As-synthesized ZnS Research Articles

ZnS QDs Stabilized Concurrently with Glutathione and L-cysteine for Highly Sensitive Determining Adriamycin Based on the Fluorescence Enhancement Mechanism.

In this work, a facile and fast aqueous-phase synthetic method is proposed to prepare water-soluble ZnS quantum dots stabilized simultaneously with glutathione and L-cysteine (ZnS QDs-GSH/L-Cys). As-synthesized ZnS QDs-GSH/L-Cys were monodispersed spherical nanocrystals with a mean diameter of 5.0 ± 0.7nm. Besides, the obtained ZnS QDs-GSH/L-Cys emitted more intensive blue fluorescence and exhibited an improved stability in aqueous solution compared with ZnS quantum dots merely stabilized with GSH (ZnS QDs-GSH). Interestingly, Adriamycin, a representative anticancer drug, was added into the solution of ZnS QDs-GSH/L-Cys, the blue fluorescence of ZnS QDs-GSH/L-Cys was greatly enhanced instead of being quenched, which indicated that ZnS QDs-GSH/L-Cys can be used as an enhanced-fluorescence nanoprobe for determining Adriamycin. The observed fluorescent enhancement could be attributed to the blocking of photoinduced electron transfer (PET) in ZnS QDs-GSH/L-Cys due to the electrostatic interaction between the -COO- groups on the surface of quantum dots and the -NH3+ groups in Adriamycin, followed by the coordination interaction among ZnS QDs-GSH/L-Cys and Adriamycin. The fluorescence intensity of ZnS QDs-GSH/L-Cys presented a good linear response with the concentration of Adriamycin ranging from 2.0 to 20µg•mL-1. The proposed fluorescent nanoprobe exhibited an excellent sensitivity with the LOD of 0.1µg•mL-1 and a good accuracy for detecting Adriamycin.

Binder-free cupric-ion containing zinc sulfide nanoplates-like structure for flexible energy storage devices

Researchers have been enthusiastic about developing high-performance electrode materials based on metal chalcogenides for energy storage applications. Herein, we developed cupric ion-containing zinc sulfide (ZnS:Cu) nanoplates by using a solvothermal approach. The as-synthesized ZnS:Cu nanoplates electrode was characterized and analyzed by using XRD, SEM, TEM, EDS, and XPS. The binder-free flexible ZnS:Cu nanoplates exhibited excellent specific capacitance of 545 F g−1 at a current density of 1 A g−1. The CV and GCD measurements revealed that the specific capacitance was mainly attributed to the Faradaic redox mechanism. Further, the binder-free flexible ZnS:Cu nanoplates electrode retained 87.4% along with excellent Coulombic efficiency (99%) after 5000 cycles. The binder-free flexible ZnS:Cu nanoplates exhibited excellent conductivity, specific capacitance, and stability which are beneficial in energy storage systems. These findings will also open new horizons amongst material scientists toward the new direction of electrode development.

Sonohydrothermal-assisted ZnS nanocrystals for improved structural, electronic, and optical properties: Experimental and ab initio methods

Herein, ZnS nanoparticles (NPs) with controlled size, crystal structure and effective optoelectronic properties were investigated via facile sonohydrothermal synthesis (SH) at 190 °C for up to 12 h. The average crystallite size of ZnS NPs using SH and hydrothermal (HT) were analysed through Debye–Scherrer equation from the X-ray diffraction (XRD). From current density–voltage (J–V) characteristics, the growth of nanoparticles by SH synthesis exhibits non-linear behaviour and higher current density than the HT method. The optical bandgap of as-synthesized ZnS nanoparticles of HT and SH synthesis were 3.60 and 3.61 eV, respectively. From the first-principles calculations using Tran–Blaha-modified Becke–Johnson potential, the bandgap is consistent with the experimental findings compared with the Perdew–Burke–Ernzerhof approximation. The obtained structural, electronic and optical properties revealed that SH synthesis is a potential alternative that may yield a possible route for developing new material applications in optoelectronics.

In situ topotactic fabrication of ZnS nanosheet by using ZnAl- layered double hydroxide template for enhanced tetracycline pollutant degradation activity

In this work, novel ZnS nanosheet was synthesized by using ZnAl-layered double hydroxide template for UV-light-driven photocatalytic degradation of tetracycline pollutant. The morphology, structure and UV light capacity of the obtained materials were characterized by XRD, SEM, TEM, HRTEM, EDS, FT-IR, UV–vis DRS, XPS, EIS Nyquist plots and PL spectrum, respectively. The results demonstrated that the as-synthesized ZnS nanosheet maintained layered structure and revealed the better photocatalytic activity than that of other materials toward tetracycline pollutant. The photocatalytic degradation efficiency of tetracycline pollutant was 85.73% under UV light irradiation using 500 W mercury lamp in 80 min, which was 1.53 times higher than that of pure ZnS microspheres. Besides, the as-prepared ZnS nanosheet exhibited higher stability and reusability after four runs. Eventually, a possible photodegradation mechanism was presented according to free radical trapping experiment. In addition, this work provided some references for the synthesis of related new photocatalytic materials.

ZnS microspheres-based photoconductor for UV light-sensing applications

The improvement in UV photoconductor device performance has been significantly realized by comprising the ZnS based nano/micro-structures. In the present work, a simple one-step hydrothermal technique has been implied to synthesize the ZnS based microspheres, and it has been utilized for the UV photoconductor device applications. FESEM analysis revealed that as-synthesized ZnS possesses the shape of a microsphere with nanosheets on its surface. The size of the microspheres and the thickness of the nanosheets is found to be ~1.5 (±0.3) µm and ~22 (±3) nm, respectively. The current-voltage (I-V) and current-time (I-T) measurements have been carried out under different UV light exposures, and various photoconductor performance parameters have been investigated systematically. The sensitivity and on/off ratio are estimated to be 0.21–0.35 and 1.21–1.35, respectively. However, responsivity and detectivity are found to be 2.74 × 10−4–8.94 × 10−5 A/W and 2.02 × 109–6.51 × 108 Jones, respectively. Improved responsivity and detectivity along with the faster rise/fall time (0.153/0.206 sec) are associated to higher active surface area and porosity that provided a higher number of active sites for charge carrier generations under UV light exposure.

Biotemplate Synthesis of Zinc Sulfide Spheres with High Photocatalytic Performance on Organic Dyes

Pure ZnS microspheres were generated via a biotemplate with the assistance of dispersant (methanol). The products were characterized by XRD, SEM, EDS and UV–Vis. By exploring the reaction constitutions, 150 °C and 9 h were found to be the optimal constitution for the synthesis of ZnS microspheres. A possible formation mechanism was proposed based on the experiment results. The roles of methanol and rutin in the forming of ZnS spheres were investigated. Rutin was found to be a key role as the biotemplate to control the diameter of ZnS particles, while methanol as the dispersant to prevent the agglomeration of the product. The as-synthesized pure ZnS microspheres via such a biotemplate method showed remarkable photocatalytic performance toward the degradation of methyl blue.

Tailoring the visible emissions in ZnS:Mn films for white light generation

Abstract This paper reports the effect of manganese incorporation on the structural, optical and luminescence properties of the as-deposited ZnS films prepared by RF magnetron sputtering process. Mn act as a nucleation centre for the growth of highly crystalline defect free ZnS films with mixed cubic and hexagonal phases. The +2 valence state of Mn ions in ZnS lattice is confirmed by the XPS analysis. An absorption band due to d-d transition of Mn2+ ions is visible in the absorption spectra of ZnS film with highest Mn doping concentration. ZnS:Mn films present an intense orange emission along with the host emissions of ZnS. Optimum Mn content for superior orange emission from ZnS:Mn films is found to be 3 wt %. Origin of orange photoluminescence emission due to the incorporation of Mn2+ in Zn2+ host lattice and its quenching due to cross-relaxation mechanism in the films with higher Mn doping concentration is discussed in detail. We report the possibility of one-step generation of white light emission from the as-synthesized ZnS:Mn films by the adequate tailoring of ZnS host emissions in the blue and green regions (445 nm and 530 nm respectively) and Mn related emission in the orange region (585 nm) employing only one excitation wavelength by suitably tuning the Mn doping concentrations. PL decay of the orange emission is monitored to explore the luminescence mechanism and lifetime of the emission.

Characterization, antimicrobial activity and photocatalytic degradation properties of pure and biosynthesized zinc sulfide nanoparticles using plant extracts

Pure and biosynthesized zinc sulfide nanoparticles (ZnS NPs) have been effectively synthesized by the simple chemical co-precipitation method by using various methanol plant extracts. The structural, morphological and chemical bonding of as-synthesized ZnS NPs was investigated with the assistance of X-ray diffraction, scanning electron microscopy and Fourier transmission infrared spectroscopy. Besides, optical properties were confirmed with the help of UV–Visible spectroscopy. The antimicrobial activity of pure and plant extracts capped ZnS NPs were scrutinized against different Gram-positive, Gram-negative bacteria and fungus culture using disk diffusion method. The obtained result clearly confirmed the as-synthesized ZnS NPs was potentially played as an antimicrobial agent against all tested microorganisms. Photocatalytic degradation of synthesized ZnS NPs also evaluated for methylene blue dye (MBD) and methyl orange dye (MOD) degradation under UV Light irradiation. From this investigation, photocatalytic degradation of eco-friendly synthesized ZnS NPs has high degradation to compare pure ZnS NPs. This enhanced degradation activity due to their particles size, structural property, narrowing optical band gap and antimicrobial properties. Here, we first time reported Syzygium aromaticum methanol extracts synthesized ZnS NPs for the MBD, MOD degradation with exhibited an excellent efficiency compared to other ZnS NPs.

Bias Voltage-Dependent Impedance Spectroscopy Analysis of Hydrothermally Synthesized ZnS Nanoparticles

In this report, bias voltage-dependent dielectric and electron transport properties of ZnS nanoparticles were discussed. ZnS nanoparticles were synthesized by introducing a modified hydrothermal process. The powder XRD pattern indicates the phase purity, and field emission scanning electron microscope image demonstrates the morphology of the synthesized sample. The optical band gap energy (Eg = 4.2 eV) from UV measurement explores semiconductor behavior of the synthesized material. The electrical properties were performed at room temperature using complex impedance spectroscopy (CIS) technique as a function of frequency (40 Hz-10 MHz) under different forward dc bias voltages (0-1 V). The CIS analysis demonstrates the contribution of bulk resistance in conduction mechanism and its dependency on forward dc bias voltages. The imaginary part of the impedance versus frequency curve exhibits the existence of relaxation peak which shifts with increasing dc forward bias voltages. The dc bias voltage-dependent ac and dc conductivity of the synthesized ZnS was studied on thin film structure. A possible hopping mechanism for electrical transport processes in the system was investigated. Finally, it is worth to mention that this analysis of bias voltage-dependent dielectric and transport properties of as-synthesized ZnS showed excellent properties for emerging energy applications.

Hydrothermally Synthesized Zinc Sulphide Microspheres for Solar Light-Driven Photocatalytic Properties

In this work, we reported the synthesis of zinc sulphide microspheres using the hydrothermal method. ZnS microspheres were synthesized using water, zinc acetate, thiourea and ammonia solution at 150°C for 6 h, 12 h, and 24 h. The as-synthesized ZnS powders were characterized by x-ray diffraction (XRD), field emission scanning electron microscopy (FESEM) and ultraviolet–visible (UV–Vis) spectroscopy. XRD indicates the cubic (major phase) as well as hexagonal (minor phase) crystalline phase with enhanced crystallinity increased gradually with more reaction time. UV–Vis spectra show the absorption peaks in the UV–Vis region for all the samples. The Tauc’s plot was used to calculate the band gap energy of ZnS samples, which are found to be 3.39 eV, 3.4 eV, and 3.42 eV for the samples synthesized at reaction times of 6 h, 12 h, and 24 h, respectively. FESEM images confirm the formation of microspheres as aggregates of spherical nanoparticles. The as-synthesized ZnS microspheres have been explored for solar light-induced photo-catalytic dye degradation of methylene blue (MB), and the results confirm that such microspheres exhibit effectual photocatalytic properties. Zinc sulphide microspheres have been synthesized hydrothermally at different reaction times (6 h, 12 h, and 24 h). The as-synthesized ZnS microspheres were successfully employed as photocatalyst for MB dye degradation. Due to high crystallinity, ZnS microspheres synthesized for 24 h show more efficient degradation potential than others.

Effects of Ni2+ concentration and vacuum annealing on structure, morphology and optical properties of Ni doped ZnS nanopowders synthesized by hydrothermal method

Ni doped ZnS nanopowders were synthesized by hydrothermal method. The as-synthesized ZnS nanopowders possessed zinc blende structure with the particle sizes of ∼20 nm, and they display a broad emission band from 400 nm to 700 nm centered at ∼540 nm. The influence of Ni2+ doping and vacuum annealing on the structure, morphology and optical properties was investigated systematically. The results revealed that the emission peaks are blue shifted with Ni2+ doping, and the emission peaks of 0.2, 0.4, 0.6, 0.8 and 1.0 mol% Ni2+ doped ZnS nanopowders are centered at ∼520, ∼ 510, 500, 490 and 470 nm, respectively. While, the zinc blende phase transformed to wurtzite phase when annealing at 600 °C or higher, and the annealed samples exhibited three emission peaks positioned at ∼490, ∼547 and ∼580 nm. The results indicated that the as prepared Ni2+-doped ZnS nanopowders have a potential application in LED as light conversion layer.

TEM characterization and cathodoluminescence study of mixed-phase ZnS nanostructures

In this work, we reported the synthesis of ZnS nanostructures featured a laminated morphology through a feasible chemical vapor deposition process. The microstructure and phase purity of as-synthesized ZnS nanostructures were examined by using an X-ray diffractometer (XRD) and high-resolution transmission electron microscope (TEM), and it was found that mixed cubic and hexagonal ZnS phases co-existed. The formation of cubic and hexagonal ZnS phases was derived from the numerous stacking faults generated inside the laminated ZnS nanostructures. Optical characterization of the ZnS nanostructures using cathodoluminescence spectrometer indicated that a broad emission band covering the wavelength of 400–600 nm in the visible range has been observed. Finally, the formation mechanism and related optical property of ZnS nanostructure were discussed based on TEM and CL results.

Morphological control of ZnS nanopowders by different capping molecules

Complex 3D architectures of ZnS microflowers have been successfully synthesized via a quick water-based precipitation synthesis method at moderate temperature (<100°C) using an inorganic capping agent K2S2O7. The synthesized samples were characterized by SEM, XRD, FTIR and BET analysis. The as-synthesized ZnS microflowers are composed of numerous nanowires and has a cubic structure. Surface area is 42m2·g−1 and the pore diameter is 3.7nm. Comparison with equivalent synthesis with an organic capping agent (PVP) was performed.

Two-photon absorption induced photoluminescence from ZnS nanowires

In this work, the ZnS nanowires was synthesized on Au-coated Si substrate by a vapor phase transport (VPT) method. The morphology and structure of the as-synthesized ZnS nanowires were studied through scanning electron microscope (SEM), transmission electron microscope (TEM) and X-ray diffraction (XRD). Under excitation of the femtosecond (fs) pulsed laser at 650 nm, a strong ultraviolet (UV) emission centered at 343 nm was observed. The peak position and the relationship between the emission intensity and the excitation intensity demonstrated that the UV photoluminescence (PL) be induced by the two-photon absorption (2PA) process. The characteristics and the generation process of the above nonlinear optical phenomena were investigated in detail.

Zinc thiosemicarbazone complexes: Single source precursors for alkylamine capped ZnS nanoparticles

We report the syntheses of Zn (II) thiosemicarbazone complexes, ZnCl2(benztsczH)2 (1), Zn(benztscz)2 (2) and Zn(4-Cl-benztscz)2 (3), where (benztscz=benzaldehyde thiosemicarbazone (L1) and 4-Cl-benztscz=4-Chloro benzaldehyde thiosemicarbazone (L2)). The complexes were used as single source precursors for the fabrication of ZnS nanoparticles via thermal decomposition at 230°C using oleylamine as coordinating solvent. The single crystal X-ray structure of complex (1) was also elucidated. The powder X-ray diffraction (p-XRD) analysis confirmed the cubic and crystalline nature of the as-synthesized ZnS nanoparticles. Transmission electron microscope (TEM) analysis showed formation of spherical nanoparticles with sizes between 5 and 10nm for oleylamine capped ZnS nanoparticles. Optical absorption analysis showed ZnS displaying size quantum effect due to the small size of the as-synthesized particles. The value of absorption band gap determined varies in the range of 3.7–3.9eV. Room temperature photoluminescence (PL) spectrum of ZnS nanoparticles exhibit a blue emission peak at ∼387nm.

Facile synthesis of ZnS nanorods in PEG and their spectral performance

Green and one-step synthesis of ZnS nanorods through the interaction of zinc nitrate hexahydrate and S powder in PEG400 was studied. Orthogonal experiments were conducted to study the influence of the experimental conditions including the molar ratio of sulfur (nS) and zinc nitrate hexahydrate (nZn), the heating time and the molecular weight of PEG (200, 400, 600) on the nature and morphology of the products. The results show that the zinc/sulfur molar ratio determines the composition of the products. When the zinc/sulfur molar ratio is 2 mmol:1 mmol with temperature of 160 °C and reaction time of 120 min, homogeneous ZnS nanorods, with diameters and lengths of about 64 nm–110 nm and 110–1100 nm respectively are obtained. The structure, morphology, size, stability and optical properties of the products were investigated by x-ray diffraction (XRD), x-ray photoelectron spectroscopy (XPS), Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), ultraviolet-visible (UV–vis) absorption and photoluminescence. The band-gap value estimated from the UV–vis absorption spectrum is 4.15 eV. The as-synthesized ZnS shows blue (469 nm) and green (506 nm) broad emission bands when they are excited by visible light (439 nm). Possible formation mechanism is also discussed.

ZnS–ZnO nanocomposites: synthesis, characterization and enhanced photocatatlytic performance

ZnS–ZnO nanocomposites (NCs) were successfully synthesized via thermal treatment of as-synthesized ZnS nanostructured spheres (NSs). By applying multiple characterization technology, such as XRD, FESEM, EDS and UV–Vis, the obtained samples were fully characterized. After modification, the light-absorption performance of ZnS NSs to visible light was significantly enhanced. The band gap of ZnS–ZnO NCs was estimated to be 2.7 eV. The photocatalytic test indicated that ZnS–ZnO NCs exhibited enhanced photocatalytic activity in contrast to the pristine ZnS due to the effective charge separation. A photocatalytic mechanism was proposed to illustrate the photocatalytic reduction process. The formation mechanism of ZnS NSs and ZnS–ZnO NCs was also proposed in detail.

Anionic precursor-mediated morphology-controlled synthesis of ZnS nanostructures: Morphology-dependent tunable photoluminescence in the visible region and pulsed laser-induced efficient reduction of Cr(VI)

Developing a green and convenient synthesis protocol for modification of the morphology of ZnS nanostructures is of great interest but remains a challenge. Herein, a strategy is proposed for tuning the morphology of ZnS nanostructures using different anionic precursors without addition of any organic surfactants or templates. The role of anionic precursors in determining the morphologies is investigated, and a possible growth mechanism involving oriented aggregation and the Ostwald ripening process is proposed. The as-synthesized ZnS nanostructures exhibit outstanding tunable photoluminescence in the visible region depending on the morphology and excitation wavelength. Additionally, the photocatalytic reduction of aqueous Cr(VI) under pulsed irradiation was studied using ZnS catalysts of various nanostructure morphologies in order to study the influence of morphology on the photocatalytic activity of ZnS nanostructures. The analysis revealed that rice grain-shaped ZnS nanostructures exhibit more efficient photocatalytic Cr(VI) reduction compared to other nanostructures. This work also investigated the dependence of the rate of Cr(VI) reduction on the pulsed laser power, pH, and Cr (VI) concentration. The results presented herein should provide a new approach for designing ZnS nanostructures with different morphologies for application in light emitting diodes (LEDs) and water purification systems.

Chemical synthesis, compositional, morphological, structural, optical and magnetic properties of Zn1−xDyxS nanoparticles

Zn1−xDyxS (x=0, 0.02 and 0.04) nanoparticles (NPs) were synthesized by chemical refluxing technique at 100°C. The prepared samples were analyzed by studying their compositional, morphological, structural, optical and magnetic properties. EDS analysis confirmed the presence of zinc, dysprosium and sulfur in the samples in near stoichiometric ratio. The X-ray diffraction patterns do not show any Dy related peaks for the as-synthesized ZnS nanoparticles. The average diameter of the particles confirmed by TEM studies, was in the range 2–4nm. Raman studies revealed that all the samples are single phase and exhibit cubic structure. From DRS studies, the band-gap was found to be in the range of 3.85–3.70eV. All the doped ZnS nanoparticles exhibit ferromagnetic behavior with the Curie temperature higher than room temperature and the magnetic properties of doped ZnS nanoparticles depend on the concentration of Dy ions.

Hydrothermal/Solvothermal Synthesis and Photocatalytic Performance of ZnS Microspheres

ZnS microspheres were synthesized via hydrothermal/solvothermal method using Zn(Ac)2·2H2O and CH4N2S as reactants. ZnS was characterized by XRD, SEM and UV-Vis diffuse reflectance spectrum. The results showed that as-synthesized ZnS microspheres had zinc blende crystalline structure which was self-assembled by small ZnS nanoparticles. As for the photocatalytic degradation of phenol aqueous solution, ZnS microspheres synthesized in (CH2OH)2-H2O system revealed much better photocatalytic activity than that of ZnS synthesized in other solvent systems, and it kept high activity after cycling degradation for 3 times. The enhanced photocatalytic performance of ZnS microspheres could be attributed to the cooperation effect of the following three aspects: the smaller band gap (3.39 eV) being conducive to the absorption of photons, the more complete crystal structure to increase the number of active molecules, and larger specific surface area (19.4 m/g) being in favor of sufficient contacting between the reaction solution, and the catalyst. The intermediate products were oxalic acid, maleic acid and very little hydroquinone in photocatalytic degradation of phenol by ZnS microspheres.