Zinc Precursor Research Articles

Hydrothermal Synthesis of ZnO Nanoflowers: Exploring the Relationship between Morphology, Defects, and Photocatalytic Activity

Two forms of flower-like ZnO nanostructures were synthesized using hydrothermal methods at various growth times/temperatures and zinc precursors. The morphology, structure, chemical composition, and optical properties of these ZnO nanoflowers were studied using a scanning electron microscope (SEM), X-ray diffraction spectroscopy (XRD), X-ray photoelectrons spectroscopy (XPS), Raman spectroscopy, and UV–Vis spectroscopy. The SEM images revealed two forms of flower-like nanostructures, namely lotus- and tulip-like flower ZnO nanostructures. The XPS analysis revealed the oxidation state of the Zn and O elements, as well as the presence of OH groups on the surface of the lotus-like flower ZnO nanostructure. The XRD results revealed less crystallinity of the lotus-like ZnO nanoflowers (NFs) compared with the tulip-like ZnO NFs. The XRD results revealed the presence of Zn (OH)2 in the ZnO NFs. The Raman results confirmed less crystallinity of the lotus-like ZnO NFs. The estimated optical bandgap was 2.92 and 3.0 eV for the tulip- and lotus-like ZnO NFs, respectively. The tulip-like ZnO NFs showed superior photocatalytic degradation of methylene blue dye, verified via UV–Vis radiation, compared with the lotus-like ZnO NFs, which show the impact of the structure defects and OH- impurities on the photocatalytic performance of ZnO nanoflowers.

The Application of Ultrasound Pre-Treatment in Low-Temperature Synthesis of Zinc Oxide Nanorods

Zinc oxide, due to its unique physicochemical properties, including dual piezoelectric and semiconductive ones, demonstrates a high application potential in various fields, with a particular focus on nanotechnology. Among ZnO nanoforms, nanorods are gaining particular interest. Due to their ability to efficiently transport charge carriers and photoelectric properties, they demonstrate significant potential in energy storage and conversion, as well as photovoltaics. They can be prepared via various methods; however, most of them require large energy inputs, long reaction times, or high-cost equipment. Hence, new methods of ZnO nanorod fabrication are currently being sought out. In this paper, an ultrasound-supported synthesis of ZnO nanorods with zinc acetate as a zinc precursor has been described. The fabrication of nanorods included the treatment of the precursor solution with ultrasounds, wherein various sonication times were employed to verify the impact of the sonication process on the effectiveness of ZnO nanorod synthesis and the sizes of the obtained nanostructures. The morphology of the obtained ZnO nanorods was imaged via a scanning electron microscope (SEM) analysis, while the particle size distribution within the precursor suspensions was determined by means of dynamic light scattering (DLS). Additionally, the dynamic viscosity of precursor suspensions was also verified. It was demonstrated that ultrasounds positively affect ZnO nanorod synthesis, yielding longer nanostructures through even reactant distribution. Longer nanorods were obtained as a result of short sonication (1–3 min), wherein prolonged treatment with ultrasounds (4–5 min) resulted in obtaining shorter nanorods. Importantly, the application of ultrasounds increased particle homogeneity within the precursor suspension by disintegrating particle agglomerates. Moreover, it was demonstrated that ultrasonic treatment reduces the dynamic viscosity of precursor suspension, facilitating faster particle diffusion and promoting a more uniform growth of longer ZnO nanorods. Hence, it can be concluded that ultrasounds constitute a promising solution in obtaining homogeneous ZnO nanorods, which is in line with the principles of green chemistry.

Hydrothermal growth of Zn2GeO4 nanorods for optical and (Photo)Catalytic applications: An experimental and theoretical study

From the material design perspective, we reported a systematic investigation based on theoretical and experimental approaches to explore the physical properties of Zn2GeO4 nanorods prepared by hydrothermal method with different zinc precursors for optical and (photo)catalytic applications. All ZGO samples exhibited uniform nanorod morphology with high purity and crystallinity. A negative zeta potential ranging from −13 mV to −16 mV have been observed for these nanorods. Bandgap values indicated variations among samples synthesized with different precursors. The photoluminescence and photocatalytic activities for these nanorods, have been attributed to the presence of oxygen vacancies on the Zn2GeO4 surfaces. Experimental evidence suggests that these surface defects favor the formation of hydroxyl radicals identified as primary reactive oxygen species responsible for the methylene blue photodegradation. Toxicity testing of photocatalytic residues showed minimal phytotoxic effect on lettuce seed (Lactuca sativa) germination. Additionally, Zn2GeO4 was utilized as an acid catalyst for synthesizing isoxazol-5(4H)-ones, resulting in an increase in the yield from 69 % to 92 % by using this catalyst in multicomponent reactions. Lastly, the theoretical efforts outlined in the study aim to enhance the comprehension of the material design with well-defined morphology using realist theoretical models for the Zn2GeO4 nanorods for the first time.

Polyvinylpyrrolidone mediated electrospun ZnO-ZnFe2O4 composite nanofibers for removing malachite green from water

This study explores the application of ZnO-ZnFe2O4 composite nanofibers for the adsorption of Malachite Green (MG) dye from water. The composite nanofibers were fabricated using simple polyvinylpyrrolidone (PVP) mediated electrospinning method by changing zinc and iron precursor weight ratio named as Zn–Fe (1-1), Zn–Fe (2–1) and Zn–Fe (1–2). The diameter of 1D nanofibers was found to be 40–60 nm. The formation of hexagonal wurtzite structure of ZnO and cubic spinel structure of ZnFe2O4 was confirmed by XRD and HRTEM analysis. The effects of various parameters such as pH, contact time and initial concentration on the adsorption process were investigated. The Zn–Fe (1-1) nanofibers showed higher adsorption efficiency than other two. The adsorption results demonstrated excellent adsorption performance, with a maximum adsorption capacity of 146.77 mg/g at pH = 7 for Zn–Fe (1-1). Furthermore, the adsorption kinetics and isotherms were analyzed to understand the adsorption mechanism and equilibrium behaviour. It was found that the nanofibers material can be recycled and reused up to five cycles.

Sustainable removal of pigment dye from traditional batik textile wastewater using ZnO photocatalysis

Wastewater management in the textile industry poses significant challenges, especially for small-scale facilities lacking proper treatment systems. As an alternative solution, in-situ wastewater treatment has gained prominence. Presently, solar-driven photocatalytic materials offer a promising avenue for effective wastewater remediation. This study employed a one-step probe ultrasonication method to synthesize ZnO nanoparticles with exceptional photocatalytic properties. Comprehensive optimization was undertaken to achieve ZnO particles with superior photocatalytic performance. The effects of various parameters, including wave amplitude (ranging from 0 to 80 %), ultrasonication time (from 0 to 45 min), and precursor zinc acetate concentration (between 0.1 to 0.3 M), were thoroughly investigated. By carefully controlling these conditions, non-agglomerated ZnO particles significantly improved photocatalytic activity, especially under visible-light conditions, when treating wastewater from the textile industry. The produce particle at 0.1 M in conjunction with maximum ultrasonication time and amplitude, provide more dispersed particle with smaller particle sizes. The photocatalytic process exhibited remarkable efficiency, with up to 98 % of the textile waste degraded within 60 min of reaction time using the ZnO particle produced under this condition. Moreover, this higher photocatalytic activity was supported by the rate of kinetic constant of 0.0365 min⁻¹, representing the pseudo-first-order kinetic. Furthermore, this research highlights the robust reusability of ZnO as a photocatalytic material, which remained stable even after three consecutive cycles. These findings affirm that ZnO particles synthesized through the probe ultrasonication method hold great potential for treating dye-containing textile effluents, providing a sustainable and effective solution for addressing this environmental concern.

Precursor effect on the hydrothermal synthesis of pure ZnO nanostructures and enhanced photocatalytic performance for norfloxacin degradation

The indiscriminate production and use of antibiotics have caused an environmental imbalance. Therefore, advanced oxidative processes such as photocatalysis have been proposed to eliminate the presence of such emerging pollutants. On the other hand, the use of photocatalytic processes requires the development of highly efficient photocatalysts. This paper introduces photocatalysts based on ZnO nanostructures with different morphologies and grown by low-temperature hydrothermal synthesis. The choice of zinc precursor resulted in significant variations in both the morphology and size of the ZnO particles. Morphologies, such as, dumbbell-like structures, nanogranules, and ellipsoidal particles were obtained by altering the zinc precursor in a slightly alkaline medium, and parameters such as photocatalyst dosage, initial concentration of antibiotic Norfloxacin (NOR), and pH in photocatalysis were thoroughly investigated. The reactive species responsible for NOR degradation were photogenerated holes, superoxide radicals, and hydroxyl radicals, with the latter showing a greater contribution. Degradation pathways are also proposed, and intermediate products were identified by LC-MS. Thirteen degradation products, of which six were reported for the first time, were detected. Among the synthesized morphologies, nanogranules exhibited superior photocatalytic activity, achieving 100% NOR degradation after 70 min under UV-C light and excellent reusability after three cycles (97%). The results surpass those from previous studies, since the simple and efficient photocatalysts employed led to shorter degradation times.

Phytofabricated ZnO-NPs mediated by Hibiscus tiliaceus leaf extract and its potential as a diosgenin delivery vehicle.

Zinc oxide nanoparticles (ZnO-NPs) have provided promising potential in the biomedical field, including the ability to overcome various health problems. Diosgenin is used to treat multiple health disorders but has very low solubility in water. Using ZnO-NPs as a diosgenin delivery vehicle was expected to increase the solubility of diosgenin, which would affect its bioavailability. This study demonstrates phytofabrication and characterization of ZnO-NPs, loading of diosgenin onto the ZnO-NPs, characterization of the product (ZnO-NPs/diosgenin), and evaluations of diosgenin release. Phytofabrication of the ZnO-NPs was carried out with zinc precursors and Hibiscus tiliaceus leaf extract (HLE) obtained with various extraction solvents. To explore the potential of using the ZnO-NPs as a diosgenin delivery vehicle, diosgenin release from the ZnO-NPs/diosgenin was studied. Based on the X-ray fluorescence (XRF) and X-ray diffraction (XRD) results, ZnO-NPs with high purity have been successfully fabricated. Nano-sized particles were detected using scanning electron microscopy (SEM) and confirmed by transmission electron microscopy (TEM), revealing the smallest particle size of 45.924 ± 27.910 nm obtained from the methanol extract with the zinc acetate precursor. The ZnO-NPs had hexagonal wurtzite and rod-like structures. Diosgenin was successfully added to the ZnO-NPs with loadings of 79.972% for ZnO-HLMEA-D500 (ZnO-NPs/diosgenin produced by doping with a 500 μg mL-1 of diosgenin solution) and 39.775% for ZnO-HLMEA-D1000 (ZnO-NPs/diosgenin produced by doping with a 1000 μg mL-1 of diosgenin solution). The solubilities of diosgenin from ZnO-HLMEA-D500 and ZnO-HLMEA-D1000 were higher than that of free diosgenin, confirming that ZnO-NPs have potential as delivery vehicles for diosgenin and conceivably other water-insoluble drugs.

Photocatalytic degradation of ternary dye mixture using RGO, γ-Fe2O3 and ZnO based binary and ternary nanocomposites

In this work, we report on the improved photocatalytic degradation of a ternary dye mixture of Malachite green (MG), Methyl orange (MO), and Rhodamine B (RhB), by RGO-based binary (RGO/γ-Fe2O3) and ternary (RGO/γ-Fe2O3/ZnO) nanocomposites (NCs). These NCs are synthesized with a green, facile, and rapid microwave irradiation route using Mangifera Indica leaf extract as a reducing agent. X-ray diffraction (XRD) and scanning electron microscopy (SEM) give clear insight into the phase purity and uniform growth of γ-Fe2O3 and γ-Fe2O3-ZnO nanoparticles over the RGO sheets which confirms the reduction of iron and zinc precursors, and graphene oxide via Mangifera to form NCs. The binary and ternary NCs show 100 % degradation of ternary dye mixture in 40 min and 21 min, respectively, under UV irradiation. UV–Visible spectra confirm a reduced energy band gap, 1.96 eV for ternary NCs, and 2 eV for binary NCs as compared to 2.3 eV for γ-Fe2O3. The reduction in band gap and synergism amid RGO and nanoparticles of γ-Fe2O3 and ZnO presents that suppressed charge carrier recombination, enhanced charge carrier lifetime, improved interfacial charge transfer and availability of more active sites in RGO/γ-Fe2O3/ZnO ternary NCs are responsible for highly efficient photocatalytic activities. Reaction kinetics analysis reveals the suitability of the pseudo first-order kinetics and Freundlich model for dye degradation.

Wool fiber as an In situ reducing agent towards ZnO-based surface modified fabric development: Durability assessment in the realm of textile applications

The development of a bio-inspired method to fabricate ZnO nanostructure-modified functional wool fabric represents a substantial challenge in the textile field. This article reports for the first time the use of wool as a reducing agent for the synthesis of ZnO nanoparticles. While previous studies have employed alternative natural reducing agents for surface modification of host materials, this investigation uniquely utilizes the host material, wool, as the reducing agent for in-situ ZnO nanoparticle synthesis. In addition to demonstrating the use of wool as a reducing agent, this literature uniquely reports the durability of the modified fabric, achieved through the use of trimethoxy methyl silane. This silane compound acts as a bridging agent, forming a strong interface between the wool fibers and the synthesized ZnO nanoparticles. This innovative approach enhances the adhesion and stability of the ZnO nanoparticles on the wool fabric, a key aspect that contributes to the overall durability and performance of the modified material. The in situ surface modification process employed a metal oxide precursor (zinc acetate dihydrate), capping agents (hexamethylene tetraamine, sodium carbonate, and sodium sulfate), and a coupling agent (trimethyl methoxy silane). The capping agents were used to control the reaction conditions, while the coupling agent was employed to improve the durability of the surface modification. The impact of three different capping agents on the corresponding synthesis process was assessed, and the findings revealed that the choice of capping agent helped to form ZnO nanoparticles with distinct morphologies. Analytical techniques, such as X-ray diffraction (XRD), scanning electron microscopy (SEM), dynamic light scattering (DLS), and attenuated total reflectance-Fourier transform infrared (ATR-FTIR) spectroscopy, were utilized to characterize the synthesized particles and the treated fabric. The XRD analysis coupled with SEM analysis confirmed the successful formation of ZnO nanoparticles. The ATR-FTIR spectroscopy provided evidence of the formation of Si-O-Zn and Si-O-C bonds, observed at around 920 cm−1 and 1040 cm−1 respectively. These spectroscopic findings indicate that the surface modification involving the silane compound has enhanced the durability of the ZnO-modified fabric. The covalent linkages between the ZnO nanoparticles, the silane compound, and the wool fibers, confirmed by SEM analysis before and after washing cycles, have enabled the durable attachment of the nanoparticles to the fabric surface, even after multiple washing cycles. The results suggest a novel pathway to use wool as a reducing agent for the surface modification of the same material. Detailed mechanistic insights into the surface modification process and the corresponding chemical interactions were also discussed.

Direct Synthesis of Zinc-Blende ZnSe Nanoplatelets.

The distinct optical properties and electronic structures of two-dimensional colloidal nanoplatelets (NPLs) have garnered significant scientific and practical interest. However, concerns regarding the toxicity of cadmium-based NPLs and their limited spectral coverage show the importance of developing nontoxic alternatives. In this study, we devised a new synthetic approach for the direct synthesis of zinc-blende (ZB) ZnSe NPLs. By introducing two different zinc precursors, short-chain metal carboxylate- zinc acetate, and metal halide-zinc chloride, we successfully synthesized two-dimensional ZB ZnSe NPLs. By modifying the reaction parameters, we obtained two different populations of ZnSe NPLs, characterized by the first absorption peak at "343" and "367 nm". Ostwald ripening experiments further confirmed the formation of 2D ZnSe NPLs by the observed discrete growth mechanism. Lastly, we investigated the impact of surface ligands on the excitonic properties of ZB ZnSe NPLs by treating their initially carboxylic acid-capped surface with oleylamine. Remarkably, we observed significant red-shifting in the first excitonic peaks, up to 130 meV, in a reversible manner, demonstrating further tunability of excitonic features in ZnSe NPLs. We anticipate that our findings will serve as a catalyst for further exploration of nontoxic two-dimensional materials, fostering their investigation and application in various fields.

Sphere-shaped ZnO photocatalyst synthesis for enhanced degradation of the Quinolone antibiotic, Ofloxacin, under UV irradiation.

The sphere-shaped zinc oxide (ZnO) photocatalyst was synthesized by the homogeneous precipitation method, using Zn(CH3COO)2·2H2O as a zinc precursor and NH4OH as a precipitating agent. The morphology and crystal structure of the prepared ZnO sample were studied by XRD, SEM, FT-IR, XPS, zetapotential measurements, and a low-temperature nitrogen adsorption-desorption technique. The optical characteristics of ZnO were determined by UV - Vis diffuse reflectance spectroscopy. ZnO photocatalyst performance of up to 100% within 210min was observed in the photodegradation of the ofloxacin antibiotic under ultraviolet (UV) irradiation. The effect of antibiotic concentration, heavy metal ions, and water sources on the photocatalytic activity of ZnO demonstrated both the potential of its application under different conditions, and a good adaptability of this photocatalyst. The photodegradation reaction correlated well with the first-order kinetics model, with a rate constant of 0.0173min-1. The reusability of the photocatalyst was verified after three cycles of use. Admittedly, photogenerated electrons and holes played a key role in removal of the antibiotic. This work showed the suitability of prepared ZnO for antibiotic removal, and its potential use for environmental protection.

Synergistic enhancement of simazine degradation using ZnO nanosheets and ZnO/GO nanocomposites: A sol-gel synthesis approach

This study aims to optimize the synergistic effect in photocatalytic processes by facilitating the accumulation of graphene oxide (GO) layers onto ZnO nanoparticles, thereby achieving close contact between the two materials, leveraging the high surface-to-volume ratio and efficient charge transport pathways inherent in ZnO nanosheets. The performance of ZnO nanosheets in the photocatalytic degradation of Simazine was investigated, with the aim of further enhancing the performance of the best-performing sample through GO decoration. Accordingly, ZnO nanosheets were obtained by the sol-gel method using different concentration of zinc acetate hexahydrate as a zinc source. According to the obtained results, it was observed that the sample prepared with a concentration of 0.44 M zinc precursor salt exhibited the best performance with a degradation rate of 67 %. In order to improve the performance of the sample prepared under this condition, graphene oxide (GO) was integrated into ZnO nanosheets to form a ZnO/GO nanocomposite structure. This composite structure achieved a photodegradation efficiency of 85 % for Simazine. The data obtained showed that the use of GO-based ZnO nanocomposites can improve charge separation, light absorption, charge transport and photo-oxidation of organic pollutants.

Deposition of thin layers of CZTS by sol-gel route via spin-coating

This work focuses on the development of Cu2ZnSnS4 (CZTS) thin films by chemical sol gel via spin-coating for photovoltaic applications. CZTS thin films were developed using metal salts of copper II chloride dihydrate (CuCl2, 2H2O), zinc(II) chloride (ZnCl2), tin II chloride dihydrate (SnCl2, 2H2O), and thiourea (CS(NH2)2) respectively as precursors of copper, zinc, tin and sulphur dissolved in a solvent consisting of a mixture of ethanol and distilled water (30 % ethanol and 70% water). Monoethanolamine (MEA) was used as a stabilising agent. The characterisation techniques used were X-ray diffraction (XRD), Raman spectroscopy and UV–visible spectroscopy (UV–vis). DRX analysis shows that the samples possess the CZTS kesterite phase with a preferential orientation in the (112) direction. This result is confirmed by the Raman spectrum of the samples. Optical characterisation indicates that the layers have a relatively high absorption coefficient (greater than 104 cm−1) in the visible spectrum with a gap energy equal to or close to the optimum value of 1.5 eV.These kesterite-type CZTS samples with good structural and optical properties are likely to fulfil sought-after functionalities as absorber layers for photovoltaic applications.

IGZO thin films deposited by ultrasonic spray pyrolysis: effect of Zn precursor milling and In and Ga concentration

Codoped zinc oxide thin films with indium and gallium (IGZO) were deposited on soda-lime glass substrates by the ultrasonic chemical spray (USP) technique. The influence of the mechanical grinding process of Zn precursor (zinc acetate, AcZn) and the In and Ga concentrations was analyzed. The grinding process was carried out in a planetary ball mill, with a ball:/precursor ratio of 4:1, and a constant rotation speed of 300 RPM. The starting solutions were prepared at a molar concentration of 0.2 and variable In and Ga atomic concentration (1, 1.5, 2, 2.5 and 3 at%). The deposition conditions were kept constant, substrate temperature of 450 °C and deposition time of 7 min. Structural, morphological, optical, and electrical properties were analyzed. From the structural analysis a preferential orientation along the (101) plane for dominant In concentrated IGZO films was observed, whereas for dominant Ga concentrated was the (002) plane. The average optical transmission was in the range of 83–90%, confirming the high transparency of all the deposited films. The bandgap values, Eg, showed slight variations, from 3.43 to 3.53 eV. The best electrical properties were obtained in the IGZO films with an In:Ga ratio of 1.5:1 [IGZO(1.5:1)], evaluated by the figure of merit, 3.50 × 10–3 (Ω/□)−1, calculated for an optical transmission of 86% and a sheet resistance of 63 Ω/□. According to the obtained results, the IGZO thin films deposited by the USP technique, are potentially applicable in the field of optoelectronics, mainly as transparent electrode.

Synthesis of precursors of zinc and magnesium phthalocyaninates substituted by azochromophore fragments and their spectroscopic and luminescence properties

Synthesis of precursors of zinc and magnesium phthalocyaninates substituted by azochromophore fragments and their spectroscopic and luminescence properties

Antibacterial ZnO@CeO2 nanocrystals: Prospective material for control of foodborne pathogens.

Foodborne microbial infections are leading cause of many deadly illnesses. As a result, there is an anticipated need for the development of innovative packaging materials with effective antibacterial potential. This article describes preparation and characterization of innovative ZnO@CeO2 nanocrystals through a facile hydrothermal method, as well as their outstanding antibacterial properties. The ZnO@CeO2 nanocrystals used were prepared using precursors zinc acetate and cerium nitrate at 180°C. Various sophisticated physicochemical parameters were used to assess nanocrystals. The antibacterial activity was examined using minimum inhibitory concentration technique against four major foodborne pathogenic bacteria, namely Staphylococcus aureus (Gram positive), Escherichia coli, Salmonella typhimurium and Klebsiella pneumoniae (Gram negative) at four distinct concentrations (0-400 µg/mL). The in vitro cell compatibility test was done on fibroblasts. According to our findings, the lowest concentration of ZnO@CeO2 nanocrystals limiting development of tested strains is 100 µg/mL. Additionally, the results show that the combination of ZnO and CeO2 can be synergistic, resulting in ZnO@CeO2 nanocrystals with enhanced antibacterial activity. To summarize, unique ZnO@CeO2 nanocrystals with a high surface-to-volume ratio with outstanding antibacterial activity and no harmful impact to mouse fibroblasts were shaped. The ZnO@CeO2 can be utilized to competently suppress microbial growth spoiling the food and could be utilized as economical and efficient future packaging material for food industries.

Zinc‐bis(imino)pyridine Complexes as Catalysts for Intermolecular Amidation of Benzylic C(sp3)−HBond

AbstractEfficient NNN‐pincer type bis(imino)pyridine ligand based zinc(II) catalyzed intermolecular amidation of benzylic hydrocarbons with sulfonamides has been developed. The zinc complexes were synthesized by the reaction of bis(imino)pyridine ligand with zinc(II) precursors such as Zn(OAc)2 ⋅ 2H2Oand ZnBr2. The structure of the bis(imino)pyridine‐Zn(OAc)2 complex was characterized by single crystal X‐ray diffraction. The zinc(II)‐bis(imino)pyridine complexes were utilized as catalysts for the intermolecular amidation of benzylic C(sp3)−H bond in the presence of N‐bromosuccinimide (NBS) as an oxidant. A broad range of substrates delivered the products in moderate to good yields. This protocol provides the synthesis of various amides viaC−H activation.

Synthesis of High Efficient InP Based Quantum Dot by Reactivity Control of Zinc Precursors

Synthesis of High Efficient InP Based Quantum Dot by Reactivity Control of Zinc Precursors

Zwitterionic bifunctional stable zinc complexes as single catalysts for the valorization of CO2 into cyclic carbonates

Bifunctional pyrrole containing nitrogen Schiff base zinc complexes were developed as single catalysts for the solvent free CO2 cycloaddition into epoxides. Four zwitterionic complexes (Zn-N-SB+/X−) were prepared by quaternarization of their neutral zinc precursor (Zn-N-SB) with different alkyl halides. The experimental compound characterization (NMR, IR, HRMS) was completed using the density functional theory (DFT) to obtain optimized structures. All the bifunctional zinc complexes efficiently promoted the solvent free cycloaddition of CO2 into styrene oxide, acting as both, Lewis acid and Lewis base catalyst, to form styrene cyclic carbonate in very good yields (up to 90 %) reaching TOF values up to 257 h−1. Best catalytic activity was noted for the iodine containing zwitterionic species (Zn-N-SB+/I−) that was used in very small loading (0.2 mol%) to enlarge the reaction scope to other epoxides in solvent free conditions, allowing high cyclic carbonate yields in the case of terminal epoxides. The comparison of the catalytic system formed by the neutral zinc complex (Zn-N-SB) combined to an iodine ammonium salt and its derived zwitterionic iodine containing complex (Zn-N-SB+/I−), showed that the bifunctional catalyst is more active. In order to get mechanistic insights, for both catalytic systems, the reaction order was calculated by VTNA (variable time normalization analysis) and the epoxide opening regioselectivity was determined using aniline as nucleophile.

The implementation of ZnS–SnS BM NPs for phenanthrene degradation: An adsorptive photocatalyst approach and its toxicity studies in adult zebrafish

Phenanthrene is a persistent organic pollutant released by numerous industries. The purpose of the study is to construct a batch reactor for phenanthrene degradation using a bimetallic (BM) ZnS–SnS nanoparticle as a photocatalyst. ZnS–SnS BM NPs were used as a photocatalyst, employed from precursors Zinc acetate dihydrate and tin (II) chloride dihydrate, with crystalline cubic-shaped particle sizes. ZnS–SnS BM NPs were utilized in batch adsorption assays to assess the impact of phenanthrene degradation parameters on various PAHs (Polycyclic aromatic hydrocarbons) concentrations, pH levels, and irradiation sources. Adsorption kinetic and isotherm tests revealed that the pseudo-first order kinetic model, pseudo-second order kinetic model, and Langmuir isotherm model all fit effectively with the effective phenanthrene degradation using ZnS–SnS BM NPs. The degraded product were analyzed for GC-MS, revealing that organic pollutant phenanthrene was converted into harmless by-products like n-hexadecenoic acid, oleic acid, and octadecanoic acid. The toxicity of phenanthrene was observed to decrease with an increase in ZnS–SnS BM NPs concentration. ZnS–SnS BM NP concentration of 150 μg/mL, the zone of inhibition values was recorded highest zone of inhibition (19 ± 1.2 mm) against the strains S. epidermis followed by B. cereus and Clostridium spp. Further adult zebrafish were found to be less toxic to ZnS–SnS BM NPs after 96 h of exposure, with an LD50 of 100 μg/L. The toxicity escalated as concentrations increased. Behavior test showed normal swimming, learning, and memory in open tank and T-maze tests, while 100 μg/L showed pausing/frozen time in zebra fish therefore low doses are considered safe. Hence by employing ZnS–SnS BM NPs can be engaged in waste water treatment for PAH degradation.