Properties Of Zinc Oxide Nanostructures Research Articles

Influence of (Co+Al) co−doping on structural, micro-structural, optical and electrical properties of nanostructured zinc oxide

This study investigates the effect of (Co + Al) co−doping on the physical properties of the ZnO nanoparticles, synthesized via the simple co−precipitation method. X−ray diffraction (XRD) analysis revealed a hexagonal structure for all samples, with a formation of Al2O3 phase in both Zn0.98Co0.01Al0.01O and Zn0.94Co0.01Al0.05O nanoparticles. The crystallite size increased from 26.5 nm for ZnO to 16.6 nm for Zn0.94Co0.01Al0.05O nanoparticles. Scanning electron microscopy (SEM) technique showed a notable alteration in the morphology of ZnO upon the incorporation of Al. A transition from spherical nanoparticles in ZnO and Co doped ZnO to irregular, dendritic-like structures in (Co + Al) co−doped nanoparticles is observed. Transmission electron microscopy (TEM) substantiated the presence of the Al2O3 phase in the co−doped samples. Raman and FTIR spectroscopy confirmed the incorporation of Co and Al into the ZnO lattice through the presence of Co–O–Co and Al–O bonds. Optical characterization indicated a decrease in the band gap energy from 3.18 eV in ZnO to 2.84 eV in Zn0.94Co0.01Al0.05O nanoparticles. Electrical conductivity measurements revealed an increase from 1.2 × 10−4 Ω−1 cm−1 to 1.8 × 10−3 Ω−1 cm−1 as the Al content increased from 0 % to 5 % at the frequency of 103 Hz and the temperature of 423K. Likewise, dielectric constant raised from 775 in ZnO to 5455 in Zn0.94Co0.01Al0.05O nanoparticles at the temperature 423K. These results highlight the potential of (Co + Al) co−doped ZnO nanoparticles for advanced optoelectronic applications.

Effect of annealing temperature on the morphological, structural, and optical properties of zinc oxide nanostructures prepared by the sol–gel spin coating technique

ABSTRACT This study investigates the impact of different annealing temperatures on the properties of zinc oxide (ZnO) films, particularly at lower temperatures (150-550°C). The films were synthesized using the sol-gel technique, with zinc acetate dihydrate (ZAD) as the precursor and ethanolamine (MEA) as the stabilizing agent. Surface morphology, structural, and optical properties of the films were examined using various techniques. X-ray diffraction confirmed the (002) wurtzite crystal structure, while crystallite size, strain, stress, energy density model, and dislocation density are estimated using three models of Williamson-Hall (W-H) approach.Raman data indicated the hexagonal wurtzite structure of the film. Optical analysis showed good transmittance, with a bandgap estimated between 3.32 and 3.56 eV for all samples. SEM image analysis revealed a nanowall structure in the ZnO thin film annealed at 150°C. However, increasing the annealing temperature led to a more pronounced wrinkled morphology.

Nickel oxide doping impact on the NO2 sensing properties of nanostructured zinc oxide deposited by spray pyrolysis

In this study, zinc oxide was doped with varying Nickel oxide nanostructured thin film concentrations using spray pyrolysis at 400 °C. At low Ni content, the ZnO phase exhibited polycrystalline structures, whereas a high Ni concentration resulted in the development of an additional NiO phase. The morphological analysis indicates the presence of nano-spherical structures at lower Ni concentrations, with nanoflakes embedded at varying orientations. The density of the nanoflakes structure was observed to increase as the Ni content was increased, enhancing the surface-to-volume ratio, which has potential applications in gas sensing. The highest sensitivity was detected for the sample doped with the highest Ni content, which can be attributed to its superior effective surface area. The optimal sensitivity was 45.26% at 200 °C.

Prediction of electronic structure and nonlinear optical properties of zinc oxide nanostructures by experimental characterization and theoretical investigation

Prediction of electronic structure and nonlinear optical properties of zinc oxide nanostructures by experimental characterization and theoretical investigation

A High-Performance Antibacterial Nanostructured ZnO Microfluidic Device for Controlled Bacterial Lysis and DNA Release.

In this work, the antibacterial properties of nanostructured zinc oxide (ZnO) surfaces are explored by incorporating them as walls in a simple-to-fabricate microchannel device. Bacterial cell lysis is demonstrated and quantified in such a device, which functions due to the action of its nanostructured ZnO surfaces in contact with the working fluid. To shed light on the mechanism responsible for lysis, E. coli bacteria were incubated in zinc and nanostructured ZnO substrates, as well as the here-investigated ZnO-based microfluidic devices. The unprecedented killing efficiency of E. coli in nanostructured ZnO microchannels, effective after a 15 min incubation, paves the way for the implementation of such microfluidic chips in the disinfection of bacteria-containing solutions. In addition, the DNA release was confirmed by off-chip PCR and UV absorption measurements. The results indicate that the present nanostructured ZnO-based microfluidic chip can, under light, achieve partial inactivation of the released bacterial DNA via reactive oxygen species-mediated oxidative damage. The present device concept can find broader applications in cases where the presence of DNA in a sample is not desirable. Furthermore, the present microchannel device enables, in the dark, efficient release of bacterial DNA for downstream genomic DNA analysis. The demonstrated potential of this antibacterial device for tailored dual functionality in light/dark conditions is the main novel contribution of the present work.

A review on biological synthesis of ZnO nanostructures and its application in photocatalysis mediated dye degradation: An overview.

Zinc oxide (ZnO) has several industrial applications due to its versatile properties, which lead to its continuously increasing demand in different industrial sectors. Additionally, ZnO nanostructures possess unique photocatalytic activity, and because of this, they are being applied to degrade organic dyes through photocatalysis for wastewater treatment. Nevertheless, chemical synthesis methods to develop ZnO nanostructures have raised concerns related to environmental issues, furthermore, these methods are found to be costly and tedious. As a result, the synthesis of ZnO nanostructures using green methods is gaining popularity due to its low cost and eco-friendly mode, while avoiding the use of toxic chemicals. Green synthesis of ZnO nanostructures using different biological approaches involving plants, algae, and different microorganism-derived bioactive compounds has been well reported for diverse applications. Among different applications, ZnO nanostructures that enable photocatalysis to degrade dye have been found to be imperative for wastewater treatments. Therefore, the current review explores recent studies on green synthesis approaches to prepare ZnO nanostructures via adopting different biological methods that rely on plants, algae, and bacterial microorganisms. The properties of ZnO nanostructures, along with their green synthesis routes and feasible mechanisms, have also been discussed in this review. This review focuses on the use and efficiency of green route synthesized ZnO nanostructures as nanophotocatalysts for the degradation of organic dyes in wastewater treatment. Additionally, existing challenges in green synthesis methods and the efficiency of ZnO nanostructures to degrade organic dyes following photocatalysis has been discussed.

A comparative study of antibacterial, anticancer and gas-sensing properties of zinc oxide nanostructures synthesized by different routes

A comparative study of antibacterial, anticancer and gas-sensing properties of zinc oxide nanostructures synthesized by different routes

Tailoring the Structural, Optical and Electrical Properties of Zinc Oxide Nanostructures by Zirconium Doping

Owing to its low resistivity, high transmittance, and tunable optical band gap, ZnO is of great interest for optoelectronic applications. Herein, the sol–gel technique was used to synthesize un-doped and zirconium-doped zinc oxide (ZZO) nanostructures with different concentrations of Zirconium (Zr). X-ray diffraction (XRD), scanning electron microscope (SEM), Raman spectroscopy, Fourier transform infrared spectroscopy (FTIR), UV-Vis spectroscopy, and photoluminescence (PL) measurements were used to investigate the influence of Zr doping on the structural, optical, and electrical properties of developed nanostructures. XRD and SEM confirmed the increase in crystallite size with increasing concentrations of Zr. Raman analysis indicated the presence of oxygen vacancies in synthesized nanostructures. UV-Vis spectroscopy illustrated the blue shift of band gap and red shift of the absorption edge for ZZO nanostructures with increasing concentrations of Zr. For the measurement of electrical properties, the spin-coating technique was used to deposit un-doped and Zr-doped ZnO layers of ~165 nm thickness. The four-probe-point (4PP) method illustrated that the doping of Zr caused a reduction in electrical resistance. Hall Effect measurements showed a high value, 3.78 × 1020 cm−3, of the carrier concentration and a low value, 10.2 cm2/Vs, of the carrier mobility for the Zr-doped layer. The high optical transmittance of ~80%, wide band gap of 3.51 eV, low electrical resistivity of 1.35 × 10−3 Ω·cm, and maximum carrier concentration of 3.78 × 1020 cm−3 make ZZO nanostructures one of the most promising candidates for the application of transparent conductive oxide (TCO) in optoelectronic devices.

Investigation and Correlation of Morphological, Structural and Spectroscopic Properties of Zinc Oxide Nanostructures Synthesized by Ball-Milling

Investigation and Correlation of Morphological, Structural and Spectroscopic Properties of Zinc Oxide Nanostructures Synthesized by Ball-Milling

UV induced photocatalytic and antibacterial studies of zinc oxide nanoflowers prepared via casein assisted low-temperature method

We report the photocatalytic and antimicrobial properties of zinc oxide nanostructures synthesized using a low-temperature, facile method with the assistance of milk protein, casein. The nanoflower structure with hexagonal-shaped petals was identified in casein assisted zinc oxide, whereas the flower embryo was obtained without casein. The influence of casein in growth mechanism, morphology, and biofunctionalization is also discussed. A noticeable change was observed in the fluorescence spectra of casein added sample. BET analysis reveal that the addition of casein increases the surface area by 60% which implies casein acts as a capping agent during the preparation. In the presence of casein, the larger surface area of the nanostructure provides a greater number of active sites for interaction, allowing for increased photocatalytic activity. The improved antibacterial activity implies the increased diffusing capacity of casein-added zinc oxide through the cell membrane.

Effects of Morphological and Structural Properties of Zinc Oxide Nanostructures on the Performance of an Ultraviolet Detector

This study proposed cost-effective metal-oxide photoconductors using a glass substrate; three different ZnO nanostructures were used as sensing materials. ZnO-sensing materials were fabricated in thin films and one-dimensional nanorods (NRs). ZnO thin films were fabricated using the ultrasonic spray pyrolysis method, while ZnO nanorods were fabricated by employing the hydrothermal technique. The results reveal that ZnO thin film-sensing materials exhibit higher performance than nanorods. The results also show that ZnO thin films have the highest performance (responsivity: 8884 A/W; detectivity: 6.7 x 1012 Jones; sensitivity: 403%; rise time: 12 s; recovery time: 34 s). The better performance of the ZnO thin films’ UV detector to the higher ratio of photocurrent to dark current. ZnO NRs-based devices have a higher dark current, possibly because of the large number of crystal defects found in ZnO NRs, as indicated by defective emissions in the photoluminescence spectra.

Исследование свойств наноструктур оксида цинка, полученных методом импульсного электрохимического осаждения

The properties of zinc oxide nanostructures allow it to be used in various fields of science and technology. The increased interest in this compound is caused by a rare combination of optical and electrophysical properties. The films of this compound have good piezoelectric and electroluminescent properties, due to which zinc oxide can be used as functional layers in surface acoustic waves, elements of nonlinear optics. This allows the oxide to pass visible radiation. In this paper, we study the influence of the conditions for obtaining a coating by pulsed electrochemical deposition on the forbidden zones and the power of a coating based on zinc oxide. It was shown that the temperature and duty cycle of pulses are of great importance in the formation of the coating, which is explained by the kinetics of the electrochemical reaction. The Urbach energy increases with a decrease in crystalline size and increased by almost 3 times, compared with a coarse-grained sample.

Morphology-dependent structural and optical properties of ZnO nanostructures

Zinc oxide nanostructures with three different morphologies, namely, nanoparticles (NP), nanorods (NR) and nanosheets (NS) were synthesized using chemical co-precipitation method. X-ray diffraction patterns showed that all the ZnO nanostructures had hexagonal wurtzite structures. The average crystallite size of NP, NS, and NR was found to be 25, 27 and 35 nm, respectively. The morphology and size of nanostructures were confirmed by scanning electron microscopy and transmission electron microscopy. The optical properties of zinc oxide nanostructures were investigated using UV–Vis absorption spectroscopy and photoluminescence (PL) spectroscopy. The optical band gap was found to be 3.26, 3.24 and 3.10 eV for NP, NS, and NR nanostructures, respectively. It was clearly observed from the PL spectrums that luminescence intensity was maximum for NP in the UV region and maximum for NS in the visible region. It is evident from the results that by changing the size and morphology of ZnO nanostructures, the optical properties can be tuned according to their desired applications.

Effect of post annealing treatment on electrical and structural properties of zinc oxide nanostructures

This paper work presents the effect of post annealing treatment on electrical and structural properties of nanostructured Zinc Oxide (ZnO) which was fabricated by hydrothermal process. I-V measurement shown the nanostructured ZnO exhibit Schottky conductive mechanism. The resistance of nanostructured ZnO was reduced as respected to the annealing temperature. XRD and EDX analysis confirmed the presence of ZnO element of Si substrate. Finally, FESEM analysis indicated a small nanoparticle growth on Si surface have 28.64 nm of average diameter size. These experiment results revealed, annealing treatment might be used to assist the formation of nanostructured ZnO on bare substrate.

Photoluminescence quenching, structures, and photovoltaic properties of ZnO nanostructures decorated plasma grown single walled carbon nanotubes

Zinc oxide (ZnO) nanostructures were successfully grown directly on single walled carbon nanotubes (SWCNT) template through the CO2 laser-induced chemical liquid deposition (LCLD) process. Photoluminescence (PL) of the deposited ZnO/SWCNT hybrid composites exhibits, at room temperature, a narrow near UV band located at 390 nm with no emission bands in the visible region, indicating a high degree of crystalline quality of the ZnO nanostructures. Moreover, when the relative SWCNT loads are varied within the composites, the PL intensity and the diffused optical reflectance diminish in comparison with those of ZnO alone, owing to the transfer of photo-excited electrons from ZnO to the SWCNT, and the enhancement of the optical absorbance, respectively. Finally, these ZnO/SWCNT hybrid composites are integrated into a heterojunction photovoltaic-based device, using PEDOT:PSS on ITO/glass substrate. The devices show an evident p–n junction behavior in the dark, and a clear I–V curve shift downward when illuminated with an open-circuit voltage of 1.1 V, a short circuit current density of 14.05 μA cm−2, and a fill factor of ∼35%. These results indicate that these composites fabricated via LCLD process could be promising for optoelectronic and energy-harvesting devices.

Temperature effect on morphology and electrochemical properties of nanostructured ZnO as anode for lithium ion batteries

Nanostructured zinc oxide (ZnO) with different morphology has been synthesised by a facile hydrothermal method combining calcination procedure at different temperatures. The effect of calcination temperature on the morphology and electrochemical properties of as-synthesised ZnO is investigated. X-ray diffraction, scanning electron microscopy and transmission electron microscopy were applied to characterise the phase composition and microstructure of the synthesised samples. The electrochemical tests of as-synthesised ZnO as an anode material for lithium ion batteries (LIBs) reveal that ZnO nanoparticles prepared at 700°C deliver the largest capacity of 1815.8 mAh g−1, while cabbage-like ZnO nanosheets prepared at lower temperatures display better cycling stability. It is believed that the diverse morphologies of nanostructured ZnO crucially affect their electrochemical properties as an anode material for LIBs.

Effects of Ag doping amount on structural properties of zinc oxide nanostructures

We investigated the structural properties of zinc oxide (ZnO) nanostructures grown on the glass substrates using the chemical solution deposition while being doped with Ag in different amounts. The undoped ZnO nanostructures were composed of flower-like bundles consisting of nanorods with a length of ~2.3μm and hexagonal disks with a diameter of ~2.2μm and thickness of ~350nm. In these flower-like bundles, the diameter and density of the nanorods at the center were smaller and higher, respectively, than those of the nanorods at the edge. With addition of Ag in the ZnO, the Ag nanoparticles were formed on the substrate, which led to suppress the growth of the flower-like bundles and decrease the thickness of the disks. The intensities of the diffraction peaks corresponding to the ZnO and Ag phases decreased and increased, respectively, with an increase in the amount of Ag added. It was found that the Ag-doped ZnO nanostructures contained Ag particles, which formed a continuous thin film, resulting in low sheet resistance (~1Ω/sq).

Effect of nitrate concentration on the electrochemical growth and properties of ZnO nanostructures

Zinc oxide (ZnO) nanostructures were deposited under potentiostatic control on indium tin oxide coated glass substrate from an aqueous solution containing zinc nitrates. Voltammograms were recorded to determine the optimal potential region for the deposition of ZnO. The deposition was carried out at various concentrations of Zn+2 and constant bath temperature (65 °C). The nucleation and growth kinetics at the initial stages of ZnO studied by current transients indicated a 3D island growth (Volmer–Weber). It is characterized by an instantaneous nucleation mechanism followed by diffusion-limited growth. The Mott–Schottky measurements, the flat band potential and the donor density for the ZnO nanostructures were determined. The morphological, structural, and optical properties of the nanostructures have been investigated. Scanning electron microscopy images showed different sizes and morphologies of the nanostructures which depends on the concentrations of Zn+2. X-ray diffraction study confirms the wurtzite phase of the ZnO nanostructures with high crystallinity. UV–visible spectra showed a significant optical transmission (up to 90 %), which decreased with Zn2+ concentrations. The energy band gap values have been estimated to be in the range 3.36–3.54 eV.

Effect of Metal Catalyst Morphology on the Growth of Zinc Oxide Nanostructure by Thermal Vapor Deposition Method

This paper reports on the effects of gold (Au) catalyst on the growth of zinc oxide (ZnO) nanostructures by thermal chemical vapor deposition (TCVD). The thickness of Au catalyst was varied from 5 to 15 nm. The Au catalyst was annealed at 500 °C prior to the deposition of ZnO nanostructures by thermal chemical vapor deposition (TCVD). The morphology of the Au catalyst at different thickness and also ZnO nanostructures were characterized by field emission scanning electron microscopy (FESEM). The material component and crystalline properties of ZnO nanostructures were determined using Energy Dispersive X-ray spectroscopy (EDX) and also Raman Spectroscopy respectively. We found that the shape of the deposited ZnO nanostructures were different on different thickness of Au catalyst. There was no growth of ZnO on the 5 nm thick Au observed by FESEM and supported by EDX due to very small amount of Zn. On the 10 and 15 nm thick Au, growth of ZnO nanostructures were clearly observed.

Heavy element doping for enhancing thermoelectric properties of nanostructured zinc oxide

ZnO is a high melting point, high charge carrier mobility semiconductor with potential as a thermoelectric material, but its high thermal conductivity κ is the limiting factor for increasing the thermoelectric figure of merit ZT. Here, we demonstrate that doping ZnO with heavy elements can significantly enhance ZT. Indium doping leads to ultralow κ ∼ 3 W m−1 K−1 and a high power factor α2σ ∼ 1.230 × 10−3 W m−1 K−2, yielding ZT1000K ∼ 0.45 that is ∼80% higher than non-nanostructured In–Zn–O alloys. Although Bi doping also yields a high Seebeck coefficient of α300K ∼ 500 μV K−1, Bi segregation, grain growth and defect complexing are unfavorable for increasing ZT. Thus, besides increased impurity scattering of phonons, the concurrence of nanostructuring and charge carrier concentration control is key to ZT enhancement. Our results open up a new means to realize high ZT thermoelectric nanomaterials based on ZnO.