Undoped ZnS Research Articles

Structural and Optical Properties of Nickel-Doped Zinc Sulfide.

In this study, undoped and Ni-doped ZnS nanoparticles were fabricated using a hydrothermal method to explore their structural, optical, and surface properties. X-ray diffraction (XRD) analysis confirmed the cubic crystal structure of ZnS, with the successful incorporation of Ni ions at various doping levels (2%, 4%, 6%, and 8%) without disrupting the overall lattice configuration. The average particle size for undoped ZnS was found to be 5.27 nm, while the Ni-doped samples exhibited sizes ranging from 5.45 nm to 5.83 nm, with the largest size observed at 6% Ni doping before a reduction at higher concentrations. Fourier-transform infrared (FTIR) spectroscopy identified characteristic Zn-S vibrational bands, with shifts indicating successful Ni incorporation into the ZnS lattice. UV-visible spectroscopy revealed a decrease in the optical band gap from 3.72 eV for undoped ZnS to 3.54 eV for 6% Ni-doped ZnS, demonstrating tunable optical properties due to Ni doping, which could enhance photocatalytic performance under visible light. Scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDX) analyses confirmed the uniform distribution of Ni within the ZnS matrix, while X-ray photoelectron spectroscopy (XPS) provided further confirmation of the chemical states of the elements. Ni doping of ZnS nanoparticles alters the surface area and pore structure, optimizing the material's textural properties for enhanced performance. These findings suggest that Ni-doped ZnS nanoparticles offer promising potential for applications in photocatalysis, optoelectronics, and other fields requiring specific band gap tuning and particle size control.

Enhanced optical third-harmonic generation in phase-engineered nanostructured Zn1−x Cd x S thin films for optoelectronic device applications

A polycrystalline nanostructured thin film of zinc cadmium sulfide was meticulously fabricated on a glass substrate using the thermal evaporation method physical vapor deposition within a vacuum chamber. Different doping concentrations were introduced by varying the cadmium (Cd) content, resulting in Zn1-x Cd x S films with Cd concentrations ranging from x = 0.00–0.20 wt %. The impact of Cd doping on the third-order nonlinear optical (TONLO) properties of these films was thoroughly studied using the Z-scan method, employing a diode-pumped solid-state continuous-wave laser. To gain insight into the structural characteristics, the Zn1-x Cd x S thin films underwent analysis through x-ray diffraction. Optical studies confirmed the tunability of the optical band gap (Eg) in the Zn1-x Cd x S films, ranging from 3.88 eV for undoped ZnS to 2.80 eV for the film fabricated with 20 wt. % of Cd-content. This significant reduction in ‘Eg’ renders the films highly suitable for use as absorbing layers in applications such as solar cells and optoelectronics. Surface morphology analysis, performed via field emission scanning electron microscopy, revealed noticeable alterations with increased Cd doping. Significantly, the doped films exhibited a substantial redshift in the band edge and an increase in transmittance within the visible and near-infrared regions. The investigation of TONLO properties, including the nonlinear absorption coefficient (β), nonlinear refractive index (n 2) and susceptibility χ(3), yielded values ranging from 3.15 × 10−3 to 8.16 × 10−3 (cm W−1), 1.65 × 10−8 to 7.45 x 10–8 (cm2 W−1), and 3.12 × 10−5 to 7.86 × 10−5 (esu), respectively. These results indicate the presence of self-defocusing nonlinearity in the films. Overall, the outcomes underscore the potential of Cd-doped ZnS nanostructures in modifying surface morphology and enhancing NLO characteristics. Zn1-x Cd x S thin films exhibit promise for applications in nonlinear optical devices, as evidenced by these encouraging findings.

Colloidal one-pot synthesis and characterization of Glycine capped Al(x) doped ZnS QDs for efficient UV light assisted photo-degradation of Stilbene 420 dye

In thisstudy, successful synthesis and characterization of undoped and Al-doped ZnS quantum dots (QDs) capped with bio-friendly glycine (ZnSAl/Gly) are described. The synthesis is accomplished through a one-pot colloidal co-precipitation process, followed by the characterization of QDs using various analytical techniques.X-ray diffraction (XRD) and high-resolution transmission electron microscopy (HR-TEM) showed the formation of cubic-faced ZnS QDs, with the crystal size decreasing as the amount of Al doping increased. A ZnS phase layer on the QDs surface was also demonstrated by Fourier-transform infrared spectroscopy (FTIR) measurements. Field emission scanning electron microscopy with energy dispersive X-ray spectroscopy (FESEM-EDS) analysis was employed to examine the stoichiometry and shape of the synthesized QDs. Thermogravimetric analysis (TGA) showed a remarkable stability of Al-doped ZnS QDs over an extended period, enhancing their potential for a variety of applications. Measurements of the absorption band edge in the UV–Visible range demonstrated that Al ions were successfully incorporated into the ZnS lattice, causing a substantial red shift. This change, which caused the energy band gap to rise from 3.2 eV (ZnS/Gly) to 4.42 eV (ZnSAl1%/Gly), was attributed to the size confinement effect. The degradation of the Stilbene-420 dye under UV irradiation served as a test for the photodegradation capability of the synthesized QDs. The photodegradation efficiency of Al doping ranged from 60 % to 92 %, showing the induction of a significant number of crystalline structures with rising Al concentration. The Al-doped ZnS/Gly QDs are highly catalytic and photoactive, and they show great promise in the field of photoluminescence, medical and biological areas. Their potential for use as effective catalysts in waste water treatment methods is also remarkable.

ZnS and Fe-doped ZnS photocatalysts for improved visible light driven photocatalytic degradation of methylene blue

In the current research un-doped and Fe-doped ZnS nanocrystals (Zn1−xFexS (x = 0.0–0.08) were synthesized by wet chemical method. The synthesized nanocrystals were characterized by X-ray diffraction measurements, scanning electron microscopy, Fourier transformed infrared microscopy, UV–Vis, and Photoluminescence spectrometer. The particle size at different doping concentration was found to be 2.80, 2.77, 2.59 and 1.68 nm and the size of un-doped ZnS is found to be 3.76 nm. Photocatalytic performance of un-doped ZnS and Fe-doped ZnS nanocrystals was evaluated by de-colorization of methyl blue under UV light. It was observed that Fe-doped ZnS decolorized dye solution at fast rate as compared to un-doped ZnS. The maximum degradation (94 %) was observed when Zn0.92Fe0.08S was used as photocatalyst.

Suppression of ferromagnetism due to N co-doping in Cr(II)-doped ZnS nanowires and their optical properties: Insights from density-functional calculations

Spin-related optical properties will be the main basis for future information technology, but they require microscopic ferromagnetic and anti-ferromagnetic couplings between the d-states of the transition metal ions or magnetic interaction between excitons and magnetic ions, all of which remain unclear in these diluted magnetic semiconductors.In this work, we studied the influence of Cr doping and co-doping of Cr with N on the electronic, optical, and magnetic properties of ZnS nanowires using spin-polarized density functional theory. According to our findings, Cr(II) doping induces a half-metallic state with a magnetic moment of 4 μB per Cr(II) ion. The ferromagnetic behaviors and high Curie temperature in undoped Cr(II)-doped ZnS nanowires were suppressed due to the hole-carriers introduced by N co-doping. The band-coupling model was used to explain ferromagnetic (FM) stability in Cr(II)-doped nanowires with and without N co-doping. The optical properties of undoped ZnS nanowire, doped, and co-doped wires have been computed, and it is found that the bandgap (3.49 eV) exhibits a red shift upon Cr(II) doping, with the energy bandgap falling from 3.49 to 3.20 eV, and the bandgap being further decreased to 3.05 eV upon N co-doping. Compared with pure ZnS nanowires, mono- and co-doped nanowires have a higher electron-hole pair formation rate and better optical properties. The d-state to d-state transitions of the Cr(II) ion in the wire occur in the mid-infrared and near-infrared red regions and are shifted to the high energy side by N co-doping. Furthermore, we correlated the optical band gap of ZnS nanowire and the d-d transition peak of Cr ions under different modes of magnetic coupling, and we found that the optical band gap and d-state to d-state transition peaks of Cr(II) ions shift to lower and higher energies in FM and AFM configurations, respectively. Such a shift in bandgap and d-d transition peaks of Cr(II) ions in the FM and AFM states of the far configuration was not observed.

UV and solar-based photocatalytic degradation of organic pollutants from ceramics industrial wastewater by Fe-doped ZnS nanoparticles

UV and solar-based photocatalytic degradation of 2,4-dichlorophenol (2,4-DCP) as an organic contaminant in ceramics industry wastewater by ZnS and Fe-doped ZnS NPs was the focus of this research. Nanoparticles were prepared using a chemical precipitation process. The cubic, closed-packed structure of undoped ZnS and Fe-doped ZnS NPs was formed in spherical clusters, according to XRD and SEM investigations. According to optical studies, the optical band gaps of pure ZnS and Fe-doped ZnS nanoparticles are 3.35 and 2.51 eV, respectively, and Fe doping increased the number of carriers with high mobility, improved carrier separation and injection efficiency, and increased photocatalytic activity under UV or visible light. Doping of Fe increased the separation of photogenerated electrons and holes and facilitated charge transfer, according to electrochemical impedance spectroscopy investigations. Photocatalytic degradation studies revealed that in the present pure ZnS and Fe-doped ZnS nanoparticles, 100% treatment of 120 mL of 15 mg/L phenolic compound was obtained after 55- and 45-min UV-irradiation, respectively, and complete treatment was attained after 45 and 35-min solar light irradiation, respectively. Because of the synergistic effects of effective surface area, more effective photo-generated electron and hole separation efficiency, and enhanced electron transfer, Fe-doped ZnS demonstrated high photocatalytic degradation performance. The study of Fe-doped ZnS's practical photocatalytic treatment capability for removing 120 mL of 10 mg/L 2,4-DCP solution made from genuine ceramic industrial wastewater revealed Fe-doped ZnS's excellent photocatalytic destruction of 2,4-DCP from real industrial wastewater.

Effect of Sm3+ ions doping on the structural and optical properties, Judd-Ofelt and radiative parameters of ZnS phosphor materials

Undoped ZnS and Sm3+ doped with varying concentration of ZnS phosphor materials were synthesized via low temperature solid state reaction method. The samples were investigated for the influence of different concentrations of Sm3+ ions on their structural and spectroscopic properties. The presence of various absorption bands in UV–Vis–NIR spectra revealed the transition from ground state to different excited states of Sm3+ ions. The Judd-Ofelt (JO) analyses were evaluated to identify the structure and the bonding around the Sm3+ ions. The high value of Ω2 intensity parameter reveals that the site symmetry is lower. The parameters such as radiative transition probabilities, radiative lifetime, branching ratio, stimulated emission cross-sections and the optical gain parameters are also evaluated. The PL spectra shows five high intensity emission bands centered at 567 nm, 590 nm, 619 nm, 641 nm and 667 nm corresponding to 4G5/2→6Hj (j = 5/2, 7/2,9/2, 11/2, 13/2) transitions and showed optimum for concentration at x = 0.03 in Zn(1-x)S. The quantum yield of the prepared optimal phosphor using integrating sphere method was found to be 10.08%. This indicates that the materials synthesized may be favorable for the applications of laser and other optical devices.

Effect of Li+ concentration on the structural and optical properties of chemically synthesized ZnS nanoparticles

ZnS nanoparticles (NPs) with different concentrations of Li-doping (0, 2.5, 4.5, 6.5, and 10.5 %) were synthesized by the co-precipitation method. Crystalline structure, surface morphologies, and optical properties were studied in detail. X-ray diffraction (XRD) and high-resolution transmission electron microscopy (HRTEM) confirmed the cubic phase of un-doped and Li doped-ZnS NPs. Scanning electron microscopy (SEM) and HRTEM images showed that un-doped and Li-doped ZnS NPs contain agglomerated particles, and agglomeration is increased by increasing Li-doping. Different vibration modes are observed in a Fourier transform infrared spectrophotometer (FTIR) analysis. Defects are observed in the photoluminescence spectra (PL) of un-doped and Li-doped ZnS NPs, and a dominant green-orange transition is observed. Absorption studies using UV–vis spectroscopy reveal a quantum confinement effect for un-doped and Li- doped ZnS NPs. The direct band gap energy (Egp) increased with increasing Li concentration in the range of 3.728–3.875 eV.

Synthesis of Cu-doped ZnS nano-powder by chemical co-precipitation process

Copper doped zinc sulphide nanopowders (ZnS: Cu NPs) were synthesized using chemical co-precipitation technique. The Cu-doping content in the NPs was varied in the range, 0–4 wt%. The undoped and Cu-doped ZnS nanoparticles were prepared at 70 °C and dried at low temperatures. The prepared powders were investigated to understand the structure, surface topography, optical and photoluminescence (PL) properties using appropriate techniques. The X-ray diffraction (XRD) studies of prepared NPs revealed the (111) plane as the dominant orientation related to the cubic structure of ZnS. Also, XRD spectra exhibited broadening of the crystal planes on increasing Cu-content in the starting solution. The topography studied revealed a change from granular shaped crystals to flower shaped surface morphology upon Cu-doping. From the optical absorption studies, it was noted that increase ofCu-doping in the starting solution, shifted the absorption edge toward the smaller wavelength. The band gap energy of the NPs was evaluated by using Tauc plots, which varied from 3.7 eV to 4.1 eV with increase of Cu-doping. The PL studies indicated a small peak at 440 nm in pure ZnS and large peak at 522 nm that are related to the characteristic bands of ZnS. The properties of ZnS: Cu NPs were analysed for their suitability for mono-grain solar cell application.

Spin configuration of T14 and A61 states in a manganese-doped wide band gap semiconductor

We probe the spin configuration of manganese's $d$ states, namely $^{4}\mathrm{T}_{1}$ and $^{6}\mathrm{A}_{1}$, in doped semiconductor quantum dots (QDs) through spin-polarized scanning tunneling spectroscopy (SP-STS). We show that the two levels have opposing spin states. Experimentally, we probed the density of states (DOS) of the undoped and manganese-doped ZnS QDs, which have a wide band gap so that the $^{4}\mathrm{T}_{1}$ and $^{6}\mathrm{A}_{1}$ energies lie within the gap. The states were viewed with a nonmagnetic and a spin-polarized tip of a scanning tunneling microscope (STM). While a nonmagnetic tip could inject electrons into the $^{4}\mathrm{T}_{1}$ and withdraw electrons from the $^{6}\mathrm{A}_{1}$ state as well, the DOS derived with a spin-polarized tip evidenced that the tip could ``see'' only one of the two energy levels, whose spin state remained parallel to that of the tip. The intensity of DOS representing the $^{4}\mathrm{T}_{1}$ and $^{6}\mathrm{A}_{1}$ of manganese thereby depended on the mutual alignment of the magnetization vectors representing the tip and the $d$ states. We have inferred that the spin configuration of $^{4}\mathrm{T}_{1}$ and $^{6}\mathrm{A}_{1}$ states is mutually antiparallel in nature; such results have been the rationale of the photoluminescence (PL) emission in such manganese-doped QDs to possess an exceptionally long lifetime.

Photoluminescence of wurtzite-type Ce-doped ZnS nanocrystals processed by a low-temperature aqueous solution approach

Undoped and Ce-doped ZnS nanocrystals with hexagonal wurtzite structure were synthesized by a low-temperature aqueous solution method that uses l-cysteine as complexing and capping agent. The morphology analysis revealed the formation of polydisperse nanocrystals with sizes in the range of 2–4 nm, while the energy dispersive X-ray spectroscopy showed that all the samples were sulfur deficient. The presence of Ce3+ species in the Ce-doped samples was confirmed by the X-ray photoelectron spectroscopy technique. UV–vis spectroscopy indicated that all samples had a blue shift of optical bandgap compared to bulk ZnS. According to the room-temperature photoluminescence studies, the spectra of Ce-doped ZnS nanocrystals exhibited a broad band emission consisting of UV and blue components, associated with ZnS defects, and a green component due to the 5d-4f transition of Ce3+.

Cobalt-substituted ZnS QDs: a diluted magnetic semiconductor and efficient photocatalyst.

Recently, understanding the origin of induced magnetic characteristics in transition metal atom-doped QDs has been a major focus owing to their potential applications in the area of spintronic devices. A detailed experimental and theoretical investigation was conducted to understand the physical properties of Co-doped ZnS QDs containing different weight percentages of Co atoms [CoxZn1-xS (x = 0.00, 0.03, 0.06, and 0.09)], prepared using chemical co-precipitation techniques. X-ray diffraction studies proved that all the prepared QDs formed an extremely pure cubic zinc blende crystallographic phase free of contaminants. The validation of the quantum dot nature of all the samples was provided by the HRTEM images, BET studies, and blue shift in the absorption spectra. Both the obtained FTIR and PL spectra at room temperature also confirmed the phase purity of the prepared QDs. The observed weak ferromagnetic behavior of the doped samples was due to the presence of p-d hybridization between the 3d levels of Co2+ ions and 3p levels of S2- ions of the host ZnS QDs. Hysteresis loops that were obtained at room temperature validated this weak ferromagnetic nature. These obtained results were also supported theoretically using DFT calculations. FDTD simulations provided a detailed explanation for the observed blue shift in the absorption spectra originating from the quantum confinement effect of doped and undoped ZnS QDs. The dielectric properties of all the samples were examined properly, and it was also found that the grain boundaries contributed effectively to providing the dielectric response. The doped ZnS sample containing more Co dopants at low frequencies showed a progressive rise in polarisation loss. In addition, Co-doped ZnS QDs are efficient photocatalysts. A pH-dependent photodegradation test of ciprofloxacin (CIP) antibiotic was conducted using 9% Co-doped ZnS QDs. It was observed that 9% Co-doped ZnS nanocatalysts has sufficient capability to degrade CIP to around 94.7% in a solution of pH 10 within one hour. Therefore, besides showing photocatalytic effects, Co-doped ZnS QDs act as ideal dilute magnetic semiconductors (DMSs) and will undoubtedly become excellent candidates for the microelectronics industry because of their special ability to exhibit spin-dependent magneto-electro-optical properties that find use in spin-polarized light-emitting diodes, solid-state lasers, and spin-transistor devices.

Er3+ and Sm3+ co-doped ZnS quantum dots: Judd-Ofelt, luminescent properties and energy transfer

ZnS semiconductor quantum dots (QDs) co-doped with Er3+ and Sm3+ ions were successfully fabricated using a wet chemical method. The presence of Er3+ and Sm3+ in the ZnS host was confirmed using X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS). XRD and transmission electron microscopy (TEM) analyses showed that the QDs had a zinc blende (ZB) structure with spherical shape and a particle size of approximately 4 nm. The optical properties of ZnS QDs were investigated by changing the Er3+ ion concentration and fixing the Sm3+ ion concentration. Judd-Ofelt (J-O) intensity parameters were determined from optical absorption spectra. The obtained J-O parameters illustrate the covalency related to the ligands and rare-earth ions. The radiative transition probabilities (Ar), branching ratios (βr), and radiative lifetimes (τr) of various excited states of the Er3+ ions were calculated. For the first time, the energy transfer (ET) processes from the ZnS host to Er3+ ions and from Er3+ to Sm3+ ions were confirmed and explained in detail. Er3+ and Sm3+ co-doped ZnS QDs showed a very long lifetime (up to milliseconds) compared to undoped ZnS. This exciting property has potential applications in photocatalysis, biosensing, and photovoltaics.

Microwave-assisted synthesis and characterization of undoped and manganese doped zinc sulfide nanoparticles

Undoped and Mn-doped ZnS nanocrystals were produced by the microwave-assisted solvothermal method and characterized by X-ray diffraction, photoluminescence spectroscopy and scanning electron microscopy with energy-dispersive X-ray spectroscopy. All samples have the cubic zinc blende structure with the lattice parameter in the range of a = 5.406–5.411 Å, and the average size of crystallites is in the range of 6–9 nm. These nanoparticles agglomerate and form large grains with an average size of up to 180 nm. The photoluminescence of the undoped ZnS sample shows a broad emission band located at 530 nm, attributed to the defects at the surface of nanoparticles. In all Mn-doped samples, the emission peak at 598 nm was observed assigned to the characteristic forbidden transition between excited (4T1) and ground (6A1) levels of Mn2+. Synchrotron radiation X-ray absorption spectroscopy at the Zn and Mn K-edges combined with reverse Monte Carlo (RMC) simulations based on the evolutionary algorithm confirms that manganese ions substitute zinc ions. However, the difference in the ion sizes (R(Mn2+(IV)) = 0.66 Å and R(Zn2+(IV)) = 0.60 Å) is responsible for the larger interatomic distances Mn–S (2.40(2) Å) compared to Zn–S (2.33(2) Å). The static structural relaxations in ZnS:Mn nanoparticles are responsible for the large values of the mean-square displacements factors for Zn, S and Mn atoms obtained by RMC simulations.

Effect of Fe doping on the structural and optical properties of ZnS macro-spheres

ObjectiveDoping of ZnS by the transition metal ions has perceived considerable attention in industrial applications in light-emitting displays and optical sensors. Herein, we have studied the effect of Fe doping on structural and optical properties of ZnS macro-spheres. MethodsZnS macro-sphere with and without Fe doping are synthesized by a simple and cost-effective co-precipitation method and characterized by X-ray diffraction (XRD), Field emission scanning electron microscopy (FESEM), and Fourier transform infrared (FTIR) spectroscopy to study the structural properties. Moreover, UV-Vis spectroscopy was performed to investigate the optical properties of un-doped and Fe-doped ZnS macro-spheres. ResultsXRD confirms the polycrystalline nature of single-phase cubic structure of as-grown and Fe-doped ZnS macro-spheres. Moreover, the Fe substitute in ZnS inter-layer space thickness decreased and the crystallite size increased. FESEM shows the morphology of semi-spherical macro-spheres with wide micrometer-size distribution (~ 7–8 µm), agglomerated from several closely embedded primary nano-grains. FTIR spectra found that the specific functional groups associated with the vibrational modes of samples present in the range of 400–800 cm−1. UV-Visible spectroscopy shows that the absorption maximum is red-shifted in the case of Fe-doped ZnS. The band gap of as-grown ZnS macro-sphere was found to be 3.46 eV, which was significantly tuned to 3.22 eV by Fe dopant. ConclusionsThe synthesized Fe-doped ZnS macro-spheres show improved structural and optical properties and potential optoelectronic device applications.

Fast and effective catalytic degradation of an organic dye by eco-friendly capped ZnS and Mn-doped ZnS nanocrystals.

Undoped and manganese doped ZnS nanocrystals encapsulated with thioglycolic acid(ZnS-TGA) were synthesized and characterized with different techniques, and finally tested in the photodegradation of a methyl orange in aqueous solution under UV and sunlight irradiations. FTIR and X-ray diffraction results confirmed the functionalization of these nanocrystal surface by thioglycolic acid and the formation of crystalline structures of ZnS and Mn-doped ZnS with cubic and hexagonal phases. Calculated average size of ZnS nanocrystals was in the range of 2-3nm. It was observed a blue shift of the absorbance threshold and the estimated bandgap energies were higher than that of Bulk ZnS thus confirming the quantum confinement effect of charge carriers. Photoluminescence spectra of ZnS nanocrystals exhibited emission in the range of 410-490nm and the appearance of an additional emission band around 580nm (2.13eV) connected to the 4T1 → 6A1 transition of the Mn2+ions. Photodegradation of methylene orange with undoped and Mn-doped ZnS-TGA nanocrystals was investigated. Dye adsorption prior to photocatalysis using nanocrystals was studied via kinetic and equilibrium experiments. The maximum dye adsorption capacity on doped ZnS-TGA was ~ 26.98mg/g. The adsorption kinetic was found to follow the pseudo-second-order kinetic model. A statistical physics model was used to analyze the equilibrium data where the calculated adsorption energy was 17-18kJ/mol. It was concluded that the dye adsorption was associated to the hydrogen interaction where the removal process was feasible and multi-molecular at 25°C. The photocatalytic activity of undoped ZnS nanoparticles under UV irradiation showed better efficiency than doped nanocrystals thus indicating that manganese doping generated a dropping of the photocatalytic degradation of the dye. Dye degradation efficiency of 81.37% using ZnS-TGA nanocrystals was achieved after 6min, which indicated that ZnMnS-TGA nanocrystals may be considered an alternative low cost and environmental friendly material for facing water pollution caused by organic compounds via photodegradation processes.

Morphological and structural characterization of Pb:ZnS nanostructure films deposited by simple thermal evaporation

ZnS nanostructure films were deposited by a thermal evaporation method. Two films were prepared; the first was zinc sulfide (undoped ZnS) and the second was Pb-doped zinc sulfide (Pb:ZnS). X-ray photoelectron spectroscopy (XPS) and energy-dispersive X-ray spectroscopy (EDX) techniques were employed to investigate the element contents of the two films; they were found to be stoichiometric. Surface and growth evolution of films were explored by SEM images and found to have morphological development from spherical forms into nanostructure lookalike Taraxacum erythrospermum (Dandelion) with increasing the Pb from 0 wt.% to 12 wt.%. A structural study was performed using XRD patterns. The films have ZnS hexagonal structure (002) preferential orientation with various Pb percentages. In the doped sample, ZnS nanostructure and pores and nanowires (NWs) were formed with a mean diameter less than 50 nm; the undoped film had dense structure and was thin. This study illustrated the influence of Pb doped on the morphological modification of ZnS films.

Highly Efficient Hydrogen Production in the Photoreforming of Lignocellulosic Biomass Catalyzed by Cu,In‐Doped ZnS Derived from ZIF‐8

AbstractCu,In‐doped ZnS (CIZS) is fabricated from a metal–organic framework (MOF) precursor, namely a Cu,In‐doped zeolitic imidazolate framework (ZIF‐8). The prepared CIZS shows high activity for hydrogen production in the photoreforming reaction of lignocellulosic biomass under simulated sunlight. The activity is 125‐fold greater than that of undoped ZnS produced by the same method. Compared to CIZS synthesized by the conventional solvothermal method for sulfide photocatalysts, the CIZS synthesized via a MOF is characterized by high crystallinity and an 8.9‐fold increase in hydrogen production activity. This catalyst also exhibits better performance than conventional photoreforming catalysts, while it is free from toxic substances, such as Cd, or expensive cocatalysts, like Pt. In addition, the prepared CIZS is stable in photocatalytic reactions and achieves an apparent quantum yield of ≈28% under 360‐nm light irradiation.

Optimization of chemically sprayed ZnS films by Mn doping

In this study, undoped and Mn doped ZnS films were grown on microscope glass substrates at substrate temperature of 400 ± 5 °C by using a low cost Ultrasonic Spray Pyrolysis technique, and the effect of Mn doping on some physical properties of ZnS films was investigated. Structural, optical, electrical and morphological properties of all films were analyzed using X-ray diffractometer (XRD), UV–Vis spectrophotometer, two-probe technique and atomic force microscope (AFM), respectively. X-ray diffraction studies showed that all films were formed in ZnS hexagonal structure and the crystallization levels of the films were relatively improved due to the increase in the Mn doping ratio, especially for 4% doped films. It was determined that the average transmittance value of undoped ZnS film in the visible region is 38% and this value increases to 60% for the sample doped by Mn at the highest rate (12%). The band gap values of the films were calculated using the Tauc equation and determined to be between 3.82 and 3.94 eV. Electrical resistivity values of the films decreased significantly due to the Mn doping. Mn doping also caused ZnS films to have uniform surface morphologies consisting of noticeable particle formations. Figure of merit calculations showed that Mn doping has a favorable effect on ZnS films and ZnS:Mn (12%) films may be promising materials for applications such as photovoltaic solar cells and optoelectronic devices.

Mn-doped ZnS synthesis in DABCO based ionic liquid: Morphology and electrochemical sensing performance for isoprenaline analysis

ZnS nanostructures with Mn2+ doping (5%) have been prepared in ionic liquid (IL) through the reflux method. The undoped ZnS and Mn2+ doped ZnS (Mn.ZnS) nanostructures produced in the presence and lack of IL, were analyzed using X-ray diffraction, scanning electron microscopy, and Brunauer–Emmett–Teller methods. Then, the surface of the glassy carbon electrode (GCE) was modified by synthesized nano ZnS and Mn.ZnS and electro-activated by successive cyclic voltammetry (CV) in a NaOH solution. The sensing ability of the modified GCEs towards isoprenaline (ISP) was examined by CV and differential pulsed voltammetry (DPV) for which less over potentials with sharper redox currents were resulted compared to the bare GCE. The optimized Mn.ZnS/GCE was stable in buffer solutions in the pH range of 2–8 and exhibited a linear response for ISP concentrations in the range of 0.5–30 μM with promising sensitivity of 2.1 μA/μM and low detection limit of 90 nM. Adequate selectivity for determining ISP in the presence of other biological compounds such as ascorbic acid, uric acid at pH 5.0 confirmed the potential applicability of Mn.ZnS/GCE for ISP sensing in real biological samples. Finally, an electrochemical mechanism for the catalytic oxidation of ISP was proposed.