Zinc Sulfide Surface Research Articles

Oxygen vacancy-mediated activation of Zn-O bonds at the S-scheme heterostructure interface for efficient uranium collection and resistance to biological contamination

Efficient reduction of U(VI) to U(IV) during seawater uranium extraction remains a challenge. Here, cerium dioxide quantum dots were bonded to the surface of indium zinc sulfide (ZIS) to form ZIS composite cerium dioxide quantum dots (ZIS/QDs-Ce). The oxygen vacancies are able to activate the Zn-O bonds at the ZIS and QDs-Ce interfaces, thus enabling the constructed S-scheme heterojunction to show great potential in facilitating the separation and transfer of photogenerated carriers. ZIS/QDs-Ce exhibited high anti-bio-pollution activity by generating biotoxic free radical reactive oxygen species (ROS). The photo-induced reduction of uranium by ZIS/QDs-Ce in 10 ppm uranium spiked simulated seawater reached 99.6 %. Oxygen vacancies cause distortions in the crystal field, and the Zn-O bond activation process triggers the movement of ZIS/QDs-Ce from the singlet low-spin state to the stable triplet state, resulting in free-carrier trapping centers and optimized electronic energy band structures. ZIS/QD-Ce has superior uranium extraction capabilities and is highly recommended for uranium extraction from seawater.

NiMoP2 co-catalyst modified Cu doped ZnS for enhanced photocatalytic hydrogen evolution

The design of a low-cost, efficient and durable co-catalyst for hydrogen evolution is of great significance for improving photocatalytic activity. In this work, a NiMoP2/Cu-ZnS composite photocatalyst was prepared by in-situ growth of NiMoP2 on the surface of copper-doped zinc sulfide (Cu-ZnS). The test results showed that the hydrogen production rate of the optimized NiMoP2/Cu-ZnS under visible light irradiation was significantly improved. Among them, NiMoP2/Cu-ZnS-1 exhibited the highest photocatalytic activity (5.13 mmol·g−1·h−1), which was 2.47 times that of Cu-ZnS and maintained good stability during the reaction. The improvement of hydrogen production performance of the photocatalyst was mainly attributed to the synergistic effect of Cu-ZnS and co-catalyst NiMoP2. The ohmic contact formed between Cu-ZnS and NiMoP2 could improve the separation efficiency of photogenerated carriers and reduce the overpotential of H2 evolution. Besides, NiMoP2 was found to provide the active site for the reduction reaction, and accelerate the transfer efficiency of photogenerated electrons. This strategy opens up a new way for the construction of co-catalyst modified semiconductor materials to improve the photocatalytic hydrogen production rate.

Enhancement of the optical and electrical properties of poly ethyl methacrylate/polyvinyl chloride-zinc sulphide (PEMA/PVC@ZnS) ternary nanocomposite films

Our research introduces a novel ternary nanocomposite consisting of polyethyl methacrylate/polyvinyl chloride-Zinc sulphide nanoparticles (PEMA/PVC@ZnS). Zinc sulphide (ZnS) nanoparticles were produced via a chemical method and then dispersed at different concentrations (0.02, 0.05, 0.08, and 0.1 wt%) in a single step within the PEMA/PVC blend. The resulting PEMA/PVC@ZnS nanocomposite films were analyzed to investigate their spectroscopic and electrical properties. The dielectric parameters of the samples were also studied in detail. X-ray diffraction (XRD) data indicated an increase in the amorphous region and demonstrated the interaction between ZnS and PEMA/PVC. Fourier transform infrared (FT-IR) results confirmed the specific interactions in PEMA/PVC@ZnS nanocomposites. The synthesized films showed a distinct absorption band at 432 nm, which was attributed to the ZnS surface plasmon resonance. As the concentration of ZnS in PEMA/PVC increased, the band gap energies decreased for both direct and forbidden transitions. Optical parameters such as the extinction coefficient (k), refractive index (n), dielectric constants (ε′ and ε''), optical conductivity (σ(opt.), and photoluminescence (PL) were also studied. The values of dielectric permittivity and dielectric modulus from AC measurement of PEMA/PVC@ZnS nanocomposite films increased with increasing ZnS content. The data suggest that PEMA/PVC@ZnS nanocomposite films exhibit excellent optical and electronic properties, making them suitable for use in various electric and optoelectric applications.

Theoretical Simulation and Preparation of Anti-reflection Characteristics of Zinc Sulfide Surface Microstructure

Theoretical Simulation and Preparation of Anti-reflection Characteristics of Zinc Sulfide Surface Microstructure

Probe into hydrophobic mechanism of solid-liquid interface during separation recovery of Zn from Fe and Cd by sulfide precipitation flotation with a novel “plane” collector

Sulfide precipitation flotation process is one of the effective methods to recover heavy metal ions from wastewater, nevertheless, the selectivity and collection ability for flotation process are limited by the structure of collector group currently. While, the original collectors with novel minerophilic groups have been hardly reported. In this sense, a novel “plane” chelating collector 5-heptyl-1,3,4-oxadiazole-2-thione (HpODT) containing N-, O- and S-donor ligands was prepared and first used for selective flotation of Zn from Fe and Cd by sulfide precipitation flotation. Micro-flotation showed that HpODT exhibited stronger hydrophobization and selectivity to zinc sulfide and achieved higher flotation recovery than sodium isobutyl xanthate (SIBX). ζ-Potential revealed that HpODT might attached to the zinc sulfide surface by chemical adsorption. UV spectra of HpODT with metal ions suggested that HpODT had chemical interaction with Zn2+, accompanying with the release of H+. According to FTIR, XPS and DFT calculation results, a four-membered HpODT-Zn chelating structure was proposed and predicted, meanwhile the hydrophobic HpODT-Zn surface compound was covered on zinc sulfide surface under the action of ZnS and ZnN bonds. Considering the above results, the surface hydrophobicity of zinc sulfide improved obviously after attached with HpODT, thereby promoting the flotation recovery and selectivity of Zn2+, which is significant for effective recovery of zinc from wastewater of complex metal species.

Subwavelength Quasi-Periodic Array for Infrared Antireflection.

Infrared antireflection of a zinc sulfide (ZnS) surface is important to improve performance of infrared detector systems. In this paper, double-pulse femtosecond laser micro-machining is proposed to fabricate a subwavelength quasi-periodic array (SQA) on ZnS substrate for infrared antireflection. The SQA consisting of approximately 30 million holes within a 2 × 2 cm2 area is uniformly formed in a short time. The double-pulse beam can effectively suppress the surface plasma shielding effect, resulting in obtaining a larger array depth. Further, the SQA depth is tunable by changing pulse energy and pulse delay, and can be used to readily regulate the infrared transmittance spectra as well as hydrophobicity. Additionally, the optical field intensity distributions of the SQA simulated by the rigorous coupled-wave analysis method indicate the modulation effect by the array depth. Finally, the infrared imaging quality captured through an infrared window embedded SQA is evaluated by a self-built infrared detection system.

Antireflective array on zinc sulfide fabricated by femtosecond laser

Surface antireflection of zinc sulfide (ZnS) is crucial to improve the performance of infrared windows. In this study, femtosecond laser Bessel beam micromachining is proposed to fabricate antireflective microstructures (ARMs) on ZnS to suppress surface Fresnel reflection. The ARM consisting of approximately one hundred thousand holes within 30 × 30 mm2 is uniformly spread on the ZnS surface. The Fabry-Perot (FP) and Mie resonances in the multi-resonant surface work together to reduce reflection and are enhanced with increasing ARM depth. The ARM depth is tunable by adjusting the pulse energy and is utilized to facilely regulate the reflectance spectra as well as wettability. Finally, the fabricated ARM with wide-angle antireflection and hydrophobicity proved the effectiveness of the proposed method.

Sustainable micro-activation of dissolved oxygen driving pollutant conversion on Mo-enhanced zinc sulfide surface in natural conditions

The activation of inert oxygen (O2) often consumes enormous amounts of energy and resources, which is a global challenge in the field of environmental remediation and fuel cells. Organic pollutants are abundant in electrons and are promising alternative electron donors. Herein, we implement sustainable microactivation of dissolved oxygen (DO) by using the electrons and adsorption energy of pollutants by creating a nonequilibrium microsurface on nanoparticle-integrated molybdenum (Mo) lattice-doped zinc sulfide (ZnS) composites (MZS-1). Organic pollutants were quickly removed by DO microactivation in the MZS-1 system under natural conditions without any additional energy or electron donor. The turnover frequency (TOF, per Mo atom basis) is 5 orders of magnitude higher than those of homogeneous systems. Structural and electronic characterization technologies reveal the change in the crystalline phase (Zn-S-Mo) and the activation of π-electrons on six-membered rings of ZnS after Mo doping, which results in the formation of a nonequilibrium microsurface on MZS-1. This is the key for the strong interfacial interaction and directional electron transfer from pollutants to MZS-1 through the delocalized π-π conjugation effect and from MZS-1 to DO via Zn-S-Mo, as demonstrated by electron paramagnetic resonance (EPR) techniques and density functional theory (DFT) calculations. This process achieves the efficient use of pollutants and the low-energy activation of O2 through the construction of a nonequilibrium microsurface, which shows new significance for water treatment.

Graphene‐doped ZnS nanoparticles synthesized via hydrothermal route for enhanced electrocatalytic performance

AbstractEnergy and ecological issues increase high stress on the growth of a sustainable energy system. Better electrocatalysts is an imperative way to achieve this goal. This manuscript highlights the electronic energy state and surface area engineering of zinc sulfide (ZnS) in the nanoscale regime. These properties make ZnS, an appropriate electrocatalyst for various energy applications. It was attained by controlling the concentration of graphene into ZnS nanoparticles. Graphene‐doped ZnS nanoparticles were synthesized by simple hydrothermal route. Graphene hugely affects the structural, surface, optical, and electrochemical properties of ZnS nanoparticles. Here, 10% doping of graphene into ZnS nanoparticles double its surface area, and consequently, all other properties get varied. This sample shows the highest specific surface area of 143.05 m2/g and the highest pore diameter value of 6.02 nm. Electrocatalytic performance for synthesized samples has been verified using electrochemical impedance spectra (EIS) and cyclic voltammetry (CV) analysis. Using CV data analysis, peak current response with scan rate suggests that synthesized samples with higher graphene concentration have poor capacitive behavior. ZnS with 10% concentration of graphene possesses the highest capacitive behavior due to the fast transfer of charge/ions. Rate of flow of charge/ions into or on the electrodes is measured by a quantity called diffusion coefficient, have been calculated. Hence, the optimization of the doping concentration of graphene on ZnS is essential to obtain enhanced properties for energy applications. Also, the large concentration of graphene shield the absorption of electrolyte on ZnS surface, leading to weak electrocatalytic performance. EIS analysis reveals that smaller solution resistance and charge transfer resistance values are a sign of better electrical conductivity and electrocatalytic activity of the electrode materials. Various other characteristics studies like field emission scanning electron microscopy (FESEM), Fourier transform infrared (FTIR), and X‐ray photoelectron spectroscopy (XPS) have been done to confirm graphene‐doped ZnS nanoparticles’ formation and compare the properties variation from pure ZnS to graphene‐doped ZnS nanoparticles.

Static wetting angles of water and sulphur at the zinc sulphide surface modified with anionic surfactants and their combinations

This paper looks at the effect produced by surface modification of the super pure zinc sulphide monocrystals with certain surfactants and their combinations (sodium lignosulphonate (SLS), sodium dodecyl sulphate (SDS), sodium dodecylbenzenesulphonate (SDBS) and the following combinations: SLS + SDS, SLS + SDBS on the surface angle of wetting with water and elemental sulphur melt. It was found that as the concentration of individual surfactants in the solution rose, so did the wetting ability of the mineral surface. Thus, at the surfactant concentration of 0.8 g/dm3 the water wetting angle reaches 48.4o for SLS, 22.5o for SDS and 10.3o for SDBS; the elemental sulphur wetting angle is 71.3o for SLS, 76.9o for SDS and 67.9o for SDBS. The work of adhesion in the system ZnS – Surfactant – Н2О increases by 9–11%, and in the system ZnS – Surfactant – S0 — by 5–8%. When using the combinations SLS + SDS (СSLS = 0.2–0.8 g/dm3) and SLS + SDBS (СSLS = 0.2 g/dm3), inverse surface wetting of zinc sulphide with elemental sulphur melt is observed. The maximum wetting angles reached are 93o and 85o, correspondingly. The work of adhesion and the spreading coefficient expectedly decrease. The paper analyzes the effect of individual surfactants and their combinations on the pressure leaching of zinc sulphide concentrate. The use of individual surfactants intensifies the transition of valuable components into the solution. The biggest increase in recovery was seen when using SLS, and namely 27–32% for zinc and 11–16% for copper. The recovery of zinc increased by 31–41% in the presence of SLS + SDS and by 27–34% in the presence of SLS + SDBS. This research was funded by the Russian Science Foundation, Grant No. 18-19-00186.

Optical Properties of Zinc Sulfide Nanopowders and ZnS/Ag2S Heteronanostructures

Nanopowders of zinc sulfide (ZnS) and ZnS/Ag2S heteronanostructures were synthesized by chemical deposition from aqueous solutions. A change in the ratio between the concentrations of reagents allowed us to obtain ZnS nanopowders with a particle mean size from 2 to 10 nm. The Ag2S nanoparticle size in the resulting heteronanostructures was 9–30 nm and the ZnS surface layer thickness was equal to 4–5 nm. The diffuse reflectance spectra for nanostructured ZnS and ZnS/Ag2S heteronanostructures were measured. Based on the analysis of the obtained spectra, the bandgap energy Eg in the studied sulfide nanostructures was estimated. Upon a decrease in the nanoparticle size from 10 to 2 nm, the Eg value in ZnS nanopowders increased in a range of 3.17–3.36 eV. An increase in the content of Ag2S in the ZnS/Ag2S heteronanostructures led to a decrease in the bandgap energy and a decrease in the luminescence intensity.

Second harmonic generation in zinc sulfide by femtosecond laser irradiation

Second harmonic generation (SHG) has been observed from zinc sulfide (ZnS) under linearly polarized and circularly polarized femtosecond laser excitations. The output power of SHG signal at 513 nm exhibits a quadratic relationship to the input power of femtosecond laser at 1026 nm, which can figure out the effective SHG response of 2.12 pm/V in ZnS. Additionally, the total, vertical, and horizontal SHG signals all demonstrate well defined cosine-like curves with approximate periods of 40°, indicating a textured crystallized material rather than randomly orientated crystals. Finally, the relative position between the laser focus point and ZnS surface could be detected by the relationship between the SHG power and sample step, due to the regulation of the SHG signal by the power density of incident laser, which is also determined by the relative position. This work may pave the way towards nonlinear optical architectures and femtosecond laser machining.

РАЗВИТИЕ МЕТОДА ЛЮМИНЕСЦЕНТНОГО КОНТРОЛЯ СОСТАВА ПЛАЗМЫ И ОБРАБАТЫВАЕМОЙ ПОВЕРХНОСТИ В ТЕХНОЛОГИИ АНТИКОРРОЗИОННОЙ ЗАЩИТЫ НЕФТЕГАЗОВОГО ОБОРУДОВАНИЯ

Актуальность. Надежность и целостность нефтедобывающего оборудования, сроки его эксплуатации обеспечиваются комплексом мер по борьбе с коррозией, в частности использованием технологий газопламенного напыления защитных покрытий на проектируемые или восстанавливаемые детали. В данных технологиях эффективным методом контроля за состоянием состава плазмы и качества напыляемой поверхности может служить явление гетерогенной хемилюминесценции. Гетерогенные хемилюминесцентные реакции обладают селективностью и высокой чувствительностью к типу поверхности и сорту возбуждающего газа. Использование оптических методов для изучения, контроля и управления в неравновесных системах газ–твердое тело открывает новые аналитические и аппаратурные возможности в физике поверхности, химии, плазмохимии, технологии полупроводников и люминофоров, в решении экологических проблем. Изучение процессов адсорбции–десорбции, диссоциации, диффузии, рекомбинации газовых частиц, дефектообразования и роста кристаллической решетки с использованием явления гетерогенной хемилюминесценции является актуальной задачей физики конденсированного состояния. Поскольку явление гетерогенной хемилюминесценции реализует возможности осуществления селективных экспресс-методов анализа при простом аппаратурном оснащении с пределом обнаружения свободных атомов, радикалов, примесей в газовой фазе и в составе поверхностных слоев конденсированных сред до 10–6 % (мол). Цель: исследование процессов в неравновесных системах газ – твердое тело и определение параметров этого взаимодействия на основе регистрации характеристик гетерогенной хемилюминесценции; разработка нестационарных методов определения параметров взаимодействия газ–твердое тело с использованием явления гетерогенной хемилюминесценции, контроль параметров газовой среды и состояния поверхности конденсированных сред. Объекты: атомно-молекулярные пучки водорода, кристаллофосфор ZnS–Mn2+, приповерхностные области взаимодействия газ – твердое тело. Методы: методы, основанные на явлении гетерогенной хемилюминесценции в атомарном водороде для определения скоростей адсорбции и рекомбинации атомов Н, десорбции молекул H2, энергии активации десорбции молекул водорода с поверхности ZnS–Mn2+. Методом «темновой» паузы определена скорость рекомбинации адсорбированных атомов водорода по механизму Лэнгмюра–Хиншелвуда. Результаты. Выполнено сравнительное исследование люминесценции ZnS–Mn2+ при возбуждении светом (фотолюминесценции) и атомарным водородом (гетерогенной хемилюминесценции). Изучены спектрально-кинетические характеристики люминесценции. Установлены механизмы и параметры взаимодействия атомов водорода с поверхностью сульфида цинка (сечения, частотные факторы, энергии активации) с использованием спектрально-кинетических характеристик гетерогенной хемилюминесценции. Показано, что люминофор ZnS–Mn2+ может служить экспресс датчиком восстановительной компоненты плазмы (водород). Явление гетерогенной хемилюминесценции составляет основу оперативных методов контроля начальных стадий модификации поверхности твердых тел в процессах пучково-плазменной обработки материалов.

Two-dimensional correlation analysis of continuous online in situ ATR-FTIR on the adsorption of heptyl xanthate at the surface of ZnS and Pb(II) activated ZnS

Zinc sulfide (ZnS) is an important and widely used semiconductor material. To improve the flotation efficiency of zinc minerals and explore corresponding mechanisms has been a central topic of flotation technology and flotation chemistry. ZnS with a high purity and a large surface area was synthesized using zinc nitrate as a zinc source and sodium sulfide as a sulfur source in the laboratory. The synthetic ZnS was then activated with lead nitrate in order to understand involving mechanism and consequently improve its flotation efficiency with xanthates. The adsorption of heptyl xanthate (KHX) at the surface of ZnS and Pb(II) activated ZnS were examined as a function of time using continuous online in situ attenuated total reflectance Fourier transform infrared (ATR-FTIR) spectroscopy. The two-dimensional IR correlation analysis indicates that lead xanthate and zinc xanthate coexisted on the Pb(II) activated ZnS surface and lead xanthate formed prior to zinc xanthate at the surface of Pb(II) activated ZnS. The activation by lead ions increased the adsorption amount and rate constant of KHX. The KHX adsorption onto both ZnS and Pb(II) activated ZnS obeys the pseudo first order kinetic model and the desorption with deionized water is negligible after 20–30 min.

Effect of silica on the ZnS nanoparticles for stable and sustainable antibacterial application

AbstractSilica‐capped Zinc Sulfide (ZnS) nanoparticles were synthesized for the use as stable and long‐term antibacterial agents because silica is a very important component in food packaging applications for moisture absorption in tune with its property of biocompatibility and water solubility. The variation in morphological and optical properties of core‐shell nanostructures was studied by changing the concentration of silica in a core‐shell combination. The structural and morphological properties of silica‐capped ZnS have been observed by powder X‐ray diffraction (PXRD) and transmission electron microscopic (TEM) studies, respectively. Uncapped ZnS nanoparticles with particle size of 2‐4 nm in a highly agglomerated state have been observed from TEM, which shows that they can be used only for short‐term antibacterial action despite its excellent zone of inhibition (antibiotic sensitivity). However, ZnS/SiO2 core‐shell nanostructures are highly monodisperse in nature and the particle size increases up to 5‐8 nm with increase in silica concentration. Fourier‐transform infrared spectroscopy (FTIR) analysis confirms the formation of silica capping on the ZnS surface. The inhibition of defect‐related emission by silica capping in energy‐resolved photoluminescence studies also shows the formation of very stable ZnS nanoparticles. To study the antibacterial properties of the pure and silica‐capped ZnS nanostructure the agar‐well diffusion method was employed against both gram‐positive and gram‐negative bacteria. The obtained results indicate that pure ZnS shows excellent antibacterial action but it can last only for few days.

Preparation and protection of ZnS surface sub-wavelength structure for infrared window

Zinc sulfide (ZnS) is one of the most important far-infrared optical candidate materials. However, it is indispensable for ZnS to improve its antireflection and protection especially under harsh environments. Compared with conventional surface antireflective films, surface sub-wavelength structures (SWSs) have some unique advantages. In this paper, dewetting nickel dots as etching mask on ZnS substrates were obtained by thermal annealing of as-sputtered Ni films on the intermediate layers of as-sputtered silicon films. ZnS SWSs were then prepared by inductively coupled plasma (ICP) etching. Finally, HfO2 films were deposited on ZnS SWSs by atomic layer deposition. The influences of SWSs and ALD-derived HfO2 films on the transmittance and protection of ZnS were both investigated. The experimental results show that ZnS SWSs can increase both far-infrared transmittance and surface hydrophobicity. Meanwhile, ALD-derived HfO2 films can provide good protection. Compared with bare ZnS, HfO2-coated ZnS with double-sided SWS exhibits average transmittance of 79.2% other than initial 69.1% in 8–12 μm, better hydrophobicity with the wetting angle of 119.7°, and higher composite nano-hardness increased from 25.00 to 38.68 GPa. ALD derived HfO2 films on ZnS surface sub-wavelength structures have excellent application prospective for infrared optical windows.

Robust and Biocompatible Functionalization of ZnS Nanoparticles by Catechol-Bearing Poly(2-methyl-2-oxazoline)s.

Zinc sulfide (ZnS) nanoparticles (NPs) are particularly interesting materials for their electronic and luminescent properties. Unfortunately, their robust and stable functionalization and stabilization, especially in aqueous media, has represented a challenging and not yet completely accomplished task. In this work, we report the synthesis of colloidally stable, photoluminescent and biocompatible core-polymer shell ZnS and ZnS:Tb NPs by employing a water-in-oil miniemulsion (ME) process combined with surface functionalization via catechol-bearing poly-2-methyl-2-oxazoline (PMOXA) of various molar masses. The strong binding of catechol anchors to the metal cations of the ZnS surface, coupled with the high stability of PMOXA against chemical degradation, enable the formation of suspensions presenting excellent colloidal stability. This feature, combined with the assessed photoluminescence and biocompatibility, make these hybrid NPs suitable for optical bioimaging.

Promoting lithium polysulfide/sulfide redox kinetics by the catalyzing of zinc sulfide for high performance lithium-sulfur battery

Entrapping polysulfide from dissolution into electrolyte by strong chemisorption of polar materials has been widely reported in lithium-sulfur (Li-S) battery. Here, for the first time, zinc sulfide (ZnS) was demonstrated as an activation catalyst in Li-S battery to suppress the soluble polysulfide shuttle effect by powering kinetics redox reactions of lithium polysulfide/sulfide. Kinetic analyses comprehensively identify that ZnS not only facilities polysulfide redox kinetics in liquid phase (Li2S8→Li2S6→Li2S4), but also promotes the effective decompositions of lithium sulfide (Li2S). Furthermore, first-principle calculations confirm that the low lithium ion diffusion barrier on the surface of ZnS promotes the redox reaction between lithium ion and sulfur species; and the low migration energy barrier of polysulfide on its surface guarantees the fast diffussion of polysulfides from the ZnS surface to the nearby conductive substrate, thus effectively smoothes polysulfides’ entrapping-diffusion-conversion mechanism across the ZnS interface, resulting in the highly reversible electrochemical performance. As evidenced by the ex situ SEM and visible experiment, the reaction between migrated sulfur species and lithium anode was significantly alleviated, and the insulating Li2S/Li2S2 was uniformly deposited on the ZnS-CB/S cathode. This ZnS cathode based Li-S battery exhibits outstanding performance including an excellent retained discharge specific capacity of 589 mA h gsul−1 with the high sulfur loading of 7 mg cm−2 (200 cycles) and extended cycling stability at the high current rate of 2 C, 5 C (632, 388 mA h gsul−1 after 1000 cycles).

Pollutant degradation of different organic dyes using the photocatalytic activity of ZnO@ZnS nanocomposite materials

The current work focuses mainly to overcome the low surface properties drawbacks of Zinc oxide (ZnO) by spreading of ZnO nanoparticles on the surface of Zinc sulfide (ZnS) synthesized by sol-gel route using Cetyltrimethylammonium-Bromide (CTAB) as capping agent to form ZnO@ZnS nanocomposites (NCs) materials with new properties gathering between the two nanoparticles materials. ZnO@ZnS is an active semiconductor with high efficiency for removal of many organic dyes and pollutant degradation. Different techniques like XRD, BET, FESEM, PL, Uv-vis spectroscopy as well as photocatalytic activity of ZnO, ZnS and ZnO@ZnS results were investigated to confirm the nanostructure and homogenous distribution of particles inside the matrix. In addition, the scavenger study indicates that all charge carriers and reactive radicals contribute by roughly close extent, which explains the observed increase in the rate of degradation. Catalytic reactivity of ZnO@ZnS NCs exerts the same extent of higher efficiency for removal of methylene blue (MB) as well as Eosin dyes under UV lights. Furthermore, the Chemical Oxygen Demand [COD] study indicates that the majority of dyes were removed. The COD of the dye solution before and after the photo catalytic process was calculated, where it is found that COD reduces from 25.4 ppm for pure methylene blue dye to 11.1 ppm after 90 min and 2.4 ppm after 120 min irradiation by ultra violet applied on ZnO@ZnS NCs. Moreover, the recycled experiments for the photodegredation of eosin dye under ultra violet lights were performed to evaluate the stability of ZnO@ZnS nanocomposites after 5 successive cycles.

Binding of Mercury Species and Typical Flue Gas Components on ZnS(110)

Environmentally benign zinc sulfide (ZnS), consisting entirely of “active” sites, has shown promising efficiency for capturing mercury from flue gas in recent experimental studies. In this work, the binding mechanism of Hg0 on the ZnS(110) surface was investigated by the density functional theory (DFT) method. Meanwhile, the binding of two additional mercury forms, HgCl and HgCl2, and three essential flue gas components, H2O, SO2, and HCl, and their further effects on the strength of Hg0 binding on the ZnS(110) surface were also evaluated. The results showed that, consistent with experimental observations, Hg0 can be chemisorbed on the ZnS(110) surface with binding energies (BEs) as high as −87.80 kJ/mol. The enhanced electrostatic characteristics on the activated surface, especially the Zn sites, are beneficial to exciting the outer-shell electrons of Hg0 and thereby enhancing the binding strength of the material. HgCl and HgCl2 were found to be chemisorbed with the highest BEs of −174.33 and −132.79 kJ/...