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Sample records for zno nanostructures synthesized

  1. Photoluminescence of Sequential Infiltration Synthesized ZnO nanostructures

    NASA Astrophysics Data System (ADS)

    Ocola, Leonidas; Gosztola, David; Yanguas-Gil, Angel; Connolly, Aine

    We have investigated a variation of atomic layer deposition (ALD), called sequential infiltration synthesis (SiS), as an alternate method to incorporate ZnO and other oxides inside polymethylmethacrylate (PMMA) and other polymers. Energy dispersive spectroscopy (EDS) results show that we synthesize ZnO up to 300 nm inside a PMMA film. Photoluminescence data on a PMMA film shows that we achieve a factor of 400X increase in photoluminescence (PL) intensity when comparing a blank Si sample and a 270 nm thick PMMA film, where both were treated with the same 12 alternating cycles of H2O and diethyl zinc (DEZ). PMMA is a well-known ebeam resist. We can expose and develop patterns useful for photonics or sensing applications first, and then convert them afterwards into a hybrid polymer-oxide material. We show that patterning does indeed affect the photoluminescence signature of native ZnO. We demonstrate we can track the growth of the ZnO inside the PMMA polymer using both photoluminescence and Raman spectroscopy and determine the point in the process where ZnO is first photoluminescent and also at which point ZnO first exhibits long range order in the polymer. This work was supported by the Department of Energy under Contract No. DE-AC02-06CH11357. Use of the Center for Nanoscale Materials was supported by the U. S. Department of Energy, Office of Basic Energy Sciences, under Contract No. DE-AC02-06CH11357.

  2. Characteristics of ZnO nanostructures synthesized by sonochemical reaction: Effects of continuous and pulse waves

    SciTech Connect

    Widiyastuti, W., E-mail: widi@chem-eng.its.ac.id; Machmudah, Siti; Kusdianto,

    Nanostructured ZnO was synthesized by a sonochemical reaction. Ultrasonic irradiation were set up in continuous, pulse in 3 seconds on and a second off (on:off=3:1), and pulse in 2 seconds on and a second off (on:off=2:1) wave modes for 1.5 hours. The characteristics of particles generated by these modes such as morphology, crystallinity, FTIR, photoluminescence, and photocatalytic activity to degrade methylene blue were compared. Zinc nitrate and ammonia water-based solutions were selected as chemicals without the addition of other surfactants. The morphology of the generated ZnO particles could be tuned from flower-like, needle- or hairy-like, and spherical structures by changingmore » the mode of ultrasonic irradiation from continuous, on:off=3:1, and on:off=2:1 modes, respectively. The generated particles indicated that a wurtzite structure of ZnO in a hexagonal phase was formed. The crystalline sizes of particles generated in continuous, on:off=3:1, and on:off=2:1 modes were 28, 27, 24 nm. A similar position of reduction peak of FTIR in all samples indicated that no differences in particles chemical bonding characteristics. Photoluminescence intensity was also decreased with changes the wave mode from continuous to pulse. Photocatalytic activity was also evaluated resulting in particles synthesized by continuous mode had the highest methylene blue degradation degree following by on:off=3:1, and on:off=2:1 modes.« less

  3. Characteristics of ZnO nanostructures synthesized by sonochemical reaction: Effects of continuous and pulse waves

    NASA Astrophysics Data System (ADS)

    Widiyastuti, W.; Machmudah, Siti; Kusdianto, Nurtono, Tantular; Winardi, Sugeng

    2015-12-01

    Nanostructured ZnO was synthesized by a sonochemical reaction. Ultrasonic irradiation were set up in continuous, pulse in 3 seconds on and a second off (on:off=3:1), and pulse in 2 seconds on and a second off (on:off=2:1) wave modes for 1.5 hours. The characteristics of particles generated by these modes such as morphology, crystallinity, FTIR, photoluminescence, and photocatalytic activity to degrade methylene blue were compared. Zinc nitrate and ammonia water-based solutions were selected as chemicals without the addition of other surfactants. The morphology of the generated ZnO particles could be tuned from flower-like, needle- or hairy-like, and spherical structures by changing the mode of ultrasonic irradiation from continuous, on:off=3:1, and on:off=2:1 modes, respectively. The generated particles indicated that a wurtzite structure of ZnO in a hexagonal phase was formed. The crystalline sizes of particles generated in continuous, on:off=3:1, and on:off=2:1 modes were 28, 27, 24 nm. A similar position of reduction peak of FTIR in all samples indicated that no differences in particles chemical bonding characteristics. Photoluminescence intensity was also decreased with changes the wave mode from continuous to pulse. Photocatalytic activity was also evaluated resulting in particles synthesized by continuous mode had the highest methylene blue degradation degree following by on:off=3:1, and on:off=2:1 modes.

  4. Structural, optical, and improved field-emission properties of tetrapod-shaped Sn-doped ZnO nanostructures synthesized via thermal evaporation.

    PubMed

    Zhou, Xiongtu; Lin, Tihang; Liu, Yuhui; Wu, Chaoxing; Zeng, Xiangyao; Jiang, Dong; Zhang, Yong-ai; Guo, Tailiang

    2013-10-23

    High-quality tetrapod-shaped Sn-doped ZnO (T-SZO) nanostructures have been successfully synthesized via the thermal evaporation of mixed Zn and Sn powder. The effects of the Sn dopant on the morphology, microstructure, optical, and field-emission (FE) properties of T-SZO were investigated. It was found that the growth direction of the legs of T-SZO is parallel to the [0001] crystal c-axis direction and that the incorporation of Sn in the ZnO matrix increases the aspect ratio of the tetrapods, leads to blue shift in the UV region, and considerably improves the FE performance. The results also show that tetrapod cathodes with around a 0.84 atom % Sn dosage have the best FE properties, with a turn-on field of 1.95 V/μm, a current density of 950 μA/cm2 at a field of 4.5 V/μm, and a field-enhancement factor as high as 9556.

  5. One-dimensional ZnO nanostructures.

    PubMed

    Jayadevan, K P; Tseng, T Y

    2012-06-01

    The wide-gap semiconductor ZnO with nanostructures such as nanoparticle, nanorod, nanowire, nanobelt, nanotube has high potential for a variety of applications. This article reviews the fundamentals of one-dimensional ZnO nanostructures, including processing, structure, property, application and their processing-microstructure-property correlation. Various fabrication methods of the ZnO nanostructures including vapor-liquid-solid process, vapor-solid growth, solution growth, solvothermal growth, template-assisted growth and self-assembly are introduced. The characterization and properties of the ZnO nanostructures are described. The possible applications of these nanostructures are also discussed.

  6. Hydrothermal temperature effect on crystal structures, optical properties and electrical conductivity of ZnO nanostructures

    NASA Astrophysics Data System (ADS)

    Dhafina, Wan Almaz; Salleh, Hasiah; Daud, Mohd Zalani; Ghazali, Mohd Sabri Mohd; Ghazali, Salmah Mohd

    2017-09-01

    ZnO is an wide direct band gap semiconductor and possess rich family of nanostructures which turned to be a key role in the nanotechnology field of applications. Hydrothermal method was proven to be simple, robust and low cost among the reported methods to synthesize ZnO nanostructures. In this work, the properties of ZnO nanostructures were altered by varying temperatures of hydrothermal process. The changes in term of morphological, crystal structures, optical properties and electrical conductivity were investigated. A drastic change of ZnO nanostructures morphology and decreases of 002 diffraction peak were observed as the hydrothermal temperature increased. The band gap of samples decreased as the size of ZnO nanostructure increased, whereas the electrical conductivity had no influence on the band gap value but more on the morphology of ZnO nanostructures instead.

  7. The growth of ZnO nanostructures using Arginine

    NASA Astrophysics Data System (ADS)

    Singh, Baljinder; Moudgil, Lovika; Singh, Gurinder; Kaura, Aman

    2018-05-01

    The growth mechanism of Zinc oxide (ZnO) nanomaterial with amino acid (Arginine) is explained at different shapes. The present study of ZnO nanostructures (NSs) in the presence of Arginine has enabled us to not only determine the growth mechanism of ZnO NSs but also to determine the effect of Arginine at different temperature of reactants. The synthesized samples are characterized using transmission electron microscopy (TEM) and X-ray diffraction (XRD). Results reveal that Arginine is responsible for formation of NSs. Based on these results, a plausible mechanism is explained.

  8. Influence of the morphology of ZnO nanostructures on luminescent and photovoltaic properties

    NASA Astrophysics Data System (ADS)

    Ibrayev, N. Kh.; Ilyassov, B. R.; Afanasyev, D. A.

    2017-03-01

    Arrays of ZnO nanorods and nanoplates are synthesized by the hydrothermal and electrochemical methods, respectively. The photoluminescence spectra indicate that the nanoplates have a more defective structure than the nanorods. The obtained ZnO nanostructures are used as the basis to construct dye-sensitized solar cells. The influence of morphology and defectiveness of ZnO nanostructures on the luminescent and photovoltaic properties of the cells is studied.

  9. Confocal Raman microscopy of one dimensional ZnO nanostructures

    NASA Astrophysics Data System (ADS)

    Singamaneni, Srikanth; Gupta, Maneesh; Yang, Rusen; Wang, Zhong; Tsukruk, Vladimir

    2009-03-01

    ZnO nanostructures with various shapes (vertically aligned nanorods, nanobelts, nanohelixes, nanorings) have been synthesized using both vapor phase and solution growth methods. In the simplest example of a nanobelt, the fast growth direction can be either (21 1 0) or (011 0) or (0001). Here, we show that confocal Raman microscopy can be employed as a fast and nondestructive analytical technique to identify the crystal planes and reveal the relative orientation of the ZnO nanostructure. Various features of the Raman spectrum of ZnO nanostructures (presence of the A1(TO) mode, width of the E2 mode) were found to be sensitive to relative orientation of the incident source laser and the crystal plane. Furthermore, owing to the optical anisotropy of ZnO, Raman scattering from the substrate is modulated (either enhanced or suppressed with respect to the background) depending on the polarization of the incident light with respect to orientation of the nanobelt. The results presented here describe a novel method to nondestructively identify the growth, relative orientation, and the waveguiding properties of the ZnO nanostructures.

  10. Complex and oriented ZnO nanostructures.

    PubMed

    Tian, Zhengrong R; Voigt, James A; Liu, Jun; McKenzie, Bonnie; McDermott, Matthew J; Rodriguez, Mark A; Konishi, Hiromi; Xu, Huifang

    2003-12-01

    Extended and oriented nanostructures are desirable for many applications, but direct fabrication of complex nanostructures with controlled crystalline morphology, orientation and surface architectures remains a significant challenge. Here we report a low-temperature, environmentally benign, solution-based approach for the preparation of complex and oriented ZnO nanostructures, and the systematic modification of their crystal morphology. Using controlled seeded growth and citrate anions that selectively adsorb on ZnO basal planes as the structure-directing agent, we prepared large arrays of oriented ZnO nanorods with controlled aspect ratios, complex film morphologies made of oriented nanocolumns and nanoplates (remarkably similar to biomineral structures in red abalone shells) and complex bilayers showing in situ column-to-rod morphological transitions. The advantages of some of these ZnO structures for photocatalytic decompositions of volatile organic compounds were demonstrated. The novel ZnO nanostructures are expected to have great potential for sensing, catalysis, optical emission, piezoelectric transduction, and actuations.

  11. Effect of Eu3+ doping on the structural, morphological and luminescence properties ZnO nanostructures

    NASA Astrophysics Data System (ADS)

    Vinoditha, U.; Balakrishna, K. M.; Sarojini, B. K.; Narayana, B.; Kumara, K.

    2018-05-01

    Pure and Eu3+ ions (1, 3, 5 atomic wt%) doped ZnO nanostructures are synthesized by a surfactant assisted hydrothermal method. The effect of doping concentrations on structural, morphological and optical properties of ZnO nanostructures is studied. The XRD analysis shows good crystallinity and the phase purity of the ZnO nanostructures. A shift in the standard Zn-O stretching mode after Eu3+ doping is observed in the FTIR spectra. The images of FESEM demonstrate the morphological variations from hexagonal nanorods to nanoflowers on varying the dopant concentrations. Substitution of Eu3+ ions into Zn2+ sites is confirmed by EDX analysis. The dominance of particle shape over the UV-Visible absorption properties of the prepared samples is noticed. The photoluminescence (PL) emission of undoped and doped ZnO nanostructures show dominant near band edge emission (NBE) in the UV region and minor defect induced deep level emissions in the visible region.

  12. Doping effect on SILAR synthesized crystalline nanostructured Cu-doped ZnO thin films grown on indium tin oxide (ITO) coated glass substrates and its characterization

    NASA Astrophysics Data System (ADS)

    Dhaygude, H. D.; Shinde, S. K.; Velhal, Ninad B.; Takale, M. V.; Fulari, V. J.

    2016-08-01

    In the present study, a novel chemical route is used to synthesize the undoped and Cu-doped ZnO thin films in aqueous solution by successive ionic layer adsorption and reaction (SILAR) method. The synthesized thin films are characterized by x-ray diffractometer (XRD), field emission scanning electron microscopy (FE-SEM), energy dispersive x-ray analysis (EDAX), contact angle goniometer and UV-Vis spectroscopic techniques. XRD study shows that the prepared films are polycrystalline in nature with hexagonal crystal structure. The change in morphology for different doping is observed in the studies of FE-SEM. EDAX spectrum shows that the thin films consist of zinc, copper and oxygen elements. Contact angle goniometer is used to measure the contact angle between a liquid and a solid interface and after detection, the nature of the films is initiated from hydrophobic to hydrophilic. The optical band gap energy for direct allowed transition ranging between 1.60-2.91 eV is observed.

  13. The structural properties of flower-like ZnO nanostructures on porous silicon

    NASA Astrophysics Data System (ADS)

    Eswar, Kevin Alvin; Suhaimi, Mohd Husairi Fadzillah; Guliling, Muliyadi; Mohamad, Maryam; Khusaimi, Zuraida; Rusop, M.; Abdullah, Saifollah

    2018-05-01

    The flower-like zinc oxide (ZnO) were successfully synthesized on porous silicon (PSi) via hydrothermal method. The characteristic of ZnO nanostructures was investigated using field emission scanning microscopy (FESEM) and X-ray diffraction (X-Ray). The FESEM images show the flower-like ZnO nanostructures composed ZnO nanoparticles. The X-ray diffraction shows that strong intensity of (100), (002) and (101) peaks. The structural analysis revealed that the peaks angles were shifted due to the stress or imperfection of the crystalline of ZnO nanostructures. The crystalline sizes in range of 42.60 to 54.09 nm were produced.

  14. Effect of morphology on the non-ohmic conduction in ZnO nanostructures

    NASA Astrophysics Data System (ADS)

    Praveen, E.; Jayakumar, K.

    2016-05-01

    Nanostructures of ZnO is synthesized with nanoflower like morphology by simple wet chemical method. The structural, morphological and electrical characterization have been carried out. The temperature dependent electrical characterization of ZnO pellets of thickness 1150 µm is made by the application of 925MPa pressure. The morphological dependence of non-ohmic conduction beyond some arbitrary tunneling potential and grain boundary barrier thickness is compared with the commercially available bulk ZnO. Our results show the suitability of nano-flower like ZnO for the devices like sensors, rectifiers etc.

  15. Hydrothermal Synthesis of Various Hierarchical ZnO Nanostructures and Their Methane Sensing Properties

    PubMed Central

    Zhou, Qu; Chen, Weigen; Xu, Lingna; Peng, Shudi

    2013-01-01

    Hierarchical flower-like ZnO nanorods, net-like ZnO nanofibers and ZnO nanobulks have been successfully synthesized via a surfactant assisted hydrothemal method. The synthesized products were characterized by X-ray powder diffraction and field emission scanning electron microscopy, respectively. A possible growth mechanism of the various hierarchical ZnO nanostructures is discussed in detail. Gas sensors based on the as-prepared ZnO nanostructures were fabricated by screen-printing on a flat ceramic substrate. Furthermore, their gas sensing characteristics towards methane were systematically investigated. Methane is an important characteristic hydrocarbon contaminant found dissolved in power transformer oil as a result of faults. We find that the hierarchical flower-like ZnO nanorods and net-like ZnO nanofibers samples show higher gas response and lower operating temperature with rapid response-recovery time compared to those of sensors based on ZnO nanobulks. These results present a feasible way of exploring high performance sensing materials for on-site detection of characteristic fault gases dissolved in transformer oil. PMID:23666136

  16. The SL-assisted synthesis of hierarchical ZnO nanostructures and their enhanced photocatalytic activity

    NASA Astrophysics Data System (ADS)

    Miao, Ting-Ting; Guo, Yuan-Ru; Pan, Qing-Jiang

    2013-06-01

    Hierarchical ZnO nanoparticle-bar, nanomesh-lamina, and quasi-nanosphere structures have been successfully synthesized by the precipitation method with assistance of sodium lignosulphonate (SL). It is shown that the obtained ZnO nanomaterials are well crystallized and possess hexagonal wurtzite structure after calcination. Morphologies of ZnO with particle sizes ranging from 50 to 200 nm can be fabricated by tuning the SL amount in our synthetic route. Plenty of pores have been observed both in nanoparticle-bar and nanomesh-lamina ZnO. This may provide scaffold microenvironments to enhance their photocatalytic activity. It is evident that the synthesized ZnO exhibits good photocatalytic activity of degrading methylene blue, even under a very low-power UV illumination, which allows for the treatment of wastewater containing organic pollutants in an effective way. Among our synthesized nanomaterials, the nanomesh-lamina ZnO has the highest photodegradation efficiency, achieving nearly 100 % degradation only within 1.5 h (UV irradiation power of 12 W). As these ZnO nanomaterials are simply synthesized using SL which is a pulp industry by-product and their intrinsic hierarchical nanostructures show outstanding photocatalytic behavior, we expect the present controllable, environment-friendly, and cost-effective approach to be applied in the synthesis of small-sized ZnO materials.

  17. Formation of quasi-single crystalline porous ZnO nanostructures with a single large cavity

    NASA Astrophysics Data System (ADS)

    Cho, Seungho; Kim, Semi; Jung, Dae-Won; Lee, Kun-Hong

    2011-09-01

    We report a method for synthesizing quasi-single crystalline porous ZnO nanostructures containing a single large cavity. The microwave-assisted route consists of a short (about 2 min) temperature ramping stage (from room temperature to 120 °C) and a stage in which the temperature is maintained at 120 °C for 2 h. The structures produced by this route were 200-480 nm in diameter. The morphological yields of this method were very high. The temperature- and time-dependent evolution of the synthesized powders and the effects of an additive, vitamin C, were studied. Spherical amorphous/polycrystalline structures (70-170 nm in diameter), which appeared transitorily, may play a key role in the formation of the single crystalline porous hollow ZnO nanostructures. Studies and characterization of the nanostructures suggested a possible mechanism for formation of the quasi-single crystalline porous ZnO nanostructures with an interior space.We report a method for synthesizing quasi-single crystalline porous ZnO nanostructures containing a single large cavity. The microwave-assisted route consists of a short (about 2 min) temperature ramping stage (from room temperature to 120 °C) and a stage in which the temperature is maintained at 120 °C for 2 h. The structures produced by this route were 200-480 nm in diameter. The morphological yields of this method were very high. The temperature- and time-dependent evolution of the synthesized powders and the effects of an additive, vitamin C, were studied. Spherical amorphous/polycrystalline structures (70-170 nm in diameter), which appeared transitorily, may play a key role in the formation of the single crystalline porous hollow ZnO nanostructures. Studies and characterization of the nanostructures suggested a possible mechanism for formation of the quasi-single crystalline porous ZnO nanostructures with an interior space. Electronic supplementary information (ESI) available: TEM images and the corresponding SAED image of a ZnO

  18. ZnO synthesized in air by fs laser irradiation on metallic Zn thin films

    NASA Astrophysics Data System (ADS)

    Esqueda-Barrón, Y.; Herrera, M.; Camacho-López, S.

    2018-05-01

    We present results on rapid femtosecond laser synthesis of nanostructured ZnO. We used metallic Zn thin films to laser scan along straight tracks, until forming nanostructured ZnO. The synthesis dependence on laser irradiation parameters such as the per pulse fluence, integrated fluence, laser scan speed, and number of scans were explored carefully. SEM characterization showed that the morphology of the obtained ZnO is dictated by the integrated fluence and the laser scan speed; micro Raman and XRD results allowed to identify optimal laser processing conditions for getting good quality ZnO; and cathodoluminescence measurements demonstrated that a single laser scan at high per pulse laser fluence, but a medium integrated laser fluence and a medium laser scan speed favors a low density of point-defects in the lattice. Electrical measurements showed a correlation between resistivity of the laser produced ZnO and point-defects created during the synthesis. Transmittance measurements showed that, the synthesized ZnO can reach down to the supporting fused silica substrate under the right laser irradiation conditions. The physical mechanism for the formation of ZnO, under ultrashort pulse laser irradiation, is discussed in view of the distinct times scales given by the laser pulse duration and the laser pulse repetition rate.

  19. Hierarchical structures of ZnO spherical particles synthesized solvothermally

    NASA Astrophysics Data System (ADS)

    Saito, Noriko; Haneda, Hajime

    2011-12-01

    We review the solvothermal synthesis, using a mixture of ethylene glycol (EG) and water as the solvent, of zinc oxide (ZnO) particles having spherical and flower-like shapes and hierarchical nanostructures. The preparation conditions of the ZnO particles and the microscopic characterization of the morphology are summarized. We found the following three effects of the ratio of EG to water on the formation of hierarchical structures: (i) EG restricts the growth of ZnO microcrystals, (ii) EG promotes the self-assembly of small crystallites into spheroidal particles and (iii) the high water content of EG results in hollow spheres.

  20. A flexible UV nanosensor based on reduced graphene oxide decorated ZnO nanostructures

    NASA Astrophysics Data System (ADS)

    Wang, Zhenxing; Zhan, Xueying; Wang, Yajun; Muhammad, Safdar; Huang, Ying; He, Jun

    2012-03-01

    A low-cost, compatible with flexible electronics, high performance UV sensor has been achieved from a reduced graphene oxide (RGO) decorated hydrangea-like ZnO film on a PDMS substrate. The hydrangea-like ZnO UV sensor has the best UV sensing performance among devices made of three kinds of ZnO nanostructures synthesized by a hydrothermal method, and demonstrated a dramatic enhancement in on/off ratio and photoresponse current by introducing an appropriate weight ratio of RGO. The on/off ratio of the 0.05% RGO/ZnO sensor increases almost one order of magnitude compared to that of a pristine hydrangea-like ZnO UV sensor. While for the 5% RGO decorated ZnO sensor, the photoresponse current reaches as high as ~1 μA and exceeds 700 times that of a ZnO UV sensor. These results indicate that RGO is an appropriate material to enhance the performance of ZnO nanostructure UV sensors based on its unique features, especially the high optical transparency and excellent electronic conductivity. Our findings will make RGO/ZnO nanohybrids extraordinarily promising in optoelectronics, flexible electronics and sensor applications.

  1. A flexible UV nanosensor based on reduced graphene oxide decorated ZnO nanostructures.

    PubMed

    Wang, Zhenxing; Zhan, Xueying; Wang, Yajun; Muhammad, Safdar; Huang, Ying; He, Jun

    2012-04-21

    A low-cost, compatible with flexible electronics, high performance UV sensor has been achieved from a reduced graphene oxide (RGO) decorated hydrangea-like ZnO film on a PDMS substrate. The hydrangea-like ZnO UV sensor has the best UV sensing performance among devices made of three kinds of ZnO nanostructures synthesized by a hydrothermal method, and demonstrated a dramatic enhancement in on/off ratio and photoresponse current by introducing an appropriate weight ratio of RGO. The on/off ratio of the 0.05% RGO/ZnO sensor increases almost one order of magnitude compared to that of a pristine hydrangea-like ZnO UV sensor. While for the 5% RGO decorated ZnO sensor, the photoresponse current reaches as high as ∼1 μA and exceeds 700 times that of a ZnO UV sensor. These results indicate that RGO is an appropriate material to enhance the performance of ZnO nanostructure UV sensors based on its unique features, especially the high optical transparency and excellent electronic conductivity. Our findings will make RGO/ZnO nanohybrids extraordinarily promising in optoelectronics, flexible electronics and sensor applications.

  2. Fast synthesize ZnO quantum dots via ultrasonic method.

    PubMed

    Yang, Weimin; Zhang, Bing; Ding, Nan; Ding, Wenhao; Wang, Lixi; Yu, Mingxun; Zhang, Qitu

    2016-05-01

    Green emission ZnO quantum dots were synthesized by an ultrasonic sol-gel method. The ZnO quantum dots were synthesized in various ultrasonic temperature and time. Photoluminescence properties of these ZnO quantum dots were measured. Time-resolved photoluminescence decay spectra were also taken to discover the change of defects amount during the reaction. Both ultrasonic temperature and time could affect the type and amount of defects in ZnO quantum dots. Total defects of ZnO quantum dots decreased with the increasing of ultrasonic temperature and time. The dangling bonds defects disappeared faster than the optical defects. Types of optical defects first changed from oxygen interstitial defects to oxygen vacancy and zinc interstitial defects. Then transformed back to oxygen interstitial defects again. The sizes of ZnO quantum dots would be controlled by both ultrasonic temperature and time as well. That is, with the increasing of ultrasonic temperature and time, the sizes of ZnO quantum dots first decreased then increased. Moreover, concentrated raw materials solution brought larger sizes and more optical defects of ZnO quantum dots. Copyright © 2015 Elsevier B.V. All rights reserved.

  3. Advanced thermopower wave in novel ZnO nanostructures/fuel composite.

    PubMed

    Lee, Kang Yeol; Hwang, Hayoung; Choi, Wonjoon

    2014-09-10

    Thermopower wave is a new concept of energy conversion from chemical to thermal to electrical energy, produced from the chemical reaction in well-designed hybrid structures between nanomaterials and combustible fuels. The enhancement and optimization of energy generation is essential to make it useful for future applications. In this study, we demonstrate that simple solution-based synthesized zinc oxide (ZnO) nanostructures, such as nanorods and nanoparticles are capable of generating high output voltage from thermopower waves. In particular, an astonishing improvement in the output voltage (up to 3 V; average 2.3 V) was achieved in a ZnO nanorods-based composite film with a solid fuel (collodion, 5% nitrocellulose), which generated an exothermic chemical reaction. Detailed analyses of thermopower waves in ZnO nanorods- and cube-like nanoparticles-based hybrid composites have been reported in which nanostructures, output voltage profile, wave propagation velocities, and surface temperature have been characterized. The average combustion velocities for a ZnO nanorods/fuel and a ZnO cube-like nanoparticles/fuel composites were 40.3 and 30.0 mm/s, while the average output voltages for these composites were 2.3 and 1.73 V. The high output voltage was attributed to the amplified temperature in intermixed composite of ZnO nanostructures and fuel due to the confined diffusive heat transfer in nanostructures. Moreover, the extended interfacial areas between ZnO nanorods and fuel induced large amplification in the dynamic change of the chemical potential, and it resulted in the enhanced output voltage. The differences of reaction velocity and the output voltage between ZnO nanorods- and ZnO cube-like nanoparticles-based composites were attributed to variations in electron mobility and grain boundary, as well as thermal conductivities of ZnO nanorods and particles. Understanding this astonishing increase and the variation of the output voltage and reaction velocity, precise

  4. ZnO Nanostructures for Tissue Engineering Applications

    PubMed Central

    Laurenti, Marco; Cauda, Valentina

    2017-01-01

    This review focuses on the most recent applications of zinc oxide (ZnO) nanostructures for tissue engineering. ZnO is one of the most investigated metal oxides, thanks to its multifunctional properties coupled with the ease of preparing various morphologies, such as nanowires, nanorods, and nanoparticles. Most ZnO applications are based on its semiconducting, catalytic and piezoelectric properties. However, several works have highlighted that ZnO nanostructures may successfully promote the growth, proliferation and differentiation of several cell lines, in combination with the rise of promising antibacterial activities. In particular, osteogenesis and angiogenesis have been effectively demonstrated in numerous cases. Such peculiarities have been observed both for pure nanostructured ZnO scaffolds as well as for three-dimensional ZnO-based hybrid composite scaffolds, fabricated by additive manufacturing technologies. Therefore, all these findings suggest that ZnO nanostructures represent a powerful tool in promoting the acceleration of diverse biological processes, finally leading to the formation of new living tissue useful for organ repair. PMID:29113133

  5. Effects of surface morphology on the optical and electrical properties of Schottky diodes of CBD deposited ZnO nanostructures

    NASA Astrophysics Data System (ADS)

    Mwankemwa, Benard S.; Akinkuade, Shadrach; Maabong, Kelebogile; Nel, Jackie M.; Diale, Mmantsae

    2018-04-01

    We report on effect of surface morphology on the optical and electrical properties of chemical bath deposited Zinc oxide (ZnO) nanostructures. ZnO nanostructures were deposited on the seeded conducting indium doped tin oxide substrate positioned in three different directions in the growth solution. Field emission scanning electron microscopy was used to evaluate the morphological properties of the synthesized nanostructures and revealed that the positioning of the substrate in the growth solution affects the surface morphology of the nanostructures. The optical absorbance, photoluminescence and Raman spectroscopy of the resulting nanostructures are discussed. The electrical characterization of the Schottky diode such as barrier height, ideality factor, rectification ratios, reverse saturation current and series resistance were found to depend on the nanostructures morphology. In addition, current transport mechanism in the higher forward bias of the Schottky diode was studied and space charge limited current was found to be the dominant transport mechanism in all samples.

  6. Nanostructured ZnO Films for Room Temperature Ammonia Sensing

    NASA Astrophysics Data System (ADS)

    Dhivya Ponnusamy; Sridharan Madanagurusamy

    2014-09-01

    Zinc oxide (ZnO) thin films have been deposited by a reactive dc magnetron sputtering technique onto a thoroughly cleaned glass substrate at room temperature. X-ray diffraction revealed that the deposited film was polycrystalline in nature. The field emission scanning electron micrograph (FE-SEM) showed the uniform formation of a rugby ball-shaped ZnO nanostructure. Energy dispersive x-ray analysis (EDX) confirmed that the film was stoichiometric and the direct band gap of the film, determined using UV-Vis spectroscopy, was 3.29 eV. The ZnO nanostructured film exhibited better sensing towards ammonia (NH3) at room temperature (˜30°C). The fabricated ZnO film based sensor was capable of detecting NH3 at as low as 5 ppm, and its parameters, such as response, selectivity, stability, and response/recovery time, were also investigated.

  7. Polarization induced conductive AFM on cobalt doped ZnO nanostructures

    NASA Astrophysics Data System (ADS)

    Sahoo, Pradosh Kumar; Mangamma, G.; Rajesh, A.; Kamruddin, M.; Dash, S.

    2017-05-01

    In the present work cobalt doped ZnO (CZO) nanostructures (NS) have been synthesized by of sol-gel and spin coating process. After the crystal phase confirmation by GIXRD and Raman spectroscopy, Conductive Atomic Force Microscopy (C-AFM) measurement was performed on CZO NS which shows the random distribution of electrically conducting zones on the surface of the material exhibiting current in the range 4-170 pA. We provide the possible mechanisms for variation in current distribution essential for quantitative understanding of transport properties of ZnO NS in doped and undoped forms.

  8. Facile Hydrothermal Preparation of ZNO/CO3O4 Heterogeneous Nanostructures and its Photovoltaic Effect

    NASA Astrophysics Data System (ADS)

    Wei, Fanan; Jiang, Minlin; Liu, Lianqing

    2015-07-01

    Photovoltaic technology offers great potential in the replacement of fossil fuel resources, but still suffers from high device fabrication cost. Herein, we attempted to provide a solution to these issues with heterogeneous nanostructures. Firstly, Zinc oxide (ZnO)/cobalt oxide (Co3O4) heterojunction nanowires are prepared through facile fabrication methods. By assembling Co(OH)2 nanoplates on ZnO nanowire arrays, the ZnO/Co3O4 heterogeneous nanostructures are uniformly synthesized on ITO coated glass and wafer. Current (I)-voltage (V) measurement through conductive atomic force microscope shows excellent photovoltaic effect. And, the heterojunction nanostructures shows unprecedented high open circuit voltage. Therefore, the potential application of the heterogeneous nanostructures in solar cells is demonstrated.

  9. Nanostructured ZnO films for potential use in LPG gas sensors

    NASA Astrophysics Data System (ADS)

    Latyshev, V. M.; Berestok, T. O.; Opanasyuk, A. S.; Kornyushchenko, A. S.; Perekrestov, V. I.

    2017-05-01

    The aim of the work was to obtain ZnO nanostructures with heightened surface area and to study relationship between formation method and gas sensor properties towards propane-butane mixture (LPG). In order to synthesize ZnO nanostructures chemical and physical formation methods have been utilized. The first one was chemical bath deposition technology and the second one magnetron sputtering of Zn followed by oxidation. Optimal method and technological parameters corresponding to formation of material with the highest sensor response have been determined experimentally. Dynamical gas sensor response at different temperature values and dependencies of the sensor sensitivity on the temperature at different LPG concentrations in air have been investigated. It has been found, that sensor response depends on the sample morphology and has the highest value for the structure consisting of thin nanowires. The factors that lead to the decrease in the gas sensor operating temperature have been determined.

  10. Impact of nanostructured thin ZnO film in ultraviolet protection

    PubMed Central

    Sasani Ghamsari, Morteza; Alamdari, Sanaz; Han, Wooje; Park, Hyung-Ho

    2017-01-01

    Nanoscale ZnO is one of the best choices for ultraviolet (UV) protection, not only because of its antimicrobial properties but also due to its potential application for UV preservation. However, the behavior of nanostructured thin ZnO films and long-term effects of UV-radiation exposure have not been studied yet. In this study, we investigated the UV-protection ability of sol gel-derived thin ZnO films after different exposure times. Scanning electron microscopy, atomic force microscopy, and UV-visible optical spectroscopy were carried out to study the structure and optical properties of the ZnO films as a function of the UV-irradiation time. The results obtained showed that the prepared thin ZnO films were somewhat transparent under the visible wavelength region and protective against UV radiation. The UV-protection factor was 50+ for the prepared samples, indicating that they were excellent UV protectors. The deposited thin ZnO films demonstrated promising antibacterial potential and significant light absorbance in the UV range. The experimental results suggest that the synthesized samples have potential for applications in the health care field. PMID:28096668

  11. Impact of nanostructured thin ZnO film in ultraviolet protection.

    PubMed

    Sasani Ghamsari, Morteza; Alamdari, Sanaz; Han, Wooje; Park, Hyung-Ho

    2017-01-01

    Nanoscale ZnO is one of the best choices for ultraviolet (UV) protection, not only because of its antimicrobial properties but also due to its potential application for UV preservation. However, the behavior of nanostructured thin ZnO films and long-term effects of UV-radiation exposure have not been studied yet. In this study, we investigated the UV-protection ability of sol gel-derived thin ZnO films after different exposure times. Scanning electron microscopy, atomic force microscopy, and UV-visible optical spectroscopy were carried out to study the structure and optical properties of the ZnO films as a function of the UV-irradiation time. The results obtained showed that the prepared thin ZnO films were somewhat transparent under the visible wavelength region and protective against UV radiation. The UV-protection factor was 50+ for the prepared samples, indicating that they were excellent UV protectors. The deposited thin ZnO films demonstrated promising antibacterial potential and significant light absorbance in the UV range. The experimental results suggest that the synthesized samples have potential for applications in the health care field.

  12. Morphological driven photocatalytic activity of ZnO nanostructures

    NASA Astrophysics Data System (ADS)

    Abbas, Khaldoon N.; Bidin, Noriah

    2017-02-01

    Using a simple combination of pulse laser ablation in liquid and hydrothermal (PLAL-H) approaches, we control the morphology of ZnO nanostructures (ZNSs) to determine the feasibility of their photocatalytic efficacy. These ZNSs are deposited on Si (100) substrates and two different morphologies are achieved. In this synergistic approach, PLAL synthesized NSs are used as a nutrient solution with different pH for further hydrothermal treatment at 110 °C under varying growth time (5, 30 and 60 min). Surface morphology, structure, composition, and optical characteristics of the prepared ZNSs are determined using FESEM, XRD, FTIR and Photoluminescence (PL) and UV-vis absorption measurements. The morphology revealed remarkable transformation from nanorods (NRs)/nanoflowers (NFs) (at pH 7.6) to nanoparticles (NPs)-like (at pH 10.5) structure. XRD patterns showed better polycrystallinity for NPs with enlarged band gap than NR/NF-like structures. Both PL and UV-vis spectral analysis of ZNPs exhibited higher surface area and deep level defects density dependent morphology, where the nutrient pH and growth time variation are found to play a significant role towards structural evolution. Furthermore, the photocatalytic activities of, such ZNSs are evaluated via sunlight driven photo-degradation of methylene blue (MB) dye. The photocatalytic efficiency of ZNPs is demonstrated to be much superior (97.4%) than ZNRs/ZNFs-like morphology (86%). Such enhanced photocatalytic activities of as-synthesized ZNPs is attributed to the synergism of the improved surface area and defects density, which is useful for promoting the adsorption of the MB dye and suppressed surface recombination of photo-generated charge carriers.

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

    PubMed Central

    2013-01-01

    Background A 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. Results The 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. Conclusion Phase-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. PMID:23601826

  14. GaN and ZnO nanostructures

    NASA Astrophysics Data System (ADS)

    Fündling, Sönke; Sökmen, Ünsal; Behrends, Arne; Al-Suleiman, Mohamed Aid Mansur; Merzsch, Stephan; Li, Shunfeng; Bakin, Andrey; Wehmann, Hergo-Heinrich; Waag, Andreas; Lähnemann, Jonas; Jahn, Uwe; Trampert, Achim; Riechert, Henning

    2010-07-01

    GaN and ZnO are both wide band gap semiconductors with interesting properties concerning optoelectronic and sensor device applications. Due to the lack or the high costs of native substrates, alternatives like sapphire, silicon, or silicon carbide are taken, but the resulting lattice and thermal mismatches lead to increased defect densities which reduce the material quality. In contrast, nanostructures with high aspect ratio have lower defect densities as compared to layers. In this work, we give an overview on our results achieved on both ZnO as well as GaN based nanorods. ZnO nanostructures were grown by a wet chemical approach as well as by VPT on different substrates - even on flexible polymers. To compare the growth results we analyzed the structures by XRD and PL and show possible device applications. The GaN nano- and microstructures were grown by metal organic vapor phase epitaxy either in a self- organized process or by selective area growth for a better control of shape and material composition. Finally we take a look onto possible device applications, presenting our attempts, e.g., to build LEDs based on GaN nanostructures.

  15. Nanostructured ZnO - its challenging properties and potential for device applications

    NASA Astrophysics Data System (ADS)

    Dimova-Malinovska, D.

    2017-01-01

    Nanostructured ZnO possessing interesting structural and optical properties offers challenging opportunities for innovative applications. In this lecture the review of the optical and structural properties of ZnO nanostructured layers is presented. It is shown that they have a direct impact on the parameters of devices involving ZnO. An analysis of current trends in the photovoltaic (PV) field shows that improved light harvesting and efficiency of solar cells can be obtained by implementing nanostructured ZnO layers to process advanced solar cell structures. Because of amenability to doping, high chemical stability, sensitivity to different adsorbed gases, nontoxicity and low cost ZnO attracted much attention for application as gas sensors. The sensitivity of nano-grain ZnO gas elements is comparatively high because of the grain-size effect. Application of nanostructured ZnO for gas sensors and for increasing of light harvesting in solar cells is demonstrated.

  16. Synthesis of porous and nonporous ZnO nanobelt, multipod, and hierarchical nanostructure from Zn-HDS

    NASA Astrophysics Data System (ADS)

    Jang, Eue-Soon; Won, Jung-Hee; Kim, Young-Woon; Cheng, Zhen; Choy, Jin-Ho

    2010-08-01

    Zn based hydroxide double salts (Zn-HDS) with an interlayer spacing of 20 Å was produced by dissolving dumbbell-like ZnO crystal. The resulting Zn-HDS with a ribbon-like shape has a suitable morphology to explore the remarkably mild procedure for synthesis of ZnO nanobelts. We found that the intercalated water molecules into the Zn-HDS could play a key role in the ZnO nanobelts porosity. The nonporous ZnO nanobelts were successfully synthesized from the Zn-HDS by soft-solution process at 95 °C through mild dehydration agent as Na 2CO 3. As-synthesized ZnO nanobelts were grown along not only the [0 1 -1 0], but also the [2 -1 -1 0]. On the other hand, the porous ZnO nanobelts were obtained from the Zn-HDS by calcinations at 200 and 400 °C. In addition, flower-like ZnO multipod and hierarchical nanostructures were produced from the Zn-HDS by using of strong dehydration agent (NaOH) through hydrothermal reaction at 150 and 230 °C.

  17. Fabrication of hierarchical ZnO nanostructures on cotton fabric for wearable device applications

    NASA Astrophysics Data System (ADS)

    Pandiyarasan, V.; Suhasini, S.; Archana, J.; Navaneethan, M.; Majumdar, Abhijit; Hayakawa, Y.; Ikeda, H.

    2017-10-01

    We have investigated ZnO nanostructures on cotton fabric (CF) s a flexible material for an application of wearable thermoelectric (TE) power generator which requires super-hydrophobicity, UV protection, and high TE efficiency. Field emission scanning electron microscopy images revealed that the formed ZnO nanostructures have a mixture of nanorods and nanosheets and are uniformly coated on the CF. XRD pattern and Raman spectra revealed that the ZnO nanostructure has a wurtzite structure. Contact angle measurements showed that the ZnO-nanostructures-coated CF possessed a high super hydrophobic nature with an angle of 132.5°. ZnO nanocomposite/CF sample exhibited an excellent UV protection factor 183.84. Seebeck coefficient, electrical resistivity and thermoelectric power factor of the ZnO nanostructures on cotton fabric were evaluated to be 28 μV/K, 0.04 Ω-cm, and 22 μW/m K2, respectively.

  18. Ligand induced ferromagnetism in ZnO nanostructures.

    PubMed

    Wang, Qian; Sun, Qiang; Jena, P

    2008-10-28

    Complementary to the experimental finding that ZnO nanoparticles become ferromagnetic when coated with N and S containing ligands such as dodecylamine and dodecanethiol [Garcia et al., Nano Lett. 7, 1489 (2007)], we provide the first theoretical understanding of the origin of magnetism in ligated ZnO nanoparticles as well as the structural properties of the ligated systems by using density functional theory and generalized gradient approximation for exchange and correlation, and a cluster model for the nanoparticles. We show that N or S atoms of the ligand bind to the Zn sites. The accompanying changes in the Zn-O bond length, hybridization between Zn 4s orbitals with N 2p or S 3p orbitals, and consequently the redistribution of charges between Zn and O atoms result in a magnetic system where the 2p electrons in O and N, and 3p electrons in S sites are spin polarized. Furthermore, the sites nearest to the Zn atom attached to the ligand carry bulk of the magnetic moment. Studies, as a function of cluster size, also illustrate that magnetism resides only on the surface. Our results confirm that the use of ligands can pave a new way for introducing magnetism in ZnO nanostructures, which can be used to develop magnetic sensors to detect N and S containing molecules.

  19. Study of quantum confinement effects in ZnO nanostructures

    NASA Astrophysics Data System (ADS)

    Movlarooy, Tayebeh

    2018-03-01

    Motivation to fact that zinc oxide nanowires and nanotubes with successful synthesis and the mechanism of formation, stability and electronic properties have been investigated; in this study the structural, electronic properties and quantum confinement effects of zinc oxide nanotubes and nanowires with different diameters are discussed. The calculations within density functional theory and the pseudo potential approximation are done. The electronic structure and energy gap for Armchair and zigzag ZnO nanotubes with a diameter of about 4 to 55 Angstrom and ZnO nanowires with a diameter range of 4 to 23 Å is calculated. The results revealed that due to the quantum confinement effects, by reducing the diameter of nanowires and nanotubes, the energy gap increases. Zinc oxide semiconductor nanostructures since having direct band gap with size-dependent and quantum confinement effect are recommended as an appropriate candidate for making nanoscale optoelectronic devices.

  20. Ionic pH and glucose sensors fabricated using hydrothermal ZnO nanostructures

    NASA Astrophysics Data System (ADS)

    Wang, Jyh-Liang; Yang, Po-Yu; Hsieh, Tsang-Yen; Juan, Pi-Chun

    2016-01-01

    Hydrothermally synthesized aluminum-doped ZnO (AZO) nanostructures have been adopted in extended-gate field-effect transistor (EGFET) sensors to demonstrate the sensitive and stable pH and glucose sensing characteristics of AZO-nanostructured EGFET sensors. The AZO-nanostructured EGFET sensors exhibited the following superior pH sensing characteristics: a high current sensitivity of 0.96 µA1/2/pH, a high linearity of 0.9999, less distortion of output waveforms, a small hysteresis width of 4.83 mV, good long-term repeatability, and a wide sensing range from pHs 1 to 13. The glucose sensing characteristics of AZO-nanostructured biosensors exhibited the desired sensitivity of 60.5 µA·cm-2·mM-1 and a linearity of 0.9996 up to 13.9 mM. The attractive characteristics of high sensitivity, high linearity, and repeatability of using ionic AZO-nanostructured EGFET sensors indicate their potential use as electrochemical and disposable biosensors.

  1. Morphology engineering of ZnO nanostructures for high performance supercapacitors: enhanced electrochemistry of ZnO nanocones compared to ZnO nanowires

    NASA Astrophysics Data System (ADS)

    He, Xiaoli; Yoo, Joung Eun; Lee, Min Ho; Bae, Joonho

    2017-06-01

    In this work, the morphology of ZnO nanostructures is engineered to demonstrate enhanced supercapacitor characteristics of ZnO nanocones (NCs) compared to ZnO nanowires (NWs). ZnO NCs are obtained by chemically etching ZnO NWs. Electrochemical characteristics of ZnO NCs and NWs are extensively investigated to demonstrate morphology dependent capacitive performance of one dimensional ZnO nanostructures. Cyclic voltammetry measurements on these two kinds of electrodes in a three-electrode cell confirms that ZnO NCs exhibit a high specific capacitance of 378.5 F g-1 at a scan rate of 20 mV s-1, which is almost twice that of ZnO NWs (191.5 F g-1). The charge-discharge and electrochemical impedance spectroscopy measurements also clearly result in enhanced capacitive performance of NCs as evidenced by higher specific capacitances and lower internal resistance. Asymmetric supercapacitors are fabricated using activated carbon (AC) as the negative electrode and ZnO NWs and NCs as positive electrodes. The ZnO NC⫽AC can deliver a maximum specific capacitance of 126 F g-1 at a current density of 1.33 A g-1 with an energy density of 25.2 W h kg-1 at the power density of 896.44 W kg-1. In contrast, ZnO NW⫽AC displays 63% of the capacitance obtained from the ZnO NC⫽AC supercapacitor. The enhanced performance of NCs is attributed to the higher surface area of ZnO nanostructures after the morphology is altered from NWs to NCs.

  2. Morphology engineering of ZnO nanostructures for high performance supercapacitors: enhanced electrochemistry of ZnO nanocones compared to ZnO nanowires.

    PubMed

    He, Xiaoli; Yoo, Joung Eun; Lee, Min Ho; Bae, Joonho

    2017-06-16

    In this work, the morphology of ZnO nanostructures is engineered to demonstrate enhanced supercapacitor characteristics of ZnO nanocones (NCs) compared to ZnO nanowires (NWs). ZnO NCs are obtained by chemically etching ZnO NWs. Electrochemical characteristics of ZnO NCs and NWs are extensively investigated to demonstrate morphology dependent capacitive performance of one dimensional ZnO nanostructures. Cyclic voltammetry measurements on these two kinds of electrodes in a three-electrode cell confirms that ZnO NCs exhibit a high specific capacitance of 378.5 F g -1 at a scan rate of 20 mV s -1 , which is almost twice that of ZnO NWs (191.5 F g -1 ). The charge-discharge and electrochemical impedance spectroscopy measurements also clearly result in enhanced capacitive performance of NCs as evidenced by higher specific capacitances and lower internal resistance. Asymmetric supercapacitors are fabricated using activated carbon (AC) as the negative electrode and ZnO NWs and NCs as positive electrodes. The ZnO NC⫽AC can deliver a maximum specific capacitance of 126 F g -1 at a current density of 1.33 A g -1 with an energy density of 25.2 W h kg -1 at the power density of 896.44 W kg -1 . In contrast, ZnO NW⫽AC displays 63% of the capacitance obtained from the ZnO NC⫽AC supercapacitor. The enhanced performance of NCs is attributed to the higher surface area of ZnO nanostructures after the morphology is altered from NWs to NCs.

  3. Development of nanostructured ZnO thin film via electrohydrodynamic atomization technique and its photoconductivity characteristics.

    PubMed

    Duraisamy, Navaneethan; Kwon, Ki Rin; Jo, Jeongdai; Choi, Kyung-Hyun

    2014-08-01

    This article presents the non-vacuum technique for the preparation of nanostructured zinc oxide (ZnO) thin film on glass substrate through electrohydrodynamic atomization (EHDA) technique. The detailed process parameters for achieving homogeneous ZnO thin films are clearly discussed. The crystallinity and surface morphology of ZnO thin film are investigated by X-ray diffraction and field emission scanning electron microscopy. The result shows that the deposited ZnO thin film is oriented in the wurtzite phase with void free surface morphology. The surface roughness of deposited ZnO thin film is found to be ~17.8 nm. The optical properties of nanostructured ZnO thin films show the average transmittance is about 90% in the visible region and the energy band gap is found to be 3.17 eV. The surface chemistry and purity of deposited ZnO thin films are analyzed by fourier transform infrared and X-ray photoelectron spectroscopy, conforming the presence of Zn-O in the deposited thin films without any organic moiety. The photocurrent measurement of nanostructured ZnO thin film is examined in the presence of UV light illumination with wavelength of 365 nm. These results suggest that the deposited nanostructured ZnO thin film through EHDA technique possess promising applications in the near future.

  4. Highly sensitive H2 gas sensor of Co doped ZnO nanostructures

    NASA Astrophysics Data System (ADS)

    Bhati, Vijendra Singh; Ranwa, Sapana; Kumar, Mahesh

    2018-04-01

    In this report, the hydrogen gas sensing properties based on Co doped ZnO nanostructures are explored. The undoped and Co doped nanostructures were grown by RF magnetron sputtering system, and its structural, morphological, and hydrogen sensing behavior are investigated. The maximum relative response was occurred by the 2.5% Co doped ZnO nanostructures among undoped and other doped sensors. The enhancement of relative response might be due to large chemisorbed sites formation on the ZnO surface for the reaction to hydrogen gas.

  5. EFFECTS OF Au ON THE GROWTH OF ZnO NANOSTRUCTURES ON Si BY MOCVD

    NASA Astrophysics Data System (ADS)

    Cong, Chen; Fan, Lu Yang; Ping, He Hai; Wei, Wu Ke; Zhen, Ye Zhi

    2013-06-01

    The effects of Au on the growth of ZnO nanostructures on Si by metal organic chemical vapor deposition (MOCVD) at a relatively low temperature (450°C) were investigated. The experimental results showed that Au nanoparticles played a critical role during the growth of the ZnO nanostructures and affected their morphology and optical properties. It was found that Au nanoparticles particularly affected the nucleation of ZnO nanostructures during the growth process and the Au-assisted growth mechanism of ZnO nanostructures should be ascribed to the vapor-solid (VS) mechanism. The formation of a nanoneedle may be attributed to a more reactive interface between Au and ZnO, which leads to more zinc gaseous species absorbed near the interface. Different nucleation sites on ZnO nuclei resulted in the disorder of ZnO nanoneedles. Moreover, the crystalline quality of nano-ZnO was improved due to the presence of Au, according to the smaller full width at half maximum (FWHM) of the low-temperature exciton emission. We confirmed that ZnO nanoneedles showed better crystalline quality than ZnO nanorods through the HRTEM images and the SAED patterns. The reason for the improvement of the crystalline quality of nano-ZnO may be due to the less lattice mismatch.

  6. Influences of Co doping on the structural and optical properties of ZnO nanostructured

    NASA Astrophysics Data System (ADS)

    Majeed Khan, M. A.; Wasi Khan, M.; Alhoshan, Mansour; Alsalhi, M. S.; Aldwayyan, A. S.

    2010-07-01

    Pure and Co-doped ZnO nanostructured samples have been synthesized by a chemical route. We have studied the structural and optical properties of the samples by using X-ray diffraction (XRD), field-emission scanning electron microscopy (FESEM), field-emission transmission electron microscope (FETEM), energy-dispersive X-ray (EDX) analysis and UV-VIS spectroscopy. The XRD patterns show that all the samples are hexagonal wurtzite structures. Changes in crystallite size due to mechanical activation were also determined from X-ray measurements. These results were correlated with changes in particle size followed by SEM and TEM. The average crystallite sizes obtained from XRD were between 20 to 25 nm. The TEM images showed the average particle size of undoped ZnO nanostructure was about 20 nm whereas the smallest average grain size at 3% Co was about 15 nm. Optical parameters such as absorption coefficient ( α), energy band gap ( E g ), the refractive index ( n), and dielectric constants ( σ) have been determined using different methods.

  7. Probing defects in chemically synthesized ZnO nanostrucures by positron annihilation and photoluminescence spectroscopy

    NASA Astrophysics Data System (ADS)

    Chaudhuri, S. K.; Ghosh, Manoranjan; Das, D.; Raychaudhuri, A. K.

    2010-09-01

    The present article describes the size induced changes in the structural arrangement of intrinsic defects present in chemically synthesized ZnO nanoparticles of various sizes. Routine x-ray diffraction and transmission electron microscopy have been performed to determine the shapes and sizes of the nanocrystalline ZnO samples. Detailed studies using positron annihilation spectroscopy reveals the presence of zinc vacancy. Whereas analysis of photoluminescence results predict the signature of charged oxygen vacancies. The size induced changes in positron parameters as well as the photoluminescence properties, has shown contrasting or nonmonotonous trends as size varies from 4 to 85 nm. Small spherical particles below a critical size (˜23 nm) receive more positive surface charge due to the higher occupancy of the doubly charge oxygen vacancy as compared to the bigger nanostructures where singly charged oxygen vacancy predominates. This electronic alteration has been seen to trigger yet another interesting phenomenon, described as positron confinement inside nanoparticles. Finally, based on all the results, a model of the structural arrangement of the intrinsic defects in the present samples has been reconciled.

  8. Branched nanostructures and method of synthesizing the same

    NASA Technical Reports Server (NTRS)

    Fonseca, Luis F. (Inventor); Sola, Francisco (Inventor); Resto, Oscar (Inventor)

    2009-01-01

    A branched nanostructure is synthesized. A porous material, with pores having a diameter of approximately 1 .mu.m or less, is placed in a vacuum. It is irradiated with an electron beam. This causes a trunk to grow from the porous material and further causes branches to grow from the trunk.

  9. Fabrication of Semiconductor ZnO Nanostructures for Versatile SERS Application

    PubMed Central

    Yang, Lili; Yang, Yong; Ma, Yunfeng; Li, Shuai; Wei, Yuquan; Huang, Zhengren; Long, Nguyen Viet

    2017-01-01

    Since the initial discovery of surface-enhanced Raman scattering (SERS) in the 1970s, it has exhibited a huge potential application in many fields due to its outstanding advantages. Since the ultra-sensitive noble metallic nanostructures have increasingly exposed themselves as having some problems during application, semiconductors have been gradually exploited as one of the critical SERS substrate materials due to their distinctive advantages when compared with noble metals. ZnO is one of the most representative metallic oxide semiconductors with an abundant reserve, various and cost-effective fabrication techniques, as well as special physical and chemical properties. Thanks to the varied morphologies, size-dependent exciton, good chemical stability, a tunable band gap, carrier concentration, and stoichiometry, ZnO nanostructures have the potential to be exploited as SERS substrates. Moreover, other distinctive properties possessed by ZnO such as biocompatibility, photocatcalysis and self-cleaning, and gas- and chemo-sensitivity can be synergistically integrated and exerted with SERS activity to realize the multifunctional potential of ZnO substrates. In this review, we discuss the inevitable development trend of exploiting the potential semiconductor ZnO as a SERS substrate. After clarifying the root cause of the great disparity between the enhancement factor (EF) of noble metals and that of ZnO nanostructures, two specific methods are put forward to improve the SERS activity of ZnO, namely: elemental doping and combination of ZnO with noble metals. Then, we introduce a distinctive advantage of ZnO as SERS substrate and illustrate the necessity of reporting a meaningful average EF. We also summarize some fabrication methods for ZnO nanostructures with varied dimensions (0–3 dimensions). Finally, we present an overview of ZnO nanostructures for the versatile SERS application. PMID:29156600

  10. Fabrication of nanostructured Al-doped ZnO thin film for methane sensing applications

    SciTech Connect

    Shafura, A. K., E-mail: shafura@ymail.com; Azhar, N. E. I.; Uzer, M.

    2016-07-06

    CH{sub 4} gas sensor was fabricated using spin-coating method of the nanostructured ZnO thin film. Effect of annealing temperature on the electrical and structural properties of the film was investigated. Dense nanostructured ZnO film are obtained at higher annealing temperature. The optimal condition of annealing temperature is 500°C which has conductivity and sensitivity value of 3.3 × 10{sup −3} S/cm and 11.5%, respectively.

  11. Round-patterned ZnO nanostructure coated with siloxane-based polymer for nerve agent detection

    NASA Astrophysics Data System (ADS)

    Choi, Hyun Ji; Lee, Ji Won; Jeong, Dong-Cheol; Ha, Seonggyun; Song, Changsik; Boo, Jin-Hyo

    2018-01-01

    The alignment of zinc oxide (ZnO) nanostructures is expected to improve device sensitivities due to large surface areas which can be utilized to capture significant quantities of gas particles. In this study, we investigated patterned ZnO nanorods modified with polystyrene monolayers synthesized directly onto a quartz crystal microbalance (QCM) cell to increase the coating surface area of the sensing material. Also, we designed and synthesized a siloxane-based polymer (S1 polymer) as a sensing material. The patterned ZnO nanorods coated with S1 polymers were fabricated and used for the detection of dimethyl methylphosphonate (DMMP). The resonance frequency of QCM was shifted due to the adsorption and desorption of a compound at the surface of the modified electrodes. We have synthesized an S1 polymer that exhibited high sensitivity to DMMP. The patterned ZnO nanorods coated with the polymer also exhibited improved sensitivity due to an enhanced surface area capable of adsorbing more DMMP vapor.

  12. Eosin-Y sensitized core-shell TiO2-ZnO nano-structured photoanodes for dye-sensitized solar cell applications.

    PubMed

    Manikandan, V S; Palai, Akshaya K; Mohanty, Smita; Nayak, Sanjay K

    2018-06-01

    In the current investigation, TiO 2 and TiO 2 -ZnO (core-shell) spherical nanoparticles were synthesized by simple combined hydrolysis and refluxing method. A TiO 2 core nanomaterial on the shell material of ZnO was synthesized by utilizing variable ratios of ZnO. The structural characterization of TiO 2 -ZnO core/shell nanoparticles were done by XRD analysis. The spherical structured morphology of the TiO 2 -ZnO has been confirmed through field emission scanning electron microscopy (FE-SEM) and transmission electron microscopy (TEM) studies. The UV-visible spectra of TiO 2 -ZnO nanostructures were also compared with the pristine TiO 2 to investigate the shift of wavelength. The TiO 2 -ZnO core/shell nanoparticles at the interface efficiently collect the photogenarated electrons from ZnO and also ZnO act a barrier for reduced charge recombination of electrolyte and dye-nanoparticles interface. This combination improved the light absorption which induced the charge transfer ability and dye loading capacity of core-shell nanoparticles. An enhancement in the short circuit current (J sc ) from 1.67 mA/cm 2 to 2.1 mA/cm 2 has been observed for TiO 2 -ZnObased photoanode (with platinum free counter electrode), promises an improvement in the energy conversion efficiency by 57% in comparison with that of the DSSCs based on the pristine TiO 2 . Henceforth, TiO 2 -ZnO photoelectrode in ZnO will effectively act as barrier at the interface of TiO 2 -ZnO and TiO 2 , ensuring the potential for DSSC application. Copyright © 2018 Elsevier B.V. All rights reserved.

  13. Morphology evolution of hierarchical ZnO nanostructures modulated by supersaturation and growth temperature

    NASA Astrophysics Data System (ADS)

    Yan, Youguo; Zhou, Lixia; Yu, Lianqing; Zhang, Ye

    2008-07-01

    Three kinds of ZnO hierarchical structures, nanocombs with tube- and needle-shaped teeth and hierarchical nanorod arrays, were successfully synthesized through the chemical vapor deposition method. Combining the experimental parameters, the microcosmic growing conditions (growth temperature and supersaturation) along the flux was discussed at length, and, based on the conclusions, three reasonable growth processes were proposed. The results and discussions were beneficial to further realize the relation between the growing behavior of the nanomaterial and microcosmic conditions, and the hierarchical nanostructures obtained were also expected to have potential applications as functional blocks in future nanodevices. Furthermore, the study of photoluminescence further indicated that the physical properties were strongly dependent on the crystal structure.

  14. High quantum yield ZnO quantum dots synthesizing via an ultrasonication microreactor method.

    PubMed

    Yang, Weimin; Yang, Huafang; Ding, Wenhao; Zhang, Bing; Zhang, Le; Wang, Lixi; Yu, Mingxun; Zhang, Qitu

    2016-11-01

    Green emission ZnO quantum dots were synthesized by an ultrasonic microreactor. Ultrasonic radiation brought bubbles through ultrasonic cavitation. These bubbles built microreactor inside the microreactor. The photoluminescence properties of ZnO quantum dots synthesized with different flow rate, ultrasonic power and temperature were discussed. Flow rate, ultrasonic power and temperature would influence the type and quantity of defects in ZnO quantum dots. The sizes of ZnO quantum dots would be controlled by those conditions as well. Flow rate affected the reaction time. With the increasing of flow rate, the sizes of ZnO quantum dots decreased and the quantum yields first increased then decreased. Ultrasonic power changed the ultrasonic cavitation intensity, which affected the reaction energy and the separation of the solution. With the increasing of ultrasonic power, sizes of ZnO quantum dots first decreased then increased, while the quantum yields kept increasing. The effect of ultrasonic temperature on the photoluminescence properties of ZnO quantum dots was influenced by the flow rate. Different flow rate related to opposite changing trend. Moreover, the quantum yields of ZnO QDs synthesized by ultrasonic microreactor could reach 64.7%, which is higher than those synthesized only under ultrasonic radiation or only by microreactor. Copyright © 2016 Elsevier B.V. All rights reserved.

  15. Controlled Growth of Parallel Oriented ZnO Nanostructural Arrays on Ga2O3 Nanowires

    DTIC Science & Technology

    2008-11-01

    Controlled Growth of Parallel Oriented ZnO Nanostructural Arrays on Ga2O3 Nanowires Lena Mazeina,* Yoosuf N. Picard, and Sharka M. Prokes Electronics...Manuscript ReceiVed NoVember 6, 2008 ABSTRACT: Novel hierarchical ZnO- Ga2O3 nanostructures were fabricated via a two stage growth process. Nanowires of Ga2O3 ...nanobrushes (NBs) with Ga2O3 as the core and ZnO as the branches self-assembling symmetrically in six equiangular directions around the core

  16. Internal stress induced natural self-chemisorption of ZnO nanostructured films

    PubMed Central

    Chi, Po-Wei; Su, Chih-Wei; Wei, Da-Hua

    2017-01-01

    The energetic particles bombardment can produce large internal stress in the zinc oxide (ZnO) thin film, and it can be used to intentionally modify the surface characteristics of ZnO films. In this article, we observed that the internal stress increased from −1.62 GPa to −0.33 GPa, and the naturally wettability of the textured ZnO nanostructured films changed from hydrophobicity to hydrophilicity. According to analysis of surface chemical states, the naturally controllable wetting behavior can be attributed to hydrocarbon adsorbates on the nanostructured film surface, which is caused by tunable internal stress. On the other hand, the interfacial water molecules near the surface of ZnO nanostructured films have been identified as hydrophobic hydrogen structure by Fourier transform infrared/attenuated total reflection. Moreover, a remarkable near-band-edge emission peak shifting also can be observed in PL spectra due to the transition of internal stress state. Furthermore, our present ZnO nanostructured films also exhibited excellent transparency over 80% with a wise surface wetting switched from hydrophobic to hydrophilic states after exposing in ultraviolet (UV) surroundings. Our work demonstrated that the internal stress of the thin film not only induced natural wettability transition of ZnO nanostructured films, but also in turn affected the surface properties such as surface chemisorption. PMID:28233827

  17. Internal stress induced natural self-chemisorption of ZnO nanostructured films

    NASA Astrophysics Data System (ADS)

    Chi, Po-Wei; Su, Chih-Wei; Wei, Da-Hua

    2017-02-01

    The energetic particles bombardment can produce large internal stress in the zinc oxide (ZnO) thin film, and it can be used to intentionally modify the surface characteristics of ZnO films. In this article, we observed that the internal stress increased from -1.62 GPa to -0.33 GPa, and the naturally wettability of the textured ZnO nanostructured films changed from hydrophobicity to hydrophilicity. According to analysis of surface chemical states, the naturally controllable wetting behavior can be attributed to hydrocarbon adsorbates on the nanostructured film surface, which is caused by tunable internal stress. On the other hand, the interfacial water molecules near the surface of ZnO nanostructured films have been identified as hydrophobic hydrogen structure by Fourier transform infrared/attenuated total reflection. Moreover, a remarkable near-band-edge emission peak shifting also can be observed in PL spectra due to the transition of internal stress state. Furthermore, our present ZnO nanostructured films also exhibited excellent transparency over 80% with a wise surface wetting switched from hydrophobic to hydrophilic states after exposing in ultraviolet (UV) surroundings. Our work demonstrated that the internal stress of the thin film not only induced natural wettability transition of ZnO nanostructured films, but also in turn affected the surface properties such as surface chemisorption.

  18. Internal stress induced natural self-chemisorption of ZnO nanostructured films.

    PubMed

    Chi, Po-Wei; Su, Chih-Wei; Wei, Da-Hua

    2017-02-24

    The energetic particles bombardment can produce large internal stress in the zinc oxide (ZnO) thin film, and it can be used to intentionally modify the surface characteristics of ZnO films. In this article, we observed that the internal stress increased from -1.62 GPa to -0.33 GPa, and the naturally wettability of the textured ZnO nanostructured films changed from hydrophobicity to hydrophilicity. According to analysis of surface chemical states, the naturally controllable wetting behavior can be attributed to hydrocarbon adsorbates on the nanostructured film surface, which is caused by tunable internal stress. On the other hand, the interfacial water molecules near the surface of ZnO nanostructured films have been identified as hydrophobic hydrogen structure by Fourier transform infrared/attenuated total reflection. Moreover, a remarkable near-band-edge emission peak shifting also can be observed in PL spectra due to the transition of internal stress state. Furthermore, our present ZnO nanostructured films also exhibited excellent transparency over 80% with a wise surface wetting switched from hydrophobic to hydrophilic states after exposing in ultraviolet (UV) surroundings. Our work demonstrated that the internal stress of the thin film not only induced natural wettability transition of ZnO nanostructured films, but also in turn affected the surface properties such as surface chemisorption.

  19. The use of novel biodegradable, optically active and nanostructured poly(amide-ester-imide) as a polymer matrix for preparation of modified ZnO based bionanocomposites

    SciTech Connect

    Abdolmaleki, Amir, E-mail: abdolmaleki@cc.iut.ac.ir; Nanotechnology and Advanced Materials Institute, Isfahan University of Technology, Isfahan 84156-83111, Islamic Republic of Iran; Mallakpour, Shadpour, E-mail: mallak@cc.iut.ac.ir

    Highlights: Black-Right-Pointing-Pointer A novel biodegradable and nanostructured PAEI based on two amino acids, was synthesized. Black-Right-Pointing-Pointer ZnO nanoparticles were modified via two different silane coupling agents. Black-Right-Pointing-Pointer PAEI/modified ZnO BNCs were synthesized through ultrasound irradiation. Black-Right-Pointing-Pointer ZnO particles were dispersed homogeneously in PAEI matrix on nanoscale. Black-Right-Pointing-Pointer The effect of ZnO nanoparticles on the properties of synthesized polymer was examined. -- Abstract: A novel biodegradable and nanostructured poly(amide-ester-imide) (PAEI) based on two different amino acids, was synthesized via direct polycondensation of biodegradable N,N Prime -bis[2-(methyl-3-(4-hydroxyphenyl)propanoate)]isophthaldiamide and N,N Prime -(pyromellitoyl)-bis-L-phenylalanine diacid. The resulting polymer was characterized by FT-IR, {sup 1}H NMR,more » specific rotation, elemental analysis, thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), X-ray diffraction (XRD) and field emission scanning electron microscopy (FE-SEM) analysis. The synthesized polymer showed good thermal stability with nano and sphere structure. Then PAEI/ZnO bionanocomposites (BNCs) were fabricated via interaction of pure PAEI and ZnO nanoparticles. The surface of ZnO was modified with two different silane coupling agents. PAEI/ZnO BNCs were studied and characterized by FT-IR, XRD, UV/vis, FE-SEM and TEM. The TEM and FE-SEM results indicated that the nanoparticles were dispersed homogeneously in PAEI matrix on nanoscale. Furthermore the effect of ZnO nanoparticle on the thermal stability of the polymer was investigated with TGA and DSC technique.« less

  20. Effects of surface morphology of ZnO seed layers on growth of ZnO nanostructures prepared by hydrothermal method and annealing.

    PubMed

    Yim, Kwang Gug; Kim, Min Su; Leem, Jae-Young

    2013-05-01

    ZnO nanostructures were grown on Si (111) substrates by a hydrothermal method. Prior to growing the ZnO nanostructures, ZnO seed layers with different post-heat temperatures were prepared by a spin-coating process. Then, the ZnO nanostructures were annealed at 500 degrees C for 20 min under an Ar atmosphere. Scanning electron microscopy (SEM), X-ray diffraction (XRD), and photoluminescence (PL) were carried out at room temperature (RT) to investigate the structural and optical properties of the as-grown and annealed ZnO nanostructures. The surface morphologies of the seed layers changed from a smooth surface to a mountain chain-like structure as the post-heating temperatures increased. The as-grown and annealed ZnO nanostructures exhibited a strong (002) diffraction peak. Compared to the as-grown ZnO nanostructures, the annealed ZnO nanostructures exhibited significantly strong enhancement in the PL intensity ratio by almost a factor of 2.

  1. Low-temperature synthesis of rose-like ZnO nanostructures using surfactin and their photocatalytic activity.

    PubMed

    Reddy, A Satyanarayana; Kuo, Yi-Hao; Atla, Shashi B; Chen, Chien-Yen; Chen, Chien-Cheng; Shih, Ruey-Chyuan; Chang, Young-Fo; Maity, Jyoti Prakash; Chen, How-Ji

    2011-06-01

    Rose-like ZnO nanostructures were synthesized by the precipitation method using a biosurfactant (surfactin) as a templating-agent stabilizer. The concentration of surfactin in the precursor solution significantly influenced the thickness and density of the petals in the rose-like structures, and all samples were of a wurtzite phase. The thickness of the petal was found to decrease with increasing surfactin concentration. The average thickness of the petals was found to be between 10 and 13 nm. Photocatalytic degradation of methylene blue using rose-like ZnO nanostuctures was investigated, and the morphology, density and thickness of the ZnO petals were found to influence the photodegradation activity. The samples with loosely-spread petals, or plate-like ZnO structures, brought about the strongest photodegradation in comparison with the dense rose-like structures. The greater activity of the loose-petal structures was correlated with their higher absorption in the UV region in comparison with the other samples. The ZnO samples prepared using low surfactin concentrations had higher rate constant values, i.e., 9.1 x 10(-3) min(-1), which revealed that the photodegradation of methylene blue under UV irradiation progressed by a pseudo first-order kinetic reaction.

  2. Toxicity evaluation of ZnO nanostructures on L929 fibroblast cell line using MTS assay

    NASA Astrophysics Data System (ADS)

    Bakhori, Siti Khadijah Mohd; Mahmud, Shahrom; Ann, Ling Chuo; Mohamed, Azman Seeni; Saifuddin, Siti Nazmin; Masudi, Sam'an Malik; Mohamad, Dasmawati

    2015-04-01

    ZnO has wide applications in medical and dentistry apart from being used as optoelectronic devices such as solar cells, photodetectors, sensors and light emitting diodes (LEDs). Therefore, the toxicity evaluation is important to know the toxicity level on normal cell line. The toxicity of two grades ZnO nanostructures, ZnO-4 and ZnO-8 have been carried out using cytotoxicity test of MTS assay on L929 rat fibroblast cell line. Prior to that, ZnO-4 and ZnO-8 were characterized for its morphology, structure and optical properties using FESEM, X-ray diffraction, and Photoluminescence respectively. The two groups revealed difference in morphology and exhibit slightly shifted of near band edge emission of Photoluminescence other than having a similar calculated crystallite size of nanostructures. The viability of cells after 72h were obtained and the statistical significance value was calculated using SPSS v20. The p value is more than 0.05 between untreated and treated cell with ZnO. This insignificant value of p>0.05 can be summarized as a non-toxic level of ZnO-4 and ZnO-8 on the L929 cell line.

  3. Toxicity evaluation of ZnO nanostructures on L929 fibroblast cell line using MTS assay

    SciTech Connect

    Bakhori, Siti Khadijah Mohd; Mahmud, Shahrom; Ann, Ling Chuo

    2015-04-24

    ZnO has wide applications in medical and dentistry apart from being used as optoelectronic devices such as solar cells, photodetectors, sensors and light emitting diodes (LEDs). Therefore, the toxicity evaluation is important to know the toxicity level on normal cell line. The toxicity of two grades ZnO nanostructures, ZnO-4 and ZnO-8 have been carried out using cytotoxicity test of MTS assay on L929 rat fibroblast cell line. Prior to that, ZnO-4 and ZnO-8 were characterized for its morphology, structure and optical properties using FESEM, X-ray diffraction, and Photoluminescence respectively. The two groups revealed difference in morphology and exhibit slightly shiftedmore » of near band edge emission of Photoluminescence other than having a similar calculated crystallite size of nanostructures. The viability of cells after 72h were obtained and the statistical significance value was calculated using SPSS v20. The p value is more than 0.05 between untreated and treated cell with ZnO. This insignificant value of p>0.05 can be summarized as a non-toxic level of ZnO-4 and ZnO-8 on the L929 cell line.« less

  4. Nanostructured ZnO films on stainless steel are highly safe and effective for antimicrobial applications.

    PubMed

    Shim, Kyudae; Abdellatif, Mohamed; Choi, Eunsoo; Kim, Dongkyun

    2017-04-01

    The safety and effectiveness of antimicrobial ZnO films must be established for general applications. In this study, the antimicrobial activity, skin irritation, elution behavior, and mechanical properties of nanostructured ZnO films on stainless steel were evaluated. ZnO nanoparticle (NP) and ZnO nanowall (NW) structures were prepared with different surface roughnesses, wettability, and concentrations using an RF magnetron sputtering system. The thicknesses of ZnO NP and ZnO NW were approximately 300 and 620 nm, respectively, and ZnO NW had two diffraction directions of [0002] and [01-10] based on high-resolution transmission electron microscopy. The ZnO NW structure demonstrated 99.9% antimicrobial inhibition against Escherichia coli, Staphylococcus aureus, and Penicillium funiculosum, and no skin irritation was detected using experimental rabbits. Approximately 27.2 ± 3.0 μg L -1 Zn ions were eluted from the ZnO NW film at 100 °C for 24 h, which satisfies the WHO guidelines for drinking water quality. Furthermore, the Vickers hardness and fracture toughness of ZnO NW films on stainless steel were enhanced by 11 and 14% compared to those of the parent stainless steel. Based on these results, ZnO NW films on STS316L sheets are useful for household supplies, such as water pipes, faucets, and stainless steel containers.

  5. A study on photoelectrochemical properties of ZnO@ZnS nanostructures synthesized via facile ion-exchange approach

    NASA Astrophysics Data System (ADS)

    Sharma, Akash; Sahoo, Pooja; Thangavel, R.

    2018-05-01

    In this work, ZnO nanorods (NRs) were fabricated, on cleaned ITO substrates by using sol-gel spin coating followed by hydrothermal technique. In order to coat zinc sulphide (ZnS) layers on the earlier prepared NRs a facile ion-exchange approach was adopted. The ZnO@ZnS nanostructures so prepared were characterised by using X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), UV-visible spectroscopy and photoelectrochemical study. XRD spectra confirmed the hexagonal wurtzite structure of all the samples along with preferential c-axis orientation. Further it was also observed from the FESEM images that sulfidation process doesn't affect the structure of ZnO NRs arrays. From the absorption spectra it can be clearly observed that the light absorbing property has increased in within the visible range due to the formation of ZnS layer on the ZnO nanostructures, which is not possible for either of the material individually. The cyclic voltammetry results indicates the enhancement in photocurrent density after illumination for the synthesized nanostructures. The electrocatalytic behaviour of ZnO@ZnS electrodes have been studied using a 3-electrode system in presence of 0.1M NaOH electrolyte solution with respect to an Ag/AgCl reference electrode.

  6. Three-Dimensional ZnO Hierarchical Nanostructures: Solution Phase Synthesis and Applications

    PubMed Central

    Wang, Xiaoliang; Ahmad, Mashkoor

    2017-01-01

    Zinc oxide (ZnO) nanostructures have been studied extensively in the past 20 years due to their novel electronic, photonic, mechanical and electrochemical properties. Recently, more attention has been paid to assemble nanoscale building blocks into three-dimensional (3D) complex hierarchical structures, which not only inherit the excellent properties of the single building blocks but also provide potential applications in the bottom-up fabrication of functional devices. This review article focuses on 3D ZnO hierarchical nanostructures, and summarizes major advances in the solution phase synthesis, applications in environment, and electrical/electrochemical devices. We present the principles and growth mechanisms of ZnO nanostructures via different solution methods, with an emphasis on rational control of the morphology and assembly. We then discuss the applications of 3D ZnO hierarchical nanostructures in photocatalysis, field emission, electrochemical sensor, and lithium ion batteries. Throughout the discussion, the relationship between the device performance and the microstructures of 3D ZnO hierarchical nanostructures will be highlighted. This review concludes with a personal perspective on the current challenges and future research. PMID:29137195

  7. Growth of hybrid carbon nanostructures on iron-decorated ZnO nanorods

    NASA Astrophysics Data System (ADS)

    Mbuyisa, Puleng N.; Rigoni, Federica; Sangaletti, Luigi; Ponzoni, Stefano; Pagliara, Stefania; Goldoni, Andrea; Ndwandwe, Muzi; Cepek, Cinzia

    2016-04-01

    A novel carbon-based nanostructured material, which includes carbon nanotubes (CNTs), porous carbon, nanostructured ZnO and Fe nanoparticles, has been synthetized using catalytic chemical vapour deposition (CVD) of acetylene on vertically aligned ZnO nanorods (NRs). The deposition of Fe before the CVD process induces the presence of dense CNTs in addition to the variety of nanostructures already observed on the process done on the bare NRs, which range from amorphous graphitic carbon up to nanostructured dendritic carbon films, where the NRs are partially or completely etched. The combination of scanning electron microscopy and in situ photoemission spectroscopy indicate that Fe enhances the ZnO etching, and that the CNT synthesis is favoured by the reduced Fe mobility due to the strong interaction between Fe and the NRs, and to the presence of many defects, formed during the CVD process. Our results demonstrate that the resulting new hybrid shows a higher sensitivity to ammonia gas at ambient conditions (∼60 ppb) than the carbon nanostructures obtained without the aid of Fe, the bare ZnO NRs, or other one-dimensional carbon nanostructures, making this system of potential interest for environmental ammonia monitoring. Finally, in view of the possible application in nanoscale optoelectronics, the photoexcited carrier behaviour in these hybrid systems has been characterized by time-resolved reflectivity measurements.

  8. Probing defects in ZnO nanostructures by Photoluminescence and Positron Annihilation Spectroscopy

    NASA Astrophysics Data System (ADS)

    Ghosh, Manoranjan; Raychaudhuri, A. K.; Chaudhuri, S. K.; Das, Dipankar

    2008-03-01

    We have investigated defect related emission in the blue green region (2.2 eV -- 2.5 eV) of ZnO nanostructures having spherical (5 nm-15 nm) as well as those with hexagonal platelet and rod like morphologies (20nm-100 nm), synthesized by solvo-thermal route. This emission show anomalous size dependence. Emission energy near 2.2 eV, shifts to higher energy (2.5 eV) for increase in size beyond 20nm when shape of the nanostructures changes. This change in photoluminescence has a close correlation with the size (and shape) induced change in the positron trapping rate which is directly proportional to the defect concentration. The trapping rates show non-monotonous dependence on size. It increases initially as the size increases (5nm-15nm) and then decreases as the size increases beyond 20nm. While increase of the trapping rate on size reduction is expected due to accumulation of more defects at the surface, the initial dependence of the trapping rate on the size (below 20nm) is anomalous. The data are explained by the presence of defects like Zn vacancy and confinement due to size reduction.

  9. Effects of optical band gap energy, band tail energy and particle shape on photocatalytic activities of different ZnO nanostructures prepared by a hydrothermal method

    NASA Astrophysics Data System (ADS)

    Klubnuan, Sarunya; Suwanboon, Sumetha; Amornpitoksuk, Pongsaton

    2016-03-01

    The dependence of the crystallite size and the band tail energy on the optical properties, particle shape and oxygen vacancy of different ZnO nanostructures to catalyse photocatalytic degradation was investigated. The ZnO nanoplatelets and mesh-like ZnO lamellae were synthesized from the PEO19-b-PPO3 modified zinc acetate dihydrate using aqueous KOH and CO(NH2)2 solutions, respectively via a hydrothermal method. The band tail energy of the ZnO nanostructures had more influence on the band gap energy than the crystallite size. The photocatalytic degradation of methylene blue increased as a function of the irradiation time, the amount of oxygen vacancy and the intensity of the (0 0 0 2) plane. The ZnO nanoplatelets exhibited a better photocatalytic degradation of methylene blue than the mesh-like ZnO lamellae due to the migration of the photoelectrons and holes to the (0 0 0 1) and (0 0 0 -1) planes, respectively under the internal electric field, that resulted in the enhancement of the photocatalytic activities.

  10. Electrical and structural properties of ZnO synthesized via infiltration of lithographically defined polymer templates

    SciTech Connect

    Nam, Chang-Yong, E-mail: cynam@bnl.gov; Stein, Aaron; Kisslinger, Kim

    We investigate the electrical and structural properties of infiltration-synthesized ZnO. In-plane ZnO nanowire arrays with prescribed positional registrations are generated by infiltrating diethlyzinc and water vapor into lithographically defined SU-8 polymer templates and removing organic matrix by oxygen plasma ashing. Transmission electron microscopy reveals that homogeneously amorphous as-infiltrated polymer templates transform into highly nanocrystalline ZnO upon removal of organic matrix. Field-effect transistor device measurements show that the synthesized ZnO after thermal annealing displays a typical n-type behavior, ∼10{sup 19 }cm{sup −3} carrier density, and ∼0.1 cm{sup 2} V{sup −1} s{sup −1} electron mobility, reflecting highly nanocrystalline internal structure. The results demonstrate themore » potential application of infiltration synthesis in fabricating metal oxide electronic devices.« less

  11. Electrical and structural properties of ZnO synthesized via infiltration of lithographically defined polymer templates

    SciTech Connect

    Chang-Yong Nam; Stein, Aaron; Kisslinger, Kim

    We investigate the electrical and structural properties of infiltration-synthesized ZnO. In-plane ZnO nanowire arrays with prescribed positional registrations are generated by infiltrating diethlyzinc and water vapor into lithographically defined SU-8 polymer templates and removing organic matrix by oxygen plasma ashing. Transmission electron microscopy reveals that homogeneously amorphous as-infiltrated polymer templates transform into highly nanocrystalline ZnO upon removal of organic matrix. Field-effect transistor device measurements show that the synthesized ZnO after thermal annealing displays a typical n-type behavior, ~1019 cm -3 carrier density, and ~0.1 cm 2 V -1 s -1 electron mobility, reflecting highly nanocrystalline internal structure. The results demonstratemore » the potential application of infiltration synthesis in fabricating metal oxide electronic devices.« less

  12. Electrical and structural properties of ZnO synthesized via infiltration of lithographically defined polymer templates

    DOE PAGES

    Chang-Yong Nam; Stein, Aaron; Kisslinger, Kim; ...

    2015-11-17

    We investigate the electrical and structural properties of infiltration-synthesized ZnO. In-plane ZnO nanowire arrays with prescribed positional registrations are generated by infiltrating diethlyzinc and water vapor into lithographically defined SU-8 polymer templates and removing organic matrix by oxygen plasma ashing. Transmission electron microscopy reveals that homogeneously amorphous as-infiltrated polymer templates transform into highly nanocrystalline ZnO upon removal of organic matrix. Field-effect transistor device measurements show that the synthesized ZnO after thermal annealing displays a typical n-type behavior, ~1019 cm -3 carrier density, and ~0.1 cm 2 V -1 s -1 electron mobility, reflecting highly nanocrystalline internal structure. The results demonstratemore » the potential application of infiltration synthesis in fabricating metal oxide electronic devices.« less

  13. Precursor-controlled synthesis of hierarchical ZnO nanostructures, using oligoaniline-coated Au nanoparticle seeds

    NASA Astrophysics Data System (ADS)

    Krishnan, Deepti; Pradeep, T.

    2009-07-01

    Shape-selected synthesis of a large number of zinc oxide (ZnO) nano- and microstructures was achieved by the seed-mediated growth of oligoaniline-coated gold nanoparticle precursors. Distinctive ZnO structures such as nanoplates, nanospheres, microstars, microflowers, microthorns and micromultipods were synthesized by this method. Slightly different shapes were obtained in the absence of the seed solution. This is a fast, low temperature (60 °C) and biomimetic route to make a wide variety of structures. The structure and morphology of the nanostructures were studied by transmission electron microscopy (TEM) and scanning electron microscopy (SEM), respectively. Raman spectroscopy, Fourier-transform infrared (FTIR) spectroscopy and X-ray diffraction (XRD) were utilized for the characterization of the nanostructures. A growth mechanism for these nanostructures was proposed based on these results. The concentrations of the reacting species were the main parameter causing the changes in the morphologies. The variation in morphologies of these structures is believed to be due to the ability of the seed solution as well as polyvinylpyrrolidone (PVP) to selectively suppress/depress the growth of certain planes, allowing growth to occur only in certain specific directions. Changes in the amount of growth nuclei with varying sodium hydroxide (NaOH) concentration is also seen to affect the morphology of these structures.

  14. The effect of induced strains on photoluminescence properties of ZnO nanostructures grown by thermal evaporation method

    NASA Astrophysics Data System (ADS)

    Arjmand, Yaser; Eshghi, Hosein

    2016-03-01

    In this paper, ZnO nanostructures have been synthesized by thermal evaporation process using metallic zinc powder in the presence of oxygen on p-Si (100) at different distances from the boat. The structural and optical characterizations have been carried out. The morphological study shows various shape nanostructures. XRD data indicate that all samples have a polycrystalline wurtzite hexagonal structure in such a way that the closer sample has a preferred orientation along (101) while the ones farther are grown along (002) direction. From the structural and optical data analysis, we found that the induced strains are the main parameter controlling the UV/green peaks ratios in the PL spectra of the studied samples.

  15. Removal of Micrometer Size Morphological Defects and Enhancement of Ultraviolet Emission by Thermal Treatment of Ga-Doped ZnO Nanostructures

    PubMed Central

    Manzoor, Umair; Kim, Do K.; Islam, Mohammad; Bhatti, Arshad S.

    2014-01-01

    Mixed morphologies of Ga-doped Zinc Oxide (ZnO) nanostructures are synthesized by vapor transport method. Systematic scanning electron microscope (SEM) studies of different morphologies, after periodic heat treatments, gives direct evidence of sublimation. SEM micrographs give direct evidence that morphological defects of nanostructures can be removed by annealing. Ultra Violet (UV) and visible emission depends strongly on the annealing temperatures and luminescent efficiency of UV emission is enhanced significantly with each subsequent heat treatment. X-Ray diffraction (XRD) results suggest that crystal quality improved by annealing and phase separation may occur at high temperatures. PMID:24489725

  16. Removal of micrometer size morphological defects and enhancement of ultraviolet emission by thermal treatment of Ga-doped ZnO nanostructures.

    PubMed

    Manzoor, Umair; Kim, Do K; Islam, Mohammad; Bhatti, Arshad S

    2014-01-01

    Mixed morphologies of Ga-doped Zinc Oxide (ZnO) nanostructures are synthesized by vapor transport method. Systematic scanning electron microscope (SEM) studies of different morphologies, after periodic heat treatments, gives direct evidence of sublimation. SEM micrographs give direct evidence that morphological defects of nanostructures can be removed by annealing. Ultra Violet (UV) and visible emission depends strongly on the annealing temperatures and luminescent efficiency of UV emission is enhanced significantly with each subsequent heat treatment. X-Ray diffraction (XRD) results suggest that crystal quality improved by annealing and phase separation may occur at high temperatures.

  17. Structural studies of ZnO nanostructures by varying the deposition parameters

    NASA Astrophysics Data System (ADS)

    Yunus, S. H. A.; Sahdan, M. Z.; Ichimura, M.; Supee, A.; Rahim, S.

    2017-01-01

    The effect of Zinc Oxide (ZnO) thin film on the growth of ZnO nanorods (NRs) was investigated. The structures of ZnO NRs were synthesized by chemical bath deposition (CBD) method in aqueous solution of N2O6Zn.6H2O and C6H12N4 at 90°C of deposition temperature. One of the ZnO NRs samples was deposited on a ZnO seed layer coated on a glass substrate to investigate the properties of ZnO NRs without receiving effect of other materials. Next, for diode application, the ZnO NRs was deposited on tin monosulfide (SnS) coated on indium-tin-oxide (ITO) coated glass substrate (SnS/ITO). The next, the ZnO structural properties were studied from surface morphology, X-ray diffractometer (XRD) spectra, and chemical composition by using field emission scanning electron microscope (FESEM), XRD and energy dispersive X-ray Spectroscopy (EDX). The growth of ZnO NRs on ZnO seed layer was investigated by ZnO seed layer condition while the growth of ZnO NRs on SnS/ITO was investigated by deposition time and deposition temperature parameters. From FESEM images, aligned ZnO NRs were obtained, and the diameters of ZnO NRs were 0.024-3.94 µm. The SnS thin film was affected by the diameter of ZnO NRs which are the ZnO NRs grow on SnS thin films has a larger diameter compared to ZnO NRs grow on ZnO seed layer. Besides that, all of ZnO peaks observed from XRD corresponding to the wurzite structure and preferentially oriented along the c-axis. In addition, EDX shows a high composition of zinc (Zn) and oxygen (O) signals, which indicated that the NRs are indeed made up of Zn and O.

  18. On-chip surface modified nanostructured ZnO as functional pH sensors

    NASA Astrophysics Data System (ADS)

    Zhang, Qing; Liu, Wenpeng; Sun, Chongling; Zhang, Hao; Pang, Wei; Zhang, Daihua; Duan, Xuexin

    2015-09-01

    Zinc oxide (ZnO) nanostructures are promising candidates as electronic components for biological and chemical applications. In this study, ZnO ultra-fine nanowire (NW) and nanoflake (NF) hybrid structures have been prepared by Au-assisted chemical vapor deposition (CVD) under ambient pressure. Their surface morphology, lattice structures, and crystal orientation were investigated by scanning electron microscopy (SEM), x-ray diffraction (XRD), and transmission electron microscopy (TEM). Two types of ZnO nanostructures were successfully integrated as gate electrodes in extended-gate field-effect transistors (EGFETs). Due to the amphoteric properties of ZnO, such devices function as pH sensors. We found that the ultra-fine NWs, which were more than 50 μm in length and less than 100 nm in diameter, performed better in the pH sensing process than NW-NF hybrid structures because of their higher surface-to-volume ratio, considering the Nernst equation and the Gouy-Chapman-Stern model. Furthermore, the surface coating of (3-Aminopropyl)triethoxysilane (APTES) protects ZnO nanostructures in both acidic and alkaline environments, thus enhancing the device stability and extending its pH sensing dynamic range.

  19. Inhibition of growth of S. epidermidis by hydrothermally synthesized ZnO nanoplates

    NASA Astrophysics Data System (ADS)

    Abinaya, C.; Mayandi, J.; Osborne, J.; Frost, M.; Ekstrum, C.; Pearce, J. M.

    2017-07-01

    The antibacterial effect of zinc oxide (ZnO#1) as prepared and annealed (ZnO#2) at 400 °C, Cu doped ZnO (CuZnO), and Ag doped ZnO (AgZnO) nanoplates on Staphylococcus epidermidis was investigated for the inhibition and inactivation of cell growth. The results shows that pure ZnO and doped ZnO samples exhibited antibacterial activity against Staphylococcus epidermidis (S. epidermidis) as compared to tryptic soy broth (TSB). Also it is observed that S. epidermidis was extremely sensitive to treatment with ZnO nanoplates and it is clear that the effect is not purely depend on Cu/Ag. Phase identification of a crystalline material and unit cell dimensions were studied by x-ray powder diffraction (XRD). The scanning electron microscopy (SEM) provides information on sample’s surface topography and the EDX confirms the presence of Zn, O, Cu and Ag. X-ray photo-electron spectroscopy (XPS) was used to analyze the elemental composition and electronic state of the elements that exist within the samples. These studies confirms the formation of nanoplates and the presence of Zn, O, Ag, Cu with the oxidation states  +2, -2, 0 and  +2 respectively. These results indicates promising antibacterial applications of these ZnO-based nanoparticles synthesized with low-cost hydrothermal methods.

  20. Nanostructured zinc oxide films synthesized by successive chemical solution deposition for gas sensor applications

    SciTech Connect

    Lupan, O.; Department of Physics, University of Central Florida, 4000 Central Florida Blvd., Orlando, FL 32816-2385; Chow, L.

    2009-01-08

    Nanostructured ZnO thin films have been deposited using a successive chemical solution deposition method. The structural, morphological, electrical and sensing properties of the films were studied for different concentrations of Al-dopant and were analyzed as a function of rapid photothermal processing temperatures. The films were investigated by X-ray diffraction, scanning electron microscopy, energy dispersive X-ray spectroscopy, X-ray photoelectron and micro-Raman spectroscopy. Electrical and gas sensitivity measurements were conducted as well. The average grain size is 240 and 224 A for undoped ZnO and Al-doped ZnO films, respectively. We demonstrate that rapid photothermal processing is an efficient method for improving themore » quality of nanostructured ZnO films. Nanostructured ZnO films doped with Al showed a higher sensitivity to carbon dioxide than undoped ZnO films. The correlations between material compositions, microstructures of the films and the properties of the gas sensors are discussed.« less

  1. Luminescence studies of laser MBE grown GaN on ZnO nanostructures

    NASA Astrophysics Data System (ADS)

    Dewan, Sheetal; Tomar, Monika; Kapoor, Ashok K.; Tandon, R. P.; Gupta, Vinay

    2017-08-01

    GaN films have been successfully fabricated using Laser Molecular Beam Epitaxy (LMBE) technique on bare c-plane sapphire substrate and ZnO nanostructures (NS) decorated Si (100) substrates. The ZnO nanostructures were grown on Si (100) substrate using high pressure assisted Pulsed laser deposition technique in inert gas ambience. Discrete nanostructured morphology of ZnO was obtained using the PLD growth on Si substrates. Photoluminescence studies performed on the prepared GaN/Sapphire and GaN/ZnO-NS/Si systems, revealed a significant PL enhancement in case of GaN/ZnO-NS/Si system compared to the former. The hexagonal nucleation sites provided by the ZnO nanostructures strategically enhanced the emission of GaN film grown by Laser MBE Technique at relatively lower temperature of 700°C. The obtained results are attractive for the realization of highly luminescent GaN films on Si substrate for photonic devices.

  2. Enhanced photocatalytic performance of ZnO nanostructures by electrochemical hybridization with graphene oxide

    NASA Astrophysics Data System (ADS)

    Pruna, A.; Wu, Z.; Zapien, J. A.; Li, Y. Y.; Ruotolo, A.

    2018-05-01

    Synthesis of zinc oxide (ZnO) nanostructures is reported by electrochemical deposition from an aqueous electrolyte in presence of graphene oxide (GO) with varying oxidation degree. The properties of hybrids were investigated by scanning electron microscopy, X-ray diffraction, Raman, Fourier-Transform Infrared and X-ray photoelectron spectroscopy techniques and photocatalytic measurements. The results indicated the electrodeposition of ZnO in presence of GO with increased oxygen content led to marked differences in the morphology while Raman measurements indicated an increased defect level both in the ZnO and the electrochemically reduced GO (ErGO) within the hybrids. The decrease in C/O atomic ratio of GO (from 0.79 to 0.71) employed for the electrodeposition of ZnO resulted in an increase in photocatalytic efficiency for methylene blue degradation under UV irradiation from 4-folds to 10-folds with respect to non-hybridized ZnO. The observed synergetic effect of cathodic deposition potential and oxygen content in GO towards improving the photocatalytic activity of immobilized ZnO is expected to contribute to further development of more effective deposition approaches for the preparation of high performance hybrid nanostructures.

  3. Structural and optical properties of ZnO nanorods synthesized via template free approach

    NASA Astrophysics Data System (ADS)

    Kajal, Priyanka; D, Pooja; Jaggi, Neena

    2016-06-01

    In this paper, we report a novel method for synthesis of semiconducting ZnO nanorods using Zinc acetate dehydrate precursor in a methanol—de-ionized (1:5) mixture via template free approach. Scanning electron microscope (SEM) and transmission electron microscope (TEM) images of as synthesized nanorods revealed hexagonal symmetry of rods, whereas x-ray diffraction (XRD) analysis for structure and phase has shown high crystallinity with wurtzite crystal structure. The structural characterization by FT-IR analysis revealed presence of various groups on as synthesized ZnO nanorods, whereas the UV-Vis analysis has shown a blue shift in the absorption spectra as compared to bulk ZnO due to quantum confinement of charge carriers. Photoluminescence (PL) spectroscopy study has also been performed revealing a good degree of phosphorescence in the ZnO nanorods. Further, thermo gravimetric analysis (TGA) revealed that as synthesized nanorods by present method are highly stable at high temperature (1000 °C). This study provides an alternative, less expensive and a very simple method for the fabrication of ZnO nanorods in abundance, which can be further used for various sensing applications, in particular, gas sensing.

  4. Incorporation of ZnO and their composite nanostructured material into a cotton fabric platform for wearable device applications.

    PubMed

    Veluswamy, Pandiyarasan; Sathiyamoorthy, Suhasini; Khan, Faizan; Ghosh, Aranya; Abhijit, Majumdar; Hayakawa, Yasuhiro; Ikeda, Hiroya

    2017-02-10

    The central idea of this paper is to innovate a new approach for the development of wearable device materials through the coating of cotton fabric with ZnO and Sb-/Ag-/ZnO composites. The study was designed in order to have a clear understanding of the role of ZnO as well as the modified composite thereof under investigation. Cotton fabric with uniform ZnO/ZnO-composite layers on the surface was successfully synthesized via a solvothermal method. The growth behaviors were investigated by comparing ZnO and ZnO-composites. The structural, morphological, chemical states, optical, electrical and thermopower properties of these fabrics were studied. Nanostructured ZnO-composite fabric had enhanced UV shielding with a value of 83.96. It is found that the ZnO-composite fabrics have increased electrical conductivity. The thermopower value of the ZnO-composite fabric could reach 471.9μVK -1 . Such materials are anticipated to be worthwhile as wearable electronic devices and as protective textiles. Copyright © 2016 Elsevier Ltd. All rights reserved.

  5. Microwave Synthesized ZnO Nanorod Arrays for UV Sensors: A Seed Layer Annealing Temperature Study.

    PubMed

    Pimentel, Ana; Ferreira, Sofia Henriques; Nunes, Daniela; Calmeiro, Tomas; Martins, Rodrigo; Fortunato, Elvira

    2016-04-20

    The present work reports the influence of zinc oxide (ZnO) seed layer annealing temperature on structural, optical and electrical properties of ZnO nanorod arrays, synthesized by hydrothermal method assisted by microwave radiation, to be used as UV sensors. The ZnO seed layer was produced using the spin-coating method and several annealing temperatures, ranging from 100 to 500 °C, have been tested. X-ray diffraction (XRD), scanning electron microscopy (SEM), atomic force microscopy (AFM) and spectrophotometry measurements have been used to investigate the structure, morphology, and optical properties variations of the produced ZnO nanorod arrays regarding the seed layer annealing temperatures employed. After the growth of ZnO nanorod arrays, the whole structure was tested as UV sensors, showing an increase in the sensitivity with the increase of seed layer annealing temperature. The UV sensor response of ZnO nanorod arrays produced with the seed layer annealed temperature of 500 °C was 50 times superior to the ones produced with a seed layer annealed at 100 °C.

  6. Investigations on photoelectrochemical performance of boron doped ZnO nanorods synthesized by facile hydrothermal technique

    NASA Astrophysics Data System (ADS)

    Sharma, Akash; Chakraborty, Mohua; Thangavel, R.

    2018-05-01

    Undoped and 10% Boron (B)-doped Zinc Oxide nanorods (ZnO NRs) on Tin doped Indium Oxide (ITO) coated glass substrates were synthesized using facile sol-gel, spin coating and hydrothermal method. The impact of adding Boron on the structural, optical properties, surface morphology and photoelectrochemical (PEC) performances of the ZnO NRs have been investigated. The XRD pattern confirmed the formation of pure hexagonal phase with space group P63mc (186). The same can also be clearly observed form the FESEM images. The UV-Vis study shows the narrowing in band gap from 3.22 eV to 3.19 eV with incorporation of Boron in ZnO matrix. The B-doped ZnO NRs sample shows an enhanced photocurrent density of 1.31 mA/cm2 at 0.5 V (vs. Ag/AgCl), which is more than 171% enhancement compared to bare ZnO NRs (0.483 mA/cm2) in 0.1 M Na2SO4 aqueous solution. The results clearly indicates that the boron doped ZnO NRs can be used as an efficient photoelectrode material for photoelectrochemical cell.

  7. Sol-gel synthesized ZnO for optoelectronics applications: a characterization review

    NASA Astrophysics Data System (ADS)

    Harun, Kausar; Hussain, Fayaz; Purwanto, Agus; Sahraoui, Bouchta; Zawadzka, Anna; Azmin Mohamad, Ahmad

    2017-12-01

    The rapid growth in green technology has resulted in a marked increase in the incorporation of ZnO in energy and optoelectronic devices. Research involving ZnO is being given renewed attention in the quest to fully exploit its promising properties. The purity and state of defects in the ZnO system are optimized through several modifications to the synthesis conditions and the starting materials. These works have been verified through a series of characterizations. This review covers the essential characterization outcomes of pure ZnO nanoparticles. Emphasis is placed on recent techniques, examples and some issues concerning sol-gel synthesized ZnO nanoparticles. Thermal, phase, structural and morphological observations are combined to ascertain the level of purity of ZnO. The subsequent elemental and optical characterizations are also discussed. This review would be the collective information and suggestions at one place for investigators to focus on the best development of ZnO-based optical and energy devices.

  8. Microwave Synthesized ZnO Nanorod Arrays for UV Sensors: A Seed Layer Annealing Temperature Study

    PubMed Central

    Pimentel, Ana; Ferreira, Sofia Henriques; Nunes, Daniela; Calmeiro, Tomas; Martins, Rodrigo; Fortunato, Elvira

    2016-01-01

    The present work reports the influence of zinc oxide (ZnO) seed layer annealing temperature on structural, optical and electrical properties of ZnO nanorod arrays, synthesized by hydrothermal method assisted by microwave radiation, to be used as UV sensors. The ZnO seed layer was produced using the spin-coating method and several annealing temperatures, ranging from 100 to 500 °C, have been tested. X-ray diffraction (XRD), scanning electron microscopy (SEM), atomic force microscopy (AFM) and spectrophotometry measurements have been used to investigate the structure, morphology, and optical properties variations of the produced ZnO nanorod arrays regarding the seed layer annealing temperatures employed. After the growth of ZnO nanorod arrays, the whole structure was tested as UV sensors, showing an increase in the sensitivity with the increase of seed layer annealing temperature. The UV sensor response of ZnO nanorod arrays produced with the seed layer annealed temperature of 500 °C was 50 times superior to the ones produced with a seed layer annealed at 100 °C. PMID:28773423

  9. Study of Doped ZnO Films Synthesized by Combining Vapor Gases and Pulsed Laser Deposition

    NASA Technical Reports Server (NTRS)

    Zhu, Shen; Su, Ching-Hua; Lehoczky, Sandor L.; George, M. A.

    2000-01-01

    The properties and structure of the ZnO material are similar to those of the GaN. Since an excitonic binding energy of ZnO is about 60 meV, it has strong potential for excitonic lasing at the room temperature. This makes synthesizing ZnO films for applications attractive. However, there are several hurdles in fabricating electro-optical devices from ZnO. One of those is in growing doped p-type ZnO films. Although techniques have been developed for the doping of both p-type and n-type ZnO, this remains an area that can be improved. In this presentation, we will report the experimental results of using both thermal vapor and pulsed laser deposition to grow doped ZnO films. The films are deposited on (0001) sapphire, (001) Si and quartz substrates by ablating a ZnO target. The group III and V elements are introduced into the growth chamber using inner gases. Films are characterized by x-ray diffraction, scanning probe microscopy, energy dispersive spectroscopy, Auger electron spectroscopy, and electrical measurements. The full width at half maximum of theta rocking curves for epitaxial films is less than 0.5 deg. In textured films, it rises to several degrees. Film surface morphology reveals an island growth pattern, but the size and density of these islands vary with the composition of the reactive gases. The electrical resistivity also changes with the doped elements. The relationship between the doping elements, gas composition, and film properties will be discussed.

  10. Electrochemical synthesis of one-dimensional ZnO nanostructures on ZnO seed layer for DSSC applications

    NASA Astrophysics Data System (ADS)

    Marimuthu, T.; Anandhan, N.; Thangamuthu, R.

    2018-01-01

    Electrochemical deposition of vertically aligned zinc oxide (ZnO) nanorods were prepared on ZnO seeded fluorine doped tin oxide (FTO) substrate in the solutions consisting of different concentrations of hexamethylenetetramine (HMTA). The electrochemical, structural, morphological, vibrational and optical properties were characterized by cyclic voltammetry (CV), X-ray diffraction (XRD), scanning electron microscope (SEM), Raman spectroscopy and photoluminescence (PL) spectroscopy, respectively. CV curves confirm that metallic zinc phase is not deposited as the HMTA concentration is about 9 mM in a deposition solution. XRD patterns of the as-prepared films show that the increasing HMTA concentrations from 0 mM to 9 mM not only increase the formation of zinc hydrate chloride (Zn5(OH)8Cl2·H2O) but also decrease and finally disappear the metallic Zn deposition. After the as-prepared films annealed at 450 ° C, the crystalline phases of Zn and Zn5(OH)8Cl2·H2O are completely converted to ZnO hexagonal wurtzite phase with high intense growth (002) plane orientation. SEM images support that the vertical growth of ZnO nanostructures (nanorods and petals) with a few flowers is found to be in the cordillera structure as the films are deposited in the solutions consisting of 3 mM, 6 mM and 9 mM HMTA respectively. Raman and PL spectra confirm that the ZnO film deposited in the solution consisting of 9 mM HMTA has a higher crystalline nature with lesser atomic defects and is also higher c-axis growth than that of other films deposited in the solutions consisting of 0 mM, 3 mM and 6 mM, respectively. UV-vis absorbance spectra corroborate that the ZnO film deposited in the solution consisting of 9 mM HMTA shows a high dye absorbance as compared with other films. The efficiency of DSSCs based on ZnO photoanodes deposited in the solutions consisting of 0 mM and 9 mM HMTA was 1.79 and 3.75%, respectively. Electrochemical impedance spectra revealed that DSSC based on ZnO photoanode

  11. Photocatalytic properties of hierarchical ZnO flowers synthesized by a sucrose-assisted hydrothermal method

    NASA Astrophysics Data System (ADS)

    Lv, Wei; Wei, Bo; Xu, Lingling; Zhao, Yan; Gao, Hong; Liu, Jia

    2012-10-01

    In this work, hierarchical ZnO flowers were synthesized via a sucrose-assisted urea hydrothermal method. The thermogravimetric analysis/differential thermal analysis (TGA-DTA) and Fourier transform infrared spectra (FTIR) showed that sucrose acted as a complexing agent in the synthesis process and assisted combustion during annealing. Photocatalytic activity was evaluated using the degradation of organic dye methyl orange. The sucrose added ZnO flowers showed improved activity, which was mainly attributed to the better crystallinity as confirmed by X-ray photoelectron spectroscopy (XPS) analysis. The effect of sucrose amount on photocatalytic activity was also studied.

  12. ZnO nanostructures with different morphology for enhanced photocatalytic activity

    NASA Astrophysics Data System (ADS)

    Peter, I. John; Praveen, E.; Vignesh, G.; Nithiananthi, P.

    2017-12-01

    ZnO nanomaterials of different morphologies have been synthesized and the effect of morphology on Photocatalytic activity on natural dye has been investigated. Crystalline size and lattice strain of the synthesized particles are determined by XRD analysis and Williamson-Hall (W-H) method respectively. All other important physical parameters such as strain, stress and energy density values are also calculated using W-H analysis using different models such as uniform deformation model, uniform deformation stress model and uniform deformation energy density model. A shift in the peak of FTIR spectrum of ZnO is observed due to morphology effects. The SEM analysis reveals that the synthesized ZnO nanoparticles appear as flake, rod and dot. ZnO quantum dot exhibits higher photocatalytic activity comparing to the other morphologies. Larger surface area, high adsorption rate, large charge separation and the slow recombination of electrons/holes in ZnO dots establish dots as favorable morphology for good photocatalysis. Among the three, ZnO quantum dot shows three-times enhancement in the kinetic rate constants of photocatalysis. The results confirm that availability of specific (active) surface area, photocatalytic potential and quantum confinement of photo-induced carriers differ with morphology.

  13. Simple chemical synthesis of novel ZnO nanostructures: Role of counter ions

    NASA Astrophysics Data System (ADS)

    Pudukudy, Manoj; Yaakob, Zahira

    2014-04-01

    This article reports the synthesis, characterisation and photocatalytic activity of novel ZnO nanostructures prepared via the thermal decomposition of hydrozincite. Hydrozincites were obtained by the conventional precipitation route using different zinc salts such as acetate, nitrate, chloride and sulphate. The effect of counter ions (CH3COO-, Cl-, NO3-, and SO42-) on the structural, textural, morphological and optical properties was investigated. Various characterisations depicted the active role of counter ions in the properties of ZnO. Hexagonal wurtzite structure of ZnO with fine crystalline size was obvious from the XRD results, irrespective of the counter ions. Electron microscopic images indicated the role of counter ions in the surface and internal morphology of ZnO nanomaterials. Special coral like agglomerated morphology of elongated particles with high porosity was observed for the ZnO prepared from acetate precursor. Spherical, elongated and irregular shaped bigger lumps of ZnO nanoparticles with various novel morphologies were resulted for the sulphate, nitrate and chloride precursors respectively. Highly ordered porous micro disc like morphology was noted for the ZnO samples prepared from the sulphate and nitrate salts. Photoluminescence spectra showed the characteristic blue and green emission bands, depicting the presence of large crystal defects and high oxygen vacancies in the samples. Photocatalytic activity of the as-prepared ZnO catalysts was examined by the degradation of methylene blue under UV light irradiation. Degradation results indicated their substantial activity with respect to the counter ions. ZnO prepared from the acetate precursor showed highest photoactivity due to its high surface area, special morphology and high oxygen vacancies.

  14. Superhydrophobic Ag decorated ZnO nanostructured thin film as effective surface enhanced Raman scattering substrates

    NASA Astrophysics Data System (ADS)

    Jayram, Naidu Dhanpal; Sonia, S.; Poongodi, S.; Kumar, P. Suresh; Masuda, Yoshitake; Mangalaraj, D.; Ponpandian, N.; Viswanathan, C.

    2015-11-01

    The present work is an attempt to overcome the challenges in the fabrication of super hydrophobic silver decorated zinc oxide (ZnO) nanostructure thin films via thermal evaporation process. The ZnO nanowire thin films are prepared without any surface modification and show super hydrophobic nature with a contact angle of 163°. Silver is further deposited onto the ZnO nanowire to obtain nanoworm morphology. Silver decorated ZnO (Ag@ZnO) thin films are used as substrates for surface enhanced Raman spectroscopy (SERS) studies. The formation of randomly arranged nanowire and silver decorated nanoworm structure is confirmed using FESEM, HR-TEM and AFM analysis. Crystallinity and existence of Ag on ZnO are confirmed using XRD and XPS studies. A detailed growth mechanism is discussed for the formation of the nanowires from nanobeads based on various deposition times. The prepared SERS substrate reveals a reproducible enhancement of 3.082 × 107 M for Rhodamine 6G dye (R6G) for 10-10 molar concentration per liter. A higher order of SERS spectra is obtained for a contact angle of 155°. Thus the obtained thin films show the superhydrophobic nature with a highly enhanced Raman spectrum and act as SERS substrates. The present nanoworm morphology shows a new pathway for the construction of semiconductor thin films for plasmonic studies and challenges the orderly arranged ZnO nanorods, wires and other nano structure substrates used in SERS studies.

  15. Composite multifunctional nanostructures based on ZnO tetrapods and superparamagnetic Fe3O4 nanoparticles.

    PubMed

    Villani, M; Rimoldi, T; Calestani, D; Lazzarini, L; Chiesi, V; Casoli, F; Albertini, F; Zappettini, A

    2013-04-05

    A nanocomposite material is obtained by coupling superparamagnetic magnetite nanoparticles (Fe3O4 NP) and vapor phase grown zinc oxide nanostructures with 'tetrapod' morphology (ZnO TP). The aim is the creation of a multifunctional material which retains the attractive features of ZnO (e.g. surface reactivity, strong UV emission, piezoelectricity) together with added magnetism. Structural, morphological, optical, magnetic and functional characterization are performed. In particular, the high saturation magnetization of Fe3O4 NP (above 50 A m(2) kg(-1)), the strong UV luminescence and the enhanced photocatalytic activity of coupled nanostructures are discussed. Thus the nanocomposite turns out to be suitable for applications in energy harvesting and conversion, gas- and bio-sensing, bio-medicine and filter-free photocatalysis.

  16. Detectors based on Pd-doped and PdO-functionalized ZnO nanostructures

    NASA Astrophysics Data System (ADS)

    Postica, V.; Lupan, O.; Ababii, N.; Hoppe, M.; Adelung, R.; Chow, L.; Sontea, V.; Aschehoug, P.; Viana, V.; Pauporté, Th.

    2018-02-01

    In this work, zinc oxide (ZnO) nanostructured films were grown using a simple synthesis from chemical solutions (SCS) approach from aqueous baths at relatively low temperatures (< 95 °C). The samples were doped with Pd (0.17 at% Pd) and functionalized with PdO nanoparticles (NPs) using the PdCl2 aqueous solution and subsequent thermal annealing at 650 °C for 30 min. The morphological, micro-Raman and optical properties of Pd modified samples were investigated in detail and were demonstrated to have high crystallinity. Gas sensing studies unveiled that compared to pure ZnO films, the Pd-doped ZnO (ZnO:Pd) nanostructured films showed a decrease in ethanol vapor response and slight increase in H2 response with low selectivity. However, the PdO-functionalized samples showed excellent H2 gas sensing properties with possibility to detect H2 gas even at room temperature (gas response of 2). Up to 200 °C operating temperature the samples are highly selective to H2 gas, with highest response of 12 at 150 °C. This study demonstrates that surface functionalization of n-ZnO nanostructured films with p-type oxides is very important for improvement of gas sensing properties.

  17. Flower-like ZnO nanostructure based electrochemical DNA biosensor for bacterial meningitis detection.

    PubMed

    Tak, Manvi; Gupta, Vinay; Tomar, Monika

    2014-09-15

    Zinc oxide (ZnO) nanostructures possessing flower-like morphology have been synthesised onto platinized silicon substrate by simple and economical hydrothermal method. The interaction of physically immobilized single stranded thiolated DNA (ss th-DNA) probe of N. meningitides onto the nanostructured ZnO (ZNF) matrix surface have been investigated using cyclic voltammetry (CV) and electrochemical impeadance spectroscopy (EIS). The electrochemical sensing response behaviour of the DNA bioelectrode (ss th-DNA/ZNF/Pt/Si) has been studied by both differential pulse voltammetric (DPV) as well as impedimetric techniques. The fabricated DNA biosensor can quantify wide range of the complementary target ss th-DNA in the range 5-240 ng μl(-1) with good linearity (R=0.98), high sensitivity (168.64 μA ng(-1) μl cm(-2)) and low detection limit of about 5 ng μl(-1). Results emphasise that the fabricated flower-like ZnO nanostructures offer a useful platform for the immobilization of DNA molecules and could be exploited for efficient detection of complementary target single stranded DNA corresponding to N. meningitides. Copyright © 2014 Elsevier B.V. All rights reserved.

  18. ZnO Nanostructures for Drug Delivery and Theranostic Applications.

    PubMed

    Martínez-Carmona, Marina; Gun'ko, Yurii; Vallet-Regí, María

    2018-04-23

    In the last two decades, zinc oxide (ZnO) semiconductor Quantum dots (QDs) have been shown to have fantastic luminescent properties, which together with their low-cost, low-toxicity and biocompatibility have turned these nanomaterials into one of the main candidates for bio-imaging. The discovery of other desirable traits such as their ability to produce destructive reactive oxygen species (ROS), high catalytic efficiency, strong adsorption capability and high isoelectric point, also make them promising nanomaterials for therapeutic and diagnostic functions. Herein, we review the recent progress on the use of ZnO based nanoplatforms in drug delivery and theranostic in several diseases such as bacterial infection and cancer.

  19. Nanostructured hybrid ZnO thin films for energy conversion

    PubMed Central

    2011-01-01

    We report on hybrid films based on ZnO/organic dye prepared by electrodeposition using tetrasulfonated copper phthalocyanines (TS-CuPc) and Eosin-Y (EoY). Both the morphology and porosity of hybrid ZnO films are highly dependent on the type of dyes used in the synthesis. High photosensitivity was observed for ZnO/EoY films, while a very weak photoresponse was obtained for ZnO/TS-CuPc films. Despite a higher absorption coefficient of TS-CuPc than EoY, in ZnO/EoY hybrid films, the excited photoelectrons between the EoY levels can be extracted through ZnO, and the porosity of ZnO/EoY can also be controlled. PMID:21711909

  20. ZnO Nanostructures for Drug Delivery and Theranostic Applications

    PubMed Central

    Martínez-Carmona, Marina

    2018-01-01

    In the last two decades, zinc oxide (ZnO) semiconductor Quantum dots (QDs) have been shown to have fantastic luminescent properties, which together with their low-cost, low-toxicity and biocompatibility have turned these nanomaterials into one of the main candidates for bio-imaging. The discovery of other desirable traits such as their ability to produce destructive reactive oxygen species (ROS), high catalytic efficiency, strong adsorption capability and high isoelectric point, also make them promising nanomaterials for therapeutic and diagnostic functions. Herein, we review the recent progress on the use of ZnO based nanoplatforms in drug delivery and theranostic in several diseases such as bacterial infection and cancer. PMID:29690644

  1. Study of Growth Kinetics in One Dimensional and Two Dimensional ZnO Nanostructures

    NASA Astrophysics Data System (ADS)

    Yin, Xin

    Because of the merits arising from the unique geometry, nanostructure materials have been an essential class of materials, which have shown great potentials in the fields of electronics, photonics, and biology. With various nanostructures being intensively investigated and successfully complemented into device applications, there has been one increasing demand to the investigation of the growth mechanism devoted to the controlled nanostructure synthesis. Motivated by this situation, this thesis is focused on the fundamental understanding of the nanostructure growth. Specifically, by taking zinc oxide as an example material, through controlling the basic driving force, that is, the supersaturation, I have rationally designed and synthesized various of nanostructures, and further applied the classical layer-by-layer growth mechanism to the understanding on the formation of these nanostructures, they are, the convex-plate-capped nanowires, the concave-plate-capped nanowires, the facet evolution at the tip of the nanowires, and the ultrathin 2D nanosheets.

  2. Nanostructured TiO2 and ZnO prepared by using pressurized hot water and their eco-toxicological evaluation

    NASA Astrophysics Data System (ADS)

    Troppová, Ivana; Matějová, Lenka; Sezimová, Hana; Matěj, Zdeněk; Peikertová, Pavlína; Lang, Jaroslav

    2017-06-01

    The eco-toxicological effects of unconventionally prepared nanostructured TiO2 and ZnO were evaluated in this study, since both oxides are keenly investigated semiconductor photocatalysts in the last three decades. Unconventional processing by pressurized hot water was applied in order to crystallize oxide materials as an alternative to standard calcination. Acute biological toxicity of the synthesized oxides was evaluated using germination of Sinapis alba seed (ISO 11269-1) and growth of Lemna minor fronds (ISO 20079) and was compared to commercially available TiO2 Degussa P25. Toxicity results revealed that synthesized ZnO as well as TiO2 is toxic contrary to commercial TiO2 Degussa P25 which showled stimulation effect to L. minor and no toxicity to S. alba. ZnO was significantly more toxic than TiO2. The effect of crystallite size was considered, and it was revealed that small crystallite size and large surface area are not the toxicity-determining factors. Factors such as the rate of nanosized crystallites aggregation and concentration, shape and surface properties of TiO2 nanoparticles affect TiO2 toxicity to both plant species. Seriously, the dissolution of Ti4+ ions from TiO2 was also observed which may contribute to its toxicity. In case of ZnO, the dissolution of Zn2+ ions stays the main cause of its toxicity.

  3. Electrical properties of Mg doped ZnO nanostructure annealed at different temperature

    SciTech Connect

    Mohamed, R., E-mail: ruziana12@gmail.com; Mamat, M. H., E-mail: hafiz-030@yahoo.com; Rusop, M., E-mail: nanouitm@gmail.com

    In this work, ZincOxide (ZnO) nanostructures doped with Mg were successfully grown on the glass substrate. Magnesium (Mg) metal element was added in the ZnO host which acts as a doping agent. Different temperature in range of 250°C to 500°C was used in order to investigate the effect of annealing temperature of ZnO thin films. Field Emission Scanning Electron Microscopy (FESEM) was used to investigate the physical characteristic of ZnO thin films. FESEM results have revealed that ZnO nanorods were grown vertically aligned. The structural properties were determined by using X-Ray Diffraction (XRD) analysis. XRD results showed Mg doped ZnOmore » thin have highest crystalinnity at 500°C annealing temperature. The electrical properties were investigating by using Current-Voltage (I-V) measurement. I-V measurement showed the electrical properties were varied at different annealing temperature. The annealing temperature at 500°C has the highest electrical conductance properties.« less

  4. Blue emitting ZnO nanostructures grown through cellulose bio-templates.

    PubMed

    Oudhia, Anjali; Sharma, Savita; Kulkarni, Pragya; Kumar, Rajesh

    2016-06-01

    This paper presents a green and cost-effective recipe for the synthesis of blue-emitting ZnO nanoparticles (NPs) using cellulose bio-templates. Azadirachta indica (neem) leaf extract prepared in different solvents were used as biological templates to produce nanostructures of wurtzite ZnO with a particle size ~12-36 nm. A cellulose-driven capping mechanism is used to describe the morphology of ZnO NPs. The scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), Fourier transform infra-red (FTIR) and photoluminescence (PL) studies showed that solvents affect the growth process and the capping mechanism of bio-template severely. Structural changes in ZnO NPs were evident with variation in pH, dielectric constants (DC) and boiling points (BP) of solvents. Furthermore, an energy band model is proposed to explain the origin of the blue emission in the as-obtained ZnO NPs. PL excitation studies and the theoretical enthalpy values of individual defects were used to establish the association between the interstitial-zinc-related defect levels and the blue emission. Copyright © 2015 John Wiley & Sons, Ltd. Copyright © 2015 John Wiley & Sons, Ltd.

  5. Effect of annealing on the sub-bandgap, defects and trapping states of ZnO nanostructures

    NASA Astrophysics Data System (ADS)

    Wahyuono, Ruri Agung; Hermann-Westendorf, Felix; Dellith, Andrea; Schmidt, Christa; Dellith, Jan; Plentz, Jonathan; Schulz, Martin; Presselt, Martin; Seyring, Martin; Rettenmeyer, Markus; Dietzek, Benjamin

    2017-02-01

    Annealing treatment was applied to different mesoporous ZnO nanostructures prepared by wet chemical synthesis, i.e. nanoflowers (NFs), spherical aggregates (SPs), and nanorods (NRs). The sub-bandgap, defect properties as well as the trapping state characteristics after annealing were characterized spectroscopically, including ultrasensitive photothermal deflection spectroscopy (PDS), photoluminescence and photo-electrochemical methods. The comprehensive experimental analysis reveals that annealing alters both the bandgap and the sub-bandgap. The defect concentration and the density of surface traps in the ZnO nanostructures are suppressed upon annealing as deduced from photoluminescence and open-circuit voltage decay analysis. The photo-electrochemical investigations reveal that the surface traps dominate the near conduction band edge of ZnO and, hence, lead to high recombination rates when used in DSSCs. The density of bulk traps in ZnO SPs is higher than that in ZnO NFs and ZnO NRs and promote lower recombination loss between photoinjected electrons with the electrolyte-oxidized species on the surface. The highest power conversion efficiency of ZnO NFs-, ZnO SPs-, and ZnO NRs-based DSSC obtained in our system is 2.0, 4.5, and 1.8%, respectively.

  6. Structural, optical and field emission properties of urchin-shaped ZnO nanostructures.

    PubMed

    Al-Heniti, Saleh; Umar, Ahmad

    2013-01-01

    In this work, well-crystallized urchin-shaped ZnO structures were synthesized on silicon substrate by simple non-catalytic thermal evaporation process by using metallic zinc powder in the presence of oxygen as source materials for zinc and oxygen, respectively. The synthesized ZnO structures were characterized in detail in terms of their morphological, structural, optical and field emission properties. The detailed morphological investigations revealed that the synthesized structures possess urchin-shape and grown in high-density over the substrate surface. The detailed structural and optical characterizations revealed that the synthesized urchin-shaped ZnO structures are well-crystallized and exhibiting good optical properties. The field emission analysis for urchin-shaped ZnO structures exhibits a turn-on field of 4.6 V/microm. The emission current density reached to 0.056 mA/cm2 at an applied electrical field of 6.4 V/microm and shows no saturation. The calculated field enhancement factor 'beta', from the F-N plot, was found to be approximately 2.2 x 10(3).

  7. Facile synthesis of one dimensional ZnO nanostructures for DSSC applications

    NASA Astrophysics Data System (ADS)

    Marimuthu, T.; Anandhan, N.

    2016-05-01

    Development of zinc oxide (ZnO) nanostructure based third generation dye sensitized solar cell is interesting compared to conventional silicon solar cells. ZnO nanostructured thin films were electrochemically deposited onto fluorine doped tin oxide (FTO) glass substrate. The effect of ethylene-diamine-tetra-acetic acid (EDTA) on structural, morphological and optical properties is investigated using X-ray diffraction (XRD) meter, field emission scanning electron microscope (FE-SEM) and micro Raman spectroscopy. XRD patterns reveal that the prepared nanostructures are hexagonal wutrzite structures with (101) plane orientation, the nanostructure prepared using EDTA exhibits better crystallinity. FE-SEM images illustrate that the morphological changes are observed from nanorod structure to cauliflower like structure as EDTA is added. Micro Raman spectra predict that cauliflower like structure possesses a higher crystalline nature with less atomic defects compared to nanorod structures. Dye sensitized solar cell (DSSC) is constructed for the optimized cauliflower structure, and open circuit voltage, short circuit density, fill factor and efficiency are estimated from the J-V curve.

  8. Effect of synthesized ZnO nanoparticles on thermal conductivity and mechanical properties of natural rubber

    NASA Astrophysics Data System (ADS)

    Suntako, R.

    2018-01-01

    Zinc oxide (ZnO) is widely used in rubber industry as a cure activator for rubber vulcanization. In this work, comparison of cure characteristic, mechanical properties, thermal conductivity and volume swell testing in oil no.1 and oil no.3 between natural rubber (NR) filled synthesized ZnO nanoparticles (sZnO) by precipitation method and NR filled conventional ZnO (cZnO). The particle size of sZnO is 41.50 nm and specific area of 27.92 m2/g, the particle size of cZnO is 312.92 nm and specific surface area of 1.35 m2/g. It has been found that NR filled sZnO not only improves rubber mechanical properties, volume swell testing but also improves thermal conductivity and better than NR filled cZnO. Thermal conductivity of NR filled sZnO increases by 10.34%, 12.90% and 20.00%, respectively when compared with NR filled cZnO in same loading content (various concentrations of ZnO at 5, 8 and 10 parts per hundred parts of rubber). This is due to small particle size and large specific surface area of sZnO which lead to an increase in crosslinking in rubber chain and enhance heat transfer performance.

  9. ZnO thin films and nanostructures for emerging optoelectronic applications

    NASA Astrophysics Data System (ADS)

    Rogers, D. J.; Teherani, F. H.; Sandana, V. E.; Razeghi, M.

    2010-02-01

    ZnO-based thin films and nanostructures grown by PLD for various emerging optoelectronic applications. AZO thin films are currently displacing ITO for many TCO applications due to recent improvements in attainable AZO conductivity combined with processing, cost and toxicity advantages. Advances in the channel mobilities and Id on/off ratios in ZnO-based TTFTs have opened up the potential for use as a replacement for a-Si in AM-OLED and AM-LCD screens. Angular-dependent specular reflection measurements of self-forming, moth-eye-like, nanostructure arrays grown by PLD were seen to have <0.5% reflectivity over the whole visible spectrum for angles of incidence between 10 and 60 degrees. Such nanostructures may be useful for applications such as AR coatings on solar cells. Compliant ZnO layers on mismatched/amorphous substrates were shown to have potential for MOVPE regrowth of GaN. This approach could be used as a means to facilitate lift-off of GaN-based LEDs from insulating sapphire substrates and could allow the growth of InGaN-based solar cells on cheap substrates. The green gap in InGaN-based LEDs was combated by substituting low Ts PLD n-ZnO for MOCVD n-GaN in inverted hybrid heterojunctions. This approach maintained the integrity of the InGaN MQWs and gave LEDs with green emission at just over 510 nm. Hybrid n-ZnO/p-GaN heterojunctions were also seen to have the potential for UV (375 nm) EL, characteristic of ZnO NBE emission. This suggests that there was significant hole injection into the ZnO and that such LEDs could profit from the relatively high exciton binding energy of ZnO.

  10. Fabrication of nanostructured ZnO film as a hole-conducting layer of organic photovoltaic cell

    NASA Astrophysics Data System (ADS)

    Kim, Hyomin; Kwon, Yiseul; Choe, Youngson

    2013-05-01

    We have investigated the effect of fibrous nanostructured ZnO film as a hole-conducting layer on the performance of polymer photovoltaic cells. By increasing the concentration of zinc acetate dihydrate, the changes of performance characteristics were evaluated. Fibrous nanostructured ZnO film was prepared by sol-gel process and annealed on a hot plate. As the concentration of zinc acetate dihydrate increased, ZnO fibrous nanostructure grew from 300 to 600 nm. The obtained ZnO nanostructured fibrous films have taken the shape of a maze-like structure and were characterized by UV-visible absorption, scanning electron microscopy, and X-ray diffraction techniques. The intensity of absorption bands in the ultraviolet region was increased with increasing precursor concentration. The X-ray diffraction studies show that the ZnO fibrous nanostructures became strongly (002)-oriented with increasing concentration of precursor. The bulk heterojunction photovoltaic cells were fabricated using poly(3-hexylthiophene-2,5-diyl) and indene-C60 bisadduct as active layer, and their electrical properties were investigated. The external quantum efficiency of the fabricated device increased with increasing precursor concentration.

  11. Fabrication of nanostructured ZnO film as a hole-conducting layer of organic photovoltaic cell

    PubMed Central

    2013-01-01

    We have investigated the effect of fibrous nanostructured ZnO film as a hole-conducting layer on the performance of polymer photovoltaic cells. By increasing the concentration of zinc acetate dihydrate, the changes of performance characteristics were evaluated. Fibrous nanostructured ZnO film was prepared by sol-gel process and annealed on a hot plate. As the concentration of zinc acetate dihydrate increased, ZnO fibrous nanostructure grew from 300 to 600 nm. The obtained ZnO nanostructured fibrous films have taken the shape of a maze-like structure and were characterized by UV-visible absorption, scanning electron microscopy, and X-ray diffraction techniques. The intensity of absorption bands in the ultraviolet region was increased with increasing precursor concentration. The X-ray diffraction studies show that the ZnO fibrous nanostructures became strongly (002)-oriented with increasing concentration of precursor. The bulk heterojunction photovoltaic cells were fabricated using poly(3-hexylthiophene-2,5-diyl) and indene-C60 bisadduct as active layer, and their electrical properties were investigated. The external quantum efficiency of the fabricated device increased with increasing precursor concentration. PMID:23680100

  12. Enhanced photoelectrochemical property of ZnO nanorods array synthesized on reduced graphene oxide for self-powered biosensing application.

    PubMed

    Kang, Zhuo; Gu, Yousong; Yan, Xiaoqin; Bai, Zhiming; Liu, Yichong; Liu, Shuo; Zhang, Xiaohui; Zhang, Zheng; Zhang, Xueji; Zhang, Yue

    2015-02-15

    We have realized the direct synthesis of ZnO nanorods (ZnO NRs) array on reduced graphene layer (rGO), and demonstrated the enhanced photoelectrochemical (PEC) property of the rGO/ZnO based photoanode under UV irradiation compared with the pristine ZnO NRs array. The introduction of the rGO layer resulted in a favorable energy band structure for electron migration, which finally led to the efficient photoinduced charge separation. Such nanostructure was subsequently employed for self-powered PEC biosensing of glutathione in the condition of 0 V bias, with a linear range from 10 to 200 µM, a detection limit of 2.17 µM, as well as excellent selectivity, reproducibility and stability. The results indicated the rGO/ZnO nanostructure is a competitive candidate in the PEC biosensing field. Copyright © 2014 Elsevier B.V. All rights reserved.

  13. Electrical and photocatalytic properties of boron-doped ZnO nanostructure grown on PET-ITO flexible substrates by hydrothermal method

    NASA Astrophysics Data System (ADS)

    Wang, Wei; Ai, Taotao; Yu, Qi

    2017-02-01

    Boron-doped zinc oxide sheet-spheres were synthesized on PET-ITO flexible substrates using a hydrothermal method at 90 °C for 5 h. The results of X-ray diffraction and X-ray photoelectron spectroscopy indicated that the B atoms were successfully doped into the ZnO lattice, the incorporation of B led to an increase in the lattice constant of ZnO and a change in its internal stress. The growth mechanism of pure ZnO nanorods and B-doped ZnO sheet-spheres was specifically investigated. The as-prepared BZO/PET-ITO heterojunction possessed obvious rectification properties and its positive turn-on voltage was 0.4 V. The carrier transport mechanisms involved three models such as hot carrier tunneling theory, tunneling recombination, and series-resistance effect were explored. The BZO/PET-ITO nanostructures were more effective than pure ZnO to degrade the RY 15, and the degradation rate reached 41.45%. The decomposition process with BZO nanostructure followed first-order reaction kinetics. The photocurrent and electrochemical impedance spectroscopy revealed that the B-doping could promote the separation of photo-generated electron-hole pairs, which was beneficial to enhance the photocatalytic activity. The photocurrent density of B-doped and pure ZnO/PET-ITO were 0.055 mA/cm2 and 0.016 mA/cm2, respectively. The photocatalytic mechanism of the sample was analyzed by the energy band theory.

  14. Nanostructured tungsten trioxide thin films synthesized for photoelectrocatalytic water oxidation: a review.

    PubMed

    Zhu, Tao; Chong, Meng Nan; Chan, Eng Seng

    2014-11-01

    The recent developments of nanostructured WO3 thin films synthesized through the electrochemical route of electrochemical anodization and cathodic electrodeposition for the application in photoelectrochemical (PEC) water splitting are reviewed. The key fundamental reaction mechanisms of electrochemical anodization and cathodic electrodeposition methods for synthesizing nanostructured WO3 thin films are explained. In addition, the effects of metal oxide precursors, electrode substrates, applied potentials and current densities, and annealing temperatures on size, composition, and thickness of the electrochemically synthesized nanostructured WO3 thin films are elucidated in detail. Finally, a summary is given for the general evaluation practices used to calculate the energy conversion efficiency of nanostructured WO3 thin films and a recommendation is provided to standardize the presentation of research results in the field to allow for easy comparison of reported PEC efficiencies in the near future. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  15. Growth and properties of electrodeposited transparent Al-doped ZnO nanostructures

    NASA Astrophysics Data System (ADS)

    Baka, O.; Mentar, L.; Khelladi, M. R.; Azizi, A.

    2015-12-01

    Al-doped zinc oxide (AZO) nanostructures were fabricated on fluorine-doped tin-oxide (FTO)- coated glass substrates by using electrodeposition. The effects of the doping concentration of Al on the morphological, microstructural, electrical and optical properties of the nanostructures were investigated. From the field emission scanning electron microscopy (FE-SEM) observation, when the amount of Al was increased in the solution, the grains size was observed to decreases. The observed changes in the morphology indicate that Al acts as nucleation centers in the vacancy sites of ZnO and destroys the crystalline structure at high doping level. Effectively, the X-ray diffraction (XRD) analysis indicated that the undoped and the doped ZnO nanostructures has a polycrystalline nature and a hexagonal wurtzite structure with a (002) preferential orientation. The photoluminescence (PL) room-temperature measurements showed that the incorporation of Al in the Zn lattice can improve the intensity of ultraviolet (UV) emission, thus suggesting its greater prospects for use in UV optoelectronic devices.

  16. Simultaneous tuning of electric field intensity and structural properties of ZnO: Graphene nanostructures for FOSPR based nicotine sensor.

    PubMed

    Tabassum, Rana; Gupta, Banshi D

    2017-05-15

    We report theoretical and experimental realization of a SPR based fiber optic nicotine sensor having coatings of silver and graphene doped ZnO nanostructure onto the unclad core of the optical fiber. The volume fraction (f) of graphene in ZnO was optimized using simulation of electric field intensity. Four types of graphene doped ZnO nanostructures viz. nanocomposites, nanoflowers, nanotubes and nanofibers were prepared using optimized value of f. The morphology, photoluminescence (PL) spectra and UV-vis spectra of these nanostructures were studied. The peak PL intensity was found to be highest for ZnO: graphene nanofibers. The optimized value of f in ZnO: graphene nanofiber was reconfirmed using UV-vis spectroscopy. The experiments were performed on the fiber optic probe fabricated with Ag/ZnO: graphene layer and optimized parameters for in-situ detection of nicotine. The interaction of nicotine with ZnO: graphene nanostructures alters the dielectric function of ZnO: graphene nanostructure which is manifested in terms of shift in resonance wavelength. From the sensing signal, the performance parameters were measured including sensitivity, limit of detection (LOD), limit of quantification (LOQ), stability, repeatability and selectivity. The real sample prepared using cigarette tobacco leaves and analyzed using the fabricated sensor makes it suitable for practical applications. The achieved values of LOD and LOQ are found to be unrivalled in comparison to the reported ones. The sensor possesses additional advantages such as, immunity to electromagnetic interference, low cost, capability of online monitoring, remote sensing. Copyright © 2017 Elsevier B.V. All rights reserved.

  17. Luminescence of colloidal ZnO nanoparticles synthesized in alcohols and biological application of ZnO passivated by MgO

    NASA Astrophysics Data System (ADS)

    Sikora, Bożena; Fronc, Krzysztof; Kamińska, Izabela; Koper, Kamil; Stępień, Piotr; Elbaum, Danek

    2013-05-01

    This report presents the results of spectroscopic measurements of colloidal ZnO nanoparticles synthesized in various alcohols. Luminescence of colloidal ZnO was monitored under different reaction conditions to elucidate the mechanism of the visible emission. We performed the process in different alcohols, temperatures and reaction times for two different reactants: water and NaOH. Based on the presented and previously published results it is apparent that the luminescence of the nanoparticles is influenced by several competing phenomena: the formation of new nucleation centers, the growth of the nanoparticles and surface passivation. Superimposed on the above effects is a size dependent luminescence alteration resulting from the quantum confinement. The study contributes to our understanding of the origin of ZnO nanoparticles’ green emission which is important in a rational design of fluorescent probes for nontoxic biological applications. The ZnO nanoparticles were coated with a magnesium oxide layer and introduced into a HeLa cancer cell.

  18. Luminescence of colloidal ZnO nanoparticles synthesized in alcohols and biological application of ZnO passivated by MgO.

    PubMed

    Sikora, Bożena; Fronc, Krzysztof; Kamińska, Izabela; Koper, Kamil; Stępień, Piotr; Elbaum, Danek

    2013-05-15

    This report presents the results of spectroscopic measurements of colloidal ZnO nanoparticles synthesized in various alcohols. Luminescence of colloidal ZnO was monitored under different reaction conditions to elucidate the mechanism of the visible emission. We performed the process in different alcohols, temperatures and reaction times for two different reactants: water and NaOH. Based on the presented and previously published results it is apparent that the luminescence of the nanoparticles is influenced by several competing phenomena: the formation of new nucleation centers, the growth of the nanoparticles and surface passivation. Superimposed on the above effects is a size dependent luminescence alteration resulting from the quantum confinement. The study contributes to our understanding of the origin of ZnO nanoparticles' green emission which is important in a rational design of fluorescent probes for nontoxic biological applications. The ZnO nanoparticles were coated with a magnesium oxide layer and introduced into a HeLa cancer cell.

  19. New metal catalyzed syntheses of nanostructured boron nitride and alkenyldecaboranes

    NASA Astrophysics Data System (ADS)

    Chatterjee, Shahana

    The goals of the research described in this dissertation were two-fold. The first goal was to develop new methods, employing metal-catalyzed chemical vapor deposition reactions of molecular polyborane precursors, for the production of boron nitride nanostructured materials, including both boron nitride nanotubes (BNNTs) and boron nitride nanosheets (BNNS). The second goal was to develop new systematic metal-catalyzed reactions for polyboranes that would facilitate their functionalization for possible biomedical and/or materials applications. The syntheses of multi- and double-walled BNNTs were achieved with the aid of a floating nickel catalyst via the catalytic chemical vapor deposition (CCVD) of borazine (B3N3H6) or decaborane (B10H14) molecular precursors in ammonia atmospheres, with each precursor having its own advantages. While borazine is a single-source precursor containing both boron and nitrogen, the decaborane-based syntheses required the additional step of reaction with ammonia. However, the higher observed BNNT yields and the ease of handling and commercial availability of decaborane are distinct advantages. The BNNTs derived from both precursors were crystalline with highly ordered structures. The BNNTs grown at 1200 ºC from borazine were mainly double walled, with lengths up to 0.2 µm and ˜2 nm diameters. The BNNTs grown at 1200-1300 ºC from decaborane were double- and multi-walled, with the double-walled nanotubes having ˜2 nm inner diameters and the multi-walled nanotubes (˜10 walls) having ˜4-5 nm inner diameters and ˜12-14 nm outer diameters. BNNTs grown from decaborane at 1300 ºC were longer, averaging ˜0.6 µm, whereas those grown at 1200 ºC had average lengths of ˜0.2 µm. The BNNTs were characterized using scanning and transmission electron microscopies (SEM and TEM), and electron energy loss spectroscopy (EELS). This floating catalyst method now provides a catalytic and potentially scalable route to BNNTs with low defect density

  20. Tuning the nanostructures and optical properties of undoped and N-doped ZnO by supercritical fluid treatment

    NASA Astrophysics Data System (ADS)

    Li, Yaping; Wang, Hui-Qiong; Chu, Tian-Jian; Li, Yu-Chiuan; Li, Xiaojun; Liao, Xiaxia; Wang, Xiaodan; Zhou, Hua; Kang, Junyong; Chang, Kuan-Chang; Chang, Ting-Chang; Tsai, Tsung-Ming; Zheng, Jin-Cheng

    2018-05-01

    Treatment of ZnO films in a supercritical fluid (SCF) has been reported to improve the performance of devices in which the treated ZnO films are incorporated; however, the mechanism of this improvement remains unclear. In this paper, we study the transformation of the surface morphologies and emission properties of ZnO films before and after SCF treatment, establishing the relationship between the treated and untreated structures and thereby enabling tuning of the catalytic or opto-electronic performance of ZnO films or ZnO-film-based devices. Both undoped and N-doped ZnO nanostructures generated by SCF treatment of films are investigated using techniques to characterize their surface morphology (scanning electron microscopy (SEM) and atomic force microscopy (AFM)) as well as room-temperature photoluminescence (RT-PL) spectroscopy. The water-mixed supercritical CO2 (W-SCCO2) technology was found to form nanostructures in ZnO films through a self-catalyzed process enabled by the Zn-rich conditions in the ZnO films. The W-SCCO2 was also found to promote the inhibition of defect luminescence by introducing -OH groups onto the films. Two models are proposed to explain the effects of the treatment with W-SCCO2. This work demonstrates that the W-SCCO2 technology can be used as an effective tool for the nanodesign and property enhancement of functional metal oxides.

  1. Voltammetric Sensor Based on Fe-doped ZnO and TiO2 Nanostructures-modified Carbon-paste Electrode for Determination of Levodopa

    NASA Astrophysics Data System (ADS)

    Anaraki Firooz, Azam; Hosseini Nia, Bahram; Beheshtian, Javad; Ghalkhani, Masoumeh

    2017-10-01

    In this study, undoped and 1 wt.% Fe-doped with ZnO, and TiO2 nanostructures were synthesized by a simple hydrothermal method without using templates. The influence of the Fe dopant on structural, optical and electrochemical response was studied by x-ray diffraction, scanning electron microscopy, UV-Vis spectra, photoluminescence spectra and electrochemical characterization system. The electrochemical response of the carbon paste electrode modified with synthesized nanostructures (undoped ZnO and TiO2 as well as doped with Fe ions) toward levodopa (L-Dopa) was studied. Cyclic voltammetry using provided modified electrodes showed electro-catalytic properties for electro-oxidation of L-Dopa and a significant reduction was observed in the anodic overvoltage compared to the bare electrode. The results indicated the presence of the sufficient dopants. The best response was obtained in terms of the current enhancement, overvoltage reduction, and reversibility improvement of the L-Dopa oxidation reaction under experimental conditions by the modified electrode with TiO2 nanoparticles doped with Fe ions.

  2. Intense ultraviolet emission from needle-like WO3 nanostructures synthesized by noncatalytic thermal evaporation

    PubMed Central

    2011-01-01

    Photoluminescence measurements showed that needle-like tungsten oxide nanostructures synthesized at 590°C to 750°C by the thermal evaporation of WO3 nanopowders without the use of a catalyst had an intense near-ultraviolet (NUV) emission band that was different from that of the tungsten oxide nanostructures obtained in other temperature ranges. The intense NUV emission might be due to the localized states associated with oxygen vacancies and surface states. PMID:21752275

  3. Controlling of ZnO nanostructures by solute concentration and its effect on growth, structural and optical properties

    NASA Astrophysics Data System (ADS)

    Kumar, Yogendra; Rana, Amit Kumar; Bhojane, Prateek; Pusty, Manojit; Bagwe, Vivas; Sen, Somaditya; Shirage, Parasharam M.

    2015-10-01

    ZnO nanostructured films were prepared by a chemical bath deposition method on glass substrates without any assistance of either microwave or high pressure autoclaves. The effect of solute concentration on the pure wurtzite ZnO nanostructure morphologies is studied. The control of the solute concentration helps to control the nanostructure to form nano-needles, and -rods. X-ray diffraction (XRD) studies revealed highly c-axis oriented thin films. Scanning electron microscopy (SEM) confirms the modification of the nanostructure dependent on the concentration. Transmission electron microscopy (TEM) results show the single crystalline electron diffraction pattern, indicating high quality nano-material. UV-vis results show the variation in the band gap from 3.20 eV to 3.14 eV with increasing concentration as the nanostructures change from needle- to rod-like. Photoluminescence (PL) data indicate the existence of defects in the nanomaterials emitting light in the yellow-green region, with broad UV and visible spectra. A sharp and strong peak is observed at ˜438 cm-1 by Raman spectroscopy, assigned to the {{{{E}}}2}{{high}} optical mode of ZnO, the characteristic peak for the highly-crystalline wurtzite hexagonal phase. The solute concentration significantly affects the formation of defect states in the nanostructured films, and as a result, it alters the structural and optical properties. Current-voltage characteristics alter with the measurement environment, indicating potential sensor applications.

  4. Influence of amines as surfactant on the optical, thermal, and structural properties of nanostructured ZnO

    NASA Astrophysics Data System (ADS)

    Sehgal, Preeti; Narula, A. K.

    2015-06-01

    Zinc oxide nanoparticles were synthesized by precipitation method using triethanolamine (TEA) and hexamine (HA) as capping agents, and their effects on the optical, thermal, and morphological properties were analyzed. We have also analyzed the role of solvents on the aforementioned properties of ZnO nanoparticles. The optical properties of capped zinc oxide nanoparticles were investigated by UV-visible and fluorescent techniques. The HA@ZnO and TEA@ZnO that showed blueshift in comparison with ZnO without surfactant revealed the role of surfactant in reducing the trap sites by forming defect-free nanoparticles. TG-DTA curves indicated that optimum annealing temperature for ZnO nanoparticles was in the range of 360-469 °C depending upon the surfactant and solvent; no weight loss was observed above 469 °C. Synthesized ZnO nanoparticles had pure wurtzite structure as elucidated by X-ray diffraction studies (XRD). Scanning electron microscope revealed that the ZnO synthesized in isopropyl alcohol had spherical morphology, whereas ZnO nanoparticles synthesized in methanol had agglomerate sheet-like structure. The average size of the nanocrystal was estimated around 85-169 nm for ZnO.

  5. Enabling antibacterial coating via bioinspired mineralization of nanostructured ZnO on fabrics under mild conditions.

    PubMed

    Manna, Joydeb; Begum, Gousia; Kumar, K Pranay; Misra, Sunil; Rana, Rohit K

    2013-05-22

    Herein, we present an environmentally benign method capable of mineralization and deposition of nanomaterials to introduce antibacterial functionalities into cotton fabrics under mild conditions. Similar to the way in which many naturally occurring biominerals evolve around the living organism under ambient conditions, this technique enables flexible substrates like the cotton fabric to be coated with inorganic-based functional materials. Specifically, our strategy involves the use of long-chain polyamines known to be responsible in certain biomineralization processes, to nucleate, organize, and deposit nanostructured ZnO on cotton bandage in an aqueous solution under mild conditions of room temperature and neutral pH. The ZnO-coated cotton bandages as characterized by SEM, confocal micro-Raman spectroscopy, XRD, UV-DRS, and fluorescence microscopy demonstrate the importance of polyamine in generating a stable and uniform coating of spindle-shaped ZnO particles on individual threads of the fabric. As the coating process requires only mild conditions, it avoids any adverse effect on the thermal and mechanical properties of the substrate. Furthermore, the ZnO particles on cotton fabric show efficient antibacterial activity against both gram-positive and gram-negetive bacteria. Therefore, the developed polyamine mediated bioinspired coating method provides not only a facile and "green" synthesis for coating on flexible substrate but also the fabrication of antibacterial enabled materials for healthcare applications.

  6. Mechanisms of electron transport and recombination in ZnO nanostructures for dye-sensitized solar cells.

    PubMed

    Vega-Poot, Alberto G; Macías-Montero, Manuel; Idígoras, Jesus; Borrás, Ana; Barranco, Angel; Gonzalez-Elipe, Agustín R; Lizama-Tzec, Francisco I; Oskam, Gerko; Anta, Juan A

    2014-04-14

    ZnO is an attractive material for applications in dye-sensitized solar cells and related devices. This material has excellent electron-transport properties in the bulk but its electron diffusion coefficient is much smaller in mesoporous films. In this work the electron-transport properties of two different kinds of dye-sensitized ZnO nanostructures are investigated by small-perturbation electrochemical techniques. For nanoparticulate ZnO photoanodes prepared via a wet-chemistry technique, the diffusion coefficient is found to reproduce the typical behavior predicted by the multiple-trapping and the hopping models, with an exponential increase with respect to the applied bias. In contrast, in ZnO nanostructured thin films of controlled texture and crystallinity prepared via a plasma chemical vapor deposition method, the diffusion coefficient is found to be independent of the electrochemical bias. This observation suggests a different transport mechanism not controlled by trapping and electron accumulation. In spite of the quite different transport features, the recombination kinetics, the electron-collection efficiency and the photoconversion efficiency are very similar for both kinds of photoanodes, an observation that indicates that surface properties rather than electron transport is the main efficiency-determining factor in solar cells based on ZnO nanostructured photoanodes. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  7. Nucleation effect and growth mechanism of ZnO nanostructures by electrodeposition from aqueous zinc nitrate baths

    NASA Astrophysics Data System (ADS)

    Sun, Sujuan; Jiao, Shujie; Zhang, Kejun; Wang, Dongbo; Gao, Shiyong; Li, Hongtao; Wang, Jinzhong; Yu, Qingjiang; Guo, Fengyun; Zhao, Liancheng

    2012-11-01

    We presented a systematic study of the nucleation effect and growth mechanism of ZnO nanostructures from electrolyte mixed with different concentration of Zn(NO3)2·6H2O and KCl by cathodic electrochemical deposition. Scanning electron microscopy images reveal that the concentration of Zn(NO3)2·6H2O is important to control the dimension and nucleation rate, which 1D ZnO nanostructures with smaller diameters and rougher facets are formed at lower Zn(NO3)2 precursor concentration(1 mM) and dense and well-defined nanorods are achieved above 5 mM. We also found other major effects of KCl besides as a supporting electrolyte. A high [Cl-] not only makes the transition of morphology from 1D to 2D, but also has important influence on the nucleation in the initial stage in electrodeposition. Very sparse ZnO nanoclusters composed of two dimensional nanosheets evolve from dense ZnO nanotowers when the KCl supporting electrolyte concentration is added to 2 M. Thus, altering the content of Zn(NO3)2 precursor and KCl is a effective method to obtain ZnO nanostructures with different morphology for more applications.

  8. Fabrication of Flower-like ZnO Micro/Nanostructures for Photodegradation of Pre-treated Palm Oil Mill Effluent

    NASA Astrophysics Data System (ADS)

    Lam, Sze-Mun; Wong, Kok-Ann; Sin, Jin-Chung

    2018-01-01

    Flower-like ZnO micro/nanostructures were fabricated by a simple and surfactant-free reflux method. X-ray diffraction findings showed that the prepared ZnO product was highly crystallite with hexagonal wurtzite structure. The band gap energy of ZnO sample was measured to be 3.18 eV via an optical reflectance spectrum. The flower-like morphological features of ZnO micro/nanostructures were witnessed through field-emission scanning electron microscopy. Such micro/nanoparticles could be used in the photodegradation of pre-treated palm oil mil effluent (POME) under UV irradiation.

  9. Effect of growth parameters on the optical properties of ZnO nanostructures grown by simple solution methods

    NASA Astrophysics Data System (ADS)

    Kothari, Anjana

    2017-05-01

    ZnO, a wide band gap semiconductor is of significant interest for a range of practical applications. One of the highly attractive features of ZnO is to grow variety of nanostructures by using low-cost techniques. In this paper, we report deposition of ZnO nanostructure rod-arrays (NRA) via low-temperature, solution-based deposition techniques such as chemical bath deposition (CBD) and microwave-assisted chemical bath deposition (MACBD). A detailed study of film deposition parameters such as variation in concentration of precursors and deposition temperature has been carried out. Compositional and structural study of the films has been done by X-ray Diffractometer to know the phase and purity of the final product. Morphological study of these structures has been carried out by Scanning Electron Microscopy. Optical study such as transmittance and diffuse reflectance of the films has been carried out as a function of growth parameters.

  10. Oxygen vacancy mediated enhanced photo-absorption from ZnO(0001) nanostructures fabricated by atom beam sputtering

    SciTech Connect

    Solanki, Vanaraj; Joshi, Shalik R.; Mishra, Indrani

    2016-08-07

    The nanoscale patterns created on the ZnO(0001) surfaces during atom beam irradiation have been investigated here for their photo absorption response. Preferential sputtering, during irradiation, promotes Zn-rich zones that serve as the nucleation centers for the spontaneous creation of nanostructures. Nanostructured surfaces with bigger (78 nm) nanodots, displaying hexagonal ordering and long ranged periodic behavior, show higher photo absorption and a ∼0.09 eV reduced bandgap. These nanostructures also demonstrate higher concentration of oxygen vacancies which are crucial for these results. The enhanced photo-response, as observed here, has been achieved in the absence of any dopant elements.

  11. Influence of ZnO nanostructures in liquid crystal interfaces for bistable switching applications

    NASA Astrophysics Data System (ADS)

    Pal, Kaushik; Zhan, Bihong; Madhu Mohan, M. L. N.; Schirhagl, Romana; Wang, Guoping

    2015-12-01

    The controlled fabrication of nanometer-scale objects is without doubt one of the central issues in current science and technology. In this article, we exhibit a simple, one-step bench top synthesis of zinc oxide nano-tetrapods and nano-spheres which were tailored by the facial growth of nano-wires (diameter ≈ 24 nm; length ≈ 118 nm) and nano-cubes (≈395 nm edge) to nano-sphere (diameter ≈ 585 nm) appeaded. The possibilities of inexpensive, simple solvo-chemical synthesis of nanostructures were considered. In this article, a successful attempt has been made that ZnO nano-structures dispersed on well aligned hydrogen bonded liquid crystals (HBLC) comprising azelaic acid (AC) with p-n-alkyloxy benzoic acid (nBAO) by varying the respective alkyloxy carbon number (n = 5). The dispersion of nanomaterials with HBLC is an effective route to enhance the existing functionalities. A series of these composite materials were analyzed by polarizing optical microscope's electro-optical switching. An interesting feature of AC + nBAO is the inducement of tilted smectic G phase with increasing carbon chain length. Phase diagrams of the above hybrid ZnO nanomaterial influenced LC complex and pure LC were constructed and compared. The switching times, the contrast ratio and spontaneous polarization of the nanostructures-HBLC composite film were carried out by systematic investigation. The sample preparation parameters, such as the curing time and curing intensity were optimized. The critical applied voltage to achieve the switching bi-stability of our device is only 4.5 V, which is approximately twice its threshold voltage for Freedericksz transition. This performance puts the hybrid structure at the top level in the state of the art in application oriented research in optics of liquid crystalline composite materials.

  12. Acaricidal, pediculicidal and larvicidal activity of synthesized ZnO nanoparticles using Momordica charantia leaf extract against blood feeding parasites.

    PubMed

    Gandhi, P Rajiv; Jayaseelan, C; Mary, R Regina; Mathivanan, D; Suseem, S R

    2017-10-01

    The aim of the present study was to evaluate the acaricidal, pediculicidal and larvicidal effect of synthesized zinc oxide nanoparticles (ZnO NPs) using Momordica charantia leaf extract against the larvae of Rhipicephalus (Boophilus) microplus, adult of Pediculus humanus capitis, and the larvae of Anopheles stephensi, Culex quinquefasciatus. The ZnO NPs were characterized by using UV, XRD, FTIR and SEM-EDX. The SEM image confirms that the synthesized nanoparticles were spherical in shape with a size of 21.32 nm. The results of GC-MS analysis indicates the presence of the major compound of Nonacosane (C 29 H 60 ) in the M. charantia leaf extract. Cattle tick, head lice and mosquito larvae were exposed to a varying concentrations of the synthesized ZnO NPs and M. charantia leaf extract for 24 h. Compared to the leaf aqueous extract, biosynthesized ZnO NPs showed higher toxicity against R. microplus, P. humanus capitis, An. stephensi, and Cx. Quinquefasciatus with the LC 50 values of 6.87, 14.38, 5.42, and 4.87 mg/L, respectively. The findings revealed that synthesized ZnO NPs possess excellent anti-parasitic activity. These results suggest that the green synthesized ZnO NPs has the potential to be used as an ideal ecofriendly approach for the control of R. microplus, P. humanus capitis and the mosquito larvae of An. Stephensi and Cx. quinquefasciatus. Copyright © 2017 Elsevier Inc. All rights reserved.

  13. Influence of External Gaseous Environments on the Electrical Properties of ZnO Nanostructures Obtained by a Hydrothermal Method

    PubMed Central

    Procek, Marcin; Pustelny, Tadeusz; Stolarczyk, Agnieszka

    2016-01-01

    This paper deals with experimental investigations of ZnO nanostructures, consisting of a mixture of nanoparticles and nanowires, obtained by the chemical (hydrothermal) method. The influences of both oxidizing (NO2) and reducing gases (H2, NH3), as well as relative humidity (RH) on the physical and chemical properties of ZnO nanostructures were tested. Carrier gas effect on the structure interaction with gases was also tested; experiments were conducted in air and nitrogen (N2) atmospheres. The effect of investigated gases on the resistance of the ZnO nanostructures was tested over a wide range of concentrations at room temperature (RT) and at 200 °C. The impact of near- ultraviolet (UV) excitation (λ = 390 nm) at RT was also studied. These investigations indicated a high response of ZnO nanostructures to small concentrations of NO2. The structure responses to 1 ppm of NO2 amounted to about: 600% in N2/230% in air at 200 °C (in dark conditions) and 430% in N2/340% in air at RT (with UV excitation). The response of the structure to the effect of NO2 at 200 °C is more than 105 times greater than the response to NH3, and more than 106 times greater than that to H2 in the relation of 1 ppm. Thus the selectivity of the structure for NO2 is very good. What is more, the selectivity to NO2 at RT with UV excitation increases in comparison at elevated temperature. This paper presents a great potential for practical applications of ZnO nanostructures (including nanoparticles) in resistive NO2 sensors. PMID:28335355

  14. Influence of rare earth ions on microstructural and optical properties of ZnO nanostructures

    SciTech Connect

    Riyajuddin, Sk., E-mail: riyaj5303@gmail.com; Ahmad, Shabbir; Faizan, M.

    2016-05-23

    Pure and 3% rare earth ions (Nd{sup 3+} & Gd{sup 3+}) doped ZnO samples were synthesized by sol-gel method, followed by annealing at temperature 450°C for 2hr. The samples were characterized by XRD, FTIR and UV-visible spectroscopy. XRD result confirmed single phase nature of all samples with crystalline structure. The average crystallite size of the doped samples found to be decreases as caculated using Debye-Scherrer’s formula. FTIR spectra indicate absorption band centered at 464 cm{sup −1} which is attributed to Zn-O lattice vibration. It confirms the formaton of compounds. UV-visible spectroscopy was used to study the optical properties and band gapmore » of the synthesised materials using Tauc’s relation.« less

  15. Growth mechanism, surface and optical properties of ZnO nanostructures deposited on various Au-seeded thickness obtained by mist-atomization

    SciTech Connect

    Afaah, A. N., E-mail: afaahabdullah@yahoo.com; Aadila, A., E-mail: aadilaazizali@gmail.com; Asib, N. A. M., E-mail: amierahasib@yahoo.com

    2016-07-06

    In this paper, growth mechanisms of ZnO nanostructures on non-seeded glass, 6 nm and 12 nm Au seed layer obtained by mist-atomization was proposed. ZnO films were successfully deposited on glass substrate with different thickness of Au seed layer i.e. 6 nm and 12 nm. The surface and optical properties of the prepared samples were investigated using Field emission scanning electron microscopy (FESEM) and photoluminescence (PL). FESEM micrograph show that ZnO nanostructure deposited on 6 nm Au seed layer has uniform formation and well distributed. From PL spectroscopy, the UV emission shows that ZnO deposited on 6 nm Au seedmore » layer has the more intense UV intensity which proved that high crystal quality of nanostructured ZnO deposited on 6 nm Au seed layer.« less

  16. Annealing Temperature Dependence of ZnO Nanostructures Grown by Facile Chemical Bath Deposition for EGFET pH Sensors

    NASA Astrophysics Data System (ADS)

    Bazilah Rosli, Aimi; Awang, Zaiki; Sobihana Shariffudin, Shafinaz; Herman, Sukreen Hana

    2018-03-01

    Zinc Oxide (ZnO) nanostructures were deposited using chemical bath deposition (CBD) technique in water bath at 95 °C for 4 h. Post-deposition heat treatment in air ambient at various temperature ranging from 200-600 °C for 30 min was applied in order to enhance the electrical properties of ZnO nanostructures as the sensing membrane of extended-gate field effect transistor (EGFET) pH sensor. The as-deposited sample was prepared for comparison. The samples were characterized in terms of physical and sensing properties. FESEM images showed that scattered ZnO nanorods were formed for the as-deposited sample, and the morphology of the ZnO nanorods changed to ZnO nanoflowers when the heat treatment was applied from 200-600 °C. For sensing properties, the samples heated at 300 °C showed the higher sensitivity which was 39.9 mV/pH with the linearity of 0.9792. The sensing properties was increased with the increasing annealing treatment temperature up to 300 °C before decreased drastically.

  17. Application of electrochemically deposited nanostructured ZnO layers on quartz crystal microbalance for NO2 detection

    NASA Astrophysics Data System (ADS)

    Georgieva, B.; Petrov, M.; Lovchinov, K.; Ganchev, M.; Georgieva, V.; Dimova-Malinovska, D.

    2014-11-01

    The research was fixed on sensing behavior of ZnO nanostructured (NS) films to NO2 concentrations in the environment. The ZnO NS layers are deposited by electrochemical method on quartz resonators with Au electrodes. The sorption properties of ZnO layers were defined by measuring the resonant frequency shift (Δf) of the QCM-ZnO structure for different NO2 concentrations. The measurements were based on the correlation between the frequency shift of the QCM and additional mass loading (Δm) on the resonator calculated using Sauerbrey equation for the AT-cut quartz plate. Frequency - Time Characteristics (FTCs) of the samples were measured as a function of different NO2 concentrations in order to define the sorption abilities of ZnO layers. The experiments were carried out on a special set up in a dynamical regime. From FTCs the response and the recovery times of the QCM-ZnO structure were measured with varying NO2. Frequency shift changed from 23 Hz to 58Hz when NO2 was varied in the range of 250ppm - 5000ppm. The process of sorption was estimated as reversible and the sorption as physical. The obtained results demonstrated that QCM covered with the electrochemically deposited nanostructured ZnO films can be used as application in NO2 sensors.

  18. Anomalous luminescence phenomena of indium-doped ZnO nanostructures grown on Si substrates by the hydrothermal method

    PubMed Central

    2012-01-01

    In recent years, zinc oxide (ZnO) has become one of the most popular research materials due to its unique properties and various applications. ZnO is an intrinsic semiconductor, with a wide bandgap (3.37 eV) and large exciton binding energy (60 meV) making it suitable for many optical applications. In this experiment, the simple hydrothermal method is used to grow indium-doped ZnO nanostructures on a silicon wafer, which are then annealed at different temperatures (400°C to 1,000°C) in an abundant oxygen atmosphere. This study discusses the surface structure and optical characteristic of ZnO nanomaterials. The structure of the ZnO nanostructures is analyzed by X-ray diffraction, the superficial state by scanning electron microscopy, and the optical measurements which are carried out using the temperature-dependent photoluminescence (PL) spectra. In this study, we discuss the broad peak energy of the yellow-orange emission which shows tendency towards a blueshift with the temperature increase in the PL spectra. This differs from other common semiconductors which have an increase in their peak energy of deep-level emission along with measurement temperature. PMID:22647253

  19. Photoluminescence quenching processes by NO2 adsorption in ZnO nanostructured films

    NASA Astrophysics Data System (ADS)

    Cretı, A.; Valerini, D.; Taurino, A.; Quaranta, F.; Lomascolo, M.; Rella, R.

    2012-04-01

    The optical response by NO2 gas adsorption at different concentrations has been investigated, at room temperature, in ZnO nanostructured films grown by controlled vapor phase deposition. The variation (quenching) in the photoluminescence signal from excitonic and defects bands, due to the interactions between the oxidizing gas molecules and the sample surface, has been detected and dynamic responses and calibration curves as a function of gas concentration have been obtained and analyzed for each band. We showed that the sensing response results larger in excitonic band than in defect one and that the emission signal rises from two different quenchable and unquenchable states. A simple model was proposed in order to explain the quenching processes on the emission intensity and to correlate them to the morphological features of the samples. Finally, the reversibility of the quenching effects has also been tested at high gas concentration.

  20. Enhanced photoluminescence and heterojunction characteristics of pulsed laser deposited ZnO nanostructures

    NASA Astrophysics Data System (ADS)

    Mannam, Ramanjaneyulu; Kumar, E. Senthil; Priyadarshini, D. M.; Bellarmine, F.; DasGupta, Nandita; Ramachandra Rao, M. S.

    2017-10-01

    We report on the growth of ZnO nanostructures in different gas ambient (Ar and N2) using pulsed laser deposition technique. Despite the similar growth temperature, use of N2 ambient gas resulted in well-aligned nanorods with flat surface at the tip, whereas, nanorods grown with Ar ambient exhibited tapered tips. The Nanorods grown under N2 ambient exhibited additional Raman modes corresponding to N induced zinc interstitials. The nanorods are c-axis oriented and highly epitaxial in nature. Photoluminescence spectroscopy reveals that the UV emission can be significantly enhanced by 10 times for the nanorods grown under Ar ambient. The enhanced UV emission is attributed to the reduction in polarization electric field along the c-axis. n-ZnO nanorods/p-Si heterojunction showed rectifying I-V characteristics with a turn of voltage of 3.4 V.

  1. Structure and properties of nanostructured ZnO arrays and ZnO/Ag nanocomposites fabricated by pulsed electrodeposition

    SciTech Connect

    Kopach, V. R.; Klepikova, K. S.; Klochko, N. P., E-mail: klochko-np@mail.ru

    We investigate the structure, surface morphology, and optical properties of nanostructured ZnO arrays fabricated by pulsed electrodeposition, Ag nanoparticles precipitated from colloidal solutions, and a ZnO/Ag nanocomposite based on them. The electronic and electrical parameters of the ZnO arrays and ZnO/Ag nanocomposites are analyzed by studying the I–V and C–V characteristics. Optimal modes for fabricating the ZnO/Ag heterostructures with the high stability and sensitivity to ultraviolet radiation as promising materials for use in photodetectors, gas sensors, and photocatalysts are determined.

  2. Sulfur-Doped Zinc Oxide (ZnO) Nanostars: Synthesis and Simulation of Growth Mechanism

    DTIC Science & Technology

    2011-10-01

    Zinc Oxide ( ZnO ) Nanostars: Synthesis and Simulation of Growth Mechanism Jinhyun Cho1, Qiubao Lin2,3, Sungwoo...characterization, and ab initio simulations of star-shaped hexagonal zinc oxide ( ZnO ) nanowires. The ZnO nanostructures were synthesized by a low...Introduction Zinc oxide ( ZnO ) is a wide bandgap (3.37 eV), Ⅱ–Ⅵ semiconductor of great interest for optoelectronic applications [1–3]. Its

  3. Photocatalytic studies of electrochemically synthesized polysaccharide-functionalized ZnO nanoparticles

    NASA Astrophysics Data System (ADS)

    Kaur, Simranjeet; Kaur, Harpreet

    2018-05-01

    The present work reports the electrochemical synthesis of polysaccharide-functionalized ZnO nanoparticles using sodium hydroxide, starch, and zinc electrodes for the degradation of cationic dye (Rhodamine-B) under sunlight. Physiochemical properties of synthesized sample have been characterized by different techniques such as XRD, TEM, FESEM, EDS, IR, and UV-visible spectroscopic techniques. The influence of various factors such as effect of dye concentration, contact time, amount of photocatalyst, and pH has been studied. The results obtained from the photodegradation study showed that degradation rate of Rhodamine-B dye has been increased with increase of amount of photocatalyst and decreased with increase in initial dye concentration. Furthermore, the kinetics of the degradation has been investigated. It has been found that the photodegradation of Rhodamine-B dye follows pseudo-first-order kinetics and prepared photocatalyst can effectively degrade the cationic dye. Thus, this ecofriendly and efficient photocatalyst can be used for the treatment of dye-contaminated water. This catalyst also showed the antibacterial activity against Bacillus pumilus and Escherichia coli bacterial strains, so the synthesized nanoparticles also have the pharmaceutical properties.

  4. Microstructure, electronic structure and optical properties of combustion synthesized Co doped ZnO nanoparticles

    NASA Astrophysics Data System (ADS)

    Srinatha, N.; Nair, K. G. M.; Angadi, Basavaraj

    2015-10-01

    We report on the microstructure, electronic structure and optical properties of nanocrystalline Zn1-xCoxO (x=0, 0.01, 0.03, 0.05 and 0.07) particles prepared by solution combustion technique using L-Valine as fuel. The detailed structural and micro-structural studies were carried out by XRD, HRTEM and TEM-SAED respectively, which confirms the formation of single phased, nano-sized particles. The electronic structure was determined through NEXAFS and atomic multiplet calculations/simulations performed for various symmetries and valence states of 'Co' to determine the valance state, symmetry and crystal field splitting. The correlations between the experimental NEXAFS spectra and atomic multiplet simulations, confirms that, 'Co' present is in the 2+ valence state and substituted at the 'Zn' site in tetrahedral symmetry with crystal field splitting, 10Dq =-0.6 eV. The optical properties and 'Co' induced defect formation of as-synthesized materials were examined by using diffuse reflectance and Photoluminescence spectroscopy, respectively. Red-shift of band gap energy (Eg) was observed in Zn1-xCoxO samples due to Co (0.58 Å) substitution at Zn (0.60 Å) site of the host ZnO. Also, in PL spectra, a prominent pre-edge peak corresponds to ultraviolet (UV) emission around 360-370 nm was observed with Co concentration along with near band edge emission (NBE) of the wide band gap ZnO and all samples show emission in the blue region.

  5. Effects of 8-mer acidic peptide concentration on the morphology and photoluminescence of synthesized ZnO nanomaterials

    NASA Astrophysics Data System (ADS)

    Moon, Chung Hee; Tousi, Marzieh; Cheeney, Joseph; Ngo-Duc, Tam-Triet; Zuo, Zheng; Liu, Jianlin; Haberer, Elaine D.

    2015-11-01

    An 8-mer ZnO-binding peptide, VPGAAEHT, was identified using a M13 pVIII phage display library and employed as an additive during aqueous-based ZnO synthesis at 65 °C. Unlike most other well-studied ZnO-binding sequences which are strongly basic (pI > pH 7), the 8-mer peptide was overall acidic (pI < pH 7) in character, including only a single basic residue. The selected peptide strongly influenced ZnO nanostructure formation. Morphology and optical emission properties were found to be dependent on the concentration of peptide additive. Using lower peptide concentrations (<0.1 mM), single crystal hexagonal rods and platelets were produced, and using higher peptide concentrations (≥0.1 mM), polycrystalline layered platelets, yarn-like structures, and microspheres were assembled. Photoluminescence analysis revealed a characteristic ZnO band-edge peak, as well as sub-bandgap emission peaks. Defect-related green emission, typically associated with surface-related oxygen and zinc vacancies, was significantly reduced by the peptide additive, while blue emission, attributable to oxygen and zinc interstitials, emerged with increased peptide concentrations. Peptide-directed synthesis of ZnO materials may be useful for gas sensing and photocatalytic applications in which properly engineered morphology and defect levels have demonstrated enhanced performance.

  6. Effect of co-doping process on topography, optical and electrical properties of ZnO nanostructured

    NASA Astrophysics Data System (ADS)

    Mohamed, R.; Mamat, M. H.; Malek, M. F.; Ismail, A. S.; Yusoff, M. M.; Syamsir, S. A.; Khusaimi, Z.; Rusop, M.

    2018-05-01

    We investigated of Undoped ZnO and Magnesium (Mg)-Aluminium (Al) co-doped Zinc Oxide (MAZO) nanostructured films were prepared by sol gel spin coating technique. The surface topography was analyzed using Atomic Force Microscopy (AFM). Based on the AFM results, Root Mean Square (RMS) of MAZO films have rougher surface compared to pure ZnO films. The optical and electrical properties of thin film samples were characterized using Uv-Vis spectroscopy and two point probes, current-voltage (I-V) measurements. The transmittance spectra for both thin samples was above 80% in the visible wavelength. The MAZO film shows the highest conductivity compared to pure ZnO films. This result indicates that the improvement of carrier mobility throughout doping process and possibly contribute by extra ion charge.

  7. Antimicrobial activity of TiO2 nanostructures synthesized by hydrothermal method

    NASA Astrophysics Data System (ADS)

    Surah, Shivani Singh; Sirohi, Siddharth; Nain, Ratyakshi; Kumar, Gulshan

    2018-02-01

    Titania nanostructures were synthesized by hydrothermal method. Titanium tetrachloride was used as a precursor, sodium hydroxide was used as a solvent. Effect on their morphology by variation of parameters like temperature (110°C, 160°C and 180°C), time (15h,18h, 20h, 22h, 24h) and concentration of the solvent NaOH (5M, 8M, 10 M, 12M) were studied. The obtained TiO2 nanostructures were washed with deionized water. The structure, size, morphology of the prepared nanostructures were analyzed by SEM (scanning electron microscope), DLS (dynamic light scattering), TEM (transmission electron microscope). SEM and TEM revealed the shape, size of the nanostructures. DLS reported the particle size of prepared TiO2 nanoparticles. Polymeric films based on polyvinyl alcohol (PVA) doped with titanium dioxide nanostructures at different weight percentage (0.5, 0.75, 1,2 TiO2/PVA) were prepared using the ultra sonication and solution casting techniques. The appropriate weight of PVA was dissolved in deionized water. The mixture was magnetically stirred continuously and heated (80°C) for 4 hours, until the solution mixture becomes homogenous. Different weight percentage of TiO2 nanostructures were added to deionized water and sonicated for 3 hours to prevent the nanostructures agglomeration. The mixture was mixed with the PVA solution and magnetically stirred for 1 hour to get good dispersion without agglomeration. The final PVA /TiO2 mixture were casted in glass Petridish, were left until dry. Ultrasonication was used as a major factor for preparation in order to get better dispersion. Nanocomposite films were characterized using SEM and were found to exhibit antimicrobial properties when treated with E.coli and pseudomonas.

  8. A review on methods of synthesizing nanostructures TiO2

    NASA Astrophysics Data System (ADS)

    Munirah, S.; Nadzirah, Sh.; Khusaimi, Z.; Fazlena, H.; Rusop, M.

    2018-05-01

    Titanium dioxide (TiO2) is a well-known materials and being extensively investigated due to the stability of the chemical structure, optical, physical, and electrical properties, also its biocompatibility. There are a lot of efforts have been done to synthesis TiO2 since the previous years by using different kind of methods. In this review paper, we summarize the methods of synthesizing nanostructured TiO2.

  9. Effect of Ce doping on structural, optical and photocatalytic properties of ZnO nano-structures.

    PubMed

    Selvam, N Clament Sagaya; Vijaya, J Judith; Kennedy, L John

    2014-03-01

    A novel self-assembled pure and Ce doped ZnO nano-particles (NPs) were successfully synthesized by a simple low temperature co-precipitation method. The prepared photocatalysts were characterized by X-ray diffraction (XRD), High resolution scanning electron microscopy (HR-SEM), High resolution transmission electron microscopy (HR-TEM), diffuse reflectance spectroscopy (DRS) and Photoluminescence (PL) spectroscopy. The results indicated that the prepared photocatalysts shows a novel morphology, high crystallinity, uniform size distribution, and more defects. Photocatalytic degradation (PCD) of nonylphenol, a potent endocrine disrupting chemical in aqueous medium was investigated. Higher amount of oxygen defects exhibits enhanced PCD of nonylphenol. In addition, the influence of the Ce contents on the structure, morphology, absorption, emission and photocatalytic activity of ZnO nanoparticles (NPs) were investigated systematically. The relative PCD efficiency of pure ZnO, Ce-doped ZnO NPs and commercial TiO2 (Degussa P-25) have also been discussed.

  10. Structural and electrical properties of TiO{sub 2}/ZnO core–shell nanoparticles synthesized by hydrothermal method

    SciTech Connect

    Vlazan, P.; Ursu, D.H.; Irina-Moisescu, C.

    TiO{sub 2}/ZnO core–shell nanoparticles were successfully synthesized by hydrothermal method in two stages: first stage is the hydrothermal synthesis of ZnO nanoparticles and second stage the obtained ZnO nanoparticles are encapsulated in TiO{sub 2}. The obtained ZnO, TiO{sub 2} and TiO{sub 2}/ZnO core–shell nanoparticles were investigated by means of X-ray diffraction, transmission electron microscopy, Brunauer, Emmett, Teller and resistance measurements. X-ray diffraction analysis revealed the presence of both, TiO{sub 2} and ZnO phases in TiO{sub 2}/ZnO core–shell nanoparticles. According to transmission electron microscopy images, ZnO nanoparticles have hexagonal shapes, TiO{sub 2} nanoparticles have a spherical shape, and TiO{sub 2}/ZnO core–shellmore » nanoparticles present agglomerates and the shape of particles is not well defined. The activation energy of TiO{sub 2}/ZnO core–shell nanoparticles was about 101 meV. - Graphical abstract: Display Omitted - Highlights: • TiO{sub 2}/ZnO core–shell nanoparticles were synthesized by hydrothermal method. • TiO{sub 2}/ZnO core–shell nanoparticles were investigated by means of XRD, TEM and BET. • Electrical properties of TiO{sub 2}/ZnO core–shell nanoparticles were investigated. • The activation energy of TiO{sub 2}/ZnO core–shell nanoparticles was about E{sub a} = 101 meV.« less

  11. Acoustoelectric Effect on the Responses of SAW Sensors Coated with Electrospun ZnO Nanostructured Thin Film

    PubMed Central

    Tasaltin, Cihat; Ebeoglu, Mehmet Ali; Ozturk, Zafer Ziya

    2012-01-01

    In this study, zinc oxide (ZnO) was a very good candidate for improving the sensitivity of gas sensor technology. The preparation of an electrospun ZnO nanostructured thin film on a 433 MHz Rayleigh wave based Surface Acoustic Wave (SAW) sensor and the investigation of the acoustoelectric effect on the responses of the SAW sensor are reported. We prepared an electrospun ZnO nanostructured thin film on the SAW devices by using an electrospray technique. To investigate the dependency of the sensor response on the structure and the number of the ZnO nanoparticles, SAW sensors were prepared with different coating loads. The coating frequency shifts were adjusted to fall between 100 kHz and 2.4 MHz. The sensor measurements were performed against VOCs such as acetone, trichloroethylene, chloroform, ethanol, n-propanol and methanol vapor. The sensor responses of n-propanol have opposite characteristics to the other VOCs, and we attributed these characteristics to the elastic effect/acoustoelectric effect.

  12. On the possibility of room temperature ferromagnetism on chunk-shape BaSnO3/ZnO core/shell nanostructures

    NASA Astrophysics Data System (ADS)

    Rajamanickam, N.; Jayakumar, K.; Ramachandran, K.

    2018-04-01

    Core/shell BaSnO3/ZnO (BS-ZO) nanostructures were prepared by oxalate precipitation method and wet-chemical method. BaSnO3 (BSO) cubic perovskite structure and ZnO hexagonal wurtzite structure were confirmed by X-ray diffraction (XRD). The crystallite sizes is 23 nm, 29 nm and 27 nm for BSO, ZnO and BS-ZO, respectively. Chunk-shape and cuboids morphology observed from scanning electron microscopy (SEM) analysis. The magnetic properties were studied by VSM for bare and core-shell nano systems and the room temperature ferromagnetism observed for core-shell nanostructures. The BSO/ZnO shows enhanced coercivity and saturated magnetization as compared with BSO and ZnO nanostructures.

  13. Dimensional-Hybrid Structures of 2D Materials with ZnO Nanostructures via pH-Mediated Hydrothermal Growth for Flexible UV Photodetectors.

    PubMed

    Lee, Young Bum; Kim, Seong Ku; Lim, Yi Rang; Jeon, In Su; Song, Wooseok; Myung, Sung; Lee, Sun Sook; Lim, Jongsun; An, Ki-Seok

    2017-05-03

    Complementary combination of heterostructures is a crucial factor for the development of 2D materials-based optoelectronic devices. Herein, an appropriate solution for fabricating complementary dimensional-hybrid nanostructures comprising structurally tailored ZnO nanostructures and 2D materials such as graphene and MoS 2 is suggested. Structural features of ZnO nanostructures hydrothermally grown on graphene and MoS 2 are deliberately manipulated by adjusting the pH value of the growing solution, which will result in the formation of ZnO nanowires, nanostars, and nanoflowers. The detailed growth mechanism is further explored for the structurally tailored ZnO nanostructures on the 2D materials. Furthermore, a UV photodetector based on the dimensional-hybrid nanostructures is fabricated, which demonstrates their excellent photocurrent and mechanical durability. This can be understood by the existence of oxygen vacancies and oxygen-vacancies-induced band narrowing in the ZnO nanostructures, which is a decisive factor for determining their photoelectrical properties in the hybrid system.

  14. Positron annihilation spectroscopic studies of solvothermally synthesized ZnO nanobipyramids and nanoparticles

    NASA Astrophysics Data System (ADS)

    Ghoshal, Tandra; Biswas, Subhajit; Kar, Soumitra; Chaudhuri, Subhadra; Nambissan, P. M. G.

    2008-02-01

    Zinc oxide (ZnO) samples in the form of hexagonal-based bipyramids and particles of nanometer dimensions were synthesized through solvothermal route and characterized by x-ray diffraction and transmission electron microscopy. Positron annihilation experiments were performed to study the structural defects such as vacancies and surfaces in these nanosystems. From coincidence Doppler broadening measurements, the positron trapping sites were identified as Zn vacancies or Zn-O-Zn trivacancy clusters. The positron lifetimes, their relative intensities, and the Doppler broadened lineshape parameter S all showed characteristic changes across the nanobipyramid size corresponding to the thermal diffusion length of positrons. In large nanobipyramids, vacancies within the crystallites also trapped positrons and the effects of agglomeration of such vacancies due to increased temperatures of synthesis were reflected in the variation of the annihilation parameters with their base diameters. The sizes of the nanoparticles used were all in the limit of thermal diffusion length of positrons and the annihilation characteristics were in accordance with the decreasing contribution from surfaces with increasing particle size.

  15. Positron annihilation spectroscopic studies of solvothermally synthesized ZnO nanobipyramids and nanoparticles.

    PubMed

    Ghoshal, Tandra; Biswas, Subhajit; Kar, Soumitra; Chaudhuri, Subhadra; Nambissan, P M G

    2008-02-21

    Zinc oxide (ZnO) samples in the form of hexagonal-based bipyramids and particles of nanometer dimensions were synthesized through solvothermal route and characterized by x-ray diffraction and transmission electron microscopy. Positron annihilation experiments were performed to study the structural defects such as vacancies and surfaces in these nanosystems. From coincidence Doppler broadening measurements, the positron trapping sites were identified as Zn vacancies or Zn-O-Zn trivacancy clusters. The positron lifetimes, their relative intensities, and the Doppler broadened lineshape parameter S all showed characteristic changes across the nanobipyramid size corresponding to the thermal diffusion length of positrons. In large nanobipyramids, vacancies within the crystallites also trapped positrons and the effects of agglomeration of such vacancies due to increased temperatures of synthesis were reflected in the variation of the annihilation parameters with their base diameters. The sizes of the nanoparticles used were all in the limit of thermal diffusion length of positrons and the annihilation characteristics were in accordance with the decreasing contribution from surfaces with increasing particle size.

  16. H2O2 sensing using HRP modified catalyst-free ZnO nanorods synthesized by RF sputtering

    NASA Astrophysics Data System (ADS)

    Srivastava, Amit; Kumar, Naresh; Singh, Priti; Singh, Sunil Kumar

    2017-06-01

    Catalyst-free ( 00 l) oriented ZnO nanorods (NRs) -based biosensor for the H2O2 sensing has been reported. The (002) oriented ZnO NRs as confirmed by X-ray diffraction were successfully grown on indium tin oxide (ITO) coated glass substrate by radio frequency (RF) sputtering technique without using any catalyst. Horseradish peroxidase (HRP) enzyme was immobilized on ZnO NRs by physical adsorption technique to prepare the biosensor. In this HRP/ZnO NR/ITO bioelectrode, nafion solution was added to form a tight membrane on surface. The prepared bioelectrode has been used for biosensing measurements by electrochemical analyzer. The electrochemical studies reveal that the prepared HRP/ZnO NR/ITO biosensor is highly sensitive to the detection of H2O2 over a linear range of 0.250-10 μM. The ZnO NR-based biosensor showed lower value of detection limit (0.125 μM) and higher sensitivity (13.40 µA/µM cm2) towards H2O2. The observed value of higher sensitivity attributed to larger surface area of ZnO nanostructure for effective loading of HRP besides its high electron communication capability. In addition, the biosensor also shows lower value of enzyme's kinetic parameter (Michaelis-Menten constant, K m) of 0.262 μM which indicates enhanced enzyme affinity of HRP to H2O2. The reported biosensor may be useful for various applications in biosensing, clinical, food, and beverage industry.

  17. Piezoelectric nanogenerators based on ZnO and M13 Bacteriophage nanostructures (Conference Presentation)

    NASA Astrophysics Data System (ADS)

    Shin, Dong-Myeong; Kim, Kyujungg; Hong, Suck Won; Oh, Jin-Woo; Kim, Hyung Kook; Hwang, Yoon-Hwae

    2016-09-01

    Recently, the portable and wearable electronic devices, operated in the power range of microwatt to miliwatt, become available thank to the nanotechnology development and become an essential element for a comfortable life. Our recent research interest mainly focuses on the fabrication of piezoelectric nanogenerators based on smart nanomaterials such as zinc oxide novel nanostructure, M13 bacteriophage. In this talk, we present a simple strategy for fabricating the freestanding ZnO nanorods/graphene/ZnO nanorods double sided heterostructures. The characterization of the double sided heterostructures by using SEM, and Raman scattering spectroscopy reveals the key process and working mechanism of a formation of the heterostructure. The mechanism is discussed in detail in term of the decomposed seed layer and the vacancy defect of graphene. The approach consists of a facile one-step fabrication process and could achieve ZnO coverage with a higher number density than that of the epitaxial single heterostructure. The resulting improvement in the number density of nanorods has a direct beneficial effect on the double side heterostructured nanogenerator performance. The total output voltage and current density are improved up to 2 times compared to those of a single heterostructure due to the coupling of the piezoelectric effects from both upward and downward grown nanorods. The facile one-step fabrication process suggests that double sided heterostructures would improve the performance of electrical and optoelectrical device, such as touch pad, pressure sensor, biosensor and dye-sensitized solar cells. Further, ioinspired nanogenerators based on vertically aligned phage nanopillars are inceptively demonstrated. Vertically aligned phage nanopillars enable not only a high piezoelectric response but also a tuneable piezoelectricity. Piezoelectricity is also modulated by tuning of the protein's dipoles in each phage. The sufficient electrical power from phage nanopillars thus

  18. Robust superhydrophobic needle-like nanostructured ZnO surfaces prepared without post chemical-treatment

    NASA Astrophysics Data System (ADS)

    Velayi, Elmira; Norouzbeigi, Reza

    2017-12-01

    Robust superhydrophobic ZnO surfaces with micro/nano hybrid hierarchical structures were synthesized on the stainless steel mesh by a facile single-step chemical bath deposition (CBD) method without using further low surface energy materials. The Taguchi L16 experimental design was applied to evaluate the effects of reaction time, type and concentration of the additive, type of the chelating agent, and the molar ratio of the chelating agent to the initial zinc (II) ions. The prepared sample at the optimal conditions exhibited a sustainable and time-independent superhydrophobic behavior with the water contact angle (WCA) of 162.8° ± 2.5° and contact angle hysteresis (CAH) of 1.8° ± 0.5°. The XRD, SEM, TEM and FTIR analyses were used to characterize the prepared samples. Surface characterization using scanning electron microscopy (SEM) indicated accumulation of micro/nano branched ZnO needles on the substrate with the average diameters of ∼85 nm. After 20 abrasion cycles the optimum sample indicated an excellent mechanical robustness via exposure to the pressure of 4.7 kPa. A suitable chemical resistance to the acidic and basic droplets with the pH range of 4 and 9 was observed.

  19. Hydrogen Gas Sensing Characteristics of Nanostructured NiO Thin Films Synthesized by SILAR Method

    NASA Astrophysics Data System (ADS)

    Karaduman, Irmak; Çorlu, Tugba; Yıldırım, M. Ali; Ateş, Aytunç; Acar, Selim

    2017-07-01

    Nanostructured NiO thin films have been synthesized by a facile, low-cost successive ionic layer adsorption and reaction (SILAR) method, and the effects of the film thickness on their hydrogen gas sensing properties investigated. The samples were characterized by scanning electron microscopy (SEM), x-ray diffraction (XRD) analysis, and energy-dispersive x-ray analysis. The XRD results revealed that the crystallinity improved with increasing thickness, exhibiting polycrystalline structure. SEM studies showed that all the films covered the glass substrate well. According to optical absorption measurements, the optical bandgap decreased with increasing film thickness. The gas sensing properties of the nanostructured NiO thin films were studied as a function of operating temperature and gas concentration. The samples showed good sensing performance of H2 gas with high response. The maximum response was 75% at operating temperature of 200°C for hydrogen gas concentration of 40 ppm. These results demonstrate that nanostructured NiO thin films synthesized by the SILAR method have potential for application in hydrogen detection.

  20. Improvement of antimony sulfide photo absorber performance by interface modification in Sb2S3-ZnO hybrid nanostructures

    NASA Astrophysics Data System (ADS)

    Ali, Asad; Hasanain, Syed Khurshid; Ali, Tahir; Sultan, Muhammad

    2017-03-01

    Metal-oxide chalcogenide nanostructures as part of hybrid systems are very important for photovoltaic and optoelectronic applications. It is however known that the various interfaces within the hybrid structures play a crucial role in limiting the efficiency of these devices. Here we report on the improvement of Sb2S3 structure through modification of interface between Zn-oxide nanostructures and chalcogenides. ZnO nanorods were grown on fluorine doped tin oxide (FTO) substrate by chemical bath deposition (CBD) method. X-ray diffraction (XRD) and SEM analysis confirmed the single phase wurtzite structure and c-axis orientation of the ZnO nanorod arrays. Antimony tri-sulfide (Sb2S3) was deposited on ZnO nanords by CBD and subsequently annealed at 300 °C in argon environment for 30 min. XRD and the XPS analysis of ZnO-Sb2S3 system showed the dominant presence of Sb2O3 rather than Sb2S3. Since oxidation of Sb2S3 is understood to proceed mainly from the ZnO-Sb2S3 interface, a ZnS interlayer was introduced between ZnO nanorods and Sb2S3 by chemical route. The subsequent structural and optical properties of the ZnO-ZnS-Sb2S3 system are analyzed in detail. The introduction of sulfide interlayer prevents the oxidation of Sb2S3 which is evident from reduced oxide phase in Sb2S3. Significant improvement in the structural and optical properties of Sb2S3 are reported as compared to the parent ZnO-Sb2S3 system. This gain in the optical properties of hybrid ZnO-ZnS-Sb2S3 nanostructures is explained as being related to successful prevention of Sb2O3 formation at the Sb-ZnO interface and stabilization of the desired Sb2S3.

  1. Visible and UV photo-detection in ZnO nanostructured thin films via simple tuning of solution method.

    PubMed

    Khokhra, Richa; Bharti, Bandna; Lee, Heung-No; Kumar, Rajesh

    2017-11-08

    This study demonstrates significant visible light photo-detection capability of pristine ZnO nanostructure thin films possessing substantially high percentage of oxygen vacancies [Formula: see text] and zinc interstitials [Formula: see text], introduced by simple tuning of economical solution method. The demonstrated visible light photo-detection capability, in addition to the inherent UV light detection ability of ZnO, shows great dependency of [Formula: see text] and [Formula: see text] with the nanostructure morphology. The dependency was evaluated by analyzing the presence/percentage of [Formula: see text] and [Formula: see text] using photoluminescence (PL) and X-ray photoelectron spectroscopy (XPS) measurements. Morphologies of ZnO viz. nanoparticles (NPs), nanosheets (NSs) and nanoflowers (NFs), as a result of tuning of synthesis method contended different concentrations of defects, demonstrated different photo-detection capabilities in the form of a thin film photodetector. The photo-detection capability was investigated under different light excitations (UV; 380~420 nm, white ; λ > 420 nm and green; 490~570 nm). The as fabricated NSs photodetector possessing comparatively intermediate percentage of [Formula: see text] ~ 47.7% and [Formula: see text] ~ 13.8% exhibited superior performance than that of NPs and NFs photodetectors, and ever reported photodetectors fabricated by using pristine ZnO nanostructures in thin film architecture. The adopted low cost and simplest approach makes the pristine ZnO-NSs applicable for wide-wavelength applications in optoelectronic devices.

  2. Microwave-assisted Facile and Ultrafast Growth of ZnO Nanostructures and Proposition of Alternative Microwave-assisted Methods to Address Growth Stoppage

    NASA Astrophysics Data System (ADS)

    Rana, Abu Ul Hassan Sarwar; Kang, Mingi; Kim, Hyun-Seok

    2016-04-01

    The time constraint in the growth of ZnO nanostructures when using a hydrothermal method is of paramount importance in contemporary research, where a long fabrication time rots the very essence of the research on ZnO nanostructures. In this study, we present the facile and ultrafast growth of ZnO nanostructures in a domestic microwave oven within a pressurized environment in just a few minutes. This method is preferred for the conventional solution-based method because of the ultrafast supersaturation of zinc salts and the fabrication of high-quality nanostructures. The study of the effect of seed layer density, growth time, and the solution’s molar concentration on the morphology, alignment, density, and aspect ratio of ZnO nanorods (ZNRs) is explored. It is found in a microwave-assisted direct growth method that ~5 mins is the optimum time beyond which homogeneous nucleation supersedes heterogeneous nucleation, which results in the growth stoppage of ZNRs. To deal with this issue, we propound different methods such as microwave-assisted solution-replacement, preheating, and PEI-based growth methods, where growth stoppage is addressed and ZNRs with a high aspect ratio can be grown. Furthermore, high-quality ZnO nanoflowers and ZnO nanowalls are fabricated via ammonium hydroxide treatment in a very short time.

  3. Surface nanostructuring of thin film composite membranes via grafting polymerization and incorporation of ZnO nanoparticles

    NASA Astrophysics Data System (ADS)

    Isawi, Heba; El-Sayed, Magdi H.; Feng, Xianshe; Shawky, Hosam; Abdel Mottaleb, Mohamed S.

    2016-11-01

    A new approach for modification of polyamid thin film composite membrane PA(TFC) using synthesized ZnO nanoparticles (ZnO NPs) was shown to enhance the membrane performances for reverse osmosis water desalination. First, active layer of synthesis PA(TFC) membrane was activated with an aqueous solution of free radical graft polymerization of hydrophilic methacrylic acid (MAA) monomer onto the surface of the PA(TFC) membrane resulting PMAA-g-PA(TFC). Second, the PA(TFC) membrane has been developed by incorporation of ZnO NPs into the MAA grafting solution resulting the ZnO NPs modified PMAA-g-PA(TFC) membrane. The surface properties of the synthesized nanoparticles and prepared membranes were investigated using the FTIR, XRD and SEM. Morphology studies demonstrated that ZnO NPs have been successfully incorporated into the active grafting layer over PA(TFC) composite membranes. The zinc leaching from the ZnO NPs modified PMAA-g-PA(TFC) was minimal, as shown by batch tests that indicated stabilization of the ZnO NPs on the membrane surfaces. Compared with the a pure PA(TFC) and PMAA-g-PA(TFC) membranes, the ZnO NPs modified PMAA-g-PA(TFC) was more hydrophilic, with an improved water contact angle (∼50 ± 3°) over the PMAA-g-PA(TFC) (63 ± 2.5°). The ZnO NPs modified PMAA-g-PA(TFC) membrane showed salt rejection of 97% (of the total groundwater salinity), 99% of dissolved bivalent ions (Ca2+, SO42-and Mg2+), and 98% of mono valent ions constituents (Cl- and Na+). In addition, antifouling performance of the membranes was determined using E. coli as a potential foulant. This demonstrates that the ZnO NPs modified PMAA-g-PA(TFC) membrane can significantly improve the membrane performances and was favorable to enhance the selectivity, permeability, water flux, mechanical properties and the bio-antifouling properties of the membranes for water desalination.

  4. Studies of surface morphology and optical properties of ZnO nanostructures grown on different molarities of TiO{sub 2} seed layer

    SciTech Connect

    Asib, N. A. M., E-mail: amierahasib@yahoo.com; Afaah, A. N.; Aadila, A.

    Titanium dioxide (TiO{sub 2}) seed layer was prepared by using sol-gel spin-coating technique, followed by growth of 0.01 M of Zinc oxide (ZnO) nanostructures by solution-immersion. The molarities of TiO{sub 2} seed layer were varied from 1.1 M to 0.100 M on glass substrates. The nanostructures thin films were characterized by Field Emission Scanning Electrons Microscope (FESEM), Photoluminescence (PL) spectroscopy and Ultraviolet-Visible (UV-Vis) spectroscopy. FESEM images demonstrate that needle-like ZnO nanostructures are formed on all TiO{sub 2} seed layer. The smallest diameter of needle-like ZnO nanostructures (90.3 nm) were deposited on TiO{sub 2} seed layer of 0.100 M. PL spectramore » of the TiO{sub 2}: ZnO nanostructures thin films show the blue shifted emissions in the UV regions compared to the ZnO thin film. Meanwhile, UV-vis spectra of films display high absorption in the UV region and high trasparency in the visible region. The highest absorbance at UV region was recorded for sample which has 0.100 M of TiO{sub 2} seed layer.« less

  5. Electromagnetic and Microwave Absorption Properties of Carbonyl Tetrapod-Shaped Zno Nanostructures Composite Coatings

    NASA Astrophysics Data System (ADS)

    Yu, Haibo; Qin, Hui; Huang, Yunhua

    2012-08-01

    CIP/T-ZnO/EP composite coatings with carbonyl iron powders (CIP) and tetrapodshaped ZnO (T-ZnO) nanostructures as absorbers, and epoxy resin (EP) as matrix were prepared. The complex permittivity, permeability and microwave absorption properties of the coatings were investigated in the frequency range of 2-18 GHz. The effects of the weight ratio (CIP/T-ZnO/EP), the thickness and the solidification temperature on microwave absorption properties were discussed. When the weight ratio (CIP/TZnO/ EP), the thickness and the solidification temperature is 28:2:22, 1.8 mm, and 10°C, respectively, the optimal wave absorption with the minimum reflection loss (RL) value of -22.38 dB at 15.67 GHz and the bandwidth (RL<-10 dB) of 5.74 GHz was obtained, indicating that the composite coatings may have a promising application in Ku-band (12-18 GHz).

  6. Hexagonal ZnO porous plates prepared from microwave synthesized layered zinc hydroxide sulphate via thermal decomposition

    SciTech Connect

    Machovsky, Michal, E-mail: machovsky@ft.utb.cz; Polymer Centre, Faculty of Technology, Tomas Bata University in Zlin, Nam. T.G. Masaryka 275, 762 72 Zlin; Kuritka, Ivo, E-mail: ivo@kuritka.net

    2013-10-15

    Graphical abstract: - Highlights: • Zinc hydroxy sulphate was synthesized in 3 min via microwave hydrothermal route. • Zinc hydroxy sulphate was converted into mesh like porous ZnO by calcining at 900°. • The process of transformation is topotactic. - Abstract: Layered zinc hydroxide sulphate (ZHS) was prepared by microwave-assisted hydrothermal precipitation of zinc sulphate monohydrate with hexamethylenetetramine. Under ambient conditions, the structure of ZHS determined by X-ray diffraction (XRD) was found to be a mixture of zinc hydroxide sulphate pentahydrate Zn{sub 4}SO{sub 4}(OH){sub 6}·5H{sub 2}O and tetrahydrate Zn{sub 4}SO{sub 4}(OH){sub 6}·4H{sub 2}O. Fourier transform infrared (FTIR) spectroscopy was usedmore » for characterization of the prepared materials. Based on the interpretation of ZHS's thermal decomposition profile obtained by thermogravimetric analysis, ZnO of high purity was prepared by calcination at 900 °C for 2 h. The structure of the resulting ZnO was confirmed by the XRD. The morphology examination by scanning electron microscopy revealed a porous mesh-like ZnO structure developed from the ZHS precursor at the expense of mass removal due to the release of water and sulphate during the calcination.« less

  7. Nanostructured ZnO in a Metglas/ZnO/Hemoglobin Modified Electrode to Detect the Oxidation of the Hemoglobin Simultaneously by Cyclic Voltammetry and Magnetoelastic Resonance

    PubMed Central

    Sagasti, Ariane; Bouropoulos, Nikolaos; Kouzoudis, Dimitris; Panagiotopoulos, Apostolos; Topoglidis, Emmanuel; Gutiérrez, Jon

    2017-01-01

    In the present work, a nanostructured ZnO layer was synthesized onto a Metglas magnetoelastic ribbon to immobilize hemoglobin (Hb) on it and study the Hb’s electrochemical behavior towards hydrogen peroxide. Hb oxidation by H2O2 was monitored simultaneously by two different techniques: Cyclic Voltammetry (CV) and Magnetoelastic Resonance (MR). The Metglas/ZnO/Hb system was simultaneously used as a working electrode for the CV scans and as a magnetoelastic sensor excited by external coils, which drive it to resonance and interrogate it. The ZnO nanoparticles for the ZnO layer were grown hydrothermally and fully characterized by X-Ray Diffraction (XRD), Scanning Electron Microscopy (SEM) and photoluminescence (PL). Additionally, the ZnO layer’s elastic modulus was measured using a new method, which makes use of the Metglas substrate. For the detection experiments, the electrochemical cell was performed with a glass vial, where the three electrodes (working, counter and reference) were immersed into PBS (Phosphate Buffer Solution) solution and small H2O2 drops were added, one at a time. CV scans were taken every 30 s and 5 min after the addition of each drop and meanwhile a magnetoelastic measurement was taken by the external coils. The CV plots reveal direct electrochemical behavior of Hb and display good electrocatalytic response to the reduction of H2O2. The measured catalysis currents increase linearly with the H2O2 concentration in a wide range of 25–350 μM with a correlation coefficient 0.99. The detection limit is 25–50 μM. Moreover, the Metglas/ZnO/Hb electrode displays rapid response (30 s) to H2O2, and exhibits good stability and reproducibility of the measurements. On the other hand, the magnetoelastic measurements show a small linear mass increase versus the H2O2 concentration with a slope of 152 ng/μM, which is probably due to H2O2 adsorption in ZnO during the electrochemical reaction. No such effects were detected during the control experiment

  8. Nanostructured ZnO in a Metglas/ZnO/Hemoglobin Modified Electrode to Detect the Oxidation of the Hemoglobin Simultaneously by Cyclic Voltammetry and Magnetoelastic Resonance.

    PubMed

    Sagasti, Ariane; Bouropoulos, Nikolaos; Kouzoudis, Dimitris; Panagiotopoulos, Apostolos; Topoglidis, Emmanuel; Gutiérrez, Jon

    2017-07-25

    In the present work, a nanostructured ZnO layer was synthesized onto a Metglas magnetoelastic ribbon to immobilize hemoglobin (Hb) on it and study the Hb's electrochemical behavior towards hydrogen peroxide. Hb oxidation by H₂O₂ was monitored simultaneously by two different techniques: Cyclic Voltammetry (CV) and Magnetoelastic Resonance (MR). The Metglas/ZnO/Hb system was simultaneously used as a working electrode for the CV scans and as a magnetoelastic sensor excited by external coils, which drive it to resonance and interrogate it. The ZnO nanoparticles for the ZnO layer were grown hydrothermally and fully characterized by X-Ray Diffraction (XRD), Scanning Electron Microscopy (SEM) and photoluminescence (PL). Additionally, the ZnO layer's elastic modulus was measured using a new method, which makes use of the Metglas substrate. For the detection experiments, the electrochemical cell was performed with a glass vial, where the three electrodes (working, counter and reference) were immersed into PBS (Phosphate Buffer Solution) solution and small H₂O₂ drops were added, one at a time. CV scans were taken every 30 s and 5 min after the addition of each drop and meanwhile a magnetoelastic measurement was taken by the external coils. The CV plots reveal direct electrochemical behavior of Hb and display good electrocatalytic response to the reduction of H₂O₂. The measured catalysis currents increase linearly with the H₂O₂ concentration in a wide range of 25-350 μM with a correlation coefficient 0.99. The detection limit is 25-50 μM. Moreover, the Metglas/ZnO/Hb electrode displays rapid response (30 s) to H₂O₂, and exhibits good stability and reproducibility of the measurements. On the other hand, the magnetoelastic measurements show a small linear mass increase versus the H₂O₂ concentration with a slope of 152 ng/μM, which is probably due to H₂O₂ adsorption in ZnO during the electrochemical reaction. No such effects were detected during

  9. Controlling the Optical and Magnetic Properties of Nanostructured Cuprous Oxide Synthesized from Waste Electric Cables

    NASA Astrophysics Data System (ADS)

    Abdelbasir, S. M.; El-Sheikh, S. M.; Rashad, M. M.; Rayan, D. A.

    2018-03-01

    Cuprous oxide Cu2O nanopowders were purposefully synthesised from waste electric cables (WECs) via a simple precipitation route at room temperature using lactose as a reducing agent. In this regard, dimethyl sulfoxide (DMSO) was first applied as an organic solvent for the dissolution of the cable insulating materials. Several parameters were investigated during dissolution of WECs such as dissolution temperature, time and solid/liquid ratio to determine the dissolution percentage of the insulating materials in DMSO. The morphology and the optical properties of the formed Cu2O particles were investigated using X-ray diffraction (XRD), field emission-scanning electron microscopy (FE-SEM), Fourier-transform infrared spectroscopy and UV-visible-near IR spectrophotometer. XRD data confirmed the presence of single crystalline phase of Cu2O nanoparticles. FE-SEM and TEM images revealed spherical, cubic and octahedral shapes with the various particle sizes ranged from 16 to 57 nm depending on the synthesis conditions. A possible mechanism explaining the Cu2O nanostructures formation was proposed. The band gap energies of the Cu2O nanostructures were estimated and the values were located between 1.5 and 2.08 eV. Photoluminescence spectroscopy analysis clearly showed a noticeably blue-shifted emission for the synthesized samples compared to spectrum of the bulk. Eventually, magnetic properties of the synthesized nanoparticles have been measured by vibrating sample magnetometer and the attained results implied that the synthesized particles are weakly ferromagnetic in nature at normal temperature.

  10. Growth stimulation of Bacillus cereus and Pseudomonas putida using nanostructured ZnO thin film as transducer element

    NASA Astrophysics Data System (ADS)

    Loukanov, Alexandre; Filipov, Chavdar; Valcheva, Violeta; Lecheva, Marta; Emin, Saim

    2015-04-01

    The semiconductor zinc oxide nanomaterial (ZnO or ZnO:H) is widely used in advanced biosensor technology for the design of highly-sensitive detector elements for various applications. In the attempt to evaluate its effect on common microorganisms, two types of nanostructured transducer films have been used (average diameter 600-1000 nm). They have been prepared by using both wet sol-gel method and magnetron sputtering. Their polycrystalline structure and specific surface features have been analyzed by X-ray diffraction (XRD), scanning electron microscope, and atomic force microscope. The assessment of growth stimulation of bacteria was determined using epifluorescent microscope by cell staining with Live/Dead BacLight kit. In our experiments, the growth stimulation of Gram-positive and Gram-negative bacteria on nanostructured ZnO film is demonstrated by Bacillus cereus and Pseudomonas putida. These two bacterial species have been selected, because they are well known and studied in biosensor technologies, with structural difference of their cell walls. These pathogens are easy for with common source in the liquid food or some commercial products. Our data has revealed that the method of transducer film preparation influences strongly bacterial inhibition and division. These results present the transforming signal precisely, when ZnO is used in biosensor applications.

  11. Effective tuning of electron charge and spin distribution in a dot-ring nanostructure at the ZnO interface

    NASA Astrophysics Data System (ADS)

    Chakraborty, Tapash; Manaselyan, Aram; Barseghyan, Manuk

    2018-05-01

    Electronic states and the Aharonov-Bohm effect in ZnO quantum dot-ring nanostructures containing few interacting electrons reveal several unique features. We have shown here that in contrast to the dot-rings made of conventional semiconductors, such as InAs or GaAs, the dot-rings in ZnO heterojunctions demonstrate several unique characteristics due to the unusual properties of quantum dots and rings in ZnO. In particular the energy spectra of the ZnO dot-ring and the Aharnov-Bohm oscillations are strongly dependant on the electron number in the dot or in the ring. Therefore even small changes of the confinement potential, sizes of the dot-ring or the magnetic field can drastically change the energy spectra and the behavior of Aharonov-Bohm oscillations in the system. Due to this interesting phenomena it is possible to effectively control with high accuracy the electron charge and spin distribution inside the dot-ring structure. This controlling can be achieved either by changing the magnetic field or the confinement potentials.

  12. Nanostructured ZnO films with various morphologies prepared by ultrasonic spray pyrolysis and its growing process

    NASA Astrophysics Data System (ADS)

    Ma, H. L.; Liu, Z. W.; Zeng, D. C.; Zhong, M. L.; Yu, H. Y.; Mikmekova, E.

    2013-10-01

    Nanostructured ZnO films were prepared by the ultrasonic spray pyrolysis method using Zn(CH3COO)2·2H2O as a precursor. The effects of substrate temperature (Ts) on the morphology and properties were systematically studied. As the Ts increased from 430 °C to 610 °C, the morphology of the film transforms from closed packed nanosheets to dense nanocrystalline film and then to hexagonal nanorod array. The dense film formed at a temperature of 550 °C has the lowest electric resistivity and highest carrier concentration. The optical transmittance for all prepared samples was higher than 90%. The photoluminescence (PL) properties varied with the Ts due to the internal defect difference. The growth mechanism of ZnO film involves island growth and diffusion, which was evident by observing the samples prepared at various times.

  13. Structural and optical studies of hydrothermally synthesized MoS{sub 2} nanostructures

    SciTech Connect

    Chacko, Levna; Swetha, A. K.; Aneesh, P. M., E-mail: aneeshpm@cukerala.ac.in

    2016-05-06

    Transition-metal dichalcogenides like molybdenum disulphide have intrigued intensive interest as two-dimensional (2D) materials beyond extensively studied graphene due to their unique electronic and optical properties. Here we report the hydrothermal synthesis of MoS{sub 2} nanostructures without the addition of any surfactants. The structural and optical properties of the synthesized samples were characterized by various techniques, including X-ray diffraction (XRD), UV-Vis absorption, photoluminescence (PL), and Raman analysis. XRD and Raman spectroscopic studies confirm the formation of hexagonal phase and well ordered stacking of S-Mo-S layers. The increased lattice parameters of MoS{sub 2} samples are due to the stress or strain inducedmore » bending and folding of the layers. The synthesized MoS{sub 2} nanostructures shows a large optical absorption in 300-700 nm region and strong luminescence at 640 nm. In addition, the optical results demonstrates the quantum confinement in layered d-electron material MoS{sub 2} that can lead to engineer its various properties for electronic and optoelectronic applications.« less

  14. Growth parameter dependent structural and optical properties of ZnO nanostructures on Si substrate by a two-zone thermal CVD.

    PubMed

    Lee, Hee Kwan; Yu, Jae Su

    2012-04-01

    We investigated the effect of growth parameters on the structural and optical properties of the ZnO nanostructures (NSs) grown on Au-coated Si substrate by a two-zone thermal chemical vapor deposition. The morphologies of ZnO NSs were controlled by various growth parameters, such as growth temperature, O2 flow rate, and working pressure, for different thicknesses of Au layer. The nanorod-like ZnO NSs were formed at 915 degrees C and the growth of two-dimensional structures, i.e., nanosheets, was enhanced with the increase of growth temperature up to 965 degrees C. It was found that the low working pressure contributed to improvement in vertical alignment and uniformity of ZnO NSs. The Zn/O atomic % ratio, which plays a key role in the growth mechanism of ZnO NSs, was changed by the growth parameters. The Zn/O atomic % ratio was increased with increasing the growth temperature, while it was decreased with increasing the working pressure. Under proper O2 flow rate, the ZnO nanorods with good crystallinity were fabricated with a Zn/O atomic % ratio of -0.9. For various growth parameters, the photoluminescence emission was slightly shifted with the ultraviolet emission related to the near band edge transition.

  15. Protein functionalization of ZnO nanostructure exhibits selective and enhanced toxicity to breast cancer cells through oxidative stress-based cell death mechanism.

    PubMed

    Mahanta, Sailendra; Prathap, S; Ban, Deependra Kumar; Paul, Subhankar

    2017-08-01

    Zinc oxide nanostructure (ZnONS) was chemically synthesized and functionalized (FZnONS BLA ) with a small protein bovine α-lactalbumin (BLA) by chemical cross-linking methods. Both nano-structures were characterized using various techniques such as electron microscopy, dynamic light scattering (DLS), UV-Vis spectroscopy, FT-IR, photo-luminescence and X-ray diffraction. Electron microscopy and DLS analysis revealed their (ZnONS and FZnONS BLA ) average size of 200nm and 450nm, respectively. When cytotoxicity of both the nanostructures were assessed in breast cancer cells MCF-7 and MDAMB231 by MTT assay and PI/Annexin V staining (FACS), FZnONS BLA demonstrated higher cell death than ZnONS primarily due to generation of intracellular reactive oxygen species (ROS). Our experimental results also suggested that such enhanced toxicity was due to the lethal structural variant of BLA in FZnONS BLA as well as higher cellular uptake than ZnONS by cancer cells. The death kinetics study with time in cancer cells further proved that FZnONS BLA caused toxicity much faster than ZnONS, thus suggested a strong role of lethal variant of BLA in FZnONS BLA as a cytotoxic agent in cancer cells. Furthermore, FZnONS BLA demonstrated excellent cytocompatibility (normal cells) and hemocompatibility compared to ZnONS. Hence, considering the biodegradable nature of ZnO nonmaterial, our results demonstrated that BLA functionalized ZnONS could be used to develop a suitable therapeutic strategy in cancer. Copyright © 2017. Published by Elsevier B.V.

  16. Hybrid nanostructure heterojunction solar cells fabricated using vertically aligned ZnO nanotubes grown on reduced graphene oxide.

    PubMed

    Yang, Kaikun; Xu, Congkang; Huang, Liwei; Zou, Lianfeng; Wang, Howard

    2011-10-07

    Using reduced graphene oxide (rGO) films as the transparent conductive coating, inorganic/organic hybrid nanostructure heterojunction photovoltaic devices have been fabricated through hydrothermal synthesis of vertically aligned ZnO nanorods (ZnO-NRs) and nanotubes (ZnO-NTs) on rGO films followed by the spin casting of a poly(3-hexylthiophene) (P3HT) film. The data show that larger interfacial area in ZnO-NT/P3HT composites improves the exciton dissociation and the higher electrode conductance of rGO films helps the power output. This study offers an alternative to manufacturing nanostructure heterojunction solar cells at low temperatures using potentially low cost materials.

  17. Growth of ZnO nanorods on glass substrate deposited using dip coating method

    NASA Astrophysics Data System (ADS)

    Rani, Rozina Abdul; Ghafar, Safiah Ab; Zoolfakar, Ahmad Sabirin; Rusop, M.

    2018-05-01

    ZnO unique properties make it attractive for electronics and optoelectronics application. There are varieties synthesis of ZnO nanostructure but one of the best ways is by using dip coating method due to its simplicity, low cost and reliability. This research investigated the effect of precursor concentration on the morphology of ZnO nanorods using dip coating technique. ZnO nanorods is synthesized by using zinc nitrate as precursor and glass slide as substrate. The morphology of ZnO is characterized using Field Emission Scanning Electron Microscope (FESEM). By using different concentration of precursor, each outcome demonstrated diverse morphologies.

  18. Rapidly synthesized ZnO nanowires by ultraviolet decomposition process in ambient air for flexible photodetector.

    PubMed

    Wu, Jyh Ming; Chen, Yi-Ru; Lin, Yu-Hung

    2011-03-01

    We are the first group to use a simple direct ultraviolet light (UV, λ=365 nm, I=76 mW cm(-2)) in a decomposition process to fabricate ZnO nanowires on a flexible substrate using a zinc acetylacetonate hydrate precursor in ambient air. ZnO nanocrystal (or nanowire) production only requires three to ten minutes. A field emission scanning electron microscopy (FESEM) image reveals a high aspect ratio of the ZnO nanowires, which are grown on a substrate with a diameter of ∼50-100 nm, and a length of up to several hundred microns. High resolution transmission electron microscopy (HRTEM) images reveal that the nanowires consist of many single crystalline ZnO nanoparticles that grow along the c axis, which suggests an oriented attachment process. A potential application for flexible UV photodetectors was investigated using a UV lamp (λ=365 nm, I=2.34 mW cm(-2)). A significant ratio of photocurrent to dark current--around 11,300%--was achieved.

  19. Impact of Temperature and UV Irradiation on Dynamics of NO2 Sensors Based on ZnO Nanostructures

    PubMed Central

    Pustelny, Tadeusz

    2017-01-01

    The main object of this study is the improvement of the dynamics of NO2 sensors based on ZnO nanostructures. Investigations presented in this paper showed that the combination of temperature and ultraviolet (UV) activation of the sensors can significantly decrease the sensor response and regeneration times. In comparison with the single activation method (elevated temperature or UV), these times for 1 ppm of NO2 decreased from about 10 min (or more) to less than 40 s. In addition, at the optimal conditions (200 °C and UV), sensors were very stable, were fully scalable (in the range on NO2 concentration of 1–20 ppm) and baseline drift was significantly reduced. Furthermore, in this paper, extensive studies of the influence of temperature and carrier gas (nitrogen and air) on NO2 sensing properties of the ZnO nanostructures were conducted. The NO2 sensing mechanisms of the sensors operating at elevated temperatures and under UV irradiation were also discussed. Our study showed that sensor responses to NO2 and response/regeneration times are comparable from sensor to sensor in air and nitrogen conditions, which suggests that the proposed simple technology connected with well-chosen operation conditions is repeatable. The estimated limit of detection of the sensors is within the level of ≈800 ppb in nitrogen and ≈700 ppb in air. PMID:29019924

  20. Ultrasound-assisted synthesis of nano-structured Zinc(II)-based metal-organic frameworks as precursors for the synthesis of ZnO nano-structures.

    PubMed

    Bigdeli, Fahime; Ghasempour, Hosein; Azhdari Tehrani, Alireza; Morsali, Ali; Hosseini-Monfared, Hassan

    2017-07-01

    A 3D, porous Zn(II)-based metal-organic framework {[Zn 2 (oba) 2 (4-bpmn)]·(DMF) 1.5 } n (TMU-21), (4-bpmn=N,N'-Bis-pyridin-4-ylmethylene-naphtalene-1,5-diamine, H 2 oba=4,4'-oxybis(benzoic acid)) with nano-rods morphology under ultrasonic irradiation at ambient temperature and atmospheric pressure was prepared and characterized by scanning electron microscopy. Sonication time and concentration of initial reagents effects on the size and morphology of nano-structured MOFs were studied. Also {[Zn 2 (oba) 2 (4-bpmn)] (TMU-21) and {[Zn 2 (oba) 2 (4-bpmb)] (TMU-6), 4-bpmb=N,N'-(1,4-phenylene)bis(1-(pyridin-4-yl)methanimine) were easily prepared by mechanochemical synthesis. Nanostructures of Zinc(II) oxide were obtained by calcination of these compounds and their de-solvated analogue as activated MOFs, at 550°C under air atmosphere. As a result of that, different Nanostructures of Zinc(II) oxide were obtained. The ZnO nanoparticles were characterized by powder X-ray diffraction (XRD), scanning electron microscopy (SEM) and FT-IR spectroscopy. Copyright © 2016 Elsevier B.V. All rights reserved.

  1. Room-temperature sensitivity to NO2 exposure of electrochemically-deposited nanostructured ZnO layers

    NASA Astrophysics Data System (ADS)

    Lovchinov, K.; Petrov, M.; Ganchev, M.; Georgieva, V.; Nichev, H.; Georgieva, B.; Dimova-Malinovska, D.

    2014-05-01

    This paper reports studies on the sensitivity of ZnO layers to NO2 exposure. ZnO layers were fabricated by electrochemical deposition on the surface of a quartz crystal microbalance (QCM) with Au electrodes. The sensitivity was estimated using the frequency-time characteristics of the QCM. For this purpose, the resonance frequency shift was measured. The sorption process was investigated in a NO2 gas flow. The change in the resonance frequency, f of the QCM as a function of the loaded mass of NO2 was followed for a NO2 concentration of 500 ppm. Under gas exposure, the frequency decreased and reached saturation in five min. A frequency shift of 38 Hz was measured and a mass loading of 8.39 ng was calculated. The resonance frequency showed a very good recovery within two minutes after the NO2 flow was switched off. The results demonstrate that the electrodeposited nanostructured ZnO layers have a potential for application as NO2 gas sensors.

  2. Enhanced photoluminescence and Raman properties of Al-Doped ZnO nanostructures prepared using thermal chemical vapor deposition of methanol assisted with heated brass.

    PubMed

    Thandavan, Tamil Many K; Gani, Siti Meriam Abdul; San Wong, Chiow; Md Nor, Roslan

    2015-01-01

    Vapor phase transport (VPT) assisted by mixture of methanol and acetone via thermal evaporation of brass (CuZn) was used to prepare un-doped and Al-doped zinc oxide (ZnO) nanostructures (NSs). The structure and morphology were characterized by field emission scanning electron microscopy (FESEM) and x-ray diffraction (XRD). Photoluminescence (PL) properties of un-doped and Al-doped ZnO showed significant changes in the optical properties providing evidence for several types of defects such as zinc interstitials (Zni), oxygen interstitials (Oi), zinc vacancy (Vzn), singly charged zinc vacancy (VZn-), oxygen vacancy (Vo), singly charged oxygen vacancy (Vo+) and oxygen anti-site defects (OZn) in the grown NSs. The Al-doped ZnO NSs have exhibited shifted PL peaks at near band edge (NBE) and red luminescence compared to the un-doped ZnO. The Raman scattering results provided evidence of Al doping into the ZnO NSs due to peak shift from 145 cm-1 to an anomalous peak at 138 cm-1. Presence of enhanced Raman signal at around 274 and 743 cm-1 further confirmed Al in ZnO NSs. The enhanced D and G band in all Al-doped ZnO NSs shows possible functionalization and doping process in ZnO NSs.

  3. Studies on visible light photocatalytic and antibacterial activities of nanostructured cobalt doped ZnO thin films prepared by sol-gel spin coating method.

    PubMed

    Poongodi, G; Anandan, P; Kumar, R Mohan; Jayavel, R

    2015-09-05

    Nanostructured cobalt doped ZnO thin films were deposited on glass substrate by sol-gel spin coating technique and characterized by X-ray diffraction, X-ray photoelectron spectroscopy, field-emission scanning electron microscopy, energy-dispersive X-ray spectroscopy and UV-Vis spectroscopy. The XRD results showed that the thin films were well crystalline with hexagonal wurtzite structure. The results of EDAX and XPS revealed that Co was doped into ZnO structure. FESEM images revealed that the films possess granular morphology without any crack and confirm that Co doping decreases the grain size. UV-Vis transmission spectra show that the substitution of Co in ZnO leads to band gap narrowing. The Co doped ZnO films were found to exhibit improved photocatalytic activity for the degradation of methylene blue dye under visible light in comparison with the undoped ZnO film. The decrease in grain size and extending light absorption towards the visible region by Co doping in ZnO film contribute equally to the improved photocatalytic activity. The bactericidal efficiency of Co doped ZnO films were investigated against a Gram negative (Escherichia coli) and a Gram positive (Staphylococcus aureus) bacteria. The optical density (OD) measurement showed better bactericidal activity at higher level of Co doping in ZnO. Copyright © 2015 Elsevier B.V. All rights reserved.

  4. Hydrodynamic fabrication of structurally gradient ZnO nanorods.

    PubMed

    Kim, Hyung Min; Youn, Jae Ryoun; Song, Young Seok

    2016-02-26

    We studied a new approach where structurally gradient nanostructures were fabricated by means of hydrodynamics. Zinc oxide (ZnO) nanorods were synthesized in a drag-driven rotational flow in a controlled manner. The structural characteristics of nanorods such as orientation and diameter were determined by momentum and mass transfer at the substrate surface. The nucleation of ZnO was induced by shear stress which plays a key role in determining the orientation of ZnO nanorods. The nucleation and growth of such nanostructures were modeled theoretically and analyzed numerically to understand the underlying physics of the fabrication of nanostructures controlled by hydrodynamics. The findings demonstrated that the precise control of momentum and mass transfer enabled the formation of ZnO nanorods with a structural gradient in diameter and orientation.

  5. Shape-Dependent Photocatalytic Activity of Hydrothermally Synthesized Cadmium Sulfide Nanostructures.

    PubMed

    Kundu, Joyjit; Khilari, Santimoy; Pradhan, Debabrata

    2017-03-22

    The effective surface area of the nanostructured materials is known to play a prime role in catalysis. Here we demonstrate that the shape of the nanostructured materials plays an equally important role in their catalytic activity. Hierarchical CdS microstructures with different morphologies such as microspheres assembled of nanoplates, nanorods, nanoparticles, and nanobelts are synthesized using a simple hydrothermal method by tuning the volume ratio of solvents, i.e., water or ethylenediamine (en). With an optimum solvent ratio of 3:1 water:en, the roles of other synthesis parameters such as precursor's ratio, temperature, and precursor combinations are also explored and reported here. Four selected CdS microstructures are used as photocatalysts for the degradation of methylene blue and photoelectrochemical water splitting for hydrogen generation. In spite of smaller effective surface area of CdS nanoneedles/nanorods than that of CdS nanowires network, the former exhibits higher catalytic activity under visible light irradiation which is ascribed to the reduced charge recombination as confirmed from the photoluminescence study.

  6. Enhanced room temperature ferromagnetism in electrodeposited Co-doped ZnO nanostructured thin films by controlling the oxygen vacancy defects

    SciTech Connect

    Simimol, A.; Department of Physics, National Institute of Technology Calicut, Calicut 673601; Anappara, Aji A.

    We report the growth of un-doped and cobalt doped ZnO nanostructures fabricated on FTO coated glass substrates using electrodeposition method. A detailed study on the effects of dopant concentration on morphology, structural, optical, and magnetic properties of the ZnO nanostructures has been carried out systematically by varying the Co concentration (c.{sub Co}) from 0.01 to 1 mM. For c.{sub Co }≤ 0.2 mM, h-wurtzite phase with no secondary phases of Co were present in the ZnO nanostructures. For c.{sub Co} ≤ 0.2 mM, the photoluminescence spectra exhibited a decrease in the intensity of ultraviolet emission as well as band-gap narrowing with an increase in dopantmore » concentration. All the doped samples displayed a broad emission in the visible range and its intensity increased with an increase in Co concentration. It was found that the defect centers such as oxygen vacancies and zinc interstitials were the source of the visible emission. The X-ray photoelectron spectroscopy studies revealed, Co was primarily in the divalent state, replacing the Zn ion inside the tetrahedral crystal site of ZnO without forming any cluster or secondary phases of Co. The un-doped ZnO nanorods exhibited diamagnetic behavior and it remained up to a c.{sub Co} of 0.05 mM, while for c.{sub Co }> 0.05 mM, the ZnO nanostructures exhibited ferromagnetic behavior at room temperature. The coercivity increased to 695 G for 0.2 mM Co-doped sample and then it decreased for c.{sub Co }> 0.2 mM. Our results illustrate that up to a threshold concentration of 0.2 mM, the strong ferromagnetism is due to the oxygen vacancy defects centers, which exist in the Co-doped ZnO nanostructures. The origin of strong ferromagnetism at room temperature in Co-doped ZnO nanostructures is attributed to the s-d exchange interaction between the localized spin moments resulting from the oxygen vacancies and d electrons of Co{sup 2+} ions. Our findings provide a new insight for

  7. Influence Al doped ZnO nanostructure on structural and optical properties

    SciTech Connect

    Ramelan, Ari Handono, E-mail: aramelan@mipa.uns.ac.id; Wahyuningsih, Sayekti; Chasanah, Uswatul

    2016-04-19

    The preparation of Al-doped ZnO (AZO) thin films prepared by the spin-coating method was reported. Preparation of AZO was conducted by annealing treatment at a temperature of 700°C. While the spin-coating process of AZO thin films were done at 2000 and 3000 rpm respectively. The structural properties of ZnO were determined by X- ray diffraction (XRD) analysis. ZnOnanostructure was formed after annealed at atemperature of 400°C.The morphology of ZnO was determined by Scanning Electron Microscopy (SEM) showed the irregular morphology about 30-50µm in size. Al doped on ZnO influenced the optical properties of those material. Increasing Al contain on ZnO causemore » of shifting to the lower wavelength. The optical properties of the ZnO as well as AZO films showed that higher reflectance on the ultraviolet region so those materials were used as anti-reflecting agent.Al addition significantly enhance the optical transparency and induce the blue-shift in optical bandgap of ZnO films.« less

  8. Structural, magnetic and optical properties of ZnO nanostructures converted from ZnS nanoparticles

    SciTech Connect

    Patel, Prayas Chandra; Ghosh, Surajit; Srivastava, P.C., E-mail: pcsrivastava50@gmail.com

    Graphical abstract: The phase conversion of ZnS to highly crystalline hexagonal ZnO was done by heat treatment. - Highlights: • Phase change of cubic ZnS to hexagonal ZnO via heat treatment. • Band gap was found to decrease with increasing calcinations temperature. • ZnO samples have higher magnetic moment than ZnS. • Blocking Temperature of the samples is well above room temperature. • Maximum negative%MR with saturation value ∼38% was found for sample calcined at 600° C. - Abstract: The present work concentrates on the synthesis of cubic ZnS and hexagonal ZnO semiconducting nanoparticle from same precursor via co-precipitation method.more » The phase conversion of ZnS to highly crystalline hexagonal ZnO was done by heat treatment. From the analysis of influence of calcination temperature on the structural, optical and vibrational properties of the samples, an optimum temperature was found for the total conversion of ZnS nanoparticles to ZnO. Role of quantum confinement due to finite size is evident from the blue shift of the fundamental absorption in UV–vis spectra only in the ZnS nanoparticles. The semiconducting nature of the prepared samples is confirmed from the UV–vis, PL study and transport study. From the magnetic and transport studies, pure ZnO phase was found to be more prone to magnetic field.« less

  9. Correlation between reflectance and photoluminescent properties of al-rich ZnO nano-structures

    NASA Astrophysics Data System (ADS)

    Khan, Firoz; Baek, Seong-Ho; Ahmad, Nafis; Lee, Gun Hee; Seo, Tae Hoon; Suh, Eun-kyung; Kim, Jae Hyun

    2015-05-01

    Al rich zinc oxide nano-structured films were synthesized using spin coating sol-gel technique. The films were annealed in oxygen ambient in the temperature range of 200-700 °C. The structural, optical, and photoluminescence (PL) properties of the films were studied at various annealing temperatures using X-ray diffraction spectroscopy, field emission scanning electron microscopy, photoluminescence emission spectra measurement, and Raman and UV-Vis spectroscopy. The optical band gap was found to decrease with the increase of the annealing temperature following the Gauss Amp function due to the confinement of the exciton. The PL peak intensity in the near band region (INBE) was found to increase with the increase of the annealing temperature up to 600 °C, then to decrease fast to a lower value for the annealing temperature of 700 °C due to crystalline quality. The Raman peak of E2 (low) was red shifted from 118 cm-1 to 126 cm-1 with the increase of the annealing temperature. The intensity of the second order phonon (TA+LO) at 674 cm-1 was found to decrease with the increase of the annealing temperature. The normalized values of the reflectance and the PL intensity in the NBE region were highest for the annealing temperature of 600 °C. A special correlation was found between the reflectance at λ = 1000 nm and the normalized PL intensity in the green region due to scattering due to presence of grains.

  10. Microstructural and optical properties of Mn doped NiO nanostructures synthesized via sol-gel method

    NASA Astrophysics Data System (ADS)

    Shah, Shamim H.; Khan, Wasi; Naseem, Swaleha; Husain, Shahid; Nadeem, M.

    2018-04-01

    Undoped and Mn(0, 5%, 10% and 15%) doped NiO nanostructures were synthesized by sol-gel method. Structure, morphology and optical properties were investigated through XRD, FTIR, SEM/EDS and UV-visible absorption spectroscopy techniques. XRD data analysis reveals the single phase nature with cubic crystal symmetry of the samples and the average crystallite size decreases with the doping of Mn ions upto 10%. FTIR spectra further confirmed the purity and composition of the synthesized samples. The non-spherical shape of the nanostructures was observed from SEM micrographs and gain size of the nanostructures reduces with Mn doping in NiO, whereas agglomeration increases in doped sample. Optical band gap was estimated using Tauc'srelation and found to increase on incorporation of Mn upto 10% in host lattice and then decreases for further doping.

  11. High UV light performance for the degradation of Rhodamine B dye by synthesized Bi2S3ZnO nanocomposite

    NASA Astrophysics Data System (ADS)

    Sangareswari, M.; Meenakshi Sundaram, M.

    2017-05-01

    Heterogeneous photocatalytic degradation of organics in water and wastewater by large band gap semiconductors has offered an attractive alternative for environmental remediation. Zinc oxide is a very fast and efficient catalyst because of its wide band gap and large exciton binding energy. In this study, an efficient Bi2S3ZnO was synthesized by sonochemical method. The obtained product was further characterized by TEM, SEM, XRD, FT-IR and UV-DRS analysis. Scanning electron microscopy images revealed that Bi2S3ZnO has flower-like structure. The synthesized flower-like Bi2S3ZnO nanocomposites were more efficient than commercial ZnO for the degradation of organic contaminants under UV light irradiation. The prepared material shows enhanced photocatalytic activity on Rhodamine B dye solution under UV light irradiation. The percentage removal of dye was calculated by UV-Vis spectrophotometer. In addition, Bi2S3ZnO showed tremendous photocatalytic stability after seven cycles under UV light irradiation. A possible mechanism for the photocatalytic oxidative degradation was also discussed. It is concluded that the Bi2S3ZnO nanocomposite acts as an excellent photocatalyst for the decomposition of RhB and it could be a potential material for essential wastewater treatment.

  12. Synthesized zinc peroxide nanoparticles (ZnO2-NPs): a novel antimicrobial, anti-elastase, anti-keratinase, and anti-inflammatory approach toward polymicrobial burn wounds

    PubMed Central

    El-Zawawy, Nessma Ahmed; Fareed, Mervat F; Bedaiwy, Mohamed Yaser

    2017-01-01

    Increasing of multidrug resistance (MDR) remains an intractable challenge for burn patients. Innovative nanomaterials are also in high demand for the development of new antimicrobial biomaterials that inevitably have opened new therapeutic horizons in medical approaches and lead to many efforts for synthesizing new metal oxide nanoparticles (NPs) for better control of the MDR associated with the polymicrobial burn wounds. Recently, it seems that metal oxides can truly be considered as highly efficient inorganic agents with antimicrobial properties. In this study, zinc peroxide NPs (ZnO2-NPs) were synthesized using the co-precipitation method. Synthesized ZnO2-NPs were characterized by X-ray diffraction, Fourier transformed infrared, transmission electron microscopy, thermogravimetric analysis, differential scanning calorimetry, and ultraviolet-visible spectroscopy. The characterization techniques revealed synthesis of the pure phase of non-agglomerated ZnO2-NPs having sizes in the range of 15–25 nm with a transition temperature of 211°C. Antimicrobial activity of ZnO2-NPs was determined against MDR Pseudomonas aeruginosa (PA) and Aspergillus niger (AN) strains isolated from burn wound infections. Both strains, PA6 and AN4, were found to be more susceptible strains to ZnO2-NPs. In addition, a significant decrease in elastase and keratinase activities was recorded with increased concentrations of ZnO2-NPs until 200 µg/mL. ZnO2-NPs revealed a significant anti-inflammatory activity against PA6 and AN4 strains as demonstrated by membrane stabilization, albumin denaturation, and proteinase inhibition. Moreover, the results of in vivo histopathology assessment confirmed the potential role of ZnO2-NPs in the improvement of skin wound healing in the experimental animal models. Clearly, the synthesized ZnO2-NPs have demonstrated a competitive capability as antimicrobial, anti-elastase, anti-keratinase, and anti-inflammatory candidates, suggesting that the ZnO2-NPs are

  13. Synthesized zinc peroxide nanoparticles (ZnO2-NPs): a novel antimicrobial, anti-elastase, anti-keratinase, and anti-inflammatory approach toward polymicrobial burn wounds.

    PubMed

    Ali, Sameh Samir; Morsy, Reda; El-Zawawy, Nessma Ahmed; Fareed, Mervat F; Bedaiwy, Mohamed Yaser

    2017-01-01

    Increasing of multidrug resistance (MDR) remains an intractable challenge for burn patients. Innovative nanomaterials are also in high demand for the development of new antimicrobial biomaterials that inevitably have opened new therapeutic horizons in medical approaches and lead to many efforts for synthesizing new metal oxide nanoparticles (NPs) for better control of the MDR associated with the polymicrobial burn wounds. Recently, it seems that metal oxides can truly be considered as highly efficient inorganic agents with antimicrobial properties. In this study, zinc peroxide NPs (ZnO 2 -NPs) were synthesized using the co-precipitation method. Synthesized ZnO 2 -NPs were characterized by X-ray diffraction, Fourier transformed infrared, transmission electron microscopy, thermogravimetric analysis, differential scanning calorimetry, and ultraviolet-visible spectroscopy. The characterization techniques revealed synthesis of the pure phase of non-agglomerated ZnO 2 -NPs having sizes in the range of 15-25 nm with a transition temperature of 211°C. Antimicrobial activity of ZnO 2 -NPs was determined against MDR Pseudomonas aeruginosa (PA) and Aspergillus niger (AN) strains isolated from burn wound infections. Both strains, PA6 and AN4, were found to be more susceptible strains to ZnO 2 -NPs. In addition, a significant decrease in elastase and keratinase activities was recorded with increased concentrations of ZnO 2 -NPs until 200 µg/mL. ZnO 2 -NPs revealed a significant anti-inflammatory activity against PA6 and AN4 strains as demonstrated by membrane stabilization, albumin denaturation, and proteinase inhibition. Moreover, the results of in vivo histopathology assessment confirmed the potential role of ZnO 2 -NPs in the improvement of skin wound healing in the experimental animal models. Clearly, the synthesized ZnO 2 -NPs have demonstrated a competitive capability as antimicrobial, anti-elastase, anti-keratinase, and anti-inflammatory candidates, suggesting that the

  14. Plasmonic enhanced optical characteristics of Ag nanostructured ZnO thin films

    NASA Astrophysics Data System (ADS)

    Sarkar, Arijit; Gogurla, Narendar; Shivakiran Bhaktha, B. N.; Ray, Samit K.

    2016-04-01

    We have demonstrated the enhanced photoluminescence and photoconducting characteristics of plasmonic Ag-ZnO films due to the light scattering effect from Ag nanoislands. Ag nanoislands have been prepared on ITO-coated glass substrates by thermal evaporation followed by annealing. Plasmonic Ag-ZnO films have been fabricated by depositing ZnO over Ag nanoislands by sol-gel process. The band-edge emission of ZnO is enhanced for 170 nm sized Ag nanoislands in ZnO as compared to pure ZnO. The defect emission is also found to be quenched simultaneously for plasmonic Ag-ZnO films. The enhancement and quenching of photoluminescence at different wavelengths for Ag-ZnO films can be well understood from the localized surface plasmon resonance of Ag nanoislands. The Ag-ZnO M-S-M photoconductor device showed a tenfold increment in photocurrent and faster photoresponse as compared to the control ZnO device. The enhancement in photoresponse of the device is due to the increased photon absorption in ZnO films via scattering of the incident illumination.

  15. On the origin of blue emission from ZnO quantum dots synthesized by a sol-gel route

    NASA Astrophysics Data System (ADS)

    Han, Li-Li; Cui, Lan; Wang, Wei-Hua; Wang, Jiang-Long; Du, Xi-Wen

    2012-06-01

    ZnO quantum dots (QDs) with blue emission were synthesized by a sol-gel method. A series of control experiments were conducted to explore the origin of the blue emission. It is found that the blue emission arises from neither the quantum confinement nor intermediate products, and it can be achieved only in the presence of Li+ cations and excessive OH- anions. Moreover, the long decay time of the blue emission suggests a defect-related de-excitation process. On the basis of the experimental and calculation results, possible de-excitation paths for light emission were discussed, and the origin of the blue emission was determined as the electron transition from the conduction band to interstitial oxygen defects. Excessive OH- anions are responsible for the formation of interstitial oxygen defects, and Li+ ions can stabilize the defects by substituting for Zn atoms. Besides, Li+ ions can block the growth of ZnO QDs, broaden their band gap and cause a blue shift of the blue emission.

  16. Significant enhancement in thermoelectric performance of nanostructured higher manganese silicides synthesized employing a melt spinning technique.

    PubMed

    Muthiah, Saravanan; Singh, R C; Pathak, B D; Avasthi, Piyush Kumar; Kumar, Rishikesh; Kumar, Anil; Srivastava, A K; Dhar, Ajay

    2018-01-25

    The limited thermoelectric performance of p-type Higher Manganese Silicides (HMS) in terms of their low figure-of-merit (ZT), which is far below unity, is the main bottle-neck for realising an efficient HMS based thermoelectric generator, which has been recognized as the most promising material for harnessing waste-heat in the mid-temperature range, owing to its thermal stability, earth-abundant and environmentally friendly nature of its constituent elements. We report a significant enhancement in the thermoelectric performance of nanostructured HMS synthesized using rapid solidification by optimizing the cooling rates during melt-spinning followed by spark plasma sintering of the resulting melt-spun ribbons. By employing this experimental strategy, an unprecedented ZT ∼ 0.82 at 800 K was realized in spark plasma sintered 5 at% Al-doped MnSi 1.73 HMS, melt spun at an optimized high cooling rate of ∼2 × 10 7 K s -1 . This enhancement in ZT represents a ∼25% increase over the best reported values thus far for HMS and primarily originates from a nano-crystalline microstructure consisting of a HMS matrix (20-40 nm) with excess Si (3-9 nm) uniformly distributed in it. This nanostructure, resulting from the high cooling rates employed during the melt-spinning of HMS, introduces a high density of nano-crystallite boundaries in a wide spectrum of nano-scale dimensions, which scatter the low-to-mid-wavelength heat-carrying phonons. This abundant phonon scattering results in a significantly reduced thermal conductivity of ∼1.5 W m -1 K -1 at 800 K, which primarily contributes to the enhancement in ZT.

  17. Optical and Magnetic Properties of ZnO Nanoparticles Doped with Co, Ni and Mn and Synthesized at Low Temperature.

    PubMed

    Hancock, Jared M; Rankin, William M; Hammad, Talaat M; Salem, Jamil S; Chesnel, Karine; Harrison, Roger G

    2015-05-01

    Zinc oxide nanomaterials were synthesized with small amounts of magnetic ions to create dilute magnetic semiconductors (DMS), by using a low temperature sol-gel method. Conditions were controlled such that a range of amounts of Co, Ni and Mn were incorporated. The incorporation could be tracked by color changes in the powders to blue for Co, green for Ni and yellow for Mn. XRD measurements showed the ZnO has the wurtzite structure with crystallites 8-12 nm in diameter. Nanoparticles were observed by SEM and TEM and TEM showed that the lattice fringes of different nanoparticles align. Nanoparticle alignment was disrupted when high concentrations of metal dopants were incorporated. Magnetic measurements showed a change in behavior from diamagnetic to paramagnetic with increasing concentration of metal dopants.

  18. Enhanced super-hydrophobic and switching behavior of ZnO nanostructured surfaces prepared by simple solution--immersion successive ionic layer adsorption and reaction process.

    PubMed

    Suresh Kumar, P; Sundaramurthy, J; Mangalaraj, D; Nataraj, D; Rajarathnam, D; Srinivasan, M P

    2011-11-01

    A simple and cost-effective successive ionic layer adsorption and reaction (SILAR) method was adopted to fabricate hydrophobic ZnO nanostructured surfaces on transparent indium-tin oxide (ITO), glass and polyethylene terephthalate (PET) substrates. ZnO films deposited on different substrates show hierarchical structures like spindle, flower and spherical shape with diameters ranging from 30 to 300 nm. The photo-induced switching behaviors of ZnO film surfaces between hydrophobic and hydrophilic states were examined by water contact angle and X-ray photoelectron spectroscopy (XPS) analysis. ZnO nanostructured films had contact angles of ~140° and 160°±2 on glass and PET substrates, respectively, exhibiting hydrophobic behavior without any surface modification or treatment. Upon exposure to ultraviolet (UV) illumination, the films showed hydrophilic behavior (contact angle: 15°±2), which upon low thermal stimuli revert back to its original hydrophobic nature. Such reversible and repeatable switching behaviors were observed upon cyclical exposure to ultraviolet radiation. These biomimetic ZnO surfaces exhibit good anti-reflective properties with lower reflectance of 9% for PET substrates. Thus, the present work is significant in terms of its potential application in switching devices, solar coatings and self-cleaning smart windows. Copyright © 2011 Elsevier Inc. All rights reserved.

  19. Accelerated Thermal-Aging-Induced Degradation of Organometal Triiodide Perovskite on ZnO Nanostructures and Its Effect on Hybrid Photovoltaic Devices.

    PubMed

    Kumar, S; Dhar, A

    2016-07-20

    Organometal halide perovskite materials are presently some of the pacesetters for light harvesting in hybrid photovoltaic devices because of their excellent inherent electrical and optical properties. However, long-term durability of such perovskite materials remains a major bottleneck for their commercialization especially in countries with hot and humid climatic conditions, thus violating the international standards for photovoltaic technology. Albeit, TiO2 as an electron-transport layer has been well investigated for perovskite solar cells; the high-temperature processing makes it unsuitable for low-cost and large-scale roll-to-roll production of flexible photovoltaic devices. Herein, we have chosen low-temperature (<150 °C)-processable nanostructured ZnO as the electron-selective layer and used a two-step method for sensitizing ZnO nanorods with methylammonium lead iodide (MAPbI3) perovskite, which is viable for flexible photovoltaic devices. We have also elaborately addressed the effect of the annealing duration on the conversion of a precursor solution into the required perovskite phase on ZnO nanostructures. The investigations show that the presence of ZnO nanostructures accelerates the rate of degradation of MAPbI3 films under ambient annealing and thus requires proper optimization. The role of ZnO in enhancing the degradation kinetics of the perovskite layer has been investigated by X-ray photoelectron spectroscopy and a buffer layer passivation technique. The effect of the annealing duration of the MAPbI3 perovskite on the optical, morphological, and compositional behavior has been closely studied and correlated with the photovoltaic efficiency. The study captures the degradation behavior of the commercially interesting MAPbI3 perovskite on a ZnO electron-transport layer and thus can provide insight for developing alternative families of perovskite material with better thermal and environmental stability for application in low-cost flexible photovoltaic

  20. Performance and stability analysis of curcumin dye as a photo sensitizer used in nanostructured ZnO based DSSC

    NASA Astrophysics Data System (ADS)

    Sinha, D.; De, D.; Ayaz, A.

    2018-03-01

    Environmental friendly natural dye curcumin extracted from low-cost Curcumina longa stem is used as a photo-sensitizer for the fabrication of ZnO-based dye-sensitized solar cells (DSSC). Nanostructured ZnO is fabricated on a transparent conducting glass (TCO), using a cost-effective chemical bath deposition technique. Scanning electron microscopic images show hexagonal patterned ZnO nano-towers decorated with several nanosteps. The average length of ZnO nano-tower is 5 μm and diameter is 1.2 μm. The UV-Vis spectroscopic study of the curcumin dye is used to understand the light absorption behavior as well as band gap energy of the extracted natural dye. The dye shows wider absorption band-groups over 350-470 nm and 500-600 nm with two peaks positioned at 425 nm and 525 nm. The optical band gap energy and energy band position of the dye is derived which supports its stability and high electron affinity that makes it suitable for light harvesting and effortless electron transfer from dye to the semiconductor or interface between them. FTIR spectrum of curcumin dye-sensitized ZnO-based DSSC shows the presence of anchoring groups and colouring constitutes. The I-V and P-V curves of the fabricated DSSC are measured under simulated light (100 mW/cm2). The highest visible light to electric conversion efficiency of 0.266% (using ITO) and 0.33% (using FTO) is achieved from the curcumin dye-sensitized cell.

  1. Pulsed laser deposited hexagonal wurzite ZnO thin-film nanostructures/nanotextures for nanophotonics applications

    NASA Astrophysics Data System (ADS)

    John Chelliah, Cyril Robinson Azariah; Swaminathan, Rajesh

    2018-01-01

    The high-quality and transparent thin-film zinc oxide (ZnO) nanostructures/nanotextures deposited on glass and silicon substrates using pulsed laser deposition (PLD) technique are reported. A solid-state, Nd-YAG laser was used for the PLD process. The films were deposited (i) at room temperature of 25°C (as deposited), (ii) at 150°C, (iii) at 300°C, (iv) at 450°C, and (v) at 600°C and annealed in the vacuum chamber. The depositions were also carried out at different laser repetition rates such as 10 and 5 Hz. UV spectroscopy and photoluminescence (PL) spectroscopy were carried out for optical studies. X-ray diffraction studies were carried out for all samples and analyzed the effects of the laser repetition rate, deposition, and annealing temperatures on the structural properties. Field-emission scanning electron microscope images are recorded for the best-structured samples. The electrical parameters were calibrated using the Hall effect measurement system and the IV characterization was performed using a CHI Electrochemical workstation. The deposition temperature has a significant effect on the microstrain and dislocation density of the ZnO thin film and optical phenomena with various electrical parameters, including the electron mobility, conductivity, and magnetoresistance. These promising results are suitable conditions for nanophotonics applications.

  2. Thermal replacement reaction: a novel route for synthesizing eco-friendly ZnO@γ-In2Se3 hetero-nanostructures by replacing cadmium with indium and their photoelectrochemical and photocatalytic performances.

    PubMed

    Zhang, Zhuo; Choi, Mingi; Baek, Minki; Yong, Kijung

    2015-05-21

    A novel route called thermal replacement reaction was demonstrated for synthesizing eco-friendly ZnO@γ-In2Se3 hetero-structural nanowires on FTO glass by replacing the element cadmium with indium for the first time. The indium layer was coated on the surface of the ZnO nanowires beforehand, then CdSe quantum dots were deposited onto the coated indium layer, and finally the CdSe quantum dots were converted to γ-In2Se3 quantum dots by annealing under vacuum at 350 °C for one hour. The prepared ZnO@γ-In2Se3 hetero-nanostructures exhibit stable photoelectrochemical properties that can be ascribed to the protection of the In2O3 layer between the ZnO nanowire and γ-In2Se3 quantum dots and better photocatalytic performance in the wide wavelength region from 400 nm to nearly 750 nm. This strategy for preparing the ZnO@γ-In2Se3 hetero-nanostructures not only enriches our understanding of the single replacement reaction where the active element cadmium can be replaced with indium, but also opens a new way for the in situ conversion of cadmium-based to eco-friendly indium-based nano-devices.

  3. Thermal replacement reaction: a novel route for synthesizing eco-friendly ZnO@γ-In2Se3 hetero-nanostructures by replacing cadmium with indium and their photoelectrochemical and photocatalytic performances

    NASA Astrophysics Data System (ADS)

    Zhang, Zhuo; Choi, Mingi; Baek, Minki; Yong, Kijung

    2015-05-01

    A novel route called thermal replacement reaction was demonstrated for synthesizing eco-friendly ZnO@γ-In2Se3 hetero-structural nanowires on FTO glass by replacing the element cadmium with indium for the first time. The indium layer was coated on the surface of the ZnO nanowires beforehand, then CdSe quantum dots were deposited onto the coated indium layer, and finally the CdSe quantum dots were converted to γ-In2Se3 quantum dots by annealing under vacuum at 350 °C for one hour. The prepared ZnO@γ-In2Se3 hetero-nanostructures exhibit stable photoelectrochemical properties that can be ascribed to the protection of the In2O3 layer between the ZnO nanowire and γ-In2Se3 quantum dots and better photocatalytic performance in the wide wavelength region from 400 nm to nearly 750 nm. This strategy for preparing the ZnO@γ-In2Se3 hetero-nanostructures not only enriches our understanding of the single replacement reaction where the active element cadmium can be replaced with indium, but also opens a new way for the in situ conversion of cadmium-based to eco-friendly indium-based nano-devices.

  4. The Influence of Shape on the Output Potential of ZnO Nanostructures: Sensitivity to Parallel versus Perpendicular Forces.

    PubMed

    Cardoso, José; Oliveira, Filipe F; Proenca, Mariana P; Ventura, João

    2018-05-22

    With the consistent shrinking of devices, micro-systems are, nowadays, widely used in areas such as biomedics, electronics, automobiles, and measurement devices. As devices shrunk, so too did their energy consumptions, opening the way for the use of nanogenerators (NGs) as power sources. In particular, to harvest energy from an object's motion (mechanical vibrations, torsional forces, or pressure), present NGs are mainly composed of piezoelectric materials in which, upon an applied compressive or strain force, an electrical field is produced that can be used to power a device. The focus of this work is to simulate the piezoelectric effect in different ZnO nanostructures to optimize the output potential generated by a nanodevice. In these simulations, cylindrical nanowires, nanomushrooms, and nanotrees were created, and the influence of the nanostructures' shape on the output potential was studied as a function of applied parallel and perpendicular forces. The obtained results demonstrated that the output potential is linearly proportional to the applied force and that perpendicular forces are more efficient in all structures. However, nanotrees were found to have an increased sensitivity to parallel applied forces, which resulted in a large enhancement of the output efficiency. These results could then open a new path to increase the efficiency of piezoelectric nanogenerators.

  5. ZnO Nanostructure Templates as a Cost-Efficient Mass-Producible Route for the Development of Cellular Networks

    PubMed Central

    Makarona, Eleni; Peter, Beatrix; Szekacs, Inna; Tsamis, Christos; Horvath, Robert

    2016-01-01

    The development of artificial surfaces which can regulate or trigger specific functions of living cells, and which are capable of inducing in vivo-like cell behaviors under in vitro conditions has been a long-sought goal over the past twenty years. In this work, an alternative, facile and cost-efficient method for mass-producible cellular templates is presented. The proposed methodology consists of a cost-efficient, two-step, all-wet technique capable of producing ZnO-based nanostructures on predefined patterns on a variety of substrates. ZnO—apart from the fact that it is a biocompatible material—was chosen because of its multifunctional nature which has rendered it a versatile material employed in a wide range of applications. Si, Si3N4, emulated microelectrode arrays and conventional glass cover slips were patterned at the micrometer scale and the patterns were filled with ZnO nanostructures. Using HeLa cells, we demonstrated that the fabricated nanotopographical features could promote guided cellular adhesion on the pre-defined micron-scale patterns only through nanomechanical cues without the need for further surface activation or modification. The basic steps of the micro/nanofabrication are presented and the results from the cell adhesion experiments are discussed, showing the potential of the suggested methodology for creating low-cost templates for engineered cellular networks. PMID:28773382

  6. Nanostructured gold microelectrodes for SERS and EIS measurements by incorporating ZnO nanorod growth with electroplating

    PubMed Central

    Zong, Xianli; Zhu, Rong; Guo, Xiaoliang

    2015-01-01

    In this paper, a fine gold nanostructure synthesized on selective planar microelectrodes in micro-chip is realized by using an advanced hybrid fabrication approach incorporating growth of nanorods (NRs) with gold electroplating. By this developed nanostructure, integration of in-situ surface-enhanced Raman spectroscopy (SERS) detection with electrochemical impedance spectroscopy (EIS) measurement for label-free, nondestructive, real-time and rapid monitoring on a single cell has been achieved. Moreover, parameters of Au nanostructures such as size of nanoholes/nanogaps can be controllably adjusted in the fabrication. We have demonstrated a SERS enhancement factor of up to ~2.24 × 106 and double-layer impedance decrease ratio of 90% ~ 95% at low frequency range below 200 kHz by using nanostructured microelectrodes. SERS detection and in-situ EIS measurement of a trapped single cell by using planar microelectrodes are realized to demonstrate the compatibility, multi-functions, high-sensitivity and simplicity of the micro-chip system. This dual function platform integrating SERS and EIS is of great significance in biological, biochemical and biomedical applications. PMID:26558325

  7. Structural and spectroscopic study of mechanically synthesized SnO{sub 2} nanostructures

    SciTech Connect

    Vij, Ankush, E-mail: vij-anx@yahoo.com; Kumar, Ravi; Presently at Beant College of Engineering and Technology, Gurdaspur-143521

    2016-05-23

    We report the single step synthesis of SnO{sub 2} nanostructures using high energy mechanical attrition method. X-ray diffraction (XRD) pattern reveals the single phase rutile structure with appreciable broadening of diffraction peaks, which is a signature of nanostructure formation. The average crystallite size of SnO{sub 2} nanostructures has been calculated to be ~15 nm. The micro-Raman study reveals the shifting of A{sub 1g} Raman mode towards lower wave number, which is correlated with the nanostructure formation.

  8. Structural and spectroscopic study of mechanically synthesized SnO2 nanostructures

    NASA Astrophysics Data System (ADS)

    Vij, Ankush; Kumar, Ravi

    2016-05-01

    We report the single step synthesis of SnO2 nanostructures using high energy mechanical attrition method. X-ray diffraction (XRD) pattern reveals the single phase rutile structure with appreciable broadening of diffraction peaks, which is a signature of nanostructure formation. The average crystallite size of SnO2 nanostructures has been calculated to be ~15 nm. The micro-Raman study reveals the shifting of A1g Raman mode towards lower wave number, which is correlated with the nanostructure formation.

  9. Morphology and phase transformations of tin oxide nanostructures synthesized by the hydrothermal method in the presence of dicarboxylic acids

    NASA Astrophysics Data System (ADS)

    Zima, Tatyana.; Bataev, Ivan

    2016-11-01

    A new approach to the synthesis of non-stoichiometric tin oxide structures with different morphologies and the phase compositions has been evaluated. The nanostructures were synthesized by hydrothermal treatment of the mixtures of dicarboxylic acids ― aminoterephthalic or oxalic ― with nanocrystalline SnO2 powder, which was obtained via the sol-gel technology. The products were characterized by Raman and IR spectroscopy, SEM, HRTEM, and XRD analysis. It was shown that the controlled addition of a dicarboxylic acid leads not only to a change in the morphology of the nanostructures, but also to SnO2-SnO2/Sn3O4-Sn3O4-SnO phase transformations. A single-phase Sn3O4 in the form of the well-separated hexagonal nanoplates and mixed SnO2/Sn3O4 phases in the form of hierarchical flower-like structures were obtained in the presence of organic additives. The effects of concentration, redox activity of the acids and heat treatment on the basic characteristics of the synthesized tin oxide nanostructures and phase transformations in the synthesized materials are discussed.

  10. Influence of reaction time and synthesis temperature on the physical properties of ZnO nanoparticles synthesized by the hydrothermal method

    NASA Astrophysics Data System (ADS)

    Wasly, H. S.; El-Sadek, M. S. Abd; Henini, Mohamed

    2018-01-01

    Influence of synthesis temperature and reaction time on the structural and optical properties of ZnO nanoparticles synthesized by the hydrothermal method was investigated using X-ray diffraction (XRD), high resolution transmission electron microscopy (HR-TEM), energy-dispersive X-ray, Fourier transform infra-red spectroscopy, and UV-visible and fluorescence spectroscopy. The XRD pattern and HR-TEM images confirmed the presence of crystalline hexagonal wurtzite ZnO nanoparticles with average crystallite size in the range 30-40 nm. Their energy gap determined by fluorescence was found to depend on the synthesis temperature and reaction time with values in the range 2.90-3.78 eV. Thermal analysis, thermogravimetric and the differential scanning calorimetry were used to study the thermal reactions and weight loss with heat of the prepared ZnO nanoparticles.

  11. Growth Method-Dependent and Defect Density-Oriented Structural, Optical, Conductive, and Physical Properties of Solution-Grown ZnO Nanostructures.

    PubMed

    Rana, Abu Ul Hassan Sarwar; Lee, Ji Young; Shahid, Areej; Kim, Hyun-Seok

    2017-09-10

    It is time for industry to pay a serious heed to the application and quality-dependent research on the most important solution growth methods for ZnO, namely, aqueous chemical growth (ACG) and microwave-assisted growth (MAG) methods. This study proffers a critical analysis on how the defect density and formation behavior of ZnO nanostructures (ZNSs) are growth method-dependent. Both antithetical and facile methods are exploited to control the ZnO defect density and the growth mechanism. In this context, the growth of ZnO nanorods (ZNRs), nanoflowers, and nanotubes (ZNTs) are considered. The aforementioned growth methods directly stimulate the nanostructure crystal growth and, depending upon the defect density, ZNSs show different trends in structural, optical, etching, and conductive properties. The defect density of MAG ZNRs is the least because of an ample amount of thermal energy catered by high-power microwaves to the atoms to grow on appropriate crystallographic planes, which is not the case in faulty convective ACG ZNSs. Defect-centric etching of ZNRs into ZNTs is also probed and methodological constraints are proposed. ZNS optical properties are different in the visible region, which are quite peculiar, but outstanding for ZNRs. Hall effect measurements illustrate incongruent conductive trends in both samples.

  12. Immobilization and direct electrochemistry of glucose oxidase on a tetragonal pyramid-shaped porous ZnO nanostructure for a glucose biosensor.

    PubMed

    Dai, Zhihui; Shao, Guojian; Hong, Jianmin; Bao, Jianchun; Shen, Jian

    2009-01-01

    A tetragonal pyramid-shaped porous ZnO (TPSP-ZnO) nanostructure is used for the immobilization, direct electrochemistry and biosensing of proteins. The prepared ZnO has a large surface area and good biocompatibility. Using glucose oxidase (GOD) as a model, this shaped ZnO is tested for immobilization of proteins and the construction of electrochemical biosensors with good electrochemical performances. The interaction between GOD and TPSP-ZnO is examined by using AFM, N(2) adsorption isotherms and electrochemical methods. The immobilized GOD at a TPSP-ZnO-modified glassy carbon electrode shows a good direct electrochemical behavior, which depends on the properties of the TPSP-ZnO. Based on a decrease of the electrocatalytic response of the reduced form of GOD to dissolved oxygen, the proposed biosensor exhibits a linear response to glucose concentrations ranging from 0.05 to 8.2mM with a detection limit of 0.01mM at an applied potential of -0.50V which has better biosensing properties than those from other morphological ZnO nanoparticles. The biosensor shows good stability, reproducibility, low interferences and can diagnose diabetes very fast and sensitively. Such the TPSP-ZnO nanostructure provides a good matrix for protein immobilization and biosensor preparation.

  13. Multiscale modeling of nanostructured ZnO based devices for optoelectronic applications: Dynamically-coupled structural fields, charge, and thermal transport processes

    NASA Astrophysics Data System (ADS)

    Abdullah, Abdulmuin; Alqahtani, Saad; Nishat, Md Rezaul Karim; Ahmed, Shaikh; SIU Nanoelectronics Research Group Team

    Recently, hybrid ZnO nanostructures (such as ZnO deposited on ZnO-alloys, Si, GaN, polymer, conducting oxides, and organic compounds) have attracted much attention for their possible applications in optoelectronic devices (such as solar cells, light emitting and laser diodes), as well as in spintronics (such as spin-based memory, and logic). However, efficiency and performance of these hybrid ZnO devices strongly depend on an intricate interplay of complex, nonlinear, highly stochastic and dynamically-coupled structural fields, charge, and thermal transport processes at different length and time scales, which have not yet been fully assessed experimentally. In this work, we study the effects of these coupled processes on the electronic and optical emission properties in nanostructured ZnO devices. The multiscale computational framework employs the atomistic valence force-field molecular mechanics, models for linear and non-linear polarization, the 8-band sp3s* tight-binding models, and coupling to a TCAD toolkit to determine the terminal properties of the device. A series of numerical experiments are performed (by varying different nanoscale parameters such as size, geometry, crystal cut, composition, and electrostatics) that mainly aim to improve the efficiency of these devices. Supported by the U.S. National Science Foundation Grant No. 1102192.

  14. CuO-Decorated ZnO Hierarchical Nanostructures as Efficient and Established Sensing Materials for H2S Gas Sensors

    PubMed Central

    Vuong, Nguyen Minh; Chinh, Nguyen Duc; Huy, Bui The; Lee, Yong-Ill

    2016-01-01

    Highly sensitive hydrogen sulfide (H2S) gas sensors were developed from CuO-decorated ZnO semiconducting hierarchical nanostructures. The ZnO hierarchical nanostructure was fabricated by an electrospinning method following hydrothermal and heat treatment. CuO decoration of ZnO hierarchical structures was carried out by a wet method. The H2S gas-sensing properties were examined at different working temperatures using various quantities of CuO as the variable. CuO decoration of the ZnO hierarchical structure was observed to promote sensitivity for H2S gas higher than 30 times at low working temperature (200 °C) compared with that in the nondecorated hierarchical structure. The sensing mechanism of the hybrid sensor structure is also discussed. The morphology and characteristics of the samples were examined by scanning electron microscopy (SEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), UV-vis absorption, photoluminescence (PL), and electrical measurements. PMID:27231026

  15. Efficiency enhancement of ZnO nanostructure assisted Si solar cell based on fill factor enlargement and UV-blue spectral down-shifting

    NASA Astrophysics Data System (ADS)

    Gholizadeh, A.; Reyhani, A.; Parvin, P.; Mortazavi, S. Z.

    2017-05-01

    ZnO nanostructures (including nano-plates and nano-rods (NRs)) are grown in various temperatures and Ar/O2 flow rates using thermal chemical vapor deposition, which affect the structure, nano-plate/NR population, and the quality of ZnO nanostructures. X-ray diffraction (XRD) attests that the peak intensity of the crystallographic plane (1 0 0) is correlated to nano-plate abundance. Moreover, optical properties elucidate that the population of nano-plates in samples strongly affect the band gap, binding energy of the exciton, and UV-visible (UV-vis) absorption and spectral luminescence emissions. In fact, the exciton binding energy reduces from ~100 to 80 meV when the population of nano-plates increases in samples. Photovoltaic characteristics based on the drop-casting on Si solar cells reveals three dominant factors, namely, the equivalent series resistance, decreasing reflectance, and down-shifting, in order to scale up the absolute efficiency by 3%. As a consequence, the oxygen vacancies in ZnO nanostructures give rise to the down-shifting and increase of free-carriers, leading to a reduction in the equivalent series resistance and an enlargement of fill factor. To obtain a larger I sc, reduction of spectral reflectance is essential; however, the down-shifting process is shown to be dominant by lessening the surface electron-hole recombination rate over the UV-blue spectral range.

  16. Neoteric environmental detoxification of organic pollutants and pathogenic microbes via green synthesized ZnO nanoparticles.

    PubMed

    Jaffri, Shaan Bibi; Ahmad, Khuram Shahzad

    2018-06-13

    Present study has for the first time reported Prunus cerasifera leaf extract mediated zinc oxide nanoparticles in a green and one pot synthetic mode without utilization of any chemical reducing agents. Synthesized nanoparticles were analyzed by ultraviolet-visible (UV-Vis) spectroscopy, X-ray diffraction (XRD), fourier transmission infrared spectroscopy (FTIR) and scanning electron microscopy (SEM). UV-Vis peak was detected at 380 nm due to surface plasmon resonance (SPR). Variety of biomolecules were revealed by FTIR involved in reduction cum stabilization of zinc oxide nanoparticles. Wurtzite hexagonal geometry with an average crystallite size of 12 nm was obtained from XRD diffraction pattern. SEM exhibited size ranges of 80-100 nm and 60- 100 nm for 200 ℃ and 600 ℃ calcination temperatures. Synthesized nanoparticles were used as bio-cleaning photocatalysts against organic pollutants i.e. bromocresol green, bromophenol blue, methyl red and methyl blue, which yielded pseudo first order reaction kinetics (R 2 = 0.98, 0.92, 0.92, 0.90 respectively). Pollutants expressed higher degradation percentages in less than 14 min in direct solar irradiance. Moreover, synthesized nanoparticles were tested against resistant microbes i.e. Aspergillus niger, Aspergillus flavus, Aspergillus fumigatus, Aspergillus terreus, Penicillium chrysogenum, Fusarium solani, Lasiodiplodia theobromae, Xanthomonas axonopodis pv. citri and Psuedomonas syringae for development of new generation of antimicrobial agents.

  17. Electrodes synthesized from carbon nanostructures coated with a smooth and conformal metal adlayer

    DOEpatents

    Adzic, Radoslav; Harris, Alexander

    2014-04-15

    High-surface-area carbon nanostructures coated with a smooth and conformal submonolayer-to-multilayer thin metal films and their method of manufacture are described. The preferred manufacturing process involves the initial oxidation of the carbon nanostructures followed by a surface preparation process involving immersion in a solution with the desired pH to create negative surface dipoles. The nanostructures are subsequently immersed in an alkaline solution containing a suitable quantity of non-noble metal ions which adsorb at surface reaction sites. The metal ions are then reduced via chemical or electrical means. The nanostructures are exposed to a solution containing a salt of one or more noble metals which replace adsorbed non-noble surface metal atoms by galvanic displacement. The process can be controlled and repeated to obtain a desired film coverage. The resulting coated nanostructures may be used, for example, as high-performance electrodes in supercapacitors, batteries, or other electric storage devices.

  18. CuO urchin-nanostructures synthesized from a domestic hydrothermal microwave method

    SciTech Connect

    Keyson, D.; Laboratorio de Ensino de Ciencias, DME Universidade Federal da Paraiba, PB; Volanti, D.P.

    This letter reports the synthesis of CuO urchin-nanostructures by a simple and novel hydrothermal microwave method. The formation and growth of urchin-nanostructures is mainly affected by the addition of polyethylene glycol (PEG). The hierarchical malachite particles are uniform spheres with a diameter of 0.7-1.9 {mu}m. CuO urchin-nanostructures were characterized by X-ray diffraction (XRD), field-emission scanning electron microscopy (FEG-SEM) and nitrogen adsorption (BET). The specific surface area of the CuO nanostructured microspheres was about 170.5 m{sup 2}/g. A possible mechanism for the formation of such CuO urchin-nanostructures is proposed.

  19. Hydrothermal Synthesis and Acetylene Sensing Properties of Variety Low Dimensional Zinc Oxide Nanostructures

    PubMed Central

    Chen, Weigen; Peng, Shudi; Zeng, Wen

    2014-01-01

    Various morphologies of low dimensional ZnO nanostructures, including spheres, rods, sheets, and wires, were successfully synthesized using a simple and facile hydrothermal method assisted with different surfactants. Zinc acetate dihydrate was chosen as the precursors of ZnO nanostructures. We found that polyethylene glycol (PEG), polyvinylpyrrolidone (PVP), glycine, and ethylene glycol (EG) play critical roles in the morphologies and microstructures of the synthesized nanostructures, and a series of possible growth processes were discussed in detail. Gas sensors were fabricated using screen-printing technology, and their sensing properties towards acetylene gas (C2H2), one of the most important arc discharge characteristic gases dissolved in oil-filled power equipments, were systematically measured. The ZnO nanowires based sensor exhibits excellent C2H2 sensing behaviors than those of ZnO nanosheets, nanorods, and nanospheres, indicating a feasible way to develop high-performance C2H2 gas sensor for practical application. PMID:24672324

  20. Growth mechanism and optical properties of aligned hexagonal ZnO nanoprisms synthesized by noncatalytic thermal evaporation.

    PubMed

    Umar, Ahmad; Karunagaran, B; Kim, S H; Suh, E-K; Hahn, Y B

    2008-05-19

    Vertically aligned perfectly hexagonal-shaped ZnO nanoprisms have been grown on a Si(100) substrate via a noncatalytic thermal evaporation process by using metallic zinc powder in the presence of oxygen gas. The as-grown nanoprisms consist of ultra smooth Zn-terminated (0001) facets bounded with the {0110} surfaces. The as-synthesized products are single-crystalline with the wurtzite hexagonal phase and grown along the [0001] direction, as confirmed from the detailed structural investigations. The presence of a sharp and strong nonpolar optical phonon high-E2 mode at 437 cm(-1) in the Raman scattering spectrum further confirms good crystallinity and wurtzite hexagonal phase for the as-grown products. The as-grown nanoprisms exhibit a strong near-band-edge emission with a very weak deep-level emission in the room-temperature and low-temperature photoluminescence measurements, confirming good optical properties for the deposited products. Moreover, systematic time-dependent experiments were also performed to determine the growth process of the grown vertically aligned nanoprisms.

  1. In2O3-ZnO heterostructure development in electrical and photoluminescence properties of In2O3 1-D nanostructures

    NASA Astrophysics Data System (ADS)

    Shariati, M.; Ghafouri, V.

    2014-05-01

    Indium Oxide quasi one-dimensional (1D) nanostructures known as nanowires and nanorods synthesis using the thermal evaporation method, has been articulated. To nucleate growth sites, substrate seeding promoted 1D nanostructures growth. The catalyst-mediated growth mechanism showed more favorable morphologies and physical properties in under vacuum conditions associated with bottom-up technique. Scanning electron microscopy (SEM) results showed that the Zn-doped 1D nanostructures had spherical caps. The X-ray diffraction (XRD) pattern and energy-dispersive X-ray (EDX) spectrum indicated that these caps intensively associated with ZnO. Therefore, it was reasonable that the vapor-liquid-solid mechanism (VLS) was responsible for the growth of the In2O3-ZnO heterostructure nanowires. This technique enhances optical and electrical properties in nanostructures. The photoluminescence (PL) analysis in Zn-doped In2O3 nanowires and nanorods shows that the intensity of the visible and UV-region emissions overwhelmingly increases and resistance measurement professes the improvement of linear conductance in VLS growth mechanism.

  2. Flower-shaped ZnO nanocrystallite aggregates synthesized through a template-free aqueous solution method for dye-sensitized solar cells

    SciTech Connect

    Chang, Wei-Chen, E-mail: changpeter@iner.gov.tw; Institute of Nuclear Energy Research, Atomic Energy Council, Executive Yuan, 1000 Wenhua Rd., Chiaan Village, Lungtan, Taoyuan 325, Taiwan; Chen, Hung-Shuo

    Hierarchically structured flower-shaped aggregates composed of ZnO nanocrystals were synthesized through a template-free aqueous solution method. The synthesized nanocrystallite aggregates were demonstrated to be promising photoanode materials for dye-sensitized solar cells (DSSCs). Compared with commercially available ZnO nanoparticles (ZnONPs), the flower-like aggregates (ZnONFs), each having an overall dimension of 400–600 nm, exhibited similar dye loading but higher light-scattering ability, which led to a substantial increase in the light-harvesting efficiency of resulting cells. The unique morphology of ZnONFs also boosted the absorbed photon-to-electric current generation efficiency. Consequently, DSSCs constructed from ZnONFs showed significantly improved photocurrent and achieved an overall conversion efficiency ofmore » 4.42%, which was 47% higher than that attained by ZnONP-based cells.« less

  3. Comparison of structural and optical properties of TeO2 nanostructures synthesized using various substrate conditions

    NASA Astrophysics Data System (ADS)

    Jung, Taek-Kyun; Ryou, Min; Lee, Ji-Woon; Hyun, Soong-Keun; Na, Han Gil; Jin, Changhyun

    2017-11-01

    Several TeO2 low-dimensional nanostructures were prepared by thermal evaporation using four substrate conditions: (1) a bare substrate, (2) a scratched substrate, (3) a Au-catalyst-assisted substrate, and (4) a multi-walled carbon nanotube (MWCNT)-assisted substrate. Scanning electron microscopy and transmission electron microscopy analysis reveals that the morphologies of the nanostructures synthesized using these methods gradually changed from nanoparticles to ultra-thin nanowires with single tetragonal-type TeO2. Photoluminescence (PL) spectra reveal that the PL intensities of the TeO2 nanomaterials obtained using methods (1) and (2) are slightly increased, whereas the intensities of the TeO2 nanostructures obtained using methods (3) and (4) differ significantly depending on the initial substrate conditions. The emission peak is also blue-shifted from 440 nm to 430 nm for the scratched surface condition due to an excitonic transition. The increase in the blue emission for the MWCNT-assisted condition is attributed to the degree and type of excitons and defects in the TeO2 nanostructures.

  4. Ag nanodots decorated SiO2 coated ZnO core-shell nanostructure with enhanced luminescence property as potential imaging agent

    NASA Astrophysics Data System (ADS)

    Gupta, Jagriti; Barick, K. C.; Hassan, P. A.; Bahadur, Dhirendra

    2018-04-01

    Ag decorated silica coated ZnO nanocomposite (Ag@SiO2@ZnO NCs) has been synthesized by soft chemical approach. The physico-chemical properties of Ag@SiO2@ZnO NCs are investigated by various sophisticated characterization techniques such as X-ray diffraction, Transmission electron microscopy, X-ray photoelectron spectroscopy, UV-visible absorption and photoluminescent spectroscopy. X-ray diffraction confirms the phase formation of ZnO and Ag in nanocomposite. TEM micrograph clearly shows that Ag nanodots are well decorated over silica coated ZnO NCs. The photoluminescent study reveals the enhancement in the photoluminance property when the Ag nanodots are decorated over silica coated ZnO nanocomposite due to an electromagnetic coupling between excitons and plasmons. Furthermore, the photoluminescent property is an important tool for bio-imaging application, reveal that NCs give green and red emission after excitation with 488 and 535 nm. Therefore, low cytotoxicity and excellent fluorescence stability in vitro makes it a more suitable material for both cellular imaging and therapy for biomedical applications.

  5. The fabrication of diversiform nanostructure forests based on residue nanomasks synthesized by oxygen plasma removal of photoresist

    NASA Astrophysics Data System (ADS)

    Mao, Haiyang; Wu, Di; Wu, Wengang; Xu, Jun; Hao, Yilong

    2009-11-01

    A simple lithography-free approach for fabricating diversiform nanostructure forests is presented. The key technique of the approach is that randomly distributed nanoscale residues can be synthesized on substrates simply by removing photoresist with oxygen plasma bombardment. These nanoresidues can function as masks in the subsequent etching process for nanopillars. By further spacer and then deep etching processes, a variety of forests composed of regular, tulip-like or hollow-head nanopillars as well as nanoneedles are successfully achieved in different etching conditions. The pillars have diameters of 30-200 nm and heights of 400 nm-3 µm. The needles reach several microns in height, with their tips less than 10 nm in diameter. Moreover, microstructures containing these nanostructure forests, such as surface microchannels, have also been fabricated. This approach is compatible with conventional micro/nano-electromechanical system (MEMS/NEMS) fabrication.

  6. Microstructure and mechanical properties of thermoelectric nanostructured n-type silicon-germanium alloys synthesized employing spark plasma sintering

    NASA Astrophysics Data System (ADS)

    Bathula, Sivaiah; Gahtori, Bhasker; Jayasimhadri, M.; Tripathy, S. K.; Tyagi, Kriti; Srivastava, A. K.; Dhar, Ajay

    2014-08-01

    Owing to their high thermoelectric (TE) figure-of-merit, nanostructured Si80Ge20 alloys are evolving as a potential replacement for their bulk counterparts in designing efficient radio-isotope TE generators. However, as the mechanical properties of these alloys are equally important in order to avoid in-service catastrophic failure of their TE modules, we report the strength, hardness, fracture toughness, and thermal shock resistance of nanostructured n-type Si80Ge20 alloys synthesized employing spark plasma sintering of mechanically alloyed nanopowders of its constituent elements. These mechanical properties show a significant enhancement, which has been correlated with the microstructural features at nano-scale, delineated by transmission electron microscopy.

  7. Single-crystalline twinned ZnO nanoleaf structure via a facile hydrothermal process.

    PubMed

    Qiu, Jijun; Lil, Xiaomin; Gao, Xiangdong; Gan, Xiaoyan; He, Weizhen; Kim, Hyung-Kook; Hwang, Yoon-Hwae

    2011-03-01

    A single-crystalline twinned ZnO nanostructure with a 2-dimensional leaf-like morphology (nanoleaves) was synthesized using a facile hydrothermal strategy. The ZnO nanoleaves had 2-fold symmetric branches, which were identified by the existence of an inversion domain boundary (IDB) along the [2110] growth direction of the ribbon-like stems with both side surfaces of the stems terminated with a chemically active Zn-(0001) plane. A proposed growth mechanism suggested that the formation of IDB and the leaf-like shape are related to the dissolution of seed particles on the substrate surfaces and an OH- shielding effect in solution, respectively. Optical measurements revealed visible emission, suggesting the possession of defects in the as-grown and annealed ZnO nanoleaves. In addition, various ZnO nanostructures were synthesized by simply controlling the fabrication conditions.

  8. Interface-defect-mediated photocatalysis of mesocrystalline ZnO assembly synthesized in-situ via a template-free hydrothermal approach

    NASA Astrophysics Data System (ADS)

    Wang, Hui; Wang, Cuicui; Chen, Qifeng; Ren, Baosheng; Guan, Ruifang; Cao, Xiaofeng; Yang, Xiaopeng; Duan, Ran

    2017-08-01

    Both architecture construction and defects engineering of photocatalysts are highly vital in the photocatalytic activity. We report herein that the interface-defect-mediated photocatalytic activity of pompon-like ZnO (P-ZnO) mesocrystal photocatalyst synthesized via an aqueous approach, in the presence of sodium citrate without any other organic templates. The microstructure and defects of the diverse ZnO photocatalysts were examined with various techniques. The results indicated that the P-ZnO assemblies were composed of mesocrystal nanosheets exposed high energy (002) facet with high crystallinity. More importantly, the defects located at the interfaces among the nanocrystals in ZnO mesocrystals played an important role in the photocatalytic activity than that of interstitial zinc vacancies in bulk, which was confirmed by photocatalytic degradation of organic pollutants, such as methylene blue (MB) and 2,4,6-trichlorophenol (2,4,6-TCP). The results showed that the P-ZnO exhibited higher photocatalytic activity than that of the nanosized ZnO (N-ZnO), which could be attributed to not only the unique mesocrystal structure and high energy (002) facet exposed, but also the defects located at interfaces among nanocrystals in ZnO mesocrystals. In addition, the formation mechanism of the P-ZnO was investigated via a time-dependent method. It was found that the formation of P-ZnO hierarchical architecture assembled with ZnO mesocrystals involved a nonclassical crystallization growth and Ostwald Ripening process. This study provides a perspective on the improvement in photocatalytic activity via adjusting the bulk and interface defects and construction of hierarchical architectures of semiconductors.

  9. ZnO nanostructures as electron extraction layers for hybrid perovskite thin films

    NASA Astrophysics Data System (ADS)

    Nikolaidou, Katerina; Sarang, Som; Tung, Vincent; Lu, Jennifer; Ghosh, Sayantani

    Optimum interaction between light harvesting media and electron transport layers is critical for the efficient operation of photovoltaic devices. In this work, ZnO layers of different morphologies are implemented as electron extraction and transport layers for hybrid perovskite CH3NH3PbI3 thin films. These include nanowires, nanoparticles, and single crystalline film. Charge transfer at the ZnO/perovskite interface is investigated and compared through ultra-fast characterization techniques, including temperature and power dependent spectroscopy, and time-resolved photoluminescence. The nanowires cause an enhancement in perovskite emission, which may be attributed to increased scattering and grain boundary formation. However, the ZnO layers with decreasing surface roughness exhibit better electron extraction, as inferred from photoluminescence quenching, reduction in the number of bound excitons, and reduced exciton lifetime in CH3NH3PbI3 samples. This systematic study is expected to provide an understanding of the fundamental processes occurring at the ZnO-CH3NH3PbI3 interface and ultimately, provide guidelines for the ideal configuration of ZnO-based hybrid Perovskite devices. This research was supported by National Aeronautics and Space administration (NASA) Grant No: NNX15AQ01A.

  10. Self-Styled ZnO Nanostructures Promotes the Cancer Cell Damage and Supresses the Epithelial Phenotype of Glioblastoma

    NASA Astrophysics Data System (ADS)

    Wahab, Rizwan; Kaushik, Neha; Khan, Farheen; Kaushik, Nagendra Kumar; Choi, Eun Ha; Musarrat, Javed; Al-Khedhairy, Abdulaziz A.

    2016-01-01

    Extensive researches have been done on the applications of zinc oxide nanoparticles (ZnO-NPs) for the biological purposes. However, the role and toxicity mechanisms of ZnO nanostructures (ZnO-NSts) such as nanoplates (NPls), nanorods (NRs), nanosheets (NSs), nanoflowers (NFs) on cancer cells are not largely known. Present study was focused to investigate the possible mechanisms of apoptosis induced by self-designed ZnO-NSts, prepared at fix pH via solution process and exposed against human T98G gliomas including various cancers and non-malignant embryonic kidney HEK293, MRC5 fibroblast cells. NSts were used for the induction of cell death in malignant human T98G gliomas including various cancers and compared with the non-malignant cells. Notably, NRs were found to induce higher cytotoxicity, inhibitory effects on cancer and normal cells in a dose dependent manner. We also showed that NRs induced cancer cell death through oxidative stress and caspase-dependent pathways. Furthermore, quantitative and qualitative analysis of ZnO-NSts have also been confirmed by statistical analytical parameters such as precision, accuracy, linearity, limits of detection and limit of quantitation. These self-styled NSts could provide new perception in the research of targeted cancer nanotechnology and have potentiality to improve new therapeutic outcomes with poor diagnosis.

  11. Platinum-based electrocatalysts synthesized by depositing contiguous adlayers on carbon nanostructures

    DOEpatents

    Adzic, Radoslav R.; Harris, Alexander

    2015-10-06

    High-surface-area carbon nanostructures coated with a smooth and conformal submonolayer-to-multilayer thin metal films and their method of manufacture are described. The manufacturing process may involve initial oxidation of the carbon nanostructures followed by immersion in a solution with the desired pH to create negative surface dipoles. The nanostructures are subsequently immersed in an alkaline solution containing non-noble metal ions which adsorb at surface reaction sites. The metal ions are then reduced via chemical or electrical means and the nanostructures are exposed to a solution containing a salt of one or more noble metals which replace adsorbed non-noble surface metal atoms by galvanic displacement. Subsequent film growth may be performed via the initial quasi-underpotential deposition of a non-noble metal followed by immersion in a solution comprising a more noble metal. The resulting coated nanostructures may be used, for example, as high-performance electrodes in supercapacitors, batteries, or other electric storage devices.

  12. Platinum-based electrocatalysts synthesized by depositing contiguous adlayers on carbon nanostructures

    DOEpatents

    Adzic, Radoslav; Harris, Alexander

    2013-03-26

    High-surface-area carbon nanostructures coated with a smooth and conformal submonolayer-to-multilayer thin metal films and their method of manufacture are described. The preferred manufacturing process involves the initial oxidation of the carbon nanostructures followed by immersion in a solution with the desired pH to create negative surface dipoles. The nanostructures are subsequently immersed in an alkaline solution containing non-noble metal ions which adsorb at surface reaction sites. The metal ions are then reduced via chemical or electrical means and the nanostructures are exposed to a solution containing a salt of one or more noble metals which replace adsorbed non-noble surface metal atoms by galvanic displacement. Subsequent film growth may be performed via the initial quasi-underpotential deposition of a non-noble metal followed by immersion in a solution comprising a more noble metal. The resulting coated nanostructures may be used, for example, as high-performance electrodes in supercapacitors, batteries, or other electric storage devices.

  13. Ultra-Fast Microwave Synthesis of ZnO Nanorods on Cellulose Substrates for UV Sensor Applications

    PubMed Central

    Pimentel, Ana; Samouco, Ana; Araújo, Andreia; Martins, Rodrigo; Fortunato, Elvira

    2017-01-01

    In the present work, tracing and Whatman papers were used as substrates to grow zinc oxide (ZnO) nanostructures. Cellulose-based substrates are cost-efficient, highly sensitive and environmentally friendly. ZnO nanostructures with hexagonal structure were synthesized by hydrothermal under microwave irradiation using an ultrafast approach, that is, a fixed synthesis time of 10 min. The effect of synthesis temperature on ZnO nanostructures was investigated from 70 to 130 °C. An Ultra Violet (UV)/Ozone treatment directly to the ZnO seed layer prior to microwave assisted synthesis revealed expressive differences regarding formation of the ZnO nanostructures. Structural characterization of the microwave synthesized materials was carried out by scanning electron microscopy (SEM) and X-ray diffraction (XRD). The optical characterization has also been performed. The time resolved photocurrent of the devices in response to the UV turn on/off was investigated and it has been observed that the ZnO nanorod arrays grown on Whatman paper substrate present a responsivity 3 times superior than the ones grown on tracing paper. By using ZnO nanorods, the surface area-to-volume ratio will increase and will improve the sensor sensibility, making these types of materials good candidates for low cost and disposable UV sensors. The sensors were exposed to bending tests, proving their high stability, flexibility and adaptability to different surfaces. PMID:29140304

  14. Morphology and phase transformations of tin oxide nanostructures synthesized by the hydrothermal method in the presence of dicarboxylic acids

    SciTech Connect

    Zima, Tatyana, E-mail: zima@solid.nsc.ru; Novosibirsk State Technical University, 20 K. Marx Prospect, Novosibirsk 630092; Bataev, Ivan

    A new approach to the synthesis of non-stoichiometric tin oxide structures with different morphologies and the phase compositions has been evaluated. The nanostructures were synthesized by hydrothermal treatment of the mixtures of dicarboxylic acids ― aminoterephthalic or oxalic ― with nanocrystalline SnO{sub 2} powder, which was obtained via the sol-gel technology. The products were characterized by Raman and IR spectroscopy, SEM, HRTEM, and XRD analysis. It was shown that the controlled addition of a dicarboxylic acid leads not only to a change in the morphology of the nanostructures, but also to SnO{sub 2}–SnO{sub 2}/Sn{sub 3}O{sub 4}–Sn{sub 3}O{sub 4}–SnO phase transformations.more » A single-phase Sn{sub 3}O{sub 4} in the form of the well-separated hexagonal nanoplates and mixed SnO{sub 2}/Sn{sub 3}O{sub 4} phases in the form of hierarchical flower-like structures were obtained in the presence of organic additives. The effects of concentration, redox activity of the acids and heat treatment on the basic characteristics of the synthesized tin oxide nanostructures and phase transformations in the synthesized materials are discussed. - Graphical abstract: The controlled addition of aminoterephthalic or oxalic acid leads not only to a change in the morphology of the nanostructures, but also to SnO{sub 2}–SnO{sub 2}/Sn{sub 3}O{sub 4}–Sn{sub 3}O{sub 4}–SnO phase transformations. - Highlights: • A new approach to the synthesis of non-stoichiometric tin oxide structures is studied. • Tin oxide structures are synthesized via hydrothermal method with dicarboxylic acids. • Morphology and phase composition are changed with redox activity and dosage of acid. • The redox activity of acid has an effect on ratio of SnO and SnO{sub 2} in crystal structure. • A pure phase Sn{sub 3}O{sub 4} nanoplates and SnO{sub 2}/Sn{sub 3}O{sub 4} hierarchical structures are formed.« less

  15. The optical properties of α-Fe2O3 nanostructures synthesized with different immersion time

    NASA Astrophysics Data System (ADS)

    Ahmad, W. R. W.; Mamat, M. H.; Zoolfakar, A. S.; Khusaimi, Z.; Yusof, M. M.; Ismail, A. S.; Saidi, S. A.; Rusop, M.

    2018-05-01

    In this study, nanostructured hematite (α-Fe2O3) thin films have been prepared successfully by sonicated immersion method on fluorine-doped tin oxide (FTO) coated glass substrate. The effect of the immersion time on the structural and optical properties of α-Fe2O3 nanostructure were investigated for a variation of immersion time ranging from 1 to 4 hour. From the characterization results, the surface morphology of the sample prepared in 4 hours immersion process has exhibited highest porosity, and the highest absorbance properties were found in the same sample. These results suggest that the different time duration during immersion process play important roles in optical properties of α-Fe2O3 nanostructures.

  16. Influence of ZnO seed layer precursor molar ratio on the density of interface defects in low temperature aqueous chemically synthesized ZnO nanorods/GaN light-emitting diodes

    SciTech Connect

    Alnoor, Hatim, E-mail: hatim.alnoor@liu.se; Iandolo, Donata; Willander, Magnus

    Low temperature aqueous chemical synthesis (LT-ACS) of zinc oxide (ZnO) nanorods (NRs) has been attracting considerable research interest due to its great potential in the development of light-emitting diodes (LEDs). The influence of the molar ratio of the zinc acetate (ZnAc): KOH as a ZnO seed layer precursor on the density of interface defects and hence the presence of non-radiative recombination centers in LT-ACS of ZnO NRs/GaN LEDs has been systematically investigated. The material quality of the as-prepared seed layer as quantitatively deduced by the X-ray photoelectron spectroscopy is found to be influenced by the molar ratio. It is revealedmore » by spatially resolved cathodoluminescence that the seed layer molar ratio plays a significant role in the formation and the density of defects at the n-ZnO NRs/p-GaN heterostructure interface. Consequently, LED devices processed using ZnO NRs synthesized with molar ratio of 1:5 M exhibit stronger yellow emission (∼575 nm) compared to those based on 1:1 and 1:3 M ratios as measured by the electroluminescence. Furthermore, seed layer molar ratio shows a quantitative dependence of the non-radiative defect densities as deduced from light-output current characteristics analysis. These results have implications on the development of high-efficiency ZnO-based LEDs and may also be helpful in understanding the effects of the ZnO seed layer on defect-related non-radiative recombination.« less

  17. Influence of ZnO seed layer precursor molar ratio on the density of interface defects in low temperature aqueous chemically synthesized ZnO nanorods/GaN light-emitting diodes

    NASA Astrophysics Data System (ADS)

    Alnoor, Hatim; Pozina, Galia; Khranovskyy, Volodymyr; Liu, Xianjie; Iandolo, Donata; Willander, Magnus; Nur, Omer

    2016-04-01

    Low temperature aqueous chemical synthesis (LT-ACS) of zinc oxide (ZnO) nanorods (NRs) has been attracting considerable research interest due to its great potential in the development of light-emitting diodes (LEDs). The influence of the molar ratio of the zinc acetate (ZnAc): KOH as a ZnO seed layer precursor on the density of interface defects and hence the presence of non-radiative recombination centers in LT-ACS of ZnO NRs/GaN LEDs has been systematically investigated. The material quality of the as-prepared seed layer as quantitatively deduced by the X-ray photoelectron spectroscopy is found to be influenced by the molar ratio. It is revealed by spatially resolved cathodoluminescence that the seed layer molar ratio plays a significant role in the formation and the density of defects at the n-ZnO NRs/p-GaN heterostructure interface. Consequently, LED devices processed using ZnO NRs synthesized with molar ratio of 1:5 M exhibit stronger yellow emission (˜575 nm) compared to those based on 1:1 and 1:3 M ratios as measured by the electroluminescence. Furthermore, seed layer molar ratio shows a quantitative dependence of the non-radiative defect densities as deduced from light-output current characteristics analysis. These results have implications on the development of high-efficiency ZnO-based LEDs and may also be helpful in understanding the effects of the ZnO seed layer on defect-related non-radiative recombination.

  18. Screen-Printing of ZnO Nanostructures from Sol-Gel Solutions for Their Application in Dye-Sensitized Solar Cells.

    PubMed

    Sarkar, Kuhu; Braden, Erik V; Bonke, Shannon A; Bach, Udo; Müller-Buschbaum, Peter

    2015-08-24

    Diblock copolymers have been used in sol-gel synthesis to successfully tailor the nanoscale morphology of thin ZnO films. As the fabrication of several-micron-thick mesoporous films such as those required in dye-sensitized solar cells (DSSCs) was difficult with this approach, we exploited the benefits of diblock-copolymer-directed synthesis that made it compatible with screen printing. The simple conversion of the diblock copolymer ZnO precursor sol to a screen-printing paste was not possible as it resulted in poor film properties. To overcome this problem, an alternative route is proposed in which the diblock copolymer ZnO precursor sol is first blade coated and calcined, then converted to a screen-printing paste. This allows the benefits of diblock-copolymer-directed particle formation to be compatible with printing methods. The morphologies of the ZnO nanostructures were studied by SEM and correlated with the current density-voltage characteristics. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  19. Microwave-assisted synthesis of C-doped TiO2 and ZnO hybrid nanostructured materials as quantum-dots sensitized solar cells

    NASA Astrophysics Data System (ADS)

    Rangel-Mendez, Jose R.; Matos, Juan; Cházaro-Ruiz, Luis F.; González-Castillo, Ana C.; Barrios-Yáñez, Guillermo

    2018-03-01

    The microwave-assisted solvothermal synthesis of C-doped TiO2 and ZnO hybrid materials was performed. Saccharose, titanium isopropoxide and zinc acetate were used as organic and inorganic sources for the synthesis. The influence of temperature and reaction time on the textural and optoelectronic properties of the hybrid materials was verified. Carbon quantum-dots of TiO2 and ZnO nanostructured spheres were obtained in a second pot by controlled calcination steps of the precursor hybrid materials. A carefully characterization by adsorption-desorption N2 isotherms, XRD, XPS, SEM, UV-vis/DR and electro- and photo-electrochemistry properties of the carbon quantum-dots TiO2 and ZnO spheres was performed. The photoelectrochemical activity of TiO2-C and ZnO-C films proved to be dependent on the conditions of synthesis. It was found a red-shift in the energy band gap of the semiconductors with values of 3.02 eV and 3.13 eV for the TiO2-C and ZnO-C, respectively, clearly lower than those on bare semiconductors, which is associated with the C-doping effect. From the photo-electrochemistry characterization of C-doped TiO2 and ZnO films can be concluded that the present materials have potential applications as photoelectrodes for quantum-dots sensitized solar cells.

  20. In-situ functionalization of mesoporous hexagonal ZnO synthesized in task specific ionic liquid as a photocatalyst for elimination of SO2, NOx, and CO

    NASA Astrophysics Data System (ADS)

    Kowsari, Elaheh; Abdpour, Soheil

    2017-12-01

    A novel mesoporous structure of zinc oxide was synthesized in hydrothermal autocalve in the presence of a functional ionic liquid (FIL) {[CH2CH2] O2 (mm)2}. This FIL with ether groups was used simultaneously as a designer templating agent and a source of the hydroxyl radical. The presence of this ionic liquid led to producing ethylene glycol in the reaction media, which adsorb on the surface of mesoporous hexagonal ZnO plates. These mesoporous structures can adsorb pollutant gases and increase photocatalytic oxidation of pollutant gases in compare with commercial ZnO nanoparticles and agglomerated nanoparticles synthesized in this work. XPS data confirmed ethylene glycol production by the ionic liquid, which could prove a role for ionic liquids as designers. The estimated BET surface area values of ZnO hexagonal mesoporous plates and agglomerated particles were 84 m2/g and 12 m2/g respectively. Optical properties of the mesoporous structures were analyzed by photoluminescence spectroscopy and diffuse reflectance UV-visible spectroscopy. The performance of these structures as efficient photocatalysts was further demonstrated by their removal of NOx, SO2, and CO under UV irradiation. The removal of NOx, SO2, and CO under UV irradiation was 56%, 81%, and 35% respectively, after 40 min of irradiation time. Reusability of the photocatalyst was determined; the results show no significant decrease of activity of photocatalyst. after five cycles.

  1. Fabrication and characterization of hexagonally patterned quasi-1D ZnO nanowire arrays

    PubMed Central

    2014-01-01

    Quasi-one-dimensional (quasi-1D) ZnO nanowire arrays with hexagonal pattern have been successfully synthesized via the vapor transport process without any metal catalyst. By utilizing polystyrene microsphere self-assembled monolayer, sol–gel-derived ZnO thin films were used as the periodic nucleation sites for the growth of ZnO nanowires. High-quality quasi-1D ZnO nanowires were grown from nucleation sites, and the original hexagonal periodicity is well-preserved. According to the experimental results, the vapor transport solid condensation mechanism was proposed, in which the sol–gel-derived ZnO film acting as a seed layer for nucleation. This simple method provides a favorable way to form quasi-1D ZnO nanostructures applicable to diverse fields such as two-dimensional photonic crystal, nanolaser, sensor arrays, and other optoelectronic devices. PMID:24521308

  2. Shape-Selective Syntheses of Gold and Copper Nanostructures: Insights From Density-Functional Theory and Molecular Dynamics

    NASA Astrophysics Data System (ADS)

    Liu, Shih-Hsien

    Density-functional theory (DFT) and molecular dynamics (MD) were used to resolve the origins of shape-selective syntheses of {111}-faceted Au nanostructures mediated by polyvinylpyrrolidone (PVP) as well as {100}-faceted Cu nanostructures mediated by hex- adecylamine(HDA) seen in experiment. For the work in PVP on Au surfaces, the hexagonal reconstruction of Au(100) was considered. DFT results indicate that the Au(111) surface covered by the PVP segment, 2-pyrrolidone (2P), has a lower surface energy than the 2P- covered (5 x 1) Au(100)-hex surface, and that PVP may exhibit a binding affinity for Au(111) comparable to or greater than (5 x 1) Au(100)-hex. With MD, it is shown that the PVP-covered Au(111) surface has a lower surface energy than the PVP-covered (5 x 1) Au(100)-hex surface, and that the atactic PVP isosamer chains have a binding affinity for Au(111) comparable to (5 x 1) Au(100)-hex. Also, the (5 x 1) Au(100)-hex surface may have a higher flux of Au atoms than the Au(111) surface. Therefore, the Au(111) surface would be thermodynamically and kinetically favored in PVP-mediated syntheses, leading to {111}-faceted Au nanostructures. For the work in HDA on Cu surfaces, DFT results show that the HDA-covered Cu(100) surface has a slightly higher surface energy than the HDA- covered Cu(111) surface. However, HDA has a significant binding preference on Cu(100) over Cu(111). Therefore, the Cu(100) surface would be kinetically favored in HDA-mediated syn- theses, leading to {100}-faceted Cu nanostructures. Further, a metal-organic many-body (MOMB) force field for HDA-Cu interactions was developed based on the DFT work, and the force field was used to resolve the HDA binding patterns on Cu(100) at molecular level. With MD, it is found that decylamine (DA) may be used as an effective capping agent in the synthesis of {100}-faceted Cu nanostructures since DA as well as HDA are organized on Cu surfaces and have the same binding preference on Cu(100) over Cu(111

  3. Structural, chemical and optical evaluation of Cu-doped ZnO nanoparticles synthesized by an aqueous solution method

    SciTech Connect

    Iribarren, A., E-mail: augusto@imre.oc.uh.cu; Hernández-Rodríguez, E.; Maqueira, L.

    Highlights: • Cu-doped ZnO nanoparticles obtained by chemical synthesis. • Substitutional or interstitial Cu into ZnO lead specific structural, chemical, and optical changes. • Incorporation efficiency of Cu atoms in ZnO as a function of the Cu concentration in the precursor dissolution. - Abstract: In this work a study of ZnO and Cu-doped ZnO nanoparticles obtained by chemical synthesis in aqueous media was carried out. Structural analysis gave the dominant presence of wurtzite ZnO phase forming a solid solution Zn{sub 1−x}Cu{sub x}O. For high Cu doping CuO phase is also present. For low Cu concentration the lattice shrinks due tomore » Cu atoms substitute Zn atoms. For high Cu concentration the lattice enlarges due to predominance of interstitial Cu. From elemental analysis we determined and analyzed the incorporation efficiency of Cu atoms in Zn{sub 1−x}Cu{sub x}O as a function of the Cu concentration in the precursor dissolution. Combining structural and chemical results we described the Cu/Zn precursor concentrations r{sub w} in which the solid solution of Cu in ZnO is predominant. In the region located at r{sub w} ≈ 0.2–0.3 it is no longer valid. For Cu/Zn precursor concentration r{sub w} > 0.3 interstitial Cu dominates, and some amount of copper oxide appears. As the Cu concentration increases, the effective size of nanoparticles decreases. Photoluminescence (PL) measurements of the Cu-doped ZnO nanoparticles were carried out and analyzed.« less

  4. Effect of indium on photovoltaic property of n-ZnO/p-Si heterojunction device prepared using solution-synthesized ZnO nanowire film

    NASA Astrophysics Data System (ADS)

    Kathalingam, Adaikalam; Kim, Hyun-Seok; Park, Hyung-Moo; Valanarasu, Santiyagu; Mahalingam, Thaiyan

    2015-01-01

    Preparation of n-ZnO/p-Si heterostructures using solution-synthesized ZnO nanowire films and their photovoltaic characterization is reported. The solution-grown ZnO nanowire film is characterized using scanning electron microscope, electron dispersive x-ray, and optical absorption studies. Electrical and photovoltaic properties of the fabricated heterostructures are studied using e-beam-evaporated aluminum as metal contacts. In order to use transparent contact and to simultaneously collect the photogenerated carriers, sandwich-type solar cells were fabricated using ZnO nanorod films grown on p-silicon and indium tin oxide (ITO) coated glass as ITO/n-ZnO NR/p-Si. The electrical properties of these structures are analyzed from current-voltage (I-V) characteristics. ZnO nanowire film thickness-dependent photovoltaic properties are also studied. Indium metal was also deposited over the ZnO nanowires and its effects on the photovoltaic response of the devices were studied. The results demonstrated that all the samples exhibit a strong rectifying behavior indicating the diode nature of the devices. The sandwich-type ITO/n-ZnO NR/p-Si solar cells exhibit improved photovoltaic performance over the Al-metal-coated n-ZnO/p-Si structures. The indium deposition is found to show enhancement in photovoltaic behavior with a maximum open-circuit voltage (Voc) of 0.3 V and short-circuit current (Isc) of 70×10-6 A under ultraviolet light excitation.

  5. Second-harmonic generation of ZnO nanoparticles synthesized by laser ablation of solids in liquids

    NASA Astrophysics Data System (ADS)

    Rocha-Mendoza, Israel; Camacho-López, Santiago; Luna-Palacios, Yryx Y.; Esqueda-Barrón, Yasmín; Camacho-López, Miguel A.; Camacho-López, Marco; Aguilar, Guillermo

    2018-02-01

    We report the synthesis of small zinc oxide nanoparticles (ZnO NPs) based colloidal suspensions and the study of second-harmonic generation from aggregated ZnO NPs deposited on glass substrates. The colloidal suspensions were obtained using the laser ablation of solids in liquids technique, ablating a Zn solid target immersed in acetone as the liquid medium, with ns-laser pulses (1064 nm) of a Nd-YAG laser. The per pulse laser fluence, the laser repetition rate frequency and the ablation time were kept constant. The absorption evolution of the obtained suspensions was optically characterized through absorption spectroscopy until stabilization. Raman spectroscopy, SEM and HRTEM were used to provide evidence of the ZnO NPs structure. HRTEM results showed that 5-8 nm spheroids ZnO NPs were obtained. Strong second-harmonic signal is obtained from random ZnO monocrystalline NPs and from aggregated ZnO NPs, suggesting that the high efficiency of the nonlinear process may not depend on the NPs size or aggregation state.

  6. Tailoring surface and photocatalytic properties of ZnO and nitrogen-doped ZnO nanostructures using microwave-assisted facile hydrothermal synthesis

    NASA Astrophysics Data System (ADS)

    Rangel, R.; Cedeño, V.; Ramos-Corona, A.; Gutiérrez, R.; Alvarado-Gil, J. J.; Ares, O.; Bartolo-Pérez, P.; Quintana, P.

    2017-08-01

    Microwave hydrothermal synthesis, using an experimental 23 factorial design, was used to produce tunable ZnO nano- and microstructures, and their potential as photocatalysts was explored. Photocatalytic reactions were conducted in a microreactor batch system under UV and visible light irradiation, while monitoring methylene blue degradation, as a model system. The variables considered in the microwave reactor to produce ZnO nano- or microstructures, were time, NaOH concentration and synthesis temperature. It was found that, specific surface area and volume/surface area ratio were affected as a consequence of the synthesis conditions. In the second stage, the samples were plasma treated in a nitrogen atmosphere, with the purpose of introducing nitrogen into the ZnO crystalline structure. The central idea is to induce changes in the material structure as well as in its optical absorption, to make the plasma-treated material useful as photocatalyst in the visible region of the electromagnetic spectrum. Pristine ZnO and nitrogen-doped ZnO compounds were characterized by means of X-ray diffraction (XRD), scanning electron microscopy (SEM), specific surface area (BET), XPS, and UV-Vis diffuse reflectance spectroscopy. The results show that the methodology presented in this work is effective in tailoring the specific surface area of the ZnO compounds and incorporation of nitrogen into their structure, factors which in turn, affect its photocatalytic behavior.

  7. CHARACTERIZATION OF FLAME-SYNTHESIZED FE, CO, OR MN-DOPED TITANIA NANOSTRUCTURED PARTICLES

    EPA Science Inventory

    The flame-synthesized catalysts have higher surface areas than commercial-grade titania and are composed of nanometer-sized primary particles with low internal porosity. Preliminary studies suggest that flame-synthesized iron-doped titania may be photoactivated in the visible lig...

  8. Particle size and shape modification of hydroxyapatite nanostructures synthesized via a complexing agent-assisted route.

    PubMed

    Mohandes, Fatemeh; Salavati-Niasari, Masoud

    2014-07-01

    In this work, hydroxyapatite (HAP), Ca10(PO4)6(OH)2, nanostructures including nanorods, nanobundles and nanoparticles have been prepared via a simple precipitation method. In the present method, Ca(NO3)2·4H2O and (NH4)2HPO4 were used as calcium and phosphorus precursors, respectively. Besides, the Schiff bases derived from 2-hydroxyacetophenone and different diamines were used as complexing agents for the in situ formation of Ca(2+) complexes. The formation mechanism of 0-D and 1-D nanostructures of HAP was also considered. When the complexing agents could coordinate to the Ca(2+) ions through N and O atoms to form the [CaN2O2](2+) complexes, HAP nanoparticles were generated. On the other hand, nanorods and nanobundles of HAP were obtained by forming the [CaN2](2+) as well as [CaO2](2+) complexes in the reaction solution. This work is the first successful synthesis of pure HAP nanostructures in the presence of Schiff bases instead of using the common surfactants. Copyright © 2014 Elsevier B.V. All rights reserved.

  9. Percentage of different aluminum doping influence the morphological and optical properties of ZnO nanostructured growth for sensor application

    SciTech Connect

    Mohamed, R., E-mail: ruziana12@gmail.com; NANO-SciTech Centre, Institue of Science, Universiti Teknologi MARA, 40450 Shah Alam, Selangor; Faculty of Applied Sciences, Universiti Teknologi MARA Pahang, 26400 Bandar Tun Razak Jengka, Pahang

    In this work, Zinc Oxide (ZnO) with different aluminum (Al) doping percentage was synthesis by sol gel immersion method. Al doped ZnO at various doping percentage from 1, 2, 3, 4 and 5. It was found that with different Al percentage influence the morphological and optical properties of ZnO growth. Field Emission Scanning Electron Microscope (FESEM) image showed the use of different Al doping causes the difference in geometry and size of ZnO nanorods growth. Based on UV-Vis spectroscopy, the transmittance at 1% Al doping has the highest spectrum.

  10. Influence of solvents on the changes in structure, purity, and in vitro characteristics of green-synthesized ZnO nanoparticles from Costus igneus

    NASA Astrophysics Data System (ADS)

    Nandhini, G.; Suriyaprabha, R.; Maria Sheela Pauline, W.; Rajendran, V.; Aicher, Wilhelm Karl; Awitor, Oscar Komla

    2018-05-01

    The present study is intended to produce high-purity zinc oxide nanoparticles from the leaves of Costus igneus and zinc acetate precursor via sustainable methods by the tribulation with three different solvents (hot water, methanol, and acetone) for the extraction of plant compounds. While examining the physico-chemical characteristics of ZnO nanoparticles incurred by the catalysis of plant bioactive compounds extracted from different solvents, the hot water extract-based green synthesis process yields higher purity (99.89%) and smaller particle size (94 nm) than other solvents. The optimization of the solvents used for the green synthesis of nanoparticles renders key identification in appropriate extraction of bioactive compounds suitable for the nucleation/production of nanoparticles in addition to annealing temperature. The impregnable usage of ZnO nanoparticles in clinical applications is further confirmed based on the treatment of particles (1-10 mg ml-1) against Gram-positive (S. aureus and S. epidermis) and Gram-negative bacteria (E. coli and K. pneumoniae) with respect to their growth inhibition. An in-force growth inhibition against particular S. aureus and S. epidermis imparted by the low concentration of ZnO nanoparticles signifies the utilization and consumption of green-synthesized high-purity nanoparticles for therapeutic and cosmetic applications.

  11. Piezoelectric and opto-electrical properties of silver-doped ZnO nanorods synthesized by low temperature aqueous chemical method

    SciTech Connect

    Nour, E. S., E-mail: eiman.satti.osman@liu.se; Echresh, A.; Willander, M.

    2015-07-15

    In this paper, we have synthesized Zn{sub 1−x}Ag{sub x}O (x = 0, 0.03, 0.06, and 0.09) nanorods (NRs) via the hydrothermal method at low temperature on silicon substrate. The characterization and comparison between the different Zn{sub 1−x}Ag{sub x}O samples, indicated that an increasing Ag concentration from x = 0 to a maximum of x = 0.09; All samples show a preferred orientation of (002) direction with no observable change of morphology. As the quantity of the Ag dopant was changed, the transmittances, as well as the optical band gap were decreased. X-ray photoelectron spectroscopy data clearly indicate the presence ofmore » Ag in ZnO crystal lattice. A nanoindentation-based technique was used to measure the effective piezo-response of different concentrations of Ag for both direct and converse effects. The value of the piezoelectric coefficient (d{sub 33}) as well as the piezo potential generated from the ZnO NRs and Zn{sub 1−x}Ag{sub x}O NRs was found to decrease with the increase of Ag fraction. The finding in this investigation reveals that Ag doped ZnO is not suitable for piezoelectric energy harvesting devices.« less

  12. Non-covalently functionalized carbon nanostructures for synthesizing carbon-based hybrid nanomaterials.

    PubMed

    Li, Haiqing; Song, Sing I; Song, Ga Young; Kim, Il

    2014-02-01

    Carbon nanostructures (CNSs) such as carbon nanotubes, graphene sheets, and nanodiamonds provide an important type of substrate for constructing a variety of hybrid nanomaterials. However, their intrinsic chemistry-inert surfaces make it indispensable to pre-functionalize them prior to immobilizing additional components onto their surfaces. Currently developed strategies for functionalizing CNSs include covalent and non-covalent approaches. Conventional covalent treatments often damage the structure integrity of carbon surfaces and adversely affect their physical properties. In contrast, the non-covalent approach offers a non-destructive way to modify CNSs with desired functional surfaces, while reserving their intrinsic properties. Thus far, a number of surface modifiers including aromatic compounds, small-molecular surfactants, amphiphilic polymers, and biomacromolecules have been developed to non-covalently functionalize CNS surfaces. Mediated by these surface modifiers, various functional components such as organic species and inorganic nanoparticles were further decorated onto their surfaces, resulting in versatile carbon-based hybrid nanomaterials with broad applications in chemical engineering and biomedical areas. In this review, the recent advances in the generation of such hybrid nanostructures based on non-covalently functionalized CNSs will be reviewed.

  13. Uniform Fe3O4 coating on flower-like ZnO nanostructures by atomic layer deposition for electromagnetic wave absorption.

    PubMed

    Wan, Gengping; Wang, Guizhen; Huang, Xianqin; Zhao, Haonan; Li, Xinyue; Wang, Kan; Yu, Lei; Peng, Xiange; Qin, Yong

    2015-11-21

    An elegant atomic layer deposition (ALD) method has been employed for controllable preparation of a uniform Fe3O4-coated ZnO (ZnO@Fe3O4) core-shell flower-like nanostructure. The Fe3O4 coating thickness of the ZnO@Fe3O4 nanostructure can be tuned by varying the cycle number of ALD Fe2O3. When serving as additives for microwave absorption, the ZnO@Fe3O4-paraffin composites exhibit a higher absorption capacity than the ZnO-paraffin composites. For ZnO@500-Fe3O4, the effective absorption bandwidth below -10 dB can reach 5.2 GHz and the RL values below -20 dB also cover a wide frequency range of 11.6-14.2 GHz when the coating thickness is 2.3 mm, suggesting its potential application in the treatment of the electromagnetic pollution problem. On the basis of experimental observations, a mechanism has been proposed to understand the enhanced microwave absorption properties of the ZnO@Fe3O4 composites.

  14. Study of morphology effects on magnetic interactions and band gap variations for 3d late transition metal bi-doped ZnO nanostructures by hybrid DFT calculations

    NASA Astrophysics Data System (ADS)

    Datta, Soumendu; Kaphle, Gopi Chandra; Baral, Sayan; Mookerjee, Abhijit

    2015-08-01

    Using density functional theory (DFT) based electronic structure calculations, the effects of morphology of semiconducting nanostructures on the magnetic interaction between two magnetic dopant atoms as well as a possibility of tuning band gaps have been studied in the case of the bi-doped (ZnO)24 nanostructures with the impurity dopant atoms of the 3d late transition metals—Mn, Fe, Co, Ni, and Cu. To explore the morphology effect, three different structures of the host (ZnO)24 nano-system, having different degrees of spatial confinement, have been considered: a two dimensional nanosheet, a one dimensional nanotube, and a finite cage-shaped nanocluster. The present study employs hybrid density functional theory to accurately describe the electronic structure of all the systems. It is shown here that the magnetic coupling between the two dopant atoms remains mostly anti-ferromagnetic in the course of changing the morphology from the sheet geometry to the cage-shaped geometry of the host systems, except for the case of energetically most stable bi-Mn doping, which shows a transition from ferromagnetic to anti-ferromagnetic coupling with decreasing aspect ratio of the host system. The effect of the shape change, however, has a significant effect on the overall band gap variations of both the pristine as well as all the bi-doped systems, irrespective of the nature of the dopant atoms and provides a means for easy tunability of their optoelectronic properties.

  15. Effect of different coating layer on the topography and optical properties of ZnO nanostructured

    NASA Astrophysics Data System (ADS)

    Mohamed, R.; Mamat, M. H.; Malek, M. F.; Ismail, A. S.; Yusoff, M. M.; Asiah, M. N.; Khusaimi, Z.; Rusop, M.

    2018-05-01

    Magnesium (Mg) and aluminum (Al) co-doped zinc oxide (MAZO) thin films were synthesized on glass substrate by sol-gel spin coating method. MAZO thin films were prepared at different coating layers range from 1 to 9. Atomic Force Microscopy (AFM) was used to investigate the topography of the thin films. According to the AFM results, Root Means Square (RMS) of MAZO thin films was increased from 0.747 to 6.545 nm, with increase of number coating layer from 1 to 9, respectively. The results shown the variation on structural and topography properties of MAZO seed film when it's deposited at different coating layers on glass substrate. The optical properties was analyzed using UV-Vis spectroscopy. The obtained results show that the transmittance spectra was increased as thin films coating layer increases.

  16. Low-cost and facile synthesis of Ni(OH)2/ZnO nanostructures for high-sensitivity glucose detection

    NASA Astrophysics Data System (ADS)

    Strano, V.; Mirabella, S.

    2018-01-01

    An efficient electrode for non-enzymatic glucose detection is produced with low-cost techniques on a Cu wire. ZnO nanorods (NRs) were grown on a Cu wire by chemical bath deposition and were used as the substrate for pulsed electrodeposition of nanostructured Ni(OH)2 flakes. The effect of the electrodeposition potential on the final morphology and electrochemical behavior of the Ni(OH)2/ZnO/Cu structures is reported. ZnO NRs resulted to be well dressed by Ni(OH)2 flakes and were tested as glucose sensing electrodes in 0.1 M NaOH solution, showing high sensitivities (up to 3 mA mM-1 cm-2) and long-term stability. The presence of ZnO NRs was shown to improve the performance of the glucose sensor in terms of electrochemical stability over the time and sensitivity compared to Ni(OH)2/Cu sample. The reported data demonstrate a simple, versatile and low-cost fabrication approach for effective glucose sensing system within a urban mines framework.

  17. Investigation on the path process of M doped ZnO (M = Gd, Mg) via the sol-gel method from dried gel to stable nanostructure powder

    NASA Astrophysics Data System (ADS)

    Suharno; Soegijono, B.; Budiawanti, S.; Fadillah, L.

    2017-04-01

    Doping is one of the effective methods to modify the physical properties of ZnO material in order to extend its applications. An investigation on Zn1-xMxO (M = Gd, Mg and x = 0.00, 0.03) nanopowders that have been synthesized by sol-gel method and sintered at 600 °C for 2 hours was reported. The decomposition process of the dried gel system was investigated by thermal gravimetric analysis (TGA) and the nanopowders with different heating temperature were studied using FT-IR spectroscopy. The crystal structure of the nanopowders after sintering at 600 °C was obtained using X-ray diffraction (XRD). The TGA curves of the samples showed the various weight loss regions corresponding to the removal of starting materials and no weight loss was observed in the temperature range of 300 to 800 °C which corresponded to the phase-crystallization step. The FTIR spectra showed that ZnO band was assigned to the stretching frequency at 669 cm-1 while Gd/Mg doped ZnO was at 668 cm-1 and 666 cm-1. From the XRD studies, the crystal structure of the samples indicated single phase ZnO crystalline and confirmed hexagonal wurtzite structure (space group of P63mc).

  18. Nanostructured Ti-Ta thin films synthesized by combinatorial glancing angle sputter deposition

    NASA Astrophysics Data System (ADS)

    Motemani, Yahya; Khare, Chinmay; Savan, Alan; Hans, Michael; Paulsen, Alexander; Frenzel, Jan; Somsen, Christoph; Mücklich, Frank; Eggeler, Gunther; Ludwig, Alfred

    2016-12-01

    Ti-Ta alloys are attractive materials for applications in actuators as well as biomedical implants. When fabricated as thin films, these alloys can potentially be employed as microactuators, components for micro-implantable devices and coatings on surgical implants. In this study, Ti100-x Ta x (x = 21, 30) nanocolumnar thin films are fabricated by glancing angle deposition (GLAD) at room temperature using Ti73Ta27 and Ta sputter targets. Crystal structure, morphology and microstructure of the nanostructured thin films are systematically investigated by XRD, SEM and TEM, respectively. Nanocolumns of ˜150-160 nm in width are oriented perpendicular to the substrate for both Ti79Ta21 and Ti70Ta30 compositions. The disordered α″ martensite phase with orthorhombic structure is formed in room temperature as-deposited thin films. The columns are found to be elongated small single crystals which are aligned perpendicular to the (20\\bar{4}) and (204) planes of α″ martensite, indicating that the films’ growth orientation is mainly dominated by these crystallographic planes. Laser pre-patterned substrates are utilized to obtain periodic nanocolumnar arrays. The differences in seed pattern, and inter-seed distances lead to growth of multi-level porous nanostructures. Using a unique sputter deposition geometry consisting of Ti73Ta27 and Ta sputter sources, a nanocolumnar Ti-Ta materials library was fabricated on a static substrate by a co-deposition process (combinatorial-GLAD approach). In this library, a composition spread developed between Ti72.8Ta27.2 and Ti64.4Ta35.6, as confirmed by high-throughput EDX analysis. The morphology over the materials library varies from well-isolated nanocolumns to fan-like nanocolumnar structures. The influence of two sputter sources is investigated by studying the resulting column angle on the materials library. The presented nanostructuring methods including the use of the GLAD technique along with pre-patterning and a

  19. Biologically synthesized titanium oxide nanostructures combined with morphogenetic protein as wound healing agent in the femoral fracture after surgery.

    PubMed

    Zhang, Yushu; Zhang, Chuanlian; Liu, Kemiao; Zhu, Xia; Liu, Fang; Ge, Xiaofen

    2018-05-01

    The aim of the present study is to develop novel approach for the green synthesis of titanium oxide nanoparticles (TiO 2 NPs) using Eichhornia crassipes extract and calcined at different temperatures for evaluate the wound healing activity in the femoral fracture. The synthesized TiO 2 are formed different (plate and rod-like) nanostructures at various calcination temperatures. These samples were characterized by X-ray diffraction (XRD), Fourier transform-infrared spectroscopy (FTIR), Field emission scanning electron microscope (FE-SEM) and transmission electron microscope (TEM). Microscopic studies of TiO 2 NPs revealed that the synthesized TiO 2 NPs are formed well-defined rod-like structures at 400 °C with size ranged from 200 nm to 500 nm. The characterized plate and rod-like TiO 2 NPs are combined with human morphogenetic protein (HbMP) to improving its wound healing activity and osteoblast properties on femoral fractures. The biocompatibility was tested by using human bone marrow mesenchymal stem cells (BMSC) cells and antibacterial efficacy analyzed using human pathogenica bacteria Staphylococcus aureus and Escherichia coli through agar well diffusion assay. The green synthesized rod-like TiO 2 NPs combined with HbMP has been exhibited effective bone fusion behaviors with biomechanical properties and also improved antibacterial activity against pathogenic bacteria. From this study results, it is suggested that green synthesized TiO 2 NPs could be used effectively in biomedical application. Copyright © 2018. Published by Elsevier B.V.

  20. Efficient acetone sensor based on Ni-doped ZnO nanostructures prepared by spray pyrolysis technique

    NASA Astrophysics Data System (ADS)

    Darunkar, Swapnil S.; Acharya, Smita A.

    2018-05-01

    Ni-doped ZnO thin film was prepared by home-built spray pyrolysis unit for the detection of acetone at 300°C. Scanning electron microscopic (SEM) images of as-developed thin film of undoped ZnO exhibits large quantity of spherical, non-agglomerated particles with uniform size while in Ni-doped ZnO, particles are quite non-uniform in nature. The particle size estimated by using image J are obtained to be around 20-200 nm. Ni-doping effect on band gaps are determined by UV-vis optical spectroscopy and band gap of Ni-doped ZnO is found to be 3.046 eV. Nickel doping exceptionally enhances the sensing response of ZnO as compared to undoped ZnO system. The major role of the Ni-doping is to create more active sites for chemisorbed oxygen on the surface of sensor and correspondingly, to improve the sensing response. The 6 at.% of Ni-doped ZnO exhibits the highest response (92%) for 100 ppm acetone at 300 °C.

  1. Solid-state reactions to synthesize nanostructured lead selenide semiconductor powders by high-energy milling

    SciTech Connect

    Rojas-Chavez, H., E-mail: uu_gg_oo@yahoo.com.mx; Reyes-Carmona, F.; Jaramillo-Vigueras, D.

    2011-10-15

    Highlights: {yields} PbSe synthesized from PbO instead of Pb powder do not require an inert atmosphere. {yields} During high-energy milling oxygen has to be chemically reduced from the lead oxide. {yields} Solid-state and solid-gas chemical reactions promote both solid and gaseous products. -- Abstract: Both solid-solid and gas-solid reactions have been traced during high-energy milling of Se and PbO powders under vial (P, T) conditions in order to synthesize the PbSe phase. Chemical and thermodynamic arguments are postulated to discern the high-energy milling mechanism to transform PbO-Se micropowders onto PbSe-nanocrystals. A set of reactions were evaluated at around room temperature.more » Therefore an experimental campaign was designed to test the nature of reactions in the PbO-Se system during high-energy milling.« less

  2. Investigation on structural and electrical properties of Fe doped ZnO nanoparticles synthesized by solution combustion method

    SciTech Connect

    Ram, Mast, E-mail: mastram1999@yahoo.com; Bala, Kanchan; Sharma, Hakikat

    In the present study, nanoparticles of Fe doped zinc oxide (ZnO) [Zn{sub 1-x}Fe{sub x}O where x=0.0, 0.01, 0.02, 0.03 and 0.05] were prepared by cost effective solution combustion method. The powder X-ray diffractometry confirms the formation of single phase wurtzite structure. Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) were used to investigate the micrsostructure of Fe-doped ZnO nanoparticles. The DC electrical conductivity was found to increase with temperature and measurement was carried out in the temperature range of 300-473K. DC electrical conductivity increases with temperature and decreases with Fe doping concentration.

  3. Solid-State Synthesized Nanostructured Au Dendritic Aggregates Towards Surface-Enhanced Raman Spectroscopy

    NASA Astrophysics Data System (ADS)

    Gentile, A.; Ruffino, F.; D'Andrea, C.; Gucciardi, P. G.; Reitano, R.; Grimaldi, M. G.

    2016-06-01

    Micrometric Au structures, presenting a dendritic nano-structure, have been fabricated on a Si-based substrate. The fabrication method involves the deposition of a thin Au film on the substrate and a high-temperature annealing (1100°C) using fast heating and cooling ramps. The thermal process produces the growth, from the substrate, of Si micro-pillars whose top surfaces, covered by a crystalline Au layer, present a nanodendritic morphology. In addition to the micro-pillars, the sample surface presents a complex structural and chemical composition including Si3N4 regions due to the silicon-nitrogen intermixing during the heating stage. By studying the kinetic processes at the Au-Si interface during the thermal treatment, we describe the stages involved in the micro-pillars growth, in the dendritic morphology development, and in the Au atoms entrapment at the top of the dendritic surfaces. Finally, we present the analyses of the optical and surface enhanced Raman scattering properties of the Au dendritic aggregates. We show, in particular, that: (1) the Au dendrites aggregates act as effective scattering elements for the electromagnetic radiation in the infrared spectral region; and (2) the higher surface area due to the branched dendritic structure is responsible for the improvement in the sensitivity of the surface enhanced Raman scattering activity.

  4. ZnO Hierarchical Nanostructure Photoanode in a CdS Quantum Dot-Sensitized Solar Cell

    PubMed Central

    Liu, Huan; Zhang, Gengmin; Sun, Wentao; Shen, Ziyong; Shi, Mingji

    2015-01-01

    A hierarchical array of ZnO nanocones covered with ZnO nanospikes was hydrothermally fabricated and employed as the photoanode in a CdS quantum dot-sensitized solar cell (QDSSC). This QDSSC outperformed the QDSSC based on a simple ZnO nanocone photoanode in all the four principal photovoltaic parameters. Using the hierarchical photoanode dramatically increased the short circuit current density and also slightly raised the open circuit voltage and the fill factor. As a result, the conversion efficiency of the QDSSC based on the hierarchical photoanode was more than twice that of the QDSSC based on the simple ZnO nanocone photoanode. This improvement is attributable to both the enlarged specific area of the photoanode and the reduction in the recombination of the photoexcited electrons. PMID:26379268

  5. Synthesis of ZnO Photocatalysts Using Various Surfactants

    NASA Astrophysics Data System (ADS)

    Yao, Chengli; Zhu, Jinmiao; Li, Hongying; Zheng, Bin; Wei, Yanxin

    2017-12-01

    Zinc oxide (ZnO) nanostructured materials have received significant attention because of their unique physicochemical and electronic properties. In particular, the functional properties of ZnO are owed to its morphology and defect structure. ZnO particles were successfully synthesized by chemical precipitation. CTAB (cetyltrimethylammonium bromide), BS-12 (dodecyl dimethyl betaine) and graphene oxide (GO) were selected as templates to induce the formation of ZnO, respectively. By varying the amount of surfactant added during the synthesis process, the structural properties and the crystalline phase of the synthesized nanospheres were characterized by X-ray powder diffraction (XRD), scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FT-IR), ultraviolet and visible spectrophotometry (UV‒Vis). Simultaneously, photo catalytic degradation of Rhodamine B (RhB) was carried out under natural sunlight irradiation while ZnO or ZnO/GO particles were used as catalyst. GO is prone to induce formation of wurtzite hexagonal phase of ZnO. Compared with CTAB and BS-12, ZnO/GO composites had a remarkably photocatalytic degradation.

  6. Effect of doping on structural, optical and electrical properties of nanostructure ZnO films deposited onto a-Si:H/Si heterojunction

    NASA Astrophysics Data System (ADS)

    Sali, S.; Boumaour, M.; Kermadi, S.; Keffous, A.; Kechouane, M.

    2012-09-01

    We investigated the structural; optical and electrical properties of ZnO thin films as the n-type semiconductor for silicon a-Si:H/Si heterojunction photodiodes. The ZnO film forms the front contact of the super-strata solar cell and has to exhibit good electrical (high conductivity) and optical (high transmittance) properties. In this paper we focused our attention on the influence of doping on device performance. The results show that the X-ray diffraction (XRD) spectra revealed a preferred orientation of the crystallites along c-axis. SEM images show that all films display a granular, polycrystalline morphology and the ZnO:Al exhibits a better grain uniformity. The transmittance of the doped films was found to be higher when compared to undoped ZnO. A low resistivity of the order of 2.8 × 10-4 Ω cm is obtained for ZnO:Al using 0.4 M concentration of zinc acetate. The photoluminescence (PL) spectra exhibit a blue band with two peaks centered at 442 nm (2.80 eV) and 490 nm (2.53 eV). It is noted that after doping the ZnO films a shift of the band by 22 nm (0.15 eV) is recorded and a high luminescence occurs when using Al as a dopant. Dark I-V curves of ZnO/a-Si:H/Si structure showed large difference, which means there is a kind of barrier to current flow between ZnO and a-Si:H layer. Doping films was applied and the turn-on voltages are around 0.6 V. Under reverse bias, the current of the ZnO/a-Si:H/Si heterojunction is larger than that of ZnO:Al/a-Si:H/Si. The improvement with ZnO:Al is attributed to a higher number of generated carriers in the nanostructure (due to the higher transmittance and a higher luminescence) that increases the probability of collisions.

  7. Effects of (Ce, Cu) Co-doping on the Structural and Optical Properties of ZnO Aerogels Synthesized in Supercritical Ethanol

    NASA Astrophysics Data System (ADS)

    Djouadi, D.; Slimi, O.; Hammiche, L.; Chelouche, A.; Touam, T.

    2018-03-01

    Undoped, Ce-doped, Cu-doped and (Ce,Cu ) co-doped ZnO aerogels were synthesized by sol-gel process in supercritical conditions of ethanol. [Cu]/[Zn] and [Ce]/[Zn] atomic ratios were fixed at 0.02 (2%). The aerogels were investigated without any additional treatments by using X-ray diffraction (XRD), UV–visible spectrophotometry, scanning electron microscopy (SEM), Energy-dispersive X-ray spectroscopy (EDS), Fourier transforms infrared spectroscopy (FTIR) and photoluminescence spectroscopy (PL). XRD results revealed that all the samples are well crystallized in hexagonal wurtzite structure. EDS measurements showed that highly pure aerogels are prepared. SEM analysis indicated that the morphology of the samples is dependent on Cu and Ce dopants. From UV-visible spectroscopy analyses, it was shown that the absorption and the band gap of the aerogels are strongly affected by Ce and Cu dopants. FTIR spectra demonstrated that co-doping induces a shift of Zn-O bond vibration band toward low wavenumbers. The room temperature photoluminescence spectra put into evidence that the visible emission intensity is influenced by Ce and Cu doping. In particular, the co-doping leads to the appearance of a blue emission band at 443 nm.

  8. Analysis of ultraviolet photo-response of ZnO nanostructures prepared by electrodeposition and atomic layer deposition

    NASA Astrophysics Data System (ADS)

    Makhlouf, Houssin; Karam, Chantal; Lamouchi, Amina; Tingry, Sophie; Miele, Philippe; Habchi, Roland; Chtourou, Radhouane; Bechelany, Mikhael

    2018-06-01

    In this work, ZnO nanowires (ZnO NWs) and urchin-like ZnO nanowires (U-ZnO NWs) based on self-assembled ordered polystyrene sphere (PS) were successfully prepared by combining atomic layer deposition (ALD) and electrochemical deposition (ECD) processes to build UV photosensors. The photo-response of the prepared samples was investigated and compared. The growth of the nanowires on self-assembled, ordered PS introduces a significant modification on the morphology, crystal orientation and grain size of U-ZnO NWs compared to randomly, vertically aligned ZnO NWs, and therefore improves the photo-response of U-ZnO NWs. The photocurrent may be produced by either a surface or bulk-related process. For ZnO NW-based photosensors, the photocurrent was monitored by a surface related process, whereas, it was mainly governed by a bulk related process for U-ZnO NWs, resulting in a higher and faster photo-response. The study of the rise and decay time constants for both materials showed that these parameters were strikingly sensitive to the optical properties.

  9. Sol concentration effect on ZnO nanofibers photocatalytic activity synthesized by sol-gel dip coating method

    NASA Astrophysics Data System (ADS)

    Toubane, M.; Tala-Ighil, R.; Bensouici, F.; Bououdina, M.; Souier, M.; Liu, S.; Cai, W.; Iratni, A.

    2017-03-01

    ZnO thin films were deposited onto glass substrate by sol-gel dip coating method. The initial sol concentrations were varied from 0.2 to 0.5 M. Zinc acetate dihydrate, ethanol and Diethanolamine (DEA) were used as staring material, solvent and stabilizer respectively. The evolution of structural, optical properties and methylene blue (MB) photodegradation of the as-deposited films on sol concentration was investigated. Rietveld refinements of x-ray patterns reveal that all the as-prepared thin films have a Zincite-type structure with grain orientation along to c-axis. The strongest sol concentration is favorable for the highest crystallization quality. However, the high preferred orientation factor (POF) occurs for 0.3 M sol concentration. The field emission scanning electron microscopy observations reveals nanofibrous morphology with different lengths. The nanofibers density increases with increasing sols concentrations until forming a flower-like morphology. The EDS analysis confirms the high purity of the as-deposited ZnO films. It is found that all films present good transparency greater than 95% in the visible range; the optical band gap is slightly reduced with the increase in sol concentration. The photocatalytic degradation is enhanced by 90% with the sol concentration. The K app rate reaction increased with increasing sol concentration. The films stability is found to slightly decrease after the third cycle, especially for 0.5 M sol concentration.

  10. One-pot ultrasonic-assisted method for preparation of Ag/AgCl sensitized ZnO nanostructures as visible-light-driven photocatalysts

    NASA Astrophysics Data System (ADS)

    Naghizadeh-Alamdari, Sara; Habibi-Yangjeh, Aziz; Pirhashemi, Mahsa

    2015-02-01

    Ultrasonic-assisted method was applied for preparation of Ag/AgCl sensitized ZnO nanostructures by one-pot procedure in water without using any post preparation treatments. The resultant nanocomposites were characterized by XRD, EDX, SEM, DRS, XPS, BET, and PL techniques. In the nanocomposites, ZnO and AgCl have wurtzite hexagonal and cubic crystalline phases, respectively and their surface morphologies remarkably change with increasing mole fraction of silver chloride. The EDX and XPS techniques show that the prepared samples are extremely pure. Ability of the nanocomposites for absorption of visible-light irradiation enhanced with increasing AgCl content. Photocatalytic examination of the nanocomposites was carried out using aqueous solution of methylene blue under visible-light irradiation. The degradation rate constant on the nancomposite rapidly increases with mole fraction of silver chloride up to 0.237. Enhancing activity of the nanocomposite was attributed to its ability for absorbing visible light and separation of electron-hole pairs. Furthermore, influence of ultrasonic irradiation time, calcination temperature, catalyst weight, pH of solution, and scavengers of reactive species on the degradation activity was investigated and the results were discussed. Finally, the photocatalyst has good activity after five successive cycles.

  11. Sonochemical Synthesis of Zinc Oxide Nanostructures for Sensing and Energy Harvesting

    NASA Astrophysics Data System (ADS)

    Vabbina, Phani Kiran

    Semiconductor nanostructures have attracted considerable research interest due to their unique physical and chemical properties at nanoscale which open new frontiers for applications in electronics and sensing. Zinc oxide nanostructures with a wide range of applications, especially in optoelectronic devices and bio sensing, have been the focus of research over the past few decades. However ZnO nanostructures have failed to penetrate the market as they were expected to, a few years ago. The two main reasons widely recognized as bottleneck for ZnO nanostructures are (1) Synthesis technique which is fast, economical, and environmentally benign which would allow the growth on arbitrary substrates and (2) Difficulty in producing stable p-type doping. The main objective of this research work is to address these two bottlenecks and find a solution that is inexpensive, environmentally benign and CMOS compatible. To achieve this, we developed a Sonochemical method to synthesize 1D ZnO Nanorods, core-shell nanorods, 2D nanowalls and nanoflakes on arbitrary substrates which is a rapid, inexpensive, CMOS compatible and environmentally benign method and allows us to grow ZnO nanostructures on any arbitrary substrate at ambient conditions while most other popular methods used are either very slow or involve extreme conditions such as high temperatures and low pressure. A stable, reproducible p-type doping in ZnO is one of the most sought out application in the field of optoelectronics. Here in this project, we doped ZnO nanostructures using sonochemical method to achieve a stable and reproducible doping in ZnO. We have fabricated a homogeneous ZnO radial p-n junction by growing a p-type shell around an n-type core in a controlled way using the sonochemical synthesis method to realize ZnO homogeneous core-shell radial p-n junction for UV detection. ZnO has a wide range of applications from sensing to energy harvesting. In this work, we demonstrate the successful fabrication of an

  12. Ultrafast Formation of ZnO Nanorods via Seed-Mediated Microwave Assisted Hydrolysis Process

    NASA Astrophysics Data System (ADS)

    Tan, S. T.; Umar, A. A.; Yahaya, M.; Yap, C. C.; Salleh, M. M.

    2013-04-01

    One dimensional (1D) zinc oxide, ZnO nanostructures have shown promising results for usage in photodiode and optoelectronic device due to their high surface area. Faster and conventional method for synthesis ZnO nanorods has become an attention for researcher today. In this paper, ZnO nanorods have been successfully synthesized via two-step process, namely alcothermal seeding and seed-mediated microwave hydrolysis process. In typical process, the ZnO nanoseeds were grown in the growth solution that contained equimolar (0.04 M) of zinc nitrate hexahydrate, Zn (NO3).6H2O and hexamethylenetetramine, HMT. The growth process was carried inside the inverted microwave within 5- 20 s. The effect of growth parameters (i.e. concentration, microwave power, time reaction) upon the modification of ZnO morphology was studied. ZnO nanostructures were characterized by Field emission scanning electron microscope (FESEM) and X-ray diffraction (XRD). The densities of nanorods were evaluated by the Image J analysis. It was found that the morphology (e.g. shape and size) of nanostructures has changed drastically with the increment of growth solution concentration. The density of ZnO nanorods was proven to increase with the increasing of reaction time and microwave power. We hypothesize that the microwave power might enhance the rate of nucleation and promote the faster nanostructure growth as compared with the normal heating condition due to the superheating phenomenon. This method might promote a new and faster alternative way in nanostructure growth which can be applied in currently existing application.

  13. Supercapacitive behaviors and their temperature dependence of sol-gel synthesized nanostructured manganese dioxide in lithium hydroxide electrolyte

    NASA Astrophysics Data System (ADS)

    Wang, Xiuling; Yuan, Anbao; Wang, Yuqin

    In the present work, a nanostructured manganese dioxide material was synthesized by a sol-gel method starting with manganese acetate (MnAc 2·4H 2O) and citric acid (C 6H 8O 7·H 2O) raw materials, and characterized by X-ray diffraction, infrared spectroscopic and transmission electron microscope techniques. The electrochemical properties and the influence of temperature on supercapacitive behaviors of the nano-MnO 2 electrode in 1 M LiOH electrolyte were investigated using electrochemical methods. Experimental results show that the MnO 2 electrode can exhibit an excellent pseudocapacitive behavior in 1 M LiOH electrolyte, and a high specific capacitance of 317 F g -1 can be obtained at a charge/discharge current rate of 100 mA g -1 and at the temperature of 25 °C. We found that temperature has a crucial influence on the discharge specific capacitance of the electrode. The specific capacitance at 25 °C is higher than that at 15 or 35 °C.

  14. Optical, electrical and magnetic properties of nanostructured Mn3O4 synthesized through a facile chemical route

    NASA Astrophysics Data System (ADS)

    Bose, Vipin C.; Biju, V.

    2015-02-01

    Nanostructured Mn3O4 sample with an average crystallite size of ˜15 nm is synthesized via the reduction of potassium permanganate using hydrazine. The average particle size obtained from the Transmission Electron Microscopy analysis is in good agreement with the average crystallite size estimated from X-ray diffraction analysis. The presence of Mn4+ ions at the octahedral sites is inferred from the results of Raman, UV-visible absorption and X-ray photoelectron spectroscopy analyzes. DC electrical conductivity of the sample in the temperature range 313-423 K, is about five orders of magnitude larger than that reported for single crystalline Mn3O4 sample. The dominant conduction mechanism is identified to be of the polaronic hopping of holes between cations in the octahedral sites. The zero field cooled and field cooled magnetization of the sample is studied in the range 20-300 K. The Curie temperature for the sample is about 45 K, below which the sample is ferrimagnetic. A blocking temperature of 35 K is observed in the field cooled curve. It is observed that the sample shows hysteresis at temperatures below the Curie temperature with no saturation, even at an applied field (20 kOe). The presence of an ordered core and disordered surface of spin arrangements is observed from the magnetization studies. Above the Curie temperature, the sample shows linear dependence of magnetization on applied field with no hysteresis characteristic of paramagnetic phase.

  15. Highly Sensitive and Selective Ethanol Sensor Fabricated with In-Doped 3DOM ZnO.

    PubMed

    Wang, Zhihua; Tian, Ziwei; Han, Dongmei; Gu, Fubo

    2016-03-02

    ZnO is an important n-type semiconductor sensing material. Currently, much attention has been attracted to finding an effective method to prepare ZnO nanomaterials with high sensing sensitivity and excellent selectivity. A three-dimensionally ordered macroporous (3DOM) ZnO nanostructure with a large surface area is beneficial to gas and electron transfer, which can enhance the gas sensitivity of ZnO. Indium (In) doping is an effective way to improve the sensing properties of ZnO. In this paper, In-doped 3DOM ZnO with enhanced sensitivity and selectivity has been synthesized by using a colloidal crystal templating method. The 3DOM ZnO with 5 at. % of In-doping exhibits the highest sensitivity (∼88) to 100 ppm ethanol at 250 °C, which is approximately 3 times higher than that of pure 3DOM ZnO. The huge improvement to the sensitivity to ethanol was attributed to the increase in the surface area and the electron carrier concentration. The doping by In introduces more electrons into the matrix, which is helpful for increasing the amount of adsorbed oxygen, leading to high sensitivity. The In-doped 3DOM ZnO is a promising material for a new type of ethanol sensor.

  16. Synthesis, Dielectric, Electrical and Optical characterization of ZnO synthesized by chemical route using polymer precursors

    NASA Astrophysics Data System (ADS)

    Mishra, Raman; Bajpai, P. K.

    2011-11-01

    Nano-size ZnO (particle size 7.8 nm) have been prepared from a versatile, efficient and technically simple polymer matrix based precursor solution. The precursor solution constituted of zinc nitrates with polymer PVA in presence of mono-/disaccharides. Annealing the precursor mass at 900 °C single phase zinc oxide nano-particles are obtained. X-ray diffraction analysis confirms hexagonal crystal structure with lattice parameter a = b = 3.261 A0, c = 5.220 A0. The estimated average particle size obtained from XRD data is ≈7.8 nm. The impedance analysis reveals that the grain resistance decreases with increase in temperature as expected for a semi-conducting material. The relaxation is polydispersive and conduction is mainly through grains. Optical properties and AC/DC conduction activation energies are estimated from Arrhenius plots and conduction mechanism is discussed.

  17. A new approach to synthesize ZnO tetrapod-like nanoparticles with DC thermal plasma technique

    NASA Astrophysics Data System (ADS)

    Lin, Hsiu-Fen; Liao, Shih-Chieh; Hu, Chen-Ti

    2009-02-01

    The feasibility of fabricating the tetrapod-like zinc oxide (TZ) nanoparticles with a DC thermal plasma reactor was demonstrated in the present study. Advantages of this process include the low cost and high yield rate (0.8-1.0 kg/h) in producing high TZ content mixtures (with small portion of rod-like zinc oxide (RZ) and plate-like zinc oxide (PZ) nanoparticles) from commercial metal zinc powders. ZnO nanopowders with high TZ content could be employed as the starting material for photocatalytic filters. The ratio of TZ to RZ and PZ in the products was observed to be strongly influenced by the plasma power and the plasma gas flow rate. The optical spectrum, photostability and anti-microbial property of the as-grown and annealed TZ mixtures were examined and compared in this study.

  18. ZnO nanostructures directly grown on paper and bacterial cellulose substrates without any surface modification layer.

    PubMed

    Costa, Saionara V; Gonçalves, Agnaldo S; Zaguete, Maria A; Mazon, Talita; Nogueira, Ana F

    2013-09-21

    In this report, hierarchical ZnO nano- and microstructures were directly grown for the first time on a bacterial cellulose substrate and on two additional different papers by hydrothermal synthesis without any surface modification layer. Compactness and smoothness of the substrates are two important parameters that allow the growth of oriented structures.

  19. Room-temperature synthesis of carnation-like ZnO@AgI hierarchical nanostructures assembled by AgI nanoparticles-decorated ZnO nanosheets with enhanced visible light photocatalytic activity.

    PubMed

    Huang, He; Huang, Ni; Wang, Zhonghua; Xia, Guangqiang; Chen, Ming; He, Lingling; Tong, Zhifang; Ren, Chunguang

    2017-09-15

    The preparation of highly efficient visible-light-driven photocatalyst for the photodegradation of organic pollutants has received much attention due to the increasing global energy crises and environmental pollution. In this study, carnation-like ZnO@AgI hierarchical nanostructures assembled by AgI nanoparticles-decorated ZnO nanosheets were successfully prepared via a room-temperature route. The as-prepared ZnO@AgI nanostructures exhibited highly efficient photocatalytic activity under visible light irradiation (λ>400nm). Under optimized AgI content, the ZnO@AgI-5% sample showed high photocatalytic activity, which was 25.7 and 1.5 times the activity of pure ZnO and pure AgI, respectively. Mechanism studies indicated that superoxide anion radicals (O 2 - ) was the main reactive species in the photocatalytic process. The high photocatalytic activity of the ZnO@AgI nanostructures is attributed to the highly active AgI nanoparticles and the heterojunction between AgI nanoparticles and ZnO nanosheets. The heterojunction structure reduced the recombination of the photogenerated electron-hole pairs in the conduction band (CB) and valence band (VB) of AgI nanoparticles by transferring the electrons from the CB of AgI nanoparticles to the CB of ZnO nanosheets. The composite of ZnO and AgI not only improves photocatalytic efficiency but also reduces photocatalyst cost, which is beneficial for practical application. Copyright © 2017 Elsevier Inc. All rights reserved.

  20. Harmonizing HeLa cell cytoskeleton behavior by multi-Ti oxide phased nanostructure synthesized through ultrashort pulsed laser

    PubMed Central

    Chinnakkannu Vijayakumar, Chandramouli; Venkatakrishnan, Krishnan; Tan, Bo

    2015-01-01

    Knowledge about cancer cell behavior on heterogeneous nanostructures is relevant for developing a distinct biomaterial that can actuate cancer cells. In this manuscript, we have demonstrated a harmonized approach of forming multi Ti-oxide phases in a nanostructure (MTOP nanostructure) for its unique cancer cell controlling behavior.Conventionally, single phases of TiO2 are used for targeted therapy and as drug carrier systems.In this research, we have shown a biomaterial that can control HeLa cells diligently using a combination of TiO, Ti3O and TiO2 phases when compared to fibroblast (NIH3T3) cells.MTOP-nanostructures are generated by varying the ionization energy in the vapor plume of the ultrashort pulse laser; this interaction with the material allows accurate tuning and composition of phases within the nanostructure. In addition, the lattice spacing of MTOP-nanostructures was analyzed as shown by HR-TEM investigations. An FESEM investigation of MTOP-nanostructures revealed a greater reduction of HeLa cells relative to fibroblast cells. Altered cell adhesion was followed by modulation of HeLa cell architecture with a significant reduction of actin stress fibers.The intricate combination of MTOP-nanostructures renders a biomaterial that can precisely alter HeLa cell but not fibroblast cell behavior, filling a void in the research for a biomaterial to modulate cancer cell behavior. PMID:26469886

  1. Harmonizing HeLa cell cytoskeleton behavior by multi-Ti oxide phased nanostructure synthesized through ultrashort pulsed laser

    NASA Astrophysics Data System (ADS)

    Chinnakkannu Vijayakumar, Chandramouli; Venkatakrishnan, Krishnan; Tan, Bo

    2015-10-01

    Knowledge about cancer cell behavior on heterogeneous nanostructures is relevant for developing a distinct biomaterial that can actuate cancer cells. In this manuscript, we have demonstrated a harmonized approach of forming multi Ti-oxide phases in a nanostructure (MTOP nanostructure) for its unique cancer cell controlling behavior.Conventionally, single phases of TiO2 are used for targeted therapy and as drug carrier systems.In this research, we have shown a biomaterial that can control HeLa cells diligently using a combination of TiO, Ti3O and TiO2 phases when compared to fibroblast (NIH3T3) cells.MTOP-nanostructures are generated by varying the ionization energy in the vapor plume of the ultrashort pulse laser; this interaction with the material allows accurate tuning and composition of phases within the nanostructure. In addition, the lattice spacing of MTOP-nanostructures was analyzed as shown by HR-TEM investigations. An FESEM investigation of MTOP-nanostructures revealed a greater reduction of HeLa cells relative to fibroblast cells. Altered cell adhesion was followed by modulation of HeLa cell architecture with a significant reduction of actin stress fibers.The intricate combination of MTOP-nanostructures renders a biomaterial that can precisely alter HeLa cell but not fibroblast cell behavior, filling a void in the research for a biomaterial to modulate cancer cell behavior.

  2. Different valence Sn doping - A simple way to detect oxygen concentration variation of ZnO quantum dots synthesized under ultrasonic irradiation.

    PubMed

    Yang, Weimin; Zhang, Bing; Zhang, Qitu; Wang, Lixi; Song, Bo; Wu, Fan; Wong, C P

    2017-09-01

    An ultrasonic method is employed to synthesize the Sn doped Zn 0.95 Sn 0.05 O quantum dots with green light emission. Sn 2+ and Sn 4+ ions are used to create different optical defects inside Zn 0.95 Sn 0.05 O quantum dots and the changing trend of oxygen concentration under different ultrasonic irradiation power are investigated. The photoluminescence spectra are employed to characterize the optical defects of Zn 0.95 Sn 0.05 O quantum dots. The UV-vis spectra are used to study the band gap of Zn 0.95 Sn 0.05 O quantum dots, which is influenced by their sizes. The results indicate that ultrasonic power would influence the size of Zn 0.95 Sn 0.05 O quantum dots as well as the type and quantity of defects in ZnO quantum dots. Changing trends in size of Sn 2+ and Sn 4+ doped Zn 0.95 Sn 0.05 O quantum dots are quite similar with each other, while the changing trends in optical defects types and concentration of Sn 2+ and Sn 4+ doped Zn 0.95 Sn 0.05 O quantum dots are different. The difference of the optical defects concentration changing between Sn 2+ doped Zn 0.95 Sn 0.05 O quantum dots (V O defects) and Sn 4+ doped Zn 0.95 Sn 0.05 O quantum dots (O Zn and O i defects) shows that the formation process of ZnO under ultrasonic irradiation wiped oxygen out. Copyright © 2017 Elsevier B.V. All rights reserved.

  3. Statistical optimization and artificial neural network modeling for acridine orange dye degradation using in-situ synthesized polymer capped ZnO nanoparticles.

    PubMed

    Dhiman, Nitesh; Markandeya; Singh, Amrita; Verma, Neeraj K; Ajaria, Nidhi; Patnaik, Satyakam

    2017-05-01

    ZnO NPs were synthesized by a prudent green chemistry approach in presence of polyacrylamide grafted guar gum polymer (pAAm-g-GG) to ensure uniform morphology, and functionality and appraised for their ability to degrade photocatalytically Acridine Orange (AO) dye. These ZnO@pAAm-g-GG NPs were thoroughly characterized by various spectroscopic, XRD and electron microscopic techniques. The relative quantity of ZnO NPs in polymeric matrix has been estimated by spectro-analytical procedure; AAS and TGA analysis. The impact of process parameters viz. NP's dose, contact time and AO dye concentration on percentage photocatalytic degradation of AO dyes were evaluated using multivariate optimizing tools, Response Surface Methodology (RSM) involving Box-Behnken Design (BBD) and Artificial Neural Network (ANN). Congruity of the BBD statistical model was implied by R 2 value 0.9786 and F-value 35.48. At RSM predicted optimal condition viz. ZnO@pAAm-g-GG NP's dose of 0.2g/L, contact time of 210min and AO dye concentration 10mg/L, a maximum of 98% dye degradation was obtained. ANOVA indicated appropriateness of the model for dye degradation owing to "Prob.>F" less than 0.05 for variable parameters. We further, employed three layers feed forward ANN model for validating the BBD process parameters and suitability of our chosen model. The evaluation of Levenberg-Marquardt algorithm (ANN1) and Gradient Descent with adaptive learning rate (ANN2) model employed to scrutinize the best method and found experimental values of AO dye degradation were in close to those with predicated value of ANN 2 modeling with minimum error. Copyright © 2017 Elsevier Inc. All rights reserved.

  4. Realizing a facile and environmental-friendly fabrication of high-performance multi-crystalline silicon solar cells by employing ZnO nanostructures and an Al2O3 passivation layer

    NASA Astrophysics Data System (ADS)

    Chen, Hong-Yan; Lu, Hong-Liang; Sun, Long; Ren, Qing-Hua; Zhang, Hao; Ji, Xin-Ming; Liu, Wen-Jun; Ding, Shi-Jin; Yang, Xiao-Feng; Zhang, David Wei

    2016-12-01

    Nowadays, the multi-crystalline silicon (mc-Si) solar cells dominate the photovoltaic industry. However, the current acid etching method on mc-Si surface used by firms can hardly suppress the average reflectance value below 25% in the visible light spectrum. Meanwhile, the nitric acid and the hydrofluoric contained in the etching solution is both environmental unfriendly and highly toxic to human. Here, a mc-Si solar cell based on ZnO nanostructures and an Al2O3 spacer layer is demonstrated. The eco-friendly fabrication is realized by low temperature atomic layer deposition of Al2O3 layer as well as ZnO seed layer. Moreover, the ZnO nanostructures are prepared by nontoxic and low cost hydro-thermal growth process. Results show that the best passivation quality of the n+ -type mc-Si surface can be achieved by balancing the Si dangling bond saturation level and the negative charge concentration in the Al2O3 film. Moreover, the average reflectance on cell surface can be suppressed to 8.2% in 400-900 nm range by controlling the thickness of ZnO seed layer. With these two combined refinements, a maximum solar cell efficiency of 15.8% is obtained eventually. This work offer a facile way to realize the environmental friendly fabrication of high performance mc-Si solar cells.

  5. Realizing a facile and environmental-friendly fabrication of high-performance multi-crystalline silicon solar cells by employing ZnO nanostructures and an Al2O3 passivation layer

    PubMed Central

    Chen, Hong-Yan; Lu, Hong-Liang; Sun, Long; Ren, Qing-Hua; Zhang, Hao; Ji, Xin-Ming; Liu, Wen-Jun; Ding, Shi-Jin; Yang, Xiao-Feng; Zhang, David Wei

    2016-01-01

    Nowadays, the multi-crystalline silicon (mc-Si) solar cells dominate the photovoltaic industry. However, the current acid etching method on mc-Si surface used by firms can hardly suppress the average reflectance value below 25% in the visible light spectrum. Meanwhile, the nitric acid and the hydrofluoric contained in the etching solution is both environmental unfriendly and highly toxic to human. Here, a mc-Si solar cell based on ZnO nanostructures and an Al2O3 spacer layer is demonstrated. The eco-friendly fabrication is realized by low temperature atomic layer deposition of Al2O3 layer as well as ZnO seed layer. Moreover, the ZnO nanostructures are prepared by nontoxic and low cost hydro-thermal growth process. Results show that the best passivation quality of the n+ -type mc-Si surface can be achieved by balancing the Si dangling bond saturation level and the negative charge concentration in the Al2O3 film. Moreover, the average reflectance on cell surface can be suppressed to 8.2% in 400–900 nm range by controlling the thickness of ZnO seed layer. With these two combined refinements, a maximum solar cell efficiency of 15.8% is obtained eventually. This work offer a facile way to realize the environmental friendly fabrication of high performance mc-Si solar cells. PMID:27924911

  6. Nonequilibrium-Plasma-Synthesized ZnO Nanocrystals with Plasmon Resonance Tunable via Al Doping and Quantum Confinement.

    PubMed

    Greenberg, Benjamin L; Ganguly, Shreyashi; Held, Jacob T; Kramer, Nicolaas J; Mkhoyan, K Andre; Aydil, Eray S; Kortshagen, Uwe R

    2015-12-09

    Metal oxide semiconductor nanocrystals (NCs) exhibit localized surface plasmon resonances (LSPRs) tunable within the infrared (IR) region of the electromagnetic spectrum by vacancy or impurity doping. Although a variety of these NCs have been produced using colloidal synthesis methods, incorporation and activation of dopants in the liquid phase has often been challenging. Herein, using Al-doped ZnO (AZO) NCs as an example, we demonstrate the potential of nonthermal plasma synthesis as an alternative strategy for the production of doped metal oxide NCs. Exploiting unique, thoroughly nonequilibrium synthesis conditions, we obtain NCs in which dopants are not segregated to the NC surfaces and local doping levels are high near the NC centers. Thus, we achieve overall doping levels as high as 2 × 10(20) cm(-3) in NCs with diameters ranging from 12.6 to 3.6 nm, and for the first time experimentally demonstrate a clear quantum confinement blue shift of the LSPR energy in vacancy- and impurity-doped semiconductor NCs. We propose that doping of central cores and heavy doping of small NCs are achievable via nonthermal plasma synthesis, because chemical potential differences between dopant and host atoms-which hinder dopant incorporation in colloidal synthesis-are irrelevant when NC nucleation and growth proceed via irreversible interactions among highly reactive gas-phase ions and radicals and ligand-free NC surfaces. We explore how the distinctive nucleation and growth kinetics occurring in the plasma influences dopant distribution and activation, defect structure, and impurity phase formation.

  7. Antimicrobial activity of ZnO-TiO2 nanomaterials synthesized from three different precursors of ZnO: influence of ZnO/TiO2 weight ratio.

    PubMed

    Daou, Ikram; Moukrad, Najia; Zegaoui, Omar; Rhazi Filali, Fouzia

    2018-03-01

    In this study, ZnO-TiO 2 nanoparticles were synthesized from three different precursors for ZnO (zinc acetate di-hydrate, zinc nitrate hexahydrate and zinc sulfate heptahydrate) and titanium (IV) isopropoxide for TiO 2 . The prepared nanomaterials were calcined at 500 °C for 3 h and characterized by various physicochemical techniques such as X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR) and transmission electron microscopy, combined with energy dispersive X-ray spectroscopy (TEM-EDS). The obtained results showed that the crystalline structure, size and morphology of the ZnO-TiO 2 nanoparticles are strongly influenced by the nature of the precursor of ZnO, as well as the ZnO/TiO 2 weight ratio. The antibacterial and antifungal activities of the synthesized nanomaterials were evaluated, in the dark, against five multi-resistant of Gram positive (Staphylococcus aureus) and Gram negative (Escherichia coli, Klebsiella pneumoniae, Pseudomonas aeruginosa and Salmonella Paratyphi A) bacteria and a fungus (Candida albicans), which are pathogenic for humans. The obtained results showed that pure TiO 2 anatase is inactive against the tested strains, while the addition of ZnO to TiO 2 improves noticeably the effectiveness of TiO 2 nanoparticles, depending on the nature of the precursor of ZnO and the ZnO/TiO 2 weight ratio.

  8. Mesoporous Co3O4 nanostructured material synthesized by one-step soft-templating: A magnetic study

    NASA Astrophysics Data System (ADS)

    Poyraz, Altug S.; Hines, William A.; Kuo, Chung-Hao; Li, Nan; Perry, David M.; Suib, Steven L.

    2014-03-01

    A combined magnetization and zero-field 59Co spin-echo nuclear magnetic resonance (NMR) study has been carried out on one member of a recently developed class of highly ordered mesoporous nanostructured materials, mesoporous Co3O4 (designated UCT-8, University of Connecticut, mesoporous materials). The material was synthesized using one-step soft-templating by an inverse micelles packing approach. Characterization of UCT-8 by powder x-ray diffraction and electron microscopy reveals that the mesostructure consists of random close-packed Co3O4 nanoparticles ≈ 12 nm in diameter. The N2 sorption isotherm for UCT-8, which is type IV with a type H1 hysteresis loop, yields a 134 m2/g BET surface area and a 7.7 nm BJH desorption pore diameter. The effect of heat treatment on the structure is discussed. The antiferromagnetic Co3O4 nanoparticles have a Néel temperature TN = 27 K, somewhat lower than the bulk. A fit to the Curie-Weiss law over the temperature range 75 K ≤ T ≤ 300 K yields an effective magnetic moment of μeff = 4.36 μB for the Co2+ ions, indicative of some orbital contribution, and a Curie-Weiss temperature Θ = -93.5 K, consistent with antiferromagnetic ordering. The inter-sublattice and intra-sublattice exchange constants for the Co2+ ions are J1/kB = (-)4.75 K and J2/kB = (-)0.87 K, respectively, both corresponding to antiferromagnetic coupling. The presence of uncompensated surface spins is observed below TN with shifts in the hysteresis loops, i.e., an exchange-bias effect. The 59Co NMR spectrum for UCT-8, which is attributed to Co2+ ions at the tetrahedral A sites, is asymmetrically broadened with a peak at ≈55 MHz (T = 4.2 K). Since there is cubic symmetry at the A-sites, the broadening is indicative of a magnetic field distribution due to the uncompensated surface spins. The spectrum is consistent with antiferromagnetically ordered particles that are nanometer in size and single domain.

  9. Seed layer effect on different properties and UV detection capability of hydrothermally grown ZnO nanorods over SiO2/p-Si substrate

    NASA Astrophysics Data System (ADS)

    Sannakashappanavar, Basavaraj S.; Byrareddy, C. R.; Kumar, Pesala Sudheer; Yadav, Aniruddh Bahadur

    2018-05-01

    Hydrothermally grown one dimensional ZnO nanostructures are among the most widely used semiconductor materials to build high-efficiency electronic devices for various applications. Few researchers have addressed the growth mechanism and effect of ZnO seed layer on different properties of ZnO nanorods grown by hydrothermal method, instead, no one has synthesized ZnO nanorod over SiO2/p-Si substrate. The aim of this study is to study the effect of ZnO seed layer and the growth mechanism of ZnO nanorods over SiO2/p-Si substrate. To achieve the goal, we have synthesized ZnO nanorods over different thickness ZnO seed layers by using the hydrothermal method on SiO2/p-Si substrate. The effects of c-plane area ratio were identified for the growth rate of c-plane, reaction rate constant and stagnant layer thickness also calculated by using a modified rate growth equation. We have identified maximum seed layer thickness for the growth of vertical ZnO nanorod. A step dislocation in the ZnO nanorods grown on 150and 200 nm thick seed layers was observed, the magnitude of Burges vector was calculated for this disorder. The seed layer and ZnO nanorods were characterized by AFM, XPS, UV-visible, XRD (X-ray diffraction, and SEM(scanning electron microscope). To justify the application of the grown ZnO nanorods Ti/Au was deposited over ZnO nanorods grown over all seed layers for the fabrication of photoconductor type UV detector.

  10. Role of ZnO photoanode nanostructures and sensitizer deposition approaches on the photovoltaic properties of CdS/CdSe and CdS1-xSex quantum dot-sensitized solar cells

    NASA Astrophysics Data System (ADS)

    Şişman, İlkay; Tekir, Oktay; Karaca, Hüseyin

    2017-02-01

    Hierarchical bundle-like ZnO nanorod arrays (BNRs) were synthesized by a one-pot hydrothermal method based on two consecutive temperature steps for cascade CdS/CdSe and ternary CdS1-xSex alloy quantum dot-sensitized solar cells (QDSSCs) as photoanode. The CdS/CdSe and CdS1-xSex QDs were deposited on the surface of the ZnO BNRs by conventional and modified successive ionic-layer adsorption and reaction (SILAR) methods, respectively. Using the ZnO BNRs/CdS/CdSe photoanode, the power conversion efficiency reaches 2.08%, which is 1.8 times higher than that of pristine ZnO nanorods/CdS/CdSe photoanode, while by applying ZnO BNRs/CdS1-xSex, the power conversion efficiency improves 2.52%. The remarkably improved photovoltaic performance is mainly derived from the bundle-like nanorod arrays structure, which increases the QDs loading amount and the scattering effect for light absorption, and the appropriate conduction band energy, sufficient Se amount and well coverage of the ternary CdS1-xSex QDs result in enhanced photogenerated electron injection, high light absorption and reduced recombination, respectively. As a result, ZnO BNRs/CdS1-xSex combination can significantly improve performance of QDSSCs.

  11. Nanoparticle Self-Assembled Grain Like Curcumin Conjugated ZnO: Curcumin Conjugation Enhances Removal of Perylene, Fluoranthene, and Chrysene by ZnO

    PubMed Central

    Moussawi, Rasha N.; Patra, Digambara

    2016-01-01

    Curcumin conjugated ZnO, referred as Zn(cur)O, nanostructures have been successfully synthesized, these sub-micro grain-like structures are actually self-assemblies of individual needle-shaped nanoparticles. The nanostructures as synthesized possess the wurtzite hexagonal crystal structure of ZnO and exhibit very good crystalline quality. FT-Raman and TGA analysis establish that Zn(cur)O is different from curcumin anchored ZnO (ZnO@cur), which is prepared by physically adsorbing curcumin on ZnO surfaces. Chemically Zn(cur)O is more stable than ZnO@cur. Diffuse reflectance spectroscopy indicates Zn(cur)O have more impurities compared to ZnO@cur. The solid-state photoluminescence of Zn(cur)O has been investigated, which demonstrates that increase of curcumin concentration in Zn(cur)O suppresses visible emission of ZnO prepared through the same method, this implies filling ZnO defects by curcumin. However, at excitation wavelength 425 nm the emission is dominated by fluorescence from curcumin. The study reveals that Zn(cur)O can remove to a far extent high concentrations of perylene, fluoranthene, and chrysene faster than ZnO. The removal depends on the extent of curcumin conjugation and is found to be faster for PAHs having smaller number of aromatic rings, particularly, it is exceptional for fluoranthene with 93% removal after 10 minutes in the present conditions. The high rate of removal is related to photo-degradation and a mechanism has been proposed. PMID:27080002

  12. Structural, Optical, and Photocatalytic Properties of Quasi-One-Dimensional Nanocrystalline ZnO, ZnOC:nC Composites, and C-doped ZnO

    NASA Astrophysics Data System (ADS)

    Shalaeva, E. V.; Gyrdasova, O. I.; Krasilnikov, V. N.; Melkozerova, M. A.; Baklanova, I. V.; Buldakova, L. Yu.

    Various thermolysis rotes of zinc glicolate complexes are considered for the synthesis of quasi-one-dimensional nanostructured aggregates ZnO and Zn-O-C used as photocatalysts. Structural features of quasi-one-dimensional aggregates Zn-O-C and ZnO are investigated in detail. Transmission electron microscopy, Raman spectroscopy, and electron paramagnetic resonance spectroscopy methods demonstrate that the aggregates Zn-O-C have either composite structure (ZnO crystallites in amorphous carbon matrix) or a C-doped ZnO single-phase structure depending on heat treatment conditions, and that all the aggregates exhibit as a rule a tubular morphology, a nanocrystalline structure with a high specific surface area, and a high concentration of singly charged oxygen vacancies. The mechanism of the nanocrystalline structure formation is discussed and the effect of thermolysis condition on the formation of the textured structure of aggregates is investigated. The results of examination of the photocatalytic and optical absorption properties of the synthesized aggregates are presented. The photocatalytic activity for the hydroquinone oxidation reaction under ultraviolet and visible light increases in the series: the reference ZnO powder, quasi-one-dimensional ZnO, quasi-one-dimensional aggregates C-doped ZnO, and this tendency correlates with the reduction of the optical gap width. As a result of our studies, we have arrived at an important conclusion that thermal treatment of ZnO:nC composites allows a C-doped ZnO with high catalytic activity. This increasing photoactivity of C-doped ZnO aggregates is attributed to the optimal specific surface area and electron-energy spectrum restructuring to be produced owing to the presence of singly charged oxygen vacancies and carbon dissolved in the ZnO lattice.

  13. Chemical growth of ZnO nanorod arrays on textured nanoparticle nanoribbons and its second-harmonic generation performance

    NASA Astrophysics Data System (ADS)

    Gui, Zhou; Wang, Xian; Liu, Jian; Yan, Shanshan; Ding, Yanyan; Wang, Zhengzhou; Hu, Yuan

    2006-07-01

    On the basis of the highly oriented ZnO nanoparticle nanoribbons as the growth seed layer (GSL) and solution growth technique, we have synthesized vertical ZnO nanorod arrays with high density over a large area and multi-teeth brush nanostructure, respectively, according to the density degree of the arrangement of nanoparticle nanoribbons GSL on the glass substrate. This controllable and convenient technique opens the possibility of creating nanostructured film for industrial fabrication and may represent a facile way to get similar structures of other compounds by using highly oriented GSL to promote the vertical arrays growth. The growth mechanism of the formation of the ordered nanorod arrays is also discussed. The second-order nonlinear optical coefficient d31 of the vertical ZnO nanorod arrays measured by the Maker fringes technique is 11.3 times as large as that of d36 KH 2PO 4 (KDP).

  14. Structural, morphological and magnetic properties of pure and Ni-doped ZnO nanoparticles synthesized by sol-gel method

    NASA Astrophysics Data System (ADS)

    Undre, Pallavi G.; Birajdar, Shankar D.; Kathare, R. V.; Jadhav, K. M.

    2018-05-01

    In this work pure and Ni-doped ZnO nanoparticles have been prepared by sol-gel method. Influence of nickel doping on structural, morphological and magnetic properties of prepared nanoparticles was investigated by X-ray diffraction technique (XRD), Scanning electron microscopy (SEM) and Pulse field magnetic hysteresis loop. X-ray diffraction pattern shows the formation of a single phase with hexagonal wurtzite structure of both pure and Ni-doped ZnO nanoparticles. The lattice parameters `an' and `c' of Ni-doped ZnO is slightly less than that of pure ZnO nanoparticles. The crystalline size of prepared nanoparticles is found to be in 29 and 31 nm range. SEM technique used to examine the surface morphology of samples, SEM image confirms the nanocrystalline nature of present samples. From the pulse field hysteresis loop technique pure and Ni-doped ZnO nanoparticles show diamagnetic and ferromagnetic behavior at room temperature respectively.

  15. Nanostructure CdS/ZnO heterojunction configuration for photocatalytic degradation of Methylene blue

    NASA Astrophysics Data System (ADS)

    Velanganni, S.; Pravinraj, S.; Immanuel, P.; Thiruneelakandan, R.

    2018-04-01

    In the present manuscript, thin films of Zinc Oxide (ZnO) have been deposited on a FTO substrate using a simple successive ionic layer adsorption and reaction (SILAR) and chemical bath deposition (CBD) method. Cadmium Sulphide (CdS) nanoparticles are sensitized over ZnO thin films using SILAR method. The synthesized nanostructured CdS/ZnO heterojunction thin films was characterized by X-ray diffraction (XRD), Scanning electron microscopy (SEM), High resolution transmission electron microscopy (HR-TEM), X-ray photoelectron spectroscopy (XPS), UV-Vis spectroscopy and Raman spectroscopy techniques. The band gap of CdS nanoparticles over ZnO nanostructure was found to be about 3.20 eV. The photocatalytic activities of the deposited CdS/ZnO thin films were evaluated by the degradation of methylene blue (MB) in an aqueous solution under sun light irradiation.

  16. Improved Sensitivity with Low Limit of Detection of a Hydrogen Gas Sensor Based on rGO-Loaded Ni-Doped ZnO Nanostructures.

    PubMed

    Bhati, Vijendra Singh; Ranwa, Sapana; Rajamani, Saravanan; Kumari, Kusum; Raliya, Ramesh; Biswas, Pratim; Kumar, Mahesh

    2018-04-04

    We report enhanced hydrogen-gas-sensing performance of a Ni-doped ZnO sensor decorated with the optimum concentration of reduced graphene oxide (rGO). Ni-doped ZnO nanoplates were grown by radio frequency sputtering, rGO was synthesized by Hummer's method and decorated by the drop cast method of various concentration of rGO (0-1.5 wt %). The current-voltage characteristics of the rGO-loaded sensor are highly influenced by the loading concentration of rGO, where current conduction decreases and sensor resistance increases as the rGO concentration is increased up to 0.75 wt % because of the formation of various Schottky heterojunctions at rGO/ZnO interfaces. With the combined effect of more active site availability and formation of various p-n heterojunctions due to the optimum loading concentration of rGO (0.75 wt %), the sensor shows the maximum sensing response of ∼63.8% for 100 ppm hydrogen at moderate operating temperature (150 °C). The rGO-loaded sensors were able to detect a minimum of 1 ppm hydrogen concentration and showed high selectivity. However, a further increase in the rGO concentration (1.5 wt %) leads to the reduction of the relative response of hydrogen gas, ascribed to the formation of interconnections of rGO between electrodes. Therefore, it reduces the total resistance of the sensor and minimizes the effect of p-n heterojunction on sensor response.

  17. Influence of Co doping on combined photocatalytic and antibacterial activity of ZnO nanoparticles

    NASA Astrophysics Data System (ADS)

    Anandan, M.; Dinesh, S.; Krishnakumar, N.; Balamurugan, K.

    2016-11-01

    The present work aims to investigate the structural, optical, photocatalyst and antibacterial properties of bare and cobalt doped ZnO nanoparticles (NPs) with different concentrations Zn1-x Co x O (x = 0, 0.03, 0.06 and 0.09) synthesized by co-precipitation method. The XRD patterns confirmed that all samples of cobalt doped ZnO nanostructures revealed the formation of single phase having hexagonal wurtzite structure with crystallite size in the range of 31-41 nm. Further, the decreasing trend in lattice parameters and grain sizes were also seen with increasing doping concentrations which confirms the incorporation of Co ions into the ZnO lattice. This result was further supported by the FT-IR data. HR-TEM images demonstrated the distinct hexagonal like morphology with small agglomeration. The UV-visible absorption spectra exhibits red shift with increase in Co doping concentration in ZnO while corresponding bandgap energy of cobalt doped ZnO NPs decreased with increased Co doping concentration. PL spectra showed a weak UV and visible emission band which may be ascribed to the reduction in oxygen vacancy and defects by cobalt doping. XPS and EDX spectral results confirm the composition and the purity of Co doped ZnO NPs. Furthermore, the Co doped ZnO NPs were found to exhibit lesser photocatalytic activity for the degradation of methyl green dye under UV light illumination in comparison with the bare ZnO NPs. Moreover, anti-bacterial studies reveals that the Co doped ZnO NPs possess more antibacterial effect against gram positive Basillus subtills and gram negative Klebsiella pneumoniae bacterial strains than the bare ZnO NPs.

  18. Micromechanical Properties of Nanostructured Clay-Oxide Multilayers Synthesized by Layer-by-Layer Self-Assembly.

    PubMed

    Hou, Dongwei; Zhang, Guoping; Pant, Rohit Raj; Wei, Zhongxin; Shen, Shuilong

    2016-11-08

    Clay-based nanostructured multilayers, such as clay-polymer multilayers and clay-oxide multilayers, have attracted growing attention owing to their remarkable mechanical properties and promising application in various fields. In this paper, synthesis of a new kind of nanostructured clay-oxide multilayers by layer-by-layer self-assembly was explored. Nano-mechanical characterization of 18 clay-based multilayer samples, prepared under as-deposited (i.e., air-dried) and annealing conditions at 400 °C/600 °C with different precursor cations and multilayer structure, were carried out using nanoindentation testing, atomic force microscopy (AFM), and X-ray diffraction (XRD). The influencing factors, including as-deposited and annealing conditions and clay concentrations on the mechanical properties were analyzed. Results show that all of the multilayers exhibit high bonding strength between interlayers. Higher modulus and hardness of clay-based multilayers were obtained with lower clay concentrations than that with higher clay concentrations. Different relationships between the modulus and hardness and the annealing temperature exist for a specific type of clay-oxide multilayer. This work offers the basic and essential knowledge on design of clay-based nanostructured multilayers by layer-by-layer self-assembly.

  19. Zno Micro/Nanostructures Grown on Sapphire Substrates Using Low-Temperature Vapor-Trapped Thermal Chemical Vapor Deposition: Structural and Optical Properties.

    PubMed

    Hu, Po-Sheng; Wu, Cheng-En; Chen, Guan-Lin

    2017-12-21

    In this research, the Zn(C₅H₇O₂)₂·xH₂O-based growth of ZnO micro/nanostructures in a low temperature, vapor-trapped chemical vapor deposition system was attempted to optimize structural and optical properties for potential biomedical applications. By trapping in-flow gas molecules and Zinc vapor inside a chamber tube by partially obstructing a chamber outlet, a high pressure condition can be achieved, and this experimental setup has the advantages of ease of synthesis, being a low temperature process, and cost effectiveness. Empirically, the growth process proceeded under a chamber condition of an atmospheric pressure of 730 torr, a controlled volume flow rate of input gas, N₂/O₂, of 500/500 Standard Cubic Centimeters per Minute (SCCM), and a designated oven temperature of 500 °C. Specifically, the dependence of structural and optical properties of the structures on growth duration and spatially dependent temperature were investigated utilizing scanning electron microscopy, X-ray diffraction (XRD), photoluminescence (PL), and ultraviolet-visible transmission spectroscopy. The experimental results indicate that the grown thin film observed with hexagonal structures and higher structural uniformity enables more prominent structural and optical signatures. XRD spectra present the dominant peaks along crystal planes of (002) and (101) as the main direction of crystallization. In addition, while the structures excited with laser wavelength of 325 nm emit a signature radiation around 380 nm, an ultraviolet lamp with a wavelength of 254 nm revealed distinctive photoluminescence peaks at 363.96 nm and 403.52 nm, elucidating different degrees of structural correlation as functions of growth duration and the spatial gradient of temperature. Transmittance spectra of the structures illustrate typical variation in the wavelength range of 200 nm to 400 nm, and its structural correlation is less significant when compared with PL.

  20. Zno Micro/Nanostructures Grown on Sapphire Substrates Using Low-Temperature Vapor-Trapped Thermal Chemical Vapor Deposition: Structural and Optical Properties

    PubMed Central

    Hu, Po-Sheng; Wu, Cheng-En; Chen, Guan-Lin

    2017-01-01

    In this research, the Zn(C5H7O2)2·xH2O-based growth of ZnO micro/nanostructures in a low temperature, vapor-trapped chemical vapor deposition system was attempted to optimize structural and optical properties for potential biomedical applications. By trapping in-flow gas molecules and Zinc vapor inside a chamber tube by partially obstructing a chamber outlet, a high pressure condition can be achieved, and this experimental setup has the advantages of ease of synthesis, being a low temperature process, and cost effectiveness. Empirically, the growth process proceeded under a chamber condition of an atmospheric pressure of 730 torr, a controlled volume flow rate of input gas, N2/O2, of 500/500 Standard Cubic Centimeters per Minute (SCCM), and a designated oven temperature of 500 °C. Specifically, the dependence of structural and optical properties of the structures on growth duration and spatially dependent temperature were investigated utilizing scanning electron microscopy, X-ray diffraction (XRD), photoluminescence (PL), and ultraviolet-visible transmission spectroscopy. The experimental results indicate that the grown thin film observed with hexagonal structures and higher structural uniformity enables more prominent structural and optical signatures. XRD spectra present the dominant peaks along crystal planes of (002) and (101) as the main direction of crystallization. In addition, while the structures excited with laser wavelength of 325 nm emit a signature radiation around 380 nm, an ultraviolet lamp with a wavelength of 254 nm revealed distinctive photoluminescence peaks at 363.96 nm and 403.52 nm, elucidating different degrees of structural correlation as functions of growth duration and the spatial gradient of temperature. Transmittance spectra of the structures illustrate typical variation in the wavelength range of 200 nm to 400 nm, and its structural correlation is less significant when compared with PL. PMID:29267196

  1. Gas-sensing performances of Cd-doped ZnO nanoparticles synthesized by a surfactant-mediated method for n-butanol gas

    NASA Astrophysics Data System (ADS)

    Zhao, Rongjun; Li, Kejin; Wang, Zhezhe; Xing, Xinxin; Wang, Yude

    2018-01-01

    Zinc oxide nanoparticles with the different Cd doping contents were prepared by with a surfactant-mediated method in this paper. The effects of Cd doping on the gas sensing properties of the ZnO nanoparticles were studied. The morphology and microstructure of as-prepared samples were characterized by X-ray diffraction (XRD); scanning electron microscopy (SEM), transmission electron microscopy (TEM), and high-resolution TEM (HRTEM), respectively. The results reveal that all the products are the high crystalline hexagonal wurtzite ZnO crystal structure. The gas-sensing characteristics of the Cd doped ZnO nanoparticles for volatile organic compounds (VOCs) were investigated. At its optimal operation temperature of 300 °C, the sensing properties of the Cd doped ZnO nanoparticles for n-butanol gas exhibit a high-performance gas sensing performances including high gas response, good selectivity, response/recovery time, and repeatability as well as stability. Especially, its response reaches 130 for 100 ppm n-butanol of ZnO nanoparticles with 2.5% Cd doping. Those values demonstrate the potential of using as-prepared Cd doped ZnO nanoparticles for n-butanol gas detection, making them to be promising candidates for practical detectors to n-butanol gas. Apart from these, the mechanism related to the advanced properties was also investigated and presented.

  2. Fe-tannic acid complex dye as photo sensitizer for different morphological ZnO based DSSCs

    NASA Astrophysics Data System (ADS)

    Çakar, Soner; Özacar, Mahmut

    2016-06-01

    In this paper we have synthesized different morphological ZnO nanostructures via microwave hydrothermal methods at low temperature within a short time. We described different morphologies of ZnO at different Zn(NO3)2/KOH mole ratio. The ZnO nanostructures were characterized via X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM) and UV-vis spectrophotometry. All ZnO structures have hexagonal wurtzite type structures. The FESEM images showed various morphologies of ZnO such as plate, rod and nanoparticles. Dye sensitized solar cells have been assembled by these different morphological structures photo electrode and tannic acid or Fe-tannic acid complex dye as sensitizer. We have achieved at maximum efficiencies of photovoltaic cells prepared with ZnO plate in all dye systems. The conversion efficiencies of dye sensitized solar cells are 0.37% and 1.00% with tannic acid and Fe-tannic acid complex dye, respectively.

  3. Oxidized guar gum-ZnO hybrid nanostructures: synthesis, characterization and antibacterial activity

    NASA Astrophysics Data System (ADS)

    Singh, Vandana; Dwivedi, Lalit Mohan; Baranwal, Kirti; Asthana, Sugandha; Sundaram, Shanthy

    2018-04-01

    In the present study, guar gum (GG) and oxidized guar gum (OGG) have been used for modulating the antibacterial activity of ZnO. Oxidized guar gum-zinc oxide (OGG-ZnO) or guar gum-zinc oxide (GG-ZnO) nanostructures were synthesized by adding aqueous ammonia to zinc acetate solution in the presence of OGG or GG, respectively. OGG could significantly enhance the antibacterial activity of ZnO for a range of Gram-negative and Gram-positive bacterial strains and this enhancement was most pronounced for Bacillus subtilis and Salmonella typhi. At the same time, GG-ZnO nanostructures were found to be less bioactive than the pure ZnO for the same strains. TEM analysis revealed that optimum OGG-ZnO nanostructure (Z4) is of 200 nm size, oblong in shape, and has slightly clustered texture, while XRD confirmed its crystalline structure with hexagonal phase. The extra surface oxygen species (thus oxygen deficiency) has been assigned for better antibacterial behavior of OGG-ZnO. The study may be extended for other polysaccharide/derivatives to obtain ZnO nanostructures with enhanced antibacterial properties.

  4. Self-assembled photosystem-I biophotovoltaics on nanostructured TiO(2 )and ZnO.

    PubMed

    Mershin, Andreas; Matsumoto, Kazuya; Kaiser, Liselotte; Yu, Daoyong; Vaughn, Michael; Nazeeruddin, Md K; Bruce, Barry D; Graetzel, Michael; Zhang, Shuguang

    2012-01-01

    The abundant pigment-protein membrane complex photosystem-I (PS-I) is at the heart of the Earth's energy cycle. It is the central molecule in the "Z-scheme" of photosynthesis, converting sunlight into the chemical energy of life. Commandeering this intricately organized photosynthetic nanocircuitry and re-wiring it to produce electricity carries the promise of inexpensive and environmentally friendly solar power. We here report that dry PS-I stabilized by surfactant peptides functioned as both the light-harvester and charge separator in solar cells self-assembled on nanostructured semiconductors. Contrary to previous attempts at biophotovoltaics requiring elaborate surface chemistries, thin film deposition, and illumination concentrated into narrow wavelength ranges the devices described here are straightforward and inexpensive to fabricate and perform well under standard sunlight yielding open circuit photovoltage of 0.5 V, fill factor of 71%, electrical power density of 81 µW/cm(2) and photocurrent density of 362 µA/cm(2), over four orders of magnitude higher than any photosystem-based biophotovoltaic to date.

  5. Self-assembled photosystem-I biophotovoltaics on nanostructured TiO2 and ZnO

    PubMed Central

    Mershin, Andreas; Matsumoto, Kazuya; Kaiser, Liselotte; Yu, Daoyong; Vaughn, Michael; Nazeeruddin, Md. K.; Bruce, Barry D.; Graetzel, Michael; Zhang, Shuguang

    2012-01-01

    The abundant pigment-protein membrane complex photosystem-I (PS-I) is at the heart of the Earth’s energy cycle. It is the central molecule in the “Z-scheme” of photosynthesis, converting sunlight into the chemical energy of life. Commandeering this intricately organized photosynthetic nanocircuitry and re-wiring it to produce electricity carries the promise of inexpensive and environmentally friendly solar power. We here report that dry PS-I stabilized by surfactant peptides functioned as both the light-harvester and charge separator in solar cells self-assembled on nanostructured semiconductors. Contrary to previous attempts at biophotovoltaics requiring elaborate surface chemistries, thin film deposition, and illumination concentrated into narrow wavelength ranges the devices described here are straightforward and inexpensive to fabricate and perform well under standard sunlight yielding open circuit photovoltage of 0.5 V, fill factor of 71%, electrical power density of 81 µW/cm2 and photocurrent density of 362 µA/cm2, over four orders of magnitude higher than any photosystem-based biophotovoltaic to date. PMID:22355747

  6. Effect of thermal annealing on the structure and magnetism of Fe-doped ZnO nanocrystals synthesized by solid state reaction

    NASA Astrophysics Data System (ADS)

    Wang, Dong; Chen, Z. Q.; Wang, D. D.; Gong, J.; Cao, C. Y.; Tang, Z.; Huang, L. R.

    2010-11-01

    High purity Fe 2O 3/ZnO nanocomposites were annealed in air at different temperatures between 100 and 1200 °C to get Fe-doped ZnO nanocrystals. The structure and grain size of the Fe 2O 3/ZnO nanocomposites were investigated by X-ray diffraction 2θ scans. Annealing induces an increase of the grain size from 25 to 195 nm and appearance of franklinite phase of ZnFe 2O 4. Positron annihilation measurements reveal large number of vacancy defects in the interface region of the Fe 2O 3/ZnO nanocomposites, and they are gradually recovered with increasing annealing temperature. After annealing at temperatures higher than 1000 °C, the number of vacancies decreases to the lower detection limit of positrons. Room temperature ferromagnetism can be observed in Fe-doped ZnO nanocrystals using physical properties measurement system. The ferromagnetism remains after annealing up to 1000 °C, suggesting that it is not related with the interfacial defects.

  7. Field emission properties of nano-structured cobalt ferrite (CoFe2O4) synthesized by low-temperature chemical method

    NASA Astrophysics Data System (ADS)

    Ansari, S. M.; Suryawanshi, S. R.; More, M. A.; Sen, Debasis; Kolekar, Y. D.; Ramana, C. V.

    2018-06-01

    We report on the field-emission properties of structure-morphology controlled nano-CoFe2O4 (CFO) synthesized via a simple and low-temperature chemical method. Structural analyses indicate that the spongy-CFO (approximately, 2.96 nm) is nano-structured, spherical, uniformly-distributed, cubic-structured and porous. Field emission studies reveal that CFO exhibit low turn-on field (4.27 V/μm) and high emission current-density (775 μA/cm2) at a lower applied electric field of 6.80 V/μm. In addition, extremely good emission current stability is obtained at a pre-set value of 1 μA and high emission spot-density over large area (2 × 2 cm2) suggesting the applicability of these materials for practical applications in vacuum micro-/nano-electronics.

  8. Investigation of microstructural and optical properties of La0.8Ca0.2FeO3 nanostructure synthesized via gel combustion method

    NASA Astrophysics Data System (ADS)

    Naseem, Swaleha; Ali, S. Asad; Khan, Wasi; Khan, Shakeel

    2018-05-01

    Ca substituted LaFeO3 orthoferrite nanostructure perovskite has been synthesized by gel combustion method using citric acid as a fuel. The structural and optical properties were investigated by various tools. The structural analysis through Rietveld refinement of the XRD data revealed single phase of orthorhombic structure in R-3c space group of the sample without presence of any other impurity phase. Scanning electron microscopy (SEM) image exhibits non-uniform distribution of the nanoparticles in agglomerated form. The purity of the sample and stoichiometric ratio of the elements were established through energy dispersive x-ray spectroscopy (EDS). FTIR spectroscopy measurement predicts the presence of various band relation of the chemical species of Ca with LaFeO3. Optical properties were explored through UV-visible absorption spectroscopy that showed absorption edge at 347 nm and energy band gap was estimated as 3.47eV using Tauc's relation.

  9. Antibacterial effect of novel synthesized sulfated β-cyclodextrin crosslinked cotton fabric and its improved antibacterial activities with ZnO, TiO2 and Ag nanoparticles coating.

    PubMed

    Selvam, S; Rajiv Gandhi, R; Suresh, J; Gowri, S; Ravikumar, S; Sundrarajan, M

    2012-09-15

    Sulfated β-cyclodextrin was synthesized from sulfonation of β-cyclodextrin and sulfated polymer was crosslinked with cotton fabric using ethylenediaminetetraacetic acid as crosslinker. ZnO, TiO(2) and Ag nanoparticles were prepared and characterized by XRD, UV, DLS, SEM and PSA. The prepared nanoparticles were coated on crosslinked cotton fabric. The crosslinking and nanoparticles coating effects of cotton fabrics were studied by FTIR and SEM analysis. The antibacterial test was done against gram positive Staphylococcus aureus and gram negative Escherichia coli bacterium. Copyright © 2012 Elsevier B.V. All rights reserved.

  10. Optimization of headspace solid phase microextraction based on nano-structured ZnO combined with gas chromatography-mass spectrometry for preconcentration and determination of ultra-traces of chlorobenzenes in environmental samples.

    PubMed

    Ghasemi, Ensieh; Sillanpää, Mika

    2014-12-01

    In this study, a simple, novel and efficient preconcentration method for the determination of some chlorobenzenes (monochlorobenzene (MCB), three isomeric forms of dichlorobenzene (diCB), 1,3,5-trichlorobenzene (triCB) and hexachlorobenze (hexaCB)) has been developed using a headspace solid phase microextraction (HS-SPME) based on nano-structured ZnO combined with capillary gas chromatography-mass spectrometry (GC-MS). ZnO nanorods have been grown on fused silica fibers using a hydrothermal process. The diameter of ZnO nanorods was in the range of 50-80 nm. The effect of different variables on the extraction efficiency was studied simultaneously using an experimental design. The variables of interest in the HS-SPME were stirring rate, desorption time and temperature, ionic strength, extraction time and temperature. For this purpose, a multivariate strategy was applied based on an experimental design using a Plackett-Burman design for screening and a Box-Behnken design for optimizing of the significant factors. The detection limit and relative standard deviation (RSD) (n=5) for the target analytes were in the range of 0.01-0.1 ng L(-1) and 4.3-7.6%, respectively. The developed technique was found to be successfully applicable to preconcentration and determination of the target analytes in environmental water and soil samples. Copyright © 2014 Elsevier B.V. All rights reserved.

  11. Enhancement of Si solar cell efficiency using ZnO nanowires with various diameters

    NASA Astrophysics Data System (ADS)

    Gholizadeh, A.; Reyhani, A.; Parvin, P.; Mortazavi, S. Z.; Mehrabi, M.

    2018-01-01

    Here, Zinc Oxide nanowires are synthesized using thermal chemical vapor deposition of a Zn granulate source and used to enhance a significant Si-solar cell efficiency with simple and low cost method. The nanowires are grown in various O2 flow rates. Those affect the shape, yield, structure and the quality of ZnO nanowires according to scanning electron microscopy and x-ray diffraction analyses. This delineates that the ZnO nanostructure is dependent on the synthesis conditions. The photoluminescence spectroscopy of ZnO indicates optical emission at the Ultra-Violet and blue-green regions whose intensity varies as a function of diameter of ZnO nano-wires. The optical property of ZnO layer is measured by UV-visible and diffuse reflection spectroscopy that demonstrate high absorbance at 280-550 nm. Furthermore, the photovoltaic characterization of ZnO nanowires is investigated based on the drop casting on Si-solar cell. The ZnO nanowires with various diameters demonstrate different effects on the efficiency of Si-solar cells. We have shown that the reduction of the spectral reflectance and down-shifting process as well as the reduction of photon trapping are essential parameters on the efficiency of Si-solar cells. However, the latter is dominated here. In fact, the trapped photons during the electron-hole generation are dominant due to lessening the absorption rate in ZnO nano-wires. The results indicate that the mean diameters reduction of ZnO nanowires is also essential to improve the fill factor. The external and internal quantum efficiency analyses attest the efficiency improvement over the blue region which is related to the key parameters above.

  12. Tri-functional Fe2O3-encased Ag-doped ZnO nanoframework: magnetically retrievable antimicrobial photocatalyst

    NASA Astrophysics Data System (ADS)

    Karunakaran, Chockalingam; Vinayagamoorthy, Pazhamalai

    2016-11-01

    Fe2O3-encased ZnO nanoframework was obtained by hydrothermal method and was doped with Ag through photoreduction process. Energy dispersive x-ray spectroscopy, transmission electron microscopy (TEM), high resolution TEM, selected area electron diffractometry, x-ray diffractometry and Raman spectroscopy were employed for the structural characterization of the synthesized material. While the charge transfer resistance of the prepared nanomaterial is larger than those of Fe2O3 and ZnO the coercivity of the nanocomposite is less than that of hydrothermally obtained Fe2O3 nanostructures. Although Fe2O3/Ag-ZnO exhibits weak visible light absorption its band gap energy does not differ from that of ZnO. The photoluminescence of the fabricated nanoframework is similar to that of ZnO. The radiative recombination of charge carriers is slightly slower in Fe2O3/Ag-ZnO than in ZnO. The synthesized Fe2O3-encased Ag-doped ZnO, under UV A light, exhibits sustainable photocatalytic activity to degrade dye and is magnetically recoverable. Also, the Fe2O3/Ag-ZnO nanocomposite disinfects bacteria effectively in absence of direct illumination.

  13. Preferential cytotoxicity of ZnO nanoparticle towards cervical cancer cells induced by ROS-mediated apoptosis and cell cycle arrest for cancer therapy

    NASA Astrophysics Data System (ADS)

    Sirelkhatim, Amna; Mahmud, Shahrom; Seeni, Azman; Kaus, Noor Haida Mohd

    2016-08-01

    The present study aimed to synthesize multifunctional ZnO-NP samples, namely ZnO-20, ZnO-40, and ZnO-80 nm, using different approaches, to be used as efficient anticancer agents. Systematic characterizations revealed their particle sizes and demonstrated nanostructures of nanorods (ZnO-80 nm) and nanogranules (ZnO-20 and ZnO-40 nm). They exhibited significant ( p < 0.05) toxicity to HeLa cancer cells. HeLa cell viabilities at 1 mM dose reduced to 37, 32, 15 %, by ZnO-80, ZnO-40, and ZnO-20 nm, respectively, at 48 h. However, the same dose exerted different effects of 79.6, 76, and 75 % on L929 normal cells at 48 h. Measurement of reactive oxygen species (ROS) showed a considerable ROS yields on HeLa cells by all samples with a pronounced percentage (50 %) displayed by ZnO-20 nm. Moreover, ROS-mediated apoptosis induction and blocked cell cycle progression in the S, G2/M, and G0/G1 phases significantly ( p < 0.05). Apoptosis induction was further confirmed by DNA fragmentation and Hoechst-PI costained images viewed under fluorescence microscope. Additionally, morphological changes of HeLa cells visualized under light microscope showed assortment of cell death involved shrinkage, vacuolization and apoptotic bodies' formation. Most importantly, results exposed the impact of size and morphology of ZnO samples on their toxicity to Hela cells mediated mainly by ROS production. ZnO-20 nm in disk form with its nanogranule shape and smallest particle size was the most toxic sample, followed by ZnO-40 nm and then ZnO-80 nm. An additional proposed mechanism contributed in the cell death herein was ZnO decomposition producing zinc ions (Zn2+) into the acidic cancer microenvironment due to the smaller sizes of ZnO-NPs. This mechanism has been adopted in the literatures as a size-dependent phenomenon. The emerged findings were suggested to provide new platforms in the development of therapeutics as selective agents to the fatal cervical cancer, and to benefit from the

  14. Investigation of structural, optical, catalytic, fluorescence studies of eco-friendly synthesized Bi2S3 nanostructures

    NASA Astrophysics Data System (ADS)

    Ayodhya, Dasari; Veerabhadram, Guttena

    2017-02-01

    A simple solution phase method has been developed for the synthesis of ribonucleosides capped Bi2S3 nanostructures (NSs) with an average diameter of 15 nm and length of below 100 nm. Transmission electron microscopy (TEM), selected-area electron diffraction (SAED), and X-ray diffraction (XRD) studies revealed that these NSs were grown from a colloidal dispersion of amorphous Bi2S3 particles, which was first formed through a thermal reaction at a temperature of 60 °C. The phase and structure of the Bi2S3 NSs have been identified by using X-ray powder diffraction. The crystal structure had orthorhombic structure. The surface properties and morphology have been investigated using scanning electron microscope (SEM) technique. The N2 sorption-desorption experiments showed that the surface area of the NSs was 6.35 m2 g-1 by Brunauer-Emmett-Teller (BET). The experiments showed that the Bi2S3 NSs prepared in the present work could be used as catalyst for the reduction of SO dye using a reducing agent. It was found that the as-obtained Bi2S3 NSs contributed to the best catalytic activity. Photoluminescence experiments showed a quenching of the Bi2S3 fluorescence with increasing L-cysteine (Cys) content in the solution. Furthermore, the proposed NSs as sensor were employed for the determination of metal ions with satisfactory results.

  15. An optimal thermal evaporation synthesis of c-axis oriented ZnO nanowires with excellent UV sensing and emission characteristics

    SciTech Connect

    Saha, Tridib, E-mail: tridib.saha@monash.edu; Achath Mohanan, Ajay, E-mail: ajay.mohanan@monash.edu; Swamy, Varghese, E-mail: varghese.swamy@monash.edu

    Highlights: • c-Axis alignment of ZnO nanowires was optimized using self-seeding thermal evaporation method. • Influence of purified air on the morphology and optoelectronic properties were studied. • Nanowires grown under optimal conditions exhibit strong UV emission peak in PL spectrum. • Optimized growth condition establish nanowires of excellent UV sensing characteristics - Abstract: Well-aligned (c-axis oriented) ZnO nanowire arrays were successfully synthesized on Si (1 0 0) substrates through an optimized self-seeding thermal evaporation method. An open-ended chemical vapor deposition (CVD) setup was used in the experiment, with argon and purified air as reaction gases. Epitaxial growth of c-axismore » oriented ZnO nanowires was observed for 5 sccm flow rate of purified air, whereas Zn/Zn suboxide layers and multiple polycrystalline layers of ZnO were obtained for absence and excess of purified air, respectively. Ultraviolet (UV) sensing and emission properties of the as-grown ZnO nanostructures were investigated through the current–voltage (I–V) characteristics of the nanowires under UV (λ = 365 nm) illumination of 8 mW/cm{sup 2} and using photoluminescence spectra. Nanowires grown under optimum flow of air emitted four times higher intensity of 380 nm UV light as well as exhibited 34 times higher UV radiation sensitivity compared to that of other nanostructures synthesized in this study.« less

  16. The Photocatalytic Application of Semiconductor Stibnite Nanostructure Synthesized via a Simple Microwave-Assisted Approach in Propylene Glycol for Degradation of Dye Pollutants and its Optical Property

    NASA Astrophysics Data System (ADS)

    Saksornchai, Eksuree; Kavinchan, Jutarat; Thongtem, Somchai; Thongtem, Titipun

    2017-11-01

    Stibnite (Sb2S3) semiconducting material was successfully synthesized by a rapid and facile microwave route using antimony chloride (SbCl3) and sodiumthiosulfate (Na2S2O3) dissolved in propylene glycol (PG) containing different hydroxyethyl cellulose (HEC) masses. The phase identification, morphology, and elemental composition of products were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), field- emission scanning electron microscopy (FE-SEM), energy dispersive X-ray (EDX) spectroscopy, and Fourier transform infrared spectroscopy (FTIR). The results revealed the orthorhombic phase of Sb2S3 single crystal-forming sheaf-like nanostructure, and a possible formation mechanism was proposed and discussed. Its direct band gap calculated from UV-visible absorption is 1.60 eV. In this research, the photocatalytic activities of Sb2S3 nanostructure were investigated through the degradation of methyl orange (MO) and methylene blue (MB) under visible light irradiation. The as-obtained 0.30 g HEC-added solution (0.3 HEC-Sb2S3) photocatalyst exhibited better photocatalytic activity than the other products, which degraded 91% of MO within 300 min and 90% of MB within 240 min under the Xe-lamp irradiation. The first-order plot was fitted with this experiment which the rate constant ( k) of 0.3 HEC-Sb2S3 for MO and MB degradation are 0.0085 and 0.0098 min-1, respectively. Therefore, the new experience with a novel and simple synthetic procedure of Sb2S3 photocatalyst that exhibits the characteristics of a highly effective photocatalyst under visible light irradiation was discovered.

  17. Sol–gel synthesized zinc oxide nanorods and their structural and optical investigation for optoelectronic application

    PubMed Central

    2014-01-01

    Nanostructured zinc oxide (ZnO) nanorods (NRs) with hexagonal wurtzite structures were synthesized using an easy and low-cost bottom-up hydrothermal growth technique. ZnO thin films were prepared with the use of four different solvents, namely, methanol, ethanol, isopropanol, and 2-methoxyethanol, and then used as seed layer templates for the subsequent growth of the ZnO NRs. The influences of the different solvents on the structural and optical properties were investigated through scanning electron microscopy, X-ray diffraction, Fourier transform infrared spectroscopy, ultraviolet–visible spectroscopy, and photoluminescence. The obtained X-ray diffraction patterns showed that the synthesized ZnO NRs were single crystals and exhibited a preferred orientation along the (002) plane. In addition, the calculated results from the specific models of the refractive index are consistent with the experimental data. The ZnO NRs that grew from the 2-methoxyethanol seeded layer exhibited the smallest grain size (39.18 nm), largest diffracted intensities on the (002) plane, and highest bandgap (3.21 eV). PMID:25221458

  18. Enhanced glucose biosensor properties of gold nanoparticle-decorated ZnO nanorods

    NASA Astrophysics Data System (ADS)

    Wang, Zi-Hao; Yang, Chih-Chiang; Su, Yan-Kuin; Ruand, Jian-Long

    2017-04-01

    As new materials have been reported and more knowledge on detailed mechanism of glucose oxidation has been unveiled, the non-enzymatic glucose sensor keeps coming closer to practical applications. Nanostructures with higher surface specific area has great potential applications in sensing devices ZnO nanoords were synthesized in a hydrothermal method using simply available laboratory chemicals. Results showed that as-synthesized Gold Nanoparticle-decorated ZnO Nanorods possessing higher specific surface area, significantly increased the non-enzyme efficiency which in turn improved the sensing performances. The electrode also demonstrated excellent performance in sensing glucose concentration with remarkable sensitivity (46.6 μA/mM-cm2) and good repeatability. This work is expected to open a new avenue to fabricate non-enzymatic electrochemical sensors of glucose involving co-mediating.

  19. Comparative study of textured and epitaxial ZnO films

    NASA Astrophysics Data System (ADS)

    Ryu, Y. R.; Zhu, S.; Wrobel, J. M.; Jeong, H. M.; Miceli, P. F.; White, H. W.

    2000-06-01

    ZnO films were synthesized by pulsed laser deposition (PLD) on GaAs and α-Al 2O 3 substrates. The properties of ZnO films on GaAs and α-Al 2O 3 have been investigated to determine the differences between epitaxial and textured ZnO films. ZnO films on GaAs show very strong emission features associated with exciton transitions as do ZnO films on α-Al 2O 3, while the crystalline structural qualities for ZnO films on α-Al 2O 3 are much better than those for ZnO films on GaAs. The properties of ZnO films are studied by comparing highly oriented, textured ZnO films on GaAs with epitaxial ZnO films on α-Al 2O 3 synthesized along the c-axis.

  20. Hydrothermal-electrochemical growth of heterogeneous ZnO: Co films

    NASA Astrophysics Data System (ADS)

    Yilmaz, Ceren; Unal, Ugur

    2017-10-01

    This study demonstrates the preparation of heterogeneous ZnO: Co nanostructures via hydrothermal-electrochemical deposition at 130 °C and -1.1 V (vs Ag/AgCl (satd)) in dimethyl sulfoxide (DMSO)-H2O mixture. Under the stated conditions, ZnO: Co nanostructures grow preferentially along (002) direction. Strength of directional growth progressively increases with the increasing concentration of Co(II) in the deposition bath. Films are composed of hexagonal Wurtzite ZnO, metallic cobalt, and mixed cobalt oxide on the surface and cobalt(II) oxide in deeper levels. Increasing the Co(II) concentration in the deposition bath results in different morphological features as well as phase separation. Platelets, sponge-like structures, cobalt-rich spheres, microislands of cobalt-rich spheres which are interconnected by ZnO network can be synthesized by adjusting [Co(II)]: [Zn(II)] ratio. Growth mechanisms giving rise to these particular structures, surface morphology, crystal structure, phase purity, chemical binding characteristics, and optical properties of the deposits are discussed in detail.

  1. Self-assembled ultra small ZnO nanocrystals for dye-sensitized solar cell application

    SciTech Connect

    Patra, Astam K.; Dutta, Arghya; Bhaumik, Asim, E-mail: msab@iacs.res.in

    2014-07-01

    We demonstrate a facile chemical approach to produce self-assembled ultra-small mesoporous zinc oxide nanocrystals using sodium salicylate (SS) as a template under hydrothermal conditions. These ZnO nanomaterials have been successfully fabricated as a photoanode for the dye-sensitized solar cell (DSSC) in the presence of N719 dye and iodine–triiodide electrolyte. The structural features, crystallinity, purity, mesophase and morphology of the nanostructure ZnO are investigated by several characterization tools. N{sub 2} sorption analysis revealed high surface areas (203 m{sup 2} g{sup −1}) and narrow pore size distributions (5.1–5.4 nm) for different samples. The mesoporous structure and strong photoluminescence facilitates the high dyemore » loading at the mesoscopic void spaces and light harvesting in DSSC. By utilizing this ultra-small ZnO photoelectrode with film thickness of about 7 μm in the DSSC with an open-circuit voltage (V{sub OC}) of 0.74 V, short-circuit current density (J{sub SC}) of 3.83 mA cm{sup −2} and an overall power conversion efficiency of 1.12% has been achieved. - Graphical abstract: Ultra-small ZnO nanocrystals have been synthesized with sodium salicylate as a template and using it as a photoanode in a dye-sensitized solar cell 1.12% power conversion efficiency has been observed. - Highlights: • Synthesis of self-assembled ultra-small mesoporous ZnO nanocrystals by using sodium salicylate as a template. • Mesoporous ZnO materials have high BET surface areas and void space. • ZnO nanoparticles serve as a photoanode for the dye-sensitized solar cell (DSSC). • Using ZnO nanocrystals as photoelectrode power conversion efficiency of 1.12% has been achieved.« less

  2. Growth and characterization of ZnO multipods on functional surfaces with different sizes and shapes of Ag particles

    NASA Astrophysics Data System (ADS)

    A, Kamalianfar; S, A. Halim; Mahmoud Godarz, Naseri; M, Navasery; Fasih, Ud Din; J, A. M. Zahedi; Kasra, Behzad; K, P. Lim; A Lavari, Monghadam; S, K. Chen

    2013-08-01

    Three-dimensional ZnO multipods are successfully synthesized on functional substrates using the vapor transport method in a quartz tube. The functional surfaces, which include two different distributions of Ag nanoparticles and a layer of commercial Ag nanowires, are coated onto silicon substrates before the growth of ZnO nanostructures. The structures and morphologies of the ZnO/Ag heterostructures are investigated using X-ray diffraction and field emission scanning electron microscopy. The sizes and shapes of the Ag particles affect the growth rates and initial nucleations of the ZnO structures, resulting in different numbers and shapes of multipods. They also influence the orientation and growth quality of the rods. The optical properties are studied by photoluminescence, UV-vis, and Raman spectroscopy. The results indicate that the surface plasmon resonance strongly depends on the sizes and shapes of the Ag particles.

  3. High power density cell using nanostructured Sr-doped SmCoO3 and Sm-doped CeO2 composite powder synthesized by spray pyrolysis

    NASA Astrophysics Data System (ADS)

    Shimada, Hiroyuki; Yamaguchi, Toshiaki; Suzuki, Toshio; Sumi, Hirofumi; Hamamoto, Koichi; Fujishiro, Yoshinobu

    2016-01-01

    High power density solid oxide electrochemical cells were developed using nanostructure-controlled composite powder consisting of Sr-doped SmCoO3 (SSC) and Sm-doped CeO2 (SDC) for electrode material. The SSC-SDC nano-composite powder, which was synthesized by spray pyrolysis, had a narrow particle size distribution (D10, D50, and D90 of 0.59, 0.71, and 0.94 μm, respectively), and individual particles were spherical, composing of nano-size SSC and SDC fragments (approximately 10-15 nm). The application of the powder to a cathode for an anode-supported solid oxide fuel cell (SOFC) realized extremely fine cathode microstructure and excellent cell performance. The anode-supported SOFC with the SSC-SDC cathode achieved maximum power density of 3.65, 2.44, 1.43, and 0.76 W cm-2 at 800, 750, 700, and 650 °C, respectively, using humidified H2 as fuel and air as oxidant. This result could be explained by the extended electrochemically active region in the cathode induced by controlling the structure of the starting powder at the nano-order level.

  4. Fabrication and characterization of ZnS/ZnO core shell nanostructures on silver wires

    NASA Astrophysics Data System (ADS)

    Kao, Chyuan Haur; Su, Wei Ming; Li, Cheng Yuan; Weng, Wei Chih; Weng, Chen Yuan; Cheng, Chin-Chi; Lin, Yung-Sen; Lin, Chia Feng; Chen, Hsiang

    2018-06-01

    In this research, ZnS nanoparticles were synthesized on ZnO/silver wires to form ZnS/ZnO core shell structures. Various outward appearance and colors could be observed by different ZnO growth and sulfurization conditions. To evaluate the properties of these nanostructures, optical properties and chemical bindings were analyzed by photoluminescence, Raman analysis, and X-ray photoelectron spectroscopy. Furthermore, material characterizations including transmission electron microscopy and X-ray diffraction confirmed that cubic ZnS (311)/ZnO nanostructures were grown on silver wires for the first time. ZnS/ZnO core shell structures on silver wires are promising for future optoelectronic and biomedical applications.

  5. Improvements in electrical and dielectric properties of substituted multiferroic LaMnO{sub 3} based nanostructures synthesized by co-precipitation method

    SciTech Connect

    Mahmood, Azhar; Warsi, Muhammad Farooq, E-mail: Farooq.warsi@iub.edu.pk; Ashiq, Muhammad Naeem

    2012-12-15

    Graphical abstract: Display Omitted Highlights: ► Simultaneous double ion substitutions philosophy is introduced in LaMnO{sub 3}. ► La{sub 1−x}Gd{sub x}Mn{sub 1−y}Cr{sub y}O{sub 3} nanoparticles are not reported previously. ► La{sub 1−x}Gd{sub x}Mn{sub 1−y}Cr{sub y}O{sub 3} nanoparticles are synthesized by co-precipitation method. ► The 12 fold increase in resistivity of LaMnO{sub 3} nanostructures is observed. -- Abstract: A series of La{sub 1−x}Gd{sub x}Mn{sub 1−y}Cr{sub y}O{sub 3} nanoparticles (where x, y = 0, 0.25, 0.50, 0.75 and 1.0) has been synthesized by the chemical co-precipitation method, involving double ion substitution philosophy. The nanoparticles were characterized by thermo gravimetric analysis (TGA), X-ray fluorescencemore » spectrometry (XRF), X-ray diffraction (XRD), scanning electron microscopy (SEM), Fourier transform infrared (FTIR) spectroscopy, vibrating sample magnetometer (VSM), DC electrical resistivity and dielectric measurements. The XRD and FTIR analysis confirmed the single orthorhombic phase and the crystallite size were found in the range of 16–34 nm. DC resistivity exhibited very interesting behavior which increased from 1.41 × 10{sup 8} to 16.35 ± 0.2 × 10{sup 8} Ω cm upon complete double ions replacement of La and Mn with Gd and Cr, respectively. This very high resistivity variation upon substitution definitely would open new avenues for applications of these materials in microwave devices and other related areas. The dielectric properties of these nanoparticles were also studied at room temperature in the range of 6 kHz to 5 MHz and the maximum dielectric behavior (ε′ = 2.86 × 10{sup 3}, tan δ = 5.41, ε″ = 15.5 × 10{sup 3}) was exhibited by La{sub 0.75}Gd{sub 0.25}Mn{sub 0.75}Cr{sub 0.25}O{sub 3} at 6 kHz. Hysteresis loops measurements showed that the synthesized nanomaterials are paramagnetic in nature at room temperature.« less

  6. Rapid and selective detection of acetone using hierarchical ZnO gas sensor for hazardous odor markers application.

    PubMed

    Jia, Qianqian; Ji, Huiming; Zhang, Ying; Chen, Yalu; Sun, Xiaohong; Jin, Zhengguo

    2014-07-15

    Hierarchical nanostructured ZnO dandelion-like spheres were synthesized via solvothermal reaction at 200°C for 4h. The products were pure hexagonal ZnO with large exposure of (002) polar facet. Side-heating gas sensor based on hierarchical ZnO spheres was prepared to evaluate the acetone gas sensing properties. The detection limit to acetone for the ZnO sensor is 0.25ppm. The response (Ra/Rg) toward 100ppm acetone was 33 operated at 230°C and the response time was as short as 3s. The sensor exhibited remarkable acetone selectivity with negligible response toward other hazardous gases and water vapor. The high proportion of electron depletion region and oxygen vacancies contributed to high gas response sensitivity. The hollow and porous structure of dandelion-like ZnO spheres facilitated the diffusion of gas molecules, leading to a rapid response speed. The largely exposed (002) polar facets could adsorb acetone gas molecules easily and efficiently, resulting in a rapid response speed and good selectivity of hierarchical ZnO spheres gas sensor at low operating temperature. Copyright © 2014 Elsevier B.V. All rights reserved.

  7. Synthesis of nano-sized ZnO particles by co-precipitation method with variation of heating time

    SciTech Connect

    Purwaningsih, S. Y., E-mail: sriyanisaputri@gmail.com; Pratapa, S.; Triwikantoro

    Zinc oxide powders have been synthesized by a co-precipitation method at low temperature (85 °C), using zinc acetate dihydrate, ammonia, hydrochloric acid solutions as the reactants. A number of process parameters such as reaction temperature, solution basicity or pH and heating time are the main factors affecting the morphology and physical properties of the ZnO nanostructures. In this work the effect of heating time on the morphology and particles size were studied. The as-synthesized ZnO powders were characterized using transmission electron microscopy (TEM) and X-ray diffraction (XRD) techniques. The samples were also analyzed using Fourier transform infrared (FTIR). Rietveld refinementmore » of XRD data confirms that ZnO crystallizes in the hexagonal wurtzite structure with high degree of purity and the (101) plane predominant. The XRD results show that the average crystallite sizes were about 66, 27 and 12 nm for 3, 4 and 5 h of heating times, respectively. The XRD analysis indicated that a fraction of nano-sized ZnO powders were in the form of aggregates, which was also verified by TEM image. The TEM photograph demonstrated that the nano-sized ZnO particles were a pseudo-spherical shape.« less

  8. Fabrication of ZnO nanoparticles based sensitive methanol sensor and efficient photocatalyst

    NASA Astrophysics Data System (ADS)

    Faisal, M.; Khan, Sher Bahadar; Rahman, Mohammed M.; Jamal, Aslam; Abdullah, M. M.

    2012-07-01

    ZnO nanoparticles (NPs) were prepared by hydrothermal treatment with starting materials (zinc chloride and urea) in the presence of ammonium hydroxide and characterized by powder X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), Fourier transform infrared spectroscopy (FTIR), Raman spectroscopy and UV-vis spectroscopy. The synthesized nanoparticles are crystalline with wurtzite hexagonal phase having average particle size in the range of 80-130 nm. Photocatalytic activity of the prepared ZnO NPs was evaluated by the degradation of methylene blue and almost complete degradation (91.0%) takes place within 85 min of irradiation time. Prepared ZnO nanostructures possessed high photocatalytic activity when compared with TiO2-UV100. Additionally, the sensing properties of the ZnO films were investigated for various concentrations of methanol in liquid phase by simple I-V technique at room conditions. It was observed that ZnO thin film exhibits good sensitivity (0.9554 μA cm-2 mM-1) towards detection of methanol at room conditions.

  9. Enhanced Ethanol Gas Sensing Properties of SnO2-Core/ZnO-Shell Nanostructures

    PubMed Central

    Tharsika, T.; Haseeb, A. S. M. A.; Akbar, Sheikh A.; Sabri, Mohd Faizul Mohd; Hoong, Wong Yew

    2014-01-01

    An inexpensive single-step carbon-assisted thermal evaporation method for the growth of SnO2-core/ZnO-shell nanostructures is described, and the ethanol sensing properties are presented. The structure and phases of the grown nanostructures are investigated by field-emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM) and X-ray diffraction (XRD) techniques. XRD analysis indicates that the core-shell nanostructures have good crystallinity. At a lower growth duration of 15 min, only SnO2 nanowires with a rectangular cross-section are observed, while the ZnO shell is observed when the growth time is increased to 30 min. Core-shell hierarchical nanostructures are present for a growth time exceeding 60 min. The growth mechanism for SnO2-core/ZnO-shell nanowires and hierarchical nanostructures are also discussed. The sensitivity of the synthesized SnO2-core/ZnO-shell nanostructures towards ethanol sensing is investigated. Results show that the SnO2-core/ZnO-shell nanostructures deposited at 90 min exhibit enhanced sensitivity to ethanol. The sensitivity of SnO2-core/ZnO-shell nanostructures towards 20 ppm ethanol gas at 400 °C is about ∼5-times that of SnO2 nanowires. This improvement in ethanol gas response is attributed to high active sensing sites and the synergistic effect of the encapsulation of SnO2 by ZnO nanostructures. PMID:25116903

  10. Hierarchical Si/ZnO trunk-branch nanostructure for photocurrent enhancement

    PubMed Central

    2014-01-01

    Hierarchical Si/ZnO trunk-branch nanostructures (NSs) have been synthesized by hot wire assisted chemical vapor deposition method for trunk Si nanowires (NWs) on indium tin oxide (ITO) substrate and followed by the vapor transport condensation (VTC) method for zinc oxide (ZnO) nanorods (NRs) which was laterally grown from each Si nanowires (NWs). A spin coating method has been used for zinc oxide (ZnO) seeding. This method is better compared with other group where they used sputtering method for the same process. The sputtering method only results in the growth of ZnO NRs on top of the Si trunk. Our method shows improvement by having the growth evenly distributed on the lateral sides and caps of the Si trunks, resulting in pine-leave-like NSs. Field emission scanning electron microscope image shows the hierarchical nanostructures resembling the shape of the leaves of pine trees. Single crystalline structure for the ZnO branch grown laterally from the crystalline Si trunk has been identified by using a lattice-resolved transmission electron microscope. A preliminary photoelectrochemical (PEC) cell testing has been setup to characterize the photocurrent of sole array of ZnO NR growth by both hydrothermal-grown (HTG) method and VTC method on ITO substrates. VTC-grown ZnO NRs showed greater photocurrent effect due to its better structural properties. The measured photocurrent was also compared with the array of hierarchical Si/ZnO trunk-branch NSs. The cell with the array of Si/ZnO trunk-branch NSs revealed four-fold magnitude enhancement in photocurrent density compared with the sole array of ZnO NRs obtain from VTC processes. PMID:25246872

  11. Facile green fabrication of nanostructure ZnO plates, bullets, flower, prismatic tip, closed pine cone: Their antibacterial, antioxidant, photoluminescent and photocatalytic properties.

    PubMed

    Madan, H R; Sharma, S C; Udayabhanu; Suresh, D; Vidya, Y S; Nagabhushana, H; Rajanaik, H; Anantharaju, K S; Prashantha, S C; Sadananda Maiya, P

    2016-01-05

    Green synthesis of multifunctional Zinc oxide nanoparticles (NPs) with a variety of morphologies were achieved by low temperature solution combustion route employing neem (Azadirachta indica) extract as fuel. The nanoparticles were characterized by PXRD, FTIR, XPS, Raman and UV-Visible spectroscopic studies. The Morphologies were studied by SEM and TEM analysis. The NPs were subjected for photoluminescence, photocatalytic, antibacterial and antioxidant activity studies. PXRD pattern confirmed the hexagonal wurtzite structure of the product. SEM images indicated the transformation of mushroom like hexagonal disks to bullets, buds, cones, bundles and closed pine cone structured NPs with increase in the concentration of neem extract in reaction mixture. The NPs exhibited prominent green emission due to the presence of intrinsic defect centers. The as-formed bullet shaped ZnO with 4ml of neem extract was found to decolorize Methylene blue (MB) under Sunlight and UV light irradiation. The antibacterial studies indicated that ZnO NPs of concentration 500, 750 and 1000μg resulted in significant antibacterial activity on Klebsiella aerogenes and Staphylococcus aureus but not against Escherichia coli and Pseudomonas aeruginosa in agar well diffusion method. Further, ZnO NPs exhibited significant antioxidant activity against scavenging DPPH free radicals. The current investigation demonstrated green engineering method for the synthesis of multifunctional ZnO NPs with interesting morphologies using neem extract. Copyright © 2015 Elsevier B.V. All rights reserved.

  12. Observation of the origin of d0 magnetism in ZnO nanostructures using X-ray-based microscopic and spectroscopic techniques

    NASA Astrophysics Data System (ADS)

    Singh, Shashi B.; Wang, Yu-Fu; Shao, Yu-Cheng; Lai, Hsuan-Yu; Hsieh, Shang-Hsien; Limaye, Mukta V.; Chuang, Chen-Hao; Hsueh, Hung-Chung; Wang, Hsaiotsu; Chiou, Jau-Wern; Tsai, Hung-Ming; Pao, Chih-Wen; Chen, Chia-Hao; Lin, Hong-Ji; Lee, Jyh-Fu; Wu, Chun-Te; Wu, Jih-Jen; Pong, Way-Faung; Ohigashi, Takuji; Kosugi, Nobuhiro; Wang, Jian; Zhou, Jigang; Regier, Tom; Sham, Tsun-Kong

    2014-07-01

    Efforts have been made to elucidate the origin of d0 magnetism in ZnO nanocactuses (NCs) and nanowires (NWs) using X-ray-based microscopic and spectroscopic techniques. The photoluminescence and O K-edge and Zn L3,2-edge X-ray-excited optical luminescence spectra showed that ZnO NCs contain more defects than NWs do and that in ZnO NCs, more defects are present at the O sites than at the Zn sites. Specifically, the results of O K-edge scanning transmission X-ray microscopy (STXM) and the corresponding X-ray-absorption near-edge structure (XANES) spectroscopy demonstrated that the impurity (non-stoichiometric) region in ZnO NCs contains a greater defect population than the thick region. The intensity of O K-edge STXM-XANES in the impurity region is more predominant in ZnO NCs than in NWs. The increase in the unoccupied (occupied) density of states at/above (at/below) the conduction-band minimum (valence-band maximum) or the Fermi level is related to the population of defects at the O sites, as revealed by comparing the ZnO NCs to the NWs. The results of O K-edge and Zn L3,2-edge X-ray magnetic circular dichroism demonstrated that the origin of magnetization is attributable to the O 2p orbitals rather than the Zn d orbitals. Further, the local density approximation (LDA) + U verified that vacancies in the form of dangling or unpaired 2p states (due to Zn vacancies) induced a significant local spin moment in the nearest-neighboring O atoms to the defect center, which was determined from the uneven local spin density by analyzing the partial density of states of O 2p in ZnO.Efforts have been made to elucidate the origin of d0 magnetism in ZnO nanocactuses (NCs) and nanowires (NWs) using X-ray-based microscopic and spectroscopic techniques. The photoluminescence and O K-edge and Zn L3,2-edge X-ray-excited optical luminescence spectra showed that ZnO NCs contain more defects than NWs do and that in ZnO NCs, more defects are present at the O sites than at the Zn sites

  13. Application of Silver Nanostructures Synthesized by Cold Atmospheric Pressure Plasma for Inactivation of Bacterial Phytopathogens from the Genera Dickeya and Pectobacterium.

    PubMed

    Dzimitrowicz, Anna; Motyka, Agata; Jamroz, Piotr; Lojkowska, Ewa; Babinska, Weronika; Terefinko, Dominik; Pohl, Pawel; Sledz, Wojciech

    2018-02-25

    Pectinolytic bacteria are responsible for significant economic losses by causing diseases on numerous plants. New methods are required to control and limit their spread. One possibility is the application of silver nanoparticles (AgNPs) that exhibit well-established antibacterial properties. Here, we synthesized AgNPs, stabilized by pectins (PEC) or sodium dodecyl sulphate (SDS), using a direct current atmospheric pressure glow discharge (dc-APGD) generated in an open-to-air and continuous-flow reaction-discharge system. Characterization of the PEC-AgNPs and SDS-AgNPs with UV/Vis absorption spectroscopy, transmission electron microscopy, energy dispersive X-ray spectroscopy, and selected area electron diffraction revealed the production of spherical, well dispersed, and face cubic centered crystalline AgNPs, with average sizes of 9.33 ± 3.37 nm and 28.3 ± 11.7 nm, respectively. Attenuated total reflection-Fourier transformation infrared spectroscopy supported the functionalization of the nanostructures by PEC and SDS. Antibacterial activity of the AgNPs was tested against Dickeya spp. and Pectobacterium spp. strains. Both PEC-AgNPs and SDS-AgNPs displayed bactericidal activity against all of the tested isolates, with minimum inhibitory concentrations of 5.5 mg∙L -1 and 0.75-3 mg∙L -1 , respectively. The collected results suggest that the dc-APGD reaction-discharge system can be applied for the production of defined AgNPs with strong antibacterial properties, which may be further applied in plant disease management.

  14. Application of Silver Nanostructures Synthesized by Cold Atmospheric Pressure Plasma for Inactivation of Bacterial Phytopathogens from the Genera Dickeya and Pectobacterium

    PubMed Central

    Motyka, Agata; Lojkowska, Ewa; Babinska, Weronika; Terefinko, Dominik; Sledz, Wojciech

    2018-01-01

    Pectinolytic bacteria are responsible for significant economic losses by causing diseases on numerous plants. New methods are required to control and limit their spread. One possibility is the application of silver nanoparticles (AgNPs) that exhibit well-established antibacterial properties. Here, we synthesized AgNPs, stabilized by pectins (PEC) or sodium dodecyl sulphate (SDS), using a direct current atmospheric pressure glow discharge (dc-APGD) generated in an open-to-air and continuous-flow reaction-discharge system. Characterization of the PEC-AgNPs and SDS-AgNPs with UV/Vis absorption spectroscopy, transmission electron microscopy, energy dispersive X-ray spectroscopy, and selected area electron diffraction revealed the production of spherical, well dispersed, and face cubic centered crystalline AgNPs, with average sizes of 9.33 ± 3.37 nm and 28.3 ± 11.7 nm, respectively. Attenuated total reflection-Fourier transformation infrared spectroscopy supported the functionalization of the nanostructures by PEC and SDS. Antibacterial activity of the AgNPs was tested against Dickeya spp. and Pectobacterium spp. strains. Both PEC-AgNPs and SDS-AgNPs displayed bactericidal activity against all of the tested isolates, with minimum inhibitory concentrations of 5.5 mg∙L−1 and 0.75–3 mg∙L−1, respectively. The collected results suggest that the dc-APGD reaction-discharge system can be applied for the production of defined AgNPs with strong antibacterial properties, which may be further applied in plant disease management. PMID:29495328

  15. Highly sensitive hydrogen detection of catalyst-free ZnO nanorod networks suspended by lithography-assisted growth.

    PubMed

    Huh, Junghwan; Park, Jonghyurk; Kim, Gyu Tae; Park, Jeong Young

    2011-02-25

    We have successfully demonstrated a ZnO nanorod-based 3D nanostructure to show a high sensitivity and very fast response/recovery to hydrogen gas. ZnO nanorods have been synthesized selectively over the pre-defined area at relatively low temperature using a simple self-catalytic solution process assisted by a lithographic method. The conductance of the ZnO nanorod device varies significantly as the concentration of the hydrogen is changed without any additive metal catalyst, revealing a high sensitivity to hydrogen gas. Its superior performance can be explained by the porous structure of its three-dimensional network and the enhanced surface reaction of the hydrogen molecules with the oxygen defects resulting from a high surface-to-volume ratio. It was found that the change of conductance follows a power law depending on the hydrogen concentration. A Langmuir isotherm following an ideal power law and a cross-over behavior of the activation energy with respect to hydrogen concentration were observed. This is a very novel and intriguing phenomenon on nanostructured materials, which suggests competitive surface reactions in ZnO nanorod gas sensors.

  16. Enhanced Dibutyl Phthalate Sensing Performance of a Quartz Crystal Microbalance Coated with Au-Decorated ZnO Porous Microspheres

    PubMed Central

    Zhang, Kaihuan; Fan, Guokang; Hu, Ruifen; Li, Guang

    2015-01-01

    Noble metals addition on nanostructured metal oxides is an attractive way to enhance gas sensing properties. Herein, hierarchical zinc oxide (ZnO) porous microspheres decorated with cubic gold particles (Au particles) were synthesized using a facile hydrothermal method. The as-prepared Au-decorated ZnO was then utilized as the sensing film of a gas sensor based on a quartz crystal microbalance (QCM). This fabricated sensor was applied to detect dibutyl phthalate (DBP), which is a widely used plasticizer, and its coating load was optimized. When tested at room temperature, the sensor exhibited a high sensitivity of 38.10 Hz/ppb to DBP in a low concentration range from 2 ppb to 30 ppb and the calculated theoretical detection limit is below 1 ppb. It maintains good repeatability as well as long-term stability. Compared with the undecorated ZnO based QCM, the Au-decorated one achieved a 1.62-time enhancement in sensitivity to DBP, and the selectivity was also improved. According to the experimental results, Au-functionalized ZnO porous microspheres displayed superior sensing performance towards DBP, indicating its potential use in monitoring plasticizers in the gaseous state. Moreover, Au decoration of porous metal oxide nanostructures is proved to be an effective approach for enhancing the gas sensing properties and the corresponding mechanism was investigated. PMID:26343661

  17. A highly sensitive chemical gas detecting device based on N-doped ZnO as a modified nanostructure media: A DFT+NBO analysis

    NASA Astrophysics Data System (ADS)

    Abbasi, Amirali; Sardroodi, Jaber Jahanbin

    2018-02-01

    We presented a density functional theory study of the adsorption of O3 and NO2 molecules on ZnO nanoparticles. Various adsorption geometries of O3 and NO2 over the nanoparticles were considered. For both O3 and NO2 adsorption systems, it was found that the adsorption on the N-doped nanoparticle is more favorable in energy than that on the pristine one. Therefore, the N-doped ZnO has a better efficiency to be utilized as O3 and NO2 detection device. For all cases, the binding sites were located on the zinc atoms of the nanoparticle. The charge analysis based on natural bond orbital (NBO) analysis indicates that charge was transferred from the surface to the adsorbed molecule. The projected density of states of the interacting atoms represent the formation of chemical bonds at the interface region. Molecular orbitals of the adsorption systems indicate that the HOMOs were mainly localized on the adsorbed O3 and NO2 molecules, whereas the electronic densities in the LUMOs were dominant at the ZnO nanocrystal surface. By examining the distribution of spin densities, we found that the magnetization was mainly located over the adsorbed molecules. For NO2 adsorbate, we found that the symmetric and asymmetric stretches were shifted to a lower frequency. The bending stretch mode was shifted to the higher frequency. Our DFT results thus provide a theoretical basis for why the adsorption of O3 and NO2 molecules on the N-doped ZnO nanoparticles may increase, giving rise to design and development of innovative and highly efficient sensor devices for O3 and NO2 recognition.

  18. A Photoactivated Gas Detector for Toluene Sensing at Room Temperature Based on New Coral-Like ZnO Nanostructure Arrays.

    PubMed

    Yeh, Li-Ko; Luo, Jie-Chun; Chen, Min-Chun; Wu, Chih-Hung; Chen, Jian-Zhang; Cheng, I-Chun; Hsu, Cheng-Che; Tian, Wei-Cheng

    2016-10-31

    A photoactivated gas detector operated at room temperature was microfabricated using a simple hydrothermal method. We report that the photoactivated gas detector can detect toluene using a UV illumination of 2 μW/cm². By ultraviolet (UV) illumination, gas detectors sense toluene at room temperature without heating. A significant enhancement of detector sensitivity is achieved because of the high surface-area-to-volume ratio of the morphology of the coral-like ZnO nanorods arrays (NRAs) and the increased number of photo-induced oxygen ions under UV illumination. The corresponding sensitivity (ΔR/R₀) of the detector based on coral-like ZnO NRAs is enhanced by approximately 1022% compared to that of thin-film detectors. The proposed detector greatly extends the dynamic range of detection of metal-oxide-based detectors for gas sensing applications. We report the first-ever detection of toluene with a novel coral-like NRAs gas detector at room temperature. A sensing mechanism model is also proposed to explain the sensing responses of gas detectors based on coral-like ZnO NRAs.

  19. A Photoactivated Gas Detector for Toluene Sensing at Room Temperature Based on New Coral-Like ZnO Nanostructure Arrays

    PubMed Central

    Yeh, Li-Ko; Luo, Jie-Chun; Chen, Min-Chun; Wu, Chih-Hung; Chen, Jian-Zhang; Cheng, I-Chun; Hsu, Cheng-Che; Tian, Wei-Cheng

    2016-01-01

    A photoactivated gas detector operated at room temperature was microfabricated using a simple hydrothermal method. We report that the photoactivated gas detector can detect toluene using a UV illumination of 2 μW/cm2. By ultraviolet (UV) illumination, gas detectors sense toluene at room temperature without heating. A significant enhancement of detector sensitivity is achieved because of the high surface-area-to-volume ratio of the morphology of the coral-like ZnO nanorods arrays (NRAs) and the increased number of photo-induced oxygen ions under UV illumination. The corresponding sensitivity (ΔR/R0) of the detector based on coral-like ZnO NRAs is enhanced by approximately 1022% compared to that of thin-film detectors. The proposed detector greatly extends the dynamic range of detection of metal-oxide-based detectors for gas sensing applications. We report the first-ever detection of toluene with a novel coral-like NRAs gas detector at room temperature. A sensing mechanism model is also proposed to explain the sensing responses of gas detectors based on coral-like ZnO NRAs. PMID:27809222

  20. Low-temperature hydrothermal synthesis of ZnO nanorods: Effects of zinc salt concentration, various solvents and alkaline mineralizers

    SciTech Connect

    Edalati, Khatereh, E-mail: kh_ed834@stu.um.ac.ir; Shakiba, Atefeh; Vahdati-Khaki, Jalil

    2016-02-15

    Highlights: • We synthesized ZnO nanorods by a simple hydrothermal process at 60 °C. • Effects of zinc salt concentration, solvent and alkaline mineralizer was studied. • Increasing concentration of zinc salt changed ZnO nucleation system. • NaOH yielded better results in the production of nanorods in both solvents. • Methanol performed better in the formation of nanorods using the two mineralizers. - Abstract: ZnO has been produced using various methods in the solid, gaseous, and liquid states, and the hydrothermal synthesis at low temperatures has been shown to be an environmentally-friendly one. The current work utilizes a low reactionmore » temperature (60 °C) for the simple hydrothermal synthesis of ZnO nanorod morphologies. Furthermore, the effects of zinc salt concentration, solvent type and alkaline mineralizer type on ZnO nanorods synthesis at a low reaction temperature by hydrothermal processing was studied. Obtained samples were analyzed using X-ray powder diffraction (XRD) and scanning electron microscopy (SEM). Increasing the concentration of the starting zinc salt from 0.02 to 0.2 M changed ZnO nucleation system from the homogeneous to the heterogeneous state. The XRD results confirmed the production hexagonal ZnO nanostructures of with a crystallite size of 40.4 nm. Varying the experimental parameters (mineralizer and solvent) yielded ZnO nanorods with diameters ranging from 90–250 nm and lengths of 1–2 μm.« less

  1. Role of nickel doping on structural, optical, magnetic properties and antibacterial activity of ZnO nanoparticles

    SciTech Connect

    Vijayaprasath, G.; Murugan, R.; Palanisamy, S.

    Highlights: • The XRD analyses revealed that the synthesizes nickel doped ZnO (Zn{sub 1−x}Ni{sub x}O, x = 0.0, 0.03, 0.06 and 0.09) nanostructures have hexagonal wurtzite structure. • The photoluminescence measurements revealed that the broad emission was composed of different bands due to zinc and oxygen vacancies. • X-ray photoelectron spectroscopy (XPS) confirmed the Ni incorporation in ZnO lattice as Ni{sup 2+} ions. • Room temperature ferromagnetism was observed due to the oxygen vacancies and zinc interstitials are the main reasons for ferromagnetism in Ni doped ZnO NPs. - Abstract: Zn{sub 1−x}Ni{sub x}O nanoparticles were synthesized by co-precipitation method. Themore » crystallite sizes of the synthesized samples found to decrease from 38 to 26 nm with increase in nickel concentration. FTIR spectra confirmed the presence of Zn−O stretching bands at 577, 573, 569 and 565 cm{sup −1} in the respective ZnO NPs. Optical absorption spectra revealed the red shifted and estimated band gap is found to decrease with increase of Ni doping concentration. The PL spectra of all the samples exhibited a broad emission at 390 nm in the visible range. The carriers (donors) bounded on the Ni sites were observed from the micro Raman spectroscopic studies. Pure and Ni doped ZnO NPs showed significant changes in the M–H loop, especially the diamagnetic behavior changed into ferromagnetic nature for Ni doped samples. The antiferromagnetic super-exchange interactions between Ni{sup 2+} ions is increased in higher Ni doped ZnO NPs and also their antibacterial activity has been studied.« less

  2. Effect of Ag/Al co-doping method on optically p-type ZnO nanowires synthesized by hot-walled pulsed laser deposition

    PubMed Central

    2012-01-01

    Silver and aluminum-co-doped zinc oxide (SAZO) nanowires (NWs) of 1, 3, and 5 at.% were grown on sapphire substrates. Low-temperature photoluminescence (PL) was studied experimentally to investigate the p-type behavior observed by the exciton bound to a neutral acceptor (A0X). The A0X was not observed in the 1 at.% SAZO NWs by low-temperature PL because 1 at.% SAZO NWs do not have a Ag-O chemical bonding as confirmed by XPS measurement. The activation energies (Ea) of the A0X were calculated to be about 18.14 and 19.77 meV for 3 and 5 at.% SAZO NWs, respectively, which are lower than the activation energy of single Ag-doped NW which is about 25 meV. These results indicate that Ag/Al co-doping method is a good candidate to make optically p-type ZnO NWs. PMID:22647319

  3. Integration of ZnO and CuO nanowires into a thermoelectric module

    PubMed Central

    Dalola, Simone; Faglia, Guido; Comini, Elisabetta; Ferroni, Matteo; Soldano, Caterina; Ferrari, Vittorio; Sberveglieri, Giorgio

    2014-01-01

    Summary Zinc oxide (ZnO, n-type) and copper oxide (CuO, p-type) nanowires have been synthesized and preliminarily investigated as innovative materials for the fabrication of a proof-of-concept thermoelectric device. The Seebeck coefficients, electrical conductivity and thermoelectric power factors (TPF) of both semiconductor materials have been determined independently using a custom experimental set-up, leading to results in agreement with available literature with potential improvement. Combining bundles of ZnO and CuO nanowires in a series of five thermocouples on alumina leads to a macroscopic prototype of a planar thermoelectric generator (TEG) unit. This demonstrates the possibility of further integration of metal oxide nanostructures into efficient thermoelectric devices. PMID:24991531

  4. Integration of ZnO and CuO nanowires into a thermoelectric module.

    PubMed

    Zappa, Dario; Dalola, Simone; Faglia, Guido; Comini, Elisabetta; Ferroni, Matteo; Soldano, Caterina; Ferrari, Vittorio; Sberveglieri, Giorgio

    2014-01-01

    Zinc oxide (ZnO, n-type) and copper oxide (CuO, p-type) nanowires have been synthesized and preliminarily investigated as innovative materials for the fabrication of a proof-of-concept thermoelectric device. The Seebeck coefficients, electrical conductivity and thermoelectric power factors (TPF) of both semiconductor materials have been determined independently using a custom experimental set-up, leading to results in agreement with available literature with potential improvement. Combining bundles of ZnO and CuO nanowires in a series of five thermocouples on alumina leads to a macroscopic prototype of a planar thermoelectric generator (TEG) unit. This demonstrates the possibility of further integration of metal oxide nanostructures into efficient thermoelectric devices.

  5. Fabrication of nanostructured electrodes and interfaces using combustion CVD

    NASA Astrophysics Data System (ADS)

    Liu, Ying

    -aligned ZnO nanorods, and two-dimensional ZnO flakes. Solid-state gas sensors based on single piece of these nanostructures demonstrated superior gas sensing performances. These size-tunable nanostructures could be the building blocks of or a template for fabrication of functional devices. In summary, this research has developed new ways for fabrication of high-performance solid-state ionic devices and has helped generating fundamental understanding of the correlation between processing conditions, microstructure, and properties of the synthesized structures.

  6. Electrosynthesis of ZnO nanorods and nanotowers: Morphology and X-ray Absorption Near Edge Spectroscopy studies

    NASA Astrophysics Data System (ADS)

    Sigircik, Gokmen; Erken, Ozge; Tuken, Tunc; Gumus, Cebrail; Ozkendir, Osman M.; Ufuktepe, Yuksel

    2015-06-01

    Deposition mechanism of nano-structured ZnO films has been investigated in the absence and presence of chloride ions from aqueous solution. The resulting opto-electronic properties were interpreted extensively, using X-ray diffraction (XRD), X-ray Absorption Near Edge Spectroscopy (XANES), field emission scanning electron microscopy (FE-SEM), UV-Visible spectroscopy and four probe techniques. The ZnO deposition is mass transport controlled process and the interaction of chloride ions with the surface has great influence on diffusion kinetics, considering the substantial species (Zn2+ and OH-) involved in the construction of ZnO film. This effect does not change major lattice parameters, as shown with detailed analysis of XRD data. However, the texture coefficient (Tc) (0 0 2) value is higher in presence of chloride ions containing synthesis solution which gave vertically aligned, well defined and uniformly dispersed nanorods structure. The calculated Eg values are in the range 3.28-3.41 eV and 3.22-3.31 eV for ZnO nanorods and nanotowers synthesized at different deposition periods, respectively. Furthermore, the charge mobility values regarding the deposition periods were measured to be in the ranges from 130.4 to 449.2 cm2 V-1 s-1 and 126.2 to 204.7 cm2 V-1 s-1 for nanorods and nanotowers, respectively. From XANES results, it was shown that the Zn K-edge spectrum is dominated by the transition of Zn 1s core electrons into the unoccupied Zn 4p states of the conduction band. Comparing the rod and tower nano-structured ZnO thin films, the excitation behavior of valence band electrons is different. Moreover, the density states of Zn 4p are higher for ZnO nanorods.

  7. Fabrication of hierarchical flower-like porous ZnO nanostructures from layered ZnC2O4·3Zn(OH)2 and gas sensing properties

    NASA Astrophysics Data System (ADS)

    Cui, Jiashan; Sun, Jianbo; Liu, Xin; Li, Jinwei; Ma, Xinzhi; Chen, Tingting

    2014-07-01

    ZnO materials with porous and hierarchical flower-like structure were synthesized through mild hydrothermal and simple calcination approach, in which the flower-like layered zinc oxalate hydroxide (ZnC2O4·3Zn(OH)2) precursor was first synthesized and then calcined at 600 °C. The obtained products were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopic (TEM), Brunauer-Emmett-Teller (BET) and thermogravimetric (TG) analysis. We proposed the possible growth mechanism of the material via studying the time evolution experiment results. In the process of reaction, oxalic acid as a structure-directing agent hydrolyzed and then formed primarily sheets-like intermediate ZnC2O4·2H2O. Hexamethylenetetramine (HMT) as surfactant, with directional adsorption, leads to the formation of layered zinc oxalate hydroxide precursor. Furthermore, the gas sensitivity also can be characterized, whose results indicated that the synthesized materials had a preferable selectivity to ethanol gas. The fast response rate and reversible performance can be attributed to the produced greater specific surface area produced, which was caused by the porous and hierarchical flower-like structure.

  8. Template-free hydrothermal synthesis of beaded nanochain bundles of ZnO and their application as photoanode in dye-sensitized solar cells

    NASA Astrophysics Data System (ADS)

    Ballal, Reshma; Shinde, Manish; Waghadkar, Yogesh; Arbuj, Sudhir; Rane, Sunit; Chauhan, Ratna

    2018-02-01

    ZnO shows promising candidature as photoanode material for dye-sensitized solar cells (DSSCs) due to its high bulk electron mobility and easily tailorable geometrical structures. The objective of this study is to facilitate the development of highly porous hierarchical ZnO for enhanced power conversion efficiency in dye-sensitized solar cells (DSSC) due to its greater dye adsorption. This study investigated the influence of reaction temperatures of 120 °C (sample Z-1) and 180 °C (sample Z-2) in hydrothermal synthesis on structural, morphological and optical properties of resultant ZnO nanostructures and their performance as photoanode material in DSSCs. The synthesized beaded nanochain bundles of ZnO, with multilayered and highly ordered texture, have diameters of several micrometers. Structural and morphological analysis shows that the ZnO beaded nanochain-like architectures possess wurtzite crystalline nature. These morphological improvements (beaded nanochains) of ZnO were found to exhibit higher dye loading and conversion efficiency due to increase in the surface area while reducing charge recombination. The maximum conversion efficiency was obtained with Z-1 and Z-2 is 2.95 and 3.56% with photocurrent of 7.73 and 9.24 mA/cm2, respectively. The obtained results pertaining to the DSSC performance studies were corroborated by the impedance spectroscopy data.

  9. Renewable Lignosulfonate-Assisted Synthesis of Hierarchical Nanoflake-Array-Flower ZnO Nanomaterials in Mixed Solvents and Their Photocatalytic Performance

    NASA Astrophysics Data System (ADS)

    Li, Yue; Zuo, Hong-Fen; Guo, Yuan-Ru; Miao, Ting-Ting; Pan, Qing-Jiang

    2016-05-01

    With the assistance of sodium lignosulfonate, hierarchical nanoflake-array-flower nanostructure of ZnO has been fabricated by a facile precipitation method in mixed solvents. The sodium lignosulfonate amount used in our synthetic route is able to fine-tune ZnO morphology and an abundance of pores have been observed in the nanoflake-array-flower ZnO, which result in specific surface area reaching as high as 82.9 m2 · g-1. The synthesized ZnO exhibits superior photocatalytic activity even under low-power UV illumination (6 W). It is conjectured that both nanoflake-array structure and plenty of pores embedded in ZnO flakes may provide scaffold microenvironments to enhance photocatalytic activity. Additionally, this catalyst can be used repeatedly without a significant loss in photocatalytic activity. The low-cost, simple synthetic approach as well as high photocatalytic and recycling efficiency of our ZnO nanomaterials allows for application to treat wastewater containing organic pollutants in an effective way.

  10. Investigation of intrinsic and extrinsic defects effective role on producing intense red emission in ZnO:Eu nanostructures

    SciTech Connect

    Najafi, Mehrdad, E-mail: najafi@shahroodut.ac.ir; Haratizadeh, Hamid

    2015-05-15

    Highlights: • Effective role of defects on producing red emission at indirect excitation. • V{sub Zn} and V{sub O} defects have important role on energy transfer. • Mg related defects and Zn{sub i} defects were responsible for blue emission. • Extrinsic and intrinsic defects mediated energy transfer to sensitize Eu{sup 3+} ions. • Decrease of red emission because of diminishing in oxygen vacancy. - Abstract: Europium doped ZnO nanorads and nanosheets were synthesized by hydrothermal method. Effects of Mg doping, morphology and annealing in oxygen ambient on structural and optical properties of ZnO nanostructures were investigated using X-ray diffraction (XRD),more » particle size analysis (PSA), thermo gravimetric analysis (TGA), differential thermal analysis (DTA), differential thermo gravimetry (DTG), scanning electron microscopy (SEM) and photoluminescence spectroscopy (PL). This study recommends that both of intrinsic and extrinsic defects facilitate energy transfer (ET) from the ZnO host to Eu{sup 3+} ions and consequently have efficient role on producing intense red emission at indirect excitation. The results also showed that annealing process improved the crystal structure of ZnO nanosheets due to decrease of surface defects; however decreased ET and red emission because of diminishing in oxygen vacancy. In addition in ZnO nanorods sample with more surface area in comparison with ZnO nanosheets sample deep level emissions are enhanced.« less

  11. A hetero-homogeneous investigation of chemical bath deposited Ga-doped ZnO nanorods

    NASA Astrophysics Data System (ADS)

    Rakhsha, Amir Hosein; Abdizadeh, Hossein; Pourshaban, Erfan; Golobostanfard, Mohammad Reza

    2018-01-01

    One-dimensional nanostructures of zinc oxide (ZnO) have been in the center of attention, mostly for electronic applications due to their distinctive properties such as high electron mobility (100 cm2V-1s-1) and crystallinity. Thanks to its high density of vacancies and interstitial sites, wurtzite lattice of ZnO is a suitable host for gallium (Ga) as a dopant element. Herein, ZnO nanorod arrays (NRAs) are synthesized by a low-temperature chemical bath deposition (CBD) method with various concentrations of gallium nitrate hydrate as a dopant precursor. Structural and morphological analyses confirm that optimum properties of gallium-doped ZnO (GZO) are obtained at 1% (Ga to Zn molar ratio). Owing to the replacement of smaller Ga3+ ions with Zn2+ ions in the GZO structure, a slight shift of (002) peak to higher angles could be observed in XRD pattern of GZO NRAs. The scanning electron microscope images demonstrate a proliferation in the ZnO NRAs length from 650 nm for undoped ZnO (UZO) to 1200 nm for GZO-1%. However, increasing the dopant concentration above 2.5% results in formation of homogeneous zinc gallium oxide in the bulk solution, which is a sign of inefficient process of doping in GZO NRAs. Furthermore, photoluminescence spectroscopy is used to characterize the band-gap variation of the samples, which demonstrates a small red-shift in the UV emission peak and a decrease in visible emission peak intensity with introducing Ga in ZnO lattice. Lower resistivity for GZO-1% (1.1 MΩ) sample compared to UZO (1.4 MΩ) is recorded, which is compelling evidence for the presence of Ga3+ in ZnO lattice. The results suggest that incorporating Ga into ZnO lattice using CBD method is an easy and effective technique to improve the electrical properties of ZnO NRAs that is an essential factor for a broad range of devices.

  12. High Performance Flexible Actuator of Urchin-Like ZnO Nanostructure/Polyvinylenefluoride Hybrid Thin Film with Graphene Electrodes for Acoustic Generator and Analyzer.

    PubMed

    Cheong, Oug Jae; Lee, James S; Kim, Jae Hyun; Jang, Jyongsik

    2016-05-01

    A bass frequency response enhanced flexible polyvinylidene fluoride (PVDF) based thin film acoustic actuator is successfully fabricated. High concentrations of various zinc oxide (ZnO) is embedded in PVDF matrix, enhancing the β phase content and the dielectric property of the composite thin film. ZnO acts as a nucleation agent for the crystallization of PVDF. A chemical vapor deposition grown graphene is used as electrodes, enabling high electron mobility for the distortion free acoustic signals. The frequency response of the fabricated acoustic actuator is studied as a function of the film thickness and filler content. The optimized film has a thickness of 80 μm with 30 wt% filler content and shows 72% and 42% frequency response enhancement in bass and midrange compared to the commercial PVDF, respectively. Also, the total harmonic distortion decreases to 82% and 74% in the bass and midrange regions, respectively. Furthermore, the composite film shows a promising potential for microphone applications. Most of all, it is demonstrated that acoustic actuator performance is strongly influenced by degree of PVDF crystalline. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  13. Electrochemical Sensing, Photocatalytic and Biological Activities of ZnO Nanoparticles: Synthesis via Green Chemistry Route

    NASA Astrophysics Data System (ADS)

    Yadav, L. S. Reddy; Archana, B.; Lingaraju, K.; Kavitha, C.; Suresh, D.; Nagabhushana, H.; Nagaraju, G.

    2016-05-01

    In this paper, we have successfully synthesized ZnO nanoparticles (Nps) via solution combustion method using sugarcane juice as the novel fuel. The structure and morphology of the synthesized ZnO Nps have been analyzed using various analytical tools. The synthesized ZnO Nps exhibit excellent photocatalytic activity for the degradation of methylene blue dye, indicating that the ZnO Nps are potential photocatalytic semiconductor materials. The synthesized ZnO Nps also show good electrochemical sensing of dopamine. ZnO Nps exhibit significant bactericidal activity against Klebsiella aerogenes, Pseudomonas aeruginosa, Eschesichia coli and Staphylococcus aureus using agar well diffusion method. Furthermore, the ZnO Nps show good antioxidant activity by potentially scavenging 1-diphenyl-2-picrylhydrazyl (DPPH) radicals. The above studies clearly demonstrate versatile applications of ZnO synthesized by simple eco-friendly route.

  14. Synthesis of hollow ZnO microspheres by an integrated autoclave and pyrolysis process.

    PubMed

    Duan, Jinxia; Huang, Xintang; Wang, Enke; Ai, Hanhua

    2006-03-28

    Hollow zinc oxide microspheres have been synthesized from a micro ZnBr2·2H2O precursor obtained by an autoclave process in bromoform steam at 220 °C /2.5 MPa. Field-emission scanning electron microscropy (FE-SEM) and transmission electron microscopy (TEM) show that the products are about 1.0 µm single crystal spherical particles with hollow interiors, partly open surfaces and walls self-assembled by ZnO nanoparticles. X-ray diffraction (XRD) analysis shows that the as-prepared ZnO hollow spheres are of a hexagonal phase structure. A possible formation mechanism is suggested on the basis of the shape evolution of ZnO nanostructures observed by SEM and TEM. The room-temperature photoluminescence (PL) spectrum shows UV emission around 386 nm and weak green emission peaks indicating that there are few defects in the single crystal grains of the ZnO microspheres.

  15. ZnO nanorods as catalyts for biodiesel production from olive oil

    NASA Astrophysics Data System (ADS)

    Molina, Carmen Maria Miralda

    The motivation to determine a viable alternative to petroleum based energy has risen in recent years due to increased greenhouse gas emissions, environmental pollution, and the fear of exhausting oil and natural gas reserves. Biodiesel derived from the transesterification of vegetable oils or animal fats has emerged as a viable alternative to petroleum diesel. However, for this to become an option available to the average consumer it is vital to find an effective catalyst. Metal oxides have emerged as potential heterogeneous catalysts. ZnO in particular is attractive because it is abundant. The use of nanostructures has been shown to improve the catalytic performance of ZnO. ZnO nanorods were synthesized using a solution approach. The crystalline structure, morphology, and surface area were confirmed using XRD, SEM, and BET surface area respectively. The characterized nanorods were used as catalysts for the production of biodiesel. The nanorods achieved conversions of 94.8% at 150°C for reaction times of eight hours. They also demonstrated better catalytic performance, attributed to their increased degree of crystallinity, than conventional ZnO. A kinetic study at 150°C to determine the reaction rate parameters was also conducted. Due to the presence of three distinct phases in the reaction, initially the reaction rate is dominated by mass transfer limitations. However, these are eventually overcome and the reaction proceeds with a pseudo-first order with respect to the oil and a reaction rate constant of 0.5136 h-1.

  16. Highly textured and transparent RF sputtered Eu2O3 doped ZnO films

    PubMed Central

    Sreedharan, Remadevi Sreeja; Ganesan, Vedachalaiyer; Sudarsanakumar, Chellappan Pillai; Bhavsar, Kaushalkumar; Prabhu, Radhakrishna; Mahadevan Pillai, Vellara Pappukutty Pillai

    2015-01-01

    Background Zinc oxide (ZnO) is a wide, direct band gap II-VI oxide semiconductor. ZnO has large exciton binding energy at room temperature, and it is a good host material for obtaining visible and infrared emission of various rare-earth ions. Methods Europium oxide (Eu2O3) doped ZnO films are prepared on quartz substrate using radio frequency (RF) magnetron sputtering with doping concentrations 0, 0.5, 1, 3 and 5 wt%. The films are annealed in air at a temperature of 773 K for 2 hours. The annealed films are characterized using X-ray diffraction (XRD), micro-Raman spectroscopy, atomic force microscopy, ultraviolet (UV)-visible spectroscopy and photoluminescence (PL) spectroscopy. Results XRD patterns show that the films are highly c-axis oriented exhibiting hexagonalwurtzite structure of ZnO. Particle size calculations using Debye-Scherrer formula show that average crystalline size is in the range 15–22 nm showing the nanostructured nature of the films. The observation of low- and high-frequency E2 modes in the Raman spectra supports the hexagonal wurtzite structure of ZnO in the films. The surface morphology of the Eu2O3 doped films presents dense distribution of grains. The films show good transparency in the visible region. The band gaps of the films are evaluated using Tauc plot model. Optical constants such as refractive index, dielectric constant, loss factor, and so on are calculated using the transmittance data. The PL spectra show both UV and visible emissions. Conclusion Highly textured, transparent, luminescent Eu2O3 doped ZnO films have been synthesized using RF magnetron sputtering. The good optical and structural properties and intense luminescence in the ultraviolet and visible regions from the films suggest their suitability for optoelectronic applications. PMID:25765728

  17. Highly Porous Thermoelectric Nanocomposites with LowThermalConductivityand High Figure of Merit from Large-Scale Solution-Synthesized Bi2Te2.5Se0.5HollowNanostructures

    DOE PAGES

    Xu, Biao; Ames Lab., Ames, IA; Feng, Tianli L.; ...

    2017-01-12

    In order to enhance the performance of thermoelectric materials and enable access to their widespread applications, it is beneficial yet challenging to synthesize hollow nanostructures in large quantities, with high porosity, low thermal conductivity (κ) and excellent figure of merit (z T). We report a scalable (ca. 11.0 g per batch) and low-temperature colloidal processing route for Bi 2Te 2.5Se 0.5 hollow nanostructures. They are sintered into porous, bulk nanocomposites (phi 10 mm×h 10 mm) with low κ (0.48 W m -1 K -1) and the highest z T (1.18) among state-of-the-art Bi 2Te 3-xSe x materilas. Additional benefits ofmore » the unprecedented low relative density (68–77 %) are the large demand reduction of raw materials and the improved portability. This method can be adopted to fabricate other porous phase-transition and thermoelectric chalcogenide materials and will pave the way for the implementation of hollow nanostructures in other fields.« less

  18. Highly Porous Thermoelectric Nanocomposites with Low Thermal Conductivity and High Figure of Merit from Large-Scale Solution-Synthesized Bi2 Te2.5 Se0.5 Hollow Nanostructures.

    PubMed

    Xu, Biao; Feng, Tianli; Agne, Matthias T; Zhou, Lin; Ruan, Xiulin; Snyder, G Jeffery; Wu, Yue

    2017-03-20

    To enhance the performance of thermoelectric materials and enable access to their widespread applications, it is beneficial yet challenging to synthesize hollow nanostructures in large quantities, with high porosity, low thermal conductivity (κ) and excellent figure of merit (z T). Herein we report a scalable (ca. 11.0 g per batch) and low-temperature colloidal processing route for Bi 2 Te 2.5 Se 0.5 hollow nanostructures. They are sintered into porous, bulk nanocomposites (phi 10 mm×h 10 mm) with low κ (0.48 W m -1  K -1 ) and the highest z T (1.18) among state-of-the-art Bi 2 Te 3-x Se x materilas. Additional benefits of the unprecedented low relative density (68-77 %) are the large demand reduction of raw materials and the improved portability. This method can be adopted to fabricate other porous phase-transition and thermoelectric chalcogenide materials and will pave the way for the implementation of hollow nanostructures in other fields. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  19. How the guest molecules in nanoporous Zn(II) metal-organic framework can prevent agglomeration of ZnO nanoparticles

    SciTech Connect

    Moeinian, Maryam; Akhbari, Kamran, E-mail: akhbari.k@khayam.ut.ac.ir

    The host and the apohost framework of [Zn{sub 2}(BDC){sub 2}(H{sub 2}O){sub 2}·(DMF){sub 2}]{sub n} (1·2H{sub 2}O·2DMF), (BDC{sup 2−}=benzene-1,4-dicarboxylate and DMF=N,N-Dimethylformamide), were synthesized and subsequently used for preparation of ZnO nanomaterials. With calcination of the host framework of 1·2H{sub 2}O·2DMF, ZnO nanoparticles were obtained. By the same process on the apohost framework of 1, agglomerated nanoparticles of ZnO were formed. These nano-structures were characterized by X-ray powder diffraction (XRD) and Scanning electron microscopy (SEM). These results indicate that with removal of the guest DMF and coordinated H{sub 2}O molecules from the one-dimensional channels of 1·2H{sub 2}O·2DMF, the tendency of nanoparticles tomore » agglomerate increases and the role of this MOF in preparation of ZnO nanoparticles from this precursor was reduced. - Graphical abstract: Nano-porous zinc(II) MOF with guest DMF and coordinated H{sub 2}O molecules has been synthesized and characterized. The host and the apohost framework of it were used for preparation of ZnO nanomaterials. The role of these species in preparation of ZnO nanoparticles from the host framework is probably similar to the role of polymeric stabilizers in formation of nanoparticles. - Highlights: • Nanoparticles of ZnO were fabricated from nanoporous metal-organic framework. • The effect of guest DMF and coordinated H{sub 2}O molecules on this process was studied. • The effect of them in formation nanoparticle is similar to polymeric stabilizers.« less

  20. A detailed study on Sn4+ doped ZnO for enhanced photocatalytic degradation

    NASA Astrophysics Data System (ADS)

    Beura, Rosalin; Pachaiappan, R.; Thangadurai, P.

    2018-03-01

    The samples of Sn4+ doped (1, 5, 10, 15, 20 & 30%) ZnO nanostructures were synthesized by a low temperature hydrothermal method. Structural analysis by XRD and Raman spectroscopy showed the hexagonal wurtzite phase of ZnO and the formation of a secondary phase Zn2SnO4 beyond 10% doping of Sn4+. Microstructural analysis by TEM also confirmed the wurtzite ZnO with rod as well as particle like structure. Presence of various functional groups (sbnd OH, sbnd CH, Znsbnd O) were confirmed by FTIR. Optical properties were studied by UV-vis absorption, photoluminescence emission spectroscopies and lifetime measurement. Band gap of the undoped and Sn4+ doped ZnO were analyzed by Tauc plot and it was observed that the band gap of the materials had slightly decreased from 3.2 to 3.16 eV and again increased to 3.23 eV with respect to the increase in the doping concentration from 1 to 30%. A significant change was also noticed in the photoluminescence emission properties of ZnO i.e. increase in the intensity of NBE emission and decrease in DLE, on subject to Sn4+ doping. Average PL lifetime had increased from 29.45 ns for ZnO to 30.62 ns upon 1% Sn ion doping in ZnO. Electrical properties studied by solid state impedance spectroscopy showed that the conductivity had increased by one order of magnitude (from 7.48×10-8 to 2.21×10-7 S/cm) on Sn4+ doping. Photocatalytic experiments were performed on methyl orange (MO) as a model industrial dye under UV light irradiation for different irradiation times. The optimum Sn4+ content in order to achieve highest photocatalytic activity was found to be 1% Sn 4+ doping. The enhancement was achieved due to a decrease in the band gap favoring the generation of electron-hole pairs and the enhanced PL life time that delays the recombination of these charge carrier formation. The third reason was that the increased electrical conductivity that indicated the faster charge transfer in this material to enhance the photocatalytic activity. The Sn

  1. Carbon-coated ZnO mat passivation by atomic-layer-deposited HfO2 as an anode material for lithium-ion batteries.

    PubMed

    Jung, Mi-Hee

    2017-11-01

    ZnO has had little consideration as an anode material in lithium-ion batteries compared with other transition-metal oxides due to its inherent poor electrical conductivity and large volume expansion upon cycling and pulverization of ZnO-based electrodes. A logical design and facile synthesis of ZnO with well-controlled particle sizes and a specific morphology is essential to improving the performance of ZnO in lithium-ion batteries. In this paper, a simple approach is reported that uses a cation surfactant and a chelating agent to synthesize three-dimensional hierarchical nanostructured carbon-coated ZnO mats, in which the ZnO mats are composed of stacked individual ZnO nanowires and form well-defined nanoporous structures with high surface areas. In order to improve the performance of lithium-ion batteries, HfO 2 is deposited on the carbon-coated ZnO mat electrode via atomic layer deposition. Lithium-ion battery devices based on the carbon-coated ZnO mat passivation by atomic layer deposited HfO 2 exhibit an excellent initial discharge and charge capacities of 2684.01 and 963.21mAhg -1 , respectively, at a current density of 100mAg -1 in the voltage range of 0.01-3V. They also exhibit cycle stability after 125 cycles with a capacity of 740mAhg -1 and a remarkable rate capability. Copyright © 2017 Elsevier Inc. All rights reserved.

  2. New approach to biosensing of co-enzyme nicotinamide adenine dinucleotide (NADH) by incorporation of neutral red in aluminum doped nanostructured ZnO thin films.

    PubMed

    V T, Fidal; T S, Chandra

    2017-06-01

    Biosensing of NADH on bare electrodes has drawbacks such as high over-potential and poisoning during the oxidation reaction. To overcome this challenge a different approach has been undertaken by incorporating neutral red (NR) in Al doped ZnO (AZO) thin films using one-pot chemical bath deposition (CBD). The surface morphology of the films was hexagonal nanorods along the c-axis, perpendicular to the substrate. The thickness of the thin films were ranging from 400 to 3000nm varying dependent on time of deposition (30 to 150min). The average diameter of the nanorods was larger in the presence of neutral red (NR-AZO) with ~300nm in contrast to its absence (AZO) with ~200nm. The density of the packing of nanorods was dependent on the citrate concentration used during deposition. Control over the dopant concentration in the films was achieved by varying the area of Al foil used in the deposition solution. The selected area diffraction (SAED) and X-ray diffraction (XRD) indicated 002 plane of orientation in the nanorods. FTIR and FT-Raman analysis revealed conserved structure of NR and AZO. Chronoamperometric (CA) analysis showed a sensitivity of 0.45μAcm -2 mM -1 and LoD of 22μM within the range 0.075-4mM of NADH. The biological sensing of NADH was validated by physical adsorption of NAD + dependent-lactate dehydrogenase (LDH) on NR-AZO. CA showed sensitivity of 0.56μAcm -2 mM -1 and LoD for lactate was 27μM in the range of 0.1-1mM of lactate. Further validation with real-time serum sample shows that LDH/NR-AZO correlates with the clinical values. The distinction in this study is that the organic mediator like neutral red has been incorporated into the grain structure of the ZnO thin film whereas other study with the mediators have only attempted surface functionalization. This article is part of a Special Issue entitled "Recent Advances in Bionanomaterials" Guest Editor: Dr. Marie-Louise Saboungi and Dr. Samuel D. Bader. Copyright © 2017 Elsevier B.V. All rights

  3. Electrochemical Study and Characterization of an Amperometric Biosensor Based on the Immobilization of Laccase in a Nanostructure of TiO₂ Synthesized by the Sol-Gel Method.

    PubMed

    Romero-Arcos, Mariana; Garnica-Romo, Ma Guadalupe; Martínez-Flores, Héctor Eduardo

    2016-07-07

    Laccase amperometric biosensors were developed to detect the catechol compound. The laccase enzyme (LAC) immobilization was performed on nanostructures of (a) titania (TiO₂); (b) titania/Nafion (TiO₂/NAF) (both immobilized by the sol-gel method) and a third nanostructure, which consisted of a single biosensor composite of Nafion and laccase enzyme denoted as NAF/LAC. The Nafion was deposited on a graphite electrode and used to avoid "cracking" on the matrix. The TiO₂ particle size was an average of 66 nm. FTIR spectroscopy vibration modes of different composites were determined. The electrochemical behavior of the biosensor was studied using electrochemical spectroscopy (EIS) and cyclic voltammetry (CV). The biosensor based on TiO₂/NAF/LAC presented the best electro-chemical properties with regard to sensitivity, stability and detection limit after a period of 22 days.

  4. Synthesis of ZnO nanorods and their application in the construction of a nanostructure-based electrochemical sensor for determination of levodopa in the presence of carbidopa.

    PubMed

    Molaakbari, Elahe; Mostafavi, Ali; Beitollahi, Hadi; Alizadeh, Reza

    2014-09-07

    A novel carbon paste electrode modified with ZnO nanorods and 5-(4'-amino-3'-hydroxy-biphenyl-4-yl)-acrylic acid (3,4'-AAZCPE) was fabricated. The electrochemical study of the modified electrode, as well as its efficiency for the electrocatalytic oxidation of levodopa, is described. The electrode was employed to study the electrocatalytic oxidation of levodopa, using cyclic voltammetry (CV), chronoamperometry (CHA), and square-wave voltammetry (SWV) as diagnostic techniques. It has been found that the oxidation of levodopa at the surface of the modified electrode occurs at a potential of about 370 mV less positive than that of an unmodified carbon paste electrode. The SWV results exhibit a linear dynamic range from 1.0 × 10(-7) M to 7.0 × 10(-5) M and a detection limit of 3.5 × 10(-8) M for levodopa. In addition, this modified electrode was used for the simultaneous determination of levodopa and carbidopa. Finally, the modified electrode was used for the determination of levodopa and carbidopa in some real samples.

  5. Study of morphology effects on magnetic interactions and band gap variations for 3d late transition metal bi-doped ZnO nanostructures by hybrid DFT calculations

    SciTech Connect

    Datta, Soumendu, E-mail: soumendu@bose.res.in; Baral, Sayan; Mookerjee, Abhijit

    2015-08-28

    Using density functional theory (DFT) based electronic structure calculations, the effects of morphology of semiconducting nanostructures on the magnetic interaction between two magnetic dopant atoms as well as a possibility of tuning band gaps have been studied in the case of the bi-doped (ZnO){sub 24} nanostructures with the impurity dopant atoms of the 3d late transition metals—Mn, Fe, Co, Ni, and Cu. To explore the morphology effect, three different structures of the host (ZnO){sub 24} nano-system, having different degrees of spatial confinement, have been considered: a two dimensional nanosheet, a one dimensional nanotube, and a finite cage-shaped nanocluster. The presentmore » study employs hybrid density functional theory to accurately describe the electronic structure of all the systems. It is shown here that the magnetic coupling between the two dopant atoms remains mostly anti-ferromagnetic in the course of changing the morphology from the sheet geometry to the cage-shaped geometry of the host systems, except for the case of energetically most stable bi-Mn doping, which shows a transition from ferromagnetic to anti-ferromagnetic coupling with decreasing aspect ratio of the host system. The effect of the shape change, however, has a significant effect on the overall band gap variations of both the pristine as well as all the bi-doped systems, irrespective of the nature of the dopant atoms and provides a means for easy tunability of their optoelectronic properties.« less

  6. Photophysical study of the interaction between ZnO nanoparticles and globular protein bovine serum albumin in solution and in a layer-by-layer self-assembled film

    NASA Astrophysics Data System (ADS)

    Hansda, Chaitali; Maiti, Pradip; Singha, Tanmoy; Pal, Manisha; Hussain, Syed Arshad; Paul, Sharmistha; Paul, Pabitra Kumar

    2018-10-01

    In this study, we investigated the spectroscopic properties of the water-soluble globular protein bovine serum albumin (BSA) while interacting with zinc oxide (ZnO) semiconductor nanoparticles (NPs) in aqueous medium and in a ZnO/BSA layer-by-layer (LbL) self-assembled film fabricated on poly (acrylic acid) (PAA)-coated quartz or a Si substrate via electrostatic interactions. BSA formed a ground state complex due to its interaction with ZnO NPs, which was confirmed by ultraviolet-visible absorption, and steady state and time-resolved fluorescence emission spectroscopic techniques. However, due to its interaction with ZnO, the photophysical properties of BSA depend significantly on the concentration of ZnO NPs in the mixed solution. The quenching of the fluorescence intensity of BSA in the presence of ZnO NPs was due to the interaction between ZnO and BSA, and the formation of their stable ground state complex, as well as energy transfer from the excited BSA to ZnO NPs in the complex nano-bioconjugated species. Multilayer growth of the ZnO/BSA LbL self-assembled film on the quartz substrate was confirmed by monitoring the characteristic absorption band of BSA (280 nm), where the nature of the film growth depends on the number of bilayers deposited on the quartz substrate. BSA formed a well-ordered molecular network-type morphology due to its adsorption onto the surface of the ZnO nanostructure in the backbone of the PAA-coated Si substrate in the LbL film according to atomic force microscopic study. The as-synthesized ZnO NPs were characterized by field emission scanning electron microscopy, X-ray powder diffraction, and dynamic light scattering techniques.

  7. Zinc oxide nanostructures for electrochemical cortisol biosensing

    NASA Astrophysics Data System (ADS)

    Vabbina, Phani Kiran; Kaushik, Ajeet; Tracy, Kathryn; Bhansali, Shekhar; Pala, Nezih

    2014-05-01

    In this paper, we report on fabrication of a label free, highly sensitive and selective electrochemical cortisol immunosensors using one dimensional (1D) ZnO nanorods (ZnO-NRs) and two dimensional nanoflakes (ZnO-NFs) as immobilizing matrix. The synthesized ZnO nanostructures (NSs) were characterized using scanning electron microscopy (SEM), selective area diffraction (SAED) and photoluminescence spectra (PL) which showed that both ZnO-NRs and ZnO-NFs are single crystalline and oriented in [0001] direction. Anti-cortisol antibody (Anti-Cab) are used as primary capture antibodies to detect cortisol using electrochemical impedance spectroscopy (EIS). The charge transfer resistance increases linearly with increase in cortisol concentration and exhibits a sensitivity of 3.078 KΩ. M-1 for ZnO-NRs and 540 Ω. M -1 for ZnO-NFs. The developed ZnO-NSs based immunosensor is capable of detecting cortisol at 1 pM. The observed sensing parameters are in physiological range. The developed sensors can be integrated with microfluidic system and miniaturized potentiostat to detect cortisol at point-of-care.

  8. Synthesis and gas sensing properties of α-Fe(2)O(3)@ZnO core-shell nanospindles.

    PubMed

    Zhang, Jun; Liu, Xianghong; Wang, Liwei; Yang, Taili; Guo, Xianzhi; Wu, Shihua; Wang, Shurong; Zhang, Shoumin

    2011-05-06

    α-Fe(2)O(3)@ZnO core-shell nanospindles were synthesized via a two-step hydrothermal approach, and characterized by means of SEM/TEM/XRD/XPS. The ZnO shell coated on the nanospindles has a thickness of 10-15 nm. Considering that both α-Fe(2)O(3) and ZnO are good sensing materials, we have investigated the gas sensing performances of the core-shell nanocomposite using ethanol as the main probe gas. It is interesting to find that the gas sensor properties of the core-shell nanospindles are significantly enhanced compared with pristine α-Fe(2)O(3). The enhanced sensor properties are attributed to the unique core-shell nanostructure. The detailed sensing mechanism is discussed with respect to the energy band structure and the electron depletion theory. The core-shell nanostructure reported in this work provides a new path to fabricate highly sensitive materials for gas sensing applications.

  9. Fabrication of high responsivity deep UV photo-detector based on Na doped ZnO nanocolumns

    NASA Astrophysics Data System (ADS)

    Agrawal, Jitesh; Dixit, Tejendra; Palani, I. A.; Ramachandra Rao, M. S.; Singh, Vipul

    2018-05-01

    We report a variety of the hydrothermally synthesized ZnO nanostructures with a significant suppression in defect-related emission and huge enhancement in the photo-current to the dark current ratio (approximately six orders of magnitude) upon UV light illumination. Interestingly, the photo-detector shows lower dark current of 1.6 nA with high responsivity of 507 A W‑1 at 254 nm. Here, a systematic analysis of the growth process as well as the physical, chemical and electrical properties of as-grown ZnO nanostructures has been performed. We have utilized the duo effect of both the inorganic (KMnO4) and organic (Na3C6H5O7) additives, which has facilitated the precise tuning of the morphology and intrinsic defects in nanostructures that have made an impact on the photo-responsivity, photoluminescence (PL) and adhesivity of the film on to the underlying substrate. PL analysis of as-grown ZnO nanostructures has suggested 11 times improvement in the near band emission (NBE) to defect level emission (DLE) ratio. Interestingly, thermal annealing of the samples has shown a dramatic change in the morphology with significant improvement in the crystallinity. Notably, the band gap was observed to be modulated from 3.3 eV to 3.1 eV after annealing. In addition to UV photo-detector based applications, the work presented here has provided a subtle solution towards the rectification of various problems pertaining to hydrothermal processes like poor adhesivity, feeble UV emission and problem in precise tuning of the morphology along with the bandgap in one go. Therefore, these investigations assume critical significance towards the development of next-generation optoelectronic devices.

  10. Effect of Long Selenization Time on Co Films under a Low Temperature of 300 °C to Synthesize a Nanostructure CoSe2 and Optical Properties

    NASA Astrophysics Data System (ADS)

    Wu, Po-Feng; Shi, Jen-Bin; Cheng, Bo-Ci; Wu, Cheng-Han; Lee, Hsuan-Wei; Lin, Hsien-Sheng; Cheng, Fu-Chou; Chen, Kuan-Ping

    2018-05-01

    This work investigates a simple and non-toxic method to transform pre-deposited amorphous Co film into CoSe2 films at a fixed, low temperature of 300 °C. Single CoSe2-phase films having good crystallinity were obtained at a selenisation time ≧ 24 hours. A nanostructure CoSe2 having two different nano-morphological layers was observed. The CoSe2 films (72 hours) observed a large absorption and a direct band gap.

  11. Efficient photocatalytic performance enhancement in Co-doped ZnO nanowires coupled with CuS nanoparticles

    NASA Astrophysics Data System (ADS)

    Li, Wei; Wang, Guojing; Feng, Yimeng; Li, Zhengcao

    2018-01-01

    In this research, a kind of highly efficient semiconductor photocatalyst was fabricated by depositing CuS nanoparticles uniformly on the surface of Co-doped ZnO nanowires. ZnO nanowires were synthesized by hydrothermal method and CuS nanoparticles were modified by successive ionic layer adsorption and reaction (SILAR). By conducting methyl orange (MO) degradation experiments under the illumination of visible light, the photocatalytic activity of Co-doped ZnO nanowires modified with CuS nanoparticles was found to be nearly three times active when compared to bare ZnO nanowires. Its superior photocatalytic performance has two main reasons. The doped Co2+ ions can inhibit the recombination of photo-generated electron-hole pairs and decrease the optical bandgap, while the p-n heterostructure can enhance the visible light absorption ability and promote the separation of photo-excited charge carriers. Furthermore, the effect of the amount of deposited CuS nanoparticles on the photocatalysis was also investigated. The photocatalytic efficiency firstly raised along with the increment of SILAR cycle times and reached a maximum at 10 cycles but then decreased as the cycle times continue to increase. This originates from that an excessive amount of CuS would not only cover the active reacting sites, but also serve as recombination centers. Overall, this new nanostructure is expected to work as an efficient photocatalyst.

  12. Effect of Ni doping on structural and optical properties of Zn{sub 1−x}Ni{sub x}O nanopowder synthesized via low cost sono-chemical method

    SciTech Connect

    Singh, Budhendra, E-mail: bksingh@ua.pt; Kaushal, Ajay, E-mail: ajay.kaushal@ua.pt; Bdikin, Igor

    2015-10-15

    Highlights: • Pure and Ni doped ZnO nanopowders were synthesized by low cost sonochemical method. • The optical properties of Zn{sub 1−x}Ni{sub x}O nanopowders can be tuned by varying Ni content. • The results reveal the solubility limit of Ni into ZnO matrix as below 8%. - Abstract: Zn{sub 1−x}Ni{sub x}O nanopowders with different Ni contents of x = 0.0, 0.04 and 0.08 were synthesized via cost effective sonochemical reaction method. X-ray diffraction (XRD) pattern reveals pure wurtzite phase of prepared nanostructures with no additional impurity peaks. The morphology and dimensions of nanoparticles were investigated using scanning electron microscope (SEM).more » A sharp and strong peak for first order optical mode for wurtzite zinc oxide (ZnO) structure was observed at ∼438 cm{sup −1} in Raman spectra. The calculated optical band gap (E{sub g}) from UV–vis transmission data was found to decrease with increase in Ni content. The observed red shift in E{sub g} with increasing Ni content in ZnO nanopowders were in agreement with band gap behaviours found in their photoluminescence (PL) spectra. The synthesised ZnO nanopowders with controlled band gap on Ni doping reveals their potential for use in various electronic and optical device applications. The results were discussed in detail.« less

  13. Influence of Doping and Nanostructuration on n-Type Bi2(Te0.8Se0.2)3 Alloys Synthesized by Arc Melting

    NASA Astrophysics Data System (ADS)

    Gharsallah, Mouna; Serrano-Sanchez, Federico; Nemes, Norbert M.; Martinez, Jose Luis; Alonso, Jose Antonio

    2017-01-01

    In competitive thermoelectric devices for energy conversion and generation, high-efficiency materials of both n-type and p-type are required. For this, Bi2Te3-based alloys have the best thermoelectric properties in room temperature applications. Partial replacement of tellurium by selenium is expected to introduce new donor states in the band gap, which would alter electrical conductivity and thermopower. We report on the preparation of n-type Bi2(Te1-xSex)3 solid solutions by a straightforward arc-melting technique, yielding nanostructured polycrystalline pellets. X-ray and neutron powder diffraction was used to assess Se inclusion, also indicating that the interactions between quintuple layers constituting this material are weakened upon Se doping, while the covalency of intralayer bonds is augmented. Moreover, scanning electron microscopy shows large surfaces perpendicular to the c crystallographic axis assembled as stacked sheets. Grain boundaries related to this 2D nanostructuration affect the thermal conductivity reducing it below 0.8 Wm-1K-1 at room temperature. Furthermore, Se doping increases the absolute Seebeck coefficient up to -140 μV K-1 at 400 K, which is also beneficial for improved thermoelectric efficiency.

  14. Luminescence properties of rare earth doped metal oxide nanostructures: A case of Eu-ZnO

    SciTech Connect

    Sahu, D.; Acharya, B. S.; Panda, N. R., E-mail: nihar@iitbbs.ac.in

    2016-05-06

    The present study reports the growth and luminescence properties of Eu doped ZnO nanostructures. The experiment has been carried out by synthesizing the materials by simple wet-chemical method. X-ray diffraction (XRD) studies show expansion of ZnO lattice with the incorporation of Eu ions which has been confirmed from the appearance of Eu{sub 2}O{sub 3} as a minor phase in the XRD pattern. The estimation of crystallite size from XRD results matches closely with the results obtained from transmission electron microscopy. Further, these results show the formation of nanosized Eu-ZnO particles of average size around 60 nm stacked on each other. FTIRmore » studies show the presence of both Zn-O and Eu-O modes in the spectra supporting the results obtained from XRD. The interesting results obtained from photoluminescence (PL) measurements show the presence of both band edge emission in UV region and the defect emissions in violet, blue and green region. The appearance of {sup 5}D{sub 0}→{sup 7}F{sub J} transitions of Eu{sup 3+} ions in red region clearly suggests the possible occurrence of energy transfer between the energy states of ZnO host and Eu{sup 3+} ions.« less

  15. Theory and Device Modeling for Nano-Structured Transistor Channels

    DTIC Science & Technology

    2011-06-01

    zinc oxide ( ZnO ) thin film transistors ( TFTs ) that contain nanocrystalline grains on the order of ~20nm. The authors of ref. 1 present results...problem in order to determine the threshold voltage. 15. SUBJECT TERMS nano-structured transistor , mesoscopic, zinc oxide , ZnO , field-effect...and R. Neidhard, “Microwave ZnO Thin - Film Transistors ”, IEEE Electron Dev. Lett. 29, 1024 (2008); doi: 10.1109/LED.2008.2001635.

  16. Synthesis and Characterization of Nano-Structure Metal Oxides and Peroxides Prepared by Laser Ablation in Liquids

    NASA Astrophysics Data System (ADS)

    Drmosh, Qasem Ahmed Qasem

    Pulsed laser ablation technique was applied for synthesize of ZnO, ZnO 2 and SnO2 nanostructure using metallic target in different liquids. For this purpose, a laser emitting pulsed UV radiations generated by the third harmonic of Nd:YAG (λ= 355 nm) was applied. For the synthesis of ZnO nanoparticles (NPs), a high-purity metallic plate of Zn was fixed at the bottom of a glass cell in the presence of deionized water and was irradiated at different laser energies (80- 100- 120) mJ per pulse. The average sizes and lattice parameters of ZnO produced by this method were estimated by X-ray diffraction (XRD). ZnO nanoparticles were also produced by ablation of zinc target in the presence of deionized water mixed with two types of surfactants: cetyltrimethyl ammonium bromide (CTAB) and octaethylene glycol monododecyl (OGM). The results showed that the average grain sizes decreased from 38 nm in the case of deionized water to 27 nm and 19 nm in CTAB and OGM respectively. The PL emission in CTAB and OGM showed two peaks: the sharp UV emission at 380 nm and a broad visible peak ranging from 450 nm to 600 nm. Zinc peroxide (ZnO2) nanoparticles having grain size less than 5 nm were also synthesized using pulsed laser ablation in aqueous solution in the presence of different surfactants and solid zinc target in 3 % hydrogen peroxide H2O2 for the first time. The effect of surfactants on the optical and structure of ZnO2 was studied by applying different spectroscopic techniques. The presence of the cubic phase of zinc peroxide in all samples was confirmed with XRD, and the grain sizes were 4.7 nm, 3.7 nm, 3.3 nm and 2.8 nm in pure H2O2; and H2O 2 mixed with SDS, CTAB and OGM respectively. For optical characterization, FTIR transmittance spectra of ZnO2 nanoparticles prepared with and without surfactants showed characteristic peaks of ZnO2 absorption at 435-445 cm-1. FTIR spectrum also revealed that the adsorbed surfactants on zinc peroxide disappeared in case of CTAB and OGM

  17. Enhanced photoelectrochemical and optical performance of ZnO films tuned by Cr doping

    NASA Astrophysics Data System (ADS)

    Salem, M.; Akir, S.; Massoudi, I.; Litaiem, Y.; Gaidi, M.; Khirouni, K.

    2017-04-01

    In this paper, pure and Cr-doped nanostructured Zinc oxide thin films were synthesized by simple and low cost co-precipitation and spin-coating method with Cr concentration varying between 0.5 and 5 at.%. Crystalline structure of the prepared films was investigated by X-ray diffraction (XRD) and Raman spectroscopy techniques. XRD analysis indicated that the films were indexed as the hexagonal phase of wurtzite-type structure and demonstrated a decrease in the crystallite size with increasing Cr doping content. Cr doping revealed a significant effect on the optical measurements such as transmission and photoluminescence properties. The optical measurements indicated that Cr doping decreases the optical band gap and it has been shifted from 3.41 eV for pure ZnO film to 3.31 eV for 5 at.% Cr-doped one. The photoelectrochemical (PEC) sensing characteristics of Cr-doped ZnO layers were investigated. Amongst all photo-anodes with different Cr dopant concentration, the 2 at.% Cr incorporated ZnO films exhibited fast response and higher photoconduction sensitivity.

  18. Core/shell structured Zn/ZnO nanoparticles synthesized by gaseous laser ablation with enhanced photocatalysis efficiency

    NASA Astrophysics Data System (ADS)

    Song, Lu; Wang, Yafei; Ma, Jing; Zhang, Qinghua; Shen, Zhijian

    2018-06-01

    Zinc oxide (ZnO) is a competitive candidate in semiconductor photocatalysts, only if the efficiency could be fully optimized especially by tailored nanostructures. Here we report a kind of core/shell structured Zn/ZnO nanoparticles with enhanced photocatalysis efficiency, which were synthesized by a highly-productive gaseous laser ablation method. The nanodroplets generated by laser ablation would be reduced to zinc in the protective atmosphere, and further be oxidized at surface to form a specific core/shell structured Zn/ZnO nanoparticles within seconds. Thanks to the formation of this Zn-ZnO Schottky junction, the photocatalysis degradation efficiency of such core/shell Zn/ZnO nanostructure is significantly improved owing to the enhanced visible light absorption and inhibited carrier recombination by introducing the metallic zinc.

  19. Amino acid-assisted synthesis of zinc oxide nanostructures

    NASA Astrophysics Data System (ADS)

    Singh, Baljinder; Moudgil, Lovika; Singh, Gurinder; Kaura, Aman

    2018-05-01

    In this manuscript we have used experimental approach that can provide a fundamental knowledge about the role played by biomolecules in designing the shape of nanostructure (NS) at a microscopic level. The three different amino acids (AAs) - Arginine (Arg), Aspartic acid (Asp) and Histidine (His) coated Zinc oxide (ZnO) NSs to explain the growth mechanism of nanoparticles of different shapes. Based on the experimental methodology we propose that AA-ZnO (Asp and Arg) nanomaterials could form of rod like configuration and His-ZnO NPs could form tablet like configuration. The synthesized samples are characterized using transmission electron microscopy (TEM) and X-ray diffraction (XRD). Results reveal that AAs are responsible for formation of different NSs

  20. Investigations of inorganic and hybrid inorganic-organic nanostructures

    NASA Astrophysics Data System (ADS)

    Kam, Kinson Chihang

    This thesis focuses on the exploratory synthesis and characterization of inorganic and hybrid inorganic-organic nanomaterials. In particular, nanostructures of semiconducting nitrides and oxides, and hybrid systems of nanowire-polymer composites and framework materials, are investigated. These materials are characterized by a variety of techniques for structure, composition, morphology, surface area, optical properties, and electrical properties. In the study of inorganic nanomaterials, gallium nitride (GaN), indium oxide (In2O3), and vanadium dioxide (VO2) nanostructures were synthesized using different strategies and their physical properties were examined. GaN nanostructures were obtained from various synthetic routes. Solid-state ammonolysis of metastable gamma-Ga2O 3 nanoparticles was found to be particularly successful; they achieved high surface areas and photoluminescent study showed a blue shift in emission as a result of surface and size defects. Similarly, In2O3 nanostructures were obtained by carbon-assisted solid-state syntheses. The sub-oxidic species, which are generated via a self-catalyzed vapor-liquid-solid mechanism, resulted in 1D nanostructures including nanowires, nanotrees, and nanobouquets upon oxidation. On the other hand, hydrothermal methods were used to obtain VO2 nanorods. After post-thermal treatment, infrared spectroscopy demonstrated that these nanorods exhibit a thermochromic transition with temperature that is higher by ˜10°C compared to the parent material. The thermochromic behavior indicated a semiconductor-to-metal transition associated with a structural transformation from monoclinic to rutile. The hybrid systems, on the other hand, enabled their properties to be tunable. In nanowire-polymer composites, zinc oxide (ZnO) and silver (Ag) nanowires were synthesized and incorporated into polyaniline (PANI) and polypyrrole (PPy) via in-situ and ex-situ polymerization method. The electrical properties of these composites are

  1. Tunable UV- and Visible-Light Photoresponse Based on p-ZnO Nanostructures/n-ZnO/Glass Peppered with Au Nanoparticles.

    PubMed

    Hsu, Cheng-Liang; Lin, Yu-Hong; Wang, Liang-Kai; Hsueh, Ting-Jen; Chang, Sheng-Po; Chang, Shoou-Jinn

    2017-05-03

    UV- and visible-light photoresponse was achieved via p-type K-doped ZnO nanowires and nanosheets that were hydrothermally synthesized on an n-ZnO/glass substrate and peppered with Au nanoparticles. The K content of the p-ZnO nanostructures was 0.36 atom %. The UV- and visible-light photoresponse of the p-ZnO nanostructures/n-ZnO sample was roughly 2 times higher than that of the ZnO nanowires. The Au nanoparticles of various densities and diameter sizes were deposited on the p-ZnO nanostructures/n-ZnO samples by a simple UV photochemical reaction method yielding a tunable and enhanced UV- and visible-light photoresponse. The maximum UV and visible photoresponse of the Au nanoparticle sample was obtained when the diameter size of the Au nanoparticle was approximately 5-35 nm. On the basis of the localized surface plasmon resonance effect, the UV, blue, and green photocurrent/dark current ratios of Au nanoparticle/p-ZnO nanostructures/n-ZnO are ∼1165, ∼94.6, and ∼9.7, respectively.

  2. A study on different morphological structures of zinc oxide nanostructures for humidity sensing application

    SciTech Connect

    Ismail, A. S., E-mail: kyrin-samaxi@yahoo.com; Mamat, M. H., E-mail: mhmamat@salam.uitm.edu.my; Rusop, M., E-mail: rusop@salam.uitm.my

    2016-07-06

    Effects of different morphological structures of ZnO to the performance of the device in the humidity sensing have been studied. Two different kinds of nanostructures were obtained which are nanords and nanoflakes. From the surface morphology image, the ZnO nanoflakes has lower diameter size of 100 nm compared to ZnO nanorods of 250 nm. The ZnO nanoflakes are not aligned and has low porous structure compared to ZnO nanorods. The humidity sensor performance of ZnO nanorods has superior performance compared to ZnO nanoflakes. The sensitivity of the ZnO nanorods sensor is 3.20 which are almost two times higher than themore » ZnO nanoflakes of 1.65. The structural properties of the samples have been characterized using field emission scanning electron microscopy (FESEM) electrical properties has been characterized using current voltage (I-V) measurement.« less

  3. Ag-ZnO nanostructure for ANTA explosive molecule detection

    SciTech Connect

    Shaik, Ummar Pasha; Sangani, L. D. Varma; Gaur, Anshu

    2016-05-23

    Ag/ZnO nanostructure for surface enhanced Raman scattering application in the detection of ANTA explosive molecule is demonstrated. A highly rough ZnO microstructure was achieved by rapid thermal annealing of metallic Zn film. Different thickness Ag nanostructures are decorated over these ZnO microstructures by ion beam sputtering technique. Surface enhanced Raman spectroscopic studies carried out over Ag/ZnO substrates have shown three orders higher enhancement compared to bare Ag nanostructure deposited on the same substrate. The reasons behind such huge enhancement are discussed based on the morphology of the sample.

  4. High-capacity cathodes for lithium-ion batteries from nanostructured LiFePO4 synthesized by highly-flexible and scalable flame spray pyrolysis

    NASA Astrophysics Data System (ADS)

    Hamid, N. A.; Wennig, S.; Hardt, S.; Heinzel, A.; Schulz, C.; Wiggers, H.

    2012-10-01

    Olivine, LiFePO4 is a promising cathode material for lithium-ion batteries due to its low cost, environmental acceptability and high stability. Its low electric conductivity prevented it for a long time from being used in large-scale applications. Decreasing its particle size along with carbon coating significantly improves electronic conductivity and lithium diffusion. With respect to the controlled formation of very small particles with large specific surface, gas-phase synthesis opens an economic and flexible route towards high-quality battery materials. Amorphous FePO4 was synthesized as precursor material for LiFePO4 by flame spray pyrolysis of a solution of iron acetylacetonate and tributyl phosphate in toluene. The pristine FePO4 with a specific surface from 126-218 m2 g-1 was post-processed to LiFePO4/C composite material via a solid-state reaction using Li2CO3 and glucose. The final olivine LiFePO4/C particles still showed a large specific surface of 24 m2 g-1 and were characterized using X-ray diffraction (XRD), electron microscopy, X-ray photoelectron spectrocopy (XPS) and elemental analysis. Electrochemical investigations of the final LiFePO4/C composites show reversible capacities of more than 145 mAh g-1 (about 115 mAh g-1 with respect to the total coating mass). The material supports high drain rates at 16 C while delivering 40 mAh g-1 and causes excellent cycle stability.

  5. Preparation, characterization and properties of ZnO nanomaterials

    NASA Astrophysics Data System (ADS)

    Luo, Jiaolian; Zhang, Xiaoming; Chen, Ruxue; Wang, Xiaohui; Zhu, Ji; Wang, Xiaomin

    2017-06-01

    In this paper, using the hydrothermal synthesis method, NaOH, Zn(NO3)2, anhydrous ethanol, deionized water as raw material to prepare ZnO nanomaterial, and by X ray diffraction (XRD), scanning electron microscopy (SEM) and photoluminescence spectroscopy (PL) on the synthesis of nano materials, surface morphology and phase luminescence characterization. The results show that the nano materials synthesized for single-phase ZnO, belonging to the six wurtzite structure; material surface shaped, arranged evenly distributed, and were the top six party structure; ZnO nano materials synthesized with strong emission spectra, emission peak is located at 394nm.

  6. Influence of aspect ratio and surface defect density on hydrothermally grown ZnO nanorods towards amperometric glucose biosensing applications

    NASA Astrophysics Data System (ADS)

    Shukla, Mayoorika; Pramila; Dixit, Tejendra; Prakash, Rajiv; Palani, I. A.; Singh, Vipul

    2017-11-01

    In this work, hydrothermally grown ZnO Nanorods Array (ZNA) has been synthesized over Platinum (Pt) coated glass substrate, for biosensing applications. In-situ addition of strong oxidizing agent viz KMnO4 during hydrothermal growth was found to have profound effect on the physical properties of ZNA. Glucose oxidase (GOx) was later immobilized over ZNA by means of physical adsorption process. Further influence of varying aspect ratio, enzyme loading and surface defects on amperometric glucose biosensor has been analyzed. Significant variation in biosensor performance was observed by varying the amount of KMnO4 addition during the growth. Moreover, investigations revealed that the suppression of surface defects and aspect ratio variation of the ZNA played key role towards the observed improvement in the biosensor performance, thereby significantly affecting the sensitivity and response time of the fabricated biosensor. Among different biosensors fabricated having varied aspect ratio and surface defect density of ZNA, the best electrode resulted into sensitivity and response time to be 18.7 mA cm-2 M-1 and <5 s respectively. The observed results revealed that apart from high aspect ratio nanostructures and the extent of enzyme loading, surface defect density also hold a key towards ZnO nanostructures based bio-sensing applications.

  7. Hierarchically Self-Assembled Star-Shaped ZnO Microparticles for Electrochemical Sensing of Amines.

    PubMed

    Du, Jianping; Huang, Xiaoxi; Zhao, Ruihua; Li, Jinping; Asefa, Tewodros

    2016-06-06

    Novel, hierarchically nanostructured, star-shaped ZnO (SSZ) microparticles are synthesized by a hydrothermal synthetic route. The SSZ microparticles serve as effective platforms for electrochemical detection of amines in solution. The morphology and structure of the materials are characterized by X-ray diffraction, scanning electron microscopy, transmission electron microscopy, Raman spectroscopy, and UV/Vis spectroscopy. The as-synthesized SSZ microparticles comprise self-assembled hexagonal prisms that possess nanometer and micrometer pores in their structure and on their surfaces-structural features that are conducive to sensing applications. An electrode fabricated by using the hierarchically nanostructured SSZ materials serve as a sensitive electrochemical sensor for detection of low concentrations of ethylenediamine, with a sensitivity of 2.98×10(-2)  mA cm(-2)  mm(-1) , a detection limit of 2.36×10(-2)  mm, and a short response time of 8 s. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  8. In-vitro antibacterial study of zinc oxide nanostructures on Streptococcus sobrinus

    NASA Astrophysics Data System (ADS)

    Bakhori, Siti Khadijah Mohd; Mahmud, Shahrom; Ann, Ling Chuo; Sirelkhatim, Amna; Hasan, Habsah; Mohamad, Dasmawati; Masudi, Sam'an Malik; Seeni, Azman; Rahman, Rosliza Abd

    2014-10-01

    Zinc oxide nanostructures were prepared using a pilot plant of zinc oxide boiling furnace. Generally, it produced two types of nanostructures different in morphology; one is rod-like shaped (ZnO-1) and a plate-like shape (ZnO-2). The properties of ZnO were studied by structural, optical and morphological using XRD, PL and FESEM respectively. The XRD patterns confirmed the wurtzite structures of ZnO with the calculated crystallite size of 41 nm (ZnO-1) and 42 nm (ZnO-2) using Scherrer formula. The NBE peaks were determined by photoluminescence spectra which reveal peak at 3.25 eV and 3.23 eV for ZnO-1 and ZnO-2 respectively. Prior to that, the morphologies for both ZnO-1 and ZnO-2 were demonstrated from FESEM micrographs. Subsequently the antibacterial study was conducted using in-vitro broth dilution technique towards a gram positive bacterium Streptococcus sobrinus (ATCC 33478) to investigate the level of antibacterial effect of zinc oxide nanostructures as antibacterial agent. Gradual increment of ZnO concentrations from 10-20 mM affected the inhibition level after twenty four hours of incubation. In conjunction with concentration increment of ZnO, the percentage inhibition towards Streptococcus sobrinus was also increased accordingly. The highest inhibition occurred at 20 mM of ZnO-1 and ZnO-2 for 98% and 77% respectively. It showed that ZnO has good properties as antibacterial agent and relevancy with data presented by XRD, PL and FESEM were determined.

  9. Influence of the ZnO nanoarchitecture on the electrochemical performances of binder-free anodes for Li storage

    SciTech Connect

    Dall'Asta, V.; Tealdi, C.; Resmini, A.

    Zinc oxide nanoarchitectures may be employed as binder-free, high specific capacity anodes for lithium batteries. By means of simple and low-impact wet chemistry approaches, we synthesized 1D (nanorods), 2D (single- and multi-layered nanosheets), and 3D (nanobrushes) ZnO arrays. These nanoarchitectures were compared as far as concerns their electrochemical properties and the structural modifications upon lithiation/delithiation. The best results were offered by 2D nanosheets, which showed reversible capacity of the order of 400 mAhg{sup −1} after 100 cycles at 1 Ag{sup −1}. This was due to: i) small nanoparticles, with average diameter of about 10 nm, which maximize the array specificmore » surface area and favor the formation of the LiZn alloy; ii) the presence of a mesoporous texture, which allows larger space for accommodating the volume changes upon lithiation/delithiation. However, also these 2D structures showed large irreversible capacity losses. Our work highlights the need for more efficient buffering solutions in ZnO binder-free nanostructured anodes. - Graphical abstract: ZnO nanosheets as anode materials for lithium batteries.« less

  10. The shift of optical band gap in W-doped ZnO with oxygen pressure and doping level

    SciTech Connect

    Chu, J.; Chongqing Institute of Green and Intelligent Technology, Chinese Academy of Science, Chongqing 400714; Peng, X.Y.

    2014-06-01

    Highlights: • CVD–PLD co-deposition technique was used. • Better crystalline of the ZnO samples causes the redshift of the optical band gap. • Higher W concentration induces blueshift of the optical band gap. - Abstract: Tungsten-doped (W-doped) zinc oxide (ZnO) nanostructures were synthesized on quartz substrates by pulsed laser and hot filament chemical vapor co-deposition technique under different oxygen pressures and doping levels. We studied in detail the morphological, structural and optical properties of W-doped ZnO by SEM, XPS, Raman scattering, and optical transmission spectra. A close correlation among the oxygen pressure, morphology, W concentrations and the variation of bandmore » gaps were investigated. XPS and Raman measurements show that the sample grown under the oxygen pressure of 2.7 Pa has the maximum tungsten concentration and best crystalline structure, which induces the redshift of the optical band gap. The effect of W concentration on the change of morphology and shift of optical band gap was also studied for the samples grown under the fixed oxygen pressure of 2.7 Pa.« less

  11. Reduced graphene Oxide/ZnO nanostructures based rectifier diode

    NASA Astrophysics Data System (ADS)

    Bhatnagar, Sameeksha; Kumar, Ravi; Sharma, Monika; Kuanr, Bijoy K.

    2017-05-01

    We report on the fabrication and characterization of graphene oxide and reduced graphene oxide/ZnO nanostructures on ITO-coated glass substrates for the rectification properties of a heterojunction device. The composites of GO/ZnO and rGO/ZnO were synthesized by the modified Hummers method followed by annealing process in N2 and H2 ambient atmosphere at various temperatures. The structural and compositional analysis of the composite material have been investigated using X-ray diffraction spectroscopy and Raman spectroscopy. The optical properties of the composite films were studied by UV-visible spectroscopy and the band-gap was obtained by Tauc's plot. The band-gap reduces to 2.4 eV for the composite film as compared to ZnO film 3.26 eV. The I-V characteristics of ZnO thin films and rGO/ZnO films were done for different light conditions viz dark, ambient light and UV-illumination. It has been observed that the threshold voltage decreases when the sample was placed in UV-illumination. A direct variation in photo-response is revealed with the bias voltage as well as UV illumination. The fabricated device could be used as an Ultraviolet Photo-detector.

  12. Nucleant layer effect on nanocolumnar ZnO films grown by electrodeposition

    NASA Astrophysics Data System (ADS)

    Tolosa, Maria D. Reyes; Damonte, Laura C.; Brine, Hicham; Bolink, Henk J.; Hernández-Fenollosa, María A.

    2013-03-01

    Different ZnO nanostructured films were electrochemically grown, using an aqueous solution based on ZnCl2, on three types of transparent conductive oxides grow on commercial ITO (In2O3:Sn)-covered glass substrates: (1) ZnO prepared by spin coating, (2) ZnO prepared by direct current magnetron sputtering, and (3) commercial ITO-covered glass substrates. Although thin, these primary oxide layers play an important role on the properties of the nanostructured films grown on top of them. Additionally, these primary oxide layers prevent direct hole combination when used in optoelectronic devices. Structural and optical characterizations were carried out by scanning electron microscopy, atomic force microscopy, and optical transmission spectroscopy. We show that the properties of the ZnO nanostructured films depend strongly on the type of primary oxide-covered substrate used. Previous studies on different electrodeposition methods for nucleation and growth are considered in the final discussion.

  13. Nucleant layer effect on nanocolumnar ZnO films grown by electrodeposition.

    PubMed

    Tolosa, Maria D Reyes; Damonte, Laura C; Brine, Hicham; Bolink, Henk J; Hernández-Fenollosa, María A

    2013-03-23

    Different ZnO nanostructured films were electrochemically grown, using an aqueous solution based on ZnCl2, on three types of transparent conductive oxides grow on commercial ITO (In2O3:Sn)-covered glass substrates: (1) ZnO prepared by spin coating, (2) ZnO prepared by direct current magnetron sputtering, and (3) commercial ITO-covered glass substrates. Although thin, these primary oxide layers play an important role on the properties of the nanostructured films grown on top of them. Additionally, these primary oxide layers prevent direct hole combination when used in optoelectronic devices. Structural and optical characterizations were carried out by scanning electron microscopy, atomic force microscopy, and optical transmission spectroscopy. We show that the properties of the ZnO nanostructured films depend strongly on the type of primary oxide-covered substrate used. Previous studies on different electrodeposition methods for nucleation and growth are considered in the final discussion.

  14. Nucleant layer effect on nanocolumnar ZnO films grown by electrodeposition

    PubMed Central

    2013-01-01

    Different ZnO nanostructured films were electrochemically grown, using an aqueous solution based on ZnCl2, on three types of transparent conductive oxides grow on commercial ITO (In2O3:Sn)-covered glass substrates: (1) ZnO prepared by spin coating, (2) ZnO prepared by direct current magnetron sputtering, and (3) commercial ITO-covered glass substrates. Although thin, these primary oxide layers play an important role on the properties of the nanostructured films grown on top of them. Additionally, these primary oxide layers prevent direct hole combination when used in optoelectronic devices. Structural and optical characterizations were carried out by scanning electron microscopy, atomic force microscopy, and optical transmission spectroscopy. We show that the properties of the ZnO nanostructured films depend strongly on the type of primary oxide-covered substrate used. Previous studies on different electrodeposition methods for nucleation and growth are considered in the final discussion. PMID:23522332

  15. Luminescence dynamics of bound exciton of hydrogen doped ZnO nanowires

    DOE PAGES

    Yoo, Jinkyoung; Yi, Gyu -Chul; Chon, Bonghwan; ...

    2016-04-11

    In this study, all-optical camera, converting X-rays into visible photons, is a promising strategy for high-performance X-ray imaging detector requiring high detection efficiency and ultrafast detector response time. Zinc oxide is a suitable material for all-optical camera due to its fast radiative recombination lifetime in sub-nanosecond regime and its radiation hardness. ZnO nanostructures have been considered as proper building blocks for ultrafast detectors with spatial resolution in sub-micrometer scale. To achieve remarkable enhancement of luminescence efficiency n-type doping in ZnO has been employed. However, luminescence dynamics of doped ZnO nanostructures have not been thoroughly investigated whereas undoped ZnO nanostructures havemore » been employed to study their luminescence dynamics. Here we report a study of luminescence dynamics of hydrogen doped ZnO nanowires obtained by hydrogen plasma treatment. Hydrogen doping in ZnO nanowires gives rise to significant increase in the near-band-edge emission of ZnO and decrease in averaged photoluminescence lifetime from 300 to 140 ps at 10 K. The effects of hydrogen doping on the luminescent characteristics of ZnO nanowires were changed by hydrogen doping process variables.« less

  16. Gd{sup 3+} incorporated ZnO nanoparticles: A versatile material

    SciTech Connect

    Kumar, Surender, E-mail: surender40@gmail.com; Sahare, P.D.

    Graphical abstract: - Highlights: • Chemically synthesized Gd{sup 3+} doped ZnO nanoparticles. • The broad visible emission of the ZnO is dependent on the surface defects and can be tailored by Gd{sup 3+} doing. • PL and magnetic properties are modified by Gd{sup 3+} doping. • Photocatalysis experiment reveals that the ZnO: Gd{sup 3+} degrades the Rh B dye faster than the undoped ZnO. - Abstract: Gd{sup 3+} doped ZnO nanoparticles are synthesized by wet chemical route method and investigated through structural, optical, magnetic and photocatalytic properties. Transmission Electron Microscopy technique has been performed on undoped and Gd{sup 3+} dopedmore » ZnO nanoparticles. X-ray diffraction, X-ray photoelectron spectroscopy and Raman analyses are carried out in order to examine the desired phase formation and substitution of Gd{sup 3+} in the ZnO matrix. Gd{sup 3+} doped ZnO nanoparticles show enhanced photoluminescent and ferromagnetic properties as compared to undoped ZnO. The broad visible emission of ZnO is found to be largely dependent on the surface defects and these surface defects can be tailored by Gd{sup 3+} doping concentration. Furthermore, Gd{sup 3+} doped ZnO nanoparticles also show improved photocatalytic properties as compared with undoped ZnO nanoparticles under ultraviolet irradiation.« less

  17. ZnO based potentiometric and amperometric nanosensors.

    PubMed

    Willander, Magnus; Khun, Kimleang; Ibupoto, Zafar Hussain

    2014-09-01

    The existence of nanomaterials provides the solid platform for sensing applications due to owing of high sensitivity and a low concentration limit of detection. More likely used nanomaterials for sensing applications includes gold nanoparticles, carbon nanotubes, magnetic nanoparticles such as Fe3O4, quantum dots and metal oxides etc. Recently nanomaterial and biological detection becomes an interdisciplinary field and is very much focussed by the researchers. Among metal oxides ZnO is largely considered due to its less toxic nature, biocompatible, cheap and easy to synthesis. ZnO nanomaterial is highly used for the chemical sensing, especially electrochemical sensing due to its fascinating properties such as high surface to volume ratio, atoxic, biosafe and biocompatible. Moreover, ZnO nanostructures exhibit unique features which could expose a suitable nanoenviroment for the immobilization of proteineous material such as enzymes, DNA, antibodies, etc. and in doing so it retains the biological efficiency of the immobilized bio sensitive material. The following review describes the two different coatings (i.e., ionophore and enzyme) on the surface of ZnO nanorods for the chemical sensing of zinc ion detection, thallium (I) ion detection, and L-lactic acid and the measurement of galactose molecules. ZnO nanorods provide the excellent transducing properties in the generation of strong electrical signals. Moreover, this review is very much focused on the applications of ZnO nanostructures in the sensing field.

  18. Synthesis, characterization and photocatalysis enhancement of Eu2O3-ZnO mixed oxide nanoparticles

    NASA Astrophysics Data System (ADS)

    Mohamed, W. S.; Abu-Dief, Ahmed M.

    2018-05-01

    Pure ZnO nanoparticles (NPs) and mixed Eu2O3 and ZnO NPs with different Eu2O3 ratios (5%, 10%, and 15%) were synthesized by a precipitation method under optimum conditions. The synthesized samples were characterized by means of X-ray diffraction, scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy, transmission electron microscopy (TEM), Fourier transform infrared (FTIR) spectroscopy, Raman spectroscopy, and UV-vis diffuse reflectance spectroscopy. The as-synthesized ZnO NPs exhibit high phase purity and a highly crystalline wurtzite ZnO structure. The mixed Eu2O3 and ZnO NPs exhibit a Eu2O3 zinc blend phase in addition to the wurtzite phase of pure ZnO, confirming the high purity and good crystallinity of the as-synthesized samples. The high-purity formation of ZnO and Eu2O3 phases was confirmed by FTIR and Raman spectra. Microstructural analysis by SEM and TEM confirmed the sphere-like morphology with different particle sizes (29-40 nm) of the as-synthesized samples. The photocatalytic activities of pure ZnO NPs and mixed Eu2O3 and ZnO NPs for the degradation of methylene blue were evaluated under ultraviolet (UV) irradiation. The results show that Eu2O3 plays an important role in the enhancement of the photocatalytic properties of ZnO NPs. We found that mixed 5% Eu2O3 and ZnO NPs exhibit the highest photocatalytic activity (degradation efficiency of 96.5% after 180 min of UV irradiation) as compared with pure ZnO NPs (degradation efficiency of 80.3% after 180 min of UV irradiation). The increased photocatalytic activity of the optimum mixed Eu2O3 and ZnO NPs is due to the high crystallinity, high surface area with small particle size, and narrow energy gap.

  19. Microwave synthesis and photocatalytic activities of ZnO bipods with different aspect ratios

    SciTech Connect

    Sun, Fazhe; Zhao, Zengdian; Qiao, Xueliang, E-mail: xuelqiao@163.com

    2016-02-15

    Highlights: • We synthesized linked ZnO nanorods by a facile microwave method. • The effect of reaction parameters on ZnO was investigated. • ZnO bipods with different aspect ratios were prepared. • The photocatalytic performance of ZnO bipods was evaluated. - Abstract: Linked ZnO nanorods have been successfully prepared via a facile microwave method without any post-synthesis treatment. The X-ray diffraction (XRD) patterns indicated the precursor had completely transformed into the pure ZnO crystal. The images of field emitting scanning electron microscope (FESEM) and transmission electron microscope (TEM) showed that linked ZnO nanorods consisted predominantly of ZnO bipods. The formationmore » process of the ZnO bipods was clearly discussed. ZnO bipods with different aspect ratios have been obtained by tuning the concentrations of reagents and microwave power. Moreover, the photocatalytic performance of ZnO bipods with different aspect ratios for degradation of methylene blue was systematically evaluated. The results of photocatalytic experiments showed that the photocatalytic activity increased with the aspect ratios of ZnO bipods increased. The reason is that ZnO bipods with larger aspect ratio have higher surface area, which can absorb more MB molecules to react with ·OH radicals.« less

  20. Chemical manipulation of oxygen vacancy and antibacterial activity in ZnO.

    PubMed

    V, Lakshmi Prasanna; Vijayaraghavan, Rajagopalan

    2017-08-01

    Pure and doped ZnO (cation and anion doping) compositions have been designed in order to manipulate oxygen vacancy and antibacterial activity of ZnO. In this connection, we have synthesized and characterized micron sized ZnO, N doped micron sized ZnO, nano ZnO, nano Na and La doped ZnO. The intrinsic vacancies in pure ZnO and the vacancies created by N and Na doping in ZnO have been confirmed by X-ray Photoelectron Spectroscopy(XPS) and Photoluminiscence Spectroscopy(PL). Reactive oxygen species (ROS) such as hydroxyl radicals, superoxide radicals and H 2 O 2 responsible for antibacterial activity have been estimated by PL, UV-Vis spectroscopy and KMnO 4 titrations respectively. It was found that nano Na doped ZnO releases highest amount of ROS followed by nano ZnO, micron N doped ZnO while micron ZnO releases the least amount of ROS. The concentration of vacancies follows the same sequence. This illustrates directly the correlation between ROS and oxygen vacancy in well designed pure and doped ZnO. For the first time, material design in terms of cation doping and anion doping to tune oxygen vacancies has been carried out. Interaction energy (E g ), between the bacteria and nanoparticles has been calculated based on Extended Derjaguin-Landau-Verwey-Overbeek (EDLVO) theory and is correlated with antibacterial activity. Copyright © 2017 Elsevier B.V. All rights reserved.

  1. Porous Core-Shell Nanostructures for Catalytic Applications

    NASA Astrophysics Data System (ADS)

    Ewers, Trevor David

    Porous core-shell nanostructures have recently received much attention for their enhanced thermal stability. They show great potential in the field of catalysis, as reactant gases can diffuse in and out of the porous shell while the core particle is protected from sintering, a process in which particles coalesce to form larger particles. Sintering is a large problem in industry and is the primary cause of irreversible deactivation. Despite the obvious advantages of high thermal stability, porous core-shell nanoparticles can be developed to have additional interactive properties from the combination of the core and shell together, rather than just the core particle alone. This dissertation focuses on developing new porous core-shell systems in which both the core and shell take part in catalysis. Two types of systems are explored; (1) yolk-shell nanostructures with reducible oxide shells formed using the Kirkendall effect and (2) ceramic-based porous oxide shells formed using sol-gel chemistry. Of the Kirkendall-based systems, Au FexOy and Cu CoO were synthesized and studied for catalytic applications. Additionally, ZnO was explored as a potential shelling material. Sol-gel work focused on optimizing synthetic methods to allow for coating of small gold particles, which remains a challenge today. Mixed metal oxides were explored as a shelling material to make dual catalysts in which the product of a reaction on the core particle becomes a reactant within the shell.

  2. Effect of immobilization technique on performance ZnO nanorods based enzymatic electrochemical glucose biosensor

    NASA Astrophysics Data System (ADS)

    Shukla, Mayoorika; Pramila; Palani, I. A.; Singh, Vipul

    2017-11-01

    In this paper, ZnO Nanorods (ZNR) have been synthesized over Platinum (Pt) coated glass substrate with in-situ addition KMnO4 during hydrothermal growth process. Significant variation in ZnO nanostructures was observed by KMnO4 addition during the growth. Glucose oxidase was later immobilized over ZNRs. The as-prepared ZNRs were further utilized for glucose detection by employing amperometric electrochemical transduction method. In order to optimize the performance of the prepared biosensor two different immobilization techniques i.e. physical adsorption and cross linking have been employed and compared. Further investigations suggest that immobilization via cross linking method resulted in the improvement of the biosensor performance, thereby significantly affecting the sensitivity and linear range of the fabricated biosensor. Among the two types of biosensors fabricated using ZNR, the best performance was shown by cross linked electrodes. The sensitivity for the same was found to be 17.7 mA-cm-2-M-1, along with a wide linear range of 0.5-8.5 mM.

  3. Defect-induced ferromagnetism in ZnO nanoparticles prepared by mechanical milling

    NASA Astrophysics Data System (ADS)

    Phan, The-Long; Zhang, Y. D.; Yang, D. S.; Nghia, N. X.; Thanh, T. D.; Yu, S. C.

    2013-02-01

    Though ZnO is known as a diamagnetic material, recent studies have revealed that its nanostructures can be ferromagnetic (FM). The FM origin has been ascribed to intrinsic defects. This work shines light on an alternate method based on mechanical milling to induce defect-related ferromagnetism in ZnO nanoparticles (NPs) from initial diamagnetic ZnO powders. Our idea is motivated by the fact that mechanical milling introduces more defects to a ground material. We point out that the FM order increases with increasing the density of defects in ZnO NPs. The experimental results obtained from analyzing X-ray absorption, electron spin resonance, and Raman scattering spectra demonstrate that the ferromagnetism in ZnO NPs is due to intrinsic defects mainly related to oxygen and zinc vacancies. Among these, zinc vacancies play a decisive role in introducing a high FM order in ZnO NPs.

  4. Natural Biowaste-Cocoon-Derived Granular Activated Carbon-Coated ZnO Nanorods: A Simple Route To Synthesizing a Core-Shell Structure and Its Highly Enhanced UV and Hydrogen Sensing Properties.

    PubMed

    Saravanan, Adhimoorthy; Huang, Bohr-Ran; Kathiravan, Deepa; Prasannan, Adhimoorthy

    2017-11-15

    Granular activated carbon (GAC) materials were prepared via simple gas activation of silkworm cocoons and were coated on ZnO nanorods (ZNRs) by the facile hydrothermal method. The present combination of GAC and ZNRs shows a core-shell structure (where the GAC is coated on the surface of ZNRs) and is exposed by systematic material analysis. The as-prepared samples were then fabricated as dual-functional sensors and, most fascinatingly, the as-fabricated core-shell structure exhibits better UV and H 2 sensing properties than those of as-fabricated ZNRs and GAC. Thus, the present core-shell structure-based H 2 sensor exhibits fast responses of 11% (10 ppm) and 23.2% (200 ppm) with ultrafast response and recovery. However, the UV sensor offers an ultrahigh photoresponsivity of 57.9 A W -1 , which is superior to that of as-grown ZNRs (0.6 A W -1 ). Besides this, switching photoresponse of GAC/ZNR core-shell structures exhibits a higher switching ratio (between dark and photocurrent) of 1585, with ultrafast response and recovery, than that of as-grown ZNRs (40). Because of the fast adsorption ability of GAC, it was observed that the finest distribution of GAC on ZNRs results in rapid electron transportation between the conduction bands of GAC and ZNRs while sensing H 2 and UV. Furthermore, the present core-shell structure-based UV and H 2 sensors also well-retained excellent sensitivity, repeatability, and long-term stability. Thus, the salient feature of this combination is that it provides a dual-functional sensor with biowaste cocoon and ZnO, which is ecological and inexpensive.

  5. Enhanced antibacterial activity of zinc oxide nanoparticles synthesized using Petroselinum crispum extracts

    NASA Astrophysics Data System (ADS)

    Stan, Manuela; Popa, Adriana; Toloman, Dana; Silipas, Teofil-Danut; Vodnar, Dan Cristian; Katona, Gabriel

    2015-12-01

    The present contribution reports the synthesis of zinc oxide nanoparticles (ZnO NPs) using aqueous leaf and root extracts of Petroselinum crispum (parsley) and characterization of as-prepared samples. ZnO NPs are subjected to X-ray diffraction (XRD), transmission electron microscopy (TEM) and electron paramagnetic resonance (EPR) studies. The XRD studies reveal a hexagonal wurtzite structure without supplementary diffraction lines for all ZnO samples. TEM analysis shows that the particle size is influenced by the type of plant extract. The EPR spectra indicate the presence of Mn2+ ions in ZnO sample synthesized using P. crispum leaf extract, while zinc vacancy complexes and oxygen vacancies are evidenced in all analyzed samples. ZnO NPs synthesized using P. crispum extracts exhibit increased (2-16 times) antibacterial activity as compared to chemically synthesized ZnO NPs.

  6. Enhanced antibacterial activity of zinc oxide nanoparticles synthesized using Petroselinum crispum extracts

    SciTech Connect

    Stan, Manuela, E-mail: manuela.stan@itim-cj.ro; Popa, Adriana; Toloman, Dana

    The present contribution reports the synthesis of zinc oxide nanoparticles (ZnO NPs) using aqueous leaf and root extracts of Petroselinum crispum (parsley) and characterization of as-prepared samples. ZnO NPs are subjected to X-ray diffraction (XRD), transmission electron microscopy (TEM) and electron paramagnetic resonance (EPR) studies. The XRD studies reveal a hexagonal wurtzite structure without supplementary diffraction lines for all ZnO samples. TEM analysis shows that the particle size is influenced by the type of plant extract. The EPR spectra indicate the presence of Mn{sup 2+} ions in ZnO sample synthesized using P. crispum leaf extract, while zinc vacancy complexes andmore » oxygen vacancies are evidenced in all analyzed samples. ZnO NPs synthesized using P. crispum extracts exhibit increased (2-16 times) antibacterial activity as compared to chemically synthesized ZnO NPs.« less

  7. Morphologically manipulated Ag/ZnO nanostructures as surface enhanced Raman scattering probes for explosives detection

    NASA Astrophysics Data System (ADS)

    Shaik, Ummar Pasha; Hamad, Syed; Ahamad Mohiddon, Md.; Soma, Venugopal Rao; Ghanashyam Krishna, M.

    2016-03-01

    The detection of secondary explosive molecules (e.g., ANTA, FOX-7, and CL-20) using Ag decorated ZnO nanostructures as surface enhanced Raman scattering (SERS) probes is demonstrated. ZnO nanostructures were grown on borosilicate glass substrates by rapid thermal oxidation of metallic Zn films at 500 °C. The oxide nanostructures, including nanosheets and nanowires, emerged over the surface of the Zn film leaving behind the metal residue. We demonstrate that SERS measurements with concentrations as low as 10 μM, of the three explosive molecules ANTA, FOX-7, and CL-20 over ZnO/Ag nanostructures, resulted in enhancement factors of ˜107, ˜107, and ˜104, respectively. These measurements validate the high sensitivity of detection of explosive molecules using Ag decorated ZnO nanostructures as SERS substrates. The Zn metal residue and conditions of annealing play an important role in determining the detection sensitivity.

  8. Vertically aligned ZnO nanorod core-polypyrrole conducting polymer sheath and nanotube arrays for electrochemical supercapacitor energy storage

    PubMed Central

    2014-01-01

    Nanocomposite electrodes having three-dimensional (3-D) nanoscale architecture comprising of vertically aligned ZnO nanorod array core-polypyrrole (PPy) conducting polymer sheath and the vertical PPy nanotube arrays have been investigated for supercapacitor energy storage. The electrodes in the ZnO nanorod core-PPy sheath structure are formed by preferential nucleation and deposition of PPy layer over hydrothermally synthesized vertical ZnO nanorod array by controlled pulsed current electropolymerization of pyrrole monomer under surfactant action. The vertical PPy nanotube arrays of different tube diameter are created by selective etching of the ZnO nanorod core in ammonia solution for different periods. Cyclic voltammetry studies show high areal-specific capacitance approximately 240 mF.cm-2 for open pore and approximately 180 mF.cm-2 for narrow 30-to-36-nm diameter PPy nanotube arrays attributed to intensive faradic processes arising from enhanced access of electrolyte ions through nanotube interior and exterior. Impedance spectroscopy studies show that capacitive response extends over larger frequency domain in electrodes with PPy nanotube structure. Simulation of Nyquist plots by electrical equivalent circuit modeling establishes that 3-D nanostructure is better represented by constant phase element which accounts for the inhomogeneous electrochemical redox processes. Charge-discharge studies at different current densities establish that kinetics of the redox process in PPy nanotube electrode is due to the limitation on electron transport rather than the diffusive process of electrolyte ions. The PPy nanotube electrodes show deep discharge capability with high coulomb efficiency and long-term charge-discharge cyclic studies show nondegrading performance of the specific areal capacitance tested for 5,000 cycles. PMID:25246867

  9. Contrasting emission behaviour of phenanthroimidazole with ZnO nanoparticles.

    PubMed

    Karunakaran, C; Jayabharathi, J; Sathishkumar, R; Jayamoorthy, K; Vimal, K

    2013-11-01

    A new fluorophore 2-(4-fluorophenyl)-1-phenyl-1H-phenanthro [9,10-d]imidazole has been synthesized and characterized by spectroscopic techniques. Nanoparticulate ZnO enhances the fluorescence of the synthesised fluorophore. The absorption, fluorescence, lifetime, cyclic voltammetry and infrared studies reveal that fluorophore is attached to the surface of ZnO semiconductor. Photo-induced electron transfer (PET) explains the enhancement of fluorescence by nanoparticulate ZnO and the apparent binding constant has been obtained. Adsorption of the fluorophore on ZnO nanoparticle lowers the HOMO and LUMO energy levels of the fluorophore. The strong adsorption of the phenanthrimidazole derivative on the surface of ZnO nanocrystals is likely due to the chemical affinity of the nitrogen atom of the organic molecule to the zinc ion on the surface of nanocrystal. Copyright © 2013 Elsevier B.V. All rights reserved.

  10. Fabrication and Performance Study on Individual Zno Nanowires Based Bioelectrode

    NASA Astrophysics Data System (ADS)

    Zhao, Yanguang; Yan, Xiaoqin; Kang, Zhuo; Lin, Pei

    2012-08-01

    One-dimensional zinc oxide nanowires (ZnO NWs) have unique advantages for use in biosensors as follows: oxide stable surface, excellent biosafety, high specific surface area, high isoelectric point (IEP = 9.5). In this work, we have prepared a kind of electrochemical bioelectrode based on individual ZnO NWs. Here, ZnO NWs with high quality were successfully synthesized by CVD method, which were characterized by scanning electron microscopy, X-ray diffraction and photoluminescence. Then the Raman spectra and electrical characterization demonstrated the adsorption of uricase on ZnO wires. At last, a series of electrochemical measurements were carried out by using an electrochemical workstation with a conventional three-electrode system to obtain the cyclic voltammetry characteristics of the bioelectrodes. The excellent performance of the fabricated bioelectrode implies the potential application for single ZnO nanowire to construct electrochemical biosensor for the detection of uric acid.

  11. CoFe2O4-TiO2 and CoFe2O4-ZnO thin film nanostructures elaborated from colloidal chemistry and atomic layer deposition.

    PubMed

    Clavel, Guylhaine; Marichy, Catherine; Willinger, Marc-Georg; Ravaine, Serge; Zitoun, David; Pinna, Nicola

    2010-12-07

    CoFe(2)O(4)-TiO(2) and CoFe(2)O(4)-ZnO nanoparticles/film composites were prepared from directed assembly of colloidal CoFe(2)O(4) in a Langmuir-Blodgett monolayer and atomic layer deposition (ALD) of an oxide (TiO(2) or ZnO). The combination of these two methods permits the use of well-defined nanoparticles from colloidal chemistry, their assembly on a large scale, and the control over the interface between a ferrimagnetic material (CoFe(2)O(4)) and a semiconductor (TiO(2) or ZnO). Using this approach, architectures can be assembled with a precise control from the Angstrom scale (ALD) to the micrometer scale (Langmuir-Blodgett film). The resulting heterostructures present well-calibrated thicknesses. Electron microscopy and magnetic measurement studies give evidence that the size of the nanoparticles and their intrinsic magnetic properties are not altered by the various steps involved in the synthesis process. Therefore, the approach is suitable to obtain a layered composite with a quasi-monodisperse layer of ferrimagnetic nanoparticles embedded in an ultrathin film of semiconducting material.

  12. Periodic nanostructural materials for nanoplasmonics

    NASA Astrophysics Data System (ADS)

    Choi, Dukhyun

    2017-02-01

    Nanoscale periodic material design and fabrication are essentially fundamental requirement for basic scientific researches and industrial applications of nanoscience and engineering. Innovative, effective, reproducible, large-area uniform, tunable and robust nanostructure/material syntheses are still challenging. Here, I would like to introduce the novel periodic nanostructural materials particularly with uniformly ordered nanoporous or nanoflower structures, which are fabricated by simple, cost-effective, and high-throughput wet chemical methods. I also report large-area periodic plasmonic nanostructures based on template-based nanolithography. The surface morphology and optical properties are characterized by SEM and UV-vis. spectroscopy. Furthermore, their enhancement factor is evaluated by using SERS signals.

  13. Growth of catalyst-free high-quality ZnO nanowires by thermal evaporation under air ambient

    PubMed Central

    2012-01-01

    ZnO nanowires have been successfully fabricated on Si substrate by simple thermal evaporation of Zn powder under air ambient without any catalyst. Morphology and structure analyses indicated that ZnO nanowires had high purity and perfect crystallinity. The diameter of ZnO nanowires was 40 to 100 nm, and the length was about several tens of micrometers. The prepared ZnO nanowires exhibited a hexagonal wurtzite crystal structure. The growth of the ZnO nanostructure was explained by the vapor-solid mechanism. The simplicity, low cost and fewer necessary apparatuses of the process would suit the high-throughput fabrication of ZnO nanowires. The ZnO nanowires fabricated on Si substrate are compatible with state-of-the-art semiconductor industry. They are expected to have potential applications in functional nanodevices. PMID:22502639

  14. Aqueous chemical growth of free standing vertical ZnO nanoprisms, nanorods and nanodiskettes with improved texture co-efficient and tunable size uniformity

    NASA Astrophysics Data System (ADS)

    Ram, S. D. Gopal; Ravi, G.; Athimoolam, A.; Mahalingam, T.; Kulandainathan, M. Anbu

    2011-12-01

    Tuning the morphology, size and aspect ratio of free standing ZnO nanostructured arrays by a simple hydrothermal method is reported. Pre-coated ZnO seed layers of two different thicknesses (≈350 nm or 550 nm) were used as substrates to grow ZnO nanostructures for the study. Various parameters such as chemical ambience, pH of the solution, strength of the Zn2+ atoms and thickness of seed bed are varied to analyze their effects on the resultant ZnO nanostructures. Vertically oriented hexagonal nanorods, multi-angular nanorods, hexagonal diskette and popcorn-like nanostructures are obtained by altering the experimental parameters. All the produced nanostructures were analysed by X-ray powder diffraction analysis and found to be grown in the (002) orientation of wurtzite ZnO. The texture co-efficient of ZnO layer was improved by combining a thick seed layer with higher cationic strength. Surface morphological studies reveal various nanostructures such as nanorods, diskettes and popcorn-like structures based on various preparation conditions. The optical property of the closest packed nanorods array was recorded by UV-VIS spectrometry, and the band gap value simulated from the results reflect the near characteristic band gap of ZnO. The surface roughness profile taken from the Atomic Force Microscopy reveals a roughness of less than 320 nm.

  15. Trioctylphosphine-assisted morphology control of ZnO nanoparticles

    NASA Astrophysics Data System (ADS)

    Hong, Yun-Kun; Cho, GeonHee; Park, YoonSu; Oh, Soong Ju; Ha, Don-Hyung

    2018-06-01

    This study investigates the morphological change in colloidal ZnO nanoparticles (NPs) synthesized with trioctylphosphine (TOP). The addition of TOP to the synthesis causes an evolution in the shape of ZnO NPs to tadpole-like particles from quasi-spherical particles at 300 °C. The total length of the tadpole-like ZnO NPs can be modified by controlling the molar ratio of TOP to oleylamine (OLAM). The tadpole-like particles are elongated as the concentration of TOP increased but decreased when the addition of TOP is excessive. These tadpole-like ZnO NPs transform to quasi-spherical NPs regardless of the amount of TOP at a reaction time of 3 h at 300 °C. At 200 °C, the effect of TOP on the ZnO NP synthesis differs from that at 300 °C. The ZnO NPs synthesized by controlling the molar ratios of surfactant ligands (TOP:OLAM = 2:100 and 70:100) at 200 °C share similar amorphous structures, while a crystalline ZnO phase is formed when the reaction time is 3 h. X-ray photoelectron spectroscopy analysis shows that TOP influences the oxidation of ZnO and suggests that a combination of OLAM and TOP plays a role in controlling the shape of ZnO NPs. These results provide critical insights to the utilization of TOP for a shape controlling ligand in ZnO NPs and suggest a new route to design oxide NPs.

  16. Trioctylphosphine-assisted morphology control of ZnO nanoparticles.

    PubMed

    Hong, Yun-Kun; Cho, GeonHee; Park, YoonSu; Oh, Soong Ju; Ha, Don-Hyung

    2018-06-01

    This study investigates the morphological change in colloidal ZnO nanoparticles (NPs) synthesized with trioctylphosphine (TOP). The addition of TOP to the synthesis causes an evolution in the shape of ZnO NPs to tadpole-like particles from quasi-spherical particles at 300 °C. The total length of the tadpole-like ZnO NPs can be modified by controlling the molar ratio of TOP to oleylamine (OLAM). The tadpole-like particles are elongated as the concentration of TOP increased but decreased when the addition of TOP is excessive. These tadpole-like ZnO NPs transform to quasi-spherical NPs regardless of the amount of TOP at a reaction time of 3 h at 300 °C. At 200 °C, the effect of TOP on the ZnO NP synthesis differs from that at 300 °C. The ZnO NPs synthesized by controlling the molar ratios of surfactant ligands (TOP:OLAM = 2:100 and 70:100) at 200 °C share similar amorphous structures, while a crystalline ZnO phase is formed when the reaction time is 3 h. X-ray photoelectron spectroscopy analysis shows that TOP influences the oxidation of ZnO and suggests that a combination of OLAM and TOP plays a role in controlling the shape of ZnO NPs. These results provide critical insights to the utilization of TOP for a shape controlling ligand in ZnO NPs and suggest a new route to design oxide NPs.

  17. Schottky nanocontact of one-dimensional semiconductor nanostructures probed by using conductive atomic force microscopy

    NASA Astrophysics Data System (ADS)

    Lee, Jung Ah; Rok Lim, Young; Jung, Chan Su; Choi, Jun Hee; Im, Hyung Soon; Park, Kidong; Park, Jeunghee; Kim, Gyu Tae

    2016-10-01

    To develop the advanced electronic devices, the surface/interface of each component must be carefully considered. Here, we investigate the electrical properties of metal-semiconductor nanoscale junction using conductive atomic force microscopy (C-AFM). Single-crystalline CdS, CdSe, and ZnO one-dimensional nanostructures are synthesized via chemical vapor transport, and individual nanobelts (or nanowires) are used to fabricate nanojunction electrodes. The current-voltage (I -V) curves are obtained by placing a C-AFM metal (PtIr) tip as a movable contact on the nanobelt (or nanowire), and often exhibit a resistive switching behavior that is rationalized by the Schottky (high resistance state) and ohmic (low resistance state) contacts between the metal and semiconductor. We obtain the Schottky barrier height and the ideality factor through fitting analysis of the I-V curves. The present nanojunction devices exhibit a lower Schottky barrier height and a higher ideality factor than those of the bulk materials, which is consistent with the findings of previous works on nanostructures. It is shown that C-AFM is a powerful tool for characterization of the Schottky contact of conducting channels between semiconductor nanostructures and metal electrodes.

  18. Room temperature synthesis and optical properties of small diameter (5 nm) ZnO nanorod arrays.

    PubMed

    Cho, Seungho; Jang, Ji-Wook; Lee, Jae Sung; Lee, Kun-Hong

    2010-10-01

    We report a simple wet-chemical synthesis of ∼5 nm diameter ZnO nanorod arrays at room temperature (20 °C) and normal atmospheric pressure (1 atm) and their optical properties. They were single crystalline in nature, and grew in the [001] direction. These small diameter ZnO nanorod arrays can also be synthesized at 0 °C. Control experiments were also conducted. On the basis of the results, we propose a mechanism for the spontaneous growth of the small diameter ZnO structures. The optical properties of the 5 nm diameter ZnO nanorod arrays synthesized using this method were probed by UV-Visible diffuse reflectance spectroscopy. A clear blue-shift, relative to the absorption band from 50 nm diameter ZnO nanorod arrays, was attributed to the quantum confinement effects caused by the small nanocrystal size in the 5 nm diameter ZnO nanorods.

  19. Elemental, morphological, structural, optical, and magnetic properties of erbium doped ZnO nanoparticles

    NASA Astrophysics Data System (ADS)

    Poornaprakash, B.; Chalapathi, U.; Purusottam Reddy, B.; Prabhakar Vattikuti, S. V.; Siva Pratap Reddy, M.; Park, Si-Hyun

    2018-03-01

    The sensible tuning of the structural, optical, and magnetic properties of ZnO nanoparticles (NPs) with suitable doping can enhance their applicability in diverse fields. In this study, we synthesized ZnO NPs with Er (0-4 at%) doping and their elemental, structural, optical, and magnetic properties were studied. Both field emission scanning electron microscopy (FESEM) and high resolution transmission electron microscopy (HRTEM) studies of the suspensions consist of hexagonal shaped NPs. All the prepared NPs exhibited hexagonal phase as demonstrated by powder x-ray diffraction studies. A blue shift was observed in the Er doped ZnO NPs compared to pure ZnO, indicating the increased optical bandgap. Vibrating sample magnetometer studies exhibited the pure ZnO NPs was typical diamagnetic feature whereas all the Er doped ZnO NPs were paramagnetic feature at 300 K. This is the first paramagnetic report on Er doped ZnO NPs.

  20. pH effect on structural and optical properties of nanostructured zinc oxide thin films

    SciTech Connect

    Munef, R. A.

    2015-03-30

    ZnO nanostructures were Deposited on Objekttrager glasses for various pH values by chemical bath deposition method using Zn (NO3)2·6H2O (zinc nitrate hexahydrate) solution at 75°C reaction temperature without any posterior treatments. The ZnO nanostructures obtained were characterized by X-ray Diffraction (XRD, UV). The structure was hexagonal and it was found that some peaks disappear with various pH values. The grain sizes of ZnO films increases from 22-to-29nm with increasing pH. The transmission of the films was (85-95%)

  1. Photoluminescent ZnO Nanoparticles and Their Biological Applications

    PubMed Central

    Zhang, Zheng-Yong; Xiong, Huan-Ming

    2015-01-01

    During the past decades, numerous achievements concerning luminescent zinc oxide nanoparticles (ZnO NPs) have been reported due to their improved luminescence and good biocompatibility. The photoluminescence of ZnO NPs usually contains two parts, the exciton-related ultraviolet (UV) emission and the defect-related visible emission. With respect to the visible emission, many routes have been developed to synthesize and functionalize ZnO NPs for the applications in detecting metal ions and biomolecules, biological fluorescence imaging, nonlinear multiphoton imaging, and fluorescence lifetime imaging. As the biological applications of ZnO NPs develop rapidly, the toxicity of ZnO NPs has attracted more and more attention because ZnO can produce the reactive oxygen species (ROS) and release Zn2+ ions. Just as a coin has two sides, both the drug delivery and the antibacterial effects of ZnO NPs become attractive at the same time. Hence, in this review, we will focus on the progress in the synthetic methods, luminescent properties, and biological applications of ZnO NPs.

  2. Silicon-embedded copper nanostructure network for high energy storage

    DOEpatents

    Yu, Tianyue

    2016-03-15

    Provided herein are nanostructure networks having high energy storage, electrochemically active electrode materials including nanostructure networks having high energy storage, as well as electrodes and batteries including the nanostructure networks having high energy storage. According to various implementations, the nanostructure networks have high energy density as well as long cycle life. In some implementations, the nanostructure networks include a conductive network embedded with electrochemically active material. In some implementations, silicon is used as the electrochemically active material. The conductive network may be a metal network such as a copper nanostructure network. Methods of manufacturing the nanostructure networks and electrodes are provided. In some implementations, metal nanostructures can be synthesized in a solution that contains silicon powder to make a composite network structure that contains both. The metal nanostructure growth can nucleate in solution and on silicon nanostructure surfaces.

  3. Silicon-embedded copper nanostructure network for high energy storage

    DOEpatents

    Yu, Tianyue

    2018-01-23

    Provided herein are nanostructure networks having high energy storage, electrochemically active electrode materials including nanostructure networks having high energy storage, as well as electrodes and batteries including the nanostructure networks having high energy storage. According to various implementations, the nanostructure networks have high energy density as well as long cycle life. In some implementations, the nanostructure networks include a conductive network embedded with electrochemically active material. In some implementations, silicon is used as the electrochemically active material. The conductive network may be a metal network such as a copper nanostructure network. Methods of manufacturing the nanostructure networks and electrodes are provided. In some implementations, metal nanostructures can be synthesized in a solution that contains silicon powder to make a composite network structure that contains both. The metal nanostructure growth can nucleate in solution and on silicon nanostructure surfaces.

  4. Superhydrophilic nanostructure

    SciTech Connect

    Mao, Samuel S; Zormpa, Vasileia; Chen, Xiaobo

    2015-05-12

    An embodiment of a superhydrophilic nanostructure includes nanoparticles. The nanoparticles are formed into porous clusters. The porous clusters are formed into aggregate clusters. An embodiment of an article of manufacture includes the superhydrophilic nanostructure on a substrate. An embodiment of a method of fabricating a superhydrophilic nanostructure includes applying a solution that includes nanoparticles to a substrate. The substrate is heated to form aggregate clusters of porous clusters of the nanoparticles.

  5. Synthesis and Characterization of Polymer-Metal Nanostructured Membranes

    DTIC Science & Technology

    ions creating unique polymer -metal nanostructured membranes. A comprehensive materials characterization study was performed to understand their...fluoropolymers were also investigated. First the polymer -metal nanostructure of Nafion with several counter-ions was studied upon supercritical fluid CO2...processing. Then, novel fluorinated block copolymers were synthesized using atom transfer radical polymerization (ATRP) and their resulting nanostructure was

  6. Comparative study of ZnO nanorods and thin films for chemical and biosensing applications and the development of ZnO nanorods based potentiometric strontium ion sensor

    NASA Astrophysics Data System (ADS)

    Khun, K.; Ibupoto, Z. H.; Chey, C. O.; Lu, Jun.; Nur, O.; Willander, M.

    2013-03-01

    In this study, the comparative study of ZnO nanorods and ZnO thin films were performed regarding the chemical and biosensing properties and also ZnO nanorods based strontium ion sensor is proposed. ZnO nanorods were grown on gold coated glass substrates by the hydrothermal growth method and the ZnO thin films were deposited by electro deposition technique. ZnO nanorods and thin films were characterised by field emission electron microscopy [FESEM] and X-ray diffraction [XRD] techniques and this study has shown that the grown nanostructures are highly dense, uniform and exhibited good crystal quality. Moreover, transmission electron microscopy [TEM] was used to investigate the quality of ZnO thin film and we observed that ZnO thin film was comprised of nano clusters. ZnO nanorods and thin films were functionalised with selective strontium ionophore salicylaldehyde thiosemicarbazone [ST] membrane, galactose oxidase, and lactate oxidase for the detection of strontium ion, galactose and L-lactic acid, respectively. The electrochemical response of both ZnO nanorods and thin films sensor devices was measured by using the potentiometric method. The strontium ion sensor has exhibited good characteristics with a sensitivity of 28.65 ± 0.52 mV/decade, for a wide range of concentrations from 1.00 × 10-6 to 5.00 × 10-2 M, selectivity, reproducibility, stability and fast response time of 10.00 s. The proposed strontium ion sensor was used as indicator electrode in the potentiometric titration of strontium ion versus ethylenediamine tetra acetic acid [EDTA]. This comparative study has shown that ZnO nanorods possessed better performance with high sensitivity and low limit of detection due to high surface area to volume ratio as compared to the flat surface of ZnO thin films.

  7. In vitro antibacterial activity of ZnO and Nd doped ZnO nanoparticles against ESBL producing Escherichia coli and Klebsiella pneumoniae

    NASA Astrophysics Data System (ADS)

    Hameed, Abdulrahman Syedahamed Haja; Karthikeyan, Chandrasekaran; Ahamed, Abdulazees Parveez; Thajuddin, Nooruddin; Alharbi, Naiyf S.; Alharbi, Sulaiman Ali; Ravi, Ganasan

    2016-04-01

    Pure ZnO and Neodymium (Nd) doped ZnO nanoparticles (NPs) were synthesized by the co-precipitation method. The synthesized nanoparticles retained the wurtzite hexagonal structure. From FESEM studies, ZnO and Nd doped ZnO NPs showed nanorod and nanoflower like morphology respectively. The FT-IR spectra confirmed the Zn-O stretching bands at 422 and 451 cm-1 for ZnO and Nd doped ZnO NPs respectively. From the UV-VIS spectroscopic measurement, the excitonic peaks were found around 373 nm and 380 nm for the respective samples. The photoluminescence measurements revealed that the broad emission was composed of ten different bands due to zinc vacancies, oxygen vacancies and surface defects. The antibacterial studies performed against extended spectrum β-lactamases (ESBLs) producing strains of Escherichia coli and Klebsiella pneumoniae showed that the Nd doped ZnO NPs possessed a greater antibacterial effect than the pure ZnO NPs. From confocal laser scanning microscopic (CLSM) analysis, the apoptotic nature of the cells was confirmed by the cell shrinkage, disorganization of cell wall and cell membrane and dead cell of the bacteria. SEM analysis revealed the existence of bacterial loss of viability due to an impairment of cell membrane integrity, which was highly consistent with the damage of cell walls.

  8. In vitro antibacterial activity of ZnO and Nd doped ZnO nanoparticles against ESBL producing Escherichia coli and Klebsiella pneumoniae

    PubMed Central

    Hameed, Abdulrahman Syedahamed Haja; Karthikeyan, Chandrasekaran; Ahamed, Abdulazees Parveez; Thajuddin, Nooruddin; Alharbi, Naiyf S.; Alharbi, Sulaiman Ali; Ravi, Ganasan

    2016-01-01

    Pure ZnO and Neodymium (Nd) doped ZnO nanoparticles (NPs) were synthesized by the co-precipitation method. The synthesized nanoparticles retained the wurtzite hexagonal structure. From FESEM studies, ZnO and Nd doped ZnO NPs showed nanorod and nanoflower like morphology respectively. The FT-IR spectra confirmed the Zn-O stretching bands at 422 and 451 cm−1 for ZnO and Nd doped ZnO NPs respectively. From the UV-VIS spectroscopic measurement, the excitonic peaks were found around 373 nm and 380 nm for the respective samples. The photoluminescence measurements revealed that the broad emission was composed of ten different bands due to zinc vacancies, oxygen vacancies and surface defects. The antibacterial studies performed against extended spectrum β-lactamases (ESBLs) producing strains of Escherichia coli and Klebsiella pneumoniae showed that the Nd doped ZnO NPs possessed a greater antibacterial effect than the pure ZnO NPs. From confocal laser scanning microscopic (CLSM) analysis, the apoptotic nature of the cells was confirmed by the cell shrinkage, disorganization of cell wall and cell membrane and dead cell of the bacteria. SEM analysis revealed the existence of bacterial loss of viability due to an impairment of cell membrane integrity, which was highly consistent with the damage of cell walls. PMID:27071382

  9. Surface potential driven dissolution phenomena of [0 0 0 1]-oriented ZnO nanorods grown from ZnO and Pt seed layers

    NASA Astrophysics Data System (ADS)

    Seo, Youngmi; Kim, Jung Hyeun

    2011-06-01

    Highly oriented ZnO nanorods are synthesized hydrothermally on ZnO and Pt seed layers, and they are dissolved in KOH solution. The rods grown on ZnO seed layer show uniform dissolution, but those grown on Pt seed layer are rod-selectively dissolved. The ZnO nanorods from both seed layers show the same crystalline structure through XRD and Raman spectrometer data. However, the surface potential analysis reveals big difference for ZnO and Pt seed cases. The surface potential distribution is very uniform for the ZnO seed case, but it is much fluctuated on the Pt seed case. It suggests that the rod-selective dissolution phenomena on Pt seed case are likely due to the surface energy difference.

  10. Patterned Well-Aligned ZnO Nanorods Assisted with Polystyrene Monolayer by Oxygen Plasma Treatment.

    PubMed

    Choi, Hyun Ji; Lee, Yong-Min; Yu, Jung-Hoon; Hwang, Ki-Hwan; Boo, Jin-Hyo

    2016-08-05

    Zinc oxide is known as a promising material for sensing devices due to its piezoelectric properties. In particular, the alignment of ZnO nanostructures into ordered nanoarrays is expected to improve the device sensitivity due to the large surface area which can be utilized to capture significant quantities of gas particles. However, ZnO nanorods are difficult to grow on the quartz substrate with well-ordered shape. So, we investigated nanostructures by adjusting the interval distance of the arranged ZnO nanorods using polystyrene (PS) spheres of various sizes (800 nm, 1300 nm and 1600 nm). In addition, oxygen plasma treatment was used to specify the nucleation site of round, patterned ZnO nanorod growth. Therefore, ZnO nanorods were grown on a quartz substrate with a patterned polystyrene monolayer by the hydrothermal method after oxygen plasma treatment. The obtained ZnO nanostructures were characterized by X-ray diffraction (XRD) and field-emission scanning electron microscope (FE-SEM).

  11. Seed/catalyst-free vertical growth of high-density electrodeposited zinc oxide nanostructures on a single-layer graphene

    NASA Astrophysics Data System (ADS)

    Aziz, Nur Suhaili Abd; Mahmood, Mohamad Rusop; Yasui, Kanji; Hashim, Abdul Manaf

    2014-02-01

    We report the seed/catalyst-free vertical growth of high-density electrodeposited ZnO nanostructures on a single-layer graphene. The absence of hexamethylenetetramine (HMTA) and heat has resulted in the formation of nanoflake-like ZnO structure. The results show that HMTA and heat are needed to promote the formation of hexagonal ZnO nanostructures. The applied current density plays important role in inducing the growth of ZnO on graphene as well as in controlling the shape, size, and density of ZnO nanostructures. High density of vertically aligned ZnO nanorods comparable to other methods was obtained. The quality of the ZnO nanostructures also depended strongly on the applied current density. The growth mechanism was proposed. According to the growth timing chart, the growth seems to involve two stages which are the formation of ZnO nucleation and the enhancement of the vertical growth of nanorods. ZnO/graphene hybrid structure provides several potential applications in electronics and optoelectronics such as photovoltaic devices, sensing devices, optical devices, and photodetectors.

  12. Designing deoxidation inhibiting encapsulation of metal oxide nanostructures for fluidic and biological applications

    NASA Astrophysics Data System (ADS)

    Ghosh, Moumita; Ghosh, Siddharth; Seibt, Michael; Schaap, Iwan A. T.; Schmidt, Christoph F.; Mohan Rao, G.

    2016-12-01

    Due to their photoluminescence, metal oxide nanostructures such as ZnO nanostructures are promising candidates in biomedical imaging, drug delivery and bio-sensing. To apply them as label for bio-imaging, it is important to study their structural stability in a bio-fluidic environment. We have explored the effect of water, the main constituent of biological solutions, on ZnO nanostructures with scanning electron microscopy (SEM) and photoluminescence (PL) studies which show ZnO nanorod degeneration in water. In addition, we propose and investigate a robust and inexpensive method to encapsulate these nanostructures (without structural degradation) using bio-compatible non-ionic surfactant in non-aqueous medium, which was not reported earlier. This new finding is an immediate interest to the broad audience of researchers working in biophysics, sensing and actuation, drug delivery, food and cosmetics technology, etc.

  13. REVIEW ARTICLE: Structure, microstructure and physical properties of ZnO based materials in various forms: bulk, thin film and nano

    NASA Astrophysics Data System (ADS)

    Singh, Shubra; Thiyagarajan, P.; Mohan Kant, K.; Anita, D.; Thirupathiah, S.; Rama, N.; Tiwari, Brajesh; Kottaisamy, M.; Ramachandra Rao, M. S.

    2007-10-01

    ZnO is a unique material that offers about a dozen different application possibilities. In spite of the fact that the ZnO lattice is amenable to metal ion doping (3d and 4f), the physics of doping in ZnO is not completely understood. This paper presents a review of previous research works on ZnO and also highlights results of our research activities on ZnO. The review pertains to the work on Al and Mg doping for conductivity and band gap tuning in ZnO followed by a report on transition metal (TM) ion doped ZnO. This review also highlights the work on the transport and optical studies of TM ion doped ZnO, nanostructured growth (ZnO polycrystalline and thin films) by different methods and the formation of unique nano- and microstructures obtained by pulsed laser deposition and chemical methods. This is followed by results on ZnO encapsulated Fe3O4 nanoparticles that show promising trends suitable for various applications. We have also reviewed the non-linear characteristic studies of ZnO based heterostructures followed by an analysis on the work carried out on ZnO based phosphors, which include mainly the nanocrystalline ZnO encapsulated SiO2, a new class of phosphor that is suitable for white light emission.

  14. Mg-catalyzed autoclave synthesis of aligned silicon carbide nanostructures.

    PubMed

    Xi, Guangcheng; Liu, Yankuan; Liu, Xiaoyan; Wang, Xiaoqing; Qian, Yitai

    2006-07-27

    In this article, a novel magnesium-catalyzed co-reduction route was developed for the large-scale synthesis of aligned beta-SiC one-dimensional (1D) nanostructures at relative lower temperature (600 degrees C). By carefully controlling the reagent concentrations, we could synthesize beta-SiC rodlike and needlelike nanostructures. The possible growth mechanism of the as-synthesized beta-SiC 1D nanostructures has been investigated. The structure and morphology of the as-synthesized beta-SiC nanostructures are characterized using X-ray diffraction, Fourier transform infrared absorption, and scanning and transmission electron microscopes. Raman and photoluminescence properties are also investigated at room temperature. The as-synthesized beta-SiC nanostructures exhibit strong shape-dependent field emission properties. Corresponding to their shapes, the as-synthesized nanorods and nanoneedles display the turn-on fields of 12, 8.4, and 1.8 V/microm, respectively.

  15. Waveform synthesizer

    DOEpatents

    Franks, Larry A.; Nelson, Melvin A.

    1981-01-01

    A method of producing optical and electrical pulses of desired shape. An optical pulse of arbitrary but defined shape illuminates one end of an array of optical fiber waveguides of differing lengths to time differentiate the input pulse. The optical outputs at the other end of the array are combined to form a synthesized pulse of desired shape.

  16. Efficiency improvement of silicon solar cells enabled by ZnO nanowhisker array coating

    PubMed Central

    2012-01-01

    An efficient antireflection coating is critical for the improvement of silicon solar cell performance via increased light coupling. Here, we have grown well-aligned ZnO nanowhisker (NW) arrays on Czochralski silicon solar cells by a seeding-growth two-step process. It is found that the ZnO NWs have a great effect on the macroscopic antireflection effect and, therefore, improves the solar cell performance. The ZnO NW array-coated solar cells display a broadband reflection suppression from 500 to 1,100 nm, and the minimum reflectance smaller than 3% can easily be achieved. By optimizing the time of ZnO NW growth, it has been confirmed that an increase of 3% relatively in the solar cell efficiency can be obtained. These results are quite interesting for the application of ZnO nanostructure in the fabrication of high-efficiency silicon solar cells. PMID:22704578

  17. Influence of the ZnO nanoarchitecture on the electrochemical performances of binder-free anodes for Li storage

    NASA Astrophysics Data System (ADS)

    Dall'Asta, V.; Tealdi, C.; Resmini, A.; Anselmi Tamburini, U.; Mustarelli, P.; Quartarone, E.

    2017-03-01

    Zinc oxide nanoarchitectures may be employed as binder-free, high specific capacity anodes for lithium batteries. By means of simple and low-impact wet chemistry approaches, we synthesized 1D (nanorods), 2D (single- and multi-layered nanosheets), and 3D (nanobrushes) ZnO arrays. These nanoarchitectures were compared as far as concerns their electrochemical properties and the structural modifications upon lithiation/delithiation. The best results were offered by 2D nanosheets, which showed reversible capacity of the order of 400 mAhg-1 after 100 cycles at 1 Ag-1. This was due to: i) small nanoparticles, with average diameter of about 10 nm, which maximize the array specific surface area and favor the formation of the LiZn alloy; ii) the presence of a mesoporous texture, which allows larger space for accommodating the volume changes upon lithiation/delithiation. However, also these 2D structures showed large irreversible capacity losses. Our work highlights the need for more efficient buffering solutions in ZnO binder-free nanostructured anodes.

  18. The Synthesis of Photocatalyst Material ZnO using the Simple Sonication Method

    NASA Astrophysics Data System (ADS)

    Faradis, R.; Azizah, E. N.; Marella, S. D.; Aini, N.; Prasetyo, A.

    2018-03-01

    ZnO is well known as photocatalyst material therefore potentially to applied in many purposes. The particle size of photocatalyst material influenced the catalytic activities. In this research, ZnO was synthesized using the simple sonication method to obtain the the smaller particle with sonication time variation respectively: 30, 60, 160, 360 minute. X-ray diffraction data showed that the synthesized material have wurtzite structure with space group P63 mc. The synthesized ZnO with 30 minutes sonication time produced the smallest particle size and have the lowest band gap energy (2.79 eV). The photocatalytic test at methylene blue also showed that the optimum activity was gained from ZnO which synthesized at 30 minute sonication time (degradation percentage of metylene blue is 77.93%).

  19. Synthesis, characteristics and antimicrobial activity of ZnO nanoparticles

    NASA Astrophysics Data System (ADS)

    Janaki, A. Chinnammal; Sailatha, E.; Gunasekaran, S.

    2015-06-01

    The utilization of various plant resources for the bio synthesis of metallic nano particles is called green technology and it does not utilize any harmful protocols. Present study focuses on the green synthesis of ZnO nano particles by Zinc Carbonate and utilizing the bio-components of powder extract of dry ginger rhizome (Zingiber officinale). The ZnO nano crystallites of average size range of 23-26 nm have been synthesized by rapid, simple and eco friendly method. Zinc oxide nano particles were characterized by using X-ray diffraction (XRD), Scanning Electron Microscope (SEM), Energy Dispersive X-ray spectroscopy (EDX). FTIR spectra confirmed the adsorption of surfactant molecules at the surface of ZnO nanoparticles and the presence of ZnO bonding. Antimicrobial activity of ZnO nano particles was done by well diffusion method against pathogenic organisms like Klebsiella pneumonia, Staphylococcus aureus and Candida albicans and Penicillium notatum. It is observed that the ZnO synthesized in the process has the efficient antimicrobial activity.

  20. Functional zinc oxide nanostructures for electronic and energy applications

    NASA Astrophysics Data System (ADS)

    Prasad, Abhishek

    ZnO has proven to be a multifunctional material with important nanotechnological applications. ZnO nanostructures can be grown in various forms such as nanowires, nanorods, nanobelts, nanocombs etc. In this work, ZnO nanostructures are grown in a double quartz tube configuration thermal Chemical Vapor Deposition (CVD) system. We focus on functionalized ZnO Nanostructures by controlling their structures and tuning their properties for various applications. The following topics have been investigated: (1) We have fabricated various ZnO nanostructures using a thermal CVD technique. The growth parameters were optimized and studied for different nanostructures. (2) We have studied the application of ZnO nanowires (ZnONWs) for field effect transistors (FETs). Unintentional n-type conductivity was observed in our FETs based on as-grown ZnO NWs. We have then shown for the first time that controlled incorporation of hydrogen into ZnO NWs can introduce p-type characters to the nanowires. We further found that the n-type behaviors remained, leading to the ambipolar behaviors of hydrogen incorporated ZnO NWs. Importantly, the detected p- and n- type behaviors are stable for longer than two years when devices were kept in ambient conditions. All these can be explained by an ab initio model of Zn vacancy-Hydrogen complexes, which can serve as the donor, acceptors, or green photoluminescence quencher, depend on the number of hydrogen atoms involved. (3) Next ZnONWs were tested for electron field emission. We focus on reducing the threshold field (Eth) of field emission from non-aligned ZnO NWs. As encouraged by our results on enhancing the conductivity of ZnO NWs by hydrogen annealing described in Chapter 3, we have studied the effect of hydrogen annealing for improving field emission behavior of our ZnO NWs. We found that optimally annealed ZnO NWs offered much lower threshold electric field and improved emission stability. We also studied field emission from ZnO NWs at moderate

  1. Synthesis of ZnO nanorods and observation of resistive switching memory in ZnO based polymer nanocomposites

    NASA Astrophysics Data System (ADS)

    Nair, Manjula G.; Malakar, Meenakshi; Mohapatra, Saumya R.; Chowdhury, Avijit

    2018-05-01

    This research reports the observation of bipolar resistive switching memory in ZnO nanorod based polymer nanocomposites. We synthesized ZnO nanorods by wet-chemical method and characterized them using XRD, UV-VIS spectroscopy and SEM. The synthesized materials have hexagonal ZnO phase with grain size of 24 nm and having strong orientation along (101) direction as observed from XRD. The SEM micrograph confirms the formation of ZnO nanorods with diameter in the range of 10 to 20 nm and length of the order of 1 µm. From optical absorption spectra the band gap is estimated to be 2.42 eV. ZnO nanorods were dispersed in PVDF-HFP polymer matrix to prepare the nanocomposite. This nanocomposite was used as active layer in the devices having sandwich structure of ITO/PVDF-HFP+ZnO nanorods/Al. Bipolar non-volatile memory was observed with ON-OFF resistance ratio of the order of 103 and with a wide voltage window of 2.3V. The switching mechanism could be due to the trapping and de-trapping of electrons by the ZnO nanorods in the nanocomposite during ON and OFF states respectively.

  2. Hexagonal and prismatic nanowalled ZnO microboxes.

    PubMed

    Zhao, Fenghua; Lin, Wenjiao; Wu, Mingmei; Xu, Ningsheng; Yang, Xianfeng; Tian, Z Ryan; Su, Qiang

    2006-04-17

    We hereby report hydrothermal syntheses of new microstructures of semiconducting ZnO. Single-crystalline prismatic ZnO microboxes formed by nanowalls and hexagonal hollow microdisks closed by plates with micron-sized inorganic fullerene-like structures have been made in a base-free medium through a one-step hydrothermal synthesis with the help of n-butanol (NB). Structures and morphologies of the products were confirmed by results from powder X-ray diffraction and scanning electron microscopy. NB has been found to play a crucial role in the growth of these hollow structures. It is indicated that these hollow ZnO crystals were grown from redissolution of interiors. These ZnO microboxes exhibit a band emission in the visible range, implying the possession of a high content of defects.

  3. Enhanced antimicrobial activity in biosynthesized ZnO nanoparticles

    NASA Astrophysics Data System (ADS)

    Kumari, Niraj; Kumari, Priti; Jha, Anal K.; Prasad, K.

    2018-05-01

    Biological synthesis of different metallic and/or oxide nanoparticles and their applications especially in agriculture and biomedical sciences are gaining prominence nowadays due to their handy and reproducible synthetic protocols which are cost-effective and eco-friendly. In this work, green synthesis of zinc oxide nanoparticles (ZnO NPs) using the alcoholic extract of Azadirachta indica as a reducing and stabilizing agent has been presented. Formation of ZnO NPs was confirmed by X-ray diffraction, scanning and transmission electron microscopy techniques. The phytochemicals responsible for nano-transformation were principally alkaloids, flavanoids, terpenoids, tannins and organic acids present in the Azadirachta indica leaves. The synthesized ZnO NPs were used for antimicrobial assays by disc diffusion method against Staphylococcus aureus and Candida albicans. Results showed that ZnO NPs may act as antimicrobial agent especially against skin infections.

  4. Application of Nanostructures in Electrochromic Materials and Devices: Recent Progress.

    PubMed

    Wang, Jin Min; Sun, Xiao Wei; Jiao, Zhihui

    2010-11-26

    The recent progress in application of nanostructures in electrochromic materials and devices is reviewed. ZnO nanowire array modified by viologen and WO₃, crystalline WO₃ nanoparticles and nanorods, mesoporous WO₃ and TiO₂, poly(3,4-ethylenedioxythiophene) nanotubes, Prussian blue nanoinks and nanostructures in switchable mirrors are reviewed. The electrochromic properties were significantly enhanced by applying nanostructures, resulting in faster switching responses, higher stability and higher optical contrast. A perspective on the development trends in electrochromic materials and devices is also proposed.

  5. Application of Nanostructures in Electrochromic Materials and Devices: Recent Progress

    PubMed Central

    Wang, Jinmin; Sun, Xiao Wei; Jiao, Zhihui

    2010-01-01

    The recent progress in application of nanostructures in electrochromic materials and devices is reviewed. ZnO nanowire array modified by viologen and WO3, crystalline WO3 nanoparticles and nanorods, mesoporous WO3 and TiO2, poly(3,4-ethylenedioxythiophene) nanotubes, Prussian blue nanoinks and nanostructures in switchable mirrors are reviewed. The electrochromic properties were significantly enhanced by applying nanostructures, resulting in faster switching responses, higher stability and higher optical contrast. A perspective on the development trends in electrochromic materials and devices is also proposed. PMID:28883368

  6. Ag nanoparticle-ZnO nanowire hybrid nanostructures as enhanced and robust antimicrobial textiles via a green chemical approach

    NASA Astrophysics Data System (ADS)

    Li, Zhou; Tang, Haoying; Yuan, Weiwei; Song, Wei; Niu, Yongshan; Yan, Ling; Yu, Min; Dai, Ming; Feng, Siyu; Wang, Menghang; Liu, Tengjiao; Jiang, Peng; Fan, Yubo; Wang, Zhong Lin

    2014-04-01

    A new approach for fabrication of a long-term and recoverable antimicrobial nanostructure/textile hybrid without increasing the antimicrobial resistance is demonstrated. Using in situ synthesized Ag nanoparticles (NPs) anchored on ZnO nanowires (NWs) grown on textiles by a ‘dip-in and light-irradiation’ green chemical method, we obtained ZnONW@AgNP nanocomposites with small-size and uniform Ag NPs, which have shown superior performance for antibacterial applications. These new Ag/ZnO/textile antimicrobial composites can be used for wound dressings and medical textiles for topical and prophylactic antibacterial treatments, point-of-use water treatment to improve the cleanliness of water and antimicrobial air filters to prevent bioaerosols accumulating in ventilation, heating, and air-conditioning systems.

  7. Investigation on dielectrophoretic assembly of nanostructures and its application on chemical sensors

    NASA Astrophysics Data System (ADS)

    Tao, Quan

    Because of their extraordinary characteristics such as quantum confinement and large surface-tovolume ratio, semiconducting nanostructures such as nanowires or nanotubes hold great potential in sensing chemical vapors. Nanowire or nanotube based gas sensors usually possess appealing advantages such as high sensitivity, high stability, fast recovery time, and electrically controllable properties. To better predict the composition and concentration of target gas, nanostructures made from heterogeneous materials are employed to provide more predictors. In recent years, nanowires and nanotubes can be synthesized routinely through different methods. The techniques of fabricating nanowire or nanotube based sensor arrays, however, encounter obstacles and deserve further investigations. Dielectrophoresis (DEP), which refers to the motion of submicron particles inside a non-uniform electric field, has long been recognized as a nondestructive, easily implementable, and efficient approach to manipulate nanostructures onto electronic circuitries. However, due to our limited understandings, devices fabricated through DEP often end up with unpredictable number of arbitrarily aligned nanostructures. In this study, we first optimize the classical DEP formulas such that it can be applied to a more general case that a nanostructure is subjected to a non-uniform electric field with arbitrary orientation. A comprehensive model is then constructed to investigate the trajectory and alignment of DEP assembled nanostructures, which can be verified by experimental observations. The simulation results assist us to fabricate a gas sensor array with zinc oxide (ZnO) nanowires and carbon nanotubes (CNTs). It is then demonstrated that the device can well sense ammonia (NH3) at room temperature, which circumvents the usually required high temperature condition for nanowire based gas sensor application. An effective approach to recover the device using DC biases to locally heat up the

  8. Theoretical prediction of low-density hexagonal ZnO hollow structures

    SciTech Connect

    Tuoc, Vu Ngoc, E-mail: tuoc.vungoc@hust.edu.vn; Huan, Tran Doan; Thao, Nguyen Thi

    2016-10-14

    Along with wurtzite and zinc blende, zinc oxide (ZnO) has been found in a large number of polymorphs with substantially different properties and, hence, applications. Therefore, predicting and synthesizing new classes of ZnO polymorphs are of great significance and have been gaining considerable interest. Herein, we perform a density functional theory based tight-binding study, predicting several new series of ZnO hollow structures using the bottom-up approach. The geometry of the building blocks allows for obtaining a variety of hexagonal, low-density nanoporous, and flexible ZnO hollow structures. Their stability is discussed by means of the free energy computed within the lattice-dynamicsmore » approach. Our calculations also indicate that all the reported hollow structures are wide band gap semiconductors in the same fashion with bulk ZnO. The electronic band structures of the ZnO hollow structures are finally examined in detail.« less

  9. Magnetic properties of Sn-substituted Ni-Zn ferrites synthesized from nano-sized powders of NiO, ZnO, Fe2O3, and SnO2

    NASA Astrophysics Data System (ADS)

    Ali, MA; Uddin, MM; Khan, MNI; Chowdhury, FUZ; Hoque, SM; Liba, SI

    2017-06-01

    A series of Ni0.6-x/2Zn0.4-x/2Sn x Fe2O4 (x = 0.0, 0.05, 0.1, 0.15, 0.2, and 0.3) (NZSFO) ferrite composities have been synthesized from nano powders using a standard solid state reaction technique. The spinel cubic structure of the investigated samples has been confirmed by x-ray diffraction (XRD). The magnetic properties such as saturation magnetization ({M}{{s}}), remanent magnetization ({M}{{r}}), coercive field ({H}{{c}}), and Bohr magneton (μ) are calculated from the hysteresis loops. The value of {M}{{s}} is found to decrease with increasing Sn content in the samples. This change is successfully explained by the variation of A-B interaction strength due to Sn substitution in different sites. The compositional stability and quality of the prepared ferrite composites have also been endorsed by the fairly constant initial permeability ({μ }^{\\prime }) over a wide range of frequency. The decreasing trend of {μ }^{\\prime } with increasing Sn content has been observed. Curie temperature {T}{{C}} has been found to increase with the increase in Sn content. A wide spread frequency utility zone indicates that the NZSFO can be considered as a good candidate for use in broadband pulse transformers and wide band read-write heads for video recording. The composition of x = 0.05 shows unusual results and the possible reason is also mentioned with the established formalism.

  10. Lattice diffusion and vapor solid growths forming nanoarchitectures on ZnO nanowires

    NASA Astrophysics Data System (ADS)

    Sombrio, Guilherme; Rivaldo-Gómez, C. M.; Pomar, Cesar A. D.; Souza, Jose A.

    2017-12-01

    We report hierarchical nanoarchitectures formed on the tips and sidewalls of ZnO nanowires which is formed on the top of microtubes. The whole growth process of these micro/nanostructures during thermal oxidation combines lattice/grain/surface ionic diffusion along with vapor solid mechanism. All the process takes place along with the presence of an electric current, which plays an important role forming the ZnO molecules due to Zn metal evaporation and attracting them to condense into nanostructures of several morphologies. The observation of a very long needle-like nanowire reveals the stack nature of the growth. These nanoarchitectures are rarely observed experimentally. Raman scattering confirms phonon confinement in the nanostructures. Photoluminescence measurements indicate a route for engineering defects on the surface of ZnO microtubes after the complete coalescence of the nanostructures through heat treatment. This experiment would be useful for improving nanostructure organization which could provide an impact in the manufacturability of nanostructure-based systems.

  11. Effect of nanocomposite packaging containing ZnO on growth of Bacillus subtilis and Enterobacter aerogenes.

    PubMed

    Esmailzadeh, Hakimeh; Sangpour, Parvaneh; Shahraz, Farzaneh; Hejazi, Jalal; Khaksar, Ramin

    2016-01-01

    Recent advances in nanotechnology have opened new windows in active food packaging. Nano-sized ZnO is an inexpensive material with potential antimicrobial properties. The aim of the present study is to evaluate the antibacterial effect of low density Polyethylene (LDPE) containing ZnO nanoparticles on Bacillus subtilis and Enterobacter aerogenes. ZnO nanoparticles have been synthesized by facil molten salt method and have been characterized by X-ray diffraction (XRD), and scanning electron microscopy (SEM). Nanocomposite films containing 2 and 4 wt.% ZnO nanoparticles were prepared by melt mixing in a twin-screw extruder. The growth of both microorganisms has decreased in the presence of ZnO containing nanocomposites compared with controls. Nanocomposites with 4 wt.% ZnO nanoparticles had stronger antibacterial effect against both bacteria in comparison with the 2 wt.% ZnO containing nanocomposites. B. subtilis as Gram-positive bacteria were more sensitive to ZnO containing nanocomposite films compared with E. aerogenes as Gram-negative bacteria. There were no significant differences between the migration of Zn ions from 2 and 4 wt.% ZnO containing nanocomposites and the released Zn ions were not significantly increased in both groups after 14 days compared with the first. Regarding the considerable antibacterial effects of ZnO nanoparticles, their application in active food packaging can be a suitable solution for extending the shelf life of food. Copyright © 2015. Published by Elsevier B.V.

  12. Characterization of spatial manipulation on ZnO nanocomposites consisting of Au nanoparticles, a graphene layer, and ZnO nanorods

    NASA Astrophysics Data System (ADS)

    Huang, Shen-Che; Lu, Chien-Cheng; Su, Wei-Ming; Weng, Chen-Yuan; Chen, Yi-Cian; Wang, Shing-Chung; Lu, Tien-Chang; Chen, Ching-Pang; Chen, Hsiang

    2018-01-01

    Three types of ZnO-based nanocomposites were fabricated consisting of 80-nm Au nanoparticles (NPs), a graphene layer, and ZnO nanorods (NRs). To investigate interactions between the ZnO NRs and Au nanoparticle, multiple material analysis techniques including field-emission scanning electron microscopy (FESEM), surface contact angle measurements, secondary ion mass spectrometry (SIMS), X-ray photoelectron spectroscopy (XPS), and Raman spectroscopic characterizations were performed. Results indicate that incorporating a graphene layer could block the interaction between the ZnO NRs and the Au NPs. Furthermore, the Raman signal of the Au NPs could be enhanced by inserting a graphene layer on top of the ZnO NRs. Investigation of these graphene-incorporated nanocomposites would be helpful to future studies of the physical properties and Raman analysis of the ZnO-based nanostructure design.

  13. Matrix-assisted energy conversion in nanostructured piezoelectric arrays

    DOEpatents

    Sirbuly, Donald J.; Wang, Xianying; Wang, Yinmin

    2013-01-01

    A nanoconverter is capable of directly generating electricity through a nanostructure embedded in a polymer layer experiencing differential thermal expansion in a stress transfer zone. High surface-to-volume ratio semiconductor nanowires or nanotubes (such as ZnO, silicon, carbon, etc.) are grown either aligned or substantially vertically aligned on a substrate. The resulting nanoforest is then embedded with the polymer layer, which transfers stress to the nanostructures in the stress transfer zone, thereby creating a nanostructure voltage output due to the piezoelectric effect acting on the nanostructure. Electrodes attached at both ends of the nanostructures generate output power at densities of .about.20 nW/cm.sup.2 with heating temperatures of .about.65.degree. C. Nanoconverters arrayed in a series parallel arrangement may be constructed in planar, stacked, or rolled arrays to supply power to nano- and micro-devices without use of external batteries.

  14. ZnO nanoparticles based fiber optic gas sensor

    SciTech Connect

    Narasimman, S.; Sivacoumar, R.; Alex, Z. C.

    In this work, ZnO nanoparticles were synthesized by simple aqueous chemical route method. The synthesized ZnO nanoparticles were characterized by X-ray diffraction and scanning electron microscope. The sensitivity of the nanoparticles was studied for different gases like acetone, ammonia and ethanol in terms of variation in spectral light intensity. The XRD and SEM analysis confirms the formation of hexagonal wurtzite structure with the grain size of 11.2 nm. The small cladding region of the optical fiber was replaced with the synthesized nanoparticles. The light spectrum was recorded for different gas concentrations. The synthesized nanoparticles showed high sensitivity towards ammonia in lowmore » ppm level and acetone in high ppm level.« less

  15. The effect of Cu doping on the mechanical and optical properties of zinc oxide nanowires synthesized by hydrothermal route.

    PubMed

    Robak, Elżbieta; Coy, Emerson; Kotkowiak, Michał; Jurga, Stefan; Załęski, Karol; Drozdowski, Henryk

    2016-04-29

    Zinc oxide (ZnO) is a wide-bandgap semiconductor material with applications in a variety of fields such as electronics, optoelectronic and solar cells. However, much of these applications demand a reproducible, reliable and controllable synthesis method that takes special care of their functional properties. In this work ZnO and Cu-doped ZnO nanowires are obtained by an optimized hydrothermal method, following the promising results which ZnO nanostructures have shown in the past few years. The morphology of as-prepared and copper-doped ZnO nanostructures is investigated by means of scanning electron microscopy and high resolution transmission electron microscopy. X-ray diffraction is used to study the impact of doping on the crystalline structure of the wires. Furthermore, the mechanical properties (nanoindentation) and the functional properties (absorption and photoluminescence measurements) of ZnO nanostructures are examined in order to assess their applicability in photovoltaics, piezoelectric and hybrids nanodevices. This work shows a strong correlation between growing conditions, morphology, doping and mechanical as well as optical properties of ZnO nanowires.

  16. Systematic study of inorganic functionalization of ZnO nanorods by Sol-Gel method

    NASA Astrophysics Data System (ADS)

    Gamarra, J. K.; Solano, C.; Piñeres, I.; Gómez, H.; Mass, J.; Montenegro, D. N.

    2017-01-01

    A systematic study of the inorganic surface functionalization of ZnO nanostructures by sol-gel method is shown. We have emphasized on the evolution of morphology properties of samples as a function of functionalization parameters. In addition, the effects on thermal stability and some optical properties of samples are discussed.

  17. Au functionalized ZnO rose-like hierarchical structures and their enhanced NO2 sensing performance

    NASA Astrophysics Data System (ADS)

    Shingange, K.; Swart, H. C.; Mhlongo, G. H.

    2018-04-01

    Herein, we present ZnO rose-like hierarchical nanostructures employed as support to Au nanoparticles to produce Au functionalized three dimensional (3D) ZnO hierarchical nanostructures (Au/ZnO) for NO2 detection using a microwave-assisted method. Comparative analysis of NO2 sensing performance between the pristine ZnO and Au/ZnO rose-like structures at 300 °C revealed improved NO2 response and rapid response-recovery times with Au incorporation owing to a combination of high surface accessibility induced by hierarchical nanostructure design and catalytic activity of the small Au nanoparticles. Structural and optical analyses acquired from X-ray diffraction, scanning electron microscopy, transmission electron microscope and photoluminescence spectroscopy were also performed.

  18. ZnO nanomaterials based surface acoustic wave ethanol gas sensor.

    PubMed

    Wu, Y; Li, X; Liu, J H; He, Y N; Yu, L M; Liu, W H

    2012-08-01

    ZnO nanomaterials based surface acoustic wave (SAW) gas sensor has been investigated in ethanol environment at room temperature. The ZnO nanomaterials have been prepared through thermal evaporation of high-purity zinc powder. The as-prepared ZnO nanomaterials have been characterized with scanning electron microscopy (SEM), transmission electron microscopy (TEM) and X-ray Diffraction (XRD) techniques. The results indicate that the obtained ZnO nanomaterials, including many types of nanostructures such as nanobelts, nanorods, nanowires as well as nanosheets, are wurtzite with hexagonal structure and well-crystallized. The SAW sensor coated with the nanostructured ZnO materials has been tested in ethanol gas of various concentrations at room temperature. A network analyzer is used to monitor the change of the insertion loss of the SAW sensor when exposed to ethanol gas. The insertion loss of the SAW sensor varies significantly with the change of ethanol concentration. The experimental results manifest that the ZnO nanomaterials based SAW ethanol gas sensor exhibits excellent sensitivity and good short-term reproducibility at room temperature.

  19. Flower-Like CuO/ZnO Hybrid Hierarchical Nanostructures Grown on Copper Substrate: Glycothermal Synthesis, Characterization, Hydrophobic and Anticorrosion Properties

    PubMed Central

    Beshkar, Farshad; Khojasteh, Hossein; Salavati-Niasari, Masoud

    2017-01-01

    In this work we have demonstrated a facile formation of CuO nanostructures on copper substrates by the oxidation of copper foil in ethylene glycol (EG) at 80 °C. On immersing a prepared CuO film into a solution containing 0.1 g Zn(acac)2 in 20 mL EG for 8 h, ZnO flower-like microstructures composed of hierarchical three-dimensional (3D) aggregated nanoparticles and spherical architectures were spontaneously formed at 100 °C. The as-synthesized thin films and 3D microstructures were characterized using XRD, SEM, and EDS techniques. The effects of sodium dodecyl sulphate (SDS), cetyltrimethylammonium bromide (CTAB), and polyethylene glycol (PEG) 6000 as surfactants and stabilizers on the morphology of the CuO and ZnO structures were discussed. Possible growth mechanisms for the controlled organization of primary building units into CuO nanostructures and 3D flower-like ZnO architectures were proposed. The hydrophobic property of the products was characterized by means of water contact angle measurement. After simple surface modification with stearic acid and PDMS, the resulting films showed hydrophobic and even superhydrophobic characteristics due to their special surface energy and nano-microstructure morphology. Importantly, stable superhydrophobicity with a contact angle of 153.5° was successfully observed for CuO-ZnO microflowers after modification with PDMS. The electrochemical impedance measurements proved that the anticorrosion efficiency for the CuO/ZnO/PDMS sample was about 99%. PMID:28773056

  20. Flower-Like CuO/ZnO Hybrid Hierarchical Nanostructures Grown on Copper Substrate: Glycothermal Synthesis, Characterization, Hydrophobic and Anticorrosion Properties.

    PubMed

    Beshkar, Farshad; Khojasteh, Hossein; Salavati-Niasari, Masoud

    2017-06-25

    In this work we have demonstrated a facile formation of CuO nanostructures on copper substrates by the oxidation of copper foil in ethylene glycol (EG) at 80 °C. On immersing a prepared CuO film into a solution containing 0.1 g Zn(acac)₂ in 20 mL EG for 8 h, ZnO flower-like microstructures composed of hierarchical three-dimensional (3D) aggregated nanoparticles and spherical architectures were spontaneously formed at 100 °C. The as-synthesized thin films and 3D microstructures were characterized using XRD, SEM, and EDS techniques. The effects of sodium dodecyl sulphate (SDS), cetyltrimethylammonium bromide (CTAB), and polyethylene glycol (PEG) 6000 as surfactants and stabilizers on the morphology of the CuO and ZnO structures were discussed. Possible growth mechanisms for the controlled organization of primary building units into CuO nanostructures and 3D flower-like ZnO architectures were proposed. The hydrophobic property of the products was characterized by means of water contact angle measurement. After simple surface modification with stearic acid and PDMS, the resulting films showed hydrophobic and even superhydrophobic characteristics due to their special surface energy and nano-microstructure morphology. Importantly, stable superhydrophobicity with a contact angle of 153.5° was successfully observed for CuO-ZnO microflowers after modification with PDMS. The electrochemical impedance measurements proved that the anticorrosion efficiency for the CuO/ZnO/PDMS sample was about 99%.

  1. Synthesis of p-type ZnO films

    NASA Astrophysics Data System (ADS)

    Ryu, Y. R.; Zhu, S.; Look, D. C.; Wrobel, J. M.; Jeong, H. M.; White, H. W.

    2000-06-01

    p-Type ZnO obtained by arsenic (As) doping is reported for the first time. Arsenic-doped ZnO (ZnO : As) films have been deposited on (0 0 1)-GaAs substrates by pulsed laser ablation. The process of synthesizing p-type ZnO : As films was performed in an ambient gas of ultra-pure (99.999%) oxygen. The ambient gas pressure was 35 mTorr with the substrate temperature in the range 300-450°C. ZnO films grown at 400°C and 450°C are p-type and As is a good acceptor. The acceptor peak is located at 3.32 eV and its binding energy is about 100 meV. Acceptor concentrations of As atoms in ZnO films were in the range from high 10 17 to high 10 21 atoms/cm 3 as determined by secondary ion mass spectroscopy (SIMS) and Hall effect measurements.

  2. Enhanced light absorption of silicon solar cells with dielectric nanostructured back reflector

    NASA Astrophysics Data System (ADS)

    Ren, Rui; Zhong, Zheng

    2018-06-01

    This paper investigates the light absorption property of nanostructured dielectric reflectors in silicon thin film solar cells using numerical simulation. Flat thin film solar cell with ZnO nanostructured back reflector can produce comparable photocurrent to the control model with Ag nanostructured back reflector. Furthermore, when it is integrated with nano-pillar surface decoration, a photocurrent density of 29.5 mA/cm2 can be achieved, demonstrating a photocurrent enhancement of 5% as compared to the model with Ag nanostructured back reflector.

  3. Zinc oxide hollow microstructures and nanostructures formed under hydrothermal conditions

    SciTech Connect

    Dem'yanets, L. N., E-mail: demianets@ns.crys.ras.ru; Artemov, V. V.; Li, L. E.

    Zinc oxide low-dimensional hollow structures in the form of hexagonal plates with holes at the center of the {l_brace}0001{r_brace} facets are synthesized in the course of the low-temperature interaction of ZnO precursors with aqueous solutions of potassium fluoride under hydrothermal conditions. Crystals have the shape of single-walled or multiwalled 'nuts.' The high optical quality of the structures is confirmed by cathodoluminescence data at room temperature. The mechanism of the formation of ZnO 'nanonuts' and products of the interaction of the ZnO precursors with KF is proposed.

  4. Electromechanical phenomena in semiconductor nanostructures

    NASA Astrophysics Data System (ADS)

    Lew Yan Voon, L. C.; Willatzen, M.

    2011-02-01

    Electromechanical phenomena in semiconductors are still poorly studied from a fundamental and an applied science perspective, even though significant strides have been made in the last decade or so. Indeed, most current electromechanical devices are based on ferroelectric oxides. Yet, the importance of the effect in certain semiconductors is being increasingly recognized. For instance, the magnitude of the electric field in an AlN/GaN nanostructure can reach 1-10 MV/cm. In fact, the basic functioning of an (0001) AlGaN/GaN high electron mobility transistor is due to the two-dimensional electron gas formed at the material interface by the polarization fields. The goal of this review is to inform the reader of some of the recent developments in the field for nanostructures and to point out still open questions. Examples of recent work that involves the piezoelectric and pyroelectric effects in semiconductors include: the study of the optoelectronic properties of III-nitrides quantum wells and dots, the current controversy regarding the importance of the nonlinear piezoelectric effect, energy harvesting using ZnO nanowires as a piezoelectric nanogenerator, the use of piezoelectric materials in surface acoustic wave devices, and the appropriateness of various models for analyzing electromechanical effects. Piezoelectric materials such as GaN and ZnO are gaining more and more importance for energy-related applications; examples include high-brightness light-emitting diodes for white lighting, high-electron mobility transistors, and nanogenerators. Indeed, it remains to be demonstrated whether these materials could be the ideal multifunctional materials. The solutions to these and other related problems will not only lead to a better understanding of the basic physics of these materials, but will validate new characterization tools, and advance the development of new and better devices. We will restrict ourselves to nanostructures in the current article even though the

  5. Anomalous antibacterial activity and dye degradation by selenium doped ZnO nanoparticles.

    PubMed

    Dutta, Raj Kumar; Nenavathu, Bhavani Prasad; Talukdar, Soumita

    2014-02-01

    Selenium doped ZnO nanoparticles synthesized by mechanochemical method were spherically shaped of size distribution of 10.2±3.4 nm measured by transmission electron microscopy. Diffused reflectance spectroscopy revealed increase in the band gap, ranging between 3.47 eV and 3.63 eV due to Se doping in ZnO nanoparticles. The antibacterial activity of pristine and Se doped ZnO nanoparticles was attributed to ROS (reactive oxygen species) generation in culture media confirmed by TBARS assay. Compared to complete inhibition of growth by 0.45 mg/mL of pristine ZnO nanoparticles, the batches of 0.45 mg/mL of selenium doped ZnO nanoparticles exhibited only 51% inhibition of growth of Escherichia coli. The reduced antibacterial activity of selenium doped ZnO nanoparticles was attributed to two opposing factors, e.g., ROS generation for inhibition of growth, countered by sustaining growth of E. coli due to availability of Se micronutrients in culture media, confirmed by inductively coupled plasma mass spectrometer measurement. Higher ROS generation by selenium doped ZnO nanoparticles was attributed to creation of oxygen vacancies, confirmed from green emission peak observed at 565 nm. The impact of higher ROS generation by selenium doped ZnO nanoparticles was evident from enhanced photocatalytic degradation of trypan blue dye, than pristine ZnO nanoparticles. Copyright © 2013 Elsevier B.V. All rights reserved.

  6. Fabrication Methods and Luminescent Properties of ZnO Materials for Light-Emitting Diodes

    PubMed Central

    Lee, Ching-Ting

    2010-01-01

    Zinc oxide (ZnO) is a potential candidate material for optoelectronic applications, especially for blue to ultraviolet light emitting devices, due to its fundamental advantages, such as direct wide band gap of 3.37 eV, large exciton binding energy of 60 meV, and high optical gain of 320 cm−1 at room temperature. Its luminescent properties have been intensively investigated for samples, in the form of bulk, thin film, or nanostructure, prepared by various methods and doped with different impurities. In this paper, we first review briefly the recent progress in this field. Then a comprehensive summary of the research carried out in our laboratory on ZnO preparation and its luminescent properties, will be presented, in which the involved samples include ZnO films and nanorods prepared with different methods and doped with n-type or p-type impurities. The results of ZnO based LEDs will also be discussed.

  7. Control of the ZnO nanowires nucleation site using microfluidic channels.

    PubMed

    Lee, Sang Hyun; Lee, Hyun Jung; Oh, Dongcheol; Lee, Seog Woo; Goto, Hiroki; Buckmaster, Ryan; Yasukawa, Tomoyuki; Matsue, Tomokazu; Hong, Soon-Ku; Ko, HyunChul; Cho, Meoung-Whan; Yao, Takafumi

    2006-03-09

    We report on the growth of uniquely shaped ZnO nanowires with high surface area and patterned over large areas by using a poly(dimethylsiloxane) (PDMS) microfluidic channel technique. The synthesis uses first a patterned seed template fabricated by zinc acetate solution flowing though a microfluidic channel and then growth of ZnO nanowire at the seed using thermal chemical vapor deposition on a silicon substrate. Variations the ZnO nanowire by seed pattern formed within the microfluidic channel were also observed for different substrates and concentrations of the zinc acetate solution. The photocurrent properties of the patterned ZnO nanowires with high surface area, due to their unique shape, were also investigated. These specialized shapes and patterning technique increase the possibility of realizing one-dimensional nanostructure devices such as sensors and optoelectric devices.

  8. Synthesis of stable ZnO nanocolloids with enhanced optical limiting properties via simple solution method

    NASA Astrophysics Data System (ADS)

    Ramya, M.; Nideep, T. K.; Vijesh, K. R.; Nampoori, V. P. N.; Kailasnath, M.

    2018-07-01

    In present work, we report the synthesis of stable ZnO nanocolloids through a simple solution method which exhibit enhanced optical limiting threshold. The influences of reaction temperature on the crystal structure as well as linear and nonlinear optical properties of prepared ZnO nanoparticles were carried out. The XRD and Raman analysis reveal that the prepared ZnO nanoparticles retain the hexagonal wurtzite crystal structure. HRTEM analysis confirms the effect of reaction temperature, solvent effect on crystallinity as well as nanostructure of ZnO nanoparticles. It has been found that crystallinity and average diameter increase with reaction temperature where ethylene glycol act as both solvent and growth inhibiter. EDS spectra shows formation of pure ZnO nanoparticles. The direct energy band gap of the nanoparticles increases with decrease in particle size due to quantum confinement effect. The third order nonlinear optical properties of ZnO nanoparticles were investigated by z scan technique using a frequency doubled Nd-YAG nanosecond laser at 532 nm wavelength. The z-scan result reveals that the prepared ZnO nanoparticles exhibit self - defocusing nonlinearity. The two photon absorption coefficient and third - order nonlinear optical susceptibility increases with increasing particle size. The third-order susceptibility of the ZnO nanoparticles is found to be in the order of 10-10 esu, which is at least three order magnitude greater than the bulk ZnO. The optical limiting threshold of the nanoparticles varies in the range of 54 to 17 MW/cm2. The results suggest that ZnO nanoparticles considered as a promising candidates for the future photonic devices.

  9. Improvement in LPG sensing response by surface activation of ZnO thick films with Cr2O3

    NASA Astrophysics Data System (ADS)

    Hastir, Anita; Virpal, Kaur, Jasmeet; Singh, Gurpreet; Kohli, Nipin; Singh, Onkar; Singh, Ravi Chand

    2015-05-01

    Liquefied Petroleum Gas (LPG) sensing response of pure and Cr2O3 activated ZnO has been investigated in this study. Zinc oxide was synthesized by co-precipitation route and deposited as a thick film on an alumina substrate. The surface of ZnO sensor was activated by chromium oxide on surface oxidation by chromium chloride. The concentration of chromium chloride solution used to activate the ZnO sensor surface has been varied from 0 to 5 %. It is observed that response to LPG has improved as compared to pure ZnO.

  10. A mixture toxicity approach to predict the toxicity of Ag decorated ZnO nanomaterials.

    PubMed

    Azevedo, S L; Holz, T; Rodrigues, J; Monteiro, T; Costa, F M; Soares, A M V M; Loureiro, S

    2017-02-01

    Nanotechnology is a rising field and nanomaterials can now be found in a vast variety of products with different chemical compositions, sizes and shapes. New nanostructures combining different nanomaterials are being developed due to their enhancing characteristics when compared to nanomaterials alone. In the present study, the toxicity of a nanostructure composed by a ZnO nanomaterial with Ag nanomaterials on its surface (designated as ZnO/Ag nanostructure) was assessed using the model-organism Daphnia magna and its toxicity predicted based on the toxicity of the single components (Zn and Ag). For that ZnO and Ag nanomaterials as single components, along with its mixture prepared in the laboratory, were compared in terms of toxicity to ZnO/Ag nanostructures. Toxicity was assessed by immobilization and reproduction tests. A mixture toxicity approach was carried out using as starting point the conceptual model of Concentration Addition. The laboratory mixture of both nanomaterials showed that toxicity was dependent on the doses of ZnO and Ag used (immobilization) or presented a synergistic pattern (reproduction). The ZnO/Ag nanostructure toxicity prediction, based on the percentage of individual components, showed an increase in toxicity when compared to the expected (immobilization) and dependent on the concentration used (reproduction). This study demonstrates that the toxicity of the prepared mixture of ZnO and Ag and of the ZnO/Ag nanostructure cannot be predicted based on the toxicity of their components, highlighting the importance of taking into account the interaction between nanomaterials when assessing hazard and risk. Copyright © 2016 Elsevier B.V. All rights reserved.

  11. ZnO deposition on metal substrates: Relating fabrication, morphology, and wettability

    NASA Astrophysics Data System (ADS)

    Beaini, Sara S.; Kronawitter, Coleman X.; Carey, Van P.; Mao, Samuel S.

    2013-05-01

    It is not common practice to deposit thin films on metal substrates, especially copper, which is a common heat exchanger metal and practical engineering material known for its heat transfer properties. While single crystal substrates offer ideal surfaces with uniform structure for compatibility with oxide deposition, metallic surfaces needed for industrial applications exhibit non-idealities that complicate the fabrication of oxide nanostructure arrays. The following study explored different ZnO fabrication techniques to deposit a (super)hydrophobic thin film of ZnO on a metal substrate, specifically copper, in order to explore its feasibility as an enhanced condensing surface. ZnO was selected for its non-toxicity, ability to be made (super)hydrophobic with hierarchical roughness, and its photoinduced hydrophilicity characteristic, which could be utilized to pattern it to have both hydrophobic-hydrophilic regions. We investigated the variation of ZnO's morphology and wetting state, using SEMs and sessile drop contact angle measurements, as a function of different fabrication techniques: sputtering, pulsed laser deposition (PLD), electrodeposition and annealing Zn. We successfully fabricated (super)hydrophobic ZnO on a mirror finish, commercially available copper substrate using the scalable electrodeposition technique. PLD for ZnO deposition did not prove viable, as the ZnO samples on metal substrates were hydrophilic and the process does not lend itself to scalability. The annealed Zn sheets did not exhibit consistent wetting state results.

  12. Efficient room temperature hydrogen sensor based on UV-activated ZnO nano-network

    NASA Astrophysics Data System (ADS)

    Kumar, Mohit; Kumar, Rahul; Rajamani, Saravanan; Ranwa, Sapana; Fanetti, Mattia; Valant, Matjaz; Kumar, Mahesh

    2017-09-01

    Room temperature hydrogen sensors were fabricated from Au embedded ZnO nano-networks using a 30 mW GaN ultraviolet LED. The Au-decorated ZnO nano-networks were deposited on a SiO2/Si substrate by a chemical vapour deposition process. X-ray diffraction (XRD) spectrum analysis revealed a hexagonal wurtzite structure of ZnO and presence of Au. The ZnO nanoparticles were interconnected, forming nano-network structures. Au nanoparticles were uniformly distributed on ZnO surfaces, as confirmed by FESEM imaging. Interdigitated electrodes (IDEs) were fabricated on the ZnO nano-networks using optical lithography. Sensor performances were measured with and without UV illumination, at room temperate, with concentrations of hydrogen varying from 5 ppm to 1%. The sensor response was found to be ˜21.5% under UV illumination and 0% without UV at room temperature for low hydrogen concentration of 5 ppm. The UV-photoactivated mode enhanced the adsorption of photo-induced O- and O2- ions, and the d-band electron transition from the Au nanoparticles to ZnO—which increased the chemisorbed reaction between hydrogen and oxygen. The sensor response was also measured at 150 °C (without UV illumination) and found to be ˜18% at 5 ppm. Energy efficient low cost hydrogen sensors can be designed and fabricated with the combination of GaN UV LEDs and ZnO nanostructures.

  13. Two-dimensional vanadium-doped ZnO nanosheet-based flexible direct current nanogenerator.

    PubMed

    Gupta, Manoj Kumar; Lee, Ju-Hyuck; Lee, Keun Young; Kim, Sang-Woo

    2013-10-22

    Here, we report the synthesis of lead-free single-crystalline two-dimensional (2D) vanadium(V)-doped ZnO nanosheets (NSs) and their application for high-performance flexible direct current (DC) power piezoelectric nanogenerators (NGs). The vertically aligned ZnO nanorods (NRs) converted to NS networks by V doping. Piezoresponse force microscopy studies reveal that vertical V-doped ZnO NS exhibit typical ferroelectricity with clear phase loops, butterfly, and well-defined hysteresis loops with a piezoelectric charge coefficient of up to 4 pm/V, even in 2D nanostructures. From pristine ZnO NR-based NGs, alternating current (AC)-type output current was observed, while from V-doped ZnO NS-based NGs, a DC-type output current density of up to 1.0 μAcm(-2) was surprisingly obtained under the same vertical compressive force. The growth mechanism, ferroelectric behavior, charge inverted phenomena, and high piezoelectric output performance observed from the V-doped ZnO NS are discussed in terms of the formation of an ionic layer of [V(OH)4(-)], permanent electric dipole, and the doping-induced resistive behavior of ZnO NS.

  14. Effect of ZnO facet on ethanol steam reforming over Co/ZnO

    SciTech Connect

    Yu, Ning; Zhang, He; Davidson, Stephen D.

    2016-01-01

    The effects of ZnO facets on ethanol steam reforming (ESR) were investigated over Co/ZnO catalysts synthesized using ZnO with different fractions of (10-10) non-polar facet. Co supported on ZnO with a higher fraction of (10-10) non-polar facet shows higher C-C cleavage activity and higher selectivity to CO2 (lower selectivity to CO) compared with Co supported on ZnO with less (10-10) non-polar facet exposed. The improved ethanol steam reforming performances are attributed to the high fraction of metallic Co stabilized by the ZnO (10-10) non-polar facet, which enhanced C-C cleavage and water-gas-shift (WGS) activities.

  15. Nanostructure investigation of magnetic nanomaterial Ni{sub 0.5}Zn{sub 0.3}Cu{sub 0.2}Fe{sub 2}O{sub 4} synthesized by sol-gel method

    SciTech Connect

    Pransisco, Prengki, E-mail: prengkipransisco@gmail.com; Badan Lingkungan Hidup Derah Kabupaten Empat Lawang South of Sumatera; Shafie, Afza, E-mail: afza@petronas.com.my

    2015-07-22

    Magnetic nanomaterial Ni{sub 0.5}Zn{sub 0.3}Cu{sub 0.2}Fe{sub 2}O{sub 4} was successfully prepared by using sol-gel method. Heat treatment on material is always giving defect on properties of material. This paper investigates the effect of heat treatment on nanostructure of magnetic nanomaterial Ni{sub 0.5}Zn{sub 0.3}Cu{sub 0.2}Fe{sub 2}O{sub 4}. According to thermo gravimetric analysis (TGA) that after 600°C there is no more weight loss detected and it was decided as minimum calcination temperature. Intensity, crystallite size, structure, lattice parameter and d-spacing of the material were investigated by using X-ray diffraction (XRD). High resolution transmission electron microscope (HRTEM) was used to examine nanostructure, nanosize,more » shape and distribution particle of magnetic material Ni{sub 0.5}Zn{sub 0.3}Cu{sub 0.2}Fe{sub 2}O{sub 4} and variable pressure field emission scanning electron microscope (VP-FESEM) was used to investigate the surface morphology and topography of the material. The XRD result shows single-phase cubic spinel structure with average crystallite size in the range of 25.6-95.9 nm, the value of the intensity of the material was increased with increasing temperature, and followed by lattice parameter was increased with increasing calcination temperature, value of d-spacing was relatively decreased with accompanied increasing temperature. From HRTEM result the distribution of particles was tend to be agglomerates with particle size of 7.8-17.68 nm. VP-FESEM result shows that grain size of the material increases with increasing calcination temperature and the surface morphology shows that the material is in hexagonal shape and it was also proved by mapping result which showing the presence each of constituents inside the compound.« less

  16. PREFACE: Nanostructured surfaces

    NASA Astrophysics Data System (ADS)

    Palmer, Richard E.

    2003-10-01

    We can define nanostructured surfaces as well-defined surfaces which contain lateral features of size 1-100 nm. This length range lies well below the micron regime but equally above the Ångstrom regime, which corresponds to the interatomic distances on single-crystal surfaces. This special issue of Journal of Physics: Condensed Matter presents a collection of twelve papers which together address the fabrication, characterization, properties and applications of such nanostructured surfaces. Taken together they represent, in effect, a status report on the rapid progress taking place in this burgeoning area. The first four papers in this special issue have been contributed by members of the European Research Training Network ‘NanoCluster’, which is concerned with the deposition, growth and characterization of nanometre-scale clusters on solid surfaces—prototypical examples of nanoscale surface features. The paper by Vandamme is concerned with the fundamentals of the cluster-surface interaction; the papers by Gonzalo and Moisala address, respectively, the optical and catalytic properties of deposited clusters; and the paper by van Tendeloo reports the application of transmission electron microscopy (TEM) to elucidate the surface structure of spherical particles in a catalyst support. The fifth paper, by Mendes, is also the fruit of a European Research Training Network (‘Micro-Nano’) and is jointly contributed by three research groups; it reviews the creation of nanostructured surface architectures from chemically-synthesized nanoparticles. The next five papers in this special issue are all concerned with the characterization of nanostructured surfaces with scanning tunnelling microscopy (STM) and atomic force microscopy (AFM). The papers by Bolotov, Hamilton and Dunstan demonstrate that the STM can be employed for local electrical measurements as well as imaging, as illustrated by the examples of deposited clusters, model semiconductor structures and real

  17. Fabrication and Characterization of Vertically Aligned ZnO Nanorod Arrays via Inverted Monolayer Colloidal Crystals Mask

    NASA Astrophysics Data System (ADS)

    Chen, Cheng; Ding, Taotao; Qi, Zhiqiang; Zhang, Wei; Zhang, Jun; Xu, Juan; Chen, Jingwen; Dai, Jiangnan; Chen, Changqing

    2018-04-01

    The periodically ordered ZnO nanorod (NR) arrays have been successfully synthesized via a hydrothermal approach on the silicon substrates by templating of the TiO2 ring deriving from the polystyrene (PS) nanosphere monolayer colloidal crystals (MCC). With the inverted MCC mask, sol-gel-derived ZnO seeds could serve as the periodic nucleation positions for the site-specific growth of ZnO NRs. The large-scale patterned arrays of single ZnO NR with good side-orientation can be readily produced. According to the experimental results, the as-integrated ZnO NR arrays showed an excellent crystal quality and optical property, very suitable for optoelectronic applications such as stimulated emitters and ZnO photonic crystal devices.

  18. Effect of deposition parameters on the structural properties of ZnO nanopowders prepared by microwave-assisted hydrothermal synthesis.

    PubMed

    Caglar, Yasemin; Gorgun, Kamuran; Aksoy, Seval

    2015-03-05

    ZnO nanopowders were synthesized via microwave-assisted hydrothermal method at different deposition (microwave irradiation) times and pH values. The effects of pH and deposition (microwave irradiation) time on the crystalline structure and orientation of the ZnO nanopowders have been investigated by X-ray diffraction (XRD) study. XRD observations showed that the crystalline quality of ZnO nanopowders increased with increasing pH value. The crystallite size and texture coefficient values of ZnO nanopowders were calculated. The structural quality of ZnO nanopowder was improved by deposition parameters. Field emission scanning electron microscope (FESEM) was used to analyze the surface morphology of the ZnO nanopowders. Microwave irradiation time and pH value showed a significant effect on the surface morphology. Copyright © 2014 Elsevier B.V. All rights reserved.

  19. Synthesis of ZnO decorated graphene nanocomposite for enhanced photocatalytic properties

    NASA Astrophysics Data System (ADS)

    Gayathri, S.; Jayabal, P.; Kottaisamy, M.; Ramakrishnan, V.

    2014-05-01

    Zinc oxide/Graphene (GZ) composites with different concentrations of ZnO were successfully synthesized through simple chemical precipitation method. The X-ray diffraction pattern and the micro-Raman spectroscopic technique revealed the formation of GZ composite, and the energy dispersive X-ray spectrometry analysis showed the purity of the prepared samples. The ZnO nanoparticles decorated graphene sheets were clearly visible in the field emission scanning electron micrograph. Raman mapping was employed to analyze the homogeneity of the prepared samples. The diffuse-reflectance spectra clearly indicated that the formation of GZ composites promoted the absorption in the visible region also. The photocatalytic activity of ZnO and GZ composites was studied by the photodegradation of Methylene blue dye. The results revealed that the GZ composites exhibited a higher photocatalytic activity than pristine ZnO. Hence, we proposed a simple wet chemical method to synthesize GZ composite and its application on photocatalysis was demonstrated.

  20. Field emission and photoluminescence of ZnO nanocombs

    NASA Astrophysics Data System (ADS)

    Wang, B.; Wu, H. Y.; Zheng, Z. Q.; Yang, Y. H.

    2013-11-01

    Three kinds of new comb-shape nanostructures of ZnO have been grown on single silicon substrates without catalyst-assisted thermal evaporation of Zn and active carbon powders. The morphology and structure of the prepared nanorods are determined on the basis of field-emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM) and x-ray diffraction (XRD). The growth mechanism of the ZnO nanocombs can be explained on the basis of the vapor-solid (VS) processes. In nanocombs 1 and nanocombs 2, the comb teeth grow along [0001] and the comb stem grows along [], while in nanocombs 3, nanoteeth grow along [] and stem grows along [0001]. The photoluminescence and field-emission properties of ZnO nanocombs 1-3 have been investigated. The turn-on electric field of ZnO nanocombs 1-3, which is defined as the field required to producing a current density of 10 μA/cm2, is 9, 7.7 and 7.1 V/μm, respectively. The field-emission performance relies not only on the tip’s radius of curvature and field enhancement factor, but also on the factor evaluating the degree of the screening effect.