CdS Semiconductor Nanoparticles Research Articles

Research of CdS/L-cystein colloid solutions using the method of mathematical planning

In the work, the additive effect of the content of crystal-forming ions Сd2+ and S2- and the stabilizer L-Cys using the method of mathematical planning of the experiment on the process of formation of CdS/L-Cys nanoparticles in potentially oxidizing conditions (without deaeration of precursor solutions) and the optical properties of colloidal solutions were investigated. obtained under conditions of pH = 7 and temperature of 220C. By statistical processing of the results, equations were obtained and diagrams of concentration dependences of the wavelength of the optical absorption edge of colloidal solutions of CdS semiconductor nanoparticles in the Сd2+ – L-Cys – S2- system were constructed.

Enhanced nonlinear optical properties of reduced graphene oxide modified by Mn-doped semiconductor CdS nanoparticles as photonic materials

Graphene has broad prospects for application in photonic devices. However, its zero-band gap limits its nonlinear optical (NLO) properties, and thus, its application. In this study, we synthesized reduced graphene oxide modified by Mn-doped semiconductor CdS nanoparticles (RGO/CdS:Mn) via a solvothermal method to study the development of NLO properties of graphene. The structures, morphologies and basic physical properties of RGO, CdS, RGO/CdS, and RGO/CdS:Mn were characterized. The third-order optical nonlinearities were tested by the Z-scan technique using a mode-locked Nd:YAG laser operating at 532 nm with a 30 ps pulse width. The results showed that the nonlinear susceptibility and saturation absorption of RGO/CdS:Mn were 15.3 and 26 times higher than those of RGO, respectively. The mechanism of the enhancement was analyzed based on the charge transfer between and within the components, and Mn doping produced trapping effect. The significantly improved optical nonlinearity of RGO/CdS:Mn lays a foundation for its applications in photonic devices.

Photovoltaic properties of cd-based ionic liquid crystals with semiconductor nanoparticles

The photovoltaic effect in pure cadmium-alkanoate matrices and in their nanocomposites with semiconductor CdS nanoparticles (NPs) was revealed and investigated. The main mechanism of the phenomenon is the Dember effect, in which the internal field of non-equilibrium charge carriers is formed due to a significant difference in the mobility of positive and negative charges. NPs synthesized in the matrix lead to a significant increase in the concentration of the photo-generated electrons and thus to an increase in the photo-electro-driving force in the material. The magnitude and kinetics of the photocurrent for nanocomposites substantially depend on the content of only a small amount (2 − 4 mol. %) of NPs.

Structure, optical and photoluminescent properties of hybrid polymer nanocomposites on the base PP+CdS/ZnS

In this work, PP+CdS/ZnS transparent hybrid polymer nanocomposites were synthesized and studied. The nanocomposites were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive (EDS), and UV-spectroscopy analysis. It was found that the bandgap of PP+1%CdS/ZnS; PP+3%CdS/ZnS, and PP+5%CdS/ZnS; PP+10%CdS/ZnS nanocomposites is 5.2 eV, 5.1 eV, 4.6 eV, respectively. SEM analysis showed that the ZnS and CdS nanoparticles are evenly distributed in the polymer matrix. Furthermore, the average size of nanoparticles in the PP+3%CdS/ZnS, PP+5%CdS/ZnS nanocomposite is 40-54 nm, 29-56 nm, respectively. Photoluminescence properties of hybrid PP+CdS/ZnS nanocomposites were also investigated. It was established that introduction of ZnS and CdS semiconductor nanoparticles into the polypropylene matrix leads to expanding the region of the spectral sensitivity of hybrid nanocomposites. The photosensitivity of PP+CdS/ZnS nanocomposite films was also investigated.

Photosensitive hybrid polymer nanocomposites on the base PVDF+CdS/ZnS for solar cells application

ABSTRACT Combined hybrid nanocomposites based on PVDF+CdS/ZnS were developed and studied. The structure of nanocomposites was characterized by XRD, SEM, EDS, UV- spectroscopic techniques. XRD analysis shows that the incorporation of CdS and ZnS semiconductor nanoparticles leads to a decrease in the fraction of the α-phase and an increase in the β-phase of the polymer. It was determined that the bandgap of the nanocomposite based on PVDF+1%CdS/ZnS, PVDF+3%CdS/ZnS, PVDF+5%CdS/ZnS and PVDF+10%CdS/ZnS is 5.3 eV, 5.0 eV, 4.3 eV and 3.1 eV, respectively. The photoluminescence properties of the polymer nanocomposites were also examined. It was established that for these nanocomposites, the introduction of the CdS/ZnS nanoparticles into the polymer matrix leads to expanding of the spectral-sensitive region of the PL spectrum of the nanocomposites. It was shown that combine hybrid nanocomposites on the base of PVDF+CdS/ZnS emit the light at the wide-wavelength-range. According to this feature, it is possible to use these nanocomposites in various fields of optoelectronics as the active elements of solar batteries, cells, displays, converters, etc. The photosensitivity of the PVDF+CdS/ZnS films was discovered. It gives the possibility to use these materials as thermoplastic photoresistors.

Photoconversion of glucose to glucuronic acid over plasmonic M-CdS/MOR (M= Ag, Au) nanocomposites

Photocatalysts based on silver or gold metallic and CdS semiconductor nanoparticles embedded on a mordenite matrix (M-CdS/MOR), was successfully synthesized and tested to obtain glucuronic acid by photoconversion of glucose. The M-CdS/MOR photocatalyst exhibited a synergistic interaction between the plasmonic behavior from metallic nanoparticles and the photoactive properties of semiconductor nanoparticles, which leads to the photoconversion of the glucose (38% in 60 min). The reaction mechanisms are presented and discussed.

Photoluminescence emission from nanostructured porous preparations of CdS-ZnTiO3 assembled nanoparticles.

This study reports the structural and optical properties of CdS/ZnTiO3 nanocomposites prepared using a chemical bath and different titanate concentrations. Commercial ZnTiO3 nanoparticles were introduced into a chemical bath that had been used to produce CdS semiconductor nanoparticles (NPs). Here, the growing CdS crystallites precipitated onto the suspended zinc titanate NPs. X-ray diffraction patterns revealed that samples of CdS/ZnTiO3 nanopowders were made of cubic ZnTiO3 and hexagonal CdS wurtzite. The morphology of the particles was studied using transmission electron microscopy and scanning electron microscopy images. These images demonstrated the different characteristics of the CdS/ZnTiO3 nanocomposites and their dependence on titanate concentration when placed into the CdS-growing solution. Photoluminescence spectra showed three main emission bands for the electron transitions in the CdS/ZnTiO3 composite. This composite produced three photoluminescence bands, the intensities of which depended on composite shape, which in turn depended on the relative concentrations of CdS and ZnTiO3 .

Simultaneous enhancements of light-harvesting and charge transfer in UiO-67/CdS/rGO composites toward ofloxacin photo-degradation

Antibiotics residues in aquatic environments has aroused great public concern since they cannot be effectively removed by conventional biological degradation. Sunlight-driven photo-degradation has been recognized as one of most efficient approach for the antibiotics removal. Herein, we proposed a novel strategy of simultaneous light-harvesting and electron-relay-penetration for the photocatalytic degradation of target antibiotics of ofloxacin (OFL). By incorporating visible-light responded semiconductor CdS nanoparticles into MOF and encapsulating by excellent conductor rGO thin sheets, a series of mesoporous composites of UiO-67/CdS/rGO-x were developed. As a result, the obtained UiO-67/CdS/rGO-1 showed the highest OFL degradation efficiency of 93.4% within 30 min for a 10 ppm OFL solution under the simulated sunlight, in which the turnover frequency (TOF) of 5.44 × 10−3 g(OFL) min−1 g(Cat.)−1 showed an order of magnitude increase over the relevant works. The mechanism study revealed the superoxide radicals O2− and photo-generated hole h+ were the excitons for the photocatalytic oxidation. The equalized Fermi level of UiO-67/CdS heterojunctions was formed to facilitate the electrons relaying, spilling-over, and penetrating through wrapped thin-layered rGO; meanwhile, the selective adsorption of OFL synergistically enhanced the photocatalysis, and hence provided a promising strategy for environmental remediation.

Photoelectrochemical performance of dye and semiconductor sensitization on 1-D hollow hexagonal ZnO rods: A comparative study

One-dimensional hollow hexagonal ZnO rods (1-D HHZRs) were grown onto the SnO2: F (FTO) coated glass substrates by using two-step deposition techniques. Initially, the ZnO seed layer was coated onto the FTO which was followed by hydrothermal route in order to grow 1-D HHZRs. These 1-D HHZRs were decorated with Eosin-Y dye and CdS semiconductor nanoparticles (NPs) by using a chemical routes like dip coating and successive ionic layer absorption reaction (SILAR) technique, respectively to improve its photoelectrochemical (PEC) performance. The structural, morphological, optical and electrochemical characterizations of the thin films were analyzed by various sophisticated instruments. X-ray diffraction (XRD) pattern corroborated the phase formation of ZnO and CdS with the hexagonal and cubic crystal structure, respectively. 1-D HHZRs films were obtained by scanning electron microscopy (SEM) with rod diameter of about 1.47 μm. Furthermore, SEM image clearly showed the CdS NPs covered 1-D HHZRs. The direct optical bandgap energy of the samples were estimated to be 3.28, 3.24 and 3.03 eV. CdS NPs-sensitized 1-D HHZRs samples showed hydrophilic nature for water contact angle, which is advantageous for the better improvement in the PEC performance as compared with pristine and dye-sensitized 1-D HHZRs.

Random lasing characteristics in dye-doped semiconductor CdS nanoparticles**Supported by the Doctoral Science Research Start-up Funding of GuiZhou Normal University No. 11904-0514162.

A new strategy to obtain random lasing from semiconductor CdS nanoparticles is presented. A device is prepared with dye (DCM) solution containing CdS NPs. Good lasing behavior is reached and the multiple light scattering process is responsible for lasing generation. We also manage to show that the lasing modes and output intensity exhibit angular dependence. The result indicates that CdS nanoparticles can be used as ideal microlaser material in future semiconductor laser devices.

Photoelectrochemical detection of enzymatically generated CdS nanoparticles: Application to development of immunoassay.

We report an innovative photoelectrochemical process (PEC) based on graphite electrode modified with electroactive polyvinylpyridine bearing osmium complex (Os-PVP). The system relies on the in situ enzymatic generation of CdS quantum dots (QDs). Alkaline phosphatase (ALP) catalyzes the hydrolisis of sodium thiophosphate (TP) to hydrogen sulfide (H2S) which in the presence Cd(2+) ions yields CdS semiconductor nanoparticles (SNPs). Irradiation of SNPs with the standard laboratory UV-illuminator (wavelength of 365 nm) results in photooxidation of 1-thioglycerol (TG) mediated by Os-PVP complex on the surface of graphite electrode at applied potential of 0.31 V vs. Ag/AgCl. A novel immunoassay based on specific enzyme linked immunosorbent assay (ELISA) combined with the PEC methodology was developed. Having selected the affinity interaction between bovine serum albumine (BSA) with anti-BSA antibody (AB) as a model system, we built the PEC immunoassay for AB. The new assay displays a linear range up to 20 ngmL(-1) and a detection limit (DL) of 2 ngmL(-1) (S/N=3) which is lower 5 times that of the traditional chromogenic ELISA test employing p-nitro-phenyl phosphate (pNPP).

Application of photocatalytic cadmium sulfide nanoparticles to detection of enzymatic activities of glucose oxidase and glutathione reductase using oxidation of 3,3′,5,5′-tetramethylbenzidine

It was found out that semiconductor CdS nanoparticles (NPs) are able to catalyze photooxidation of the well known chromogenic enzymatic substrate 3,3′,5,5′-tetramethylbenzidine (TMB) by oxygen. The photocatalytical oxidation of TMB does not require hydrogen peroxide and its rate is directly proportional to the quantity of CdS NPs produced in situ through the interaction of Cd2+ and S2− ions in an aqueous medium. This phenomenon was applied to development of colorimetric sensitive assays for glucose oxidase and glutathione reductase based on enzymatic generation of CdS NPs acting as light-powered catalysts. Sensitivity of the developed chromogenic assays was of the same order of magnitude or even better than that of relevant fluorogenic assays. The present approach opens the possibility for the design of simple and sensitive colorimetric assays for a number of enzymes using inexpensive and available TMB as a universal chromogenic compound.

Photocatalytic applications with CdS • block copolymer/exfoliated graphene nanoensembles: hydrogen generation and degradation of Rhodamine B

Amphiphilic block copolymer poly(isoprene-b-acrylic acid) (PI-b-PAA) was used to stabilize exfoliated graphene in water, allowing the immobilization of semiconductor CdS nanoparticles forming CdS • PI-b-PAA/graphene. Characterization using high-resolution transmission electron microscopy and energy-dispersive x-ray spectroscopy proved the success of the preparation method and revealed the presence of spherical CdS. Moreover, UV–Vis and photoluminescence assays suggested that electronic interactions within CdS • PI-b-PAA/graphene exist as evidenced by the significant quenching of the characteristic emission of CdS by exfoliated graphene. Photoillumination of CdS • PI-b-PAA/graphene, in the presence of ammonium formate as a quencher for the photogenerated holes, resulted in the generation of hydrogen by water splitting, monitored by the reduction of 4-nitroaniline to benzene-1,4-diamine (>80 ± 4% at 20 min; 100% at 24 min), much faster and more efficient compared to when reference CdS • PI-b-PAA was used as the photocatalyst (<30 ± 3% at 20 min; 100% at 240 min). Moreover, Rhodamine B was photocatalytically degraded by CdS • PI-b-PAA/graphene, with fast kinetics under visible light illumination in the presence of air. The enhancement of both photocatalytic processes by CdS • PI-b-PAA/graphene was rationalized in terms of effective separation of holes and electrons, contrary to reference CdS • PI-b-PAA, in which rapid recombination of the hole–electron pair is inevitable due to the absence of exfoliated graphene as a suitable electron acceptor.

Effect of silver doping on TiO2, CdS, and ZnS nanoparticles for the photocatalytic degradation of metronidazole under visible light

Continuously increasing consumption of antibiotics in health care has led to increased concentration of these compounds in surface water through wastewater treatment systems, which in turn cause adverse effects on the aquatic ecosystems of the receiving water bodies because of the intrinsic biological activity of these compounds. However, there are limited efforts on the remediation of water pollution because of antibiotics using an effective and clean technology. In this study, the photocatalytic activity of TiO2, CdS, and ZnS semiconductor nanoparticles was employed to degrade the metronidazole antibiotic using visible light irradiation. These particles were also modified by silver doping to improve their degradation efficiency. Note that doping with silver greatly enhanced the degradation efficiency of these nanoparticles. The specific concentration of silver dopants necessary to achieve the maximum degradation efficiency was also identified for TiO2, CdS, and ZnS nanoparticles. The basic mechanism of doping and the photocatalytic processes were explored in detail. A kinetic study of the degradation reaction fits first order kinetics well for all three cases. The reusability and stability of these photocatalysts was confirmed by cyclic degradation tests.

Development of a novel enzyme-CdS nanoparticle hybrid system for the oxidation of NADH to NAD+

Inorganic semiconductor CdS nanoparticles (NPs) incorporating NADH dehydrogenase (diaphorase: DA) were successfully synthesized using a water-in-oil microemulsion method. The X-ray diffraction pattern of the enzyme-CdS NPs was assigned to a cubic structure CdS phase. The catalytic effect of enzyme-CdS NPs hybrid systems on the oxidation of dihydronicotinamide adenine dinucleotide (NADH) to nicotinamid adenine dinucleotide (NAD+) was investigated. Enzyme-CdS NPs incorporating DA and ferrocene-modified polyethylenimine (Fc-PEI) (1:0.2, w/w) exhibited a significantly increased rate of NADH oxidation under illumination compared with pure CdS NPs. The redox mediator Fc-PEI acted to transfer electrons between the valence band of the CdS NPs and the flavin-bound enzyme during the oxidation reaction. Switchable oxidation of NADH in a colloidal solution of the enzyme-CdS NPs was induced with respect to the dark/light cycle. The catalytic properties of the present CdS NPs activated with an enzyme towards NADH oxidation might have future importance in biochemistry and medical applications.

Synthesis and characterization of functionalized dithiocarbamates: New single-source precursors for CdS

Novel single-molecular precursors for CdS are prepared by reacting functionalized secondary amine and CS2 with cadmium acetate dihydrate. All these precursors are characterized by elemental analysis, infrared spectroscopy and solid-state 13C NMR. CdS semiconductor nanoparticles are synthesized using these precursors by a single-step solvothermal method with ethylenediamine at 117°C. The synthesized semiconductor nanoparticles are investigated by infra-red spectroscopy, powder X-ray diffraction analysis, energy-dispersive X-ray spectroscopy analysis, scanning electron microscopy, field emission scanning electron microscopy, transmission electron microscopy, high resolution transmission microscopy, selected area electron diffraction analysis and Raman spectroscopy. The synthesized CdS are hexagonal (zinc wurtzite) crystalline material, which are indicative of the reduction of particles. Comparison with the CdS and the mixture of CdS/CdS⋅0.5gl revealed that the CdS/CdS⋅0.5gl exhibited a well crystalline structure.

Optical properties of the hybrid nanocomposites consisting of poly-n-phenylvinylene and cadmium sulfide

Thin-film hybrid nanocomposites based on poly-n-phenylvinylene with various contents of the CdS semiconductor nanoparticles are obtained using the pyrolytic polymerization of dichloro-n-xylene from the gas phase and the simultaneous sedimentation of the CdS vapor with the subsequent thermal processing of the precursor. The structure of the nanocomposite is studied, and the optical properties of the materials are analyzed. It is demonstrated that a variation in the concentration of the inorganic component in the polymer matrix leads to a variation in the maximum fluorescence wavelength and optical band gap. The material parameters (degree of conjugation of poly-n-phenylvinylene, band gap, Huang-Rhys factor, Stokes shift, and vibronic energy of molecules) are determined.

Fabrication and characterization of II–VI semiconductor nanoparticles decorated electrospun polyacrylonitrile nanofibers

Semiconductor nanoparticles incorporated highly aligned electrospun polyacrylonitrile (PAN) composite nanofibers were obtained via a simple, scalable and low-cost dip coating technique at room temperature. The resultant PAN nanofibers exhibited good incorporation of CdS, ZnS and CoS semiconductor nanoparticles. The detailed characterizations of these composite nanofibers were investigated. The incorporation of semiconductor nanoparticles on the surfaces of PAN nanofibers were confirmed by scanning electron microscopy (SEM), energy dispersive X-ray (EDX) spectroscopy and X-ray diffraction analysis. The current–voltage (I–V) characteristics revealed that the electrical conductivity of these composite nanofibers were higher than that of the pristine PAN nanofibers. Overall, the feasibility of obtaining uniformly dispersed semiconductor nanoparticles on PAN nanofibers can be utilized for the realization of various nanotechnological device applications.

Sensing behavior of CdS nanoparticles to SO2, H2S and NH3 at room temperature

The sensors based on the semiconductor CdS nanoparticles were fabricated in spray technology. The properties of the sensors response to SO2, H2S, NH3, NO2, water vapor and some organic solvent vapors were studied systematically. The sensors exhibited a good response to SO2, H2S and NH3 at room temperature. The sensor based on CdS prepared with Na2S at 353K displayed a linear response to NH3 from 0.3 to 6.0% and to SO2 from 0.5 to 1.7%. The sensor based on CdS prepared with H2S at 353K displayed a linear response to NH3 from 0.08 to 1.1% and to SO2 from 0.25 to 1.5%. All the sensor response and recovery times were less than 54s and 70s respectively. Temperature and operating voltage significantly affected the response of the sensor.

Photoinduced interactions between coumarin 151 and colloidal CdS nanoparticles in aqueous suspension

The photophysical features of 7-amino-4-trifluoromethylcoumarin (C151) in colloidal suspension that contains CdS semiconductor nanoparticles were investigated by using molecular UV–Vis absorption, steady-state and time-resolved fluorescence, and electron spin resonance (ESR) spectroscopy techniques. For this aim, the fluorescence intensity quenching of C151 molecules in colloidal aqueous solution containing colloidal CdS nanoparticles were examined. It was found that electrostatic interactions of C151 molecules at the ground state with CdS nanoparticles cause adsorption of certain amount of dye molecules onto colloidal CdS nanoparticles. After that, molecular excitation of C151 in the colloidal suspension leads to the formation of singlet excited state of C151 molecules and then adsorbed C151 molecules, at the singlet excited state, onto surfaces of CdS nanoparticles cause charge injection process. Therefore, the apparent association constants (Kapp), occurring between C151 molecules and colloidal CdS nanoparticles, and charge injection rate constants (ket) were calculated and compared with the values reported in the literature.