ZnO Nanopowders Research Articles

Combustion synthesis, characterization and antibacterial properties of pristine ZnO and Ga doped ZnO nanoparticles

Herein, undoped and Ga doped ZnO nanoparticles were prepared using a combustion method. The effect of Ga doping on the structural, optical, surface morphological and antibacterial properties was explored. The hexagonal wurtzite structure and the preferential (101) plane orientation were confirmed by powder X-ray diffraction (PXRD) studies. The Raman active modes of ZnO phase were found using Raman spectral analysis. The occurrence of the functional groups and chemical bonding was affirmed by FTIR spectra. HRSEM images revealed that the spherical shaped particles are agglomerated and contained several voids. The antibacterial efficacy of the prepared nanoparticles was examined against different bacteria viz. Escherichia coli, Klebsiella pneumoniae and Staphylococcus aureus. From this analysis, it is found that the undoped and Ga doped ZnO nanopowders remarkably enhances the antibacterial activity.

Synthesis and comparative study on the structural and optical properties of ZnO doped with Ni and Ag nanopowders fabricated by sol gel technique

In this work we have tried to prepare Ni and Ag doped ZnO nanopowders using the sol gel technique. The influence of Ni and Ag (1, 3 and 5 mol.%) on the crystalline structure and optical properties of ZnO was investigated. The samples were characterized by XRD, FTIR and UV–visible spectrophotometer. XRD patterns confirmed the wurtzite formation of doped and undoped ZnO nanopowders. The average crystallite sizes of the prepared samples found from XRD were 19 nm for undoped ZnO, from 17 to 22 nm for Ni-ZnO and from 19 to 26 nm for Ag-ZnO. The average crystallite size of Ag-ZnO increased with increasing Ag contents. Different optical properties of Ni-ZnO and Ag-ZnO nanopowders were observed for different Ni and Ag content. The band gaps of Ni-ZnO and Ag-ZnO nanopowders were lower than that of the undoped ZnO (3.1 eV). The band gaps of Ag-ZnO were lower than that of Ni-ZnO. The optical properties of ZnO were enhanced by Ni (mol.%) in the UV region and by Ag (3 and 5 mol.%) in the visible region.

Photoluminescence in gas of (Ca) Mg-doped ZnO nanopowders

The researches structural, morphological and photoluminescent properties of zinc oxide nanopowders doped by Mg and Ca obtained using pulsed laser reactive technology is carried out. Electron microscopy and X-ray diffractometry were conducted to determine the structure, shape, and size of the nanoparticles. Investigation of the peculiarities of photoluminescence in different ambient of Ca- and Mg-doped ZnO nanopowders was carried out. The decomposition of luminescence spectra into elementary bands shows the presence of four elementary peaks. The most intense two bands in visible region which are sensitive to ambient gas, a blue-band centered at 430 nm and stronger in intensity the band around 520 nm. The influence of the impurity and the different ambient on the redistribution of elementary luminescence bands intensities was investigated. That can be used in the gas sensors. The visible emissions observed may be ascribed to the intrinsic defects in particular oxygen vacancies. Large surface area and surface defects are the most important variables to determine the sensory properties of ZnO nanopowders and making them are the most favorable material for gas sensors.

Structural, microstructural and photocatalytic degradation of methylene blue of zinc oxide and Fe-doped ZnO nanoparticles prepared by simple coprecipitation method

Nanoparticles of ZnO doped with Fe (0.00, 0.02, 0.05 and 0.10) were prepared by chemical co-precipitation method. The effect of iron doping on the structural, morphological and optical properties of ZnO nanoparticles was examined by X-ray diffraction (XRD), Scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR) and UV–Visible spectroscopy. The XRD analysis revealed the single-phase of the as-made and Fe-doped ZnO nanoparticles. SEM images showed the formation of aggregates of small individual nanoparticles of various sizes. FTIR analysis indicated the existence of distinct characteristic absorption peaks at 447 cm−1 for Zn–O stretching mode with some changes in the intensities. UV–Visible measurement revealed a reduction in the energy gap with increasing Fe concentration, which is generally due to increasing mesh parameters. The photocatalytic activity of Zn1-xFexO was evaluated by analyzing the degradation of methylene blue (MB). The presence of iron from 2% to 10 at% in the ZnO nanopowder was found to decelerate the photocatalytic process.

Effect of the Addition of Cerium Acetylacetonate on the Synthesis of ZnO Nanopowder

Effect of the Addition of Cerium Acetylacetonate on the Synthesis of ZnO Nanopowder

Synthesis, characterization and application of a bio-derived ZnO nano-powder from spinacia oleracea leaf extract for the removal of BOD and COD from tannery wastewater

Biochemical Oxygen Demand (BOD) and Chemical Oxygen Demand (COD) as biological and chemical pollutants of wastewater are renowned environmental problems. A study of the performance of BOD and COD degradation via adsorption was undertaken using Bio-derived ZnO nanopowder (ZnO-NP), synthesized using leaf extract of Spinacia oleracea, and Zn (NO3)2 at 500 0C, following a simple and green approach. XRD, SEM, FTIR, EDS and BET analysis were used to characterize the nano-adsorbent. EDS spectrum recorded elemental weight compositions of 67.33% and 32.67% for Zn and O, while the FTIR absorption peaks revealed the presence of Zn-O–H and Zn-O. Surface area analysis revealed the mesoporous structure of the ZnO-NPs. The reduction efficiency of the ZnO-NPs was evaluated in the presence of raw tannery wastewater by application of treatment time and adsorbent dosage as parametric factors; results obtained were compared to environmental regulatory limits (WHO and NESREA). Contact times reported removal efficiencies of 81.5-90.8 % and 12.8-50 % for BOD and COD, while adsorbent dosage-influenced BOD and COD removal at an optimum contact time of 30 minutes was found to be 79.2 - 97.5 % and 27.8 to 55.6 % respectively. This study reveals that ZnO nanopowder is better applied as BOD reductants over COD for spent tan liquor.

Antibacterial and Photocatalytic Properties of ZnO Nanoparticles Obtained from Chemical versus Saponaria officinalis Extract-Mediated Synthesis.

In the present work, the properties of ZnO nanoparticles obtained using an eco-friendly synthesis (biomediated methods in microwave irradiation) were studied. Saponaria officinalis extracts were used as both reducing and capping agents in the green nanochemistry synthesis of ZnO. Inorganic zinc oxide nanopowders were successfully prepared by a modified hydrothermal method and plant extract-mediated method. The influence of microwave irradiation was studied in both cases. The size, composition, crystallinity and morphology of inorganic nanoparticles (NPs) were investigated using dynamic light scattering (DLS), powder X-ray diffraction (XRD), SEM-EDX microscopy. Tunings of the nanochemistry reaction conditions (Zn precursor, structuring agent), ZnO NPs with various shapes were obtained, from quasi-spherical to flower-like. The optical properties and photocatalytic activity (degradation of methylene blue as model compound) were also investigated. ZnO nanopowders’ antibacterial activity was tested against Gram-positive and Gram-negative bacterial strains to evidence the influence of the vegetal extract-mediated synthesis on the biological activity.

Structural, optical and magnetic properties of Cd doped ZnO nanomaterials for optoelectronic device application

Cd-doped ZnO nanopowder is synthesized by solid-state reaction. XRD pattern shows a sharp pinnacle at θ = 36° which corresponds to (101) plane. Cd-doped ZnO powder shows a little aggleromation indicating that each grain is made of semicrystalline nature with little humps. FTIR shows a high intense broad IR band at 4350 cm−1 corresponding to the O–H stretching vibration. Raman studies clearly shows that the relays of two different peaks which are observed at 315 and 531 cm−1. Impedance plots state that the decrement in Z′ with expanding recurrence might be because of the increment of the AC conductivity. Dielectric behaviour occurs due to the large formation of grains associated with host lattice. Photosensitivity is found to be as high as 86% at input power of 120 mW. From the optical studies, the bandgap energy is measured and it is found to be 3.15 eV. Photoluminescence studies reveal that the sharp peak tends to move so wide as luminescent range changes from red to blue. The peak which has been seen at 631 nm indicates the green. EPR range demonstrates that Cd particles are in mutilated octahedral sties. The magnetic properties lie in the sample with the Cd fixation expands and the molecules can come close to each other and forms the clusters. These results suggest that these materials can be used for optoelectronic and luminescent device applications.

Vermiwash-derived enzyme-activated ZnO nanomaterial towards two cascading applications: enhanced photocatalysis and effective irrigation

This study focuses on the preparation of enzyme-activated zinc oxide nanomaterial using vermiwash via a simple soft chemical method. This vermiwash––an aqueous extract obtained from vermin reactor––is produced using earthworm, Eudrilus eugeniae, cow dung and leaf litter. The prepared nanoproduct was used to decompose toxic dye molecules through photocatalysis. The enzymes present in the vermiwash (like amylase, phosphatase, urease and protease) are found to be inherited by the prepared nanoproduct as well as the photocatalytically treated water. The quantitative study of enzymes shows that the quantity of enzymes present in the nanoproduct as well as in the photocatalytically treated water increases as the proportion of vermiwash used in the starting solution increases. This increase in the quantity of enzymes causes an increase in the photocatalytic efficiency of the nanoproduct. The photocatalytically treated water which consists of enzymes can be used as a potential candidate for effective irrigation. Thus, the vermiwash-activated ZnO nanopowder prepared in this study shows a two linear cascading applications. The results of the studies on enzymes, photocatalysis, XRD, SEM and FTIR are appropriately correlated with one another to address the enhancement in the photocatalytic activity of the prepared nanomaterials and the underlying mechanism.

The optical and photo-electrochemical characterization of nano-ZnO particles and its application to degradation of Reactive Blue 19 under solar light

To assess its photocatalytic activity under sunlight, ZnO nano powder with crystallites sizes in the range (18–29 nm) was synthesized by decomposition from nitrate (ZnO-Nit) and acetate (ZnO-Ac) precursors by one-step calcinations. The powders were characterized by X-ray diffraction, transmission electron microscopy and Fourier-transform infrared spectroscopy. The optical band gap of ZnO-Ac, determined from the diffuse reflectance, was found to be 3.23 eV and the transition is directly allowed, due to the charge transfer O2−: 2p → Zn2+: 4s. The capacitance-potential (C−2 – E) characteristic plotted at pH ∼7 shows n type behaviour with a conductionband (−0.42 VSCE), made up of Zn2+: 4s orbital and positive of the O2/O2 level and a valence band (2.81 VSCE) deriving mostly from O2−: 2p orbital whose potential is less anodic than the OH/H2O level. So, ZnO was successfully used for the degradation of the Reactive Blue 19 (RB 19) a hazardous dye, by both radicals O2−and OH under solar light. Indeed, RB 19 is a vinylsulphone dye, difficult to eliminate by chemical oxidation because its anthraquinone structure is highly stabilized by resonance. The best photoactivity occurs over ZnO-Ac owing to its large active surface area (59 m2 g−1). The oxidation obeys a zero order kinetic with a rate constant of 7.3 × 10−3 mol L−1 min−1. The elaborated material showed an outstanding recyclability.

Biophysical Characterization of Thin Films of Zinc Oxide Prepared by Sol-Gel

In this research, ZnO nano-powder was used, and the work was in two biological and physical parts. Where the work of the first part was to examine the effect of ZnO powder on Staphylococcus aureus, and the result of inhibition was 100%. As for the second part, the preparation of a thin film by the Sol-Gel method, where thin films were deposited on glass, the structural properties and topography of the surface were studied. The prevailing trend (101). Also, the results of the atomic force microscopy (AFM) tests showed that the resulting granular size of the prepared and annealed films with a temperature (400 ° C) was less than 100 nm, wherein an anti-bacterial nanoscale S. aureus was made.

Gallium Concentration Optimisation of Gallium Doped Zinc Oxide for Improvement of Optical Properties

Abstract The near-band luminescence of doped ZnO is promising for advanced scintillators; however, the dopant type and concentration effects require a detailed study. Undoped and Ga-doped ZnO nanopowders were prepared by a microwave-assisted solvothermal method and the gallium concentration effect on luminescence properties was studied. The near-band luminescence peak position dependence on gallium concentration was observed. Near-band luminescence intensity versus defect luminescence intensity ratio was explored for different gallium concentrations and the optimal value was determined. Samples were prepared with dopant concentrations between 0.2 and 1.5 at%, XRD analysis confirmed that samples contained only zinc oxide hexagonal wurtzite phase. The results of the research showed that ZnO:Ga containing 0.9 at.% gallium was promising for scintillators.

Band Gap Reduction and Petal-like Nanostructure Formation in Heavily Ce-doped ZnO Nanopowders

Band Gap Reduction and Petal-like Nanostructure Formation in Heavily Ce-doped ZnO Nanopowders

Antibacterial and Optical Properties of Mn Doped ZnO Nanopowders Synthesized via Spray Drying and Subsequent Thermal Decomposition

Mn doped ZnO nanopowders with homogenous particle distribution were synthesized using spray drying and thermal decomposition dual methods. Synthesis was carried out in spray drying slurry containing zinc acetate powders followed by calcining the as-prepared powders at 300, 400, and 500oC. Mn doping was achieved by adding manganese (II) acetate at different concentrations between 0.01-0.05 M during the synthesis. The obtained powders were characterized by a variety of characterization techniques. The results of phase analysis revealed that Mn-doped ZnO nanopowders having a single hexagonal structured ZnO phase. According to the results of microstructural and UV-vis characterizations; morphologies and optical properties of the Mn-doped ZnO nanopowders were affected by Mn doping. Furthermore, the results of this study exhibited that the addition of Mn have a significant influence on the antibacterial performance of the synthesized ZnO nanopowders.

Photocatalytic Activity of Zinc Oxide Nanoparticles Prepared by Laser Ablation in a Decomposition Reaction of Rhodamine B

The development of the routes for synthesizing photocatalysts and the methods for investigating their properties is very appealing for applications in ecology and renewable energy production. Zinc oxide is one of the promising photocatalytic materials. In this study, ZnO nanopowders are produced by pulsed laser ablation (Nd:YAG laser, 1064 nm, 7 ns) in water and air, followed by their heat treatment. The structure and composition of the resulting powders are examined using transmission electron microscopy, X-ray diffraction, and differential scanning calorimetry. The nature of the defect states of nanoparticles is investigated using fluorescence spectroscopy. Their photocatalytic activity is tested during photodegradation of Rhodamine B under excitation by the broadband visible and UV-visible light. The influence of the composition and morphology of zinc oxide and the nature of defect states on its photocatalytic activity is discussed.

Nanocrystalline Zn2SnO4/SnO2: Crystal structure and humidity influence on complex impedance

Nanocrystalline Zn2SnO4/SnO2 powder was obtained by a solid state reaction of ZnO and SnO2 nanopowders mixed in the molar ratio 1:1. The phase composition of the obtained powder was studied by XRD and Raman spectroscopy, morphology and texture were characterized by FESEM, TEM, BET and Hg porosimetry, while XPS and FTIR spectroscopy were used to determine the surface chemistry. The influence of humidity on complex impedance was monitored on bulk samples in the relative humidity (RH) range 30–90% in a climatic chamber in the frequency range 42 Hz- 1 MHz at working temperatures of 25 and 50 °C. Change in RH had a significant influence on impedance reduction, especially noticeable in the lower frequency range, indicating potential application of this nanocomposite as a humidity sensing material. Increase in RH led to an increase in AC conductivity that changed with frequency according to the Jonscher power law. The frequency exponent decreased with increase in RH and sample temperature indicating that the correlated hopping barrier model is the dominant conduction mechanism. Complex impedance was analyzed using an equivalent circuit consisting of a parallel resistance and constant phase element, showing the dominant influence of grain boundaries at both working temperatures (25 and 50 °C). The resistance decreased, while the capacitance and relaxation frequency increased with increase in RH. At high humidity an added Wartburg element enabled modeling of the charge diffusion process.

Facile Use of ZnO Nanopowders to Protect Old Manual Paper Documents

One of the main problems faced by libraries, archives and collectors is the mold degradation of the paper-based documents, books, artworks etc. Microfungi (molds) emerge in regular storage conditions of such items (humidity, usually over 50%, and temperatures under 21 °C). If the removal of the visible mycelium is relatively easy, there is always the problem of the subsequent appearance of mold as the spores remain trapped in the cellulosic, fibrillary texture, which acts as a net. Moreover, due to improper hand hygiene bacteria contamination, old books could represent a source of biohazard, being colonized with human pathogens. An easy and accessible method of decontamination, which could offer long term protection is therefore needed. Here, we present a facile use of the ZnO nanopowders as antimicrobial agents, suitable for cellulose-based products, conferring an extended antibacterial and anti-microfungal effect. The proposed method does not adversely impact on the quality of the cellulose documents and could be efficiently used for biodegradation protection.

Immobilization of Photocatalytic ZnO Nanopowders Using Anodized Nanoporous Alumina Substrates

Nanoporous Al₂O₃ substrates with an average pore size of about 150 nm were prepared via anodization of Aluminum plates. Depending on the anodization condition, the surface area of the anodized Al₂O₃ was increased more than six-fold. Solution-combusted ZnO nanopowders were prepared as a function of fuel/oxidant ratios. At a fuel/oxidant ratio of 0.8, ZnO powder showed excellent powder characteristics such as average particle sizes of 30 nm and spherical shape. Electrical properties of SCM ZnO nanopowders with different fuel/oxidant ratios were investigated by Hall measurement. The carrier concentration of SCM ZnO nanopowders at the fuel/oxidant ratio of 0.8, was the highest, three-fold higher than that of any commercial ZnO powders. Using spray coating, these nanopowders were coated onto Al₂O₃ substrates for immobilization. To evaluate the photo-catalytic effect, Ag ions were removed from the wastewater via photocatalysis. The photocatalytic efficiency with the SCM ZnO nanopowders on nanoporous Al₂O₃ substrates was 2.5-fold higher than that with the SCM ZnO nanopowders on normal Al₂O₃ substrates. However, commercial zinc oxide powders did not show any photocatalytic phenomena. The large difference in photocatalytic efficiency was probably attributed to the characteristics of SCM ZnO nanopowder and the large surface area of anodized Al₂O₃.

Utilization of Zinc Oxide Nanopowder for Photocatalytic Removal of Pb++ Ions from Aqueous Wastewater.

Nanometer-sized zinc oxide powders were prepared with a "solution-combustion method (SCM)." This method used zinc oxide nanopowder as a semiconductor oxide catalyst to initiate light-induced redox reactivity in the presence of 150 ppm aqueous lead-ethylenediaminetetraacetic acid solution (Pb-EDTA) for photocatalysis under UV illumination. Removal rates of lead ions in the aqueous Pb-EDTA solution using SCM ZnO powder were compared with those of two other titanium dioxide photocatalysts, P-25 TiO₂-powder (Degussa) and rutile TiO₂ powder, prepared via a homogeneous precipitation process at low temperature (HPPLT). Using SCM ZnO nanopowder, complete removal of lead ions from the aqueous Pb-EDTA solution was observed within 25 min after UV irradiation. However, HPPLT TiO₂ powder and P25 TiO₂ powder took almost 45 and 65 minutes to completely remove the lead ions, respectively. Thus, lead ions removal efficiency of SCM ZnO nanopowder is at least twice higher than the efficiency of the other two titanium dioxide photocatalysts investigated.

CLEAN UP OF MALACHITE GREEN DYE IN AQUEOUS SOLUTION USING ZnO NANOPOWDER

Malachite green dye has been known to have toxic carcinogenic characteristics and potential health risks for humans even at low concentrations. Hence, it is very vital to remediate the dye before discharge into water bodies or water treatment systems. Thus, this article demonstrated the removal of cleanup of malachite green (MG)dye from the aquatic phase using ZnO nanopowder. In this work batch adsorption experiments were accomplished as a function of contact time, pH, and initial dye concentration to study the efficiency of ZnO nanopowder on dye removal (MG). The obtained nanopowder was characterized using various techniques XRD, FTIR, SEM and EDX. The results shown that the maximum absorbed value was 233.16 mg / g. The findings show that ZnO nanopowder have fast contact time and initial concentration absorbing characteristics in dye removal. The maximum capacity of sorbent was found to be 246.36 mg. Furthermore, the study revealed that ZnO nanopowder is an effective sorbent for cleanup of malachite green dye in aqueous solution when comparing with other adsorbent materials. The Adsorption and kinetics parameters of the maximum capacity of sorbent and correlation coefficient showed that the data were well fitted the to the Langmuir isotherm R2 of 0.923 models and pseudo-second-order kinetic model with R2 of 0.994 respectively.