Characterization Of ZnO Nanostructures Research Articles

Synthesis, characterization, and photocatalytic activity of ZnO nanostructures

This study investigated the synthesis, characterization of ZnO nanostructures using different precipitating agents in the photodegradation of rhodamine B (Rh B) using scanning electron microscopy (SEM), X-ray diffraction (XRD), fourier transform infrared (FTIR) and UV/Vis spectroscopy and zeta potential measurements. The results indicated the dependence of morphology on calcination temperature and the precipitating agent. The colloidal stability of these nanomaterials is affected with the morphology changed. The photocatalytic results showed that ZnO nanostructures synthesized with NH4OH (98.98%) were more efficient in the degradation of Rh B than ZnO nanostructures synthesized with NaOH (62.68%). This is related to ZnO (NH4OH) nanoparticles should present a higher density of electronic defects than ZnO (NaOH), producing energy levels between the band gaps. These results are potentially associated with a combination of optical and geometric factors that create other paths for the generation of electron-hole pairs in the precipitated ZnO nanocatalyst with different alkaline solutions.

Growth and characterization of ZnO nanostructures on porous silicon substrates: Effect of solution temperature

ZnO nanostructures were grown on porous silicon (PSi) substrate at different solution temperatures (85–100 °C) by using electrodeposition method. Then PSi/ZnO samples were systematically characterized. XRD analysis indicated that crystal quality and polycrystalline nature of ZnO nanostructures increased with temperature. SEM analysis revealed that the structure changed from nanosheets to nanoflowers. Raman and PL analyses proves that the aligned nanostructures exhibited high E2(H) mode of hexagonal ZnO in the range of 430–440 cm−1 and the typical emission peaks in the visible regions. These nanostructures with finely-controlled novel morphologies can be used to fabricate nano-optical devices due to its structural and optical properties.

Synthesis and characterization of ZnO nanostructures with varying morphology

Uniform fine particles of zinc oxide were prepared in three different morphologies and sizes by the controlled precipitation process from aqueous solutions of zinc nitrate in the presence of ethylene glycol. Ammonium hydroxide solution was used as the precipitant. Composition of the reactant solution, pH and temperature significantly affected the particle uniformity with respect to shape and size. Uniformity in the particles morphological feature was achieved under a narrow set of experimental conditions. pH of the reactant solutions and isoelectric point of zinc oxide were considered the master variables, controlling the particle size. One of the batch of the as-prepared zinc oxide particles was calcined at \(750{^{\circ }}\hbox {C}\), which increased its crystallinity, changed its various lattice parameters, Zn–O bond length and preferred orientation of the crystal hkl planes. Calcination had little effect on the original morphology of the zinc oxide particles.

Growth and characterization of ZnO nanostructure on TiO2-ZnO films as a light scattering layer for dye sensitized solar cells

In the present work, we studied the effect of light scattering layer on the performance of DSSCs. TiO2-ZnO thin films were coated onto FTO glass substrate by spin coating technique as a photoanode for DSSCs. ZnO nanorods with flower structures were potentiostatically grown on TiO2-ZnO films at various potentials from −1.1 to 1–1.3V as a light scattering layer. XRD patterns reveal that as the deposition potentials increase the growth of ZnO nanorods increases along with (101) plane orientation. FE-SEM images display agglomerated grains and nanorods with flower structures for TiO2-ZnO film, and ZnO has grown on TiO2-ZnO film at a deposition potential of −1.3V. UV–vis spectra confirm the TiO2-ZnO with ZnO nanorods having a higher light scattering effect, absorbance and dye loading than that of another film. The efficiency of the DSSCs consisting of without and with scattering layer is estimated to be 0.79 and 1.81%, respectively.

Highly c-Axis Oriented Growth and Optical Characterization of ZnO Pore-Like Structures Surrounded by Craters via Pulsed Laser Deposition

This research deals with the deposition and characterization of ZnO nanostructures by the pulsed laser deposition technique at various ambient pressures of oxygen on a silicon substrate at 600 ∘C temperature. X-ray diffraction study shows that the ZnO nanostructure is single crystal in nature and has strong c-axis orientation. The field emission scanning electron microscopic image shows that the formation of pores within the craters is highly sensitive to the oxygen pressure. The atomic force microscopy image reveals the reduction in surface roughness of the nanostructure indicating transformation of pores to particles. A near-band-edge emission peak along with the defect peaks arising from oxygen defects and zinc interstitials are observed in the photoluminescence spectra. The defect related emission due to O 2 vacancy decreases with increasing O 2 pressure due to more incorporation of O 2 during pulsed laser deposition.

Effects of the Duration of Ultrasonic Irradiation and the Atmospheric Environment on the Characteristics of ZnO Nanostructures via a Sonochemical Method

Effects of the Duration of Ultrasonic Irradiation and the Atmospheric Environment on the Characteristics of ZnO Nanostructures via a Sonochemical Method

Effects of the Duration of Ultrasonic Irradiation and the Atmospheric Environment on the Characteristics of ZnO Nanostructures via a Sonochemical Method

Effects of the Duration of Ultrasonic Irradiation and the Atmospheric Environment on the Characteristics of ZnO Nanostructures via a Sonochemical Method

A Novel Vible-Light Photodetector Based on Chlorophyll-Modified ZnO Nanoparticles

This paper reports a new material for visible-light detection based on chlorophyll-modified ZnO nanoparticles. ZnO nanoparticles were synthesized via a hydrothermal process. Chlorophyll was extracted from Katuk (Sauropus androgynus) leaves, an Indonesian vegetable which has many benefits for health. ZnO nanopartcles were mixed with the extracted chlorophyll, later to be formed into a film onto ITO coated glass substrate by the casting method. The hybrid chlorophyll-modified ZnO nanoparticle film was characterized for its optical absorption and current-voltage (I-V) property. A visible-light response of the hybrid chlorophyll-modified ZnO nanoparticle film can be seen on the I-V curves as well as a dynamic response. Full Text: PDF References D.J. Sornalatha, S. Bhuvaneswari, S. Murugesan, P. Murugakoothan, "Solochemical synthesis and characterization of ZnO nanostructures with different morphologies and their antibacterial activity", Optik 126, 63 (2015). CrossRef K.L. Foo, M. Kashif, U. Hashim, M.E. Ali, "Sol–gel derived ZnO nanoparticulate films for ultraviolet photodetector (UV) applications", Optik 124, 5373 (2013). CrossRef M. Procek, T. Pustelny, "A study of gas sensing properties of ZnO nanostructures activated by UV light", Phot. Lett. Poland 7, 50 (2015). CrossRef J. A. Anta, E. Guille?n, R. Tena-Zaera, "ZnO-Based Dye-Sensitized Solar Cells", J. Phys. Chem. C 116, 11413 (2012). CrossRef V. Sanna, N. Pala, V. Alzari, D. Nuvoli, M. Carcelli, "http://dx.doi.org/10.1016/j.matlet.2015.10.031", Mat. Lett. 162, 257 (2016). CrossRef C.O. Chey, X. Liu, H. Alnoor, O. Nur, M. Willander, "Fast piezoresistive sensor and UV photodetector based on Mn-doped ZnO nanorods", Phys. Status Solidi RRL 9(1), 87 (2015). CrossRef A. Kondapi, "Development of chlorophyll-protein complex nanoparticles for light harvesting and solar cell application", Int. J. Nanoparticles 7(3/4), 307 (2014). CrossRef S. Ashoka, G. Nagaraju, C.N. Tharamani, G.T. Chandrappa, "http://dx.doi.org/10.1016/j.matlet.2009.01.054", Mat. Lett. 63, 873 (2009). CrossRef J.B. Zvezdanovic, D.Z. Markovic, S.M. Milenkovic, "Zinc(II) and copper(II) complexes with pheophytin and mesoporphyrin and their stability to UV-B irradiation: Vis spectroscopy studies", J. Serb. Chem. Soc. 77(2), 187 (2012). CrossRef X. Lian, Y. Li, D. An, Y. Zou, Q. Wang, N. Zhang, "Synthesis of porous ZnO nanostructures using bamboo fibers as templates", Mat. Science-Poland 32(3), 514 (2014). CrossRef S. Wein, J. Zhao,W. Du, "Synthesis, characterization and acetone-sensing properties of bristlegrass-like ZnO nanostructure", Ceramics Internat. 41, 769 (2015). CrossRef

Screw-dislocation-driven growth of ZnO nanotubes seeded by self-perpetuating spirals during hydrothermal processing

We report the effects of precursor concentration on the characteristics of ZnO nanostructures during hydrothermal processing. Self-perpetuating surface spirals are fabricated at concentrations of 0.25 and 0.5 M, with samples grown at concentrations of 0.05 and 0.125 M exhibiting ZnO nanorods. This can be explained by a change in the growth mode from an initial columnar growth to a screw-dislocation-driven growth with decreased supersaturation. The screw dislocations nucleate at the V-shaped valleys of the columnar boundaries during the intermediate stage. We demonstrate that continuous screw-dislocation-driven growth leads to the formation of ZnO nanotubes having Burger’s vectors of 1.45 nm.

Synthesis and characterization of ZnO nanostructures on noble-metal coated substrates

In this work, ZnO nanostructures were fabricated on noble-metal (Au, Ag and Au–Ag alloys) coated silicon substrates by applying pulsed laser deposition. The samples were prepared at a substrate temperature of 550°C, an oxygen pressure of 5Pa, and a laser fluence of 2Jcm−2 – process parameters usually used for deposition of smooth and dense thin films. The metal layer's role is substantial for the preparation of nanostructures. Heating of the substrate changed the morphology of the metal layer and, subsequently, nanoparticles were formed. The use of different metal particles resulted in different morphologies and properties of the ZnO nanostructures synthesized. The morphology of the ZnO nanostructures was related to the Au–Ag alloy's content of the catalyst layer. It was found that the morphology of the ZnO nanostructures evolved from nanorods to nanobelts as the ratio of Au/Ag in the alloy catalyst was varied. The use of a small quantity of Ag in the Au–Ag catalyst (Au3Ag) layer resulted predominantly in the deposition of ZnO nanorods. A higher Ag content in the catalyst alloy (AuAg2) layer resulted in the growth of a dense structure of ZnO nanobelts.

Solochemical synthesis and characterization of ZnO nanostructures with different morphologies and their antibacterial activity

Zinc oxide nanostructures were synthesized by solochemical method using different precursors. ZnO nanostructures were characterized by X-ray diffraction, Scanning electron microscopy, Transmission electron microscopy and UV – vis diffuse reflectance/absorption spectroscopy. The X-ray diffraction patterns of different ZnO nanostructures suggest that the synthesized structures have hexagonal wurtzite structure of zinc oxide. Scanning electron microscopic and Transmission electron microscopic images revealed the different shapes and sizes of the zinc oxide nanostructures. The UV – vis absorption spectra of the zinc oxide nanostructures show blue-shift in wavelength corresponding to bulk. Band gap energies of zinc oxide nanostructures are determined by UV – vis diffuse reflectance spectra. The zinc oxide nanostructures were evaluated for their antibacterial activity against Gram-positive and Gram-negative bacteria. Gram-negative bacteria seemed to be more resistant to ZnO nanostructures than Gram-positive bacteria.

Synthesis and characterization of ZnO nanostructures using modified chemical bath deposition method

ZnO thin films were deposited using a simple, convenient and an inexpensive modified chemical bath method along with subsequent air annealing. The reaction mechanism for the growth of the ZnO nanostructure after the air annealing is also discussed. SEM observations reveal the formation of flowerlike nanostructures that are composed of leaf-like petals of thin nanosheets. The annealed ZnO nanostructures grow with the hexagonal crystal structure. The ZnO nanostructure exhibits a blue shift in its optical absorption spectrum. The room temperature photoluminescence study reveals UV emission peaks due to near band edge emissions along with defect related blue and green emission peaks.

Synthesis and characterization of ZnO nanostructures using palm olein as biotemplate.

BackgroundA green approach to synthesize nanomaterials using biotemplates has been subjected to intense research due to several advantages. Palm olein as a biotemplate offers the benefits of eco-friendliness, low-cost and scale-up for large scale production. Therefore, the effect of palm olein on morphology and surface properties of ZnO nanostructures were investigated.ResultsThe results indicate that palm olein as a biotemplate can be used to modify the shape and size of ZnO particles synthesized by hydrothermal method. Different morphology including flake-, flower- and three dimensional star-like structures were obtained. FTIR study indicated the reaction between carboxyl group of palm olein and zinc species had taken place. Specific surface area enhanced while no considerable change were observed in optical properties.ConclusionPhase-pure ZnO particles were successfully synthesized using palm olein as soft biotemplating agent by hydrothermal method. The physico-chemical properties of the resulting ZnO particles can be tuned using the ratio of palm olein to Zn cation.

Microwave hydrothermal synthesis and characterization of ZnO nanostructures in aqueous solution

ZnO nanostructures were prepared in aqueous solution by microwave hydrothermal synthesis. Xray diffraction (XRD) and field emission scanning electron microscopy (FESEM) were used to characterize ZnO nanostructures (ZNs). The effects of pH, reaction temperature and reaction time on yield of ZnO were investigated. The yield of ZnO increased significantly with the increase of pH value, reaction temperature and reaction time. High yield and well crystallinity of ZNs could be obtained at 120°C for 60min by microwave hydrothermal synthesis. The spherical and rugby-like ZNs were obtained at 120°C without triethanolamine (TEA) and with TEA (mass ratio, \(r = m_{Zn^{2 + } }\): mTEA = 1: 1), respectively. The concentration of Zn(OH)4−2 ions in the reaction solution and TEA had an important effect on the nucleation and morphology of ZnO nanostructures. Mechanism for the formation of ZnO nanostructures was proposed.

Synthesis and Characterization of ZnO Nanostructures by Polymeric Precursor Route

Zinc oxide nanoand submicrostructures have been synthesized controllably by polymeric precursor method (Pechini). In this approach, zinc acetate Zn(CH3COO−)2·2H2O, citric acid and ethylene glycol were used as the source of Zn2+, the chelating agent and the connecting agent, respectively. The microstructure of the ZnO nanoand submicrostructures was characterized by X-ray diffractometry and scanning electron microscopy and the optical property was investigated by the room temperature photoluminescence spectra. The effect of ethylene glycol to citric acid mole ratio on the morphology and structure of the products was discussed.

Changing the Shape of ZnO Nanostructures by Controlling Oxygen Concentration: From Tetrapod-Like to Dandelion-Like Nanostructures

The tetrapod-like and two different kinds of dandelion-like structures had been controlledly synthesized on c-plane sapphire substrates by a simple chemical vapor deposition method. In the growing process, a semi-sealed quartz tube was utilized to create spatial variation of oxygen concentration. X-ray diffraction and scanning electron microscopy were employed to analyze crystal structures and morphologic characteristics of ZnO nanostructures synthesized in different regions. It is suggested that oxygen concentration is the critical experimental parameter for controlling and modifying the morphology during the nucleation and growth, which will lead to different nanostructures.

Synthesis and Characterization of ZnO Nanostructures with Macroscopic Gel-Like Morphology

Extended abstract of a paper presented at Microscopy and Microanalysis 2010 in Portland, Oregon, USA, August 1 – August 5, 2010.

Synthesis of Tetrapodlike Zinc Oxide Nanostructures by Inductive Heating

The inductive heating method is used to synthesize regular tetrapodlike zinc oxide nanostructures on a glass substrate. The morphology of tetrapodlike ZnO nanostructures is investigated by scanning electron microscopy. It is found that the tetrapodlike ZnO structure fabricated by inductive heating is smaller than that fabricated by PVD. Therefore, more emission sites can be generated with the tetrapodlike ZnO structures obtained by inductive heating. The field-emission characteristics of ZnO nanostructures are also measured in this letter. The measurement results show that the tetrapodlike ZnO nanostructures obtained by the inductive heating method have low turn-on electric field and high emission current. Its field-emission performance is better than that of the tetrapod ZnO emitters obtained by PVD due to its good morphology and adhesion on substrate. Because ZnO nanostructures can grow directly on a glass substrate with the inductive heating method, it is very useful for the application in the field-emission display panel.

Characterization of ZnO nanostructures: A challenge to positron annihilation spectroscopy and other methods

AbstractZnO nanostructures are of special interest for device applications. However, their structural characterization remains an ongoing challenge. This paper reviews recent efforts and latest achievements in this direction. Results comprise PAS in the form of Slow Positron Implantation Spectroscopy (SPIS) and Pulsed Low Energy Positron Lifetime Spectroscopy (PLEPS), Nuclear Reaction Analysis (NRA), Atomic Force Microscopy (AFM), conductive AFM (C‐AFM), Nuclear Magnetic Resonance (NMR), Electron Spin Resonance (ESR), Photoluminescence (PL) spectroscopy, and latest theoretical investigations of structure‐related and positron properties of selected defects. The fundamental importance of a relationship between fabrication conditions, native defect formation, and resulting optical and electronic properties is demonstrated by getting either inferior (nanorods) or significantly improved (tetrapods) optical properties compared to single crystal samples, depending on the nanostructure fabrication method. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

Growth Mechanism and Characteristics of ZnO Nanostructures with In and Ga Dopings

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