Zinc Acetate Solution Research Articles

Study of structural and optical properties of low temperature photo-activated ZnO-rGO composite thin film

Zinc oxide-reduced graphene oxide (ZnO-rGO) nanocomposite thin films were fabricated by dip-coating various substrates with a homogeneous dispersion of graphene oxide powder in a sol-gel derived ethanolic solution of zinc acetate and subsequent photo-annealing with deep-ultraviolet radiation. For comparison, ZnO thin films and ZnO-rGO thin films thermally annealed at 500°C were also prepared. The low temperature deep-ultraviolet irradiation resulted in crystallization of ZnO and reduction of graphene oxide which was confirmed by x-ray diffraction and Raman spectroscopy. Moreover, the Raman spectra also revealed that the reduction degree of graphene oxide was highest for deep-ultraviolet irradiated ZnO-rGO thin film. These results show that photo-chemical activation by deep-ultraviolet irradiation provides a low temperature, environment friendly technique to make ZnO-rGO thin films and can be used to fabricate semiconductor-graphene composite thin films on flexible substrates.

Role of growth conditions on optical and electrical properties of fiber structured Zn0.90Cd0.1O thin films

Fiber structured Zn0.90Cd0.1O films were obtained on glass substrate using zinc acetate and cadmium acetate solution through chemical spray pyrolysis method. All the deposited films are polycrystalline with hexagonal wurtzite structure. The average crystalline size of the deposited films were estimated through intensity of diffraction peak corresponding (101) plane, which is observed to increase with increase substrate temperature. The films deposited at 673 and 723 K have fibrous structure irrespective of the precursor concentration. The presence of Cd in the deposited films was confirmed by EDAX. The high transparency around 90% in visible region was observed for the sample deposited at 723 K using 0.0125 M concentration. It is seen that the optical energy band gap varies from 2.85 to 3.05 eV as the deposition temperature is changed from 673 to 723 K. The film deposited using 0.05 M concentration had low Urbach energy values compared to other molar concentrations confirming the minimization of defect states in these samples. With increasing deposition temperature the near band edge peak of photoluminescence spectrum shifted towards shorter wavelengths and in the same spectrum the weak green emission may be due to presence of singly ionized oxygen ion. The estimated activation energy of the deposited films was observed to decrease with increasing temperature and precursor concentration.

Nanoscale electrical properties of ZnO nanorods grown by chemical bath deposition.

Well-aligned zinc oxide nanorod arrays (ZNAs) synthesized using chemical bath deposition were fabricated on a gallium-doped zinc oxide substrate, and the effects of varying the precursor concentrations on the growth and nanoscale electrical properties of the ZNAs were investigated. The as-synthesized ZNAs were characterized using field-emission scanning electron microscopy (FESEM), atomic force microscopy (AFM), conducting atomic force microscopy (CAFM), and scanning surface potential microscopy (SSPM). The FESEM and AFM images show that the growth rate in terms of length and diameter is highly sensitive to the precursor concentration. CAFM and SSPM analyses indicate that when concentrations of both the zinc acetate and hexamethylenetetramine solutions were 30 mM, the coverage percentages of the recordable and conducting regions on the ZNA surface were 48.3% and 0.9%, which is suitable for application in resistive random access memory devices.

Bulk Heterojunction Solar Cell Devices Prepared with Composites of Conjugated Polymer and Zinc Oxide Nanorods

ZnO nanorods (Nrods) with ~20–50 nm lengths were synthesized using an aqueous solution of zinc acetate and glacial acetic acid. Bulk heterojunction solar cells were fabricated with the structure of indium tin oxide (ITO)/polyethylenedioxythiophene doped with polystyrene-sulfonic acid (PEDOT:PSS)/ZnO-Nrods + polymer/electron transport layer (ETL)/Al. Current density-voltage characterization of the resulting cells showed that, by adding an ETL and using polymers with a low band gap energy, the photoactive layer surface morphology and the device performance can be dramatically improved.

Influence of Precursor Solution Concentration on Structure and Magnetic Properties of Zinc Oxide Thin Films

Zinc oxide thin films were deposited on glass substrate at a substrate temperature of 673K by spray pyrolysis method using different concentration of 0.0125M, 0.025M and 0.05M of Zinc acetate solutions. The effect of molar concentrations on structure, surface morphology and magnetic properties of ZnO films were investigated using x-ray diffraction, scanning electron microscopy and vibrating sample magnetometer. All deposited films were polycrystalline in nature with hexagonal wurtzite structure having a preferential growth orientation along (101) plane. An improvement of crystallinity in the deposits with increasing concentration of sprayed solution was noticed. All deposit exhibit fibrous structure which increases with increase of precursor concentration solutions. At room temperature, all deposited films were shown diamagnetic character but when cooled to 5K, they have shown paramagnetic characteristics.

Bio-medically active zinc oxide nanoparticles synthesized by using extremophilic actinobacterium, Streptomyces sp. (MA30) and its characterization

The present study describes the synthesis of zinc oxide nanoparticles (ZnO-NPs) using an extremophilic actinobacterial cell-free extract, supplied with aqueous zinc acetate solution. Crystalline nature, morphological features, and polydispersed nanoparticles size (15–30 nm) were identified by X-ray diffraction (XRD), atomic force and electron microscopic analysis with dynamic light scattering (DLS) study. The interaction between biomolecules and ZnO-NPs was analyzed using Fourier transform infra-red spectroscopy (FT-IR). Furthermore antibacterial, antioxidant activities, and cell viability test of ZnO-NPs were systematically evaluated. The present study opens a new avenue for the actinobacterial synthesis of oxide nanoparticles.

Facile synthesis of glucoamylase embedded metal-organic frameworks (glucoamylase-MOF) with enhanced stability

The self-assembled glucoamylase metal-organic framework (glucoamylase-MOF) was synthesized by facile one-step method within 20min by simply mixing aqueous solution of 2-methylimidazole (160mM), glucoamylase (5mg/mL) and zinc acetate (40mM) at room temperature (28±2°C). The prepared glucoamylase-MOF was characterized by using FT-IR, confocal scanning laser microscopy, XRD and SEM. The robustness and thermal stability of glucoamylase embedded MOF was evaluated in terms of half-life (in the range of 60–80°C) which showed 6 folds increment as against free form. Further, in Michaelis–Menten kinetics studies, glucoamylase entrapped MOF exhibited higher Km value and lower Vmax value as compared to native enzyme. Moreover, the immobilized glucoamylase exhibited up to 57% of residual activity after six consecutive cycles of reuse, whereas it retained 91% of residual activity till 25days of storage. Finally, the conformational changes occurred after the encapsulation of glucoamylase in the interior of MOF, which was analyzed by using FT-IR data analysis tools.

Modified and systematic synthesis of zinc oxide‐silica composite nanoparticles with optimum surface area as a proper H2S sorbent

The main objective of this work is to synthesize high surface area zinc oxide/silica composite nanoparticles via a facile and systematic process. Regarding the importance of surface area in application of such nanoparticles, variation of this factor was studied by change of reaction parameters including concentration of zinc acetate solution, pH, and calcination temperature via Response Surface Method combined with Central Composite Design (RSM‐CCD). Optimum conditions were obtained as a concentration of 0.013 mol · L−1, pH of ∼8.97, and calcination temperature of 541.6 °C. Optimum nanoparticles were characterized by various analyzes such as XRD, BET, AAS, FTIR, TGA/DTA, FESEM, EDS, and TEM. Comparison of two 0.1 g/g (10 wt %) ZnO/Silica samples with the optimum (337 m2 · g−1) and non‐optimum (95 m2 · g−1) surface areas indicated that nanoparticles prepared at the optimum conditions with average diameter of about 18 nm showed a H2S adsorption capacity of about 13 mg per gram of sorbent. This value was higher than that of the non‐optimized sample (6 mg per each gram of sorbent).

Sonochemical zinc oxide and layered hydroxy zinc acetate synthesis in fenton-like reactions

Zinc acetate solution is sonicated at high power in water and in ethanol in the absence and presence of various peroxides. In the absence of peroxides, the products are zinc oxide and layered hydroxy zinc acetate in water and in ethanol, respectively. Layered basic zinc acetate are prepared for the first time using sonochemical methods. The addition of peroxides alters the reaction mechanisms. In water, insoluble peroxides produce zinc oxides while the water soluble peroxide, i.e. hydrogen peroxide, completely destroyed the structure and casted a doubt on the accepted peroxide initiated mechanism of reactions. In ethanol, peroxide addition caused the reaction mechanism to change and some oxide formation is observed. The reaction mechanism is sensitive to water/ethanol amounts as well as the peroxide to zinc ion mole ratio. Thin zinc oxide wafers (ca. 30nm) with band gaps of 3.24eV were obtained.

Investigation of manifestation of optical properties of butterfly wings with nanoscale zinc oxide incorporation

In this work, microstructural and optical characteristics nanoparticles of wings of Tailed Jay (Graphium Agamemnon) butterfly were studied before and after treating it in a precursor solution of zinc acetate and ethanol. We speculate that the butterfly scales are infiltrated with ZnO nanoparticles owing to reduction of Zinc hydroxide under ambient condition. The ZnO butterfly scales so produced were characterised using optical microscopy, UV-Vis reflectance spectroscopy, and electron microscopy etc. From the reflectance spectra, we could see that after treating it in the solution, optical properties vary. We anticipate that this change may be due to the formation of ZnO nanoparticles as well as the loss in periodicity due to the chemical treatments, which could be assessed from the SEM micrographs.

The Use of Quaternary Ammonium Bromides to Control the Microstructure of Zinc Oxide Films Formed Using Aerosol Assisted Chemical Vapour Deposition

A method in which the microstructure of thin films of zinc oxide can be controlled through the use of readily available additives is presented. This paper will discuss the use of a range of tetra-alkyl quaternary ammonium bromides as additives during the aerosol assisted chemical vapour deposition of zinc oxide, synthesised primarily from a solution of zinc acetate in methanol. Using a combination of single and dual source aerosol assisted chemical vapour deposition and analysis using scanning electron microscopy, we will present a range of morphologies, including plates with rough edges, plates with well-defined hexagonal structures, and organised stacks growing perpendicular to the substrate. Powder X-Ray diffraction techniques reveal that films grown in the presence of the additives also display high levels of preferred orientation when compared to zinc oxide films formed in the absence of any quaternary ammonium bromides. We will also demonstrate the influence of additives on the thickness of the films.

Hydration Structures and Water Chemistry at Zirconia-Water Interface

The life cycle of zirconium cladding is a key safety factor and design parameter for higher fuel burnups in pressurized water reactors. The degradation of the metal alloy is primarily attributed to interactions of native oxide with water. Here we probe the detailed interfacial hydration structures at the 8 mol% yttria-stabilized cubic zirconia (YSZ) surfaces as a model system using synchrotron-based high-resolution X-ray reflectivity technique. Interfacial hydration structures in the major crystallographic orientations, (100), (110), and (111), were determined with sub-angstrom resolution and compared with each other to identify common features as well as different surface chemistry effects on the interfacial processes. All three surfaces terminate with significant number of point defects originating from the metal depletion and the intrinsic oxygen vacancies. Water molecules fill those vacancies, forming an ordered, layered structure on the top surface. Above the termination layer on each surface, two additional adsorbed layers form characteristic interfacial hydration structures. The first adsorbed layers likely include metal species based on the observed local densities, whereas the second layers consist of pure water. The current results provide valuable references for future studies of water chemistry effect on the interfacial hydration structure and the high temperature stability test of the zirconia in pressurized water conditions simulating realistic environment in pressurized water reactors of nuclear power plants. We also studied the effect of zinc adsorption on the interfacial hydration structure in zinc acetate solutions. Zinc injection into the reactor coolant system has been known to be effective in reducing the radioactive wastes as well as stabilizing crud oxide layers of the cladding materials. Our X-ray reflectivity data qualitatively reveal that there are obvious hydration structure changes at (100) and (111) surfaces while (110) surface show little changes. The interfacial electron density profiles were derived from the structure factor analysis of the measured reflectivity data. The structure factor analysis indicated an inner-sphere adsorption of Zn2+ layer at YSZ (111)-water interface, while there appeared to be an outer-sphere adsorption of Zn2+ layer at YSZ (100)-water interface. We further confirmed the detailed element specific adsorption profile of Zn2+ ions on YSZ (110) and (111)-water interfaces with resonant anomalous X-ray reflectivity measurements.

Effect of cerium on structural and optical properties of ZnO aerogel synthesized in supercritical methanol

AbstractPure ZnO and Ce-doped (5 at.%) ZnO aerogels were prepared by dissociation of dihydrate zinc acetate and cerium nitrate in methanol, followed by drying in supercritical conditions of the solvent. The concentration of zinc acetate solution and the atomic ratio Ce/Zn were fixed at 0.2 mol/L and 0.05 mol/L, respectively. XRD results showed a hexagonal wurtzite structure of ZnO aerogel crystallites and a formation of a separate second phase of ceria cubic phase with fluorite structure and 7.4 nm in size. The introduction of cerium in the solution had a negative effect on the aerogel crystalline quality. The crystallites size was found to be 16 nm in pure ZnO and 27 nm in Ce-doped ZnO aerogels. The grains of Ce-doped ZnO aerogel had torus shaped morphology with hollow centers, but those of pure ZnO were flattened semispheres. The calculated values of different structural parameters showed that cerium ions introduced into the ZnO lattice occupied interstitial sites and Zn ions substituted Ce ones in ceria lattice during the formation process. FT-IR and UV-Vis absorption spectra have not revealed any particularities due to the presence of cerium atoms in ZnO, indicating that Ce (5 at.%) doping of ZnO crystallites synthesized in supercritical methanol did not strongly affect the optical gap of the semiconductor. Micro-Raman studies confirmed the formation of cubic fluorite structure ceria in ZnO aerogel and showed that Raman active modes of ZnO are amplified with the presence of ceria.

Deposition and characterisation of spray-deposited nanocrystalline Cd1−XZnXS thin films for photovoltaic device applications

Nanocrystalline Cd1−XZnXS thin films (X = 0.2, 0.4, 0.6, 0.8) have been grown on glass substrate by spray pyrolysis technique using equimolar concentration aqueous solution of cadmium chloride, zinc acetate and thiourea. Prepared thin films have been characterised by UV–vis spectrophotometer, X-ray diffractometer, SEM/EDAX analysis and two-point probe set-up. The optical band gap of the films has been studied by transmission spectra in wavelength range 325–600 nm. It has been observed that optical band gap increases with increasing zinc concentration. The X-ray diffraction pattern of films indicated that the films are polycrystalline with hexagonal grain structure. The lattice parameters of prepared Cd1−XZnXS films decrease with increase in zinc content. SEM/ EDAX analysis consolidates the formation of ternary compound. The DC electrical conductivity and activation energy of the films has been measured in vacuum by a two-point probe set-up. It has been observed that the electrical conductivity decreases with increasing Zn concentration in films.

Influence of the spray distance to substrate on optical properties of chemically sprayed ZnS thin films

In this study, zinc sulfide (ZnS) nanostructures with different morphologies were effectively fabricated on glass substrates at 200 °C via spray pyrolysis. The Zn2+ and S2− ions were sourced from aqueous solutions of zinc acetate and thiourea, respectively. The samples were deposited at different spray distances (15, 20, 25, 30 and 35 cm) in order to examine the effect of spray distance on the optical and structure properties of synthesized ZnS nanostructures. Following the deposition procedure, the films were characterized using X-ray diffraction, UV–Vis–NIR spectrometry, photoluminescence (PL) spectroscopy and field emission scanning electron microscopy. The crystallinity and morphology of the cubic ZnS films were found to vary with spray distance, where the average particle size appears to increase with the increasing spray distance. The highest absorption values were obtained for ZnS films crystallized at a spray distance of 30 cm. The PL analysis specified the presence of violet and green emissions, which are attributable to Zn and S vacancies. The band gap of the ZnS films was observed to decrease slightly from 3.82 to 3.30 eV with the increasing spray distance. The results indicate that the spraying distance affects the characteristics of ZnS nanostructures.

Optimize preparation parameters of colon-specific pellets of Angelica Sinensis Radix supercritical fluid extraction with response surface analysis methodology

To prepare pellets of supercritical fluid extraction (SFE) of Angelica Sinensis Radix by using the ionic crosslinking method, and the drug loading and encapsulation efficiency were used as the index to investigate the multiple factors which may impact the drug loading and encapsulation efficiency. Box-Behnken design and response surface analysis method were then taken to optimize the prescription of pellets and study the coating technology. Through the study on the release of pellets in vitro, an optimal coating technology and prescription of colon-specific pellets of Angelica Sinensis Radix SFE were selected and their colon targeting was evaluated. The optimal preparation parameters of pellets were determined as follows： 3% pectin; 4∶1 for pectin/lecithin; 4∶5 for pectin/SFE of Angelica Sinensis Radix; 4% zinc acetate solution as crosslinking agent, blending temperature 35 ℃, crosslinking temperature 35 ℃, crosslinking time 30 min; coating technology： coating material Eudragit FS 30D, 1.5% triethyl citrate and polyoxyethylene sorbitan monooleate（tween-80）, 1.2% monostearin and 15% coating weight gained. The colon-specific pellets of Angelica Sinensis Radix SFE prepared with optimized conditions were almost not released in simulated gastric fluid in 2 h, released less than 20% in simulated intestine fluid in 4 h, and released more than 90% in simulated colon fluid in 6 h, indicating that the colon-specific pellets of Angelica Sinensis Radix SFE had an excellent colon targeting property.

Nanostructured ZnO thin film with improved optical and electrochemical properties prepared by hydrothermal electrochemical deposition technique

Zinc oxide (ZnO) thin films were grown on fluorine-doped tin oxide coated glass substrate by the hydrothermal electrochemical deposition (HTED) route using slightly acidic aqueous zinc acetate solution at 80°C and were characterised by various techniques. The deposited films showed n-type behaviour with improved carrier concentration. The steady state photocurrent densities were found to be 0.4 mA/cm2 (under UV irradiation) and 8 µA/cm2 (under visible light illumination) at zero bias potential. Significant improvement of optical, electrochemical and photoelectrochemical properties of deposited films could be achieved using HTED technique.

Effect of seeding modification of substrate on the growth and UV detection properties of ZnO nanowires

Effect of seeding modification of a glass substrate on the growth of ZnO nanowires and their UV detection properties have been investigated. Seeding functionalization was carried out by two methods including several times dip-coating inside a zinc acetate solution and coating of ZnO on the substrate by sputtering. The functionalized substrates then were used for growth of ZnO nanowires by chemical bath deposition. Various characterizations of the nanowires indicate that the seeding of both methods leads to formation of long nanowires with hexagonal cross section. The photocurrent measurement under UV illumination indicates the superiority of the sputtering pre-seeding due to its better crystalline nanowires and higher quantum efficiency for UV detection.

Dimensionality Alteration and Intra- versus Inter-SBU Void Encapsulation in Zinc Phosphate Frameworks.

4,4'-Bipyridine-N-oxide (BIPYMO, 1), a less commonly employed coordination polymer linker, has been used as a ditopic spacer to bridge double-four-ring (D4R) zinc phosphate clusters to form novel framework coordination polymers. Zinc phosphate framework compounds [Zn4(X-dipp)4(BIPYMO)2]n·2MeOH [X = H (2), Cl (3), Br (4), I (5); dipp = 2,6-diisopropylphenyl phosphate] have been obtained by treating a methanol solution of zinc acetate with X-dippH2 and BIPYMO (in a 1:1:1 molar ratio) at ambient conditions. Framework phosphates 2-5 can also be obtained by treating the preformed D4R cubanes [Zn(X-dipp)(DMSO)]4 with required quantities of BIPYMO in methanol. Single-crystal X-ray diffraction studies reveal that these framework solids are two-dimensional (2D) networks as opposed to the diamondoid networks obtained when the parent unoxidized 4,4'-bipyridine is used as the linker (Inorg. Chem. 2014, 53, 8959). The two types of voids (viz., smaller intra-D4R and larger inter-D4R) present in these framework solids can be utilized for different types of encapsulation processes. For example, the in situ generated 2D framework 2 encapsulates fluoride ions accompanied by a change in the dimensionality of the framework to yield {[(nC4H9)4N][F@(Zn4(dipp)4(BIPYMO)2)]}n (6). The three-dimensional framework 6 represents the first structurally characterized example of a fluoride-ion-encapsulated polymeric coordination compound or a metal-organic framework. The possibility of utilizing inter-D4R voids as hosts for small organic molecules has been explored by treating in situ generated 2 with a series of organic molecules of appropriate size. Framework 2 has been found to be a selective host for benzil and not for other structurally similar molecules such as benzoquinone, benzidine, anthracene, naphthalene, α-pyridoin, etc. The benzil-occluded isolated framework [benzil@{Zn4(dipp)4(BIPYMO)2}]n (7) has been isolated as single crystals, and its crystal structure determination revealed the binding of benzil molecules to the framework through strong π-π interactions.

Fabrication of electrospun ZnO nanofiber-modified electrode for the determination of trace Cd(II)

ZnO nanofibers (ZnO NFs) were fabricated by electrospinning a dimethylformamide solution of zinc acetate containing polyvinylpyrrolidone and polymethylmethacrylate binary polymer matrix, followed by calcination. The obtained ZnO NFs are composed of close-packed ZnO nanoparticles of ca.20nm in diameter. With Nafion acting as adhesive, the ZnO NF coated glassy carbon electrode (ZnO NF/GCE) has been prepared and applied as a new sensing platform for heavy metal determination with square wave stripping voltammetry. The high surface area and the strong affinity to cadmium (Cd) render the ZnO NF/GCE sensitive to Cd ion measurement. The experiment parameters were optimized by the design of orthogonal experiment. Under the optimal conditions, the current response exhibits a good linear relationship with the concentration of Cd(II) ranging from 4.8×10−9 to 1.3×10−6molL−1,with the detection limit of 1.8×10−9molL−1 (S/N>3). The developed sensor has been successfully applied for the determination of Cd(II) in water sample. The simultaneous analysis of Cd(II), Pb(II), Cu(II) and Hg(II) has been demonstrated to be feasible.