this mode shows a large drop upon photoexcitation but recovers gradually with time. These results demonstrated that growth of ternary nanostructures can be utilized to alleviate the high surface defect density in nanostructures and improve their photoconductivity. Open image in new window

Modeling and Simulation of Bonding and Optical Characters of Ternary Nanocrystals

In this paper, conformations of the ternary structures ZnSe(Te), ZnS(Te), ZnS(Se), CdSe(Te), CdS(Te) and CdS(Se) were optimized, and their orbital, spectra have been investigated at the B3LYP/LANL2DZ level. First, we have found some rules which agreed with experimental results. HOMO–LUMO gaps, WBI values and the wavelengths of the absorption peaks of ternary structures changed gradually with the ratio of Te, Se and S atoms in ternary structures. Second, analysis of Raman spectra revealed that doped structures had the spectra of two relevant binary clusters. Namely, Raman spectra of ternary ZnSe(Te) clusters had the Raman peaks of ZnSe and ZnTe. In this way, with the help of the Raman spectra, the formations of the ternary structures can be determined in experiment. This was important to estimate during synthesis progress. Finally, calculated results have proved that ZnS and CdS structures had the shorter wavelengths of the absorption peaks, the higher excited energies of singlets, and good stability.

Constructing Ternary CdS–Graphene–TiO2 Hybrids on the Flatland of Graphene Oxide with Enhanced Visible-Light Photoactivity for Selective Transformation

The ternary CdS–graphene–TiO2 hybrids (CdS–GR–TiO2) have been prepared through an in situ strategy on the flatland of graphene oxide (GO). The structure and properties have been characterized by a series of techniques, including X-ray diffraction (XRD), field-emission scanning electron microscopy (FE-SEM), transmission scanning electron microscopy (TEM), energy-dispersive X-ray spectroscopy (EDX), UV–vis diffuse reflectance spectra (DRS), electrochemical analysis, photoluminescence spectra (PL), nitrogen adsorption–desorption, and electron spin resonance spectra (ESR). Combined with our previous results, it is found that the introduction of the third-component TiO2 can maintain the morphology and porosity of the samples, whereas it is able to tune the energy band, increase the surface area, and facilitate the electron transfer, thus prolonging the lifetime of photogenerated carriers. Taking photocatalytic selective oxidation of various alcohols to their corresponding aldehydes as model reactions, the ternary CdS–GR–TiO2 hybrid exhibits enhanced photocatalytic activity compared with its foundation matrix binary CdS–GR. The improved photocatalytic performance can be attributed to the combined interaction of the longer lifetime of photogenerated electron–hole pairs, faster interfacial charge transfer rate, and larger surface area. In addition, a possible reaction mechanism has been proposed. This work indicates that the careful design of graphene–based composites by coupling graphene to suitable, multiple semiconductors allows the achievement of more efficient photocatalysts, which may have the great potential to improve the capacity for photocatalytic processes significantly. As a proof-of-concept, it is expected that this work could offer new inroads into exploration and utilization of graphene–based nanocomposites as a fertile ground for energy conversion.

Surface ion transfer growth of ternary CdS1−xSex quantum dots and their electron transport modulation

We report a surface ion transfer method to synthesise ternary alloy CdS(1-x)Se(x) (0 ≤x≤ 1) quantum dots (QDs) in situ on TiO(2) nanoparticles. By tuning the content of selenium in such quantum dots, the optical absorption spectra can be controllably widened to cover the most of the visible light range. The electron transport of such QDs can be modulated by changing the interfacial electronic energy between CdS(1-x)Se(x) QDs and TiO(2) nanoparticles. The QDs with optimized selenium content (x = 0.72) give a balance between a broad optical absorption and a suitable energy band alignment. The homogenous alloy CdS(1-x)Se(x) QDs achieve a maximum light-harvesting efficiency over 90%, and generate a photocurrent density larger than 10 mA cm(-2), which is 2.6- and 1.4-times that of binary CdS and CdSe QDs sensitized photovoltaic devices.

Thermal treatment-dependent chemical composition of ternary CdS 1− xSe x nanocrystals grown in borosilicate glass

Variation of the chemical composition of ternary CdS 1− x Se x nanocrystals grown in borosilicate glass depending on the thermal treatment is studied by resonant Raman spectroscopy. It is shown that only for the nanocrystals with roughly equal content of substitutive S and Se chalcogen atoms (0.4< x<0.6) the nanocrystal composition is independent of the thermal treatment parameters. In other cases an increase of the thermal treatment temperature (625–700 °C) and duration (2–12 h) results in a considerable increase of the predominant chalcogen content in the nanocrystals.

Studies on growth and characterization of ternary CdS 1− xSe x alloy thin films deposited by chemical bath deposition technique

Ternary alloyed CdS 1− x Se x thin films of variable composition ‘ x’ were grown by the simple and economical chemical bath deposition technique. The as-grown thin films were characterized for structural, compositional, surface morphological, optical and electrical studies. The X-ray diffraction (XRD) patterns of the sample indicated that all the samples were polycrystalline in nature with hexagonal structure. Scanning electron microscopy (SEM) micrographs showed uniform morphology with spherical shaped grains distributed over entire glass substrate. EDAX studies confirmed that the CdS 1− x Se x films were having approximately same stoichiometry initially as well as finally. Room temperature optical measurements showed that band gap engineering could be realized in CdS 1− x Se x thin films via modulation in composition ‘ x’. Electrical resistivity of CdS 1− x Se x thin films for various compositions was found to be low. The broad and fine tunable band gap properties of ternary CdS 1− x Se x thin films have potential applications in opto-electronic devices.

Solvothermal Synthesis of CdS xSe 1- x Nanorods by Polymer Gel-Controlled Growth Strategy

Alloyed ternary CdS x Se 1- x nanorods have been synthesized by the thermal treatment of Cd 2+-dispersed polyethylene glycol 2 000 gel (PEG 2000) with ethylenediamine solution of sulfur and selenium in a sealed system at 180 °C for 24 h, in which the ratio of S to Se in the nanorods was controlled by adjusting the relative amounts of the starting materials. Based on the results of experiments, it is found that the CdS x Se 1- x nanorods were also synthesized with several sulfur sources by the method. X-ray diffraction (XRD) shows that the alloyed ternary CdS x Se 1- x nanorods are highly crystalline, and no other phase was observed in these nanorods.