Size Of Zinc Oxide Nanoparticles Research Articles

Influence of post-annealing temperature on the morphological, structural and optical properties of spin coated zinc oxide thin films

In this study, zinc oxide films were fabricated on quartz glass substrate using spin coating technique with 2 molar of zinc oxide in organic solvent as starting materials. The fabricated sample was post-annealed at different temperature from 350 °C to 750 °C for 60 minutes. The energy dispersive x-ray spectroscopy (EDS) confirmed that zinc oxide coating film was fabricated on the quartz glass substrate. The crystallography of zinc oxide films were analyzed by X-ray diffraction (XRD). The crystallite size of zinc oxide nanoparticles was determined from the full-width at half maximum (FWHM) of XRD peaks using Debye-Scherrer’s equation and showed that the zinc oxide films had highly crystalline quality in hexagonal wurtzite crystal structure. The morphological property of films was observed by scanning electron microscopy (SEM). Surface morphology of films shows regularly spread all of zinc oxide films. The optical property of various zinc oxide films was measured using UV-Visible spectrophotometer.

Fabrication of the light and perspiration stability enhancer for the reactive azo‐dyes based on amino silicon oil containing zinc oxide nanoparticles

In this research work, a light and perspiration stability enhancer for the reactive azo-dyes based on amino silicon oil (ASO) containing zinc oxide nanoparticles (ZnO-NPs) was fabricated. The fabricated samples were characterised by Fourier transform infrared spectroscopy, and the microstructural morphologies of cotton fabrics were observed by scanning electron microscopy. The light and perspiration stability was represented by the colour difference value (ΔE CMC), and the light stability was calculated by the ultraviolet protection factor (UPF) value. The experimental results indicated that the ZnO-NPs dramatically improved the light and perspiration stability of all the reactive azo-dyes; the size of ZnO-NPs was decreased by the addition of the coupling reagent, [γ-(2,3-epoxypropoxy)propyl] trimethoxysilane (KH-560), resulting in the significant improvement of the light and perspiration stability. However, the ASO accelerated the yellowing of reactive azo-dyes due to its easy oxidation of activated hydrogen atoms, especially under high temperature. Further study disclosed that the fluoride-ASO with less activated hydrogen atoms significantly improved the light stability.

Surfactant Assisted Sonochemical Synthesis and Characterization of Gadolinium Doped Zinc Oxide Nanoparticles.

Pure and Gd doped Zinc Oxide (ZnO) nanoparticles were synthesized by sonochemical method using different surfactants (PVP/CTAB). The nanoparticles were characterized by powder X-ray diffraction (PXRD), fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS), particle size analysis by DLS technique and UV-Visible spectroscopy. The effect of Gd doping and nature of surfactants on crystallite size, morphology and band gap of ZnO nanoparticles have been investigated. In addition to this, the effect of nature of surfactant on amount of dopant inserted in the ZnO lattice was also studied.

The effect of laser environment on the characteristics of ZnO nanoparticles by laser ablation

In this paper, zinc oxide (ZnO) nanoparticles were prepared by laser ablation of Zinc (purity of 99/99 %) target. The effect of solvents, methanol and distilled water on the characterization of ZnO has been investigated. The beam of a Q-switched Nd: Yag laser with the length wave of 1064 nm and pulse duration of 6 ns was used. ZnO nanoparticles which were produced in distilled water and methanol were characterized by transmission electron microscopy, X-ray diffraction (XRD) and the optical absorption spectroscopy–ultraviolet (UV–VIS-IR). The XRD results showed that the ZnO nanoparticles have a hexagonal crystal structure. Different size of ZnO nanoparticles were formed because of different environment of laser pulse generated.

Fabrication and Optical Characterization of Zinc Oxide Nanoparticles Prepared via a Simple Sol-gel Method

In this research zinc oxide (ZnO) nano-crystalline powders were prepared by sol-gel method using zinc acetate. The ZnO nanoparticles were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), ultraviolet-visible (UV-Vis), Fourier transform infra-red (FT-IR) and energy dispersive X-ray (EDX) spectroscopy. The structure of nanoparticles was studied using XRD pattern. The crystallite size of ZnO nanoparticles was calculated by Debye–Scherrer formula. Morphology of nano-crystals was observed and investigated using the SEM. The grain size of zinc oxide nanoparticles were in suitable agreement with the crystalline size calculated by XRD results. The optical properties of particles were studied with UV-Vis an FTIR absorption spectrum. The Raman spectrum measurements were carried out using a micro-laser Raman spectrometer forms the ZnO nanoparticles. At the end studied the effect of calcined temperature on the photoluminescence (PL) emission of ZnO nanoparticles.

Functionalization of zinc oxide (ZnO) nanoparticles and its effects on polysulfone-ZnO membranes

Incorporation of nanoparticles in membranes has recently been reported to lead to enhancement of the membrane performance for various applications. In this study, ZnO nanoparticles were synthesized via sol–gel method using zinc acetate and oxalic acid as starting materials. However, the influence of additive, in this case ethylene glycol (EG), on the size of ZnO nanoparticles produced was investigated. All diffraction peaks of XRD patterns indicated the wurtzite structure and the hexagonal phase of ZnO nanoparticles. Uniform spherical particle sizes with lower sizes and reduced agglomeration were observed when EG was used under the same experimental conditions. The particle size was found in the range of 20–30nm when EG was used as compared to those without EG, which was between 50–60 nm. Dispersion property of the ZnO NPs was further verified by zetasizer analysis. Subsequent incorporation of the smaller size ZnO nanoparticles in membranes has shown improvement in the characteristics and performance of the membranes. Membranes incorporated with ZnO showed improved hydrophilicity and enhancement of membrane performance in terms of permeability, porosity, and rejection ability.

Synthesis of Highly Concentrated ZnO Nanorod Sol by Sol-gel Method and their Applications for Inverted Organic Solar Cells

The effects of the zinc oxide (ZnO) preparing process on the performance of inverted organic photovoltaic cells (OPVs) were explored. The morphology and size of ZnO nanoparticles were controlled, leading to more efficient charge collection from device and higher electron mobility compared with nanospheres. Nanosized ZnO particles were synthesized by using zinc acetate dihydrate and potassium hydroxide in methanol. Also, water was added into the reac- tion medium to control the morphology of ZnO nanocrystals from spherical particles to rods, and NH 4 OH was used to prevent the gelation of dispersion. Solution-processed ZnO thin films were deposited onto the ITO/glass substrate by using spin coating process and then ZnO films were used as an electron transport layer in inverted organic photovoltaic cells. The analyses were carried out by using TEM, FE-SEM, AFM, DLS, UV-Vis spectroscopy, current density-voltage characteristics and solar simulator.

Investigation of UV absorption and antibacterial behavior of zinc oxide containing poly(vinyl alcohol-g-acrylonitrile) (PVA-g-PAN) nanocomposites films

The aim of the present study was to investigate the UV absorption properties of PVA-g-PAN/ZnO nanocomposite films prepared by free radical graft copolymerization of acrylonitrile on to PVA and subsequent in situ precipitation of ZnO nanoparticles into the polymer matrix. The nanocomposites were characterized by various analytical methods such as Fourier transform infrared spectroscopy (FTIR), Raman spectroscopy, Scanning electron microscopy (SEM) and Atomic force microscopy (AFM) etc. The size of the crystallites and extent of crystallinity were ascertained by X-ray diffraction (XRD) analysis. The SEM with Energy Dispersive X-ray analysis (EDX) showed that the ZnO nanoparticles were uniformly dispersed within the host copolymer matrix. The transmission electron microscopy (TEM) results clearly indicated that the size of zinc oxide nanoparticles varied in the range 10–30 nm. The surface morphology and topography of the PVA-g-PAN/ZnO nanocomposite films were investigated using atomic force microscopy (AFM). The UV-absorption properties of so prepared films were also studied using UV-visible absorption spectroscopy. The results showed that the films were capable of absorbing more than 95 % of incident UV radiations. The antibacterial activities of so prepared nanocomposites were determined against the Gram-negative bacterium Escherichia coli and Pseudomonas aerugenosa, and Gram-positive Micrococcus luteus and Staphylococcus aureus by the disc diffusion test method which showed that the antibacterial activity increased with increasing content of ZnO in the film. The prepared nanocomposites were also studied for swelling behavior.

Genotoxicity and DNA Repair Processes of Zinc Oxide Nanoparticles

Two different sizes of zinc oxide nanoparticles (ZnO NP, ≤35 nm and 50–80 nm) were tested in the human lymphoblastoid cell line TK6 to increase our knowledge on their genotoxic potential. The comet assay was the system used, and the results obtained showed that the highest concentration tested (100 μg/ml) for the two selected compounds was genotoxic. The percent DNA in tail obtained after treatment with ZnO NP (≤35 nm) was significantly higher than that of ZnO NP (50–80 nm) at all concentrations tested. To investigate the nature of the induced genotoxic damage, specific enzymes recognizing oxidized DNA bases were used. Treatments with endonuclease III (Endo III) and formamidopyrimidine DNA glycosylase (FPG) demonstrated that only ZnO NP (50–80 nm) were able to induce significant levels of net oxidative DNA damage. Further DNA repair kinetics studies revealed that DNA damage initially induced was removed in approximately 5 h. DNA damage induced by ZnO NP was repaired more slowly than damage following microparticulated ZnO exposure. No marked differences in repair kinetics of both forms of ZnO NP were observed. Evidence indicates that a high proportion of DNA damage induced by ZnO NP (50–80 nm) correlated with induction of oxidative damage, and that both forms of ZnO NP interfere with mechanisms involved in DNA damage repair.

Pulsed electrical discharge synthesis of red photoluminescence zinc oxide nanoparticles

Zinc oxide (ZnO) nanoparticles have been prepared using a pulsed electrical discharge in a liquid medium. The effects of the processing parameters, including liquid media, current, frequency of the electrical discharge and electrode gap distance exert significant effects on the characteristic and properties of ZnO nanoparticles. The synthesized ZnO nanoparticles are characterized using a combination of transmission electron microscopy (TEM), energy dispersive X-ray (EDS) and photoluminescence (PL) spectroscopy. The average size of ZnO nanoparticles varies between 10–25 nm depending on the processing parameters. It is found that an increase in the arc current plays a great role in particle growth and results in a significant increase in average particles size. Both frequency of discharge and electrode gap distance can influence the average particle size and distribution due to the variation in the cooling rate. The PL spectrum for all as-synthesized ZnO nanoparticles exhibits an ultraviolet emission (~3.4 eV) and a red visible emission (~1.98 eV). The blue shift is independent of the average size of the ZnO nanoparticles. However, the intensity of visible emission is significantly enhanced with the decrease of the particle sizes. The porous structure and irregular particle surface are suggested to contribute significantly to the visible red emission.

The Role of Surface Area of ZnO Nanoparticles as an Agent for some Chemical Reactions

Synthesising zinc oxide nanoparticles (ZnO-NPs) to get certain characteristics to be applied in Enhanced Oil Recovery (EOR) is still challenging to date. In this work, the importance of high surface area of ZnO nanoparticles as EOR agent was highlighted. A simulation on density of state (DOS), band structure and adsorption energy of hydrogen and nitrogen gases on the surface of ZnO was carried out; it is observed that from the band structure of the band gap value for ZnO is 0.808ev. For the ZnO, Zn 4s states contribute to conduction band and O 2p states contribute to valence band. ZnO-NPs were synthesised using the sol-gel method by dissolving zinc nitrate hexahydrate in nitric acid and varying the stirring time (1 and 24h) and sintering time (30 and 40 min). A microwave oven was used for annealing ZnO without insulating the samples in any casket. The results show that 30 and 40 min of annealing and stirring for 1 & 24 h influenced the morphology and size of ZnO-NPs. These parameters could be tailored to generate a range of nanoparticle morphology (flask and/with agglomerated nanoparticles in a corn shape) obtained by Field Emission Scanning Electron Microscope (FESEM) and hexagonal crystal, determined by X-ray diffractometer (XRD), with the mean size of 70.5 & 74.9 nm and a main growth at the peak (101). The prepared sample via stirring for 24h and sintering for 40 min was chosen to prepare ZnO nanofluid because it has the highest surface area (BET) among the rest of samples, 0.23 m2/g. 10% of Original Oil In Place (OOIP) was recovered successfully to prove that ZnO is a good candidate to be applied in some chemical reactions. Moreover, it was found that ZnO is a promising catalyst for ammonia synthesis based on the adsorption energy of hydrogen and nitrogen gases (-1.05 and-1.60 kcal/mol respectively).

Preparation, Characterization, and Application of Zinc Oxide Nanoparticles by Sol-Gel Pyrrolysis Method: Influence of Annealing Temperature on Crystalline Phases

Zinc oxide nano-particles were prepared by a sol–gel pyrrolysis technique using zinc acetate as the precursor compound, isopropanol (IP) as solvent and monoethanolamine (MEA) as chelating and structure directing agent. The dried sol treated in different annealing temperatures was analyzed via thermogravimetry analysis (TG-DTG). Zinc oxide nano-particles were characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR) and field emission scanning electron microscopy (FESEM) techniques and their optical properties were also investigated using diffuse reflectance (DRS) spectroscopy. The results showed that the annealing temperature affected the particle sizes of zinc oxide nano-particles and the weight loss occurred at a peak temperature of 315°C corresponding to formation of zinc oxide. The results indicated that 450°C is the optimum calcination temperature to produce effective zinc oxide nano-particles. The XRD results suggested that the zinc acetate were completely converted to zinc oxide above 350°C. The average crystallite size of the zinc oxide nano-particles was analyzed by XRD and estimated to vary from 54 nm to 65 nm. The results of DRS showed optical band gaps of 3.235, 3.211, and 3.215 eV for zinc oxide nano-particles annealed at 350°C, 450°C, and 550°C, respectively.

Synthesis of ZnO nanoparticles from microemulsions in a flow type microreactor

Zinc oxide (ZnO) nanoparticles were synthesized from microemulsions in a microchannel reactor system. The microemulsions provide confined space for the reactants, which is favorable for controllable reaction and nucleation, thus avoiding the formation of large particles. In addition, the microemulsions prevent the deposition of ZnO particles on the wall of the microchannels of the reactor. Three Zn2+ sources (Zn(NO3)2, ZnSO4, and ZnCl2) were tested in the synthesis of ZnO nanoparticles. Among them, Zn(NO3)2 showed best performance, yielding ZnO particles with the smallest average grain size. The effects of Zn2+ concentration, reaction temperature, and feed flow rate on the average particle size of ZnO nanoparticles were investigated. At optimal conditions, ZnO nanoparticles with average size of 16nm were obtained. The synthesized ZnO nanoparticles were characterized by scanning electron microscope (SEM), X-ray diffraction (XRD), UV–vis absorption spectroscopy, and a laser particle size analyzer.

Synthesis and Characterization of Poly(N-Isopropylacrylamide)-Modified Zinc Oxide Nanoparticles

This paper reports a surface functional polymer- poly(N-isopropylacrylamide) (PNIPAM) was grafted on the surface of zinc oxide (ZnO) nanoparticles. It has been demonstrated that Reversible addition fragmentation chain-transfer (RAFT) agent was successfully grafted onto the surface of ZnO. PNIPAM chains were successfully grafted from the surface of ZnO via RAFT process by using RAFT agent immobilized on ZnO. The effect of surface modification on the size, structure, morphology, and properties of ZnO nanoparticles was investigated. The thickness of a PNIPAM monolayer bound to the ZnO core is somewhat larger than the size of the random coil of the corresponding free PNIPAM in aqueous solution, which suggests that the conformation of a PNIPAM chain bound to the ZnO core is extended.

Study of blueshift of optical band gap in zinc oxide (ZnO) nanoparticles prepared by low-temperature wet chemical method

We report synthesis of zinc oxide (ZnO) nanoparticles via wet chemical method using molar solutions of zinc nitrate hexahydrate [Zn(NO3)2·6H2O] and ammonium hydroxide (NH4OH) with polyvinylpyrollidone (PVP) as capping agent. The synthesized ZnO nanoparticles are characterized by X-ray diffraction (XRD) technique and electron microscopy (TEM and SEM with EDX) for compositional analysis and surface morphology. The average crystallite size calculated from XRD pattern has been found to be on the order of 8.5nm. In this work, the hyperbolic band model (HBM) and UV–vis absorption spectra have been utilized to calculate the band gap and nanoparticle size which was proposed by Meulenkamp. It was Meulenkamp who correlated the particle sizes with the wavelength at which the absorption becomes half of that at the shoulder (λ1/2). The optical band gap value of the prepared ZnO nanoparticle is found to be on the order of 3.63eV which indicates the presence of blueshift. In order to compare the size and distribution of ZnO nanoparticles, TEM has been utilized.

Antibacterial and Cytotoxic Response of Nano Zinc Oxide in Gram Negative Bacteria and Colo 320 Human Adenocarcinoma Cancer Cells

Zinc oxide nanomaterials have sought considerable biomedical applications. The varying grain sizes of zinc oxide nanoparticles (ZnO NPs) were prepared by wet chemical precipitation method. Particle size and morphology of the as-prepared ZnO powders were characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), UV-Visible spectroscopy, dynamic light scattering and transmission electron microscope (TEM). The antimicrobial and cytotoxic activity of varying sizes of ZnO NPs was investigated in gram negative microorganisms and in colo 320 human adenocarcinoma cancer cells. The relationship between physico-chemical properties and oxidative stress response in cell viability and toxicology was determined. The zone of inhibition by nanoparticles ranged from 18 mm to 22 mm. The estimated inhibitory concentration (IC50) values for different sizes of zinc oxide nanoparticles were calculated as 156.25 µg.ml-1 for 15 nm ZnO NPs, 191.5 µg.ml-1 for 25 nm ZnO NPs and 225.3 µg.ml-1 for 38 nm ZnO NPs. Varying sizes of ZnO NPs were partially dissolved to Zn species (Zn(dis)) in Roswell Park Memorial Medium (RPMI) and in milli-Q water. Maximum dissolution of Zn species was observed in milli-Q water. According to the results of the present study, mechanisms of action and cellular consequences resulting from varying sizes of ZnO NPs interactions with infectious microbes and cancer cells suggest that particle size not exceeding 25 nm can be further improved with surface functionalization and loading anti-cancer and anti-bacterial agents.

Extracellular synthesis of zinc oxide nanoparticle using seaweeds of gulf of Mannar, India.

BackgroundThe biosynthesis of metal nanoparticles by marine resources is thought to be clean, nontoxic, and environmentally acceptable “green procedures”. Marine ecosystems are very important for the overall health of both marine and terrestrial environments. The use of natural sources like Marine biological resources essential for nanotechnology. Seaweeds constitute one of the commercially important marine living renewable resources. Seaweeds such as green Caulerpa peltata, red Hypnea Valencia and brown Sargassum myriocystum were used for synthesis of Zinc oxide nanoparticles.ResultThe preliminary screening of physico-chemical parameters such as concentration of metals, concentration of seaweed extract, temperature, pH and reaction time revealed that one seaweed S. myriocystum were able to synthesize zinc oxide nanoparticles. It was confirmed through the, initial colour change of the reaction mixture and UV visible spectrophotometer. The extracellular biosynthesized clear zinc oxide nanoparticles size 36 nm through characterization technique such as DLS, AFM, SEM –EDX, TEM, XRD and FTIR. The biosynthesized ZnO nanoparticles are effective antibacterial agents against Gram-positive than the Gram-negative bacteria.ConclusionBased on the FTIR results, fucoidan water soluble pigments present in S. myriocystum leaf extract is responsible for reduction and stabilization of zinc oxide nanoparticles. by this approach are quite stable and no visible changes were observed even after 6 months. These soluble elements could have acted as both reduction and stabilizing agents preventing the aggregation of nanoparticles in solution, extracellular biological synthesis of zinc oxide nanoparticles of size 36 nm.

Effect of Diluents on Crystallite Size and Electronic Band Gap of ZnO Nanoparticles Synthesized by Mechanochemical Processing

This paper presents the characterization results of Zinc Oxide (ZnO) nanoparticles prepared by mechanochemical processing using different moles of diluents. ZnO nanoparticles of different crystallite size were synthesized by milling the precursor powders for 5 hours in a high energy ball mill with Zirconia media. NaCl was added as process control agent (PCA) to control the reaction kinetics, as final particle size of nanoZnO is influenced by the reaction rate. X-ray Diffraction (XRD) data was used to compute and analyze the crystallite size of nanoparticles and also to analyze the progress of reaction during milling process. Field Emission Scanning Electron Microscope was employed to analyze the particle morphology and size distribution of ZnO nanoparticles. Ultraviolet Visible (Uv-Vis) spectroscope was employed to analyze the optical absorption of ZnO nanoparticles. Tauc plots were used to determine the energy gap of the ZnO nanoparticles. Crystallite size values of ZnO nanoparticles are seen to be influenced by the amount of PCA and heat treatment. ZnO nanoparticles with a range of Eg (3.1 to 3.14 eV) were obtained depending on process parameters and an inverse relationship was observed between the crystallite size and the energy gap of the ZnO nanoparticles.

Size dependent nonlinear optical properties of spin coated zinc oxide-polystyrene nanocomposite films

Using simple wet chemical method at room temperature, zinc oxide (ZnO) nanoparticles embedded in polystyrene (PS) matrix were synthesized. The size of the ZnO nanoparticles could be varied by varying the precursor concentration, reaction time and stirring speed. Transparent films of ZnO/PS nanocomposites of thickness around 1μm were coated on ultrasonically cleaned glass substrates by spin coating. The optical absorptive nonlinearity in ZnO/PS nanocomposite films was investigated using open aperture Z-scan technique with nanosecond laser pulses at 532nm. The results indicate optical limiting type nonlinearity in the films due to two-photon absorption in ZnO. These films also show a self-defocusing type negative nonlinear refraction in closed aperture Z-scan experiment. The observed nonlinear absorption is strongly dependent on particle size and the normalized transmittance could be reduced to as low as 0.43 by the suitable choice of the ZnO nanoparticle size. These composite films can hence be used as efficient optical limiters for sensor protection. The much-pronounced nonlinear response of these composite films, compared to pure ZnO, combined with the improved stability of ZnO nanoparticles in the PS matrix offer prospects of application of these composite films in the fabrication of stable non-linear optical devices.

Certain investigations on the effect of nano metal oxide finishes on the multifunctional characteristics of cotton fabrics

The performance of ultraviolet protection, antimicrobial activity, soil release action and self-cleaning characteristics of nano zinc oxide (ZnO) with acrylic binder were assessed on the cotton fabric using pad-dry-cure method. Different precursors such as zinc chloride and zinc nitrate were used to synthesize nanoparticles by wet chemical technique. The synthesized nanoparticles were then characterized using Fourier transform infrared spectroscopy, particle size analyser, powder X-ray diffractometry and scanning electron microscopy. The nano ZnO finished cotton fabrics were tested for ultraviolet protection factor, antimicrobial activity, soil release action and self-cleaning action. The wash fastness of nano zinc oxide (ZnO) finished cotton fabrics after 5th, 10th, 15th and 20th washes were assessed. Also the ultraviolet protection factor values, percentage reduction in bacteria and soil release percentage in each washing stage are reported. The self-cleaning activity was assessed for 12, 24and 48 h duration by exposing 6% of coffee stain on the specimen fabrics to sunlight. The zinc oxide nanoparticle size of 24 nm was obtained from synthesis of zinc chloride as a precursor, and another nanoparticle size of 38 nm were obtained from synthesis of zinc nitrate as a precursor. The smaller nanoparticles (24 nm) show better results in terms of antimicrobial activity, soil release and self-cleaning action. In case of ultraviolet protection function, it was found that the fabrics treated with 38 nm nanoparticles exhibit higher ultraviolet protection factor values than the fabric treated with 24 nm nanoparticles. The durability of the imparted functions was in the range 25–38 washes for antimicrobial activity, soil release action and ultraviolet protection, respectively.