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Sample records for ag nanorod substrates

  1. Highly sensitive vertically standing Ag nanorod arrays substrates for surface enhanced fluorescence studies

    NASA Astrophysics Data System (ADS)

    Singh, Dhruv P.; Singh, J. P.

    2013-06-01

    The nanorods length dependence of surface enhanced fluorescence (SEF) has been investigated for Rhodamine 6G films adsorbed onto Ag nanorods array substrates grown by glancing angle deposition technique. It is found that the substrate enhancement efficiency increases with increase in the length (l) of nanorods from 450 nm to 1.7 μm. The silver nanorod arrays substrate with l =1.6 μm exhibited a remarkable enhancement factor (EF) of 72. However, the rate of increment in EF did not remain same. It varies faster for the values of l up to ˜1 μm and after that it increases at comparatively slower rate. The understanding of the effect of nanorods morphology on EF and the identification of high sensitivity SEF substrates is the novelty of this work. These SEF substrates can be used for sensing and trace detection of the fluorescent biological and chemical compounds.

  2. Ag Nanorods Coated with Ultrathin TiO2 Shells as Stable and Recyclable SERS Substrates

    PubMed Central

    Ma, Lingwei; Huang, Yu; Hou, Mengjing; Xie, Zheng; Zhang, Zhengjun

    2015-01-01

    TiO2-coated Ag nanorods (Ag@TiO2 NRs) have been fabricated as multifunctional surface-enhanced Raman scattering (SERS) substrates. Uniform TiO2 shells could sufficiently protect the internal Ag NRs against oxidation and sulfuration, thus the temporal stability of SERS substrates was markedly improved. Meanwhile, due to the synergetic effect between crystalline TiO2 and Ag, the nanocomposites could clean themselves via photocatalytic degradation of the adsorbed molecules under ultraviolet irradiation and water dilution, making the SERS substrates renewable. Such Ag@TiO2 NRs were shown to serve as outstanding SERS sensors featuring high sensitivity, superior stability and recyclability. PMID:26486994

  3. The Silver Nanorod Array SERS Substrates

    NASA Astrophysics Data System (ADS)

    Zhao, Yiping; Liu, Yongjun

    2010-08-01

    The fabrication of large area, uniform and high enhancement substrates for surface enhanced Raman scattering (SERS) based sensing is a bottle-neck for practical applications of SERS. Recently using oblique angle deposition (OAD) method, we have fabricated silver nanorod arrays with SERS enhancement factor >108, and SERS intensity variation <14%. The SERS spectra from those substrates have been demonstrated to be able to distinguish different viruses and virus strains, bacteria, microRNAs, or other chemical and biological molecules. We have performed a detailed characterization on those Ag nanorod substrates. The SERS enhancement factor depends strongly on the nanorod length and the fabrication conditions. For different deposition angle, there is an optimal nanorod length that gives the maximum enhancement. The SERS enhancement seems to directly depend on the reflectivity of the Ag nanorod substrates at the excitation wavelength regardless of the deposition angles and rod length. The SERS performance also depends strongly on the configurations of the excitation laser beam: the incident angle, the polarization, and the reflectance of the underlayer substrates. A simple modified Greenler's model is proposed to qualitatively explain those effects. The possible origin for the high enhancement of the Ag nanorod substrates has been studied by placing the Raman probe molecules on different locations of the substrates, and we have found that the side surfaces of the nanorod arrays contributes more to the SERS enhancement compared to the ends. We propose that this is due to the anisotropic absorbance nature of the Ag nanorod substrates.

  4. Ag nanoparticles-decorated ZnO nanorod array on a mechanical flexible substrate with enhanced optical and antimicrobial properties.

    PubMed

    Chen, Yi; Tse, Wai Hei; Chen, Longyan; Zhang, Jin

    2015-01-01

    Heteronanostructured zinc oxide nanorod (ZnO NR) array are vertically grown on polydimethylsiloxane (PDMS) through a hydrothermal method followed by an in situ deposition of silver nanoparticles (Ag NPs) through a photoreduction process. The Ag-ZnO heterostructured nanorods on PDMS are measured with an average diameter of 160 nm and an average length of 2 μm. ZnO NRs measured by high-resolution transmission electron microscope (HRTEM) shows highly crystalline with a lattice fringe of 0.255 nm, which corresponds to the (0002) planes in ZnO crystal lattice. The average diameter of the Ag NPs in situ deposited on the ZnO NRs is estimated at 22 ± 2 nm. As compared to the bare ZnO NRs, the heterostructured Ag-ZnO nanorod array shows enhanced ultraviolet (UV) absorption at 440 nm, and significant emission in the visible region (λem = 542 nm). In addition, the antimicrobial efficiency of Ag-ZnO heterostructured nanorod array shows obvious improvement as compared to bare ZnO nanorod array. The cytotoxicity of ZnO nanorod array with and without Ag NPs was studied by using 3 T3 mouse fibroblast cell line. No significant toxic effect is imposed on the cells. PMID:25852401

  5. Controlled growth of ZnO nanorods on textured silicon wafer and the application for highly effective and recyclable SERS substrate by decorating Ag nanoparticles

    SciTech Connect

    Tao, Q.; Li, S.; Zhang, Q.Y. Kang, D.W.; Yang, J.S.; Qiu, W.W.; Liu, K.

    2014-06-01

    Highlights: • The growth behavior of ZnO nanorods (NRs) is studied on the textured Si wafer. • A new surface-enhanced Raman scattering (SERS) substrate has been achieved by assembling Ag nanoparticles onto the ZnO NRs. • The SERS substrate exhibits good performance in terms of high sensitivity, good reproducibility and recyclability. - Abstract: Based on the study of growth behavior of ZnO nanorods on the textured Si wafer, a new three-dimensional surface-enhanced Raman scattering substrate has been achieved by assembling Ag nanoparticles onto the ZnO nanorods to form a radial plasmonic nanostructure. It is found that the new substrate exhibits good performance in terms of high sensitivity and good reproducibility for surface-enhanced Raman scattering. The determined enhancement factor is in the order of 10{sup 7} and the Raman spectra exhibit the remarkable consistency with the deviation below 5.0%. Compared to the substrate fabricated with ZnO nanorod array on the flat Si wafer, the new substrates have the higher utility of excitation light. Meanwhile, the new substrate is demonstrated to be recyclable after the irradiation of ultraviolet light.

  6. Large-scale fabrication of polymer/Ag core-shell nanorod array as flexible SERS substrate by combining direct nanoimprint and electroless deposition

    NASA Astrophysics Data System (ADS)

    Liu, Sisi; Xu, Zhimou; Sun, Tangyou; Zhao, Wenning; Wu, Xinghui; Ma, Zhichao; Xu, Haifeng; He, Jian; Chen, Cunhua

    2014-06-01

    We demonstrate a highly sensitive surface-enhanced Raman scattering (SERS) substrate, which consists of Ag nanoparticles (NPs) assembled on the surface of a nanopatterned polymer film. The fabrication route of a polymer/Ag core-shell nanorod (PACSN) array employed a direct nanoimprint technique to create a high-resolution polymer nanorod array. The obtained nanopatterned polymer film was subjected to electroless deposition to form a sea-cucumber-like Ag shell over the surface of the polymer nanorod. The morphology and structures of PACSNs were analyzed by using scanning electron microscopy and X-ray diffraction. The as-synthesized PACSNs exhibited a remarkable SERS activity and Raman signal reproducibility to rhodamine 6G, and a concentration down to 10-12 M can be identified. The effect of electroless deposition time of Ag NPs onto the polymer nanorod surface was investigated. It was found that the electroless deposition time played an important role in SERS activity. Our results revealed that the combination of direct nanoimprint and electroless deposition provided a convenient and cost-effective way for large-scale fabrication of reliable SERS substrates without the requirement of expensive instruments.

  7. A novel flexible C2H2 gas sensor based on Ag-ZnO nanorods on PI/PTFE substrate

    NASA Astrophysics Data System (ADS)

    Uddin, A. S. M. Iftekhar; Chung, Gwiy-Sang

    2016-02-01

    In this work a novel flexible acetylene (C2H2) gas sensor based on Ag nanoparticles decorated vertical ZnO nanorods (Ag-ZnO NRs) on PI/PTFE substrate has been investigated. The grown structure was synthesized through a simple, rapid, and low-temperature hydrothermal-RF magnetron sputtering method. The successful immobilization of Ag nanoparticles (NPs) onto the surface of ZnO nanorods contributed large effective surface area and facilitated the charge transfer process. The as-fabricated sensor exhibited enhanced C2H2 sensing performances at low temperature (200°C) including a broad detection range (3 - 1000 ppm), and short recovery time (39 sec). Mechanical robustness and device flexibility were investigated at different curvature angle (0 - 90°) and several times bending-relaxing process (0 - 5 × 105 times). The sensor exhibited stable response magnitude with a negligible drift of ~ 2.1% for a maximum bending angle of 90o and a response drop of 8% after 5 × 104 bending/relaxing processes. The superior sensing features along with outstanding flexibility to extreme bending stress indicate the sensor a promising candidate for the development of practical flexible C2H2 gas sensors.

  8. Enhanced thermal stability of Ag nanorods through capping

    SciTech Connect

    Bachenheimer, Lou; Elliott, Paul; Stagon, Stephen; Huang, Hanchen

    2014-11-24

    Ag nanorods may serve as sensors in the detection of trace amounts of chemical agents, even single molecules, through surface enhanced Raman spectroscopy (SERS). However, thermal coarsening of Ag nanorods near room temperature limits their applications. This letter proposes the use of a thin oxide capping layer to enhance the thermal stability of Ag nanorods beyond 100 °C. Using electron microscopy characterization and SERS tests, the authors show that the proposed method is effective in stabilizing both morphology and sensitivity of Ag nanorods. The results of this work extend the applicability of Ag nanorods as chemical sensors to higher temperatures.

  9. Focused-ion-beam-fabricated Au nanorods coupled with Ag nanoparticles used as surface-enhanced Raman scattering-active substrate for analyzing trace melamine constituents in solution.

    PubMed

    Sivashanmugan, Kundan; Liao, Jiunn-Der; Liu, Bernard Haochih; Yao, Chih-Kai

    2013-10-24

    A well-ordered Au-nanorod array with a controlled tip ring diameter (Au_NRsd) was fabricated using the focused ion beam method. Au_NRsd was then coupled with Ag nanoparticles (Ag NPs) to bridge the gaps among Au nanorods. The effect of surface-enhanced Raman scattering (SERS) on Au_NRsd and Ag NPs/Au_NRsd was particularly verified using crystal violet (CV) as the molecular probe. Raman intensity obtained from a characteristic peak of CV on Au_NRsd was estimated by an enhancement factor of ≈10(7) in magnitude, which increased ≈10(12) in magnitude for that on Ag NPs/Au_NRsd. A highly SERS-active Ag NPs/Au_NRsd was furthermore applied for the detection of melamine (MEL) at very low concentrations. Raman-active peaks of MEL (10(-3) to 10(-12)M) in water or milk solution upon Au_NRsd or Ag NPs/Au_NRsd were well distinguished. The peaks at 680 and 702 cm(-1) for MEL molecules were found suitable to be used as the index for sensing low-concentration MEL in a varied solution, while that at 1051 cm(-1) was practical to interpret MEL molecules in water or milk solution bonded with Au (i.e., Au_NRsd) or Ag (i.e., Ag NPs/Au_NRsd) surface. At the interface of Ag NPs/Au_NRsd and MEL molecules in milk solution, a laser-induced electromagnetic field or hotspot effect was produced and competent to sense low-concentration MEL molecules interacting with Ag and Au surfaces. Accordingly, Ag NPs/Au_NRsd is very promising to be used as a fast and sensitive tool for screening MEL in complex matrices such as adulteration in e.g., food and pharmaceutical products. PMID:24120168

  10. Aligned silver nanorod arrays as substrates for surface-enhanced infrared absorption spectroscopy.

    PubMed

    Leverette, C L; Jacobs, S A; Shanmukh, S; Chaney, S B; Dluhy, R A; Zhao, Y-P

    2006-08-01

    Preferentially aligned silver nanorod arrays prepared by oblique angle vapor deposition were evaluated as substrates for surface-enhanced infrared absorption (SEIRA) spectroscopy. These nanorod arrays have an irregular surface lattice and are composed of tilted, cylindrically shaped nanorods that have an average length of 868 nm +/- 95 nm and an average diameter of 99 nm +/- 29 nm. The overall enhancement factor for chemisorbed organic films of para-nitrobenzoic acid (PNBA) deposited onto the Ag nanorod arrays analyzed by external reflection SEIRA was calculated to be 31 +/- 9 compared to infrared reflection-absorption spectroscopy (IRRAS) obtained from a 500 nm Ag film substrate. This enhancement is attributed to the unique optical properties of the nanorod arrays as well as the increased surface area provided by the nanorod substrate. SEIRA reflection-absorbance intensity was observed with both p- and s-polarized incident radiation with angles of incidence ranging from 25 degrees to 80 degrees . The largest intensity was achieved with p-polarization and incident angles larger than 75 degrees . Polarization-dependent ultraviolet/visible/near-infrared (UV/Vis/NIR) spectra of the nanorod arrays demonstrate that the red-shifted surface plasmon peaks of the elongated nanorods may be partially responsible for the observed SEIRA response. The SEIRA detection limit for the Ag nanorod arrays was estimated to be 0.08 ng/cm(2). Surface-enhanced Raman scattering (SERS) and SEIRA analysis of chemisorbed PNBA utilizing the same nanorod substrate is demonstrated. PMID:16925927

  11. Control of Separation and Diameter of Ag Nanorods through Self-organized Seeds.

    PubMed

    Elliott, Paul R; Stagon, Stephen P; Huang, Hanchen

    2015-01-01

    This paper proposes a mechanism of controlling the diameter and separation of metallic nanorods from physical vapor deposition through self-organized seeds and experimentally demonstrates the feasibility using Ag as the prototype metal, In as the seed, and Si the substrate. Being non-wetting on Si substrates, deposited In atoms self-organize into islands. Subsequently deposited Ag atoms attach to In islands, rather than to Si substrates, due to preferential bonding and geometrical shadowing. The experimental results show that self-organized In seeds of 5 nm nominal thickness give rise to the best separation and the smallest diameter of Ag nanorods. PMID:26585104

  12. Control of Separation and Diameter of Ag Nanorods through Self-organized Seeds

    PubMed Central

    Elliott, Paul R.; Stagon, Stephen P.; Huang, Hanchen

    2015-01-01

    This paper proposes a mechanism of controlling the diameter and separation of metallic nanorods from physical vapor deposition through self-organized seeds and experimentally demonstrates the feasibility using Ag as the prototype metal, In as the seed, and Si the substrate. Being non-wetting on Si substrates, deposited In atoms self-organize into islands. Subsequently deposited Ag atoms attach to In islands, rather than to Si substrates, due to preferential bonding and geometrical shadowing. The experimental results show that self-organized In seeds of 5 nm nominal thickness give rise to the best separation and the smallest diameter of Ag nanorods. PMID:26585104

  13. Aligned Silver Nanorod Array as SERS Substrates for Viral Sensing

    NASA Astrophysics Data System (ADS)

    Zhao, Yiping; Shanmukh, Saratchandra; Chaney, Stephen B.; Jones, Les; Dluhy, Richard A.; Tripp, Ralph A.

    2006-03-01

    The aligned silver nanorod array substrates prepared by the oblique angle deposition method are capable of providing extremely high enhancement factors (˜10^9) at near-infrared wavelengths (785 nm) for a standard reporter molecule 1,2 trans-(bis)pyridyl-ethene (BPE). The enhancement factor depends strongly on the length of the Ag nanorods, the substrate coating, as well as the polarization of the excitation laser beam. With the current optimum structure, we demonstrate that the detection limit for BPE can be lower than 0.1 fM. The applicability of this substrate to the detection of bioagents has been investigated by looking several viruses, such as Adenovirus, HIV, Rhinovirus and Respiratory Syncytial Virus (RSV), at low quantities (˜0.5uL). Different viruses have different fingerprint Raman spectrum. The detection of virus presented in infected cells has also been demonstrated.

  14. Component conversion from pure Au nanorods to multiblock Ag-Au-Ag nanorods assisted by Pt nanoframe templates.

    PubMed

    Lee, Sangji; Jang, Hee-Jeong; Jang, Ho Young; Kim, Seong Kyu; Park, Sungho

    2016-07-14

    We developed a new method for synthesizing multiblock Ag-Au-Ag nanorods using Pt nanoframes that had been deposited on the edges of Au nanorod seeds. As a function of Au etching time, the length of the Au nanorod decreased symmetrically starting from the two ends, leading to the formation of empty inner space at the ends. Subsequent reduction of Ag ions could be selectively performed in the inner space confined by Pt nanoframes and the resulting Ag-Au-Ag nanorods exhibited characteristic LSPR modes originating from each block component (in a transverse direction) and SPR coupling (in a longitudinal direction). The high quality of the resulting multiblock nanorods enabled observation of the longitudinal quadrupole mode that was induced by Ag-Au SPR coupling in a long axis. The mode exhibited high sensitivity in accordance with the change in the surrounding media, demonstrating great potential for sensor applications. PMID:27315144

  15. Component conversion from pure Au nanorods to multiblock Ag-Au-Ag nanorods assisted by Pt nanoframe templates

    NASA Astrophysics Data System (ADS)

    Lee, Sangji; Jang, Hee-Jeong; Jang, Ho Young; Kim, Seong Kyu; Park, Sungho

    2016-06-01

    We developed a new method for synthesizing multiblock Ag-Au-Ag nanorods using Pt nanoframes that had been deposited on the edges of Au nanorod seeds. As a function of Au etching time, the length of the Au nanorod decreased symmetrically starting from the two ends, leading to the formation of empty inner space at the ends. Subsequent reduction of Ag ions could be selectively performed in the inner space confined by Pt nanoframes and the resulting Ag-Au-Ag nanorods exhibited characteristic LSPR modes originating from each block component (in a transverse direction) and SPR coupling (in a longitudinal direction). The high quality of the resulting multiblock nanorods enabled observation of the longitudinal quadrupole mode that was induced by Ag-Au SPR coupling in a long axis. The mode exhibited high sensitivity in accordance with the change in the surrounding media, demonstrating great potential for sensor applications.We developed a new method for synthesizing multiblock Ag-Au-Ag nanorods using Pt nanoframes that had been deposited on the edges of Au nanorod seeds. As a function of Au etching time, the length of the Au nanorod decreased symmetrically starting from the two ends, leading to the formation of empty inner space at the ends. Subsequent reduction of Ag ions could be selectively performed in the inner space confined by Pt nanoframes and the resulting Ag-Au-Ag nanorods exhibited characteristic LSPR modes originating from each block component (in a transverse direction) and SPR coupling (in a longitudinal direction). The high quality of the resulting multiblock nanorods enabled observation of the longitudinal quadrupole mode that was induced by Ag-Au SPR coupling in a long axis. The mode exhibited high sensitivity in accordance with the change in the surrounding media, demonstrating great potential for sensor applications. Electronic supplementary information (ESI) available. See DOI: 10.1039/c6nr03484e

  16. Ag-nanoparticles-decorated NiO-nanoflakes grafted Ni-nanorod arrays stuck out of porous AAO as effective SERS substrates.

    PubMed

    Zhou, Qitao; Meng, Guowen; Huang, Qing; Zhu, Chuhong; Tang, Haibin; Qian, Yiwu; Chen, Bin; Chen, Bensong

    2014-02-28

    NiO-nanoflakes (NiO-NFs) grafted Ni-nanorod (Ni-NR) arrays stuck out of the porous anodic aluminum oxide (AAO) template are achieved by a combinatorial process of AAO-confined electrodeposition of Ni-NRs, selectively etching part of the AAO template to expose the Ni-NRs, wet-etching the exposed Ni-NRs in ammonia to obtain Ni(OH)2-NFs grafted onto the cone-shaped Ni-NRs, and annealing to transform Ni(OH)2-NFs in situ into NiO-NFs. By top-view sputtering, Ag-nanoparticles (Ag-NPs) are decorated on each NiO-NFs grafted Ni-NR (denoted as NiO-NFs@Ni-NR). The resultant Ag-NPs-decorated NiO-NFs@Ni-NR (denoted as Ag-NPs@NiO-NFs@Ni-NR) arrays exhibit not only strong surface-enhanced Raman scattering (SERS) activity but also reproducible SERS-signals over the whole array. It is demonstrated that the strong SERS-activity is mainly ascribed to the high density of sub-10 nm gaps (hot spots) between the neighboring Ag-NPs, the semiconducting NiO-NFs induced chemical enhancement effect, and the lightning rod effect of the cone-shaped Ni-NRs. The three-level hierarchical nanostructure arrays stuck out of the AAO template can be utilized to probe polychlorinated biphenyls (PCBs, a kind of global environmental hazard) with a concentration as low as 5 × 10(-6) M, showing promising potential in SERS-based rapid detection of organic environmental pollutants. PMID:24419246

  17. Enhancement of antibacterial properties of Ag nanorods by electric field

    NASA Astrophysics Data System (ADS)

    Akhavan, Omid; Ghaderi, Elham

    2009-01-01

    The effect of an electric field on the antibacterial activity of columnar aligned silver nanorods was investigated. Silver nanorods with a polygonal cross section, a width of 20-60 nm and a length of 260-550 nm, were grown on a titanium interlayer by applying an electric field perpendicular to the surface of a Ag/Ti/Si(100) thin film during its heat treatment at 700 °C in an Ar+H2 environment. The optical absorption spectrum of the silver nanorods exhibited two peaks at wavelengths of 350 and 395 nm corresponding to the main surface plasmon resonance bands of the one-dimensional silver nanostructures. It was found that the silver nanorods with an fcc structure were bounded mainly by {100} facets. The antibacterial activity of the silver nanorods against Escherichia coli bacteria was evaluated at various electric fields applied in the direction of the nanorods without any electrical connection between the nanorods and the capacitor plates producing the electric field. Increasing the electric field from 0 to 50 V cm-1 resulted in an exponential increase in the relative rate of reduction of the bacteria from 3.9×10-2 to 10.5×10-2 min-1. This indicates that the antibacterial activity of silver nanorods can be enhanced by applying an electric field, for application in medical and food-preserving fields.

  18. Kinetics-controlled growth of bimetallic RhAg on Au nanorods and their catalytic properties

    NASA Astrophysics Data System (ADS)

    Ye, Wei; Guo, Xia; Xie, Fang; Zhu, Rui; Zhao, Qing; Yang, Jian

    2014-03-01

    Controlled growth of hybrid metallic nanocomposites for a desirable structure in a combination of selected components is highly important for their applications. Herein, the controllable growth of RhAg on the gold nanorods is achieved from the dumbbell-like RhAg-tipped nanorods to the brushy RhAg-coated nanorods, or the rod-like Au@Ag-Rh nanorattles. These different growth modes of RhAg on the gold nanorods are correlated with the reducing kinetics of RhCl3 and AgNO3. In view of the promising catalytic properties of Rh, the gold nanorods modified by RhAg in different structures are examined as catalysts for the oxidation of o-phenylenediamine. It is found that brushy RhAg-coated nanorods present a higher catalytic efficiency than dumbbell-like RhAg-tipped nanorods and rod-like Au@Ag-Rh nanorattles. These results would benefit the overgrowth control on the one-dimensional metallic nanorods and the rational design of new generation heterogeneous catalysts and optical devices.Controlled growth of hybrid metallic nanocomposites for a desirable structure in a combination of selected components is highly important for their applications. Herein, the controllable growth of RhAg on the gold nanorods is achieved from the dumbbell-like RhAg-tipped nanorods to the brushy RhAg-coated nanorods, or the rod-like Au@Ag-Rh nanorattles. These different growth modes of RhAg on the gold nanorods are correlated with the reducing kinetics of RhCl3 and AgNO3. In view of the promising catalytic properties of Rh, the gold nanorods modified by RhAg in different structures are examined as catalysts for the oxidation of o-phenylenediamine. It is found that brushy RhAg-coated nanorods present a higher catalytic efficiency than dumbbell-like RhAg-tipped nanorods and rod-like Au@Ag-Rh nanorattles. These results would benefit the overgrowth control on the one-dimensional metallic nanorods and the rational design of new generation heterogeneous catalysts and optical devices. Electronic

  19. Laser stimulated electrooptics in the Ag-ZnO nanorods

    NASA Astrophysics Data System (ADS)

    Tan, Sin Tee; AlZayed, N. S.; Lakshminarayana, G.; Naumar, F.; Umar, A. A.; Oyama, M.; Myronchuk, G.; Kityk, I. V.

    2014-07-01

    In the present work, we have discovered a photoinduced linear electrooptics in ZnO nanorods which were fabricated by simply varying the content of the growth solution. It was established that by varying the growth solution concentration one can vary the surface density of the ZnO nanorod arrays growth on the surface. The lowest ZnO content produces the lowest surface density in the nanorods. The photoinduced linear electrooptics was studied using the He-Ne laser at wavelength 1150 nm and was stimulated by 7 ns nitrogen laser at 371 nm. The nonlinear dependence of the Ag nanoparticle (NP) concentration was found and it was significantly higher than that for the pure ZnO NP. Principal role of the Ag NP on the observed effects was discussed.

  20. Growth of Au@Ag core-shell pentatwinned nanorods: tuning the end facets.

    PubMed

    Zhang, Weiqing; Goh, Hao Ying Johnny; Firdoz, Shaik; Lu, Xianmao

    2013-09-16

    Au@Ag core-shell nanorods with tunable end facets are obtained by coating Au bipyramids (BPs) with Ag. The resultant nanorods exhibit a pentatwinned crystal structure with tips terminated with either {110} or {111} facets. The control over the end facets is achieved by varying the capping agents and tuning the reduction rate of Ag. Specifically, when Ag is reduced slowly, Au@Ag nanorods with flat {110} end facets are formed with cetyltrimethylammonium bromide (CTAB) as the capping agent. If CTAB is replaced with cetyltrimethylammonium chloride (CTAC), Au@Ag nanorods with tips terminated with {111} facets are obtained. However, at a high Ag reduction rate, dumbbell-shaped Au@Ag nanorods are formed, with either CTAB or CTAC as the capping agent. The morphological evolution of the nanorods in each case is closely followed and a growth mechanism is proposed. PMID:23934938

  1. Template-based synthesis of Ni nanorods on silicon substrate

    NASA Astrophysics Data System (ADS)

    Jin, Xiaoyun; Hu, Yan; Wang, Yao; Shen, Ruiqi; Ye, Yinghua; Wu, Lizhi; Wang, Shouxu

    2012-01-01

    Free-standing nickel (Ni) nanorods were successfully prepared by pulsed electrodeposition using porous alumina membrane (PAM) on titanium (Ti) pre-coated silicon (Si) substrate. Initially, Si substrate was coated with subsequent layers of Ti (∼200 nm) and Al (∼600 nm) by sputtering process. The PAM/Ti/Si structure was fabricated by a two-step anodization in 0.3 M oxalic acid under a constant voltage of 40 V, and then used to grow Ni nanorods by pulsed electrodeposition. Finally, an Al layer was deposited on the Ni nanorods. The relationship between the pore-widening time and the pore diameter of the PAM on Si was also investigated. Field emission scanning electron microscopy (FESEM) was employed to observe the morphology of PAM, Ni nanorods and Al/Ni heterostructure. Transmission electron microscopy (TEM) and X-ray diffraction (XRD) were used to study the morphological and structural properties of Ni nanorods, respectively. Also, the compositional properties of the samples were characterized by energy dispersive X-ray spectra (EDS). The pore diameter and the pore length of the PAM were approximately 54.2 ± 12.2 nm and 800 nm, respectively. The Ni nanorods stand perpendicularly on the substrate, whose diameter and length were similar to the PAM. The Ni nanorods give an XRD pattern of face-centered cubic crystal structure. Ni nanorods with deposited a layer of Al have the potential application of a heat source or energetic material in the silicon-based micro-electromechanical systems (MEMS) compatible device.

  2. Recyclable three-dimensional Ag nanoparticle-decorated TiO2 nanorod arrays for surface-enhanced Raman scattering.

    PubMed

    Fang, Hui; Zhang, Chang Xing; Liu, Luo; Zhao, Yong Mei; Xu, Hai Jun

    2015-02-15

    Multifunctional Ag nanoparticle-decorated TiO2 nanorod arrays were prepared by two simple processes. TiO2 nanorod arrays were first fabricated by the hydrothermal route and then Ag nanoparticles were decorated on the nanorods by the chemical reduction impregnation method. Three-dimensional Ag/TiO2 arrays were used as an active substrate for surface-enhanced Raman scattering (SERS). The results show that the detection limit for rhodamine 6G (R6G) was as low as 10(-7)M and the Raman enhancement factor was as large as 10(5). After calibrating the Raman peak intensities of R6G, it could be quantitatively detected. More importantly, the photocatalytic activity of TiO2 provides a self-cleaning capability to the SERS substrate, which can be recycled and used to degrade many Ag surface adsorbates such as R6G, methyl orange, Congo red, and methylene blue after exposure to visible light. The absorbed small molecules can all be rapidly and completely removed from the SERS substrate, which has been successfully reused four times without a decrease in accuracy or sensitivity. Our results reveal that the unique recyclable property not only paves a new way to solve the single-use problem of traditional SERS substrates but also provides more SERS platforms for multiple detections of other organic molecular species. PMID:25282397

  3. Label free detection of DNA on Au/ZnO/Ag hybrid structure based SERS substrate

    NASA Astrophysics Data System (ADS)

    Pal, Anil Kumar; Mohan, D. Bharathi

    2016-04-01

    Au/ZnO/Ag based SERS substrate was fabricated for the label free detection of DNA of Escherichia Coli bacteria. The SERS substrate was fabricated by growing ZnO nanorod arrays on thermally evaporated ultrathin Ag film of 5 nm thickness using hydrothermal process. Non-spherical like Au nanoparticles were decorated on ZnO nanorod arrays by sputtering technique with sputtering time of 45 sec. The surface of Au/ZnO/Ag was observed to be nearly superhydrophobic exhibiting the contact angle of 144 °. A low volume (5 µl) of aqueous solution of DNA of laboratory strain Escherichia Coli with very low concentration was adsorbed on fabricated SERS substrate by drop casting. The SERS detection of DNA molecules was achieved up to lower concentration of 10-8 M due to strong local electric field enhancement at the nanometer gap among Au nanoparticles and superhydrophobic nature of Au/ZnO/Ag surface.

  4. Metal enhanced fluorescence improved protein and DNA detection by zigzag Ag nanorod arrays.

    PubMed

    Ji, Xiaofan; Xiao, Chenyu; Lau, Wai-Fung; Li, Jianping; Fu, Junxue

    2016-08-15

    As metal nano-arrays show great potential on metal enhanced fluorescence (MEF) than random nanostructures, MEF of Ag zigzag nanorod (ZNR) arrays made by oblique angle deposition has been studied for biomolecule-protein interaction and DNA hybridization. By changing the folding number and the deposition substrate temperature, a 14-fold enhancement factor (EF) is obtained for biotin-neutravidin detection. The optimal folding number is decided as Z=7, owing to the high scattering intensity of Ag ZNRs. The substrate temperature T=25°C and 0°C slightly alters the morphology of Ag ZNRs but has no big difference in EF. Further, Ag ZNRs deposited on a layer of Ag film have been introduced to the DNA hybridization and a significant signal enhancement has been observed through the fluorescence microscope. Through a detailed quantitative EF analysis, which excludes the enhancing effect from the increased surface area of ZNRs and only considers the contribution of MEF, an EF of 28 is achieved for the hybridization of two single-stranded oligonucleotides with 33 bases. Furthermore, a limit of detection is determined as 0.01pM. We believe that the Ag ZNR arrays can serve as a universal and sensitive bio-detection platform. PMID:27088369

  5. Substrate-bound growth of Au-Pd diblock nanowire and hybrid nanorod-plate

    NASA Astrophysics Data System (ADS)

    He, Jiating; Wang, Yawen; Fan, Zhanxi; Lam, Zhenhui; Zhang, Hua; Liu, Bin; Chen, Hongyu

    2015-04-01

    We expand the scope of the previously developed Active Surface Growth mode for growing substrate-bound ultrathin Pd (d = 4 nm) and Ag nanowires (d = 30 nm) in aqueous solution under ambient conditions. Using Au nanorods as the seeds, selective growth at the contact line between the rod and the substrate eventually leads to an attached Pd nanoplate. The unique growth mode also allows sequential growth of different materials via a single seed, giving substrate-bound Au-Pd diblock nanowires. The new abilities to use seed shape to pre-define the active sites and to apply sequential growth open windows for new pathways to hybrid nanostructures.We expand the scope of the previously developed Active Surface Growth mode for growing substrate-bound ultrathin Pd (d = 4 nm) and Ag nanowires (d = 30 nm) in aqueous solution under ambient conditions. Using Au nanorods as the seeds, selective growth at the contact line between the rod and the substrate eventually leads to an attached Pd nanoplate. The unique growth mode also allows sequential growth of different materials via a single seed, giving substrate-bound Au-Pd diblock nanowires. The new abilities to use seed shape to pre-define the active sites and to apply sequential growth open windows for new pathways to hybrid nanostructures. Electronic supplementary information (ESI) available: Supporting TEM and SEM images of control experiments with different reaction conditions and another type of diblock nanowires. See DOI: 10.1039/c5nr00361j

  6. Si/ZnO nanorods/Ag/AZO structures as promising photovoltaic plasmonic cells

    SciTech Connect

    Placzek-Popko, E. Gwozdz, K.; Gumienny, Z.; Zielony, E.; Jacak, W.; Pietruszka, R.; Witkowski, B. S.; Wachnicki, Ł.; Gieraltowska, S.; Chang, Liann-Be

    2015-05-21

    The test structures for photovoltaic (PV) applications based on zinc oxide nanorods (NRs) that were grown using a low-temperature hydrothermal method on p-type silicon substrates (100) covered with Ag nanoparticles (NPs) were studied. The NPs of three different diameters, i.e., 5–10 nm, 20-30 nm, and 50–60 nm, were deposited using a sputtering method. The morphology and crystallinity of the structures were confirmed by scanning electron microscopy and Raman spectroscopy. It was found that the nanorods have a hexagonal wurtzite structure. An analysis of the Raman and photoluminescence spectra permitted the identification of the surface modes at 476 cm{sup −1} and 561 cm{sup −1}. The presence of these modes is evidence of nanorods oriented along the wurtzite c-axis. The NRs with Ag NPs were covered with a ZnO:Al (AZO) layer that was grown using the low-temperature atomic layer deposition technique. The AZO layer served as a transparent ohmic contact to the ZnO nanorods. The applicability of the AZO layer for this purpose and the influence of the Ag nanoparticles on the effectiveness of light acquisition by such prepared PV cells were checked by reflectance and transmittance measurements of the AZO/glass and AZO/NPs/glass reference structures. Based on these studies, the high-energy transmittance edge was assigned to the ZnO energy gap, although it is blueshifted with respect to the bulk ZnO energy gap because of Al doping. It was also shown that the most optimal PV performance is obtained from a structure containing Ag nanoparticles with a diameter of 20–30 nm. This result is confirmed by the current-voltage measurements performed with 1-sun illumination. The structures show a plasmonic effect within the short wavelength range: the PV response for the structure with Ag nanoparticles is twice that of the structure without the nanoparticles. However, the influence of the Ag nanoparticle diameters on the plasmonic effect is ambiguous.

  7. Si/ZnO nanorods/Ag/AZO structures as promising photovoltaic plasmonic cells

    NASA Astrophysics Data System (ADS)

    Placzek-Popko, E.; Gwozdz, K.; Gumienny, Z.; Zielony, E.; Pietruszka, R.; Witkowski, B. S.; Wachnicki, Ł.; Gieraltowska, S.; Godlewski, M.; Jacak, W.; Chang, Liann-Be

    2015-05-01

    The test structures for photovoltaic (PV) applications based on zinc oxide nanorods (NRs) that were grown using a low-temperature hydrothermal method on p-type silicon substrates (100) covered with Ag nanoparticles (NPs) were studied. The NPs of three different diameters, i.e., 5-10 nm, 20-30 nm, and 50-60 nm, were deposited using a sputtering method. The morphology and crystallinity of the structures were confirmed by scanning electron microscopy and Raman spectroscopy. It was found that the nanorods have a hexagonal wurtzite structure. An analysis of the Raman and photoluminescence spectra permitted the identification of the surface modes at 476 cm-1 and 561 cm-1. The presence of these modes is evidence of nanorods oriented along the wurtzite c-axis. The NRs with Ag NPs were covered with a ZnO:Al (AZO) layer that was grown using the low-temperature atomic layer deposition technique. The AZO layer served as a transparent ohmic contact to the ZnO nanorods. The applicability of the AZO layer for this purpose and the influence of the Ag nanoparticles on the effectiveness of light acquisition by such prepared PV cells were checked by reflectance and transmittance measurements of the AZO/glass and AZO/NPs/glass reference structures. Based on these studies, the high-energy transmittance edge was assigned to the ZnO energy gap, although it is blueshifted with respect to the bulk ZnO energy gap because of Al doping. It was also shown that the most optimal PV performance is obtained from a structure containing Ag nanoparticles with a diameter of 20-30 nm. This result is confirmed by the current-voltage measurements performed with 1-sun illumination. The structures show a plasmonic effect within the short wavelength range: the PV response for the structure with Ag nanoparticles is twice that of the structure without the nanoparticles. However, the influence of the Ag nanoparticle diameters on the plasmonic effect is ambiguous.

  8. Morphological and SERS Properties of Silver Nanorod Array Films Fabricated by Oblique Thermal Evaporation at Various Substrate Temperatures.

    PubMed

    Oh, Myoung-Kyu; Shin, Yong-Seok; Lee, Chang-Lyoul; De, Ranjit; Kang, Hoonsoo; Yu, Nan Ei; Kim, Bok Hyeon; Kim, Joon Heon; Yang, Jin-Kyu

    2015-12-01

    Aligned silver nanorod (AgNR) array films were fabricated by oblique thermal evaporation. The substrate temperature during evaporation was varied from 10 to 100 °C using a home-built water cooling system. Deposition angle and substrate temperature were found to be the most important parameters for the morphology of fabricated films. Especially, it was found that there exists a critical temperature at ~90 °C for the formation of the AgNR array. The highest enhancement factor of the surface-enhanced Raman scattering (SERS), observed in the Ag films coated with benzenethiol monolayer, was ~6 × 10(7). Hot spots, excited in narrow gaps between nanorods, were attributed to the huge enhancement factor by our finite-difference time-domain (FDTD) simulation reflecting the real morphology. PMID:26061442

  9. SPR sensitivity of silver nanorods in CsBr-Ag nanocomposite thin films

    NASA Astrophysics Data System (ADS)

    Lovkush; Ravikant, Chhaya; Arun, P.; Kumar, Kuldeep

    2016-07-01

    We have investigated the optical and morphological properties of CsBr-Ag complex thin films deposited by thermal evaporation on glass substrate. By varying the thickness of the film with fixed mass ratio of cesium bromide and silver, we observed a broad absorption peak in the visible region from 350 to 450 nm corresponding to the transverse and longitudinal surface plasmon resonance (SPR) mode. Red shift is observed, with varying film thickness, in SPR peak position corresponding to longitudinal mode with no significant change in transverse mode due to variation in the aspect ratio of the silver nano crystalline grains. Scanning electron microscope and EDX revealed the formation of silver nanorods in film samples. Such, stable and tunable CsBr-Ag films can be used in optical filters.

  10. MICROWAVE-ASSISTED SHAPE CONTROLLED BULK SYNTHESIS OF AG AND FE NANORODS IN POLY (ETHYLENE GLYCOL) SOLUTIONS

    EPA Science Inventory

    Bulk syntheses of silver (Ag) and iron (Fe) nanorods using poly (ethylene glycol), PEG, under microwave irradiation (MW) conditions are reported. Favorable conditions to make Ag nanorods were established and can be extended to make Fe nanorods with uniform size and shape. The nan...

  11. Synthesis of Ag{sub 2}S nanorods by biomimetic method in the lysozyme matrix

    SciTech Connect

    Qin, Dezhi Zhang, Li; He, Guoxu; Zhang, Qiuxia

    2013-09-01

    Graphical abstract: - Highlights: • Firstly, Ag{sub 2}S nanorods were synthesized by biomimetic method in the lysozyme solutions. • The study of the interaction between Ag{sup +} and the lysozyme. • Discussion of possible formation mechanism of Ag{sub 2}S nanorods. • The synthesis process of lyso-conjugated Ag{sub 2}S nanocrystals is facile, effective and environment friendly. - Abstract: Ag{sub 2}S nanorods were successfully synthesized by biomimetic route in the lysozyme solution at physiological temperature and atmospheric pressure. The transmission electron microscopy (TEM) images revealed that the prepared nanorods are uniform and monodisperse with homogeneous size about 50 nm in diameter and 150 nm in length. The optical property of Ag{sub 2}S nanocrystals was studied by the ultraviolet–visible (UV–vis) and photoluminescence (PL) spectroscopy, the results show that the products exhibit well-defined emission at 471 nm and 496 nm excited by 292 nm. The interaction of Ag{sup +}/Ag{sub 2}S with the lysozyme was investigated through Fourier transform infrared (FT-IR) spectroscopy, which shows that the cooperation effect of the lysozyme and Ag{sup +} could be responsible for the formation of as obtained Ag{sub 2}S nanorods.

  12. EXAFS Studies of Bimetallic Ag-Pt and Ag-Pd Nanorods

    SciTech Connect

    Lahiri, D.; Chattopadhyay, S.; Bunker, B.A.; Doudna, C.M.; Bertino, M.F.; Blum, F.; Tokuhiro, A.; Terry, J.

    2008-10-30

    Nanoparticles of Ag-Pt and Ag-Pd with high aspect ratios were synthesized using a radiolysis method. Gamma rays at dose rates below 0.5 kGy/h were used for irradiation. The nanoparticles were characterized by transmission electron microscopy (TEM), optical absorption spectroscopy and x-ray Absorption Fine Structure (XAFS) spectroscopy. Bright field micrographs show that Ag-Pt nanowires are composed of large particles with diameters ranging from 20-30 nm and joined by filaments of diameter between 2-5 nm. The Ag-Pd nanowires have diameters of 20-25 nm and lengths of 1.5 {micro}m. For XAFS measurements, the Pt L3 edge (11.564 keV), Ag K-edge (25.514 keV) and Pd K-edge (24.350 keV) were excited to determine the local structure around the respective atoms in the cluster. The Ag-Pt particles were found to possess a distinct core-shell structure with Pt in the core surrounded by Ag shell, with no indication of alloy formation. However, nanorods of Ag-Pd have formed an alloy for all the alloy compositions.

  13. Synthesis of defect-rich, (001) faceted-ZnO nanorod on a FTO substrate as efficient photocatalysts for dehydrogenation of isopropanol to acetone

    NASA Astrophysics Data System (ADS)

    Tan, Sin Tee; Umar, Akrajas Ali; Salleh, Muhamad Mat

    2016-06-01

    Highly oriented ZnO nanorod was successfully synthesised on Ag nanoseed coated FTO substrate via a microwave hydrolysis approach. It was found that the morphology and the optical properties of the ZnO nanorod are strongly influenced by the power of the microwave irradiation used during the growth process. The aspect ratio of the nanorods changed from high to low with the increasing of microwave power. It was also found that the optical band gap of the ZnO nanorod red shifted with the increasing of the microwave power, reflecting an excellent tune ability of the optical properties of ZnO nanorods. The photocatalytic activity of these unique nanorod was evaluated by a dehydrogenation process of isopropanol to acetone in the presence of ZnO nanorod. It was found that the ZnO nanorod exhibited an excellent catalytic performance by showing an ability to accelerate the production of 0.031 mol L-1 of acetone within only 35 min or 0.9 mmol L-1 min-1 from isopropyl alcohol dehydrogenation. It was almost no conversion from isopropyl alcohol when ZnO nanorods was absence during the reaction. In this report, a detailed mechanism of ZnO nanorod formation and the relationship between morphology and optical energy band gap are described.

  14. Fabrication of Ag-Nanorods/Polyimide Nanocomposites and Their Thermal, Mechanical, Electrical, and Dielectric Properties.

    PubMed

    Weng, Ling; Yan, Li-Wen; Li, Hong-Xia; Liu, Li-Zhu

    2016-02-01

    Silver nanorods/polyimide (Ag-NRs/PI) nanocomposites with high conductivity (An order of magnitude higher than pure PI), frequency-independent dielectric permittivity (3.8-4.2) and low dielectric loss (<0.05) were prepared by an in-situ polymerization process. Ag-nanorods with a mean width of approximately 300 nm and an average length over 8 microm were synthesized in the presence of polyvinylpyrrolidone (PVP) and NaCl by polyol process. SEM images showed that metallic Ag-nanorods were well dispersed in PI matrix. The structure of Ag-NRs was not destroyed or changed in nanocomposite films and the order of PI molecular chains was maintained as well. The orientation of the Ag-NRs in the PI matrix improved the mechanical properties of nanocomposite films. TGA results showed that the thermal property of nanocomposite films was almost as good as pure PI. PMID:27433637

  15. Controllable synthesis porous Ag2CO3 nanorods for efficient photocatalysis

    NASA Astrophysics Data System (ADS)

    Guo, Shenghui; Bao, Jianxing; Hu, Tu; Zhang, Libo; Yang, Li; Peng, Jinhui; Jiang, Caiyi

    2015-04-01

    The novel porous Ag2CO3 nanorods were facilely synthesized via a one-pot aqueous solution reaction at room temperature. The crystalline phase and size distribution of the nanorods were determined by X-ray diffraction (XRD) and scanning electron microscopy (SEM), respectively. In addition, the porous feature of nanorods was confirmed by transmission electron microscopy (TEM) and nitrogen adsorption-desorption. The morphology and size of the Ag2CO3 crystal can be regulated via the choice of dispersing agents and adding approaches of reactants. Photocatalytic results show that the porous Ag2CO3 nanorods exhibit excellent photodegradation of rhodamine B (RhB) under visible-light irradiation, particularly the photoactivity performance and stability can be further improved in the presence of sodium bicarbonate (NaHCO3). It is indicated that NaHCO3 can prevent effectively the photocorrosion and promote the probability of electron-hole separation.

  16. Facile synthesis of S–Ag nanocomposites and Ag2S short nanorods by the interaction of sulfur with AgNO3 in PEG400

    NASA Astrophysics Data System (ADS)

    Zhang, Yan-Li; Xie, Xin-Yuan; Liang, Ming; Xie, Shu-Ming; Chen, Jie-Mei; Zheng, Wen-Jie

    2016-06-01

    A facile, eco-friendly and inexpensive method to prepare Ag2S short nanorods and S–Ag nanocomposites using sublimed sulfur, AgNO3, PVP and PEG400 was studied. According to x-ray diffraction and scanning electron microscopy of the Ag2S, the products are highly crystalline and pure Ag2S nanorods with diameters of 70–160 nm and lengths of 200–360 nm. X-ray diffraction of the S–Ag nanocomposites shows that we obtained cubic Ag and S nanoparticles. Transmission electron microscopy shows that the molar ratio of PVP to Ag+ plays an important role in controlling the size and morphology of the S–Ag nanocomposites. When the molar ratio of PVP to Ag+ was 10:1, smaller sizes, better dispersibility and narrower distribution of S–Ag nanocomposites with diameters of 10–40 nm were obtained. The formation mechanism of the S–Ag nanocomposites was studied by designing a series of experiments using ultraviolet–visible measurement, and it was found that S nanoparticles are produced first and act as seed crystals; then Ag+ becomes Ag nanocrystals on the surfaces of the S nanoparticles by the reduction of PVP. PEG400 acts as a catalyzer, accelerating the reaction rate, and protects the S–Ag nanocomposites from reacting to produce Ag2S. The antimicrobial experiments show that the S–Ag nanocomposites have greater antimicrobial activity on Staphylococcus aureus, Aspergillus niger and blue mold than Ag nanoparticles.

  17. Facile formation of Ag{sub 2}WO{sub 4}/AgX (X = Cl, Br, I) hybrid nanorods with enhanced visible-light-driven photoelectrochemical properties

    SciTech Connect

    Li, Jingjing; Yu, Caiyun; Zheng, Changcheng; Etogo, Atangana; Xie, Yunlong; Zhong, Yijun; Hu, Yong

    2015-01-15

    Highlights: • Ag{sub 2}WO{sub 4}/AgX hybrid nanorods were prepared by a facile in-situ anion exchange reaction. • Ag{sub 2}WO{sub 4} nanorods and different X{sup −} ions were reacted in water at room temperature. • The hybrids possess significantly enhanced photoelectrochemical properties. • Ag{sub 2}WO{sub 4}/AgBr hybrids exhibit the highest photocatalytic activity among three samples. • The active species tests were also investigated to confirm photocatalytic mechanism. - Abstract: In this work, we demonstrated a general strategy for the preparation of a series of uniform Ag{sub 2}WO{sub 4}/AgX (X = Cl, Br, I) hybrid nanorods by a facile in-situ anion exchange reaction occurring at room temperature between pregrown Ag{sub 2}WO{sub 4} nanorods and different X{sup −} ions in water. Compared with Ag{sub 2}WO{sub 4} nanorods, further investigation has revealed that the as-prepared hybrid nanorods possess significantly enhanced photocurrent response and photocatalytic activity in degrading methyl orange (MO) under visible-light irradiation. In particular, the Ag{sub 2}WO{sub 4}/AgBr hybrid nanorods exhibit the highest photocatalytic activity among the three kinds of samples. The active species tests indicate that superoxide anion radicals and photogenerated holes are responsible for the enhanced photocatalytic performance.

  18. Laser treatment of Ag@ZnO nanorods as long-life-span SERS surfaces.

    PubMed

    Macias-Montero, Manuel; Peláez, Ramón J; Rico, Victor J; Saghi, Zineb; Midgley, Paul; Afonso, Carmen N; González-Elipe, Agustín R; Borras, Ana

    2015-02-01

    UV nanosecond laser pulses have been used to produce a unique surface nanostructuration of Ag@ZnO supported nanorods (NRs). The NRs were fabricated by plasma enhanced chemical vapor deposition (PECVD) at low temperature applying a silver layer as promoter. The irradiation of these structures with single nanosecond pulses of an ArF laser produces the melting and reshaping of the end of the NRs that aggregate in the form of bundles terminated by melted ZnO spherical particles. Well-defined silver nanoparticles (NPs), formed by phase separation at the surface of these melted ZnO particles, give rise to a broad plasmonic response consistent with their anisotropic shape. Surface enhanced Raman scattering (SERS) in the as-prepared Ag@ZnO NRs arrays was proved by using a Rhodamine 6G (Rh6G) chromophore as standard analyte. The surface modifications induced by laser treatment improve the stability of this system as SERS substrate while preserving its activity. PMID:25575182

  19. Synthesis and characterization of Si/ZnO coaxial nanorod heterostructure on (100) Si substrate

    NASA Astrophysics Data System (ADS)

    Dong Cho, Hak; Young Cho, Hoon; Wook Kwak, Dong; Won Kang, Tae; Taek Yoon, Im

    2016-03-01

    One-dimensional ZnO nanorods were grown vertically on a (100) Si substrate using a vapor phase transport method. Following the fabrication of ZnO nanorods, Si layers were deposited by rapid thermal chemical vapor deposition (RTCVD) directly on the ZnO nanorod/Si (100) substrate. Field emission scanning electron microscopy revealed that a Si/ZnO nanorod coaxial heterostructure were synthesized vertically oriented along the (002) plane on a Si substrate. X-ray diffraction, Energy dispersive X-ray and Raman spectroscopy revealed that the ZnO nanorods were single crystals with a hexagonal structure, and grew with a c-axis orientation perpendicular to the Si substrate, whereas the Si layer was poly-silicon with cubic structure. These results demonstrated the Si/ZnO nanorod coaxial heterostructure were synthesized successfully on a (100) Si substrate and the ZnO nanorod enables the synthesis of a vertically grown well-aligned Si/ZnO coaxial nanorod heterostructure.

  20. Synthesis of highly efficient antibacterial agent Ag doped ZnO nanorods: Structural, Raman and optical properties

    SciTech Connect

    Jan, Tariq; Iqbal, Javed; Ismail, Muhammad; Mahmood, Arshad

    2014-04-21

    Here, synthesis, structural, morphological, Raman, optical properties and antibacterial activity of undoped and Ag doped ZnO nanorods by chemical co-precipitation technique have been reported. Structural analysis has revealed that Ag doping cannot deteriorate the structure of ZnO and wurtzite phase is maintained. Lattice constants are found to be decreased with the Ag doping. Fourier transform infrared and Raman spectroscopy also confirm the X-ray diffraction results. Scanning electron microscopy results have demonstrated the formation of ZnO nanorods with average diameter and length of 96 nm and 700 nm, respectively. Raman spectroscopy results suggest that the Ag doping enhances the number of defects in ZnO crystal. It has been found from optical study that Ag doping results in positional shift of band edge absorption peak. This is attributed to the successful incorporation of Ag dopant into ZnO host matrix. The antibacterial activity of prepared nanorods has been determined by two different methods and compared to that of undoped ZnO nanorods. Ag doped ZnO nanorods exhibit excellent antibacterial activity as compared to that of undoped ZnO nanorods. This excellent antibacterial activity may be attributed to the presence of oxygen vacancies and Zn{sup 2+} interstitial defects. Our preliminary findings suggest that Ag doped ZnO nanorods can be used externally to control the spreading of infections related with tested bacterial strains.

  1. Facile synthesis of S-Ag nanocomposites and Ag2S short nanorods by the interaction of sulfur with AgNO3 in PEG400.

    PubMed

    Zhang, Yan-Li; Xie, Xin-Yuan; Liang, Ming; Xie, Shu-Ming; Chen, Jie-Mei; Zheng, Wen-Jie

    2016-06-01

    A facile, eco-friendly and inexpensive method to prepare Ag2S short nanorods and S-Ag nanocomposites using sublimed sulfur, AgNO3, PVP and PEG400 was studied. According to x-ray diffraction and scanning electron microscopy of the Ag2S, the products are highly crystalline and pure Ag2S nanorods with diameters of 70-160 nm and lengths of 200-360 nm. X-ray diffraction of the S-Ag nanocomposites shows that we obtained cubic Ag and S nanoparticles. Transmission electron microscopy shows that the molar ratio of PVP to Ag(+) plays an important role in controlling the size and morphology of the S-Ag nanocomposites. When the molar ratio of PVP to Ag(+) was 10:1, smaller sizes, better dispersibility and narrower distribution of S-Ag nanocomposites with diameters of 10-40 nm were obtained. The formation mechanism of the S-Ag nanocomposites was studied by designing a series of experiments using ultraviolet-visible measurement, and it was found that S nanoparticles are produced first and act as seed crystals; then Ag(+) becomes Ag nanocrystals on the surfaces of the S nanoparticles by the reduction of PVP. PEG400 acts as a catalyzer, accelerating the reaction rate, and protects the S-Ag nanocomposites from reacting to produce Ag2S. The antimicrobial experiments show that the S-Ag nanocomposites have greater antimicrobial activity on Staphylococcus aureus, Aspergillus niger and blue mold than Ag nanoparticles. PMID:27109417

  2. Ultrasensitive SERS detection of trinitrotoluene through capillarity-constructed reversible hot spots based on ZnO-Ag nanorod hybrids

    NASA Astrophysics Data System (ADS)

    He, Xuan; Wang, Hui; Li, Zhongbo; Chen, Dong; Liu, Jiahui; Zhang, Qi

    2015-04-01

    A simple and efficient self-approach strategy was used to apply ultrasensitivity and self-revive ZnO-Ag hybrid surface-enhanced Raman scattering (SERS) sensors for the highly sensitive and selective detection of explosive TNT in both solution and vapour conditions. The good ultrasensitive sensing performance is a result of the abundant Raman hot spots, which were spontaneously formed in a reversible way by the self-approaching of flexible ZnO-Ag hybrid nanorods driven by the capillary force of solvent evaporation. Moreover, the enhancement effect was repeatedly renewed by the reconstruction of molecular bridges, which could selectively detect TNT with a lower limit of 4 × 10-14 M. In addition, TNT vapor was also tested under this sensor, whereby once the ZnO-Ag NRs hybrid substrate was dipped in TNT, this substrate could detect the existence of TNT even in 5 detection cycles via a capillarity-constructed reversible hot spots approach. Compared with other pure Ag-based SERS sensors, this ZnO-Ag hybrid SERS sensor could rapidly self-revive SERS-activity by simple UV light irradiation and could retain stable SERS sensitivity for one month when used for TNT detection. This stable and ultrasensitive SERS substrate demonstrates a new route to eliminate the oxidized inactive problem of traditional Ag-based SERS substrates and suggests promising use in the applications of such hybrids as real-time online sensors for explosives detection.A simple and efficient self-approach strategy was used to apply ultrasensitivity and self-revive ZnO-Ag hybrid surface-enhanced Raman scattering (SERS) sensors for the highly sensitive and selective detection of explosive TNT in both solution and vapour conditions. The good ultrasensitive sensing performance is a result of the abundant Raman hot spots, which were spontaneously formed in a reversible way by the self-approaching of flexible ZnO-Ag hybrid nanorods driven by the capillary force of solvent evaporation. Moreover, the enhancement

  3. ZnO/Ag composite nanorod arrays for surface-plasmon-enhanced emission study

    SciTech Connect

    Pal, Anil Kumar E-mail: d.bharathimohan@gmail.com; Mohan, D. Bharathi E-mail: d.bharathimohan@gmail.com

    2014-04-24

    The surface plasmon resonance enhanced emission through coupling of surface plasmons and exciton band energies is studied in hybrid ZnO/Ag nanostructure. The catalytic growth of ZnO nanorods is controlled in seed mediated growth by altering size distribution of Ag nanoislands. X-ray diffraction shows a predominant (002) crystal plane confirming the preferential growth of ZnO nanorods on as-deposited Ag. Increase of surface roughness in Ag film by post deposition annealing process enhances the light emission due to momentum matching between surface plasmons and excitons as well as a red shift of 32 meV occurs due to multi phonon and phonon-exciton interaction.

  4. A DNA-Assembled Fe3O4@Ag Nanorod in Silica Matrix for Cholesterol Biosensing

    NASA Astrophysics Data System (ADS)

    Satvekar, R. K.; Tiwari, A. P.; Rohiwal, S. S.; Tiwale, B. M.; Pawar, S. H.

    2015-12-01

    A novel nanocomposite having DNA-assembled Fe3O4@Ag nanorods in silica matrix has been proposed for fabrication of bienzymatic cholesterol nanobiosensor. Cholesterol oxidase and horseradish peroxidase have been co-encapsulated in Silica/Fe3O4@Ag-DNA nanocomposite deposited on the indium tin oxide electrode. Cyclic voltammetry was employed for the electrochemical behavior of proposed biosensor and used to estimate cholesterol with a linear range of 5-195 mg/dL.

  5. Arginine-assisted immobilization of silver nanoparticles on ZnO nanorods: an enhanced and reusable antibacterial substrate without human cell cytotoxicity

    NASA Astrophysics Data System (ADS)

    Agnihotri, Shekhar; Bajaj, Geetika; Mukherji, Suparna; Mukherji, Soumyo

    2015-04-01

    Silver-based hybrid nanomaterials are gaining interest as potential alternatives for conventional antimicrobial agents. Herein, we present a simple, facile and eco-friendly approach for the deposition of silver nanoparticles (AgNPs) on ZnO nanorods, which act as a nanoreactor for in situ synthesis and as an immobilizing template in the presence of arginine. The presence of arginine enhanced the stability of ZnO deposition on the glass substrate by hindering the dissolution of zinc under alkaline conditions. Various Ag/ZnO hybrid nanorod (HNR) samples were screened to obtain a high amount of silver immobilization on the ZnO substrate. Ag/ZnO HNRs displayed potent antibacterial ability and could achieve 100% kill for both Escherichia coli and Bacillus subtilis strains under various test conditions. The hybrid material mediated its dual mode of antibacterial action through direct contact-killing and release of silver ions/nanoparticles and showed superior bactericidal performance compared to pure ZnO nanorods and colloidal AgNPs. No significant decline in antibacterial efficacy was observed even after the same substrate was repeatedly reused multiple times. Interestingly, the amount of Ag and Zn release was much below their maximal limit in drinking water, thus preventing potential health hazards. Immobilized AgNPs showed no cytotoxic effects on the human hepatocarcinoma cell line (HepG2). Moreover, treating cells with the antibacterial substrate for 24 hours did not lead to significant generation of reactive oxygen species (ROS). The good biocompatibility and bactericidal efficacy would thus make it feasible to utilize this immobilization strategy for preparing new-generation antibacterial coatings.Silver-based hybrid nanomaterials are gaining interest as potential alternatives for conventional antimicrobial agents. Herein, we present a simple, facile and eco-friendly approach for the deposition of silver nanoparticles (AgNPs) on ZnO nanorods, which act as a

  6. Numerical investigation of radiative properties and surface plasmon resonance of silver nanorod dimers on a substrate

    NASA Astrophysics Data System (ADS)

    An, Wei; Zhu, Tong; Zhu, QunZhi

    2014-01-01

    When the distance between two silver nanoparticles is small enough, interparticle surface plasmon coupling has a great impact on their radiative properties. It is becoming a promising technique to use in the sensing and imaging. A model based on finite difference time domain method is developed to investigate the effect of the assembled parameters on the radiative properties and the field-enhancement effect of silver nanorod dimer. The numerical results indicate that the radiative properties of silver nanorod dimer are very sensitive to the assembled angle and the polarization orientation of incident wave. There is great difference on the intensity and location of field-enhancement effect for the cases of different assembled angle and polarization. The most intensive field-enhancement effect occurs in the middle of two nanorods when two nanorods is assembled head to head and the polarization orientation parallels to the length axis of nanorods. Moreover, compared with the single nanorod, the wavelength of extinction peak of dimer has a red-shift, and the intensity of field-enhancement effect on the dimer is more intensive than that of single particle. With the increasing of particle length, extinction cross-section of silver nanorod dimer rises, while extinction efficiency and scattering efficiency firstly increase then drop down gradually. In addition, the extinction peaks of silver nanorod dimer on the substrate are smaller than that without the substrate, and their extinction peaks has a red-shift compared with that without the substrate.

  7. Maximizing the photo catalytic and photo response properties of multimodal plasmonic Ag/WO(3-x) heterostructure nanorods by variation of the Ag size.

    PubMed

    Ghosh, Sirshendu; Saha, Manas; Paul, Sumana; De, S K

    2015-11-21

    High quality nearly monodisperse colloidal WO3-x nanorods with an aspect ratio ∼18 were synthesized using the thermal decomposition technique. The effects of a capping agent and an activating agent on the nanorod aspect ratio have been studied. Excess carrier concentration due to large oxygen vacancy and smaller width of the nanorods compared to the Bohr exciton radius gives rise to an increase of the band gap. Shape anisotropy in nanorods results in two plasmonic absorbance bands at about 890 nm and 5900 nm corresponding to short axis and long axis plasmon modes. The short axis mode reveals an excellent plasmonic sensitivity of ∼345 nm per refractive index. A plasmonic photocatalysis process based on WO3-x nanorods has been developed to synthesize Ag/WO3-x heterostructures consisting of multiple Ag dots with ∼2 nm size, randomly decorated on the surface of the WO3-x nanorods. Long time irradiation leads to an increase in the size (5 nm) of Ag nanocrystals concomitant with decrease in the number of Ag nanocrystals attached per WO3-x nanorod. Plasmonic photocatalysis followed by thermal annealing produces only one Ag nanocrystal of size ∼10 nm on each WO3-x nanorod. Red shifting and broadening of plasmon bands of Ag nanocrystals and WO3-x nanorods confirm the formation of heterostructures between the metal and semiconductor. Detailed transmission electron micrograph analysis indicates the epitaxial growth of Ag nanocrystals onto WO3-x nanorods. A high photocurrent gain of about 4000 is observed for Ag (10 nm)/WO3-x heterostructures. The photodegradation rate for Rhodamine-B and methylene blue is maximum for Ag (10 nm)/WO3-x heterostructures due to efficient electron transfer from WO3-x nanorods to Ag nanocrystals. Metal plasmon-semiconductor exciton coupling, prominent plasmon absorbance of metal nanoparticles, and formation of an epitaxial interface are found to be the important factors to achieve the maximum photocatalytic activity and fabrication of a

  8. Microfluidic-based metal enhanced fluorescence for capillary electrophoresis by Ag nanorod arrays

    NASA Astrophysics Data System (ADS)

    Xiao, Chenyu; Cao, Zhen; Deng, Junhong; Huang, Zhifeng; Xu, Zheng; Fu, Junxue; Yobas, Levent

    2014-06-01

    As metal nanorods show much higher metal enhanced fluorescence (MEF) than metal nanospheres, microfluidic-based MEF is first explored with Ag nanorod (ND) arrays made by oblique angle deposition. By measuring the fluorescein isothiocyanate (FITC) solution sandwiched between the Ag NDs and a piece of cover slip, the enhancement factors (EFs) are found as 3.7 ± 0.64 and 6.74 ± 2.04, for a solution thickness at 20.8 μm and 10 μm, respectively. Because of the strong plasmonic coupling between the adjacent Ag NDs, only the emission of the fluorophores present in the three-dimensional NDs array gets enhanced. Thus, the corresponding effective enhancement factors (EEFs) are revealed to be relatively close, 259 ± 92 and 340 ± 102, respectively. To demonstrate the application of MEF in microfluidic systems, a multilayer of SiO2 NDs/Ag NDs is integrated with a capillary electrophoresis device. At a microchannel depth of 10 μm, an enhancement of 6.5 fold is obtained for amino acids separation detection. These results are very encouraging and open the possibility of MEF applications for the Ag ND arrays decorated microchannels. With the miniaturization of microfluidic devices, microfluidic-based MEF by Ag ND arrays will likely find more applications with further enhancement.

  9. Pinhole Effect on the Melting Behavior of Ag@Al2O3 SERS Substrates.

    PubMed

    Ma, Lingwei; Huang, Yu; Hou, Mengjing; Li, Jianghao; Zhang, Zhengjun

    2016-12-01

    High-temperature surface-enhanced Raman scattering (SERS) sensing is significant for practical detections, and pinhole-containing (PC) metal@oxide structures possessing both enhanced thermal stability and superior SERS sensitivity are served as promising SERS sensors at extreme sensing conditions. Through tuning the Al2O3 precursors' exposure time during atomic layer deposition (ALD), Al2O3 shells with different amount of pinholes were covered over Ag nanorods (Ag NRs). By virtue of these unique PC Ag@Al2O3 nanostructures, herein we provide an excellent platform to investigate the relationship between the pinhole rate of Al2O3 shells and the melting behavior, high-temperature SERS performances of these core-shell nanostructures. Pinhole effect on the melting procedures of PC Ag@Al2O3 substrates was characterized in situ via their reflectivity variations during heating, and the specific melting point was quantitatively estimated. It is found that the melting point of PC Ag@Al2O3 raised along with the decrement of pinhole rate, and substrates with less pinholes exhibited better thermal stability but sacrificed SERS efficiency. This work achieved highly reliable and precise control of the pinholes over Al2O3 shells, offering sensitive SERS substrates with intensified thermal stability and superior SERS performances at extreme sensing conditions. PMID:27033846

  10. Pinhole Effect on the Melting Behavior of Ag@Al2O3 SERS Substrates

    NASA Astrophysics Data System (ADS)

    Ma, Lingwei; Huang, Yu; Hou, Mengjing; Li, Jianghao; Zhang, Zhengjun

    2016-03-01

    High-temperature surface-enhanced Raman scattering (SERS) sensing is significant for practical detections, and pinhole-containing (PC) metal@oxide structures possessing both enhanced thermal stability and superior SERS sensitivity are served as promising SERS sensors at extreme sensing conditions. Through tuning the Al2O3 precursors' exposure time during atomic layer deposition (ALD), Al2O3 shells with different amount of pinholes were covered over Ag nanorods (Ag NRs). By virtue of these unique PC Ag@Al2O3 nanostructures, herein we provide an excellent platform to investigate the relationship between the pinhole rate of Al2O3 shells and the melting behavior, high-temperature SERS performances of these core-shell nanostructures. Pinhole effect on the melting procedures of PC Ag@Al2O3 substrates was characterized in situ via their reflectivity variations during heating, and the specific melting point was quantitatively estimated. It is found that the melting point of PC Ag@Al2O3 raised along with the decrement of pinhole rate, and substrates with less pinholes exhibited better thermal stability but sacrificed SERS efficiency. This work achieved highly reliable and precise control of the pinholes over Al2O3 shells, offering sensitive SERS substrates with intensified thermal stability and superior SERS performances at extreme sensing conditions.

  11. Buckling and mechanical instability of ZnO nanorods grown on different substrates under uniaxial compression.

    PubMed

    Riaz, M; Fulati, A; Zhao, Q X; Nur, O; Willander, M; Klason, P

    2008-10-15

    Mechanical instability and buckling characterization of vertically aligned single-crystal ZnO nanorods grown on different substrates including Si, SiC and sapphire (α-Al(2)O(3)) was done quantitatively by the nanoindentation technique. The nanorods were grown on these substrates by the vapor-liquid-solid (VLS) method. The critical load for the ZnO nanorods grown on the Si, SiC and Al(2)O(3) substrates was found to be 188, 205 and 130 µN, respectively. These observed critical loads were for nanorods with 280 nm diameters and 900 nm length using Si as a substrate, while the corresponding values were 330 nm, 3300 nm, and 780 nm, 3000 nm in the case of SiC and Al(2)O(3) substrates, respectively. The corresponding buckling energies calculated from the force displacement curves were 8.46 × 10(-12), 1.158 × 10(-11) and 1.092 × 10(-11) J, respectively. Based on the Euler model for long nanorods and the J B Johnson model (which is an extension of the Euler model) for intermediate nanorods, the modulus of elasticity of a single rod was calculated for each sample. Finally, the critical buckling stress and strain were also calculated for all samples. We found that the buckling characteristic is strongly dependent on the quality, lattice mismatch and adhesion of the nanorods with the substrate. PMID:21832659

  12. Maximizing the photo catalytic and photo response properties of multimodal plasmonic Ag/WO3-x heterostructure nanorods by variation of the Ag size

    NASA Astrophysics Data System (ADS)

    Ghosh, Sirshendu; Saha, Manas; Paul, Sumana; de, S. K.

    2015-10-01

    High quality nearly monodisperse colloidal WO3-x nanorods with an aspect ratio ~18 were synthesized using the thermal decomposition technique. The effects of a capping agent and an activating agent on the nanorod aspect ratio have been studied. Excess carrier concentration due to large oxygen vacancy and smaller width of the nanorods compared to the Bohr exciton radius gives rise to an increase of the band gap. Shape anisotropy in nanorods results in two plasmonic absorbance bands at about 890 nm and 5900 nm corresponding to short axis and long axis plasmon modes. The short axis mode reveals an excellent plasmonic sensitivity of ~345 nm per refractive index. A plasmonic photocatalysis process based on WO3-x nanorods has been developed to synthesize Ag/WO3-x heterostructures consisting of multiple Ag dots with ~2 nm size, randomly decorated on the surface of the WO3-x nanorods. Long time irradiation leads to an increase in the size (5 nm) of Ag nanocrystals concomitant with decrease in the number of Ag nanocrystals attached per WO3-x nanorod. Plasmonic photocatalysis followed by thermal annealing produces only one Ag nanocrystal of size ~10 nm on each WO3-x nanorod. Red shifting and broadening of plasmon bands of Ag nanocrystals and WO3-x nanorods confirm the formation of heterostructures between the metal and semiconductor. Detailed transmission electron micrograph analysis indicates the epitaxial growth of Ag nanocrystals onto WO3-x nanorods. A high photocurrent gain of about 4000 is observed for Ag (10 nm)/WO3-x heterostructures. The photodegradation rate for Rhodamine-B and methylene blue is maximum for Ag (10 nm)/WO3-x heterostructures due to efficient electron transfer from WO3-x nanorods to Ag nanocrystals. Metal plasmon-semiconductor exciton coupling, prominent plasmon absorbance of metal nanoparticles, and formation of an epitaxial interface are found to be the important factors to achieve the maximum photocatalytic activity and fabrication of a high speed

  13. Maximizing the photo catalytic and photo response properties of multimodal plasmonic Ag/WO3-x heterostructure nanorods by variation of the Ag size

    NASA Astrophysics Data System (ADS)

    Ghosh, Sirshendu; Saha, Manas; Paul, Sumana; de, S. K.

    2015-10-01

    High quality nearly monodisperse colloidal WO3-x nanorods with an aspect ratio ~18 were synthesized using the thermal decomposition technique. The effects of a capping agent and an activating agent on the nanorod aspect ratio have been studied. Excess carrier concentration due to large oxygen vacancy and smaller width of the nanorods compared to the Bohr exciton radius gives rise to an increase of the band gap. Shape anisotropy in nanorods results in two plasmonic absorbance bands at about 890 nm and 5900 nm corresponding to short axis and long axis plasmon modes. The short axis mode reveals an excellent plasmonic sensitivity of ~345 nm per refractive index. A plasmonic photocatalysis process based on WO3-x nanorods has been developed to synthesize Ag/WO3-x heterostructures consisting of multiple Ag dots with ~2 nm size, randomly decorated on the surface of the WO3-x nanorods. Long time irradiation leads to an increase in the size (5 nm) of Ag nanocrystals concomitant with decrease in the number of Ag nanocrystals attached per WO3-x nanorod. Plasmonic photocatalysis followed by thermal annealing produces only one Ag nanocrystal of size ~10 nm on each WO3-x nanorod. Red shifting and broadening of plasmon bands of Ag nanocrystals and WO3-x nanorods confirm the formation of heterostructures between the metal and semiconductor. Detailed transmission electron micrograph analysis indicates the epitaxial growth of Ag nanocrystals onto WO3-x nanorods. A high photocurrent gain of about 4000 is observed for Ag (10 nm)/WO3-x heterostructures. The photodegradation rate for Rhodamine-B and methylene blue is maximum for Ag (10 nm)/WO3-x heterostructures due to efficient electron transfer from WO3-x nanorods to Ag nanocrystals. Metal plasmon-semiconductor exciton coupling, prominent plasmon absorbance of metal nanoparticles, and formation of an epitaxial interface are found to be the important factors to achieve the maximum photocatalytic activity and fabrication of a high speed

  14. Ag(I)-triggered one-pot synthesis of Ag nanoparticles onto natural nanorods as a multifunctional nanocomposite for efficient catalysis and adsorption.

    PubMed

    Tian, Guangyan; Wang, Wenbo; Mu, Bin; Kang, Yuru; Wang, Aiqin

    2016-07-01

    A multifunctional palygorskite/polyaniline/Ag nanoparticles (PAL/PANI/AgNPs) nanocomposite was prepared at room temperature using a simple one-pot in-situ polymerization reaction of aniline monomers triggered by Ag(I) on the surface of natural PAL nanorods. Ag(I) served as both the oxidant and the precursor of the AgNPs, which initiated the polymerization of aniline monomers on PAL nanorods while simultaneously being reduced to form Ag(0) nanoparticles (AgNPs). The in-situ formed AgNPs were evenly distributed on the surface of the PAL nanorods because the interfacial effect of PAL prevents their aggregation. The density and size of the AgNPs and the catalytic activity of the nanocomposites could be controlled by altering the molar ratio of aniline to Ag(I). The performance evaluation revealed that the nanocomposites could be used as highly active catalysts, which rapidly catalyzed the reduction of 4-nitrophenol (4-NP) within 2min and Congo red (CR) within 10min. The nanocomposites are also an effective adsorbent for H2PO4(-) able to remove 99.40% of H2PO4(-) (only 61.77% for raw PAL) from a solution with an initial concentration of 50mg/L. This multifunctional nanocomposite synthesized by a simple one-pot approach is a promising material for environmental applications. PMID:27054770

  15. Synthesis and characterization of Cu-doped ZnO nanorods chemically grown on flexible substrate

    NASA Astrophysics Data System (ADS)

    Shabannia, R.

    2016-08-01

    Vertically aligned undoped and Cu-doped ZnO nanorods array were successfully grown on flexible substrate by chemical bath deposition method at a low 0074emperature. The fabricated materials were characterized using X-ray diffraction (XRD), field-emission scanning electron microscopy (FESEM), energy dispersive X-ray spectroscopy (EDX) and photoluminescence (PL) spectroscopy. XRD analysis showed that Cu doping improves the crystallinity of the fabricated ZnO nanorods. The mean diameter and bending of the ZnO nanorods increase with an increase of Cu doping, but the density of Cu-doped ZnO nanorods almost unchanged. Room temperature PL measurement displayed increased intensity in UV peak and decreased visible peak after Cu doping.

  16. Growth of Well-Aligned InN Nanorods on Amorphous Glass Substrates

    NASA Astrophysics Data System (ADS)

    Li, Huijie; Zhao, Guijuan; Wei, Hongyuan; Wang, Lianshan; Chen, Zhen; Yang, Shaoyan

    2016-05-01

    The growth of well-aligned nanorods on amorphous substrates can pave the way to fabricate large-scale and low-cost devices. In this work, we successfully prepared vertically well-aligned c-axis InN nanorods on amorphous glass substrate by metal-organic chemical vapor deposition. The products formed directly on bare glass are randomly oriented without preferential growth direction. By inserting a GaN/Ti interlayer, the nanowire alignment can be greatly improved as indicated by scanning electron microscopy and X-ray diffraction.

  17. Growth of Well-Aligned InN Nanorods on Amorphous Glass Substrates.

    PubMed

    Li, Huijie; Zhao, Guijuan; Wei, Hongyuan; Wang, Lianshan; Chen, Zhen; Yang, Shaoyan

    2016-12-01

    The growth of well-aligned nanorods on amorphous substrates can pave the way to fabricate large-scale and low-cost devices. In this work, we successfully prepared vertically well-aligned c-axis InN nanorods on amorphous glass substrate by metal-organic chemical vapor deposition. The products formed directly on bare glass are randomly oriented without preferential growth direction. By inserting a GaN/Ti interlayer, the nanowire alignment can be greatly improved as indicated by scanning electron microscopy and X-ray diffraction. PMID:27229517

  18. Solvothermal Preparation of ZnO Nanorods as Anode Material for Improved Cycle Life Zn/AgO Batteries

    PubMed Central

    Ullah, Shafiq; Ahmed, Fiaz; Badshah, Amin; Ali Altaf, Ataf; Raza, Ramsha; Lal, Bhajan; Hussain, Rizwan

    2013-01-01

    Nano materials with high surface area increase the kinetics and extent of the redox reactions, thus resulting in high power and energy densities. In this study high surface area zinc oxide nanorods have been synthesized by surfactant free ethylene glycol assisted solvothermal method. The nanorods thus prepared have diameters in the submicron range (300∼500 nm) with high aspect ratio. They have uniform geometry and well aligned direction. These nanorods are characterized by XRD, SEM, Specific Surface Area Analysis, solubility in alkaline medium, EDX analysis and galvanostatic charge/discharge studies in Zn/AgO batteries. The prepared zinc oxide nanorods have low solubility in alkaline medium with higher structural stability, which imparts the improved cycle life stability to Zn/AgO cells. PMID:24146807

  19. Surface-enhanced Raman scattering from 4-aminothiophenol molecules embedded inside Ag coated gold nanorods

    NASA Astrophysics Data System (ADS)

    Khlebtsov, Boris N.

    2016-04-01

    Here we report on the preparation of uniform Au@Ag core/shell nanorods with a controllable Ag shell thickness. 4- aminothiophenol molecules, used as the Raman reporters, were placed between the Au core and the Ag shell. The dependence of Raman intensity on the inside/surface location of the reporter molecules was studied. The interior molecules showed a strong and uniform Raman intensity, at least an order of magnitude higher than that of the molecules on the nanoparticle surface. In contrast to usual surface-functionalized Raman tags, aggregation and clustering of nanoparticles with embedded molecules decreased the SERS signal. The findings from this study provide the basis for a novel technique of low analyte concentration detection based on high SERS response inside the core/shell metal nanostructures.

  20. Emission of ZnO:Ag nanorods obtained by ultrasonic spray pyrolysis

    NASA Astrophysics Data System (ADS)

    Velázquez Lozada, E.; Torchynska, T. V.; Casas Espinola, J. L.; Pérez Millan, B.

    2014-11-01

    Scanning electronic microscopy (SEM), X ray diffraction (XRD), photoluminescence (PL) and its temperature dependence have been studied in ZnO:Ag nanorods (NRs) prepared by the ultrasonic spray pyrolysis (USP) method. The time variation at the growth of ZnO:Ag films permits modifying the ZnO phase from the amorphous to crystalline, to change the size of ZnO:Ag NRs and to vary their emission spectra. PL spectra of ZnO:Ag NRs versus temperature has been investigated. This study reveals that the PL band related to the acceptor AgZn (LO phonon replicas of an acceptor bound exciton, ABE (2.877 eV)), and its second-order diffraction peak (1.44 eV) disappeared in the temperature range of 10-170 K with the formation of free exciton (FX). The PL intensity of defect related PL bands decreases monotonously in the range 10-300 K with the activation energy of 13 meV. The PL band (3.22 eV), related to the LO phonon replica of free exciton (FX-2LO) and its second-order diffraction peak (1.61 eV) increase monotonously in the range 10-300 K. FX related peak dominates in PL spectra at room temperature that testifies on the high quality of ZnO:Ag films prepared by the USP technology.

  1. Synthesis of reduced graphene oxide/ZnO nanorods composites on graphene coated PET flexible substrates

    SciTech Connect

    Huang, Lei Guo, Guilue; Liu, Yang; Chang, Quanhong; Shi, Wangzhou

    2013-10-15

    Graphical abstract: - Highlights: • ZnO nanorods synthesized on CVD-graphene and rGO surfaces, respectively. • ZnO/CVD-graphene and ZnO/rGO form a distinctive porous 3D structure. • rGO/ZnO nanostructures possibility in energy storage devices. - Abstract: In this work, reduced graphene oxide (rGO)/ZnO nanorods composites were synthesized on graphene coated PET flexible substrates. Both chemical vapor deposition (CVD) graphene and reduced graphene oxide (rGO) films were prepared following by hydrothermal growth of vertical aligned ZnO nanorods. Reduced graphene sheets were then spun coated on the ZnO materials to form a three dimensional (3D) porous nanostructure. The morphologies of the ZnO/CVD graphene and ZnO/rGO were investigated by SEM, which shows that the ZnO nanorods grown on rGO are larger in diameters and have lower density compared with those grown on CVD graphene substrate. As a result of fact, the rough surface of nano-scale ZnO on rGO film allows rGO droplets to seep into the large voids of ZnO nanorods, then to form the rGO/ZnO hierarchical structure. By comparison of the different results, we conclude that rGO/ZnO 3D nanostructure is more desirable for the application of energy storage devices.

  2. Synthesis and Characterization of Supported CuInSe2 Nanorod Arrays on Rigid Substrates

    NASA Astrophysics Data System (ADS)

    Zhang, Zhong-wei; Li, Ji; Liu, Ji-lei; Zhu, Chang-fei

    2011-02-01

    Copper indium diselenide nanorod arrays were electrodeposited on tungsten/silicon rigid substrates using porous anodic alumina as growth template. The porous anodic alumina templates were prepared by anodizing aluminum films which were sputtered onto the tungsten/silicon substrates. A selective chemical etching was used to penetrate the barrier layer at the bottom of the alumina channels before electrodeposition, which enables direct electrical and chemical contact with the underside substrate electrode. The as-deposited samples were annealed at 450 °C in vacuum. Scanning electron microscopy revealed that the nanorods were dense and compact with diameter of about 100 nm, length of approximate 1 μm, and the aspect ratio of 10. X-ray diffraction, micro-Raman spectroscopy, and high resolution transmission electron microscopy showed that chalcopyrite polycrystalline structure and high purity CuInSe2 nanorods were obtained. The grain size was large in the rod axial direction. Energy-dispersive X-ray spectroscopy showed the composition was nearly stoichiometric. The energy band gap of this nanorod arrays was analyzed by fundamental absorption spectrum and was evaluated to be 0.96 eV.

  3. 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.

  4. Synthesis, microstructure, and cathodoluminescence of [0001]-oriented GaN nanorods grown on conductive graphite substrate.

    PubMed

    Yuan, Fang; Liu, Baodan; Wang, Zaien; Yang, Bing; Yin, Yao; Dierre, Benjamin; Sekiguchi, Takashi; Zhang, Guifeng; Jiang, Xin

    2013-11-27

    One-dimensional GaN nanorods with corrugated morphology have been synthesized on graphite substrate without the assistance of any metal catalyst through a feasible thermal evaporation process. The morphologies and microstructures of GaN nanorods were characterized by X-ray powder diffraction (XRD), scanning electron microscopy (SEM) and high-resolution transmission electron microscopy (HRTEM). The results from HRTEM analysis indicate that the GaN nanorods are well-crystallized and exhibit a preferential orientation along the [0001] direction with Ga(3+)-terminated (101̅1) and N(3-)-terminated (101̅1̅) as side facets, finally leading to the corrugated morphology surface. The stabilization of the electrostatic surface energy of {101̅1} polar surface in a wurtzite-type hexagonal structure plays a key role in the formation of GaN nanorods with corrugated morphology. Room-temperature cathodoluminescence (CL) measurements show a near-band-edge emission (NBE) in the ultraviolet range and a broad deep level emission (DLE) in the visible range. The crystallography and the optical emissions of GaN nanorods are discussed. PMID:24164686

  5. Direct growth of cerium oxide nanorods on diverse substrates for superhydrophobicity and corrosion resistance

    NASA Astrophysics Data System (ADS)

    Cho, Young Jun; Jang, Hanmin; Lee, Kwan-Soo; Kim, Dong Rip

    2015-06-01

    Superhydrophobic surfaces with anti-corrosion properties have attracted great interest in many industrial fields, particularly to enhance the thermal performance of offshore applications such as heat exchangers, pipelines, power plants, and platform structures. Nanostructures with hydrophobic materials have been widely utilized to realize superhydrophobicity of surfaces, and cerium oxide has been highlighted due to its good corrosion resistive and intrinsically hydrophobic properties. However, few studies of direct growth of cerium oxide nanostructures on diverse substrates have been reported. Herein we report a facile hydrothermal method to directly grow cerium oxide nanorods on diverse substrates, such as aluminum alloy, stainless steel, titanium, and silicon. Diverse substrates with cerium oxide nanorods exhibited superhydrophobicity with no hydrophobic modifiers on their surfaces, and showed good corrosion resistive properties in corrosive medium. We believe our method could pave the way for realization of scalable and sustainable corrosion resistive superhydrophobic surfaces in many industrial fields.

  6. Green Synthesis of Ag and Pd Nanospheres, Nanowires, and Nanorods Using Vitamin B2: Catalytic Polymerisation of Aniline and Pyrrole

    EPA Science Inventory

    For the first time, we report green chemistry approach using vitamin B2 in the synthesis of silver (Ag) and palladium (Pd), nanospheres, nanowires and nanorods at room temperature without using any harmful reducing agents, such as sodium borohydride (NaBH4) or hydroxylamine hydro...

  7. Selective photochemical synthesis of Ag nanoparticles on position-controlled ZnO nanorods for the enhancement of yellow-green light emission

    NASA Astrophysics Data System (ADS)

    Park, Hyeong-Ho; Zhang, Xin; Lee, Keun Woo; Sohn, Ahrum; Kim, Dong-Wook; Kim, Joondong; Song, Jin-Won; Choi, Young Su; Lee, Hee Kwan; Jung, Sang Hyun; Lee, In-Geun; Cho, Young-Dae; Shin, Hyun-Beom; Sung, Ho Kun; Park, Kyung Ho; Kang, Ho Kwan; Park, Won-Kyu; Park, Hyung-Ho

    2015-12-01

    A novel technique for the selective photochemical synthesis of silver (Ag) nanoparticles (NPs) on ZnO nanorod arrays is established by combining ultraviolet-assisted nanoimprint lithography (UV-NIL) for the definition of growth sites, hydrothermal reaction for the position-controlled growth of ZnO nanorods, and photochemical reduction for the decoration of Ag NPs on the ZnO nanorods. During photochemical reduction, the size distribution and loading of Ag NPs on ZnO nanorods can be tuned by varying the UV-irradiation time. The photochemical reduction is hypothesized to facilitate the adsorbed citrate ions on the surface of ZnO, allowing Ag ions to preferentially form Ag NPs on ZnO nanorods. The ratio of visible emission to ultraviolet (UV) emission for the Ag NP-decorated ZnO nanorod arrays, synthesized for 30 min, is 20.5 times that for the ZnO nanorod arrays without Ag NPs. The enhancement of the visible emission is believed to associate with the surface plasmon (SP) effect of Ag NPs. The Ag NP-decorated ZnO nanorod arrays show significant SP-induced enhancement of yellow-green light emission, which could be useful in optoelectronic applications. The technique developed here requires low processing temperatures (120 °C and lower) and no high-vacuum deposition tools, suitable for applications such as flexible electronics.A novel technique for the selective photochemical synthesis of silver (Ag) nanoparticles (NPs) on ZnO nanorod arrays is established by combining ultraviolet-assisted nanoimprint lithography (UV-NIL) for the definition of growth sites, hydrothermal reaction for the position-controlled growth of ZnO nanorods, and photochemical reduction for the decoration of Ag NPs on the ZnO nanorods. During photochemical reduction, the size distribution and loading of Ag NPs on ZnO nanorods can be tuned by varying the UV-irradiation time. The photochemical reduction is hypothesized to facilitate the adsorbed citrate ions on the surface of ZnO, allowing Ag ions to

  8. Growth of TiO2 nanorods on a Ta substrate by metal-organic chemical vapor deposition.

    PubMed

    Lee, Kang Suk; Hyun, Jae-Sung; Seo, Hyun Ook; Kim, Young Dok; Boo, Jin-Hyo

    2010-05-01

    TiO2 nanorods were successfully grown on Tantalum (Ta) substrates using titanium tetra isopropoxide (TTIP) as a single precursor without any carriers or bubbling gases. For characterization of the TiO2 structures, scanning electron microscopy (SEM), X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS) were employed. For substrate temperatures below 800 degrees C, a rough film structure without nanorods could be found. However, at a sample temperature of 800 degrees C, nanorod structures with a respective diameter and length of 0.1 approximately 0.2 microm and 0.7 approximately 1.5 microm, respectively, could be synthesized. The nanorods exhibited a rutile phase with a 2:1 stoichiometry of O:Ti, identified using XRD and XPS. When the growth temperature exceeded 800 degrees C, agglomeration of the nanorods was identified. PMID:20358953

  9. Effects of surfactants on visible-light-driven photocatalytic hydrogen evolution activities of AgInZn7S9 nanorods

    NASA Astrophysics Data System (ADS)

    Peng, Yong; Shang, Lu; Cao, Yitao; Wang, Qing; Zhao, Yufei; Zhou, Chao; Bian, Tong; Wu, Li-Zhu; Tung, Chen-Ho; Zhang, Tierui

    2015-12-01

    Hydrophobic quaternary AgInZn7S9 nanorods with good visible-light response prepared via high-temperature pyrolysis method were transferred into aqueous solutions by inserting surfactants into their hydrophobic ligand layer for improved photocatalytic H2 production. Photocatalytic H2 evolution tests of AgInZn7S9 nanorods showed that the surfactants on their surfaces have a significant effect on their H2 evolution activities. Specifically, anionic surfactants can promote H2 evolution by enriching protons on the surface of AgInZn7S9 nanorods.

  10. Bending effects of ZnO nanorod metal–semiconductor–metal photodetectors on flexible polyimide substrate

    PubMed Central

    2012-01-01

    The authors report the fabrication and I-V characteristics of ZnO nanorod metal–semiconductor–metal photodetectors on flexible polyimide substrate. From field-emission scanning electron microscopy and X-ray diffraction spectrum, ZnO nanorods had a (0002) crystal orientation and a wurtzite hexagonal structure. During the I-V and response measurement, the flexible substrates were measured with (i.e., the radius of curvatures was 0.2 cm) and without bending. From I-V results, the dark current decreased, and the UV-to-visible rejection ratio increased slightly in bending situation. The decreasing tendency of the dark current under bending condition may be attributed to the increase of the Schottky barrier height. PMID:22494967

  11. Low-Cost Substrates for High-Performance Nanorod Array LEDs

    SciTech Connect

    Sands, Timothy; Stach, Eric; Garcia, Edwin

    2009-04-30

    The completed project, entitled Low-Cost Substrates for High-Performance Nanorod LEDs, targeted the goal of a phosphor-free nanorod-based white LED with IQE > 50% across the spectrum from 450 nm to 600 nm on metallized silicon substrates. The principal achievements of this project included: Demonstration of (In,Ga)N nanopyramid heterostructures by a conventional OMVPE process. Verification of complete filtering of threading dislocations to yield dislocation-free pyramidal heterostructures. Demonstration of electroluminescence with a peak wavelength of ~600 nm from an (In,Ga)N nanopyramid array LED. Development of a reflective ZrN/AlN buffer layer for epitaxial growth of GaN films and GaN nanopyramid arrays on (111)Si.

  12. Manganese phosphide thin films and nanorods grown on gallium phosphide and on glass substrates

    NASA Astrophysics Data System (ADS)

    Nateghi, N.; Lambert-Milot, S.; Ménard, D.; Masut, R. A.

    2016-05-01

    We report a simple and fast route to grow ferromagnetic manganese phosphide polycrystalline films and nanorods on GaP and on glass substrates using metalorganic vapor phase deposition. Increasing the growth temperature (≥600 °C) and growth time (≥30 min) results in nucleation of secondary MnP crystals on the primary grains. The secondary crystals grow faster along a specific direction of orthorhombic MnP (c-axis) and form long rods (up to ~10 μm) whose diameters are in the nanoscale (20-100 nm). The nanorods can be easily detached from the glass substrate. The films exhibit ferromagnetic behavior with a range of transition temperatures, depending on the growth conditions.

  13. High-density, uniform gallium nitride nanorods grown on Au-coated silicon substrate

    NASA Astrophysics Data System (ADS)

    Cao, Chuanbao; Xiang, Xu; Zhu, Hesun

    2005-01-01

    High-density GaN nanorods with uniform diameters and lengths were successfully grown on Au-coated silicon substrate. The diameters were in the range of 50-80 nm, and the lengths ranged from 1 to 2 μm. A significant feature is that each nanorod was attached with nanoparticle at its very end, which is consistent with the vapor-liquid-solid (VLS) growth mechanism. It was also found that the as-grown final product is strongly dependent on the thickness of the Au thin film coated on the silicon substrate. According to the experimental results, we proposed that the catalytic activity of gold is determined by the size of Au particles, and just very small Au clusters exhibit effective reactivity in the growth of GaN one-dimensional nanostructures.

  14. Au@Ag nanorods based electrochemical immunoassay for immunoglobulin G with signal enhancement using carbon nanofibers-polyamidoamine dendrimer nanocomposite.

    PubMed

    Ma, Lina; Ning, Danlei; Zhang, Hongfang; Zheng, Jianbin

    2015-06-15

    Au@Ag nanorods (Au@AgNRs) was utilized to construct a novel sandwich-type electrochemical immunosensor for the detection of immunoglobulin G (IgG). The sensor was prepared by immoblizing capture antibodies on the amine-terminated nanocomposite of carbon nanofibers-polyamidoamine dendrimer (CNFs-PAMAM), whilst the trace tag was prepared by loading anti-human IgG on Au@AgNRs. The "built-in" Ag layer on Au nanorods was characterized by UV-vis extinction spectra, transmission electron microscopy and energy dispersive spectroscopy. The results of cyclic voltammetry indicated that modifying CNFs-PAMAM nanocomposite on glassy carbon electrode enabled 177 times of peak current increase of Ag in the bimetallic nanorods. The peak current was quantitatively related with the concentration of the target protein IgG via the formation of immunocomplex. After the parameter optimization, the oxidative peak current of silver was proportional to the concentration of IgG in a wide linear range of six orders of magnitude with a low detection limit of 0.5 fg mL(-1). Besides, this sensor showed acceptable reproducibility and stability, and thus the strategy reported here has great promise for extension to the other disease biomarkers. PMID:25569874

  15. DNA biosensor-based on fluorescence detection of E. coli O157:H7 by Au@Ag nanorods.

    PubMed

    Sun, Jiadi; Ji, Jian; Sun, Yanqing; Abdalhai, Mandour H; Zhang, Yinzhi; Sun, Xiulan

    2015-08-15

    A novel DNA sensor for the detection of the Escherichia coli O157:H7 (E. coli O157:H7) eaeA gene was constructed using surface enhanced fluorescence (SEF). The spacing distance dependence nature of Au@Ag nanorods surface enhanced fluorescence was investigated when the cy3-labled single strand DNA(ssDNA) and the stem-loop DNA probe modified on the nanorods was co-hybridized. The result revealed that the fluorescence intensity reached the maximum value with the spacing distance of about 10nm between cy3 and the Au@Ag nanorods surface. Based on this result, a fluorescence "ON/OFF" switch for detecting the eaeA gene of E. coli O157:H7 was constructed. Under optimal conditions, the DNA sensor produced a linear range from 10(-17) to 10(-11) M with a correlation coefficient of 0.9947 and a detection limit of 3.33×10(-18) M, and was also found to be specific in targeting eaeA. The DNA sensor demonstrated a new strategy of combining eaeA recognition and Au@Ag nanorods for fluorescence signal enhancement, and increased sensitivity in the detection of bacterial specific genes. PMID:25829221

  16. A new class of PANI-Ag core-shell nanorods with sensing dimensions.

    PubMed

    Shukla, Vineet K; Yadav, Poonam; Yadav, Raghvendra S; Mishra, Priya; Pandey, Avinash C

    2012-07-01

    A single-step, cost-effective and eco-safe synthesis of a new class of homogeneous silver-polyaniline (PANI-Ag) core-shell nanorods is carried out via mild photolysis by ultraviolet radiation from sunlight (SUN UV-radiation). X-ray diffraction (XRD) of these core-shell nanorods gives two additional peaks from PANI centered at 2θ = 20.5° and 24. 9°. A validation of the core-shell structural information is given by transmission electron spectroscopy (TEM) whereas the tubular shape morphology is determined by scanning electron microscopy (SEM). UV-Vis. absorption shows a strong blue-shift along with photoluminescence emission. Fourier transform-infrared spectroscopy (FT-IR) and energy dispersive X-ray spectroscopy (EDX) also support the core-shell formation. Thermogravimetric analysis (TGA) shows good thermal stability and allows excellent detection of hydrogen peroxide and hydrazine. The cyclic voltammetry (CV) results show excellent electro-activation, indicating its promising potential in sensing of clinical and environmental analytes. PMID:22669315

  17. Tunable Ultra-high Aspect Ratio Nanorod Architectures grown on Porous Substrate via Electromigration

    PubMed Central

    Mansourian, Ali; Paknejad, Seyed Amir; Wen, Qiannan; Vizcay-Barrena, Gema; Fleck, Roland A.; Zayats, Anatoly V.; Mannan, Samjid H.

    2016-01-01

    The interplay between porosity and electromigration can be used to manipulate atoms resulting in mass fabrication of nanoscale structures. Electromigration usually results in the accumulation of atoms accompanied by protrusions at the anode and atomic depletion causing voids at the cathode. Here we show that in porous media the pattern of atomic deposition and depletion is altered such that atomic accumulation occurs over the whole surface and not just at the anode. The effect is explained by the interaction between atomic drift due to electric current and local temperature gradients resulting from intense Joule heating at constrictions between grains. Utilizing this effect, a porous silver substrate is used to mass produce free-standing silver nanorods with very high aspect ratios of more than 200 using current densities of the order of 108 A/m2. This simple method results in reproducible formation of shaped nanorods, with independent control over their density and length. Consequently, complex patterns of high quality single crystal nanorods can be formed in-situ with significant advantages over competing methods of nanorod formation for plasmonics, energy storage and sensing applications. PMID:26923553

  18. Tunable Ultra-high Aspect Ratio Nanorod Architectures grown on Porous Substrate via Electromigration

    NASA Astrophysics Data System (ADS)

    Mansourian, Ali; Paknejad, Seyed Amir; Wen, Qiannan; Vizcay-Barrena, Gema; Fleck, Roland A.; Zayats, Anatoly V.; Mannan, Samjid H.

    2016-02-01

    The interplay between porosity and electromigration can be used to manipulate atoms resulting in mass fabrication of nanoscale structures. Electromigration usually results in the accumulation of atoms accompanied by protrusions at the anode and atomic depletion causing voids at the cathode. Here we show that in porous media the pattern of atomic deposition and depletion is altered such that atomic accumulation occurs over the whole surface and not just at the anode. The effect is explained by the interaction between atomic drift due to electric current and local temperature gradients resulting from intense Joule heating at constrictions between grains. Utilizing this effect, a porous silver substrate is used to mass produce free-standing silver nanorods with very high aspect ratios of more than 200 using current densities of the order of 108 A/m2. This simple method results in reproducible formation of shaped nanorods, with independent control over their density and length. Consequently, complex patterns of high quality single crystal nanorods can be formed in-situ with significant advantages over competing methods of nanorod formation for plasmonics, energy storage and sensing applications.

  19. Facile Synthesis of Ag Nanorods with No Plasmon Resonance Peak in the Visible Region by Using Pd Decahedra of 16 nm in Size as Seeds.

    PubMed

    Luo, Ming; Huang, Hongwen; Choi, Sang-Il; Zhang, Chao; da Silva, Robson Rosa; Peng, Hsin-Chieh; Li, Zhi-Yuan; Liu, Jingyue; He, Zhike; Xia, Younan

    2015-10-27

    This article describes a seed-mediated approach to the synthesis of Ag nanorods with thin diameters and tunable aspect ratios. The success of this method is built upon our recent progress in the synthesis of Pd decahedra as uniform samples, together with controllable sizes. When used as a seed, the Pd decahedron could direct the deposition of Ag atoms along the 5-fold axis to generate a nanorod, with its diameter being determined by the lateral dimension of the seed. We were able to generate Ag nanorods with uniform diameters down to 20 nm. Under the conditions we used for growth, symmetry breaking occurred as the Ag atoms were only deposited along one side of the Pd decahedral seed to generate a Ag nanorod with the Pd seed being positioned at one of its two ends. We also systematically investigated the localized surface plasmon resonance (LSPR) properties of the Ag nanorods. With the transverse mode kept below 400 nm, the longitudinal mode could be readily tuned from the visible to the near-infrared region by varying the aspect ratio. As an important demonstration, we obtained Ag nanorods with no LSPR peak in the visible spectrum (400-800 nm), which are attractive for applications related to the fabrication of touchscreen displays, solar films, and energy-saving smart windows. PMID:26372854

  20. Morphological and structural characterization of single-crystal ZnO nanorod arrays on flexible and non-flexible substrates

    PubMed Central

    Farhat, Omar F; Halim, Mohd M; Abdullah, Mat J; Ali, Mohammed K M

    2015-01-01

    Summary We report a facile synthesis of zinc oxide (ZnO) nanorod arrays using an optimized, chemical bath deposition method on glass, PET and Si substrates. The morphological and structural properties of the ZnO nanorod arrays were investigated using various techniques such as field emission scanning electron microscopy (FESEM) and X-ray diffraction (XRD) measurements, which revealed the formation of dense ZnO nanorods with a single crystal, hexagonal wurtzite structure. The aspect ratio of the single-crystal ZnO nanorods and the growth rate along the (002) direction was found to be sensitive to the substrate type. The lattice constants and the crystallite size of the fabricated ZnO nanorods were calculated based on the XRD data. The obtained results revealed that the increase in the crystallite size is strongly associated with the growth conditions with a minor dependence on the type of substrate. The Raman spectroscopy measurements confirmed the existence of a compressive stress in the fabricated ZnO nanorods. The obtained results illustrated that the growth of high quality, single-crystal ZnO nanorods can be realized by adjusting the synthesis conditions. PMID:25821712

  1. Photodeposition of Ag2S on TiO2 nanorod arrays for quantum dot-sensitized solar cells

    PubMed Central

    2013-01-01

    Ag2S quantum dots were deposited on the surface of TiO2 nanorod arrays by a two-step photodeposition. The prepared TiO2 nanorod arrays as well as the Ag2S deposited electrodes were characterized by X-ray diffraction, scanning electron microscope, and transmission electron microscope, suggesting a large coverage of Ag2S quantum dots on the ordered TiO2 nanorod arrays. UV–vis absorption spectra of Ag2S deposited electrodes show a broad absorption range of the visible light. The quantum dot-sensitized solar cells (QDSSCs) based on these electrodes were fabricated, and the photoelectrochemical properties were examined. A high photocurrent density of 10.25 mA/cm2 with a conversion efficiency of 0.98% at AM 1.5 solar light of 100 mW/cm2 was obtained with an optimal photodeposition time. The performance of the QDSSC at different incident light intensities was also investigated. The results display a better performance at a lower incident light level with a conversion efficiency of 1.25% at 47 mW/cm2. PMID:23286551

  2. Multishell Au/Ag/SiO2 nanorods with tunable optical properties as single particle orientation and rotational tracking probes

    DOE PAGESBeta

    Chen, Kuangcai; Lin, Chia -Cheng; Vela, Javier; Fang, Ning

    2015-04-07

    In this study, three-layer core–shell plasmonic nanorods (Au/Ag/SiO2–NRs), consisting of a gold nanorod core, a thin silver shell, and a thin silica layer, were synthesized and used as optical imaging probes under a differential interference contrast microscope for single particle orientation and rotational tracking. The localized surface plasmon resonance modes were enhanced upon the addition of the silver shell, and the anisotropic optical properties of gold nanorods were maintained. The silica coating enables surface functionalization with silane coupling agents and provides enhanced stability and biocompatibility. Taking advantage of the longitudinal LSPR enhancement, the orientation and rotational information of the hybridmore » nanorods on synthetic lipid bilayers and on live cell membranes were obtained with millisecond temporal resolution using a scientific complementary metal-oxide-semiconductor camera. The results demonstrate that the as-synthesized hybrid nanorods are promising imaging probes with improved sensitivity and good biocompatibility for single plasmonic particle tracking experiments in biological systems.« less

  3. Gold nanorods 3D-supercrystals as surface enhanced Raman scattering spectroscopy substrates for the rapid detection of scrambled prions

    PubMed Central

    Alvarez-Puebla, Ramón A.; Agarwal, Ashish; Manna, Pramit; Khanal, Bishnu P.; Aldeanueva-Potel, Paula; Carbó-Argibay, Enrique; Pazos-Pérez, Nicolas; Vigderman, Leonid; Zubarev, Eugene R.; Kotov, Nicholas A.; Liz-Marzán, Luis M.

    2011-01-01

    Highly organized supercrystals of Au nanorods with plasmonic antennae enhancement of electrical field have made possible fast direct detection of prions in complex biological media such as serum and blood. The nearly perfect three-dimensional organization of nanorods render these systems excellent surface enhanced Raman scattering spectroscopy substrates with uniform electric field enhancement, leading to reproducibly high enhancement factor in the desirable spectral range. PMID:21536908

  4. Formation of core-shell Au@Ag nanorods induced by catecholamines: A comparative study and an analytical application.

    PubMed

    Gorbunova, M V; Apyari, V V; Dmitrienko, S G; Garshev, A V

    2016-09-14

    Gold nanorods (AuNRs) stabilized by cetyltrimethylammonium bromide (CTAB) were synthesized and an interaction of catecholamines (CAs) with silver ions in the presence of the obtained AuNRs was studied. The reaction results into formation of core-shell Au@Ag nanorods (Au@AgNRs) and leads to a hypsochromic shift of the long-wave surface plasmon resonance (SPR) band in the absorption spectrum of AuNRs. The influence of a CA structure, excess of CTAB, interaction time, pH, concentration of AuNRs, silver ions and CAs on this interaction was studied. Based on correlation of the NRs spectral characteristics with the concentration of CAs, a method for spectrophotometric determination of dobutamine, epinephrine, norepinephrine and dopamine with detection limits 27, 18, 16 and 13 μg L(-1), respectively, has been developed. The method can be applied to the analysis of medicines. PMID:27566354

  5. Polydopamine-Coated Porous Substrates as a Platform for Mineralized β-FeOOH Nanorods with Photocatalysis under Sunlight.

    PubMed

    Zhang, Chao; Yang, Hao-Cheng; Wan, Ling-Shu; Liang, Hong-Qing; Li, Hanying; Xu, Zhi-Kang

    2015-06-01

    Immobilization of photo-Fenton catalysts on porous materials is crucial to the efficiency and stability for water purification. Here we report polydopamine (PDA)-coated porous substrates as a platform for in situ mineralizing β-FeOOH nanorods with enhanced photocatalytic performance under sunlight. The PDA coating plays multiple roles as an adhesive interface, a medium inducing mineral generation, and an electron transfer layer. The mineralized β-FeOOH nanorods perfectly wrap various porous substrates and are stable on the substrates that have a PDA coating. The immobilized β-FeOOH nanorods have been shown to be efficient for degrading dyes in water via a photo-Fenton reaction. The degradation efficiency reaches approximately 100% in 60 min when the reaction was carried out with H2O2 under visible light, and it remains higher than 90% after five cycles. We demonstrate that the PDA coating promotes electron transfer to reduce the electron-hole recombination rate. As a result, the β-FeOOH nanorods wrapped on the PDA-coated substrates show enhanced photocatalytic performance under direct sunlight in the presence of H2O2. Moreover, this versatile platform using porous materials as the substrate is useful in fabricating β-FeOOH nanorods-based membrane reactor for wastewater treatment. PMID:25969860

  6. Highly Sensitive and Selective Surface-Enhanced Raman Spectroscopy Label-free Detection of 3,3',4,4'-Tetrachlorobiphenyl Using DNA Aptamer-Modified Ag-Nanorod Arrays.

    PubMed

    Sun, Kexi; Huang, Qing; Meng, Guowen; Lu, Yilin

    2016-03-01

    An improved label-free approach for highly sensitive and selective detection of 3,3',4,4'-tetrachlorobiphenyl (PCB-77), a type of polychlorinated biphenyl, via surface-enhanced Raman spectroscopy (SERS) using DNA aptamer-modified Ag-nanorod arrays as the effective substrate is reported. The devised system consists of Ag-nanorod (Ag-NR) arrays with the PCB-77 binding aptamers anchored covalently to the Ag surfaces through a thiol linker. The aptamers are made of single-stranded DNA (ssDNA) oligomers, with one end standing on the Ag surface, and upon conjugation with PCB-77, the ssDNA molecules can change their conformation to hairpin loops, so that the Raman intensity of guanines at the other end of the DNA strand increases accordingly. As such, the intensity ratio I(656 cm(-1))/I(733 cm(-1)) increases concomitantly with the increase of the concentration of PCB-77, making the quantitative evaluation of trace amounts of PCB-77 attainable. Moreover, it is found that the DNA aptamer-based Ag-NR arrays can be more responsive with a lower and optimal density of the DNA molecules modified on the substrate surface, and the best sensitivity for detection of PCB-77 can be achieved with the lower detection limit approaching 3.3 × 10(-8) M. This work therefore demonstrates that the design of aptamer-modified Ag-NRs can be used as a practically promising SERS substrate for label-free trace detection of persistent organic pollutants (POPs) in the environment. PMID:26849392

  7. SERS substrates formed by gold nanorods deposited on colloidal silica films

    PubMed Central

    2013-01-01

    We describe a new approach to the fabrication of surface-enhanced Raman scattering (SERS) substrates using gold nanorod (GNR) nanopowders to prepare concentrated GNR sols, followed by their deposition on an opal-like photonic crystal (OPC) film formed on a silicon wafer. For comparative experiments, we also prepared GNR assemblies on plain silicon wafers. GNR-OPC substrates combine the increased specific surface, owing to the multilayer silicon nanosphere structure, and various spatial GNR configurations, including those with possible plasmonic hot spots. We demonstrate here the existence of the optimal OPC thickness and GNR deposition density for the maximal SERS effect. All other things being equal, the analytical integral SERS enhancement of the GNR-OPC substrates is higher than that of the thick, randomly oriented GNR assemblies on plain silicon wafers. Several ways to further optimize the strategy suggested are discussed. PMID:23697339

  8. Low-temperature growth of well-aligned zinc oxide nanorod arrays on silicon substrate and their photocatalytic application

    PubMed Central

    Azam, Ameer; Babkair, Saeed Salem

    2014-01-01

    Well-aligned and single-crystalline zinc oxide (ZnO) nanorod arrays were grown on silicon (Si) substrate using a wet chemical route for the photodegradation of organic dyes. Structural analysis using X-ray diffraction, high-resolution transmission electron microscopy, and selected area electron diffraction confirmed the formation of ZnO nanorods grown preferentially oriented in the (001) direction and with a single phase nature with a wurtzite structure. Field emission scanning electron microscopy and transmission electron microscopy micrographs showed that the length and diameter of the well-aligned rods were about ~350–400 nm and ~80–90 nm, respectively. Raman scattering spectra of ZnO nanorod arrays revealed the characteristic E2 (high) mode that is related to the vibration of oxygen atoms in the wurtzite ZnO. The photodegradation of methylene blue (MB) using ZnO nanorod arrays was performed under ultraviolet light irradiation. The results of photodegradation showed that ZnO nanorod arrays were capable of degrading ~80% of MB within 60 minutes of irradiation, whereas ~92% of degradation was achieved in 120 minutes. Complete degradation of MB was observed after 270 minutes of irradiation time. Owing to enhanced photocatalytic degradation efficiency and low-temperature growth method, prepared ZnO nanorod arrays may open up the possibility for the successful utilization of ZnO nanorod arrays as a future photocatalyst for environmental remediation. PMID:24812511

  9. Seedless Pattern Growth of Quasi-Aligned ZnO Nanorod Arrays on Cover Glass Substrates in Solution

    NASA Astrophysics Data System (ADS)

    Ahsanulhaq, Q.; Kim, Jin Hwan; Kim, Jeong Hyun; Hahn, Y. B.

    2010-03-01

    A hybrid technique for the selective growth of ZnO nanorod arrays on wanted areas of thin cover glass substrates was developed without the use of seed layer of ZnO. This method utilizes electron-beam lithography for pattern transfer on seedless substrate, followed by solution method for the bottom-up growth of ZnO nanorod arrays on the patterned substrates. The arrays of highly crystalline ZnO nanorods having diameter of 60 ± 10 nm and length of 750 ± 50 nm were selectively grown on different shape patterns and exhibited a remarkable uniformity in terms of diameter, length, and density. The room temperature cathodluminescence measurements showed a strong ultraviolet emission at 381 nm and broad visible emission at 585-610 nm were observed in the spectrum.

  10. Structure, morphologies and dye removal efficiency of ZnO nanorods grown on polycrystalline Zn substrate

    NASA Astrophysics Data System (ADS)

    Yin, Tiantian; Chen, Nan; Zhang, Yingying; Cai, Xiaoyan; Wang, Yude

    2014-10-01

    Rod-like ZnO with the different morphologies were grown on polycrystalline Zn substrate by a simple hydrothermal process in a NaOH or NH4OH solution at the hydrothermal temperature range from 80 to 150 °C for different reaction time. Variations preparation in the different alkali solution concentration, hydrothermal temperature, and reaction times were explored to shed light on the morphology of the rod-like nanostructures. The thorough structural characterization including X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), electron diffraction, and X-ray photoelectron spectrum (XPS) were employed to examine the morphology and the microstructure of the final products. It was found that alkali solution concentration, hydrothermal temperature and time have important influence on the morphology of the rod-like nanostructures. The dye removal efficiency of ZnO nanorods was explored by the decoloration of azo dye Congo red (CR). In order to obtain the optimum removal conditions of Congo red, the performance of removing CR with various initial concentrations by ZnO nanorods on Zn substrates with different morphologies was tested under various ambient conditions (visible light illumination and darkness). All prepared samples showed an excellent dye removal efficiency for organic pollutants CR from wastewater, making them promising candidates for the wastewater treatment.

  11. Modeling wrinkled-assisted assembly of ordered nanoparticles and nanorods on a wavy substrate

    NASA Astrophysics Data System (ADS)

    Luppi Sato, Camila; Yeh, Peter; Alexeev, Alexander; Mayer, Martin; Probst, Patrick; Fery, Andreas

    2015-11-01

    Wrinkle-assisted assembly is a technique that allows for fabrication of ordered structures of nanoparticles and nanorods on hydrophilic substrates. As an intermediate step in this process, nanoparticles are deposited within microscopically wrinkled surfaces, where they organize into patterned structures upon solvent evaporation. However, the dependence of the resulting pattern on nanoparticle concentration, particle size and shape, and substrate geometry is not well understood. We develop a model of the ordering process using dissipative particle dynamics (DPD) to predict the resulting nanostructures. We approximate the wavy sheet as a sinusoidal surface. One layer of DPD liquid containing nanoparticles fills the surface, while another layer of DPD fluid acts as the gaseous phase. We model the evaporative process by gradually replacing DPD liquid particles with DPD gaseous particles. The results of our work are useful in designing surface patterns that exhibit strong plasmonic coupling. Financial support from NSF CAREER Award DMR-1255288 is gratefully acknowledged.

  12. SERS active Ag encapsulated Fe@SiO2 nanorods in electromagnetic wave absorption and crystal violet detection.

    PubMed

    Senapati, Samarpita; Srivastava, Suneel Kumar; Singh, Shiv Brat; Kulkarni, Ajit R

    2014-11-01

    The present work is focused on the preparation of Fe nanorods by the chemical reduction of FeCl3 (aq) using NaBH4 in the presence of glycerol as template followed by annealing of the product at 500°C in the presence of H2 gas flow. Subsequently, its surface has been modified by silica followed by silver nanoparticles to form silica coated Fe (Fe@SiO2) and Ag encapsulated Fe@SiO2 nanostructure employing the Stöber method and silver mirror reaction respectively. XRD pattern of the products confirmed the formation of bcc phase of iron and fcc phase of silver, though silica remained amorphous. FESEM images established the growth of iron nanorods from the annealed product and also formation of silica and silver coating on its surface. The appearance of the characteristics bands in FTIR confirmed the presence of SiO2 on the Fe surface. Magnetic measurements at room temperature indicated the ferromagnetic behavior of as prepared iron nanorods, Fe@SiO2 and silver encapsulated Fe@SiO2 nanostructures. All the samples exhibited strong microwave absorption property in the high frequency range (10GHz), though it is superior for Ag encapsulated Fe@SiO2 (-14.7dB) compared with Fe@SiO2 (-9.7dB) nanostructures of the same thickness. The synthesized Ag encapsulated Fe@SiO2 nanostructure also exhibited the SERS phenomena, which is useful in the detection of the carcinogenic dye crystal violet (CV) upto the concentration of 10(-10)M. All these findings clearly demonstrate that the Ag encapsulated Fe@SiO2 nanostructure could efficiently be used in the environmental remediation. PMID:25262081

  13. Confined migration of induced hot electrons in Ag/graphene/TiO2 composite nanorods for plasmonic photocatalytic reaction.

    PubMed

    Huang, Hung Ji; Zhen, Shi-Yuan; Li, Ping-Yu; Tzeng, Shien-Der; Chiang, Hai-Pang

    2016-07-11

    Confined migration of hot electrons is presented in nanorods of layered Ag/graphene/TiO2 structure for highly efficient plasmonic photocatalytic water treatment. The light-illuminating titanium dioxide (TiO2) nanorods provide a large amount of high-energy hot electrons for the generation of highly-active superoxide radical (*O2 -) that leads to the degradation of organics in water. Comparison between photocatalytic processing efficiency by photocatalysts with various composite materials were presented based on the preferred propagation path of induced hot electrons that leads to generation of *O2 -. The best results done by Ag/graphene/TiO2 nanorods showed that the sandwiched layer of graphene on TiO2 nanorods collects the induced hot electrons and results in high efficiency photocatalytic reaction. PMID:27410833

  14. Hexagonal core-shell and alloy Au/Ag nanodisks on ZnO nanorods and their optical enhancement effect

    PubMed Central

    2014-01-01

    Au and Ag hybrid hexagonal nanodisks were synthesized on ZnO nanorods' (0002) surface via a new two-step deposition-annealing method. The structural, compositional, as well as optical investigations were carried out systematically to find out the nanodisks' formation mechanism and optical enhancement effect. It was shown that the core-shell Au/Ag nanodisk can be formed under rapid annealing temperature of 500°C, while Au/Ag alloy nanodisks are formed if higher temperatures (>550°C) are applied. The optical effect from these nanodisks was studied through photoluminescence and absorption spectroscopy. It was found that the carrier-plasmon coupling together and carrier transfer between metal and ZnO contribute to the emission enhancement. Furthermore, the results suggest that the composition of nanodisk on the vicinity of metal/ZnO interface plays an important role in terms of the enhancement factors. PMID:24936157

  15. Facile synthesis of hybrid nanorods with the Sb2Se3/AgSbSe2 heterojunction structure for high performance photodetectors.

    PubMed

    Chen, Shuo; Qiao, Xvsheng; Wang, Fengxia; Luo, Qun; Zhang, Xianghua; Wan, Xia; Xu, Yang; Fan, Xianping

    2016-01-28

    An effective colloidal process involving the hot-injection method is developed to synthesize uniform single-crystalline Sb2Se3 nanorods in high yields. The photoconductive characteristics of the as-synthesized Sb2Se3 nanorods are investigated by developing a film-based photodetector and this device displays a remarkable response to visible light with an "ON/OFF" ratio as high as 50 (with an incident light density of 12.05 mW cm(-2)), short response/recovery times and long-term durability. To overcome the challenge of the intrinsic low electrical conductivity of Sb2Se3, hybrid nanorods with the Sb2Se3/AgSbSe2 heterojunction structure having a type-II band alignment are firstly prepared. The electric current of the photodetector based on the Sb2Se3/AgSbSe2 hybrid nanorod film has been significantly increased both in the dark and under light illumination. The responsivity of the photodetector based on the Sb2Se3/AgSbSe2 hybrid nanorod film is about 4.2 times as much as that of the photodetector based on the Sb2Se3 nanorod film. This improvement can be considered as an important step to promote Sb2Se3 based semiconductors for applications in high performance photodetectors. PMID:26743461

  16. General Route to ZnO Nanorod Arrays on Conducting Substrates via Galvanic-cell-based approach

    NASA Astrophysics Data System (ADS)

    Zheng, Zhaoke; Lim, Zhi Shiuh; Peng, Yuan; You, Lu; Chen, Lang; Wang, Junling

    2013-08-01

    Wurtzite ZnO nanorod exhibits many unique properties, which make it promising for various optoelectronic applications. To grow well-aligned ZnO nanorod arrays on various substrates, a seed layer is usually required to improve the density and vertical alignment. The reported works about seedless hydrothermal synthesis either require special substrates, or require external electrical field to enhance the ZnO nucleation. Here, we report a general method for the one-pot synthesis of homogenous and well-aligned ZnO nanorods on common conducting substrates without a seed layer. This method, based on the galvanic-cell structure, makes use of the contact potential between different materials as the driving force for ZnO growth. It is applicable to different conducting substrates at low temperature. More importantly, the as-grown ZnO nanorods show enhanced photoelectric response. This unique large scale low-temperature processing method could be of great importance for the application of ZnO nanostructures.

  17. Synthesis of Ag or Pt nanoparticle-deposited TiO2 nanorods for the highly efficient photoreduction of CO2 to CH4

    NASA Astrophysics Data System (ADS)

    Wang, Qingli; Dong, Peimei; Huang, Zhengfeng; Zhang, Xiwen

    2015-10-01

    Ag or Pt-deposited TiO2 nanocomposites were prepared by a simple method, in which oriented TiO2 nanorods were synthesized by a hydrothermal method and a noble metal (Ag or Pt) was deposited on TiO2 by photocatalytic reduction under UV irradiation. The oriented TiO2 nanorods with Ag or Pt nanoparticles (<20 nm) exhibited high CO2 photoreduction efficiency, with CH4 yield rates up to 16.0 ppm/g h and 10.8 ppm/g h, respectively, considerably higher than that of the pure TiO2 nanorods (4.2 ppm/g h). The improvement in the CH4 yield was attributed to the formation of a Schottky barrier and surface plasmon resonance.

  18. Optically anisotropic substrates via wrinkle-assisted convective assembly of gold nanorods on macroscopic areas

    PubMed Central

    Tebbe, Moritz; Mayer, Martin; Glatz, Bernhard A.; Hanske, Christoph; Probst, Patrick T.; Müller, Mareen B.; Karg, Matthias; Chanana, Munish; König, Tobias A. F.; Kuttner, Christian

    2015-01-01

    We demonstrate the large-scale organisation of anisotropic nanoparticles into linear assemblies displaying optical anisotropy on macroscopic areas. Monodisperse gold nanorods with a hydrophilic protein shell are arranged by dip-coating on wrinkled surfaces and subsequently transferred to indium tin oxide (ITO) substrates by capillary transfer printing. We elucidate how tuning the wrinkle amplitude enables us to precisely adjust the assembly morphology and fabricate single, double and triple nanorod lines. For the single lines, we quantify the order parameter of the assemblies as well as interparticle distances from scanning electron microscopy (SEM) images. We find an order parameter of 0.97 and a mean interparticle gap size of 7 nm. This combination of close to perfect uni-axial alignment and close-packing gives rise to pronounced macroscopic anisotropic optical properties due to strong plasmonic coupling. We characterise the optical response of the assemblies on ITO-coated glass via UV/vis/NIR spectroscopy and determine an optical order parameter of 0.91. The assemblies are thus plasmonic metamaterials, as their periodicity and building block sizes are well below the optical wavelength. The presented approach does not rely on lithographic patterning and provides access to functional materials, which could have applications in subwavelength waveguiding, photovoltaics, and for large-area metamaterial fabrication. PMID:25951174

  19. High-Quality AgGaTe2 Layers on Si Substrates with Ag2Te Buffer Layers

    NASA Astrophysics Data System (ADS)

    Uruno, Aya; Kobayashi, Masakazu

    2016-05-01

    AgGaTe2 layers were successfully grown on Si substrates by the close-spaced sublimation method. The Si substrates were confirmed to be etched during AgGaTe2 layer growth when the layer was grown directly on the substrate. To eliminate melt-back etching, a buffer layer of Ag2Te was introduced. It was found that the Ag2Te buffer layer changed into the AgGaTe2 layer during the growth process, and a uniform AgGaTe2 layer with an abrupt interface was formed. Both the diffusion of Ga into Ag2Te and the growth of AgGaTe2 occurred simultaneously. It was confirmed that uniform AgGaTe2 layers could be formed without any traces of the Ag2Te layer or melt-back etching by tuning the growth parameters. A solar cell was also fabricated using the p-AgGaTe2/n-Si heterojunction. This solar cell showed conversion efficiency of approximately 3%.

  20. High-Quality AgGaTe2 Layers on Si Substrates with Ag2Te Buffer Layers

    NASA Astrophysics Data System (ADS)

    Uruno, Aya; Kobayashi, Masakazu

    2016-09-01

    AgGaTe2 layers were successfully grown on Si substrates by the close-spaced sublimation method. The Si substrates were confirmed to be etched during AgGaTe2 layer growth when the layer was grown directly on the substrate. To eliminate melt-back etching, a buffer layer of Ag2Te was introduced. It was found that the Ag2Te buffer layer changed into the AgGaTe2 layer during the growth process, and a uniform AgGaTe2 layer with an abrupt interface was formed. Both the diffusion of Ga into Ag2Te and the growth of AgGaTe2 occurred simultaneously. It was confirmed that uniform AgGaTe2 layers could be formed without any traces of the Ag2Te layer or melt-back etching by tuning the growth parameters. A solar cell was also fabricated using the p-AgGaTe2/n-Si heterojunction. This solar cell showed conversion efficiency of approximately 3%.

  1. Synthesis and properties of boron doped ZnO nanorods on silicon substrate by low-temperature hydrothermal reaction

    NASA Astrophysics Data System (ADS)

    Yu, Qi; Li, Liuan; Li, Hongdong; Gao, Shiyong; Sang, Dandan; Yuan, Jujun; Zhu, Pinwen

    2011-05-01

    Boron doped ZnO nanorods were fabricated by hydrothermal technique on silicon substrate covered with a ZnO seed layer. It is found that the concentration of boric acid in the reaction solution plays a key role in varying the morphology and properties of the products. The growth rate along the [0 0 0 1] orientation (average size in diameter) of the doped ZnO nanorods decreased (increased) with the increase of boric acid concentration. Based on the results of XRD, EDX and XPS, it is demonstrated that the boron dopants tend to occupy the octahedral interstice sites. The photoluminescence of the ZnO nanorods related to boron doping are investigated.

  2. Hydrogen treatment-improved uniform deposition of Ag nanoparticles on ZnO nanorod arrays and their visible-light photocatalytic and surface-enhanced Raman scattering properties

    PubMed Central

    2013-01-01

    ZnO nanorod arrays were synthesized by chemical bath deposition. After heat treatment in hydrogen or air, Ag nanoparticles were deposited on ZnO nanorod arrays by photo-reduction method. The size of Ag nanoparticles as well as the surface morphology, structure, composition, and optical property of ZnO nanorod arrays before and after the deposition of Ag nanoparticles were characterized by SEM, XRD, EDS, and UV/VIS/NIR spectrophotometer. As compared to the samples with heat treatment in air or without heat treatment, the ZnO nanorod arrays after heat treatment in hydrogen allowed Ag nanoparticles to be deposited more uniformly, densely, and numerously. Also, they exhibited higher efficiency for the visible light-driven photocatalytic degradation of Rhodamine 6G (R6G) dye. The effects of the amount of Ag nanoparticles, initial dye concentration, and temperature on the photocatalytic degradation efficiency were investigated. Furthermore, they also exhibited better surface-enhanced Raman scattering property for the detection of R6G dyes. PMID:23866904

  3. Study on the photogenerated charge transfer and photoelectrocatalytic performance of Ag/ZnO nanorod arrays under the irradiation of simulated sun light

    NASA Astrophysics Data System (ADS)

    Mu, Zhao; Yan, Weiping; Zhao, Rusong; Lin, Yanhong

    2015-06-01

    Ag/ZnO nanorod arrays with enhanced photoelectric response properties under simulated sun light were synthesized by a facile two-step process and characterized by x-ray powder diffraction (XRD), UV-vis diffuse reflectance spectra (UV-vis DRS) and the field emission scanning electron microscopy (FESEM). The photoelectrocatalytic (PEC) activities of the catalysts were evaluated by degrading efficiency of methylene blue (MB) dye under simulated sun light. The MB removal rate can reach 85% after the irradiation of simulated sunlight for 30 min. Surface photovoltage (SPV) measurements and transient photovoltage (TPV) spectra demonstrated that Ag loading improved the utilization of the visible spectral absorption of ZnO nanorod arrays, as well as their separation efficiency of photogenerated electron-hole pairs, which may be due to the capture effect of Ag nanoparticles for free electrons under the irradiation of simulated sunlight. The photoelectrochemical investigations indicated that the Ag/ZnO nanorod arrays showed enhanced photocurrent generation efficiency, and had a more effective interface charge transfer path. The fast PEC degradation of MB is ascribed to the highly ordered nanorod architecture, the large effective mass of the photogenerated holes on the surface of ZnO induced by Ag nanoparticles loading, as well as the effective transport of photogenerated charge carriers under the effect of external electric field.

  4. W{sub 18}O{sub 49} nanorods decorated with Ag/AgCl nanoparticles as highly-sensitive gas-sensing material and visible-light-driven photocatalyst

    SciTech Connect

    Sun Shibin; Chang Xueting; Dong Lihua; Zhang Yidong; Li Zhenjiang; Qiu Yanyan

    2011-08-15

    A novel gas-sensing material and photocatalyst was successfully obtained by decorating Ag/AgCl nanoparticles on the W{sub 18}O{sub 49} nanorods through a clean photochemical route. The as-prepared samples were characterized using combined techniques of X-ray diffractometry, electron microscopy, energy dispersive X-ray spectrometry, and X-ray photoelectron spectroscopy. Gas-sensing measurements indicate that the Ag/AgCl/W{sub 18}O{sub 49} NRs sensors exhibit superior reducing gas-sensing properties to those of bare W{sub 18}O{sub 49} NRs, and they are highly selective and sensitive to NH{sub 3}, acetone, and H{sub 2}S with short response and recovery times. The Ag/AgCl/W{sub 18}O{sub 49} NRs photocatlysts also possess higher photocatalytic performance than bare W{sub 18}O{sub 49} NRs for degradation of methyl orange under simulated sunlight irradiation. Possible mechanisms concerning the enhancement of gas-sensing and photocatalytic activities of the Ag/AgCl/W{sub 18}O{sub 49} NRs composite were proposed. - Graphical Abstract: The Ag/AgCl nanoparticles adhered well to the W{sub 18}O{sub 49} nanorod. The Ag could act as transfer center of the photoexcited carriers, prohibiting their recombinations in both W{sub 18}O{sub 49} and AgCl. Highlights: > Ag/AgCl/W{sub 18}O{sub 49} NRs were successfully obtained via a clean photochemical route. > The Ag/AgCl nanoparticles decorated on the W{sub 18}O{sub 49} NRs possessed cladding structure. > The Ag/AgCl/W{sub 18}O{sub 49} NRs exhibited excellent gas-sensing and photocatalytic properties.

  5. Ag-doped ZnO nanorods coated metal wire meshes as hierarchical photocatalysts with high visible-light driven photoactivity and photostability.

    PubMed

    Hsu, Mu-Hsiang; Chang, Chi-Jung

    2014-08-15

    Ag-doped ZnO nanorods were grown on stainless-steel wire meshes to fabricate the hierarchical photocatalysts with excellent visible light driven activity and anti-photocorrosion property. Effects of Ag doping and the surface structure on the surface chemistry, surface wetting properties, absorption band shift, photoelectrochemical response, and photocatalytic decolorization properties of the hierarchical photocatalysts, together with the stability of photocatalytic activity for recycled photocatalysts were investigated. Ag doping leads to red-shift in the absorption band and increased visible light absorption. Nanorods coated wire meshes hierarchical structure not only increases the surface area of photocatalysts but also makes the surface hydrophilic. The photocatalytic activity enhancement and reduced photocorrosion can be achieved because of increased surface area, enhanced hydrophilicity, and the interaction between the metal wire/ZnO and Ag/ZnO heterostructure interface which can improve the charge separation of photogenerated charge carriers. PMID:24997260

  6. Green Synthesis of Ag and Pd Nanospheres, Nanowires, and Nanorods Using Vitamin B 2 : Catalytic Polymerisation of Aniline and Pyrrole

    DOE PAGESBeta

    Nadagouda, Mallikarjuna N.; Varma, Rajender S.

    2008-01-01

    Formore » the first time, we report green chemistry approach using vitamin B 2 in the synthesis of silver (Ag) and palladium (Pd), nanospheres, nanowires, and nanorods at room temperature without using any harmful reducing agents, such as sodium borohydride ( NaBH 4 ) or hydroxylamine hydrochloride and any special capping or dispersing agent. Vitamin B 2 was used as reducing agent as well as capping agent due to its high-water solubility, biodegradability, and low-toxicity compared with other reducing agents. The average particle size of nanoprticle was found to be Ag (average size 6.1 ± 0.1 nm) and Pd (average size 4.1 ± 0.1 nm) nanoparticles in ethylene glycol and Ag (average size 5.9 ± 0.1 nm, and average size 6.1 ± 0.1) nanoparticles in acetic acid and NMP, respectively. The formation of noble multiple shape nanostructures and their self assembly were dependent on the solvent employed for the preparation. When water was used as solvent media, Ag and Pd nanoparticles started to self-assemble into rod-like structures and in isopropanol Ag and Pd nanoparticles yielded wire-like structures with a thickness in the range of 10 to 20 nm and several hundred microns in length. In acetone and acetonitrile medium, the Ag and Pd nanoparticles are self-assembled into a regular pattern making nanorod structures with thicknesses ranging from 100 to 200 nm and lengths of a few microns. The so-synthesized nanostructures were characterized using scanning electron microscopy (SEM), transmission electron microscopy (TEM), energy dispersive X-ray (EDX) analysis, and UV spectroscopy. The ensuing Ag and Pd nanoparticles catalyzed the reactions of aniline and pyrrole to generate polyaniline and polypyrrole nanofibers and may find various technological and biological applications. This single-step greener approach is general and can be extended to other noble metals and transition metal oxides.« less

  7. 3D hierarchical MnO2 nanorod/welded Ag-nanowire-network composites for high-performance supercapacitor electrodes.

    PubMed

    Qiao, Zhensong; Yang, Xiaopeng; Yang, Shuhua; Zhang, Liqiang; Cao, Bingqiang

    2016-06-28

    3D MnO2 nanorod/welded Ag-nanowire-network supercapacitor electrodes were prepared. Welding treatment of the Ag nanowire-network leads to low resistance and long lifetime. Galvanostatic charge/discharge (GCD) induces an ever-lasting morphology changing from flower-like to honeycomb-like for MnO2, which manifests as increasing specific capacitance to 663.4 F g(-1) after 7000 GCD cycles. PMID:27263832

  8. Fabrication and Characterization of ZnO Nanorods on Multiple Substrates.

    PubMed

    Rana, Abu ul Hassan Sarwar; Ko, Kyul; Hong, Sejun; Kang, Mingi; Kim, Hyun-Seok

    2015-11-01

    In this study, we present the fabrication and characterization of ZnO nanorods (NRs) grown on p-Si, gold (Au) and nickel (Ni) coated on Si wafer, indium tin oxide (ITO), and quartz substrates. The aqueous chemical growth method is used for the vertical growth of ZnO NRs on multiple substrates. The samples are characterized with scanning electron microscope and energy dispersive X-ray spectroscopy to probe into the growth, alignment, density, diameter, and length of ZnO NRs on multiple substrates. It is found that under same conditions, like growth temperature, growth time, and solution concentration, ZnO NRs on ITO and quartz have same length but comparatively larger diameter than on other samples. The effects of growth time on the diameter and length of ZnO NRs are also explored. All the samples are characterized with probe station to look at the current-voltage (I-V) behavior of ZnO NRs on multiple substrates. It is found that ZnO NRs on p-Si show a simple p-n heterojunction diode like behavior. ZnO NRs grown on Au- and Ni-coated Si wafers show Schottky I-V characteristic behaviors while ZnO NRs on ITO show a simple ohmic I-V response with comparatively higher level of current. Finally, the I-V response of ZnO NRs on p-Si is also studied under ultraviolet illumination. Because of the photo-generated carriers in ZnO, the sample shows higher level of current upon illumination. PMID:26726520

  9. Near infrared electroluminescence of ZnMgO/InN core-shell nanorod heterostructures grown on Si substrate.

    PubMed

    Wu, Guoguang; Zheng, Weitao; Gao, Fubin; Yang, Hang; Zhao, Yang; Yin, Jingzhi; Zheng, Wei; Li, Wancheng; Zhang, Baolin; Du, Guotong

    2016-07-27

    This paper presents a systematic investigation of a ZnMgO/InN core-shell nanorods heterojunction device on a p-Si substrate. Here we demonstrated the heteroepitaxial growth of the well-aligned ZnMgO/InN core-shell nanorods structure, which enabled an increased heterojunction area to improve the carrier injection efficiency of nanodevices by plasma-assisted molecular beam epitaxy combined with metal-organic chemical vapor deposition. In situ X-ray photoelectron spectroscopy measurements were performed on the ZnMgO nanorods, the interface of ZnMgO/InN and the InN core-shell nanorods to fully understand the structure and working mechanism of the heterojunction device. The current transport mechanism has been discussed in terms of the characteristics of current-voltage and the energy band diagram of the n-InN/ZnMgO/p-Si heterojunction. At a low forward voltage, the current transport followed the dependence of I ∼ V(1.47), which was attributed to the deep-level assisted tunneling. When the forward voltage was larger than 10 V, the current followed the relation of I ∼ V(2) because of the radiative recombination process. In accordance with the above conclusion, the near-infrared electroluminescence of the diode could be observed after the forward bias voltage up to 11.6 V at room temperature. In addition, the size quantization effect and the intrinsic electron accumulation of the InN core-shell nanorods were investigated to explain the blueshift and broadened bandwidth. Furthermore, the light output power of about 0.6 microwatt at a fixed wavelength of 1500 nm indicated that our study will further provide a useful route for realizing the near-infrared electroluminescence of InN on Si substrate. PMID:27418413

  10. Facile Decoration of Polyaniline Fiber with Ag Nanoparticles for Recyclable SERS Substrate.

    PubMed

    Mondal, Sanjoy; Rana, Utpal; Malik, Sudip

    2015-05-20

    Facile synthesis of polyaniline@Ag composite has been successfully demonstrated by a simple solution-dipping method using high-aspect-ratio benzene tetracarboxylic acid-doped polyaniline (BDP) fiber as a nontoxic reducing agent as well as template cum stabilizer. In BDP@Ag composite, BDP fibers are decorated with spherical Ag nanoparticles (Ag NPs), and the population of Ag NPs on BDP fibers is controlled by changing the molar concentration of AgNO3. Importantly, Ag-NP-decorated BDP fibers (BDP@Ag composites) have been evolved as a sensitive materials for the detection of trace amounts of 4-mercaptobenzoic acid and rhodamine 6G as an analyte of surface-enhanced Raman scattering (SERS), and the detection limit is down to nanomolar concentrations with excellent recyclability. Furthermore, synthesized BDP@Ag composites are applied simultaneously as an active SERS substrate and a superior catalyst for reduction of 4-nitrothiophenol. PMID:25912640

  11. Enhanced photoresponse of conformal TiO{sub 2}/Ag nanorod array-based Schottky photodiodes fabricated via successive glancing angle and atomic layer deposition

    SciTech Connect

    Haider, Ali; Biyikli, Necmi; Cansizoglu, Hilal; Cansizoglu, Mehmet Fatih; Karabacak, Tansel; Okyay, Ali Kemal

    2015-01-01

    In this study, the authors demonstrate a proof of concept nanostructured photodiode fabrication method via successive glancing angle deposition (GLAD) and atomic layer deposition (ALD). The fabricated metal-semiconductor nanorod (NR) arrays offer enhanced photoresponse compared to conventional planar thin-film counterparts. Silver (Ag) metallic NR arrays were deposited on Ag-film/Si templates by utilizing GLAD. Subsequently, titanium dioxide (TiO{sub 2}) was deposited conformally on Ag NRs via ALD. Scanning electron microscopy studies confirmed the successful formation of vertically aligned Ag NRs deposited via GLAD and conformal deposition of TiO{sub 2} on Ag NRs via ALD. Following the growth of TiO{sub 2} on Ag NRs, aluminum metallic top contacts were formed to complete the fabrication of NR-based Schottky photodiodes. Nanostructured devices exhibited a photo response enhancement factor of 1.49 × 10{sup 2} under a reverse bias of 3 V.

  12. Color-Controlled Ag Nanoparticles and Nanorods within Confined Mesopores: Microwave-Assisted Rapid Synthesis and Application in Plasmonic Catalysis under Visible-Light Irradiation.

    PubMed

    Mori, Kohsuke; Verma, Priyanka; Hayashi, Ryunosuke; Fuku, Kojirou; Yamashita, Hiromi

    2015-08-10

    Color-controlled spherical Ag nanoparticles (NPs) and nanorods, with features that originate from their particle sizes and morphologies, can be synthesized within the mesoporous structure of SBA-15 by the rapid and uniform microwave (MW)-assisted alcohol reduction method in the absence or presence of surface-modifying organic ligands. The obtained several Ag catalysts exhibit different catalytic activities in the H2 production from ammonia borane (NH3 BH3 , AB) under dark conditions, and higher catalytic activity is observed by smaller yellow Ag NPs in spherical form. The catalytic activities are specifically enhanced under the light irradiation for all Ag catalysts. In particular, under light irradiation, the blue Ag nanorod shows a maximum enhancement of more than twice that observed in the dark. It should be noted that the order of increasing catalytic performance is in close agreement with the order of absorption intensity owing to the Ag localized surface plasmon resonance (LSPR) at irradiation light wavelength. Upon consideration of infrared thermal effect, wavelength dependence on catalytic activity, and effect of radical scavengers, it can be concluded that the dehydrogenation of AB is promoted by change of charge density of the Ag NP surface derived from LSPR. The LSPR-enhanced catalytic activity can be further realized in the tandem reaction consisting of dehydrogenation of AB and hydrogenation of 4-nitrophenol, in which a similar tendency in the enhancement of catalytic activity is observed. PMID:26178067

  13. In situ fabrication of AgI films on various substrates

    SciTech Connect

    Zheng, Z. Liu, A.R.; Wang, S.M.; Huang, B.J.; Ma, X.M.; Zhao, H.X.; Li, D.P.; Zhang, L.Z.

    2008-08-04

    A facile solution-phase chemical route is developed to directly construct silver iodide (AgI) films/crystals on various substrates including silver foil, silicon wafer and glass, etc. The resulting AgI films were characterized by X-ray diffraction (XRD), scanning electron microscope (SEM) and X-ray photoelectron spectroscopy (XPS). The AgI films with different morphologies can be obtained by controlling the reaction parameters. This method is a simple and fast way for in situ deposition of AgI crystals/films on different substrates. These films may be applied in chemical sensing systems and solid-state batteries as solid electrolytes.

  14. Transparent Conductive AGZO/Ag/AGZO Multilayers on PET Substrate by Roll-to-Roll Sputtering.

    PubMed

    Kim, Taehoon; Park, Kwangwon; Kim, Jongsu

    2016-02-01

    Indium-free Al and Ga-codoped ZnO (AGZO) multilayer films with nanoscale Ag interlayer were deposited by dual target roll-to-roll RF for AGZO and DC sputtering systems for Ag at room temperature for a large scale. The thicknesses of AGZO/Ag/AGZO multilayer were optimized by changing the roll speed: 0.15/1.1/0.15 m/min for AGZO/Ag/AGZO multilayers, respectively. The optimum thicknesses of AGZO/Ag/AGZO multilayer are 9.21, 8.32 and 8.04 nm, respectively. Optimized AGZO/Ag/AGZO multilayer films showed an excellent transparency (84% at 550 nm) and a low sheet resistance (9.2 omega/sq.) on PET substrates for opto-electronic applications. The effects of nanoscale Ag interlayer on optical and electrical properties of AGZO/Ag/AGZO multilayer films were discussed. PMID:27433648

  15. Constructing n-ZnO@Au heterogeneous nanorod arrays on p-Si substrate as efficient photocathode for water splitting.

    PubMed

    Bao, Zhijia; Xu, Xiaoyong; Zhou, Gang; Hu, Jingguo

    2016-07-29

    Developing ingenious heterostructure photoelectrodes in photoelectrochemical (PEC) cells to both harvest more solar photons and steer desired charge separation flow is a prerequisite challenge for PEC water splitting. Herein a hierarchical p-Si/n-ZnO@Au heterostructure was constructed via large-area growth of one-dimensional (1D) ZnO nanorod arrays (NRAs) on p-Si substrate followed by decorating with Au nanoparticles (NPs), which exhibited remarkably improved photocathode activity for PEC water splitting relative to the bare Si and Si/ZnO NRAs photocathodes. In addition to structural superiorities of 1D NRAs, a series of dynamic contributions from complementary band-gap structure, p-n heterojunctions and Au plasmon towards photon harvesting and charge separation were demonstrated to ensure a well-steered collection of photoelectrons at the exposed ZnO nanorods and Au NPs, enabling substantially improved photocathode performance. PMID:27306198

  16. Constructing n-ZnO@Au heterogeneous nanorod arrays on p-Si substrate as efficient photocathode for water splitting

    NASA Astrophysics Data System (ADS)

    Bao, Zhijia; Xu, Xiaoyong; Zhou, Gang; Hu, Jingguo

    2016-07-01

    Developing ingenious heterostructure photoelectrodes in photoelectrochemical (PEC) cells to both harvest more solar photons and steer desired charge separation flow is a prerequisite challenge for PEC water splitting. Herein a hierarchical p-Si/n-ZnO@Au heterostructure was constructed via large-area growth of one-dimensional (1D) ZnO nanorod arrays (NRAs) on p-Si substrate followed by decorating with Au nanoparticles (NPs), which exhibited remarkably improved photocathode activity for PEC water splitting relative to the bare Si and Si/ZnO NRAs photocathodes. In addition to structural superiorities of 1D NRAs, a series of dynamic contributions from complementary band-gap structure, p–n heterojunctions and Au plasmon towards photon harvesting and charge separation were demonstrated to ensure a well-steered collection of photoelectrons at the exposed ZnO nanorods and Au NPs, enabling substantially improved photocathode performance.

  17. Mechanical and piezoelectric properties of zinc oxide nanorods grown on conductive textile fabric as an alternative substrate

    NASA Astrophysics Data System (ADS)

    Khan, Azam; Hussain, Mushtaque; Nur, Omer; Willander, Magnus

    2014-08-01

    The present research is devoted to understanding the mechanism and causes of variation in the piezoelectric potential generated from vertically aligned zinc oxide (ZnO) nanorods (NRs), which were grown on a conductive textile fabric as an alternative substrate by using the aqueous chemical growth method. The piezoelectric voltage was harvested from vertically aligned ZnO NRs having different physical parameters by using atomic force microscopy in contact mode and the variation in the generated piezoelectricity was investigated. The generated output potential indicates that different physical parameters such aspect ratio, crystal size and lattice internal crystal strain have a strong influence on the piezoelectric properties of vertically aligned ZnO NRs, which were grown on a textile fabric. Presented results indicate that textiles can be used as an alternative substrate just like the other conventional substrates, because our results are similar/better than many reported works on conventional substrates.

  18. Fabrication of pure and Ag-doped TiO2 nanorods and study of the lattice strain and the activation energy of the crystalline phases

    NASA Astrophysics Data System (ADS)

    Riazian, Mehran; Rad, Shima Daliri; Azinabadi, Reza Ramezani

    2013-02-01

    TiO2 nanorods can be used as dye-sensitized solar cells and as various sensors and photocatalysts. These nanorods are synthesized by using a thermal corrosion process in a NaOH solution at 200 °C with TiO2 powder as a source material. In the present work, the synthesis of TiO2 nanorods in anatase, rutile and Ti8O15 phases and the synthesis of TiO2 nanorods by using the sol-gel method and alkaline corrosion to incorporate silver and silver-oxide dopants are reported. The morphologies and the crystalline structures of the TiO2 nanorods are characterized using field emission scanning electron microscopy (FE-SEM), atomic force microscopy (AFM), tunneling electron microscopy (TEM) and X-ray diffraction (XRD) techniques. The obtained results show an aggregation structure at high calcining temperatures with spherical particles and with Ti-O-Ti, Ti-O and Ag-O bonds. The effects of the chemical composition and the calcining temperature on the surface topography, lattice strain and phase crystallization are studied. The activation energy (E) of nanoparticle formation in a pure state during thermal treatment is calculated.

  19. Multishell Au/Ag/SiO2 nanorods with tunable optical properties as single particle orientation and rotational tracking probes

    SciTech Connect

    Chen, Kuangcai; Lin, Chia -Cheng; Vela, Javier; Fang, Ning

    2015-04-07

    In this study, three-layer core–shell plasmonic nanorods (Au/Ag/SiO2–NRs), consisting of a gold nanorod core, a thin silver shell, and a thin silica layer, were synthesized and used as optical imaging probes under a differential interference contrast microscope for single particle orientation and rotational tracking. The localized surface plasmon resonance modes were enhanced upon the addition of the silver shell, and the anisotropic optical properties of gold nanorods were maintained. The silica coating enables surface functionalization with silane coupling agents and provides enhanced stability and biocompatibility. Taking advantage of the longitudinal LSPR enhancement, the orientation and rotational information of the hybrid nanorods on synthetic lipid bilayers and on live cell membranes were obtained with millisecond temporal resolution using a scientific complementary metal-oxide-semiconductor camera. The results demonstrate that the as-synthesized hybrid nanorods are promising imaging probes with improved sensitivity and good biocompatibility for single plasmonic particle tracking experiments in biological systems.

  20. Structural and Critical Behaviors of Ag Rough Films Deposited on Liquid Substrates

    NASA Astrophysics Data System (ADS)

    Ye, Gao-xiang; Feng, Chun-mu; Zhang, Qi-rui; Ge, Hong-liang; Zhang, Xuan-jia

    1996-10-01

    A new Ag rough film system, deposited on silicone oil surfaces by rf-magnetron sputtering method, has been fabricated. The chrysanthemum-like surface morphology at micron length scale is observed. It is proposed that the anomalous critical behavior mainly results from the relative shift between the Ag atom clusters and the substrate. The discussion of the deposition mechanism is also presented.

  1. Platinum-coated porous gold nanorods in methanol electrooxidation: dependence of catalytic activity on ligament size.

    PubMed

    Yoo, Sang-Hoon; Liu, Lichun; Cho, Sang Hyun; Park, Sungho

    2012-12-01

    Here we demonstrate that, in the dealloying process of Au-Ag nanorods, temperature is the key parameter for producing porous Au nanorods with tunable ligament sizes. The vertically aligned Au-Ag alloy nanorods were first synthesized by the electrochemical co-deposition of Au and Ag onto anodic aluminum oxide (AAO) membrane templates. Porous Au nanorods were then obtained by selectively etching Ag away from the precursor Au-Ag alloy nanorods. Control of the ligament size was achieved by controlling the dealloying temperature. Pt deposited on the porous Au nanorods with smaller ligaments exhibited a higher catalytic activity during methanol electrooxidation than those deposited on nanorods with larger ligaments produced by dealloying at higher temperatures. The strong dependence of the catalytic activity on the ligament size of porous Au is principally due to different amounts of carbon monoxide (CO) generated during methanol electrooxidation. Less CO was generated as the ligament size decreased. This finding is of importance for developing highly efficient cathode materials for carrying out methanol electrooxidation in practical applications in which porous Au with a large surface area is used as a supporting substrate. PMID:23023934

  2. Plasmon enhanced CdS-quantum dot sensitized solar cell using ZnO nanorods array deposited with Ag nanoparticles as photoanode

    NASA Astrophysics Data System (ADS)

    Eskandari, M.; Ahmadi, V.; Yousefi rad, M.; Kohnehpoushi, S.

    2015-04-01

    CdS-quantum dot sensitized solar cell using ZnO nanorods (ZnO NRs) array deposited with Ag nanoparticles (Ag NPs) as photoanode was fabricated. Light absorption effect of Ag NPs on improvement of the cell performance was investigated. Performance improvement of metal nanoparticles (MNPs) was controlled by the structure design and architecture. Different decorations and densities of Ag NPs were utilized on the photoanode. Results showed that using 5% Ag NPs in the photoanode results in the increased efficiency, fill factor, and circuit current density from 0.28% to 0.60%, 0.22 to 0.29, and 2.18 mA/cm2 to 3.25 mA/cm2, respectively. Also, incident photon-to-current efficiencies (IPCE) results showed that cell performance improvement is related to enhanced absorption in the photoanode, which is because of the surface plasmonic resonance and light scattering of Ag NPs in the photoanode. Measurements of electrochemical impedance spectroscopy revealed that hole transfer kinetics increases with introduction of Ag NPs into photoanode. Also, it is shown that chemical capacitance increases with introduction of Ag NPs. Such increase can be attributed to the surface palsmonic resonance of Ag NPs which leads to absorption of more light in the photoanode and generation of more photoelectron in the photoanode.

  3. Effects of the geometries of micro-scale substrates on the surface morphologies of ZnO nanorod-based hierarchical structures

    NASA Astrophysics Data System (ADS)

    Jing, Weixuan; Qi, Han; Shi, Jiafan; Jiang, Zhuangde; Zhou, Fan; Cheng, Yanyan; Gao, Kun

    2015-11-01

    This paper identifies and investigates the influencing factors and their effects on the surface morphologies of ZnO nanorod-based hierarchical structures. With ZnO nanorods hydrothermally synthesized on a piece of planar glass, an optical fiber core, and a SiO2 microsphere, three kinds of ZnO nanorod-based hierarchical structures were fabricated. It is found that not only the synthesizing parameters but also the geometries of the micro-scale substrates affect significantly the nucleation densities of seed layers and the Zn2+ diffusion zones of growth solution upon the substrate surfaces. These two factors further give rise to varied diameters and orientation of the ZnO nanorods as well as different sizes of the pits among the bundles of ZnO nanorods, which eventually result in different surface morphologies of corresponding hierarchical structures. With Zn2+ concentration of the growth solution increasing, side-by-side coalescence among neighboring ZnO nanorods first appears on the optical fiber core. The different curvature radii of the optical fiber core at front and side view lead to the anisotropic surface morphology of the related hierarchical structure. Although their curvature radii are the same, the different geometries of the optical fiber core at side view and the planar glass account for varied surface morphologies of the corresponding hierarchical structures.

  4. Highly sensitive and simple SERS substrate based on photochemically generated carbon nanotubes-gold nanorods hybrids.

    PubMed

    Caires, A J; Vaz, R P; Fantini, C; Ladeira, L O

    2015-10-01

    We report a simple and easy formation of hybrids between multi-wall carbon nanotubes and gold nanorods by one-pot in situ photochemical synthesis. Measurements of surface-enhanced Raman scattering (SERS) through the effect "coffee ring" in visible and near infrared (NIR) show high sensitivity with detection of nanomolar concentrations of aromatic dyes. The formation of nanocomposites between carbon nanotubes and gold nanorods without chemical binders simplifies the preparation. Photochemical synthesis is an advance over the techniques previously published. PMID:26057106

  5. Substrate-Oriented Nanorod Scaffolds in Polymer–Fullerene Bulk Heterojunction Solar Cells

    PubMed Central

    Ogawa, Yuta; White, Matthew S; Sun, Lina; Scharber, Markus C; Sariciftci, Niyazi Serdar; Yoshida, Tsukasa

    2014-01-01

    The use of a p-type inorganic semiconductor to form a nanorod scaffold within a polymer-fullerene bulk heterojunction solar cell is reported. The performance of this cell is compared to those made of the commonly used n-type scaffold of ZnO, which has been reported many times in the literature. The scaffold is designed to improve charge-carrier collection by increased mobility in thicker samples. Observations show that generally the device performance shows a negative correlation to nanorod length. By using CuSCN as a p-type inorganic scaffold, a very similar trend is observed. PMID:24652668

  6. Reproducible and recyclable SERS substrates: Flower-like Ag structures with concave surfaces formed by electrodeposition

    NASA Astrophysics Data System (ADS)

    Bian, Juncao; Shu, Shiwei; Li, Jianfu; Huang, Chao; Li, Yang Yang; Zhang, Rui-Qin

    2015-04-01

    Direct synthesis of three-dimensional Ag structures on solid substrates for the purposes of producing reproducible and recyclable surface-enhanced Raman scattering (SERS) applications remains challenging. In this work, flower-like Ag structures with concave surfaces (FACS) were successfully electrodeposited onto ITO glass using the double-potentiostatic method. The FACS, with an enhancement factor of the order of 108, exhibited a SERS signal intensity 3.3 times stronger than that measured from Ag nanostructures without concave surfaces. A cleaning procedure involving lengthy immersion of the sample in ethanol and KNO3 was proposed to recycle the substrate and confirmed by using rhodamine 6G, adenine, and 4-aminothiophenol as target molecules. The findings can help to advance the practical applications of Ag nanostructure-based SERS substrates.

  7. Fractal structure formation from Ag nanoparticle films on insulating substrates.

    PubMed

    Tang, Jing; Li, Zhiyong; Xia, Qiangfei; Williams, R Stanley

    2009-07-01

    Two dimensional (2D) fractal structures were observed to form from fairly uniform Ag island films (equivalent mass thicknesses of 1.5 and 5 nm) on insulating silicon dioxide surfaces (thermally grown silicon oxide on Si or quartz) upon immersion in deionized water. This result is distinctly different from the previously observed three-dimensional (3D) growth of faceted Ag nanocrystals on conductive surfaces (ITO and graphite) as the result of an electrochemical Ostwald ripening process, which also occurs on native oxide covered silicon surfaces as reported here. The fractal structures formed by diffusion-limited aggregation (DLA) of Ag species on the insulating surfaces. We present the experimental observation of this phenomenon and discuss some possible mechanisms for the DLA formation. PMID:19496573

  8. Fabrication of highly homogeneous surface-enhanced Raman scattering substrates using Ag ion implantation

    NASA Astrophysics Data System (ADS)

    Li, Wenqing; Xiao, Xiangheng; Dai, Zhigao; Wu, Wei; Cheng, Li; Mei, Fei; Zhang, Xingang; Jiang, Changzhong

    2016-06-01

    In recent times, surface-enhanced Raman scattering (SERS) has attracted attention for its excellent potential application in chemical and biological detection. In this work, we demonstrate that a highly homogeneous SERS substrate can be realized by Ag ion implantation and the subsequent annealing process. Both the implantation and annealing parameters have been optimized for a high sensitivity SERS substrate. The SERS measurement indicates that a sample implanted by 20 kV Ag ions with a dosage of 3  ×  1016 ions cm‑2 exhibits the highest SERS activity. In addition, the SERS activity of the Ag-implanted substrates depends highly on the annealing temperature and time. Since none of the fabrication processes contain chemical reactions, our substrate is a clean system without any chemical residues.

  9. Laser-nanostructured Ag films as substrates for surface-enhanced Raman spectroscopy

    SciTech Connect

    Henley, S.J.; Carey, J.D.; Silva, S.R.P.

    2006-02-20

    Pulsed-laser (248 nm) irradiation of Ag thin films was employed to produce nanostructured Ag/SiO{sub 2} substrates. By tailoring the laser fluence, it was possible to controllably adjust the mean diameter of the resultant near-spherical Ag droplets. Thin films of tetrahedral amorphous carbon (ta-C) were subsequently deposited onto the nanostructured substrates. Visible Raman measurements were performed on the ta-C films, where it was observed that the intensity of the Raman signal was increased by nearly two orders of magnitude, when compared with ta-C films grown on nonstructured substrates. The use of laser annealing as a method of preparing substrates, at low macroscopic temperatures, for surface-enhanced Raman spectroscopy on subnanometer-thick films is discussed.

  10. Fabrication of highly homogeneous surface-enhanced Raman scattering substrates using Ag ion implantation.

    PubMed

    Li, Wenqing; Xiao, Xiangheng; Dai, Zhigao; Wu, Wei; Cheng, Li; Mei, Fei; Zhang, Xingang; Jiang, Changzhong

    2016-06-29

    In recent times, surface-enhanced Raman scattering (SERS) has attracted attention for its excellent potential application in chemical and biological detection. In this work, we demonstrate that a highly homogeneous SERS substrate can be realized by Ag ion implantation and the subsequent annealing process. Both the implantation and annealing parameters have been optimized for a high sensitivity SERS substrate. The SERS measurement indicates that a sample implanted by 20 kV Ag ions with a dosage of 3  ×  10(16) ions cm(-2) exhibits the highest SERS activity. In addition, the SERS activity of the Ag-implanted substrates depends highly on the annealing temperature and time. Since none of the fabrication processes contain chemical reactions, our substrate is a clean system without any chemical residues. PMID:27167880

  11. Measuring the Optical Absorption Cross-sections of Au-Ag Nanocages and Au Nanorods by Photoacoustic Imaging

    PubMed Central

    Cho, Eun Chul; Kim, Chulhong; Zhou, Fei; Cobley, Claire M.; Song, Kwang Hyun; Chen, Jingyi; Li, Zhi-Yuhan; Wang, Lihong V.; Xia, Younan

    2009-01-01

    This paper presents a method for measuring the optical absorption cross-sections (σa) of Au-Ag nanocages and Au nanorods. The method is based on photoacoustic (PA) imaging, where the detected signal is directly proportional to the absorption coefficient (μa) of the nanostructure. For each type of nanostructure, we firstly obtained μa from the PA signal by benchmarking against a linear calibration curve (PA signal vs. μa) derived from a set of methylene blue solutions with different concentrations. We then calculated σa by dividing the μa by the corresponding concentration of the Au nanostructure. Additonally, we obtained the extinction cross-section (σe, sum of absorption and scattering) from the extinction spectrum recorded using a conventional UV-vis-NIR spectrometer. From the measurements of σa and σe, we were able to easily derive both the absorption and scattering cross-sections for each type of gold nanostructure. The ratios of absorption to extinction obtained from experimental and theoretical approaches agreed well, demonstrating the potential use of this method in determining the optical absorption and scattering properties of gold nanostructures and other types of nanomaterials. PMID:19680423

  12. Surfactant role of Ag atoms in the growth of Si layers on Si(111)√3×√3-Ag substrates

    SciTech Connect

    Yamagami, Tsuyoshi; Sone, Junki; Nakatsuji, Kan; Hirayama, Hiroyuki

    2014-10-13

    The growth of Si layers on Si(111)√3×√3-Ag substrates was studied for coverages of up to a few mono-layers. Atomically flat islands were observed to nucleate in the growth at 570 K. The top surfaces of the islands were covered in Ag atoms and exhibited a √3×√3 reconstruction with the same surface state dispersions as Si(111)√3×√3-Ag substrates. These results indicate that the Ag atoms on the substrate always hop up to the top of the Si layers.

  13. Immobilization of gold nanorods onto electrospun polycaprolactone fibers via polyelectrolyte decoration--a 3D SERS substrate.

    PubMed

    Tang, Wenqiong; Chase, D Bruce; Rabolt, John F

    2013-11-19

    We report the fabrication of a homogeneous and highly dense gold nanorod (AuNR) assembly on electrospun polycaprolactone (PCL) fibers using electrostatic interaction as the driving force. Specifically, decoration of a poly(sodium 4-styrenesulfonate) (PSS) layer onto the AuNRs imposed negative charges on the nanorod surface, and the interactions between PSS and the AuNRs were investigated using attenuated total reflection Fourier transform infrared spectroscopy (ATR-FTIR). Positive charges on the PCL fibrous substrate were established via polyelectrolyte layer-by-layer deposition, which was investigated using multiple characterization techniques. Driven by the attractive electrostatic interaction, immobilization of AuNRs on the PCL fibers was initiated upon substrate immersion, and the kinetics of the immobilization process were studied using UV-vis spectroscopy. Electron microscopy characterization of the AuNR/PCL nanocomposite fibers reveals a uniform AuNR coating on the fiber surface with the immobilized AuNR density being high enough to provide full surface coverage. By using both 4-mercaptopyridine and Rhodamine 6G as probe molecules, the performance of the AuNR/PCL fibrous mesh as a three-dimensional (3D) surface-enhanced Raman scattering (SERS) substrate was investigated. The nanocomposite fibers allowed detection at concentrations as low as 10(-7) M of the probe molecule in solution and exhibited excellent reproducibility in the SERS measurements. In addition, a comparison between the 3D AuNR/PCL fibrous mesh and a 2D AuNR/PCL film reveals that the enhanced surface area in the 3D substrate effectively improved the SERS performance with a 6-fold increase in the Raman intensity. PMID:24138084

  14. Relationship between surface structure and one-dimensional nanorod growth in ErBa2Cu307-δ films on vicinal SrTi03 substrates

    NASA Astrophysics Data System (ADS)

    Kai, Hideki; Ichinose, Ataru; Horii, Shigeru; Yoshida, Yutaka; Kita, Ryusuke; Matsumoto, Kaname; Teranishi, Ryo; Mori, Nobuyuki; Mukaida, Masashi

    2010-06-01

    Effects of vicinal growth in ErBa2Cu307-δ (ErBCO) with one-dimensional nanorods are discussed from their microstructures. BaNb2O6 doped ErBCO films were grown on vicinal substrates with tilted angles of 0°, 4° and 8° by a pulsed laser technique. Surface step structure appeared distinctly with increasing vicinal angles to 8° in images of scanning electron microscopy and atomic force microscopy. Then, Ba(Er0.5Nb0.5)O3 nanorods continuously grew from the step on vicinal substrate to film surface steps in transmission electron microscopy images of the film. The alignment of one-dimensional nanorods relate closely to film growth morphology.

  15. Role of Ag2S coupling on enhancing the visible-light-induced catalytic property of TiO2 nanorod arrays

    PubMed Central

    Li, Zhengcao; Xiong, Shan; Wang, Guojing; Xie, Zheng; Zhang, Zhengjun

    2016-01-01

    In order to obtain a better photocatalytic performance under visible light, Ag2S-coupled TiO2 nanorod arrays (NRAs) were prepared through the electron beam deposition with glancing angle deposition (GLAD) technique, annealing in air, followed by the successive ionic layer absorption and reaction (SILAR) method. The properties of the photoelectrochemical and photocatalytic degradation of methyl orange (MO) were thus conducted. The presence of Ag2S on TiO2 NRAs was observed to have a significant improvement on the response to visible light. It’s resulted from that Ag2S coupling can improve the short circuit photocurrent density and enhance the photocatalytic activity remarkably. PMID:26790759

  16. Growth and characterization of rutile TiO2 nanorods on various substrates with fabricated fast-response metal-semiconductor-metal UV detector based on Si substrate

    NASA Astrophysics Data System (ADS)

    Selman, Abbas M.; Hassan, Z.

    2015-07-01

    Rutile-phase titanium dioxide nanorods (NRs) were synthesized successfully on p-type silicon (Si) (1 1 1), c-plane sapphire (Al2O3), glass coated with fluorine-doped tin oxide (FTO), glass, and quartz substrates via chemical bath deposition method. All substrates were seeded with a TiO2 seed layer synthesized with a radio frequency reactive magnetron sputtering system prior to NRs growth. The effect of substrate type on structural, morphological, and optical properties of rutile TiO2 NRs was studied. X-ray diffraction, Raman spectroscopy, and field-emission scanning electron microscopy analyses showed the tetragonal rutile structure of the synthesized TiO2 NRs. Optical properties were examined with photoluminescence (PL) spectroscopy of the grown rutile NRs on all substrates, with the spectra exhibiting one strong ultraviolet emission peak intensity compared with broad visible peak. The optimal sample of rutile NRs was grown on Si substrate. Thus, a fast-response metal-semiconductor-metal ultraviolet (UV) detector was fabricated. Upon exposure to 365 nm light (2.3 mW/cm2) at 5 V bias, the device displays 2.62 × 10-5 A photocurrent, and the response and recovery times are calculated as 18.5 and 19.1 ms, respectively. These results demonstrate that the fabricated high-quality photodiode is a promising candidate as a low-cost UV photodetector for commercially integrated photoelectronic applications.

  17. Growth of the [110] oriented TiO2 nanorods on ITO substrates by sputtering technique for dye-sensitized solar cells

    NASA Astrophysics Data System (ADS)

    Meng, Lijian; Chen, Hong; Li, Can; Dos Santos, Manuel

    2014-09-01

    TiO2 films have been deposited on ITO substrates by dc reactive magnetron sputtering technique. It has been found that the sputtering pressure is a very important parameter for the structure of the deposited TiO2 films. When the pressure is lower than 1 Pa, the deposited film has a dense structure and shows a preferred orientation along the [101] direction. However, the nanorod structure has been obtained as the sputtering pressure is higher than 1 Pa. These nanorods structure TiO2 film shows a preferred orientation along the [110] direction. The phases of the deposited TiO2 films have been characterized by the x-ray diffraction and the Raman scattering measurements. All the films show an anatase phase and no other phase has been observed. The results of the SEM show that these TiO2 nanorods are perpendicular to the ITO substrate. The TEM measurement shows that the nanorods have a very rough surface. The dye-sensitized solar cells (DSSCs) have been assembled using these TiO2 nanorod films prepared at different sputtering pressures as photoelectrode. And the effect of the sputtering pressure on the properties of the photoelectric conversion of the DSSCs has been studied.

  18. Exploring Ag(111) Substrate for Epitaxially Growing Monolayer Stanene: A First-Principles Study

    NASA Astrophysics Data System (ADS)

    Gao, Junfeng; Zhang, Gang; Zhang, Yong-Wei

    2016-07-01

    Stanene, a two-dimensional topological insulator composed of Sn atoms in a hexagonal lattice, is a promising contender to Si in nanoelectronics. Currently it is still a significant challenge to achieve large-area, high-quality monolayer stanene. We explore the potential of Ag(111) surface as an ideal substrate for the epitaxial growth of monolayer stanene. Using first-principles calculations, we study the stability of the structure of stanene in different epitaxial relations with respect to Ag(111) surface, and also the diffusion behavior of Sn adatom on Ag(111) surface. Our study reveals that: (1) the hexagonal structure of stanene monolayer is well reserved on Ag(111) surface; (2) the height of epitaxial stanene monolayer is comparable to the step height of the substrate, enabling the growth to cross the surface step and achieve a large-area stanene; (3) the perfect lattice structure of free-standing stanene can be achieved once the epitaxial stanene monolayer is detached from Ag(111) surface; and finally (4) the diffusion barrier of Sn adatom on Ag(111) surface is found to be only 0.041 eV, allowing the epitaxial growth of stanene monolayer even at low temperatures. Our above revelations strongly suggest that Ag(111) surface is an ideal candidate for growing large-area, high-quality monolayer stanene.

  19. Exploring Ag(111) Substrate for Epitaxially Growing Monolayer Stanene: A First-Principles Study.

    PubMed

    Gao, Junfeng; Zhang, Gang; Zhang, Yong-Wei

    2016-01-01

    Stanene, a two-dimensional topological insulator composed of Sn atoms in a hexagonal lattice, is a promising contender to Si in nanoelectronics. Currently it is still a significant challenge to achieve large-area, high-quality monolayer stanene. We explore the potential of Ag(111) surface as an ideal substrate for the epitaxial growth of monolayer stanene. Using first-principles calculations, we study the stability of the structure of stanene in different epitaxial relations with respect to Ag(111) surface, and also the diffusion behavior of Sn adatom on Ag(111) surface. Our study reveals that: (1) the hexagonal structure of stanene monolayer is well reserved on Ag(111) surface; (2) the height of epitaxial stanene monolayer is comparable to the step height of the substrate, enabling the growth to cross the surface step and achieve a large-area stanene; (3) the perfect lattice structure of free-standing stanene can be achieved once the epitaxial stanene monolayer is detached from Ag(111) surface; and finally (4) the diffusion barrier of Sn adatom on Ag(111) surface is found to be only 0.041 eV, allowing the epitaxial growth of stanene monolayer even at low temperatures. Our above revelations strongly suggest that Ag(111) surface is an ideal candidate for growing large-area, high-quality monolayer stanene. PMID:27373464

  20. Exploring Ag(111) Substrate for Epitaxially Growing Monolayer Stanene: A First-Principles Study

    PubMed Central

    Gao, Junfeng; Zhang, Gang; Zhang, Yong-Wei

    2016-01-01

    Stanene, a two-dimensional topological insulator composed of Sn atoms in a hexagonal lattice, is a promising contender to Si in nanoelectronics. Currently it is still a significant challenge to achieve large-area, high-quality monolayer stanene. We explore the potential of Ag(111) surface as an ideal substrate for the epitaxial growth of monolayer stanene. Using first-principles calculations, we study the stability of the structure of stanene in different epitaxial relations with respect to Ag(111) surface, and also the diffusion behavior of Sn adatom on Ag(111) surface. Our study reveals that: (1) the hexagonal structure of stanene monolayer is well reserved on Ag(111) surface; (2) the height of epitaxial stanene monolayer is comparable to the step height of the substrate, enabling the growth to cross the surface step and achieve a large-area stanene; (3) the perfect lattice structure of free-standing stanene can be achieved once the epitaxial stanene monolayer is detached from Ag(111) surface; and finally (4) the diffusion barrier of Sn adatom on Ag(111) surface is found to be only 0.041 eV, allowing the epitaxial growth of stanene monolayer even at low temperatures. Our above revelations strongly suggest that Ag(111) surface is an ideal candidate for growing large-area, high-quality monolayer stanene. PMID:27373464

  1. The role of seeding in the morphology and wettability of ZnO nanorods films on different substrates

    NASA Astrophysics Data System (ADS)

    Rodríguez, Juan; Onna, Diego; Sánchez, Luis; Marchi, M. Claudia; Candal, Roberto; Ponce, Silvia; Bilmes, Sara A.

    2013-08-01

    Spray pyrolysis (SP) and spray-gel (SG) techniques were used to deposit ZnO seeds on Fluor doped tin oxide glasses (FTO), heated at 350 °C or 130 °C, and PET heated at 90 °C. The effect of seeding on the morphology and wettability of ZnO nanorods (NRs) films grown by wet chemical methods was analyzed. The morphology and wettability of ZnO NRs films depend on the seeding process. SP seeds formed from zinc acetate dissolved in water ethanol mixtures yield vertically aligned ZnO NRs, whose diameters and dispersion size are determined by the ethanol/water ratio in the precursor solution. SG seeds formed from a methanol ZnO sol produce a ring patterned distribution on the FTO substrate. The drying of ZnO sol drops impinging on the substrate produces high density of seeds along a ring yielding textured films with NRs vertically oriented on the rings and multi-oriented outside them. This effect was not observed when ZnO NRs grown onto the ZnO/PET substrate, however rod diameter is related with the density of seeds. This way to control the density and diameter of NRs deposited onto a substrate modify the wettability and opens new possibilities for the design of tailored nanomaterials for photochemical applications. Both type of NRs films showed a strong luminescence emission in the UV and in the blue, associated with surface and intrinsic defects.

  2. Photoelectrochemical characteristics of TiO2 nanorod arrays grown on fluorine doped tin oxide substrates by the facile seeding layer assisted hydrothermal method

    NASA Astrophysics Data System (ADS)

    Sui, Mei-rong; Han, Cui-ping; Gu, Xiu-quan; Wang, Yong; Tang, Lu; Tang, Hui

    2016-05-01

    TiO2 nanorod arrays (NRAs) were prepared on fluorine doped tin oxide (FTO) substrates by a facile two-step hydrothermal method. The nanorods were selectively grown on the FTO regions which were covered with TiO2 seeding layer. It took 5 h to obtain the compact arrays with the nanorod length of ~2 μm and diameter of ~50 nm. The photoelectrochemical (PEC) properties of TiO2 NRAs are also investigated. It is demonstrated that the TiO2 NRAs indicate the good photoelectric conversion ability with an efficiency of 0.22% at a full-wavelength irradiation. A photocurrent density of 0.21 mA/cm2 is observed at 0.7 V versus the saturated calomel electrode (SCE). More evidences suggest that the charge transferring resistance is lowered at an irradiation, while the flat-band potential ( V fb) is shifted towards the positive side.

  3. Preparation and Photovoltaic Properties of Dye Sensitized Solar Cells Using ZnO Nanorods Stacking Films on AZO Substrate as Photoanode.

    PubMed

    Xu, Yang; Wang, Xina; Liu, Rong; Wang, Hao

    2016-04-01

    Three-dimensional stacking of ZnO nanorods on conducting aluminum-doped ZnO (AZO) glass were studied as efficient photoanodes of dye sensitized solar cells (DSSCs). By changing hydrothermal growth time and cycle times, the thickness of ZnO nanorods stacking films varied from 30 µm to 64 µm, and its influence on the energetic conversion efficiency of the DSSCs based on the stacking films photoanodes was investigated. The loading density of N719 on the surface of ZnO nanorods was studied to increase the efficiency of the cells. Annealing experiments showed that the AZO substrates remained good conductors until heated above 350 °C. A photoelectric conversion efficiency as high as ~2.0% together with ISC of ~9.5 mA/cm2, VOC of ~0.5 V and FF of ~41.4% was achieved for the DSSC using 50 µm-thick film stacking by ZnO nanorods as photoanode and N719 as sensitizer under illumination of AM1.5G solar light (power density of 100 mW/cm2). A charge separation and transfer mechanism was proposed for the ZnO nanorods stacking electrode-based DSSCs. PMID:27451677

  4. Resonant surface enhancement of Raman scattering of Ag nanoparticles on silicon substrates fabricated by dc sputtering

    SciTech Connect

    Fang Yingcui; Li Xiaxi; Blinn, Kevin; Mahmoud, Mahmoud A.; Liu Meilin

    2012-09-15

    Ag nanoparticles (AgNPs) were deposited onto silicon substrates by direct current (dc) magnetron sputtering. The influences of sputtering power and sputtering time on the AgNP film morphology were studied using atomic force microscopy. The particle size was successfully tuned from 19 nm to 53 nm by varying the sputtering time at a dc power of 10 W. When Rhodamine 6 G (R6G) was used as the probe molecule, the AgNP films showed significant surface enhanced Raman scattering effect. In particular, it is found that larger particles show stronger enhancement for lower concentrations of R6G while smaller particles display stronger enhancement for higher concentrations of R6G.

  5. Au@Ag Heterogeneous Nanorods as Nanozyme Interfaces with Peroxidase-Like Activity and Their Application for One-Pot Analysis of Glucose at Nearly Neutral pH.

    PubMed

    Han, Lei; Li, Cuncheng; Zhang, Tao; Lang, Qiaolin; Liu, Aihua

    2015-07-01

    As substitutes for natural peroxidases, most nanomaterial-based enzyme mimetics (nanozymes) have unique properties such as high stability, low-cost, large surface area, and high catalytic activity. However, they usually work in acidic conditions and thus impede their real applications. In this work, by modulating the nanostructure, composition, and surface property of the bimetallic materials, the positively charged poly(diallyldimethylammonium)-stabilized Au@Ag heterogeneous nanorods (NRs) were developed as synergistic peroxidase-like interfaces, which exhibited high activity over a wide pH range (pH 4.0-6.5) using 2,2'-azino-bis(3-ethylbenzthiazoline-6-sulfonic acid) diammonium salt (ABTS) as the chromogenic substrate. At pH 6.5, the peroxidase-like activity for the Au@Ag heterogeneous NRs was stable and optimal within 20-40 °C. Moreover, the Au@Ag heterogeneous NRs showed excellent temperature stability and long-term storage stability. Given these characters, the detection of H2O2 at pH 6.5 was proposed on the basis of the Au@Ag heterogeneous NRs catalyzing the colorimetric reaction of H2O2 and ABTS, where the oxidized ABTS showed a typical absorption peak at 414 nm. The absorbance at 414 nm was linear with H2O2 concentration from 0.01 to 10 mM. Further, considering that Au@Ag heterogeneous NRs and glucose oxidase (GOx) have similar optimal pH for catalytic activities, a novel one-pot method for the detection of glucose was developed by the coupled catalytic reaction using GOx, Au@Ag heterogeneous NRs, and ABTS at nearly neutral pH (pH 6.5) and 37 °C. This proposed method had simple and rapid processes, wide linear range (0.05-20 mM), and reliability for the successful analysis of real samples. On the basis of these attractive and unique characteristics, Au@Ag heterogeneous NRs can become promising substitutes for peroxidase in analytical chemistry and environmental science. PMID:26076372

  6. Plasmon enhanced photoelectrochemical sensing of mercury (II) ions in human serum based on Au@Ag nanorods modified TiO2 nanosheets film.

    PubMed

    Zhang, Yong; Shoaib, Anwer; Li, Jiaojiao; Ji, Muwei; Liu, Jiajia; Xu, Meng; Tong, Bin; Zhang, Jiatao; Wei, Qin

    2016-05-15

    Taking advantages of the monodisperse TiO2 nanosheets (NSs) with high active crystal face exposure and the tunable localized surface plasmon resonance (LSPR) properties of Au@Ag nanorods (NRs), this study demonstrated that TiO2 NSs film with trace amount of Au@Ag NRs modification possess a strong enhancement of photocurrent response, which was remarkably inhibited with the addition of mercury (II) ions (Hg(2+)). Based on the selective decrease of photocurrent with the addition of Hg(2+), a simple photoelectrochemical (PEC) sensor has been assembled. The PEC sensor exhibits wide linear range (0.01-10nM), low detection limit (2.5pM), satisfying selectivity, reproducibility and acceptable stability for Hg(2+) detection. The feasibility of this method for practical application in human serum has been evaluated and the result was satisfactory. This PEC sensing method would provide a potential application for Hg(2+) detection in clinical diagnosis. PMID:26785311

  7. Synthesize and characterize of Ag3VO4/TiO2 nanorods photocatalysts and its photocatalytic activity under visible light irradiation

    NASA Astrophysics Data System (ADS)

    Zou, Xuejun; Dong, Yuying; Zhang, Xiaodong; Cui, Yubo

    2016-03-01

    In this paper, in order to expand the light response range of TiO2, Ag3VO4/TiO2 nanorods photocatalysts were fabricated by a simple sol-gel method with microwave and hydrothermal method. The as-prepared samples were characterized by XRD, SEM, DRS, XPS and N2 adsorption-desorption. Meanwhile, their photocatalytic properties were investigated by the degradation of toluene under visible light irradiation. The degradation conversation of toluene had gotten to about 70% in 1% Ag3VO4/TiO2 nanorods after reaction 4 h. The predominant photocatalytic activity can be attributed to its strong absorption in visible light region and excellent charge separation characteristics. By using in situ FTIR, benzyl alcohol and benzaldehyde species could be observed during the reaction and the formed intermediates would be partially oxidized into CO2 and H2O. Electron spin resonance confirmed that OHrad and O2rad - were involved in the photocatalytic degradation of toluene.

  8. Bio-mimetic Nanostructure Self-assembled from Au@Ag Heterogeneous Nanorods and Phage Fusion Proteins for Targeted Tumor Optical Detection and Photothermal Therapy

    PubMed Central

    Wang, Fei; Liu, Pei; Sun, Lin; Li, Cuncheng; Petrenko, Valery A.; Liu, Aihua

    2014-01-01

    Nanomaterials with near-infrared (NIR) absorption have been widely studied in cancer detection and photothermal therapy (PTT), while it remains a great challenge in targeting tumor efficiently with minimal side effects. Herein we report a novel multifunctional phage-mimetic nanostructure, which was prepared by layer-by-layer self-assembly of Au@Ag heterogenous nanorods (NRs) with rhodamine 6G, and specific pVIII fusion proteins. Au@Ag NRs, first being applied for PTT, exhibited excellent stability, cost-effectivity, biocompatibility and tunable NIR absorption. The fusion proteins were isolated from phage DDAGNRQP specifically selected from f8/8 landscape phage library against colorectal cancer cells in a high-throughput way. Considering the definite charge distribution and low molecular weight, phage fusion proteins were assembled on the negatively charged NR core by electrostatic interactions, exposing the N-terminus fused with DDAGNRQP peptide on the surface. The fluorescent images showed that assembled phage fusion proteins can direct the nanostructure into cancer cells. The nanostructure was more efficient than gold nanorods and silver nanotriangle-based photothermal agents and was capable of specifically ablating SW620 cells after 10 min illumination with an 808 nm laser in the light intensity of 4 W/cm2. The prepared nanostructure would become an ideal reagent for simutaneously targeted optical imaging and PTT of tumor. PMID:25348392

  9. In situ plasma sputtering synthesis of ZnO nanorods-Ag nanoparticles hybrids and their application in non-enzymatic hydrogen peroxide sensing.

    PubMed

    Zhang, Dan; Zhang, Yuxia; Yang, Chi; Ge, Cunwang; Wang, Yuanhong; Wang, Hao; Liu, Hongying

    2015-08-21

    In this paper, ZnO nanorods-Ag nanoparticles hybrids were first synthesized via a facile, rapid, and in situ plasma sputtering method without using any silver precursor. The obtained materials were then characterized by scanning electron microscopy, high-resolution transmission electron microscopy, energy-dispersive x-ray spectroscopy, and cyclic voltammetry. Based on the electrochemical catalytic properties of the obtained nanohybrids, a non-enzymatic hydrogen peroxide biosensor was constructed by immobilizing the obtained ZnO nanorods-Ag nanoparticles hybrids on the surface of a glassy carbon electrode. Under optimal conditions, the resulting biosensor displayed a good response for H2O2 with a linear range of 0.2 to 12.8 mM, and a detection limit of 7.8 μM at a signal-to-noise ratio of 3. In addition, it exhibited excellent anti-interference ability and fast response. The current work provides a feasible platform to fabricate a variety of non-enzymatic biosensors. PMID:26225726

  10. In situ plasma sputtering synthesis of ZnO nanorods-Ag nanoparticles hybrids and their application in non-enzymatic hydrogen peroxide sensing

    NASA Astrophysics Data System (ADS)

    Zhang, Dan; Zhang, Yuxia; Yang, Chi; Ge, Cunwang; Wang, Yuanhong; Wang, Hao; Liu, Hongying

    2015-08-01

    In this paper, ZnO nanorods-Ag nanoparticles hybrids were first synthesized via a facile, rapid, and in situ plasma sputtering method without using any silver precursor. The obtained materials were then characterized by scanning electron microscopy, high-resolution transmission electron microscopy, energy-dispersive x-ray spectroscopy, and cyclic voltammetry. Based on the electrochemical catalytic properties of the obtained nanohybrids, a non-enzymatic hydrogen peroxide biosensor was constructed by immobilizing the obtained ZnO nanorods-Ag nanoparticles hybrids on the surface of a glassy carbon electrode. Under optimal conditions, the resulting biosensor displayed a good response for H2O2 with a linear range of 0.2 to 12.8 mM, and a detection limit of 7.8 μM at a signal-to-noise ratio of 3. In addition, it exhibited excellent anti-interference ability and fast response. The current work provides a feasible platform to fabricate a variety of non-enzymatic biosensors.

  11. Bio-mimetic Nanostructure Self-assembled from Au@Ag Heterogeneous Nanorods and Phage Fusion Proteins for Targeted Tumor Optical Detection and Photothermal Therapy

    NASA Astrophysics Data System (ADS)

    Wang, Fei; Liu, Pei; Sun, Lin; Li, Cuncheng; Petrenko, Valery A.; Liu, Aihua

    2014-10-01

    Nanomaterials with near-infrared (NIR) absorption have been widely studied in cancer detection and photothermal therapy (PTT), while it remains a great challenge in targeting tumor efficiently with minimal side effects. Herein we report a novel multifunctional phage-mimetic nanostructure, which was prepared by layer-by-layer self-assembly of Au@Ag heterogenous nanorods (NRs) with rhodamine 6G, and specific pVIII fusion proteins. Au@Ag NRs, first being applied for PTT, exhibited excellent stability, cost-effectivity, biocompatibility and tunable NIR absorption. The fusion proteins were isolated from phage DDAGNRQP specifically selected from f8/8 landscape phage library against colorectal cancer cells in a high-throughput way. Considering the definite charge distribution and low molecular weight, phage fusion proteins were assembled on the negatively charged NR core by electrostatic interactions, exposing the N-terminus fused with DDAGNRQP peptide on the surface. The fluorescent images showed that assembled phage fusion proteins can direct the nanostructure into cancer cells. The nanostructure was more efficient than gold nanorods and silver nanotriangle-based photothermal agents and was capable of specifically ablating SW620 cells after 10 min illumination with an 808 nm laser in the light intensity of 4 W/cm2. The prepared nanostructure would become an ideal reagent for simutaneously targeted optical imaging and PTT of tumor.

  12. Ag-ZnO nanoreactor grown on FTO substrate exhibiting high heterogeneous photocatalytic efficiency.

    PubMed

    Tan, Sin Tee; Ali Umar, Akrajas; Balouch, Aamna; Nafisah, Suratun; Yahaya, Muhammad; Yap, Chi Chin; Mat Salleh, Muhamad; Kityk, I V; Oyama, Munetaka

    2014-07-14

    This Research Article reports an unusually high efficiency heterogeneous photodegradation of methyl orange (MO) in the presence of Ag nanoparticle-loaded ZnO quasi-nanotube or nanoreactor (A-ZNRs) nanocatalyst grown on FTO substrate. In typical process, photodegradation efficiency of as high as 21.6% per μg per Watts of used catalyst and UV power can be normally obtained within only a 60-min reaction time from this system, which is 10(3) order higher than the reported results. This is equivalent to the turnover frequency of 360 mol mol(-1) h(-1). High-density hexagonal A-ZNRs catalysts were grown directly on FTO substrate via a seed-mediated microwave-assisted hydrolysis growth process utilizing Ag nanoparticle of approximately 3 nm in size as nanoseed and mixture aqueous solution of Zn(NO3)·6H2O, hexamethylenetetramine (HMT), and AgNO3 as the growth solution. A-ZNRs adopts hexagonal cross-section morphology with the inner surface of the reactor characterized by a rough and rugged structure. Transmission electron microscopy imaging shows the Ag nanoparticle grows interstitially in the ZnO nanoreactor structure. The high photocatalytic property of the A-ZNRs is associated with the highly active of inner side's surface of A-ZNRs and the oxidizing effect of Ag nanoparticle. The growth mechanism as well as the mechanism of the enhanced-photocatalytic performance of the A-ZNRs will be discussed. PMID:24919039

  13. Plasmonic color analysis of Ag-coated black-Si SERS substrate.

    PubMed

    Asiala, Steven M; Marr, James M; Gervinskas, Gediminas; Juodkazis, Saulius; Schultz, Zachary D

    2015-11-11

    Red-Green-Blue (RGB) dark-field imaging can direct the choice of laser excitation for Raman enhancements on nanostructured plasmonic surfaces. Here we demonstrate that black silicon (b-Si) is a structured surface that has been shown to effectively absorb broad wavelengths of light, but also enables surface enhanced Raman scattering (SERS) when coated with silver (Ag). Coating b-Si with increasing amounts of Ag results in increased dark-field scattering at discrete frequencies associated with localized plasmon resonances. The dark-field scattering was monitored by collecting a far-field image with an inexpensive complementary metal oxide semiconductor (CMOS) camera, similar to what is available on most mobile phones. Color analysis of the RGB pixel intensities correlates with the observed SERS intensity obtained with either green (532 nm) or red (633 nm) laser excitation in SERS experiments. Of particular note, the SERS response at 633 nm showed low spectral variation and a lack of background scattering compared to SERS at 532 nm. The difference in background suggests sub-radiant (dark or Fano resonances) may be associated with the SERS response at 633 nm and a non-resonant character of SERS. These results indicate that b-Si serves a template where Ag nucleates during physical vapor deposition. Increased deposition causes the deposits to coalesce, and at larger Ag thicknesses, bulk scattering is observed. Comparison with a high enhancement Ag SERS substrate further illustrates that a high density of plasmonic junctions, or hotspots, is important for maximizing the SERS response. The randomness of the b-Si substrate and the corresponding Ag nano-features contributes to a broadband spectral response and enhancement in SERS. Metal-coated b-Si is a promising SERS substrate due to its performance and facile fabrication. PMID:26510016

  14. Tuning the SERS Response with Ag-Au Nanoparticle-Embedded Polymer Thin Film Substrates.

    PubMed

    Rao, V Kesava; Radhakrishnan, T P

    2015-06-17

    Development of facile routes to the fabrication of thin film substrates with tunable surface enhanced Raman scattering (SERS) efficiency and identification of the optimal conditions for maximizing the enhancement factor (EF) are significant in terms of both fundamental and application aspects of SERS. In the present work, polymer thin films with embedded bimetallic nanoparticles of Ag-Au are fabricated by a simple two-stage protocol. Ag nanoparticles are formed in the first stage, by the in situ reduction of silver nitrate by the poly(vinyl alcohol) (PVA) film through mild thermal annealing, without any additional reducing agent. In the second stage, aqueous solutions of chloroauric acid spread on the Ag-PVA thin film under ambient conditions, lead to the galvanic displacement of Ag by Au in situ inside the film, and the formation of Ag-Au particles. Evolution of the morphology of the bimetallic nanoparticles into hollow cage structures and the distribution of Au on the nanoparticles are revealed through electron microscopy and energy dispersive X-ray spectroscopy. The localized surface plasmon resonance (LSPR) extinction of the nanocomposite thin film evolves with the Ag-Au composition; theoretical simulation of the extinction spectra provides insight into the observed trends. The Ag-Au-PVA thin films are found to be efficient substrates for SERS. The EF follows the variation of the LSPR extinction vis-à-vis the excitation laser wavelength, but with an offset, and the maximum SERS effect is obtained at very low Au content; experiments with Rhodamine 6G showed EFs on the order of 10(8) and a limit of detection of 0.6 pmol. The present study describes a facile and simple fabrication of a nanocomposite thin film that can be conveniently deployed in SERS investigations, and the utility of the bimetallic system to tune and maximize the EF. PMID:26035249

  15. Direct deposition of YBCO on polished Ag substrates by pulsed laser deposition.

    SciTech Connect

    Ma, B.; Li, M.; Koritala, R. E.; Fisher, B. L.; Dorris, S. E.; Maroni, V. A.; Miller, D. J.; Balachandran, U.

    2002-09-15

    YBCO thin films were directly deposited on mechanically polished nontextured silver (Ag) substrates at elevated temperature by pulsed laser deposition with various inclination angles of 35, 55, and 72. Strong fiber texture, with the c-axis parallel to the substrate normal was detected by X-ray diffraction pole figure analysis. Atomic force microscopy and scanning electron microscopy images revealed that a few a-axis-oriented grains were dispersed on the top surface of the YBCO films. Transmission electron microscopy revealed dense amorphous layer at the interface between the YBCO film and the Ag substrate. Energy dispersive spectrum analysis indicates that the YBCO film deposited on the Ag substrate is slightly Cu-deficient. A YBCO film deposited at 755 C and an inclination angle of 55 exhibited {Tc} = 90 K. Transport critical current density measured by the four-probe method at 77 K in self-field was 2.7 x 10{sup 5}A/cm2. This work demonstrated a simple and inexpensive method to fabricate YBCO-coated conductors with high critical current density.

  16. Tribological properties of Ag/Ti films on Al2O3 ceramic substrates

    NASA Technical Reports Server (NTRS)

    Dellacorte, Christopher; Pepper, Stephen V.; Honecy, Frank S.

    1991-01-01

    Ag solid lubricant films, with a thin Ti interlayer for enhanced adhesion, were sputter deposited on Al2O3 substrate disks to reduce friction and wear. The dual Ag/Ti films were tested at room temperature in a pin-on-disk tribometer sliding against bare, uncoated Al2O3 pins under a 4.9 N load at a sliding velocity of 1 m/s. The Ag/Ti films reduced the friction coefficient by 50 percent to about 0.41 compared to unlubricated baseline specimens. Pin wear was reduced by a factor of 140 and disk wear was reduced by a factor of 2.5 compared to the baseline. These films retain their good tribological properties including adhesion after heat treatments at 850 C and thus may be able to lubricate over a wide temperature range. This lubrication technique is applicable to space lubrication, advanced heat engines, and advanced transportation systems.

  17. Quantification of proteins using enhanced etching of Ag coated Au nanorods by the Cu2+/bicinchoninic acid pair with improved sensitivity

    NASA Astrophysics Data System (ADS)

    Liu, Wenqi; Hou, Shuai; Yan, Jiao; Zhang, Hui; Ji, Yinglu; Wu, Xiaochun

    2015-12-01

    Plasmonic nanosensors show great potential in ultrasensitive detection, especially with the plasmon peak position as the detection modality. Herein, a new sensitive but simple total protein quantification method termed the SPR-BCA assay is demonstrated by combining plasmonic nanosensors with protein oxidation by Cu2+. The easy tuning of localized surface plasmon resonance (LSPR) features of plasmonic nanostructures makes them ideal sensing platforms. We found that the Cu2+/bicinchoninic acid (BCA) pair exhibits accelerated etching of Au@Ag nanorods and results in the LSPR peak shift. A linear relationship between Cu2+ and the LSPR shift is found in a double logarithmic coordinate. Such double logarithm relationship is transferred to the concentration of proteins. Theoretical simulation shows that Au nanorods with large aspect ratios and small core sizes show high detection sensitivity. Via optimized sensor design, we achieved an increased sensitivity (the limit of detection was 3.4 ng ml-1) and a wide working range (0.5 to 1000 μg ml-1) compared with the traditional BCA assay. The universal applicability of our method to various proteins further proves its potential in practical applications.Plasmonic nanosensors show great potential in ultrasensitive detection, especially with the plasmon peak position as the detection modality. Herein, a new sensitive but simple total protein quantification method termed the SPR-BCA assay is demonstrated by combining plasmonic nanosensors with protein oxidation by Cu2+. The easy tuning of localized surface plasmon resonance (LSPR) features of plasmonic nanostructures makes them ideal sensing platforms. We found that the Cu2+/bicinchoninic acid (BCA) pair exhibits accelerated etching of Au@Ag nanorods and results in the LSPR peak shift. A linear relationship between Cu2+ and the LSPR shift is found in a double logarithmic coordinate. Such double logarithm relationship is transferred to the concentration of proteins. Theoretical

  18. A chemically inert Rashba split interface electronic structure of C60, FeOEP and PTCDA on BiAg2/Ag(111) substrates

    NASA Astrophysics Data System (ADS)

    Cottin, Maren C.; Lobo-Checa, Jorge; Schaffert, Johannes; Bobisch, Christian A.; Möller, Rolf; Ortega, J. Enrique; Walter, Andrew L.

    2014-04-01

    The fields of organic electronics and spintronics have the potential to revolutionize the electronics industry. Finding the right materials that can retain their electrical and spin properties when combined is a technological and fundamental challenge. We carry out the study of three archetypal organic molecules in intimate contact with the BiAg2 surface alloy. We show that the BiAg2 alloy is an especially suited substrate due to its inertness as support for molecular films, exhibiting an almost complete absence of substrate-molecular interactions. This is inferred from the persistence of a completely unaltered giant spin-orbit split surface state of the BiAg2 substrate, and from the absence of significant metallic screening of charged molecular levels in the organic layer. Spin-orbit split states in BiAg2 turn out to be far more robust to organic overlayers than previously thought.

  19. Ag@Au core-shell dendrites: a stable, reusable and sensitive surface enhanced Raman scattering substrate

    NASA Astrophysics Data System (ADS)

    Jun Yin, Hong; Yang Chen, Zhao; Mei Zhao, Yong; Yang Lv, Ming; An Shi, Chun; Long Wu, Zheng; Zhang, Xin; Liu, Luo; Li Wang, Ming; Jun Xu, Hai

    2015-09-01

    Surface enhanced Raman scattering (SERS) substrate based on fabricated Ag@Au core-shell dendrite was achieved. Ag dendrites were grown on Si wafer by the hydrothermal corrosion method and Au nanofilm on the surface of Ag dendritic nanostructure was then fabricated by chemical reduction. With the help of sodium borohydride in water, Au surface absorbates such as thiophene, adenine, rhodamine, small anions (Br- and I-), and a polymer (PVP, poly(N-vinylpyrrolidone)) can be completely and rapidly removed. After four repeatable experiments, the substrate SERS function did not decrease at all, indicating that the Ag@Au dendrite should be of great significance to SERS application because it can save much resource. Six-month-duration stability tests showed that the Ag@Au core-shell dendrite substrate is much more stable than the Ag dendrite substrates. We have also experimented on fast detection of Cd2+ at 10-8  M concentration by decorating single-stranded DNA containing adenine and guanine bases on the surface of this Ag@Au dendrite. Finite-difference time-domain simulations were carried out to investigate the influence of Au nanolayer on Ag dendrites, which showed that the local electric fields and enhancement factor are hardly affected when a 4 nm Au nanolayer is coated on Ag dendrite surface.

  20. Ag@Au core-shell dendrites: a stable, reusable and sensitive surface enhanced Raman scattering substrate.

    PubMed

    Yin, Hong Jun; Chen, Zhao Yang; Zhao, Yong Mei; Lv, Ming Yang; Shi, Chun An; Wu, Zheng Long; Zhang, Xin; Liu, Luo; Wang, Ming Li; Xu, Hai Jun

    2015-01-01

    Surface enhanced Raman scattering (SERS) substrate based on fabricated Ag@Au core-shell dendrite was achieved. Ag dendrites were grown on Si wafer by the hydrothermal corrosion method and Au nanofilm on the surface of Ag dendritic nanostructure was then fabricated by chemical reduction. With the help of sodium borohydride in water, Au surface absorbates such as thiophene, adenine, rhodamine, small anions (Br(-) and I(-)), and a polymer (PVP, poly(N-vinylpyrrolidone)) can be completely and rapidly removed. After four repeatable experiments, the substrate SERS function did not decrease at all, indicating that the Ag@Au dendrite should be of great significance to SERS application because it can save much resource. Six-month-duration stability tests showed that the Ag@Au core-shell dendrite substrate is much more stable than the Ag dendrite substrates. We have also experimented on fast detection of Cd(2+) at 10(-8) M concentration by decorating single-stranded DNA containing adenine and guanine bases on the surface of this Ag@Au dendrite. Finite-difference time-domain simulations were carried out to investigate the influence of Au nanolayer on Ag dendrites, which showed that the local electric fields and enhancement factor are hardly affected when a 4 nm Au nanolayer is coated on Ag dendrite surface. PMID:26412773

  1. Ag@Au core-shell dendrites: a stable, reusable and sensitive surface enhanced Raman scattering substrate

    PubMed Central

    Jun Yin, Hong; Yang Chen, Zhao; Mei Zhao, Yong; Yang Lv, Ming; An Shi, Chun; Long Wu, Zheng; Zhang, Xin; Liu, Luo; Li Wang, Ming; Jun Xu, Hai

    2015-01-01

    Surface enhanced Raman scattering (SERS) substrate based on fabricated Ag@Au core-shell dendrite was achieved. Ag dendrites were grown on Si wafer by the hydrothermal corrosion method and Au nanofilm on the surface of Ag dendritic nanostructure was then fabricated by chemical reduction. With the help of sodium borohydride in water, Au surface absorbates such as thiophene, adenine, rhodamine, small anions (Br– and I–), and a polymer (PVP, poly(N-vinylpyrrolidone)) can be completely and rapidly removed. After four repeatable experiments, the substrate SERS function did not decrease at all, indicating that the Ag@Au dendrite should be of great significance to SERS application because it can save much resource. Six-month-duration stability tests showed that the Ag@Au core-shell dendrite substrate is much more stable than the Ag dendrite substrates. We have also experimented on fast detection of Cd2+ at 10−8  M concentration by decorating single-stranded DNA containing adenine and guanine bases on the surface of this Ag@Au dendrite. Finite-difference time-domain simulations were carried out to investigate the influence of Au nanolayer on Ag dendrites, which showed that the local electric fields and enhancement factor are hardly affected when a 4 nm Au nanolayer is coated on Ag dendrite surface. PMID:26412773

  2. Multiplexed detection of protein cancer markers on Au/Ag-barcoded nanorods using fluorescent-conjugated polymers.

    PubMed

    Zheng, Weiming; He, Lin

    2010-07-01

    Integration of fluorescent-conjugated polymers as detection moiety with metallic striped nanorods for multiplexed detection of clinically important cancer marker proteins in an immunoassay format was demonstrated in this report. Specifically, cationic conjugated polymers were introduced to protein complexes through electrostatic binding to negatively charged double-stranded DNA, which was tagged on detection antibodies prior to antigen recognition. The intense fluorescence emission of conjugated polymers resulted in highly sensitive detection of cancer marker proteins wherein an undiluted bovine serum sample as low as approximately 25 target molecules captured on each particle was detectable. Meanwhile, the use of polymer molecules as the detection probe did not obscure the optical pattern of underlying nanorods, i.e., the encoding capability of barcoded nanorods was preserved, which allowed simultaneous detection of three cancer marker proteins with good specificity. PMID:20496173

  3. Reliability Investigations on SnAg Bumps on Substrate Pads with Different Pad Finish

    SciTech Connect

    Bauer, R.; Ebersberger, B.; Kupfer, C.; Alexa, L.

    2006-02-07

    SnAg solder bump is one bump type which is used to replace eutectic SnPb bumps. In this work tests have been done to characterize the reliability properties of this bump type. Electromigration (EM) tests, which were accelerated by high current and high temperature and high temperature storage (HTS) tests were performed. It was found that the reliability properties are sensitive to the material combinations in the interconnect stack. The interconnect stack includes substrate pad, pad finish, bump, underbump metallization (UBM) and the chip pad. Therefore separate test groups for SnAg bumps on Cu substrate pads with organic solderability preservative (OSP) finish and the identical bumps on pads with Ni/Au finish were used. In this paper the reliability test results and the corresponding failure analysis are presented. Some explanations about the differences in formation of intermetallic compounds (IMCs) are given.

  4. Ag-modified silicon nanowires substrate for ultrasensitive surface-enhanced raman spectroscopy

    NASA Astrophysics Data System (ADS)

    Shao, Ming-Wang; Zhang, Ming-Liang; Wong, Ning-Bew; Ma, Dorothy Duo-duo; Wang, Hui; Chen, Weiwei; Lee, Shuit-Tong

    2008-12-01

    We report a unique substrate for surface-enhanced raman spectroscopy (SERS) based on silver nanoparticles-embedded silicon nanowires (SiNWs). The SiNWs were prepared by thermal evaporation of SiO powder via oxide-assisted growth, oxide removed with HF, and then used to reduce silver ions to form a highly decorated Ag-embedded surface. Such modified SiNWs substrates yielded ultrahigh SERS sensitivity, which could detect 25μl of 1×10-16M Rhodamine 6G, 1×10-16M crystal violet, and 1×10-14M nicotine in methanol solutions. An Ag-modified SiNW strand could also enable SERS detection of 25μl of 1×10-8mg/ml calf thymus DNA. The possible mechanisms for the ultrahigh SERS sensitivity were discussed.

  5. First-principles identifications of superstructures of germanene on Ag(111) surface and h-BN substrate.

    PubMed

    Li, Linyang; Zhao, Mingwen

    2013-10-21

    Using first-principle calculations, we show that germanene can attach on Ag(111) surface forming germanene/Ag superstructures via electrostatic interactions. In all the optimized superstructures, we found a kind of epitaxially grown germanene is similar to the isolated low-buckled germanene. The adsorption energy of germanene on Ag(111) surface is about -464 meV to -428 meV per Ge atom, close to that of silicene on Ag(111) surface. Germanene on Ag(111) is a continuous layer and the p-d hybridization between Ag and Ge is revealed. These indicate Ag(111) surface is a good substrate for stabilizing germanene. The band structures of germanene are submerged in electronic states of metallic Ag substrate. To preserve the excellent electronic structures of germanene, we also considered another substrate hexagonal boron nitride (h-BN). We show that germanene can stably attach on h-BN substrate via Van der Waals (vdW) interactions, forming germanene/BN Moiré superstructures. At equilibrium state, a small band gap of about 50 meV is opened up in the Dirac point of germanene, whose value is insensitive to the rotation angle and the sliding between the two lattices, but can be effectively tuned by changing the interlayer distance. In these superstructures, the high carrier mobility of germanene is well preserved. These imply that h-BN can act as an ideal substrate material for germanene to achieve specific applications in nanoscale electronic devices. PMID:23995323

  6. Flexible membranes of Ag-nanosheet-grafted polyamide-nanofibers as effective 3D SERS substrates

    NASA Astrophysics Data System (ADS)

    Qian, Yiwu; Meng, Guowen; Huang, Qing; Zhu, Chuhong; Huang, Zhulin; Sun, Kexi; Chen, Bin

    2014-04-01

    We report on a synthetic approach to produce self-supported flexible surface-enhanced Raman scattering (SERS) active membranes consisting of polyamide (PA) nanofibers grafted with vertical Ag-nanosheets, via a combinatorial process of electrospinning PA-nanofiber membranes, assembling Au-nanoparticles on the PA-nanofibers as seeds for subsequent growth of Ag-nanosheets, and electrodepositing Ag-nanosheets on the electrospun PA-nanofibers. As a high density of Ag-nanosheets are vertically grown around each PA-nanofiber in the three-dimensional (3D) networked PA-nanofiber membranes, homogeneous nano-scaled gaps between the neighboring Ag-nanosheets are formed, leading to a high density of 3D SERS ``hot spots'' within the Ag-nanosheet-grafted PA-nanofiber membranes. The Ag-nanosheet-grafted PA-nanofiber membranes demonstrate high SERS activity with excellent Raman signal reproducibility for rhodamine 6G over the whole membrane. For a SERS-based trial analysis of polychlorinated biphenyls (PCBs, a kind of global environmental hazard), the 3D SERS substrate membranes are modified with mono-6-β-cychlodextrin to effectively capture PCB molecules. As a result, not only a low concentration down to 10-6 M is reached, but also two congeners of PCBs in their mixed solution are identified, showing promising potential in SERS-based rapid detection of trace organic pollutants such as PCBs in the environment.We report on a synthetic approach to produce self-supported flexible surface-enhanced Raman scattering (SERS) active membranes consisting of polyamide (PA) nanofibers grafted with vertical Ag-nanosheets, via a combinatorial process of electrospinning PA-nanofiber membranes, assembling Au-nanoparticles on the PA-nanofibers as seeds for subsequent growth of Ag-nanosheets, and electrodepositing Ag-nanosheets on the electrospun PA-nanofibers. As a high density of Ag-nanosheets are vertically grown around each PA-nanofiber in the three-dimensional (3D) networked PA

  7. Mechanism of strong visible light photocatalysis by Ag2O-nanoparticle-decorated monoclinic TiO2(B) porous nanorods.

    PubMed

    Paul, Kamal Kumar; Ghosh, Ramesh; Giri, P K

    2016-08-01

    We report on the ultra-high rate of photodegradation of organic dyes under visible light illumination on Ag2O-nanoparticle-decorated (NP) porous pure B-phase TiO2 (TiO2(B)) nanorods (NRs) grown by a solvothermal route. The as-grown TiO2(B) NRs are found to be nanoporous in nature and the Ag2O NPs are uniformly decorated over its surface, since most of the pores work as nucleation sites for the growth of Ag2O NPs. The effective band gap of the TiO2(B)/Ag2O heterostructure (HS), with a weight ratio of 1:1, has been significantly reduced to 1.68 eV from the pure TiO2(B) band gap of 2.8 eV. Steady state and time-resolved photoluminescence (PL) studies show the reduced intensity of visible PL and slower recombination dynamics in the HS samples. The photocatalytic degradation efficiency of the TiO2(B)/Ag2O HS has been investigated using aqueous methyl orange and methylene blue as reference dyes under visible light (390-800 nm) irradiation. It is found that photodegradation by the TiO2(B)/Ag2O HS is about one order of magnitude higher than that of bare TiO2(B) NRs and Ag2O NPs. The optimized TiO2(B)/Ag2O HS exhibited the highest photocatalytic efficiency, with 88.2% degradation for 30 min irradiation. The corresponding first order degradation rate constant is 0.071 min(-1), which is four times higher than the reported values. Furthermore, cyclic stability studies show the high stability of the HS photocatalyst for up to four cycles of use. The major improvement in photocatalytic efficiency has been explained on the basis of enhanced visible light absorption and band-bending-induced efficient charge separation in the HS. Our results demonstrate the long-term stability and superiority of the TiO2(B)/Ag2O HS over the bare TiO2(B) NRs and other TiO2-based photocatalysts for its cutting edge application in hydrogen production and environmental cleaning driven by solar light photocatalysis. PMID:27333816

  8. Mechanism of strong visible light photocatalysis by Ag2O-nanoparticle-decorated monoclinic TiO2(B) porous nanorods

    NASA Astrophysics Data System (ADS)

    Paul, Kamal Kumar; Ghosh, Ramesh; Giri, P. K.

    2016-08-01

    We report on the ultra-high rate of photodegradation of organic dyes under visible light illumination on Ag2O-nanoparticle-decorated (NP) porous pure B-phase TiO2 (TiO2(B)) nanorods (NRs) grown by a solvothermal route. The as-grown TiO2(B) NRs are found to be nanoporous in nature and the Ag2O NPs are uniformly decorated over its surface, since most of the pores work as nucleation sites for the growth of Ag2O NPs. The effective band gap of the TiO2(B)/Ag2O heterostructure (HS), with a weight ratio of 1:1, has been significantly reduced to 1.68 eV from the pure TiO2(B) band gap of 2.8 eV. Steady state and time-resolved photoluminescence (PL) studies show the reduced intensity of visible PL and slower recombination dynamics in the HS samples. The photocatalytic degradation efficiency of the TiO2(B)/Ag2O HS has been investigated using aqueous methyl orange and methylene blue as reference dyes under visible light (390–800 nm) irradiation. It is found that photodegradation by the TiO2(B)/Ag2O HS is about one order of magnitude higher than that of bare TiO2(B) NRs and Ag2O NPs. The optimized TiO2(B)/Ag2O HS exhibited the highest photocatalytic efficiency, with 88.2% degradation for 30 min irradiation. The corresponding first order degradation rate constant is 0.071 min‑1, which is four times higher than the reported values. Furthermore, cyclic stability studies show the high stability of the HS photocatalyst for up to four cycles of use. The major improvement in photocatalytic efficiency has been explained on the basis of enhanced visible light absorption and band-bending-induced efficient charge separation in the HS. Our results demonstrate the long-term stability and superiority of the TiO2(B)/Ag2O HS over the bare TiO2(B) NRs and other TiO2-based photocatalysts for its cutting edge application in hydrogen production and environmental cleaning driven by solar light photocatalysis.

  9. Electromagnetic wave propagation along T and Y-splitters composed of silicon nanorods, gold slots, and silica substrate

    NASA Astrophysics Data System (ADS)

    Ahmadivand, Arash; Pala, Nezih; Golmohammadi, Saeed

    2015-05-01

    Silicon nanorods in arrays on a glass substrate that are situated through a gap between two gold slots have been utilized to design efficient long-range optical nanostructures as splitters to function at near infrared spectrum. Designing silicon arrays in T and Y-shape regimes, we examined the optical responses of the proposed devices during guiding of transverse and longitudinal electric modes (TE and LE-modes). Transmission loss factors, group velocity of guided waves, the ratio of transmitted power, and the decay length for both of the devices have been reported using numerical methods. We showed that the proposed structures have strong potentials to employ in designing photonic structures with lower ratio of energy extinction and low radiation losses. The overall length of the structures is 2.2 μm which verifies its compaction in comparison to analogous splitters that are designed based on DLSPPWs and nanoparticle-based waveguides devices. Proposed subwavelength optical power transportation mechanisms are highly compatible to employ in photonic integration circuit (PIC) systems.

  10. Structural and compositional evolutions of InxAl1-xN core-shell nanorods grown on Si(111) substrates by reactive magnetron sputter epitaxy.

    PubMed

    Serban, Elena Alexandra; Åke Persson, Per Ola; Poenaru, Iuliana; Junaid, Muhammad; Hultman, Lars; Birch, Jens; Hsiao, Ching-Lien

    2015-05-29

    Catalystless growth of InxAl(1-x)N core-shell nanorods have been realized by reactive magnetron sputter epitaxy onto Si(111) substrates. The samples were characterized by scanning electron microscopy, x-ray diffraction, scanning transmission electron microscopy, and energy dispersive x-ray spectroscopy. The composition and morphology of InxAl(1-x)N nanorods are found to be strongly influenced by the growth temperature. At lower temperatures, the grown materials form well-separated and uniform core-shell nanorods with high In-content cores, while a deposition at higher temperature leads to the formation of an Al-rich InxAl(1-x)N film with vertical domains of low In-content as a result of merging Al-rich shells. The thickness and In content of the cores (domains) increase with decreasing growth temperature. The growth of the InxAl(1-x)N is traced to the initial stage, showing that the formation of the core-shell nanostructures starts very close to the interface. Phase separation due to spinodal decomposition is suggested as the origin of the resultant structures. Moreover, the in-plane crystallographic relationship of the nanorods and substrate was modified from a fiber textured to an epitaxial growth with an epitaxial relationship of InxAl(1-x)N[0001]//Si[111] and InxAl(1-x)N[1120]//Si[110 by removing the native SiOx layer from the substrate. PMID:25944838

  11. Structural and compositional evolutions of InxAl1-xN core-shell nanorods grown on Si(111) substrates by reactive magnetron sputter epitaxy

    NASA Astrophysics Data System (ADS)

    Serban, Elena Alexandra; Åke Persson, Per Ola; Poenaru, Iuliana; Junaid, Muhammad; Hultman, Lars; Birch, Jens; Hsiao, Ching-Lien

    2015-05-01

    Catalystless growth of InxAl1-xN core-shell nanorods have been realized by reactive magnetron sputter epitaxy onto Si(111) substrates. The samples were characterized by scanning electron microscopy, x-ray diffraction, scanning transmission electron microscopy, and energy dispersive x-ray spectroscopy. The composition and morphology of InxAl1-xN nanorods are found to be strongly influenced by the growth temperature. At lower temperatures, the grown materials form well-separated and uniform core-shell nanorods with high In-content cores, while a deposition at higher temperature leads to the formation of an Al-rich InxAl1-xN film with vertical domains of low In-content as a result of merging Al-rich shells. The thickness and In content of the cores (domains) increase with decreasing growth temperature. The growth of the InxAl1-xN is traced to the initial stage, showing that the formation of the core-shell nanostructures starts very close to the interface. Phase separation due to spinodal decomposition is suggested as the origin of the resultant structures. Moreover, the in-plane crystallographic relationship of the nanorods and substrate was modified from a fiber textured to an epitaxial growth with an epitaxial relationship of InxAl1-xN[0001]//Si[111] and InxAl1-xN[11\\bar{2}0]//Si[1\\bar{1}0] by removing the native SiOx layer from the substrate.

  12. Quantification of proteins using enhanced etching of Ag coated Au nanorods by the Cu(2+)/bicinchoninic acid pair with improved sensitivity.

    PubMed

    Liu, Wenqi; Hou, Shuai; Yan, Jiao; Zhang, Hui; Ji, Yinglu; Wu, Xiaochun

    2016-01-14

    Plasmonic nanosensors show great potential in ultrasensitive detection, especially with the plasmon peak position as the detection modality. Herein, a new sensitive but simple total protein quantification method termed the SPR-BCA assay is demonstrated by combining plasmonic nanosensors with protein oxidation by Cu(2+). The easy tuning of localized surface plasmon resonance (LSPR) features of plasmonic nanostructures makes them ideal sensing platforms. We found that the Cu(2+)/bicinchoninic acid (BCA) pair exhibits accelerated etching of Au@Ag nanorods and results in the LSPR peak shift. A linear relationship between Cu(2+) and the LSPR shift is found in a double logarithmic coordinate. Such double logarithm relationship is transferred to the concentration of proteins. Theoretical simulation shows that Au nanorods with large aspect ratios and small core sizes show high detection sensitivity. Via optimized sensor design, we achieved an increased sensitivity (the limit of detection was 3.4 ng ml(-1)) and a wide working range (0.5 to 1000 μg ml(-1)) compared with the traditional BCA assay. The universal applicability of our method to various proteins further proves its potential in practical applications. PMID:26669539

  13. High-intensity laser for Ta and Ag implantation into different substrates for plasma diagnostics

    NASA Astrophysics Data System (ADS)

    Cutroneo, M.; Mackova, A.; Malinsky, P.; Matousek, J.; Torrisi, L.; Ullschmied, J.

    2015-07-01

    High-intensity lasers generating non-equilibrium plasma, can be employed to accelerate ions in the keV-MeV region, useful for many applications. In the present work, we performed study of ion implantation into different substrates by using a high-intensity laser at the PALS laboratory in Prague. Multi-energy ions generated by plasma from Ta and Ag targets were implanted into polyethylene and metallic substrates (Al, Ti) at energies of tens of keV per charge state. The ion emission was monitored online using time-of-flight detectors and electromagnetic deflection systems. Rutherford Backscattering Spectrometry (RBS) was used to characterise the elemental composition in the implanted substrates by ion plasma emission and to provide the implanted ion depth profiling. These last measurements enable offline plasma characterisation and provide information on the useful potentiality of multi-ion species and multi-energy ion implantation into different substrates. XPS analysis gives information on the chemical bonds and their modifications in the first superficial implanted layers. The depth distributions of implanted Ta and Ag ions were compared with the theoretical ones achieved by using the SRIM-2012 simulation code.

  14. SERS-active Ag Nanostars Substrates for Sensitive Detection of Ethyl Carbamate in Wine.

    PubMed

    Li, Manli; Zhao, Yuan; Cui, Malin; Wang, Chan; Song, Qijun

    2016-01-01

    A simple and sensitive surface-enhanced Raman scattering (SERS) method for the detection of ethyl carbamate (EC) is reported in this work. Star-shaped silver nanostars (Ag NSs) were used as a novel SERS substrate. In comparison to other plasmonic nanoparticles (NPs), including Au NPs, Au NSs and Ag NPs, Ag NSs exhibit best SERS activity. Raman signal of EC at a trace level can be enhanced by several orders of magnitude with the help of Ag NSs. The Raman intensity of EC increased linearly with an increase of the EC concentration in the range from 5 × 10(-9) mol L(-1) to 1.0 × 10(-4) mol L(-1) with detection limit (LOD) of 1.37 × 10(-9) mol L(-1) (S/N = 3). The developed SERS approach also has the advantages of being simple, fast and requiring less amount of the sample. It could serve as a useful technology for the rapid determination of EC in both alcoholic beverages and fermented food. PMID:27396651

  15. An ultrasensitive, uniform and large-area surface-enhanced Raman scattering substrate based on Ag or Ag/Au nanoparticles decorated Si nanocone arrays

    NASA Astrophysics Data System (ADS)

    Zhang, P. P.; Gao, J.; Sun, X. H.

    2015-01-01

    Large-area and highly ordered Si nanocone arrays decorated with Ag or Au/Ag nanoparticles have been fabricated via a mask-free lithography with reaction ion etching, followed by metal deposition process. Ultrasensitive surface enhanced Raman scattering signals with an enhancement factor of 1012 were achieved even at the concentration of the Rhodamine 6G as low as 10-15 M. The surface-enhanced Raman spectroscopy (SERS) substrate was also applied on the detection of Sudan I dye and the Raman signals were substantially enhanced as well. The stability of the SERS substrate can be significantly improved by covering Ag nanoparticles with Au thin layer, which maintain a high SERS performance even after one month storage. This nanofabrication process appears to be a feasible approach to prepare uniform and reproducible SERS-active substrates with high sensitivity and stability for practical SERS applications.

  16. Well aligned ZnO nanorods growth on the gold coated glass substrate by aqueous chemical growth method using seed layer of Fe3O4 and Co3O4 nanoparticles

    NASA Astrophysics Data System (ADS)

    Ibupoto, Z. H.; Khun, K.; Lu, Jun; Liu, Xianjie; AlSalhi, M. S.; Atif, M.; Ansari, Anees A.; Willander, M.

    2013-04-01

    In this study, Fe3O4 and Co3O4 nanoparticles were prepared by co-precipitation method and sol-gel method respectively. The synthesised nanoparticles were characterised by X-ray diffraction [XRD] and Raman spectroscopy techniques. The obtained results have shown the nanocrystalline phase of obtained Fe3O4 and Co3O4 nanoparticles. Furthermore, the Fe3O4 and Co3O4 nanoparticles were used as seed layer for the fabrication of well-aligned ZnO nanorods on the gold coated glass substrate by aqueous chemical growth method. Scanning electron microscopy (SEM), high resolution transmission electron microscopy [HRTEM], as well as XRD and energy dispersive X-ray techniques were used for the structural characterisation of synthesised ZnO nanorods. This study has explored highly dense, uniform, well-aligned growth pattern along 0001 direction and good crystal quality of the prepared ZnO nanorods. ZnO nanorods are only composed of Zn and O atoms. Moreover, X-ray photoelectron spectroscopy was used for the chemical analysis of fabricated ZnO nanorods. In addition, the structural characterisation and the chemical composition study and the optical investigation were carried out for the fabricated ZnO nanorods and the photoluminescence [PL] spectrum have shown strong ultraviolet (UV) peak at 381 nm for Fe3O4 nanoparticles seeded ZnO nanorods and the PL spectrum for ZnO nanorods grown with the seed layer of Co3O4 nanoparticles has shown a UV peak at 382 nm. The green emission and orange/red peaks were also observed for ZnO nanorods grown with both the seed layers. This study has indicated the fabrication of well aligned ZnO nanorods using the one inorganic nanomaterial on other inorganic nanomaterial due to their similar chemistry.

  17. Formation of oxides and their role in the growth of Ag nanoplates on GaAs substrates.

    SciTech Connect

    Sun, Y.; Gosztola, D.; Lei, C.; Haasch, R.; Center for Nanoscale Materials; Univ. of Illinois

    2008-10-21

    Simple galvanic reactions between highly doped n-type GaAs wafers and a pure aqueous solution of AgNO3 at room temperature provide an easy and efficient protocol to directly deposit uniform Ag nanoplates with tunable dimensions on the GaAs substrates. The anisotropic growth of the Ag nanoplates in the absence of surfactant molecules might be partially ascribed to the codeposition of oxides of gallium and arsenic, which are revealed by extensive data from electron microscopy, X-ray photoelectron spectroscopy, and Raman spectroscopy, during the growth of the Ag nanoplates. The electron microscopic characterization shows that each Ag nanoplate has a 'necked' geometry, that is, it pins on the GaAs lattices through only a tiny neck (with sizes of <10 nm). In addition, the as-grown Ag nanoplates exhibit strong enhancement toward Raman scattering of materials on (or around) their surfaces.

  18. Hierarchically plasmonic photocatalysts of Ag/AgCl nanocrystals coupled with single-crystalline WO3 nanoplates

    NASA Astrophysics Data System (ADS)

    Chen, Deliang; Li, Tao; Chen, Qianqian; Gao, Jiabing; Fan, Bingbing; Li, Jian; Li, Xinjian; Zhang, Rui; Sun, Jing; Gao, Lian

    2012-08-01

    The hierarchical photocatalysts of Ag/AgCl@plate-WO3 have been synthesized by anchoring Ag/AgCl nanocrystals on the surfaces of single-crystalline WO3 nanoplates that were obtained via an intercalation and topochemical approach. The heterogeneous precipitation process of the PVP-Ag+-WO3 suspensions with a Cl- solution added drop-wise was developed to synthesize AgCl@WO3 composites, which were then photoreduced to form Ag/AgCl@WO3 nanostructures in situ. WO3 nanocrystals with various shapes (i.e., nanoplates, nanorods, and nanoparticles) were used as the substrates to synthesize Ag/AgCl@WO3 photocatalysts, and the effects of the WO3 contents and photoreduction times on their visible-light-driven photocatalytic performance were investigated. The techniques of TEM, SEM, XPS, EDS, XRD, N2 adsorption-desorption and UV-vis DR spectra were used to characterize the compositions, phases and microstructures of the samples. The RhB aqueous solutions were used as the model system to estimate the photocatalytic performance of the as-obtained Ag/AgCl@WO3 nanostructures under visible light (λ >= 420 nm) and sunlight. The results indicated that the hierarchical Ag/AgCl@plate-WO3 photocatalyst has a higher photodegradation rate than Ag/AgCl, AgCl, AgCl@WO3 and TiO2 (P25). The contents and morphologies of the WO3 substrates in the Ag/AgCl@plate-WO3 photocatalysts have important effects on their photocatalytic performance. The related mechanisms for the enhancement in visible-light-driven photodegradation of RhB molecules were analyzed.The hierarchical photocatalysts of Ag/AgCl@plate-WO3 have been synthesized by anchoring Ag/AgCl nanocrystals on the surfaces of single-crystalline WO3 nanoplates that were obtained via an intercalation and topochemical approach. The heterogeneous precipitation process of the PVP-Ag+-WO3 suspensions with a Cl- solution added drop-wise was developed to synthesize AgCl@WO3 composites, which were then photoreduced to form Ag/AgCl@WO3 nanostructures in

  19. Synthesis and characterization of Ag@Cu nano/microstructure ordered arrays as SERS-active substrates

    NASA Astrophysics Data System (ADS)

    Zhang, Pinhua; Cui, Guangliang; Xiao, Chuanhai; Zhang, Mingzhe; Chen, Li; Shi, Changmin

    2016-06-01

    We fabricated an Ag decorated Cu (Ag@Cu) nano/microstructure ordered array by facile template-free 2D electrodeposition combined with a galvanic reduction method for SERS applications. The Cu nano/microstructure ordered arrays were first synthesized by a 2D electrodeposition method, then Ag nanocubes were decorated on the arrays by galvanic reduction without any capping agent. The pollution-free surface and edge-to-face heterostructure of Ag nanocubes and Cu nano/microstructure arrays provide the powerful field-enhancements for SERS performance. The results verified that the Ag@Cu nano/microstructure ordered arrays have excellent activity for 4-Mercaptopyridine, and the sensitivity limit is as low as 10‑8 M. Therefore, this facile route provides a useful platform for the fabrication of a SERS substrate based on nano/microstructure ordered arrays.

  20. Ag-NP@Ge-nanotaper/Si-micropillar ordered arrays as ultrasensitive and uniform surface enhanced Raman scattering substrates

    NASA Astrophysics Data System (ADS)

    Liu, Jing; Meng, Guowen; Li, Zhongbo; Huang, Zhulin; Li, Xiangdong

    2015-10-01

    Surface-enhanced Raman scattering (SERS) is considered to be an excellent candidate for analytical detection schemes, because of its molecular specificity, rapid response and high sensitivity. Here, SERS-substrates of Ag-nanoparticle (Ag-NP) decorated Ge-nanotapers grafted on hexagonally ordered Si-micropillar (denoted as Ag-NP@Ge-nanotaper/Si-micropillar) arrays are fabricated via a combinatorial process of two-step etching to achieve hexagonal Si-micropillar arrays, chemical vapor deposition of flocky Ge-nanotapers on each Si-micropillar and decoration of Ag-NPs onto the Ge-nanotapers through galvanic displacement. With high density three-dimensional (3D) ``hot spots'' created from the large quantities of the neighboring Ag-NPs and large-scale uniform morphology, the hierarchical Ag-NP@Ge-nanotaper/Si-micropillar arrays exhibit strong and reproducible SERS activity. Using our hierarchical 3D SERS-substrates, both methyl parathion (a commonly used pesticide) and PCB-2 (one congener of highly toxic polychlorinated biphenyls) with concentrations down to 10-7 M and 10-5 M have been detected respectively, showing great potential in SERS-based rapid trace-level detection of toxic organic pollutants in the environment.Surface-enhanced Raman scattering (SERS) is considered to be an excellent candidate for analytical detection schemes, because of its molecular specificity, rapid response and high sensitivity. Here, SERS-substrates of Ag-nanoparticle (Ag-NP) decorated Ge-nanotapers grafted on hexagonally ordered Si-micropillar (denoted as Ag-NP@Ge-nanotaper/Si-micropillar) arrays are fabricated via a combinatorial process of two-step etching to achieve hexagonal Si-micropillar arrays, chemical vapor deposition of flocky Ge-nanotapers on each Si-micropillar and decoration of Ag-NPs onto the Ge-nanotapers through galvanic displacement. With high density three-dimensional (3D) ``hot spots'' created from the large quantities of the neighboring Ag-NPs and large-scale uniform

  1. Silver photo-diffusion and photo-induced macroscopic surface deformation of Ge33S67/Ag/Si substrate

    NASA Astrophysics Data System (ADS)

    Sakaguchi, Y.; Asaoka, H.; Uozumi, Y.; Kondo, K.; Yamazaki, D.; Soyama, K.; Ailavajhala, M.; Mitkova, M.

    2016-08-01

    Ge-chalcogenide films show various photo-induced changes, and silver photo-diffusion is one of them which attracts lots of interest. In this paper, we report how silver and Ge-chalcogenide layers in Ge33S67/Ag/Si substrate stacks change under light exposure in the depth by measuring time-resolved neutron reflectivity. It was found from the measurement that Ag ions diffuse all over the matrix Ge33S67 layer once Ag dissolves into the layer. We also found that the surface was macroscopically deformed by the extended light exposure. Its structural origin was investigated by a scanning electron microscopy.

  2. Controllable electrochemical synthesis of ZnO nanorod arrays on flexible ITO/PET substrate and their structural and optical properties

    NASA Astrophysics Data System (ADS)

    Ko, Yeong Hwan; Kim, Myung Sub; Yu, Jae Su

    2012-10-01

    The structural and optical properties of vertically aligned zinc oxide (ZnO) nanorod arrays (NRAs) which were grown on the flexible indium tin oxide (ITO) coated polyethylene terephthalate (PET) substrate (i.e., ITO/PET substrate) with a thin sputtered ZnO seed layer via the electrochemical deposition method were studied. By changing the applied voltage and zinc nitrate concentration, the height/width and density of ZnO NRAs were controlled, with investigation on their crystallinity and optical properties. To understand the effect of ZnO seed layer on the growth property of ZnO nanorods, they were also grown on ITO/PET without any seed layer. Under an applied cathodic voltage of -2 V and zinc nitrate concentration of 10 mM, the ZnO NRAs increased the total transmittance up to 88.7% in the visible wavelength region due to the antireflective property and their X-ray diffraction (0 0 2) peak intensity was largely enhanced. Additionally, the near band edge emission of ZnO was significantly enhanced in photoluminescence spectrum. The light scattering and surface wetting properties were also explored.

  3. Ligand-induced substrate steering and reshaping of [Ag2(H)](+) scaffold for selective CO2 extrusion from formic acid.

    PubMed

    Zavras, Athanasios; Khairallah, George N; Krstić, Marjan; Girod, Marion; Daly, Steven; Antoine, Rodolphe; Maitre, Philippe; Mulder, Roger J; Alexander, Stefanie-Ann; Bonačić-Koutecký, Vlasta; Dugourd, Philippe; O'Hair, Richard A J

    2016-01-01

    Metalloenzymes preorganize the reaction environment to steer substrate(s) along the required reaction coordinate. Here, we show that phosphine ligands selectively facilitate protonation of binuclear silver hydride cations, [LAg2(H)](+) by optimizing the geometry of the active site. This is a key step in the selective, catalysed extrusion of carbon dioxide from formic acid, HO2CH, with important applications (for example, hydrogen storage). Gas-phase ion-molecule reactions, collision-induced dissociation (CID), infrared and ultraviolet action spectroscopy and computational chemistry link structure to reactivity and mechanism. [Ag2(H)](+) and [Ph3PAg2(H)](+) react with formic acid yielding Lewis adducts, while [(Ph3P)2Ag2(H)](+) is unreactive. Using bis(diphenylphosphino)methane (dppm) reshapes the geometry of the binuclear Ag2(H)(+) scaffold, triggering reactivity towards formic acid, to produce [dppmAg2(O2CH)](+) and H2. Decarboxylation of [dppmAg2(O2CH)](+) via CID regenerates [dppmAg2(H)](+). These gas-phase insights inspired variable temperature NMR studies that show CO2 and H2 production at 70 °C from solutions containing dppm, AgBF4, NaO2CH and HO2CH. PMID:27265868

  4. Ligand-induced substrate steering and reshaping of [Ag2(H)]+ scaffold for selective CO2 extrusion from formic acid

    PubMed Central

    Zavras, Athanasios; Khairallah, George N.; Krstić, Marjan; Girod, Marion; Daly, Steven; Antoine, Rodolphe; Maitre, Philippe; Mulder, Roger J.; Alexander, Stefanie-Ann; Bonačić-Koutecký, Vlasta; Dugourd, Philippe; O'Hair, Richard A. J.

    2016-01-01

    Metalloenzymes preorganize the reaction environment to steer substrate(s) along the required reaction coordinate. Here, we show that phosphine ligands selectively facilitate protonation of binuclear silver hydride cations, [LAg2(H)]+ by optimizing the geometry of the active site. This is a key step in the selective, catalysed extrusion of carbon dioxide from formic acid, HO2CH, with important applications (for example, hydrogen storage). Gas-phase ion-molecule reactions, collision-induced dissociation (CID), infrared and ultraviolet action spectroscopy and computational chemistry link structure to reactivity and mechanism. [Ag2(H)]+ and [Ph3PAg2(H)]+ react with formic acid yielding Lewis adducts, while [(Ph3P)2Ag2(H)]+ is unreactive. Using bis(diphenylphosphino)methane (dppm) reshapes the geometry of the binuclear Ag2(H)+ scaffold, triggering reactivity towards formic acid, to produce [dppmAg2(O2CH)]+ and H2. Decarboxylation of [dppmAg2(O2CH)]+ via CID regenerates [dppmAg2(H)]+. These gas-phase insights inspired variable temperature NMR studies that show CO2 and H2 production at 70 °C from solutions containing dppm, AgBF4, NaO2CH and HO2CH. PMID:27265868

  5. Epitaxial growth of lead zirconium titanate thin films on Ag buffered Si substrates using rf sputtering

    SciTech Connect

    Wang Chun; Laughlin, David E.; Kryder, Mark H.

    2007-04-23

    Epitaxial lead zirconium titanate (PZT) (001) thin films with a Pt bottom electrode were deposited by rf sputtering onto Si(001) single crystal substrates with a Ag buffer layer. Both PZT(20/80) and PZT(53/47) samples were shown to consist of a single perovskite phase and to have the (001) orientation. The orientation relationship was determined to be PZT(001)[110](parallel sign)Pt(001)[110](parallel sign)Ag(001)[110](parallel sign)Si(001)[110]. The microstructure of the multilayer was studied using transmission electron microscopy (TEM). The electron diffraction pattern confirmed the epitaxial relationship between each layer. The measured remanent polarization P{sub r} and coercive field E{sub c} of the PZT(20/80) thin film were 26 {mu}C/cm{sup 2} and 110 kV/cm, respectively. For PZT(53/47), P{sub r} was 10 {mu}C/cm{sup 2} and E{sub c} was 80 kV/cm.

  6. Interfacial Microstructure Evolution Between Sn-Zn Solders and Ag Substrate During Solid-State Annealing

    NASA Astrophysics Data System (ADS)

    Wang, Chao-hong; Li, Po-yi; Li, Kuan-ting

    2014-12-01

    In this study, solid-state interfacial reactions between Ag and Sn-Zn alloys with varying Zn content (0.1 wt.% to 9 wt.%) were investigated at 170°C. The reaction couples were prepared by electroplating Ag on the Sn-Zn alloy to avoid dissolution of Ag into the molten solder during soldering. The Zn content greatly influenced the reaction products and the interfacial microstructures. When the Zn content was less than 4 wt.%, Ag3Sn and AgZn layers were simultaneously formed. Notably, Zn could actively diffuse through the Ag3Sn layer and react with Ag to form the AgZn phase. With the proceeding reaction, small α-Ag particulates were produced within the AgZn phase. With 9 wt.% Zn, the dominant reactions formed Ag5Zn8 and AgZn layers. The interfacial microstructure evolved significantly with reaction time. Interface instability due to Zn depletion in the solder resulted in massive spalling of the Ag5Zn8 layer. The Ag3Sn phase was then produced next to the AgZn layer. Moreover, another reaction couple, Sn-9 wt.%Zn/Sn(15 μm)/Ag, was prepared, in which fast interdiffusion between Zn and Ag across the Sn layer was demonstrated due to the strong chemical affinity of Zn.

  7. Ag Nanoparticles Decorated Cactus-Like Ag Dendrites/Si Nanoneedles as Highly Efficient 3D Surface-Enhanced Raman Scattering Substrates toward Sensitive Sensing.

    PubMed

    Huang, Jian; Ma, Dayan; Chen, Feng; Bai, Min; Xu, Kewei; Zhao, Yongxi

    2015-10-20

    Surface-enhanced Raman scattering (SERS) has been considered as a promising sensing technique to detect low-level analytes. However, its practical application was hindered owing to the lack of uniform SERS substrates for ultrasensitive and reproducible assay. Herein, inspired by the natural cactus structure, we developed a cactus-like 3D nanostructure with uniform and high-density hotspots for highly efficient SERS sensing by both grafting the silicon nanoneedles onto Ag dendrites and subsequent decoration with Ag nanoparticles. The hierarchical scaffolds and high-density hotspots throughout the whole substrate result in great amplification of SERS signal. A high Raman enhancement factor of crystal violet up to 6.6 × 10(7) was achieved. Using malachite green (MG) as a model target, the fabricated SERS substrates exhibited good reproducibility (RSD ∼ 9.3%) and pushed the detection limit down to 10(-13) M with a wide linear range of 10(-12) M to 10(-7) M. Excellent selectivity was also demonstrated by facilely distinguishing MG from its derivative, some organics, and coexistent metal ions. Finally, the practicality and reliability of the 3D SERS substrates were confirmed by the quantitative analysis of spiked MG in environmental water with high recoveries (91.2% to 109.6%). By virtue of the excellent performance (good reproducibility, high sensitivity, and selectivity), the cactus-like 3D SERS substrate has great potential to become a versatile sensing platform in environmental monitoring, food safety, and medical diagnostics. PMID:26406111

  8. Facile fabrication of Ag dendrite-integrated anodic aluminum oxide membrane as effective three-dimensional SERS substrate

    NASA Astrophysics Data System (ADS)

    Zhang, Cong-yun; Lu, Ya; Zhao, Bin; Hao, Yao-wu; Liu, Ya-qing

    2016-07-01

    A novel surface enhanced Raman scattering (SERS)-active substrate has been successfully developed, where Ag-dendrites are assembled on the surface and embedded in the channels of anodic aluminum oxide (AAO) membrane, via electrodeposition in AgNO3/PVP aqueous system. Reaction conditions were systematically investigated to attain the best Raman enhancement. The growth mechanism of Ag dendritic nanostructures has been proposed. The Ag dendrite-integrated AAO membrane with unique hierarchical structures exhibits high SERS activity for detecting rhodamine 6G with a detection limit as low as 1 × 10-11 M. Furthermore, the three-dimensional (3D) substrates display a good reproducibility with the average intensity variations at the major Raman peak less than 12%. Most importantly, the 3D SERS substrates without any surface modification show an outstanding SERS response for the molecules with weak affinity for noble metal surfaces. The potential application for the detection of polycyclic aromatic hydrocarbons (PAHs) was evaluated with fluoranthene as Raman target molecule and a sensitive SERS detection with a limit down to 10-8 M was reached. The 3D SERS-active substrate shows promising potential for rapid detection of trace organic pollutants even weak affinity molecules in the environment.

  9. Ag-nanoparticle-decorated porous ZnO-nanosheets grafted on a carbon fiber cloth as effective SERS substrates.

    PubMed

    Wang, Zhiwei; Meng, Guowen; Huang, Zhulin; Li, Zhongbo; Zhou, Qitao

    2014-12-21

    We report on the large-scale synthesis of Ag-nanoparticle (Ag-NP) decorated ZnO-mesoporous-nanosheets (NSs) grafted on a flexible carbon fiber cloth (CFC), as sensitive and reproducible surface enhanced Raman scattering (SERS) substrates with excellent flexibility. The composite SERS-substrates are achieved by a combination of atomic layer deposition of ZnO-seeds on each fiber of the CFC (denoted as ZnO-seeds@CFC), chemical bath deposition and subsequent pyrolysis for the creation of ZnO-mesoporous-NSs grafted on ZnO-seeds@CFC, and ion-sputtering of Ag-NPs on the ZnO-mesoporous-NSs. As abundant SERS "hot spots" are generated from the electromagnetic coupling of the densely distributed Ag-NPs, and the semiconducting ZnO-mesoporous-NSs also have chemical supporting enhancement and distinct molecule adsorbing abilities, the composite SERS-substrates demonstrate high SERS-sensitivity with good signal reproducibility. As a trial for potential applications, the composite SERS-substrates were used to identify pesticides and highly toxic polychlorinated biphenyls (PCBs), and low concentrations down to 10(-7) M for methyl parathion and 5 × 10(-6) M for PCB-77 were reached, respectively, showing promising potential for the SERS-based rapid detection of toxic organic pollutants in the environment. PMID:25382607

  10. Preparation of thin hexagonal highly-ordered anodic aluminum oxide (AAO) template onto silicon substrate and growth ZnO nanorod arrays by electrodeposition

    NASA Astrophysics Data System (ADS)

    Chahrour, Khaled M.; Ahmed, Naser M.; Hashim, M. R.; Elfadill, Nezar G.; Qaeed, M. A.; Bououdina, M.

    2014-12-01

    In this study, anodic aluminum oxide (AAO) templates of Aluminum thin films onto Ti-coated silicon substrates were prepared for growth of nanostructure materials. Hexagonally highly ordered thin AAO templates were fabricated under controllable conditions by using a two-step anodization. The obtained thin AAO templates were approximately 70 nm in pore diameter and 250 nm in length with 110 nm interpore distances within an area of 3 cm2. The difference between first and second anodization was investigated in details by in situ monitoring of current-time curve. A bottom barrier layer of the AAO templates was removed during dropping the voltage in the last period of the anodization process followed by a wet etching using phosphoric acid (5 wt%) for several minutes at ambient temperature. As an application, Zn nanorod arrays embedded in anodic alumina (AAO) template were fabricated by electrodeposition. Oxygen was used to oxidize the electrodeposited Zn nanorods in the AAO template at 700 °C. The morphology, structure and photoluminescence properties of ZnO/AAO assembly were analyzed using Field-emission scanning electron microscope (FESEM), Energy dispersive X-ray spectroscopy (EDX), Atomic force microscope (AFM), X-ray diffraction (XRD) and photoluminescence (PL).

  11. FO-SPR based dextrose sensor using Ag/ZnO nanorods/GOx for insulinoma detection.

    PubMed

    Usha, Sruthi P; Shrivastav, Anand M; Gupta, Banshi D

    2016-11-15

    In this piece of work, a fiber optic sensor has been fabricated and characterized using surface plasmon resonance for dextrose sensing. The concentration range used in this study is for diagnosing the cases of hypoglycaemia especially in suppression tests of insulinoma. Insulinoma is a medical case in which the person is recognized being hypoglycaemic with the blood dextrose level falling down to 2.2mM or less. Thus, the sensor has been characterized for the dextrose concentration range of 0 mM-10mM including the cases of normal blood dextrose range. Coatings of silver layer and zinc oxide nanorods have been carried out on the bare core fiber with a dual role of zinc oxide followed by immobilization of glucose oxidase. A three stage optimization procedure has been adopted for the best performance of the sensor. Absorbance spectra have been plotted and peak absorbance wavelengths have been extracted for each concentration chosen along with the sensitivities. The results have been made conclusive with control experiments. The probe has also been tested on sample having blood serum to check the reliability of the sensor. The sensor shows better selectivity and response time along with its real time applications, online monitoring, remote sensing and reusability. PMID:27268014

  12. Zinc oxide nanorods

    NASA Astrophysics Data System (ADS)

    Chik, Hope Wuming

    Non-lithographic, bottom-up techniques have been developed to advance the state of the art and contribute to the development of new material structures, fabrication methods, devices, and applications using the Zinc Oxide material system as a demonstration vehicle. The novel low temperature catalytic vapour-liquid-solid growth process developed is technologically simple, inexpensive, and a robust fabrication technique offering complete control over the physical dimensions of the nanorod such as its diameter and length, and over the positioning of the nanorods for site-selective growth. By controlling the distribution of the Au catalysts with the use of a self-organized anodized aluminum oxide nanopore membrane as a template, we have been able to synthesize highly ordered, hexagonally packed, array of ZnO nanorods spanning a large area. These nanorods are single crystal, hexagonally shaped, indicative of the wurtzite structure, and are vertically aligned to the substrate. By pre-patterning the template, arbitrary nanorod patterns can be formed. We have also demonstrated the assembly of the nanorods into functional devices using controlled methods that are less resource intensive, easily scalable, and adaptable to other material systems, without resorting to the manipulation of each individual nanostructures. Examples of these devices include the random network device that exploits the common attributes of the nanorods, and those formed using an external field to control the nanorod orientation. Two and three terminal device measurements show that the as-grown nanorods are n-type doped, and that by controlling the external optical excitation and its test environment, the photoconductivity can be altered dramatically. Self assemble techniques such as the spontaneous formation of nanodendrites into complex networks of interconnects were studied. Controlled formation of interconnects achieved by controlling the placement of the catalyst is demonstrated by growing the

  13. Arrays of ZnO nanorods decorated with Au nanoparticles as surface-enhanced Raman scattering substrates for rapid detection of trace melamine

    NASA Astrophysics Data System (ADS)

    Yi, Zao; Yi, Yong; Luo, Jiangshan; Li, Xibo; Xu, Xibin; Jiang, Xiaodong; Yi, Yougen; Tang, Yongjian

    2014-10-01

    In this paper, as a new, highly sensitive and uniform hybrid surface-enhanced Raman scattering (SERS) substrate, arrays of ZnO nanorods (ZnO-NRs) decorated with Au nanoparticles (Au-NPs) have been prepared. This hybrid substrate manifests high SERS sensitivity to melamine and a detection limit as low as 1.0×10-10 M (1.26 μg L-1). A maximum enhancement factor of 1.0×109 can be obtained with the ZnO NF-Au (sample 2) film. Au-NPs gaps in the array can create lots of SERS “hot spots” that mainly contribute to the high SERS sensitivity. Moreover, the supporting chemical enhancement effect of ZnO-NRs and the better enrichment effect ascribed to the large surface area of the substrate also help to achieve a lower detection limit. The promising advantages of easy sample pretreatment, short detection time and low cost makes the arrays of ZnO-NRs decorated with Au-NPs substrate a potential detection tool in the field of food safety.

  14. Size effect model on kinetics of interfacial reaction between Sn-xAg-yCu solders and Cu substrate

    NASA Astrophysics Data System (ADS)

    Huang, M. L.; Yang, F.

    2014-11-01

    The downsizing of solder balls results in larger interfacial intermetallic compound (IMC) grains and less Cu substrate consumption in lead-free soldering on Cu substrates. This size effect on the interfacial reaction is experimentally demonstrated and theoretically analyzed using Sn-3.0Ag-0.5Cu and Sn-3.5Ag solder balls. The interfacial reaction between the Sn-xAg-yCu solders and Cu substrates is a dynamic response to a combination of effects of interfacial IMC growth, Cu substrate consumption and composition variation in the interface zone. A concentration gradient controlled (CGC) kinetics model is proposed to explain the combined effects. The concentration gradient of Cu at the interface, which is a function of solder volume, initial Cu concentration and reaction time, is the root cause of the size effect. We found that a larger Cu concentration gradient results in smaller Cu6Sn5 grains and more consumption of Cu substrate. According to our model, the growth kinetics of interfacial Cu6Sn5 obeys a t1/3 law when the molten solder has approached the solution saturation, and will be slower otherwise due to the interfering dissolution mechanism. The size effect introduced in this model is supported by a good agreement between theoretical and experimental results. Finally, the scope of application of this model is discussed.

  15. Size effect model on kinetics of interfacial reaction between Sn-xAg-yCu solders and Cu substrate

    PubMed Central

    Huang, M. L.; Yang, F.

    2014-01-01

    The downsizing of solder balls results in larger interfacial intermetallic compound (IMC) grains and less Cu substrate consumption in lead-free soldering on Cu substrates. This size effect on the interfacial reaction is experimentally demonstrated and theoretically analyzed using Sn-3.0Ag-0.5Cu and Sn-3.5Ag solder balls. The interfacial reaction between the Sn-xAg-yCu solders and Cu substrates is a dynamic response to a combination of effects of interfacial IMC growth, Cu substrate consumption and composition variation in the interface zone. A concentration gradient controlled (CGC) kinetics model is proposed to explain the combined effects. The concentration gradient of Cu at the interface, which is a function of solder volume, initial Cu concentration and reaction time, is the root cause of the size effect. We found that a larger Cu concentration gradient results in smaller Cu6Sn5 grains and more consumption of Cu substrate. According to our model, the growth kinetics of interfacial Cu6Sn5 obeys a t1/3 law when the molten solder has approached the solution saturation, and will be slower otherwise due to the interfering dissolution mechanism. The size effect introduced in this model is supported by a good agreement between theoretical and experimental results. Finally, the scope of application of this model is discussed. PMID:25408359

  16. Size effect model on kinetics of interfacial reaction between Sn-xAg-yCu solders and Cu substrate.

    PubMed

    Huang, M L; Yang, F

    2014-01-01

    The downsizing of solder balls results in larger interfacial intermetallic compound (IMC) grains and less Cu substrate consumption in lead-free soldering on Cu substrates. This size effect on the interfacial reaction is experimentally demonstrated and theoretically analyzed using Sn-3.0Ag-0.5Cu and Sn-3.5Ag solder balls. The interfacial reaction between the Sn-xAg-yCu solders and Cu substrates is a dynamic response to a combination of effects of interfacial IMC growth, Cu substrate consumption and composition variation in the interface zone. A concentration gradient controlled (CGC) kinetics model is proposed to explain the combined effects. The concentration gradient of Cu at the interface, which is a function of solder volume, initial Cu concentration and reaction time, is the root cause of the size effect. We found that a larger Cu concentration gradient results in smaller Cu(6)Sn(5) grains and more consumption of Cu substrate. According to our model, the growth kinetics of interfacial Cu(6)Sn(5) obeys a t(1/3) law when the molten solder has approached the solution saturation, and will be slower otherwise due to the interfering dissolution mechanism. The size effect introduced in this model is supported by a good agreement between theoretical and experimental results. Finally, the scope of application of this model is discussed. PMID:25408359

  17. Enhanced waveguide-type ultraviolet electroluminescence from ZnO/MgZnO core/shell nanorod array light-emitting diodes via coupling with Ag nanoparticles localized surface plasmons

    NASA Astrophysics Data System (ADS)

    Zhang, Cen; Marvinney, Claire Elizabeth; Xu, Hai Yang; Liu, Wei Zhen; Wang, Chun Liang; Zhang, Li Xia; Wang, Jian Nong; Ma, Jian Gang; Liu, Yi Chun

    2014-12-01

    Localized surface plasmon (LSP) enhanced waveguide-type ultraviolet light-emitting diodes (LEDs) were fabricated by sputtering Ag nanoparticles (Ag-NPs) onto ZnO/MgZnO core/shell nanorod array (CS-NRA)/p-GaN heterostructures. A ~9-fold enhancement of ZnO ultraviolet electroluminescence (EL) was demonstrated by the Ag-NPs decorated LED compared with the device without Ag-NPs. Angle-dependent EL measurements, as well as finite-difference time-domain simulations of the EL intensity spatial distribution, confirmed the waveguide-type EL transmission mode along the NR's axial direction. The increased spontaneous emission rate observed in time-resolved spectroscopy suggested that the ZnO EL enhancement was attributed to LSP-exciton/polariton coupling. However, a direct coupling is very difficult to achieve between Ag-LSPs and electron-hole pairs in the active region due to their ``remote'' separation. Thereby, two possible models involving the dynamic process of interactions among excitons, photons, and LSPs, were established to understand the selective enhancement of ZnO EL.Localized surface plasmon (LSP) enhanced waveguide-type ultraviolet light-emitting diodes (LEDs) were fabricated by sputtering Ag nanoparticles (Ag-NPs) onto ZnO/MgZnO core/shell nanorod array (CS-NRA)/p-GaN heterostructures. A ~9-fold enhancement of ZnO ultraviolet electroluminescence (EL) was demonstrated by the Ag-NPs decorated LED compared with the device without Ag-NPs. Angle-dependent EL measurements, as well as finite-difference time-domain simulations of the EL intensity spatial distribution, confirmed the waveguide-type EL transmission mode along the NR's axial direction. The increased spontaneous emission rate observed in time-resolved spectroscopy suggested that the ZnO EL enhancement was attributed to LSP-exciton/polariton coupling. However, a direct coupling is very difficult to achieve between Ag-LSPs and electron-hole pairs in the active region due to their ``remote'' separation

  18. Effect of growth time on morphology and photoelectrochemical performance of TiO2 nanorod arrays grown on transparent conducting substrates

    NASA Astrophysics Data System (ADS)

    Sui, Mei-rong; Han, Cui-ping; Gu, Xiu-quan; Wang, Yong; Tang, Lu; Tang, Hui

    2015-11-01

    TiO2 nanorod arrays (NRAs) were synthesized directly on the fluorine tin oxide (FTO) coated glass substrates by a facile hydrothermal route. The effects of growth time on the photoelectrochemical (PEC) properties of TiO2 NRAs are investigated. The samples synthesized for 4 h exhibit a photocurrent intensity of 0.37 mA/cm2 at the irradiation of Xe lamp and a bias of 0 V. As the growth time increases, the thickness and order degree of the NRAs are enhanced, but the photocurrent is reduced a lot. It might be associated with the hindering of a high background electron density in NRs due to the long-time hydrothermal reaction in acid environment. Moreover, the decline behavior is observed, which is attributed to the poor charge separation capacity of TiO2 array electrodes and could be suppressed efficiently by applying a suitable positive bias.

  19. Ag-nanoparticles on UF-microsphere as an ultrasensitive SERS substrate with unique features for rhodamine 6G detection.

    PubMed

    Hao, Zhixian; Mansuer, Mulati; Guo, Yuqing; Zhu, Zhirong; Wang, Xiaogang

    2016-01-01

    Urea and formaldehyde (UF) microsphere (MS) adsorbing Ag nanoparticles (NPs) was employed as a surface enhanced Raman scattering (SERS) substrate for rhodamine 6G (R6G) detection. The UF MSs and citrate-reduced Ag colloid supplying Ag NPs are synthesized separately and all the subsequent fabrication procedure is then implemented within 2 mL centrifuge tube. Influences of the composition and drying temperature of the UF MSs and the drying method and modification of AgNP/UFMS on the final SERS performance have first been reported. Excess formaldehyde useful in the formation of UF MSs again plays an important role in the SERS detection. Some interesting phenomena in the approach, such as swelling/deswelling of UF MSs and R6G diffusion within hydrophilic environment of UF MSs, are found to be of variable factors affecting the SERS performance. The substrate AgNP/UFMS confidently achieves a detection limit of 10(-13) M R6G and can be used as a simple and effective platform in the SERS spectroscopy. PMID:26695301

  20. Mirroring the dynamic magnetic behavior of magnetostrictive Co/(Ag,Cu,Ta) multilayers grown onto rigid and flexible substrates

    NASA Astrophysics Data System (ADS)

    Agra, K.; Gomes, R. R.; Della Pace, R. D.; Dorneles, L. S.; Bohn, F.; Corrêa, M. A.

    2015-11-01

    We investigate the magnetoimpedance effect in a wide frequency range in magnetostrictive Co/(Ag,Cu,Ta) multilayers grown onto rigid and flexible substrates. We observe a direct correlation between structural and quasi-static magnetic properties and the magnetoimpedance effect, since they are directly dependent on the nature of the spacer material. Moreover, we verify that all these properties are insensitive to the kind of employed substrate. We compare the magnetoimpedance results measured for multilayers in rigid and flexible substrates and discuss them in terms of different mechanisms that govern the impedances changes, magnetic anisotropy, structural character, and of numerical calculation results found in the literature. The fact that magnetostrictive multilayers can be reproduced in distinct kinds of substrates corresponds to an important advance for their applicability. The results place multilayers grown onto flexible substrates as attractive candidates for application as probe element in the development of MI-based sensor devices.

  1. The demonstration of hybrid n-ZnO nanorod/p-polymer heterojunction light emitting diodes on glass substrates

    NASA Astrophysics Data System (ADS)

    Wadeasa, A.; Beegum, S. L.; Raja, S.; Nur, O.; Willander, M.

    2009-06-01

    We report a demonstration of heterojunction light emitting diode (LED) based on a hybrid n-ZnO-nanorod/p-polymer layered structure. The ZnO was grown using the aqueous chemical growth (ACG) on top of the polymer(s) which were deposited on glass. The current-voltage (I-V) behavior of the heterojunctions showed good rectifying diode characteristics. Room-temperature electroluminescence (EL) spectra of the LEDs provided a broad emission band over a wide LED color range (430-650 nm), in which both zinc and oxygen vacancy peaks are clearly detected. We present here luminescent devices based on the use of ZnO-nanorods in combination with two different blended and multi-layered p-type polymers. Electroluminescence of the first batch of devices showed that white bluish strong emission for the presently used polymers is clearly observed. We obtained a turn-on voltage of 3 V and break-down voltage equal to -6 V for PVK-TFB blended device. The corresponding values for the NPD-PFO multilayer device were 4 V and -14 V, respectively. The rectification factors were equal to 3 and 10 for the two devices, respectively. The films and devices processed were characterized by scanning electron microscopy (SEM), DEKTAK 3ST Surface Profile, Semiconductor Parameter Analyzer, photoluminescence (PL), and electroluminescence (EL).

  2. Microwave sintering of Ag-nanoparticle thin films on a polyimide substrate

    SciTech Connect

    Fujii, S.; Kawamura, S.; Maitani, M. M.; Suzuki, E.; Wada, Y.; Mochizuki, D.

    2015-12-15

    Ag-nanoparticle thin films on a polyimide substrate were subjected to microwave sintering by use of a single-mode waveguide applicator. A two-step sintering process was employed. First, at low conductivities of the film, the film sample was placed at the site of the maximum electric field and subjected to microwave irradiation. Second, when the conductivity of the film increased, the film sample was placed at the site of the maximum magnetic field and again subjected to microwave irradiation. The microwave sintering process was completed within 1.5 min, which is significantly lower than the time required for the oven heating process. The resulting conductivity of the film, albeit only 30% of that of the bulk material, was seven times that of a film annealed at the same temperature in a furnace. Scanning electron microscopy images revealed that the nanoparticles underwent both grain necking and grain growth during microwave sintering. In addition, this sintering process was equivalent to the oven heating process performed at a 50 °C higher annealing temperature. An electromagnetic wave simulation and a heat transfer simulation of the microwave sintering process were performed to gain a thorough understanding of the process.

  3. High efficiency single Ag nanowire/p-GaN substrate Schottky junction-based ultraviolet light emitting diodes

    SciTech Connect

    Wu, Y.; Li, X.; Xu, P.; Wang, Y.; Shen, X.; Liu, X.; Yang, Q.; Hasan, T.

    2015-02-02

    We report a high efficiency single Ag nanowire (NW)/p-GaN substrate Schottky junction-based ultraviolet light emitting diode (UV-LED). The device demonstrates deep UV free exciton electroluminescence at 362.5 nm. The dominant emission, detectable at ultralow (<1 μA) forward current, does not exhibit any shifts when the forward current is increased. External quantum efficiency (EQE) as high as 0.9% is achieved at 25 μA current at room temperature. Experiments and simulation analysis show that devices fabricated with thinner Ag NWs have higher EQE. However, for very thin Ag NWs (diameter < 250 nm), this trend breaks down due to heat accumulation in the NWs. Our simple device architecture offers a potentially cost-effective scheme to fabricate high efficiency Schottky junction-based UV-LEDs.

  4. Immunoassay for tumor markers in human serum based on Si nanoparticles and SiC@Ag SERS-active substrate.

    PubMed

    Zhou, Lu; Zhou, Jun; Feng, Zhao; Wang, Fuyan; Xie, Shushen; Bu, Shizhong

    2016-04-21

    Based on a sandwich structure consisting of nano-Si immune probes and a SiC@Ag SERS-active immune substrate, a kind of ultra-sensitive immunoassay protocol is presented to detect tumor markers in human serum. The nano-Si immune probes were prepared by immobilizing the detecting antibodies onto the surfaces of SiO2-coated Si nanoparticles (NPs) which were modified with 3-(aminopropyl)trimethoxysilane, and the SiC@Ag SERS-active immune substrates were prepared by immobilizing the captured antibodies on Ag film sputtered on SiC sandpaper. To the best of our knowledge, it is the first time that Si NPs are directly used as Raman tags in an immunoassay strategy. And, the SiC@Ag SERS-active substrates exhibit excellent surface enhanced Raman scattering (SERS) performances with an enhancement factor of ∼10(5), owing to the plasmonic effect of the Ag film on the rough surface of the SiC sandpaper. In our experiments, the sandwich immunoassay structure has been successfully applied to detect prostate specific antigen (PSA), α-fetoprotein (AFP) and carbohydrate antigen 19-9 (CA19-9) in a human serum sample and the limit of detections are as low as 1.79 fg mL(-1), 0.46 fg mL(-1) and 1.3 × 10(-3) U mL(-1), respectively. It reveals that the proposed immunoassay protocol has demonstrated a high sensitivity for tumor markers in human serum and a potential practicability in biosensing and clinical diagnostics. PMID:27003871

  5. Enhanced waveguide-type ultraviolet electroluminescence from ZnO/MgZnO core/shell nanorod array light-emitting diodes via coupling with Ag nanoparticles localized surface plasmons.

    PubMed

    Zhang, Cen; Marvinney, Claire Elizabeth; Xu, Hai Yang; Liu, Wei Zhen; Wang, Chun Liang; Zhang, Li Xia; Wang, Jian Nong; Ma, Jian Gang; Liu, Yi Chun

    2015-01-21

    Localized surface plasmon (LSP) enhanced waveguide-type ultraviolet light-emitting diodes (LEDs) were fabricated by sputtering Ag nanoparticles (Ag-NPs) onto ZnO/MgZnO core/shell nanorod array (CS-NRA)/p-GaN heterostructures. A ∼9-fold enhancement of ZnO ultraviolet electroluminescence (EL) was demonstrated by the Ag-NPs decorated LED compared with the device without Ag-NPs. Angle-dependent EL measurements, as well as finite-difference time-domain simulations of the EL intensity spatial distribution, confirmed the waveguide-type EL transmission mode along the NR's axial direction. The increased spontaneous emission rate observed in time-resolved spectroscopy suggested that the ZnO EL enhancement was attributed to LSP-exciton/polariton coupling. However, a direct coupling is very difficult to achieve between Ag-LSPs and electron-hole pairs in the active region due to their "remote" separation. Thereby, two possible models involving the dynamic process of interactions among excitons, photons, and LSPs, were established to understand the selective enhancement of ZnO EL. PMID:25475883

  6. Ag-nanoparticle-decorated porous ZnO-nanosheets grafted on a carbon fiber cloth as effective SERS substrates

    NASA Astrophysics Data System (ADS)

    Wang, Zhiwei; Meng, Guowen; Huang, Zhulin; Li, Zhongbo; Zhou, Qitao

    2014-11-01

    We report on the large-scale synthesis of Ag-nanoparticle (Ag-NP) decorated ZnO-mesoporous-nanosheets (NSs) grafted on a flexible carbon fiber cloth (CFC), as sensitive and reproducible surface enhanced Raman scattering (SERS) substrates with excellent flexibility. The composite SERS-substrates are achieved by a combination of atomic layer deposition of ZnO-seeds on each fiber of the CFC (denoted as ZnO-seeds@CFC), chemical bath deposition and subsequent pyrolysis for the creation of ZnO-mesoporous-NSs grafted on ZnO-seeds@CFC, and ion-sputtering of Ag-NPs on the ZnO-mesoporous-NSs. As abundant SERS ``hot spots'' are generated from the electromagnetic coupling of the densely distributed Ag-NPs, and the semiconducting ZnO-mesoporous-NSs also have chemical supporting enhancement and distinct molecule adsorbing abilities, the composite SERS-substrates demonstrate high SERS-sensitivity with good signal reproducibility. As a trial for potential applications, the composite SERS-substrates were used to identify pesticides and highly toxic polychlorinated biphenyls (PCBs), and low concentrations down to 10-7 M for methyl parathion and 5 × 10-6 M for PCB-77 were reached, respectively, showing promising potential for the SERS-based rapid detection of toxic organic pollutants in the environment.We report on the large-scale synthesis of Ag-nanoparticle (Ag-NP) decorated ZnO-mesoporous-nanosheets (NSs) grafted on a flexible carbon fiber cloth (CFC), as sensitive and reproducible surface enhanced Raman scattering (SERS) substrates with excellent flexibility. The composite SERS-substrates are achieved by a combination of atomic layer deposition of ZnO-seeds on each fiber of the CFC (denoted as ZnO-seeds@CFC), chemical bath deposition and subsequent pyrolysis for the creation of ZnO-mesoporous-NSs grafted on ZnO-seeds@CFC, and ion-sputtering of Ag-NPs on the ZnO-mesoporous-NSs. As abundant SERS ``hot spots'' are generated from the electromagnetic coupling of the densely

  7. Effective electrocatalysis based on Ag2O nanowire arrays supported on a copper substrate.

    PubMed

    Ji, Rong; Wang, Lingling; Yu, Liutao; Geng, Baoyou; Wang, Guangfeng; Zhang, Xiaojun

    2013-11-13

    Silver oxide nanowire arrays (Ag2O NWAs) were first synthesized on a copper (Cu) rod by a simple and facile wet-chemistry approach without using any surfactants. The as-synthesized Ag2O NWA/Cu rod not only can be used as an integrated electrode (called a Ag2O NWA/CRIE) to detect hydrazine (HZ) but also can serve as the catalyst layer for a direct HZ fuel cell. The current density of HZ oxidation on Ag2O NWA (94.4 mA cm(-2)) is much bigger than that on a bare Cu rod (3.9 mA cm(-2)) at -0.6 V, and other Ag2O NWAs have the lowest onset potential (-0.85 V). This suggests that a Ag2O NWA integrated electrode has potential application in catalytic fields that contain the HZ fuel cell. PMID:23978111

  8. Enhancing UV-emissions through optical and electronic dual-function tuning of Ag nanoparticles hybridized with n-ZnO nanorods/p-GaN heterojunction light-emitting diodes

    NASA Astrophysics Data System (ADS)

    Yao, Yung-Chi; Yang, Zu-Po; Hwang, Jung-Min; Chuang, Yi-Lun; Lin, Chia-Ching; Haung, Jing-Yu; Chou, Chun-Yang; Sheu, Jinn-Kong; Tsai, Meng-Tsan; Lee, Ya-Ju

    2016-02-01

    ZnO nanorods (NRs) and Ag nanoparticles (NPs) are known to enhance the luminescence of light-emitting diodes (LEDs) through the high directionality of waveguide mode transmission and efficient energy transfer of localized surface plasmon (LSP) resonances, respectively. In this work, we have demonstrated Ag NP-incorporated n-ZnO NRs/p-GaN heterojunctions by facilely hydrothermally growing ZnO NRs on Ag NP-covered GaN, in which the Ag NPs were introduced and randomly distributed on the p-GaN surface to excite the LSP resonances. Compared with the reference LED, the light-output power of the near-band-edge (NBE) emission (ZnO, λ = 380 nm) of our hybridized structure is increased almost 1.5-2 times and can be further modified in a controlled manner by varying the surface morphology of the surrounding medium of the Ag NPs. The improved light-output power is mainly attributed to the LSP resonance between the NBE emission of ZnO NRs and LSPs in Ag NPs. We also observed different behaviors in the electroluminescence (EL) spectra as the injection current increases for the treatment and reference LEDs. This observation might be attributed to the modification of the energy band diagram for introducing Ag NPs at the interface between n-ZnO NRs and p-GaN. Our results pave the way for developing advanced nanostructured LED devices with high luminescence efficiency in the UV emission regime.ZnO nanorods (NRs) and Ag nanoparticles (NPs) are known to enhance the luminescence of light-emitting diodes (LEDs) through the high directionality of waveguide mode transmission and efficient energy transfer of localized surface plasmon (LSP) resonances, respectively. In this work, we have demonstrated Ag NP-incorporated n-ZnO NRs/p-GaN heterojunctions by facilely hydrothermally growing ZnO NRs on Ag NP-covered GaN, in which the Ag NPs were introduced and randomly distributed on the p-GaN surface to excite the LSP resonances. Compared with the reference LED, the light-output power of the

  9. Intermetallic compounds formed at the interface between Cu substrate and an Sn-9Zn-0.5Ag lead-free solder

    SciTech Connect

    Chang, T.-C.; Hon, M.-H.; Wang, M.-C

    2003-04-30

    The intermetallic compounds (IMCs) formed at the interface between Cu substrate and an Sn-9Zn-0.5Ag lead-free solder alloy have been investigated by X-ray diffraction (XRD), transmission electron microscopy (TEM) and electron diffraction (ED). The XRD patterns show that the main IMCs formed at the interface of Sn-9Zn-0.5Ag/Cu are {gamma}-Cu{sub 5}Zn{sub 8} and {eta}'-Cu{sub 6}Sn{sub 5}. The Ag{sub 3}Sn IMC with orthorhombic structure was also observed at the Sn-9Zn-0.5Ag/Cu interface by TEM and ED analyses. The interfacial adhesion strength between the Cu substrate and Sn-9Zn-0.5Ag lead-free solder alloy is higher than that of the Sn-9Zn alloy due to the formation of Ag{sub 3}Sn IMC at the interface.

  10. Enhancing UV-emissions through optical and electronic dual-function tuning of Ag nanoparticles hybridized with n-ZnO nanorods/p-GaN heterojunction light-emitting diodes.

    PubMed

    Yao, Yung-Chi; Yang, Zu-Po; Hwang, Jung-Min; Chuang, Yi-Lun; Lin, Chia-Ching; Haung, Jing-Yu; Chou, Chun-Yang; Sheu, Jinn-Kong; Tsai, Meng-Tsan; Lee, Ya-Ju

    2016-02-28

    ZnO nanorods (NRs) and Ag nanoparticles (NPs) are known to enhance the luminescence of light-emitting diodes (LEDs) through the high directionality of waveguide mode transmission and efficient energy transfer of localized surface plasmon (LSP) resonances, respectively. In this work, we have demonstrated Ag NP-incorporated n-ZnO NRs/p-GaN heterojunctions by facilely hydrothermally growing ZnO NRs on Ag NP-covered GaN, in which the Ag NPs were introduced and randomly distributed on the p-GaN surface to excite the LSP resonances. Compared with the reference LED, the light-output power of the near-band-edge (NBE) emission (ZnO, λ = 380 nm) of our hybridized structure is increased almost 1.5-2 times and can be further modified in a controlled manner by varying the surface morphology of the surrounding medium of the Ag NPs. The improved light-output power is mainly attributed to the LSP resonance between the NBE emission of ZnO NRs and LSPs in Ag NPs. We also observed different behaviors in the electroluminescence (EL) spectra as the injection current increases for the treatment and reference LEDs. This observation might be attributed to the modification of the energy band diagram for introducing Ag NPs at the interface between n-ZnO NRs and p-GaN. Our results pave the way for developing advanced nanostructured LED devices with high luminescence efficiency in the UV emission regime. PMID:26852753

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

    NASA Astrophysics Data System (ADS)

    Dikovska, A. Og.; Atanasova, G. B.; Avdeev, G. V.; Nedyalkov, N. N.

    2016-06-01

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

  12. Facile synthesis of large-scale Ag nanosheet-assembled films with sub-10 nm gaps as highly active and homogeneous SERS substrates

    NASA Astrophysics Data System (ADS)

    Li, Zhongbo; Meng, Guowen; Liang, Ting; Zhang, Zhuo; Zhu, Xiaoguang

    2013-01-01

    We report a facile low-cost synthetic approach to large-scale Ag nanosheet-assembled films with a high density of uniformly distributed sub-10 nm gaps between the adjacent nanosheets on Si substrates via galvanic cell reactions. The distribution density of Ag nanosheets on substrates could be tailored by tuning the duration of the HF-etching and the concentration of citric acid in the solution. Furthermore, in conjunction with a conventional photolithography, highly uniform patterned Ag nanosheet-assembled structures with different morphologies can be achieved on Si substrates via galvanic-cell-induced growth. By using rhodamine 6G as a standard test molecule, the large-scale Ag nanosheet-assembled films exhibit highly active and homogenous surface-enhanced Raman scattering (SERS) effect and also show promising potentials as reliable SERS substrates for rapid detection of trace polychlorinated biphenyls (PCBs).

  13. Bi-SERS sensing and enhancement by Au-Ag bimetallic non-alloyed nanoparticles on amorphous and crystalline silicon substrate.

    PubMed

    Tan, Chee Leong; Lee, Soo Kyung; Lee, Yong Tak

    2015-03-01

    We have demonstrated Au-Ag bimetallic non-alloy nanoparticles (BNNPs) on thin a-Si film and c-Si substrate for high SERS enhancement, low cost, high sensitivity and reproducible SERS substrate with bi-SERS sensing properties where two different SERS peak for Au NPs and Ag NPs are observed on single SERS substrate. The isolated Au-Ag bimetallic NPs, with uniform size and spacing distribution, are suitable for uniform high density hotspot SERS enhancement. The SERS enhancement factor of Au-Ag BNNPs is 2.9 times higher compared to Ag NPs on similar substrates due to the increase of the localized surface plasmon resonance effect. However there is a decrement of SERS peak intensity at specific wavenumbers when the surrounding refractive index increases due to out-phase hybridization of Au NPs. The distinct changes of the two different SERS peaks on single Au-Ag BNNPs SERS substrate due to Au and Ag NPs independently show possible application for bi-molecular sensing. PMID:25836846

  14. Plasmon-Driven Dynamic Response of a Hierarchically Structural Silver-Decorated Nanorod Array for Sub-10 nm Nanogaps.

    PubMed

    Wang, Yi; Wang, Hailong; Wang, Yuyang; Shen, Yanting; Xu, Shuping; Xu, Weiqing

    2016-06-22

    Plasmonic nanogaps serve as a useful configuration for light concentration and local field amplification owing to the extreme localization of surface plasmons. Here, a smart plasmonic nanogap device is fabricated by the dynamic response of an Ag decorated hierarchically structural vertical polymer nanorod array under the light irradiation. Seven nanorods in one unit bend because of plasmonic heating effect and they are centrally collected due to the attraction of the plasmon-induced polaritons, leading to the significantly enhanced local electromagnetic field at the sub-10 nm gaps among the constricted nanorod tops. Compared with tuning capillarity in microscale by wetting and drying, using light as external stimuli is much easier and more tunable in nanoscale. This plasmonic nanogap device is used for a surface-enhanced Raman scattering (SERS) substrate. Its hydrophobic surface with a contact angle of 142 degree can make the probed aqueous solution only access to the Ag tips of nanorods. Thus, the analytes can be driven to the "hot spot" regions where located at the tops of nanorods during the solvent evaporation process, which is beneficial to SERS detection. Discovery of this smart plasmon-driven process broadens the scope for further functionality of both the dynamic nanostructure design and the smart plasmonic devices in the communities of chemistry, biomedicine, and microfluidic engineering. PMID:27250862

  15. Silicon nanowire arrays coated with electroless Ag for increased surface-enhanced Raman scattering

    NASA Astrophysics Data System (ADS)

    Bai, Fan; Li, Meicheng; Fu, Pengfei; Li, Ruike; Gu, Tiansheng; Huang, Rui; Chen, Zhao; Jiang, Bing; Li, Yingfeng

    2015-05-01

    The ordered Ag nanorod (AgNR) arrays are fabricated through a simple electroless deposition technique using the isolated Si nanowire (SiNW) arrays as the Ag-grown scaffold. The AgNR arrays have the single-crystallized structure and the plasmonic crystal feature. It is found that the formation of the AgNR arrays is strongly dependent on the filling ratio of SiNWs. A mechanism is proposed based on the selective nucleation and the synergistic growth of Ag nanoparticles on the top of the SiNWs. Moreover, the special AgNR arrays grown on the substrate of SiNWs exhibit a detection sensitivity of 10-15M for rhodamine 6G molecules, which have the potential application to the highly sensitive surface-enhanced Raman scattering sensors.

  16. Near Room Temperature, Fast-Response, and Highly Sensitive Triethylamine Sensor Assembled with Au-Loaded ZnO/SnO₂ Core-Shell Nanorods on Flat Alumina Substrates.

    PubMed

    Ju, Dian-Xing; Xu, Hong-Yan; Qiu, Zhi-Wen; Zhang, Zi-Chao; Xu, Qi; Zhang, Jun; Wang, Jie-Qiang; Cao, Bing-Qiang

    2015-09-01

    Chemiresistive gas sensors with low power consumption, fast response, and reliable fabrication process for a specific target gas have been now created for many applications. They require both sensitive nanomaterials and an efficient substrate chip for heating and electrical addressing. Herein, a near room working temperature and fast response triethylamine (TEA) gas sensor has been fabricated successfully by designing gold (Au)-loaded ZnO/SnO2 core-shell nanorods. ZnO nanorods grew directly on Al2O3 flat electrodes with a cost-effective hydrothermal process. By employing pulsed laser deposition (PLD) and DC-sputtering methods, the construction of Au nanoparticle-loaded ZnO/SnO2 core/shell nanorod heterostructure is highly controllable and reproducible. In comparison with pristine ZnO, SnO2, and Au-loaded ZnO, SnO2 sensors, Au-ZnO/SnO2 nanorod sensors exhibit a remarkably high and fast response to TEA gas at working temperatures as low as 40 °C. The enhanced sensing property of the Au-ZnO/SnO2 sensor is also discussed with the semiconductor depletion layer model introduced by Au-SnO2 Schottky contact and ZnO/SnO2 N-N heterojunction. PMID:26280916

  17. Study on deposition technique and properties of Pd/Ag alloy film sensor supported on ceramic substrate

    NASA Astrophysics Data System (ADS)

    Geng, Z. T.; He, Q.; Jin, C. G.

    2016-07-01

    Developing high-quality hydrogen sensitive material is the core part of hydrogen sensor, whose performance is determined by the sensitive response, reproducibility and recovery of hydrogen material etc. In order to overcome the defects of hydrogen embrittlement in previous hydrogen sensor which were based on the pure palladium, sliver as the second component added to the palladium was studied. Using photochemical etching technology to produce a bent metal mask, the mask is put on the ceramic substrate. Firstly, the thin film of Ta2O5 as a transition layer grew on the ceramic substrate. Then, a series of Pd/Ag alloy film sensors were prepared, and each performance characterization of Pd/Ag alloy film was studied. Testing results indicated that the thin film had a good linear output performance at 0∼⃒30% hydrogen concentration range, and demonstrates a high responsiveness and good repeatability. With temperature increasing, the strength of the responsive signal of the Pd/Ag alloy film decreases and its responsive time was also shortened.

  18. Memristive switching of ZnO nanorod mesh

    NASA Astrophysics Data System (ADS)

    Yevgeniy, Puzyrev; Shen, Xiao; Ni, Kai; Zhang, Xuan; Hachtel, Jordan; Choi, Bo; Chisholm, Matthew; Fleetwood, Daniel; Schrimpf, Ronald; Pantelides, Sokrates

    We present a combined experimental and theoretical study of memristive switching in a self-assembled mesh of ZnO nanorods. A ZnO nanorod mesh spans the area between Ag contacts in a device that exhibits hysteresis with large ON/OFF ratio, reaching ION/IOFF values of 104. We show that switching behavior depends critically on the geometry of the nanorod mesh. We employ density functional theory (DFT) calculations to deduce the mechanism for resistive switching for the nanorod mesh. Redistribution of Ag atoms, driven by an electrical field, leads to the formation and evolution of a conducting path through nanorods. Field-induced migration of Ag atoms changes the doping level of nanorods and modulates their conductivity. Using static DFT and nudged-elastic-band calculations, we investigate the energy of interaction between Ag clusters and a ZnO surface, including migration barriers of Ag atoms. Current-voltage (I-V) characteristics are modeled using percolation theory in a nanorod mesh. To describe the dynamics of SET/RESET phenomena, model parameters include the experimentally observed nanorod geometry and the energetics of Ag on ZnO surfaces, obtained from DFT calculations. This work was supported by NSF Grant DMR-1207241, DOE Grant DE-FG02-09ER46554, and the McMinn Endowment at Vanderbilt University. Computational support was provided by the NSF XSEDE under Grant #DMR TG-DMR130121.

  19. Gold coated ZnO nanorod biosensor for glucose detection

    NASA Astrophysics Data System (ADS)

    Bhattacharya, Anuradha; Jain, Chhavi; Rao, V. Padmanapan; Banerjee, S.

    2012-06-01

    Gold coated ZnO nanorod based biosensor has been fabricated for its glucose detecting abilities and compared with that of ZnO nanorod based biosensor. SEM images of electrochemically grown ZnO nanorods show hexagonally grown ZnO nanorods on an ITO substrate. Electrochemical analysis show that gold coated ZnO based biosensors have higher sensitivity, lower limit of detection and a wider linear range for glucose detection. The results demonstrate that gold coated ZnO nanorod based biosensors are a promising material for biosensor applications over single component ZnO nanorod based biosensor.

  20. Annealing effects on the optical and morphological properties of ZnO nanorods on AZO substrate by using aqueous solution method at low temperature

    PubMed Central

    2014-01-01

    Vertically aligned ZnO nanorods (NRs) on aluminum-doped zinc oxide (AZO) substrates were fabricated by a single-step aqueous solution method at low temperature. In order to optimize optical quality, the effects of annealing on optical and structural properties were investigated by scanning electron microscopy, X-ray diffraction, photoluminescence (PL), and Raman spectroscopy. We found that the annealing temperature strongly affects both the near-band-edge (NBE) and visible (defect-related) emissions. The best characteristics have been obtained by employing annealing at 400°C in air for 2 h, bringing about a sharp and intense NBE emission. The defect-related recombinations were also suppressed effectively. However, the enhancement decreases with higher annealing temperature and prolonged annealing. PL study indicates that the NBE emission is dominated by radiative recombination associated with hydrogen donors. Thus, the enhancement of NBE is due to the activation of radiative recombinations associated with hydrogen donors. On the other hand, the reduction of visible emission is mainly attributed to the annihilation of OH groups. Our results provide insight to comprehend annealing effects and an effective way to improve optical properties of low-temperature-grown ZnO NRs for future facile device applications. PMID:25520589

  1. High Ms Fe16N2 thin film with Ag under layer on GaAs substrate

    NASA Astrophysics Data System (ADS)

    Zhang, Xiaowei; Jiang, Yanfeng; Yang, Meiyin; Allard, Lawrence F.; Wang, Jian-Ping

    2016-05-01

    (001) textured Fe16N2 thin film with Ag under layer is successfully grown on GaAs substrate using a facing target sputtering (FTS) system. After post annealing, chemically ordered Fe16N2 phase is formed and detected by X-ray diffraction (XRD). High saturation magnetization (Ms) is measured by a vibrating sample magnetometer (VSM). In comparison with Fe16N2 with Ag under layer on MgO substrate and Fe16N2 with Fe under layer on GaAs substrate, the current layer structure shows a higher Ms value, with a magnetically softer feature in contrast to the above cases. In addition, X-ray photoelectron spectroscopy (XPS) is performed to characterize the binding energy of N atoms. To verify the role of strain that the FeN layer experiences in the above three structures, Grazing Incidence X-ray Diffraction (GIXRD) is conducted to reveal a large in-plane lattice constant due to the in-plane biaxial tensile strain.

  2. Hypothalamic AgRP-neurons control peripheral substrate utilization and nutrient partitioning

    PubMed Central

    Joly-Amado, Aurélie; Denis, Raphaël G P; Castel, Julien; Lacombe, Amélie; Cansell, Céline; Rouch, Claude; Kassis, Nadim; Dairou, Julien; Cani, Patrice D; Ventura-Clapier, Renée; Prola, Alexandre; Flamment, Melissa; Foufelle, Fabienne; Magnan, Christophe; Luquet, Serge

    2012-01-01

    Obesity-related diseases such as diabetes and dyslipidemia result from metabolic alterations including the defective conversion, storage and utilization of nutrients, but the central mechanisms that regulate this process of nutrient partitioning remain elusive. As positive regulators of feeding behaviour, agouti-related protein (AgRP) producing neurons are indispensible for the hypothalamic integration of energy balance. Here, we demonstrate a role for AgRP-neurons in the control of nutrient partitioning. We report that ablation of AgRP-neurons leads to a change in autonomic output onto liver, muscle and pancreas affecting the relative balance between lipids and carbohydrates metabolism. As a consequence, mice lacking AgRP-neurons become obese and hyperinsulinemic on regular chow but display reduced body weight gain and paradoxical improvement in glucose tolerance on high-fat diet. These results provide a direct demonstration of a role for AgRP-neurons in the coordination of efferent organ activity and nutrient partitioning, providing a mechanistic link between obesity and obesity-related disorders. PMID:22990237

  3. Effect of wettability on surface morphologies and optical properties of Ag thin films grown on glass and polymer substrates by thermal evaporation

    NASA Astrophysics Data System (ADS)

    Lv, Jing

    2013-05-01

    A series of Ag films with different thicknesses were deposited on BK-7 glass, PET and PC substrates under identical conditions by thermal evaporation. The effect of the wettability on the morphology and optical properties of Ag/glass and Ag/polymer films was studied by atomic force microscopy and spectrophotometry. The experimental results show that the wettability of Ag grains with polymer is stronger than with glass, which results in the aggregation of bigger grains in initial layer. During deposition the interaction of interlayer plays an important role for the formation of the surface morphology. The strong wettability activates the nonlinear optical properties of Ag grains grown on polymer substrates, which result in the strong absorbance in short wavelength. The effect of the bare substrate on the transmittance of Ag films is more obvious than the reflectance. With the increasing of the thickness, the effect of the wettability on the morphology and optical properties of Ag films decline. In this experiment when the thickness is above 50 nm, the effect almost vanished.

  4. Large-scale uniform Ag-NW tip array with enriched sub-10-nm gaps as SERS substrate for rapid determination of trace PCB77

    NASA Astrophysics Data System (ADS)

    Xu, Wei; Meng, Guowen; Huang, Qing; Hu, Xiaoye; Huang, Zhulin; Tang, Haibin; Zhang, Junxi

    2013-04-01

    Ag-nanowire (Ag-NW) tip arrays with high density sub-10-nm gaps have been achieved via anodic aluminum oxide (AAO) template-assistant approach, and exhibit superior surface enhanced Raman scattering (SERS) performance. The Ag-NW tip arrays were fabricated via the following procedures. Firstly, the pore walls of the AAO were thinned to the sub-10-nm scale, and then a layer of Ag thin film was deposited on the AAO via silver mirror reaction. Subsequently, a layer of gold (Au) film was coated on the Ag film via ion-beam evaporation to serve as the electrode for the electrodeposition growth of Ag-NWs. Finally, the Ag-NW tip arrays with sub-10-nm gaps were exposed from the AAO template by physical milling and a subsequent chemical etching. The SERS activity of the as-fabricated substrate is verified by measuring the probe molecules of R6G and polychlorinated biphenyls (PCBs). To further improve the detection sensitivity for PCBs, the substrate was modified with β-cyclodextrin to increase its efficiency of capturing PCBs molecules. As a result, the as-fabricated SERS substrate can be utilized to measure trace 3,3',4,4'-tetrachlorinated biphenyls (PCB77) with a concentration as low as 1 × 10-10 M.

  5. Growth of metal-semiconductor core-multishell nanorods with optimized field confinement and nonlinear enhancement.

    PubMed

    Nan, Fan; Xie, Fang-Ming; Liang, Shan; Ma, Liang; Yang, Da-Jie; Liu, Xiao-Li; Wang, Jia-Hong; Cheng, Zi-Qiang; Yu, Xue-Feng; Zhou, Li; Wang, Qu-Quan; Zeng, Jie

    2016-06-01

    This paper describes a facile method for the synthesis of Au/AuAg/Ag2S/PbS core-multishell nanorods with double trapping layers. The synthesis, in sequence, involved deposition of Ag shells onto the surfaces of Au nanorod seeds, formation of AuAg shells by a galvanic replacement reaction, and overgrowth of the Ag2S shells and PbS shells. The resulting core-multishell nanorod possesses an air gap between the Au core and the AuAg shell. Together with the Ag2S shell, the air gap can efficiently trap light, causing strong field confinement and nonlinear enhancement. The as-prepared Au/AuAg/Ag2S/PbS core-multishell nanorods display distinct localized surface plasmon resonance and nonlinear optical properties, demonstrating an effective pathway for maneuvering the optical properties of nanocavities. PMID:27241031

  6. Diffusion barrier and adhesion properties of SiO(x)N(y) and SiO(x) layers between Ag/polypyrrole composites and Si substrates.

    PubMed

    Horváth, Barbara; Kawakita, Jin; Chikyow, Toyohiro

    2014-06-25

    This paper describes the interface reactions and diffusion between silver/polypyrrole (Ag/PPy) composite and silicon substrate. This composite material can be used as a novel technique for 3D-LSI (large-scale integration) by the fast infilling of through-silicon vias (TSV). By immersion of the silicon wafer with via holes into the dispersed solution of Ag/PPy composite, the holes are filled with the composite. It is important to develop a layer between the composite and the Si substrate with good diffusion barrier and adhesion characteristics. In this paper, SiOx and two types of SiOxNy barrier layers with various thicknesses were investigated. The interface structure between the Si substrate, the barrier, and the Ag/PPy composite was characterized by transmission electron microscopy. The adhesion and diffusion properties of the layers were established for Ag/PPy composite. Increasing thickness of SiOx proved to permit less Ag to transport into the Si substrate. SiOxNy barrier layers showed very good diffusion barrier characteristics; however, their adhesion depended strongly on their composition. A barrier layer composition with good adhesion and Ag barrier properties has been identified in this paper. These results are useful for filling conductive metal/polymer composites into TSV. PMID:24869419

  7. Structural and optical properties of AgAlTe{sub 2} layers grown on sapphire substrates by closed space sublimation method

    SciTech Connect

    Uruno, A. Usui, A.; Kobayashi, M.

    2014-11-14

    AgAlTe{sub 2} layers were grown on a- and c-plane sapphire substrates using a closed space sublimation method. Grown layers were confirmed to be single phase layers of AgAlTe{sub 2} by X-ray diffraction. AgAlTe{sub 2} layers were grown to have a strong preference for the (112) orientation on both kinds of substrates. The variation in the orientation of grown layers was analyzed in detail using the X-ray diffraction pole figure measurement, which revealed that the AgAlTe{sub 2} had a preferential epitaxial relationship with the c-plane sapphire substrate. The atomic arrangement between the (112) AgAlTe{sub 2} layer and sapphire substrates was compared. It was considered that the high order of the lattice arrangement symmetry probably effectively accommodated the lattice mismatch. The optical properties of the grown layer were also evaluated by transmittance measurements. The bandgap energy was found to be around 2.3 eV, which was in agreement with the theoretical bandgap energy of AgAlTe{sub 2}.

  8. Quantitative detection of uric acid by electrochemical-surface enhanced Raman spectroscopy using a multilayered Au/Ag substrate.

    PubMed

    Zhao, Lili; Blackburn, Jonathan; Brosseau, Christa L

    2015-01-01

    Uric acid is a potential important biomarker in urine and serum samples for early diagnosis of preeclampsia, a life-threatening hypertensive disorder that occurs during pregnancy. Preeclampsia is a leading cause of maternal death, especially in developing nation settings. Quantitative detection of uric acid for rapid and routine diagnosis of early preeclampsia using electrochemical-surface enhanced Raman spectroscopy (EC-SERS) is presented herein. A uniform EC-SERS active Au/Ag substrate was developed by depositing nearly monodisperse gold and silver nanoparticles on the carbon working electrode surface of screen printed electrodes. The multilayered Au/Ag substrates were characterized by electron microscopy and used for quantitative detection of uric acid in 0.1 M NaF and synthetic urine at clinically relevant concentrations. These results showed a linear relationship between the EC-SERS signal intensity and the uric acid concentration. Relative errors calculated for selected concentrations were all within the Clinical Laboratory Improvement Amendments (CLIA) criterion for uric acid analysis (±17%). It is believed that routine and early diagnosis of disease could be possible through such quantitative detection of biomarkers in patient samples using this EC-SERS method. PMID:25483146

  9. Substrate-Linked Conformational Change in the Periplasmic Component of a Cu(I)/Ag(I) Efflux System

    SciTech Connect

    Bagai, I.; Liu, W.; Rensing, C.; Blackburn, N.J.; McEvoy, M.M.

    2009-06-02

    Gram-negative bacteria utilize dual membrane resistance nodulation division-type efflux systems to export a variety of substrates. These systems contain an essential periplasmic component that is important for assembly of the protein complex. We show here that the periplasmic protein CusB from the Cus copper/silver efflux system has a critical role in Cu(I) and Ag(I) binding. Isothermal titration calorimetry experiments demonstrate that one Ag(I) ion is bound per CusB molecule with high affinity. X-ray absorption spectroscopy data indicate that the metal environment is an all-sulfur 3-coordinate environment. Candidates for the metal-coordinating residues were identified from sequence analysis, which showed four conserved methionine residues. Mutations of three of these methionine residues to isoleucine resulted in significant effects on CusB metal binding in vitro. Cells containing these CusB variants also show a decrease in their ability to grow on copper-containing plates, indicating an important functional role for metal binding by CusB. Gel filtration chromatography demonstrates that upon binding metal, CusB undergoes a conformational change to a more compact structure. Based on these structural and functional effects of metal binding, we propose that the periplasmic component of resistance nodulation division-type efflux systems plays an active role in export through substrate-linked conformational changes.

  10. Novel One-pot Fabrication of Lab-on-a-Bubble@Ag Substrate without Coupling-agent for Surface Enhanced Raman Scattering

    PubMed Central

    Jiang, Jizhou; Ou-Yang, Lei; Zhu, Lihua; Zou, Jing; Tang, Heqing

    2014-01-01

    Through in-situ reduction of silver nitrate without using any coupling-agent, a substrate for surface-enhanced Raman scattering (SERS) was prepared by coating silver on hollow buoyant silica microspheres as a lab on a bubble (LoB). The silver coated LoBs (LoBs@Ag) floated on surface of a solution could provide a very convenient platform for the detection of target molecules in the solution. The LoBs@Ag substrate not only immobilized well-distributed Ag nanoparticles on the surface LoBs, but excluded the interference of coupling agents. This yielded high-resolution SERS spectra with excellent reproducibility. The adsorption of crystal violet (CV) on the LoBs@Ag substrate was investigated by means of SERS combined with density functional theory (DFT) calculations. The LoBs@Ag substrate exhibited a remarkable Raman enhancement effect for CV with an enhancement factor of 6.9 × 108 and wide adaptability from dye, pesticide to bio-molecules. On the basis of this substrate, a simple and sensitive SERS method was proposed for the determination of trace organic pollutants or bio-molecules. PMID:24487575

  11. Growth of metal-semiconductor core-multishell nanorods with optimized field confinement and nonlinear enhancement

    NASA Astrophysics Data System (ADS)

    Nan, Fan; Xie, Fang-Ming; Liang, Shan; Ma, Liang; Yang, Da-Jie; Liu, Xiao-Li; Wang, Jia-Hong; Cheng, Zi-Qiang; Yu, Xue-Feng; Zhou, Li; Wang, Qu-Quan; Zeng, Jie

    2016-06-01

    This paper describes a facile method for the synthesis of Au/AuAg/Ag2S/PbS core-multishell nanorods with double trapping layers. The synthesis, in sequence, involved deposition of Ag shells onto the surfaces of Au nanorod seeds, formation of AuAg shells by a galvanic replacement reaction, and overgrowth of the Ag2S shells and PbS shells. The resulting core-multishell nanorod possesses an air gap between the Au core and the AuAg shell. Together with the Ag2S shell, the air gap can efficiently trap light, causing strong field confinement and nonlinear enhancement. The as-prepared Au/AuAg/Ag2S/PbS core-multishell nanorods display distinct localized surface plasmon resonance and nonlinear optical properties, demonstrating an effective pathway for maneuvering the optical properties of nanocavities.This paper describes a facile method for the synthesis of Au/AuAg/Ag2S/PbS core-multishell nanorods with double trapping layers. The synthesis, in sequence, involved deposition of Ag shells onto the surfaces of Au nanorod seeds, formation of AuAg shells by a galvanic replacement reaction, and overgrowth of the Ag2S shells and PbS shells. The resulting core-multishell nanorod possesses an air gap between the Au core and the AuAg shell. Together with the Ag2S shell, the air gap can efficiently trap light, causing strong field confinement and nonlinear enhancement. The as-prepared Au/AuAg/Ag2S/PbS core-multishell nanorods display distinct localized surface plasmon resonance and nonlinear optical properties, demonstrating an effective pathway for maneuvering the optical properties of nanocavities. Electronic supplementary information (ESI) available. See DOI: 10.1039/c5nr09151a

  12. Study of the state of Ag and Pd in silver-palladium catalysts on a titanium dioxide substrate by IR spectroscopy of adsorbed CO

    NASA Astrophysics Data System (ADS)

    Kovalenko, N. A.; Sen'ko, T. L.; Petkevich, T. S.; Egiazarov, Yu. G.

    2007-01-01

    We have used IR spectroscopy of adsorbed CO to study the effect of the method for preparation of silver-palladium catalysts on a TiO2 substrate and exposure to an oxidizing or reducing gaseous atmosphere on the state of Ag and Pd centers. We have shown that as a result of the metal-support interaction, the reducibility of the Ag and Pd particles is increased, which leads to a change in their adsorption and catalytic properties.

  13. Solution growth of Ta-doped hematite nanorods for efficient photoelectrochemical water splitting: a tradeoff between electronic structure and nanostructure evolution.

    PubMed

    Fu, Yanming; Dong, Chung-Li; Zhou, Zhaohui; Lee, Wan-Yi; Chen, Jie; Guo, Penghui; Zhao, Liang; Shen, Shaohua

    2016-02-01

    Ta-doped hematite (α-Fe2O3) nanorod array films were successfully prepared on fluorine-doped tin dioxide (FTO) coated glass substrates via a facile solution growth process with TaCl5 as a Ta doping precursor. Under 1 sun illumination and at an applied potential of 1.0 V vs. Ag/AgCl, the Ta-doped α-Fe2O3 photoanode with optimized dopant concentration showed a photocurrent density as high as 0.53 mA cm(-2), which was about 3.5 times higher than that of the undoped sample. As demonstrated by Mott-Schottky and X-ray absorption spectroscopy measurements, considerable increase in photoelectrochemical (PEC) performance achieved for Ta-doped α-Fe2O3 nanorod films should be mainly attributed to the increased electron donor density induced by Ta doping. However, with superfluous Ta doping, the [110]-oriented nanorod structure was destroyed, which caused greatly restrained photoinduced holes transferring to the surface and retarded surface water oxidation reaction, leading to decreased PEC water splitting activity. This study clearly demonstrated that doping could be effective to enhance the PEC activity of α-Fe2O3 nanorods as photoanodes, while it is of great necessity to balance the trade-off between the electronic structure and nanostructure evolution by optimizing the dopant concentration, for increased donor density and meanwhile with the nanorod nanostructure well preserved for directed charge transfer. PMID:26763113

  14. IMC Growth at the Interface of Sn-2.0Ag-2.5Zn Solder Joints with Cu, Ni, and Ni-W Substrates

    NASA Astrophysics Data System (ADS)

    Liang, Jiaxing; Wang, Haozhe; Hu, Anmin; Li, Ming

    2014-11-01

    Growth of intermetallic compounds (IMC) at the interface of Sn-2.0Ag-2.5Zn solder joints with Cu, Ni, and Ni-W substrates have been investigated. For the Cu substrate, a Cu5Zn8 IMC layer with Ag3Sn particles on top was observed at the interface; this acted as a barrier layer preventing further growth of Cu-Sn IMC. For the Ni substrate, a thin Ni3Sn4 film was observed between the solder and the Ni layer; the thickness of the film increased slowly and steadily with aging. For the Ni-W substrate, a thin Ni3Sn4 film was observed between the solder and Ni-W layer. During the aging process a thin layer of the Ni-W substrate was transformed into a bright layer, and the thickness of bright layer increased with aging.

  15. Effects of variations in precursor concentration on the growth of rutile TiO2 nanorods on Si substrate with fabricated fast-response metal-semiconductor-metal UV detector

    NASA Astrophysics Data System (ADS)

    Selman, Abbas M.; Hassan, Z.

    2015-06-01

    This study aimed to investigate the effects of variations in precursor concentration (TiCl3 solution) on the structural, morphological, and optical properties of rutile titanium dioxide (TiO2) nanorods and fabricated metal-semiconductor-metal UV detector depending on the optimal sample. The nanorods were prepared from an aqueous solution of titanium (III) chloride (TiCl3) on p-type, (1 1 1)-oriented Si substrates at different concentrations of TiCl3 solutions (2, 3, 4, and 5 mM). The experimental results showed that the TiO2 nanorods grown at 4 mM concentration exhibited optimal structural properties. A fast-response metal-semiconductor-metal UV detector was fabricated by depositing Pt contacts on the front of the optimal sample via RF reactive magnetron sputtering. Upon exposure to 365 nm light (2.3 mW/cm2) at 5 V bias voltage, the device showed 44.4 sensitivity. In addition, the internal gain was 1.45, and the photoresponse peak was 70 mA/W. The response and the recovery times were calculated to be 7.8 ms upon illumination to a pulse UV light (365 nm) at 5 V bias voltage.

  16. Sea-urchin-like Fe3O4@C@Ag particles: an efficient SERS substrate for detection of organic pollutants

    NASA Astrophysics Data System (ADS)

    Ye, Yingjie; Chen, Jin; Ding, Qianqian; Lin, Dongyue; Dong, Ronglu; Yang, Liangbao; Liu, Jinhuai

    2013-06-01

    Ag-coated sea-urchin-like Fe3O4@C core-shell particles can be synthesized by a facile one-step solvothermal method, followed by deposition of high-density Ag nanoparticles onto the carbon surface through an in situ growth process, respectively. The as-synthesized Ag-coated Fe3O4@C particles can be used as a surface-enhanced Raman scattering (SERS) substrate holding reproducible properties under an external magnetic force. The magnetic function of the particles allows concentrating the composite particles into small spatial regions, which can be exploited to decrease the amount of material per analysis while improving its SERS detection limit. In contrast to the traditional SERS substrates, the present Fe3O4@C@Ag particles hold the advantages of enrichment of organic pollutants for improving SERS detection limit and recycled utilization.Ag-coated sea-urchin-like Fe3O4@C core-shell particles can be synthesized by a facile one-step solvothermal method, followed by deposition of high-density Ag nanoparticles onto the carbon surface through an in situ growth process, respectively. The as-synthesized Ag-coated Fe3O4@C particles can be used as a surface-enhanced Raman scattering (SERS) substrate holding reproducible properties under an external magnetic force. The magnetic function of the particles allows concentrating the composite particles into small spatial regions, which can be exploited to decrease the amount of material per analysis while improving its SERS detection limit. In contrast to the traditional SERS substrates, the present Fe3O4@C@Ag particles hold the advantages of enrichment of organic pollutants for improving SERS detection limit and recycled utilization. Electronic supplementary information (ESI) available: Additional XRD patterns and SEM images of Fe3O4@C particles, SERS spectra of 4-ATP and 4-MPY using Fe3O4@C@Ag particles as the active substrates, magnetic behaviour of Fe3O4@C and Fe3O4@C@Ag particles. See DOI: 10.1039/c3nr01273e

  17. Electrochemical depositions of fluorohydroxyapatite doped by Cu2+, Zn2+, Ag+ on stainless steel substrates

    NASA Astrophysics Data System (ADS)

    Bir, F.; Khireddine, H.; Touati, A.; Sidane, D.; Yala, S.; Oudadesse, H.

    2012-07-01

    Fluoridated hydroxyapatite (FHA, Ca10(PO4)6(OH)2-xFx where 0 < x < 2 is the degree of fluoridation) and inorganic ions (Zn2+, Cu2+, Ag+) substituted fluoridated hydroxyapatite coatings (M-FHA) were deposited on the surface of medical grade 316L stainless steel samples by electrochemical deposition technique. The FHA coatings were co-substituted with antibacterial ions (Zn2+, Cu2+ or Ag+) by co-precipitation and ion-exchange methods. Characterization studies of coatings from X-ray diffraction (XRD), Scanning electron microscopy (SEM) and Energy dispersive X-ray spectroscopy (EDX) showed that the obtained layers are monophase crystals FHA and did not contain any discernible crystalline impurity. The particles of all samples are of nano size that gives thin layers. The surface morphology, microstructure and Ca/P atomic ratio of the FHA coatings can be regulated by varying electrolyte temperature. This later affects the porosity of the coating surface and the chemical compositions of the deposits. Quantitative elemental analysis indicates that the copper, zinc and silver ions are incorporated into the Fluorohydroxyapatite. The antimicrobial effects of doped fluorohydroxyapatite coatings against pathogen bacterial strains Staphylococcus aureus were tested in liquid media. The results are promising and demonstrated that all doped FHA samples exhibit excellent antimicrobial activity "in vitro" against the microorganism, so the antimicrobial properties of the coatings developed are improved.

  18. Resistive switching characteristics of a compact ZnO nanorod array grown directly on an Al-doped ZnO substrate

    NASA Astrophysics Data System (ADS)

    Yoo, E. J.; Shin, J. Y.; Yoon, T. S.; Kang, C. J.; Choi, Y. J.

    2016-07-01

    ZnO’s resistive switching properties have drawn much attention because ZnO has a simple chemical composition and is easy to manipulate. The propulsion mechanism for resistive switching in ZnO is based on a conducting filament that consists of oxygen vacancies. In the case of film structure, the random formation of the conducting filaments occasionally leads to unstable switching characteristics. Limiting the direction in which the conducting filaments are formed is one way to solve this problem. In this study, we demonstrate reliable resistive switching behavior in a device with an Au/compact ZnO nanorod array/Al-doped ZnO structure with stable resistive switching over 105 cycles and a long retention time of 104 s by confining conducting filaments along the boundaries between ZnO nanorods. The restrictive formation of conducting filaments along the boundaries between ZnO nanorods is observed directly using conductive atomic force microscopy.

  19. Polymer-templated electrodeposition of Ag nanosheets assemblies array as reproducible surface-enhanced Raman scattering substrate.

    PubMed

    Liu, Sisi; Xu, Zhimou; Sun, Tangyou; Zhao, Wenning; Wu, Xinghui; Ma, Zhichao; Zhang, Xueming; He, Jian; Chen, Cunhua

    2014-06-01

    Position-configurable, reproducible, vertically aligned nanosheets assemblies (ANAs) arrays are fabricated by polymer-templated electrodeposition method at room temperature. Here, nanoimprint lithography is utilized to fabricate polymer template on the fluorine-doped tin oxide substrate for the purpose of evenly tuning the location of Ag nanostructures. Subsequently, vertically aligned ANAs can be achieved at the bottom of each hole via electrodeposition in a mixed aqueous solution of AgNO3 and citric acid. To obtain uniform ANAs array, we have systematically investigated the factors that influenced the electrodeposition. It was found that the formation of uniform ANAs arrays is strongly depended on the seeding layer, citric acid concentration, electrodeposition potential and time. The as-synthesized ANAs array exhibited a remarkable SERS activity and Raman signal reproducibility to rhodamine 6G, a concentration down to 10(-13) M can be identified. Our results revealed that the ANAs array is a highly desirable candidate as the reliable enhancer for high performance SERS analysis. PMID:24738437

  20. Surface-enhanced Raman scattering (SERS) activity of Ag, Au and Cu nanoclusters on TiO 2-nanotubes/Ti substrate

    NASA Astrophysics Data System (ADS)

    Roguska, Agata; Kudelski, Andrzej; Pisarek, Marcin; Opara, Magdalena; Janik-Czachor, Maria

    2011-07-01

    Tubular arrays of TiO 2 nanotubes (ranging in diameter from 40 to 110 nm) on a Ti substrate were used as a support for Ag, Au or Cu deposits obtained by the sputter deposition technique, where the amount of metal varied from 0.01 to 0.2 mg/cm 2. Those composite supports were intended for surface-enhanced Raman scattering (SERS) investigations. Composite samples were studied with the aid of scanning electron microscopy (SEM) and Auger electron spectroscopy (AES) to reveal their characteristic morphological and chemical features. Raman spectra of pyridine (as a probe molecule) were measured at different cathodic potentials ranging from -0.2 down to -1.2 V after the pyridine had been adsorbed on the metal-covered TiO 2 nanotube/Ti substrates. In addition, SERS spectra on a bulk standard activated Ag, Au and Cu substrates were also measured. The SERS activity of the composite samples was strongly dependent on the amount of metal deposit, e.g. at and above 0.06 mg Ag/cm 2, the intensity of SERS signal was even higher than that for the Ag reference substrate. The high activity of these composites is mainly a result of their specific morphology. The high SERS sensitivity on the surface morphology of the substrate made it possible to monitor very small temporal changes in the Ag metal clusters. This rearrangement was not detectable with microscopic (SEM) or microanalytical (AES) methods. The SERS activity of Au or Cu clusters was distinctly lower than those of Ag. The spectral differences exhibited by the three kinds of composites as compared to the reference metal samples are discussed.

  1. Highly sensitive surface enhanced Raman scattering substrates based on Ag decorated Si nanocone arrays and their application in trace dimethyl phthalate detection

    NASA Astrophysics Data System (ADS)

    Zuo, Zewen; Zhu, Kai; Ning, Lixin; Cui, Guanglei; Qu, Jun; Cheng, Ying; Wang, Junzhuan; Shi, Yi; Xu, Dongsheng; Xin, Yu

    2015-01-01

    Wafer-scale three-dimensional (3D) surface enhancement Raman scattering (SERS) substrates were prepared using the plasma etching and ion sputtering methods that are completely compatible with well-established silicon device technologies. The substrates are highly sensitive with excellent uniformity and reproducibility, exhibiting an enhancement factor up to 1012 with a very low relative standard deviation (RSD) around 5%. These are attributed mainly to the uniform-distributed, multiple-type high-density hot spots originating from the structural characteristics of Ag nanoparticles (NPs) decorated Si nanocone (NC) arrays. We demonstrate that the trace dimethyl phthalate (DMP) at a concentration of 10-7 M can be well detected using this SERS substrate, showing that the AgNPs-decorated SiNC arrays can serve as efficient SERS substrates for phthalate acid esters (PAEs) detection with high sensitivity.

  2. Silver Nanorods Wrapped with Ultrathin Al2O3 Layers Exhibiting Excellent SERS Sensitivity and Outstanding SERS Stability

    PubMed Central

    Ma, Lingwei; Huang, Yu; Hou, Mengjing; Xie, Zheng; Zhang, Zhengjun

    2015-01-01

    Silver nanostructures have been considered as promising substrates for surface-enhanced Raman scattering (SERS) with extremely high sensitivity. The applications, however, are hindered by the facts that their morphology can be easily destroyed due to the low melting points (~100 °C) and their surfaces are readily oxidized/sulfured in air, thus losing the SERS activity. It was found that wrapping Ag nanorods with an ultrathin (~1.5 nm) but dense and amorphous Al2O3 layer by low-temperature atomic layer deposition (ALD) could make the nanorods robust in morphology up to 400 °C, and passivate completely their surfaces to stabilize the SERS activity in air, without decreasing much the SERS sensitivity. This simple strategy holds great potentials to generate highly robust and stable SERS substrates for real applications. PMID:26264281

  3. Electrochemically grown ZnO nanorods for hybrid solar cell applications

    SciTech Connect

    Hames, Yakup; Alpaslan, Zuehal; Koesemen, Arif; San, Sait Eren; Yerli, Yusuf

    2010-03-15

    A hybrid solar cell is designed and proposed as a feasible and reasonable alternative, according to acquired efficiency with the employment of zinc oxide (ZnO) nanorods and ZnO thin films at the same time. Both of these ZnO structures were grown electrochemically and poly(3-hexylthiophene):phenyl-C61-butyric acid methyl ester; (P3HT:PCBM) was used as an active polymer blend, which was found to be compatible to prepared indium-tin-oxide (ITO) substrate base. This ITO base was introduced with mentioned ZnO structure in such a way that, the most efficient configuration was optimized to be ITO/ZnO film/ZnO nanorod/P3HT: PCBM/Ag. Efficiency of this optimized device is found to be 2.44%. All ZnO works were carried out electrochemically, that is indeed for the first time and at relatively lower temperatures. (author)

  4. Flexible indium zinc oxide/Ag/indium zinc oxide multilayer electrode grown on polyethersulfone substrate by cost-efficient roll-to-roll sputtering for flexible organic photovoltaics

    SciTech Connect

    Park, Yong-Seok; Kim, Han-Ki

    2010-01-15

    The authors describe the preparation and characteristics of flexible indium zinc oxide (IZO)-Ag-IZO multilayer electrodes grown on flexible polyethersulfone (PES) substrates using a roll-to-roll sputtering system for use in flexible organic photovoltaics. By the continuous roll-to-roll sputtering of the bottom IZO, Ag, and top IZO layers at room temperature, they were able to fabricate a high quality IZO-Ag-IZO multilayer electrode with a sheet resistance of 6.15 {epsilon}/square, optical transmittance of 87.4%, and figure of merit value of 42.03x10{sup -3} {Omega}{sup -1} on the PES substrate. In addition, the IZO-Ag-IZO multilayer electrode exhibited superior flexibility to the roll-to-roll sputter grown single ITO electrode due to the existence of a ductile Ag layer between the IZO layers and stable amorphous structure of the IZO film. Furthermore, the flexible organic solar cells (OSCs) fabricated on the roll-to-roll sputter grown IZO-Ag-IZO electrode showed higher power efficiency (3.51%) than the OSCs fabricated on the roll-to-roll sputter grown single ITO electrode (2.67%).

  5. A novel surface-enhanced Raman spectroscopy substrate based on a large area of MoS2 and Ag nanoparticles hybrid system

    NASA Astrophysics Data System (ADS)

    Chen, P. X.; Qiu, H. W.; Xu, S. C.; Liu, X. Y.; Li, Z.; Hu, L. T.; Li, C. H.; Guo, J.; Jiang, S. Z.; Huo, Y. Y.

    2016-07-01

    Few layers MoS2 were directly synthesized on Ag nanoparticles (AgNPs) by thermal decomposion method to fabricate a MoS2/AgNPs hybrid system for surface-enhanced Raman scattering (SERS). The MoS2/AgNPs hybrid system shows high performance in terms of sensitivity, signal-to-noise ratio, reproducibility and stability. The minimum detected concentration from MoS2/AgNPs hybrid system for R6 G can reach 10-9 M, which is one order of magnitude lower than that from AgNPs system. The hybrid system shows the reasonable linear response between the Raman intensity and concentration that R2 is reached to 0.988. The maximum deviations of SERS intensities from 20 positions of the SERS substrate are less than 13%. Besides, the hybrid system has a good stability, the Raman intensity only drop by 20% in a month. This work can provide a basis for the fabrication of novel SERS substrates.

  6. Structural and optical properties of Ag-doped copper oxide thin films on polyethylene napthalate substrate prepared by low temperature microwave annealing

    SciTech Connect

    Das, Sayantan; Alford, T. L.

    2013-06-28

    Silver doped cupric oxide thin films are prepared on polyethylene naphthalate (flexible polymer) substrates. Thin films Ag-doped CuO are deposited on the substrate by co-sputtering followed by microwave assisted oxidation of the metal films. The low temperature tolerance of the polymer substrates led to the search for innovative low temperature processing techniques. Cupric oxide is a p-type semiconductor with an indirect band gap and is used as selective absorption layer solar cells. X-ray diffraction identifies the CuO phases. Rutherford backscattering spectrometry measurements confirm the stoichiometry of each copper oxide formed. The surface morphology is determined by atomic force microscopy. The microstructural properties such as crystallite size and the microstrain for (-111) and (111) planes are calculated and discussed. Incorporation of Ag led to the lowering of band gap in CuO. Consequently, it is determined that Ag addition has a strong effect on the structural, morphological, surface, and optical properties of CuO grown on flexible substrates by microwave annealing. Tauc's plot is used to determine the optical band gap of CuO and Ag doped CuO films. The values of the indirect and direct band gap for CuO are found to be 2.02 eV and 3.19 eV, respectively.

  7. Microwave-assisted green synthesis of Ag/reduced graphene oxide nanocomposite as a surface-enhanced Raman scattering substrate with high uniformity

    NASA Astrophysics Data System (ADS)

    Hsu, Kai-Chih; Chen, Dong-Hwang

    2014-04-01

    A nanocomposite of silver nanoparticles/reduced graphene oxide (Ag/rGO) has been fabricated as a surface-enhanced Raman scattering (SERS) substrate owing to the large surface area and two-dimensional nanosheet structure of rGO. A facile and rapid microwave-assisted green route has been used for the formation of Ag nanoparticles and the reduction of graphene oxide simultaneously with L-arginine as the reducing agent. By increasing the cycle number of microwave irradiation from 1 and 4 to 8, the mean diameters of Ag nanoparticles deposited on the surface of rGO increased from 10.3 ± 4.6 and 21.4 ± 10.5 to 41.1 ± 12.6 nm. The SERS performance of Ag/rGO nanocomposite was examined using the common Raman reporter molecule 4-aminothiophenol (4-ATP). It was found that the Raman intensity of 4-ATP could be significantly enhanced by increasing the size and content of silver nanoparticles deposited on rGO. Although the Raman intensities of D-band and G-band of rGO were also enhanced simultaneously by the deposited Ag nanoparticles which limited the further improvement of SERS detection sensitivity, the detectable concentration of 4-ATP with Ag/rGO nanocomposite as the SERS substrate still could be lowered to be 10-10 M and the enhancement factor could be increased to 1.27 × 1010. Furthermore, it was also achievable to lower the relative standard deviation (RSD) values of the Raman intensities to below 5%. This revealed that the Ag/rGO nanocomposite obtained in this work could be used as a SERS substrate with high sensitivity and homogeneity.

  8. Structural and optical properties of dense vertically aligned ZnO nanorods grown onto silver and gold thin films by galvanic effect with iron contamination

    SciTech Connect

    Scarpellini, D.; Paoloni, S.; Medaglia, P.G.; Pizzoferrato, R.; Orsini, A.; Falconi, C.

    2015-05-15

    Highlights: • ZnO nanorods were grown on Au and Ag films in aqueous solution by galvanic effect. • The method is prone to metal contamination which can influence the ZnO properties. • Iron doping improves the lattice matching between ZnO and the substrate. • Energy levels of point defects are lowered and the light emission is red-shifted. • Galvanic-induced nucleation starts and proceeds continuously during the growth. - Abstract: Dense arrays of vertically aligned ZnO nanorods have been grown onto either silver or gold seedless substrates trough a simple hydrothermal method by exploiting the galvanic effect between the substrate and metallic parts. The nanorods exhibit larger bases and more defined hexagonal shapes, in comparison with standard non-galvanic wet-chemistry synthesis. X-ray diffraction (XRD) shows that the iron contamination, associated with the galvanic contact, significantly improves the in-plane compatibility of ZnO with the Au and Ag cubic lattice. Photoluminescence (PL) measurements indicate that the contamination does not affect the number density of localized defects, but lowers their energy levels uniformly; differently, the band-edge emission is not altered appreciably. Finally, we have found that the ZnO hetero-nucleation by galvanic effect initiates at different times in different sites of the substrate area. Our results can be useful for the fabrication of high performance piezonanodevices comprising high-density metal-to-ZnO nanoscaled junctions without intermediate polycrystalline layers.

  9. Superconducting YBCO thin film on multicrystalline Ag film evaporated on MgO substrate

    NASA Astrophysics Data System (ADS)

    Azoulay, Jacob; Verdyan, Armen; Lapsker, Igor

    Superconducting YBa 2Cu 3O 7-δ films were grown by resistive evaporation on multicrystalline silver film which was evaporated on MgO substrate. A simple inexpensive vacuum system equipped with resistively heated boat was used for the whole process. Silver film was first evaporated on MgO substrate kept at 400°C during the evaporation after which with no further annealing a precursor mixture of yttrium small grains and Cu and BaF2 in powder form weighed in the atomic proportion to yield stoichiometric YBa 2Cu 3O 7 was evaporated. The films thus obtained were annealed at 740°C under low oxygen partial pressure of about 1Pa for 30 minutes to form the superconducting phase. X-ray diffraction and scanning electron microscopy techniques were used for texture and surface analysis. Electrical properties were determined using a standard dc four-probe for electrical measurements. The physical and electrical properties of the YBCO films are discussed in light of the fact that X-ray diffraction measurements done on the silver film have revealed a multicrystalline structure

  10. Plasmon-induced broadband fluorescence enhancement on Al-Ag bimetallic substrates

    PubMed Central

    Hao, Qi; Du, Deyang; Wang, Chenxi; Li, Wan; Huang, Hao; Li, Jiaqi; Qiu, Teng; Chu, Paul K.

    2014-01-01

    Surface enhanced fluorescence (SEF) utilizes the local electromagnetic environment to enhance fluorescence from the analyte on the surface of a solid substrate with nanostructures. While the detection sensitivity of SEF is improved with the development of nano-techniques, detection of multiple analytes by SEF is still a challenge due to the compromise between the high enhancing efficiency and broad response bandwidth. In this article, a high-efficiency SEF substrate with broad response bandwidth is obtained by embedding silver in an aluminum film to produce additional bonding and anti-bonding hybridized states. The bimetallic film is fabricated by ion implantation and the ion energy and fluence are tailored to control subsurface location of the fabricated bimetallic nanostructures. The process circumvents the inherent limit of aluminum materials and extends the plasmon band of aluminum from deep UV to visible range. Fluorescence from different dyes excited by 310 nm to 555 nm is enhanced by up to 11 folds on the single bimetallic film and the result is theoretically confirmed by finite-difference time-domain simulations. This work demonstrates that bimetallic film can be used for optical detection of multiple analytes. PMID:25109261

  11. Plasmon-induced broadband fluorescence enhancement on Al-Ag bimetallic substrates.

    PubMed

    Hao, Qi; Du, Deyang; Wang, Chenxi; Li, Wan; Huang, Hao; Li, Jiaqi; Qiu, Teng; Chu, Paul K

    2014-01-01

    Surface enhanced fluorescence (SEF) utilizes the local electromagnetic environment to enhance fluorescence from the analyte on the surface of a solid substrate with nanostructures. While the detection sensitivity of SEF is improved with the development of nano-techniques, detection of multiple analytes by SEF is still a challenge due to the compromise between the high enhancing efficiency and broad response bandwidth. In this article, a high-efficiency SEF substrate with broad response bandwidth is obtained by embedding silver in an aluminum film to produce additional bonding and anti-bonding hybridized states. The bimetallic film is fabricated by ion implantation and the ion energy and fluence are tailored to control subsurface location of the fabricated bimetallic nanostructures. The process circumvents the inherent limit of aluminum materials and extends the plasmon band of aluminum from deep UV to visible range. Fluorescence from different dyes excited by 310 nm to 555 nm is enhanced by up to 11 folds on the single bimetallic film and the result is theoretically confirmed by finite-difference time-domain simulations. This work demonstrates that bimetallic film can be used for optical detection of multiple analytes. PMID:25109261

  12. Plasmon-induced broadband fluorescence enhancement on Al-Ag bimetallic substrates

    NASA Astrophysics Data System (ADS)

    Hao, Qi; Du, Deyang; Wang, Chenxi; Li, Wan; Huang, Hao; Li, Jiaqi; Qiu, Teng; Chu, Paul K.

    2014-08-01

    Surface enhanced fluorescence (SEF) utilizes the local electromagnetic environment to enhance fluorescence from the analyte on the surface of a solid substrate with nanostructures. While the detection sensitivity of SEF is improved with the development of nano-techniques, detection of multiple analytes by SEF is still a challenge due to the compromise between the high enhancing efficiency and broad response bandwidth. In this article, a high-efficiency SEF substrate with broad response bandwidth is obtained by embedding silver in an aluminum film to produce additional bonding and anti-bonding hybridized states. The bimetallic film is fabricated by ion implantation and the ion energy and fluence are tailored to control subsurface location of the fabricated bimetallic nanostructures. The process circumvents the inherent limit of aluminum materials and extends the plasmon band of aluminum from deep UV to visible range. Fluorescence from different dyes excited by 310 nm to 555 nm is enhanced by up to 11 folds on the single bimetallic film and the result is theoretically confirmed by finite-difference time-domain simulations. This work demonstrates that bimetallic film can be used for optical detection of multiple analytes.

  13. Transparent, flexible surface enhanced Raman scattering substrates based on Ag-coated structured PET (polyethylene terephthalate) for in-situ detection

    NASA Astrophysics Data System (ADS)

    Zuo, Zewen; Zhu, Kai; Gu, Chuan; Wen, Yibing; Cui, Guanglei; Qu, Jun

    2016-08-01

    Transparent, flexible surface-enhanced Raman scattering (SERS) substrates were fabricated by metalization of structured polyethylene terephthalate (PET) sheets. The resultant Ag-coated structured PET SERS substrates were revealed to be highly sensitive with good reproducibility and stability, an enhancement factor of 3 × 106 was acquired, which can be attributed mainly to the presence of plentiful multiple-type hot spots within the quasi-three-dimensional surface of the structured PET obtained by oxygen plasma etching. In addition, detections of model molecules on fruit skin were also carried out, demonstrating the great potential of the Ag-coated structured PET in in-situ detection of analyte on irregular objects. Importantly, the technique used for the preparation of such substrate is completely compatible with well-established silicon device technologies, and large-area fabrication with low cost can be readily realized.

  14. Methods of making functionalized nanorods

    DOEpatents

    Gur, Ilan; Milliron, Delia; Alivisatos, A. Paul; Liu, Haitao

    2012-01-10

    A process for forming functionalized nanorods. The process includes providing a substrate, modifying the substrate by depositing a self-assembled monolayer of a bi-functional molecule on the substrate, wherein the monolayer is chosen such that one side of the bi-functional molecule binds to the substrate surface and the other side shows an independent affinity for binding to a nanocrystal surface, so as to form a modified substrate. The process further includes contacting the modified substrate with a solution containing nanocrystal colloids, forming a bound monolayer of nanocrystals on the substrate surface, depositing a polymer layer over the monolayer of nanocrystals to partially cover the monolayer of nanocrystals, so as to leave a layer of exposed nanocrystals, functionalizing the exposed nanocrystals, to form functionalized nanocrystals, and then releasing the functionalized nanocrystals from the substrate.

  15. Transparent SiON/Ag/SiON multilayer passivation grown on a flexible polyethersulfone substrate using a continuous roll-to-roll sputtering system

    PubMed Central

    2012-01-01

    We have investigated the characteristics of a silicon oxynitride/silver/silicon oxynitride [SiON/Ag/SiON] multilayer passivation grown using a specially designed roll-to-roll [R2R] sputtering system on a flexible polyethersulfone substrate. Optical, structural, and surface properties of the R2R grown SiON/Ag/SiON multilayer were investigated as a function of the SiON thickness at a constant Ag thickness of 12 nm. The flexible SiON/Ag/SiON multilayer has a high optical transmittance of 87.7% at optimized conditions due to the antireflection and surface plasmon effects in the oxide-metal-oxide structure. The water vapor transmission rate of the SiON/Ag/SiON multilayer is 0.031 g/m2 day at an optimized SiON thickness of 110 nm. This indicates that R2R grown SiON/Ag/SiON is a promising thin-film passivation for flexible organic light-emitting diodes and flexible organic photovoltaics due to its simple and low-temperature process. PMID:22221400

  16. Electric Field Assisted Assembly of Perpendicular Oriented NanorodSuperlattices

    SciTech Connect

    Ryan, Kevin M.; Mastroianni, Alex; Stancil, Kimani A.; Liu,Haitao; Alivisatos, Paul A.

    2006-04-10

    We observe the assembly of CdS nanorod superlattices by thecombination of a DC electric field and solvent evaporation. In eachelectric field (1 V/um) assisted assembly, CdS nanorods (5 x 30 nm)suspended initially in toluene were observed to align perpendicularly tothe substrate. Azimuthal alignment along the nanorod crystal faces andthe presence of stacking faults indicate that both 2D and 3D assemblieswere formed by a process of controlled super crystal growth.

  17. Influence of a hot and humid environment on thermal transport across the interface between a Ag thin-film line and a substrate

    NASA Astrophysics Data System (ADS)

    Li, Yuan; Noguchi, Kyohei; Saka, Masumi

    2016-04-01

    To evaluate the reliability of Ag thin-film lines for a wide range of applications in electronic devices, knowledge of the thermal transport across the interface between the line and the underlying substrate is of great importance. This is because such thermal transport significantly affects the temperature distribution in the line, the electrical performance of the line and the service life of the device the line is installed on. In this work, we examine the influence of a hot and humid environment on the thermal transport across the interface between a Ag thin-film line and a substrate. By performing a series of current-stressing experiments using the four-point probe method at atmospheric conditions (296 K and 30 RH%) on a Ag thin-film line for different durations of exposure to a hot and humid environment (323 K and 90 RH%), the electrical resistivity was found to increase with the exposure duration. Such an increase is believed to be the result of a decrease in the interfacial thermal conductance, which indicates less thermal transport from the line to the substrate. Moreover, by observing the surface morphology changes in the line and conducting a one-dimensional electro-thermal analysis, such variations can be attributed to the generation and growth of voids within the line, which hinder heat transfer from the line to the substrate through the interface.

  18. Ordered array of Ag semishells on different diameter monolayer polystyrene colloidal crystals: An ultrasensitive and reproducible SERS substrate

    PubMed Central

    Yi, Zao; Niu, Gao; Luo, Jiangshan; Kang, Xiaoli; Yao, Weitang; Zhang, Weibin; Yi, Yougen; Yi, Yong; Ye, Xin; Duan, Tao; Tang, Yongjian

    2016-01-01

    Ag semishells (AgSS) ordered arrays for surface-enhanced Raman scattering (SERS) spectroscopy have been prepared by depositing Ag film onto polystyrene colloidal particle (PSCP) monolayer templates array. The diversified activity for SERS activity with the ordered AgSS arrays mainly depends on the PSCP diameter and Ag film thickness. The high SERS sensitivity and reproducibility are proved by the detection of rhodamine 6G (R6G) and 4-aminothiophenol (4-ATP) molecules. The prominent enhancements of SERS are mainly from the “V”-shaped or “U”-shaped nanogaps on AgSS, which are experimentally and theoretically investigated. The higher SERS activity, stability and reproducibility make the ordered AgSS a promising choice for practical SERS low concentration detection applications. PMID:27586562

  19. Ordered array of Ag semishells on different diameter monolayer polystyrene colloidal crystals: An ultrasensitive and reproducible SERS substrate.

    PubMed

    Yi, Zao; Niu, Gao; Luo, Jiangshan; Kang, Xiaoli; Yao, Weitang; Zhang, Weibin; Yi, Yougen; Yi, Yong; Ye, Xin; Duan, Tao; Tang, Yongjian

    2016-01-01

    Ag semishells (AgSS) ordered arrays for surface-enhanced Raman scattering (SERS) spectroscopy have been prepared by depositing Ag film onto polystyrene colloidal particle (PSCP) monolayer templates array. The diversified activity for SERS activity with the ordered AgSS arrays mainly depends on the PSCP diameter and Ag film thickness. The high SERS sensitivity and reproducibility are proved by the detection of rhodamine 6G (R6G) and 4-aminothiophenol (4-ATP) molecules. The prominent enhancements of SERS are mainly from the "V"-shaped or "U"-shaped nanogaps on AgSS, which are experimentally and theoretically investigated. The higher SERS activity, stability and reproducibility make the ordered AgSS a promising choice for practical SERS low concentration detection applications. PMID:27586562

  20. Noble metal nanodisks epitaxially formed on ZnO nanorods and their effect on photoluminescence

    NASA Astrophysics Data System (ADS)

    Chu, Sheng; Ren, Jingjian; Yan, Dong; Huang, Jian; Liu, Jianlin

    2012-07-01

    Triangular and hexagonal shaped noble metal (Au, Ag, Pt, Pd) nanodisks were synthesized on the top facets of ZnO nanorods via simple deposition-annealing method. Other metals (Ni, Cu, Cr, Pb, Al) only formed irregular shaped nanostructures on ZnO nanorods. The morphology, elemental composition, as well as growth mechanism of the metal nanodisks/ZnO nanorod composite materials were studied. The localized surface plasmon resonant effects from different metal nanodisks on the photoluminescence of ZnO nanorods were investigated. It was demonstrated that the carriers transfer between the metal nanodisks and ZnO can efficiently manipulate the photoluminescence intensities from the nanorods.

  1. Rich variety of substrates for surface enhanced Raman spectroscopy

    NASA Astrophysics Data System (ADS)

    Nguyen, Bich Ha; Hieu Nguyen, Van; Nhung Tran, Hong

    2016-09-01

    The efficiency of the application of surface enhanced Raman spectroscopy (SERS) technique to each specified purpose significantly depends on the choice of the SERS substrate with an appropriate structure as well as on its performance. Until the present time a rich variety of SERS substrates was fabricated. They can be classified according to their structures. The present work is a review of main types of SERS substrates for using in the trace analysis application. They can be classified into 4 groups: (1) Substrates using gold nanoparticles (AuNPs) with spherical shape such as colloidal AuNPs, AuNPs fabricated by pulsed laser deposition, by sputtering or by capillary force assembly (CFA), substrates fabricated by electrospinning technique, substrates using metallic nanoparticle arrays fabricated by electron beam lithography combined with CFA method, substrates using silver nanoparticle (AgNP) arrays grain by chemical seeded method, substrates with tunable surface plasmon resonance, substrates based on precies subnanometer plasmonic junctions within AuNP assemblies, substrates fabricated by simultaneously immobilizing both AuNPs and AgNPs on the same glass sides etc. (2) Substrates using nanostructures with non-spherical shapes such as gold nanowire (NW), or highly anisotropic nickel NW together with large area, free-standing carpets, substrates with obviously angular, quasi-vertically aligned cuboid-shaped TiO2 NW arrays decorated with AgNPs, substrates using gold nanoprism monolayer films, substrates using silver nanocube dimmers or monodisperse close-packed gold nanotriangle monolayers. (3) Substrates using multiparticle complex nanostructure such as nanoparticle cluster arrays, gold nanoflowers and nanodendrites. (4) Flexible substrate such as paper-based swab with gold nanorods, adhesive polymer tapes fabricated by inkjet printing method and flexible and adhesive SERS tapes fabricated by decorating AuNPs via the conventional drop-dry method.

  2. Selective Facet Reactivity During Cation Exchange in Cadmium Sulfide Nanorods

    SciTech Connect

    Sadtler, Bryce; Demchenko, Denis; Zheng, Haimei; Hughes, Steven; Merkle, Maxwell; Dahmen, Ulrich; Wang, Lin-Wang; Alivisatos, A. Paul

    2008-12-18

    The partial transformation of ionic nanocrystals through cation exchange has been used to synthesize nanocrystal heterostructures. We demonstrate that the selectivity for cation exchange to take place at different facets of the nanocrystal plays an important role in determining the resulting morphology of the binary heterostructure. In the case of copper I (Cu+) cation exchange in cadmium sulfide (CdS) nanorods, the reaction starts preferentially at the ends of the nanorods such that copper sulfide (Cu2S) grows inwards from either end. The resulting morphology is very different from the striped pattern obtained in our previous studies of silver I (Ag+) exchange in CdS nanorods where non-selective nucleation of silver sulfide (Ag2S) occurs. From interface formation energies calculated for several models of epitaxialconnections between CdS and Cu2S or Ag2S, we infer the relative stability of each interface during the nucleation and growth of Cu2S or Ag2S within the CdS nanorods. The epitaxial connections of Cu2S to the end facets of CdS nanorods minimize the formation energy, making these interfaces stable throughout the exchange reaction. However, as the two end facets of wurtzite CdS nanorods are crystallographically nonequivalent, asymmetric heterostructures can be produced.

  3. Antifungal activity of Ag:hydroxyapatite thin films synthesized by pulsed laser deposition on Ti and Ti modified by TiO2 nanotubes substrates

    NASA Astrophysics Data System (ADS)

    Eraković, S.; Janković, A.; Ristoscu, C.; Duta, L.; Serban, N.; Visan, A.; Mihailescu, I. N.; Stan, G. E.; Socol, M.; Iordache, O.; Dumitrescu, I.; Luculescu, C. R.; Janaćković, Dj.; Miškovic-Stanković, V.

    2014-02-01

    Hydroxyapatite (HA) is a widely used biomaterial for implant thin films, largely recognized for its excellent capability to chemically bond to hard tissue inducing the osteogenesis without immune response from human tissues. Nowadays, intense research efforts are focused on development of antimicrobial HA doped thin films. In particular, HA doped with Ag (Ag:HA) is expected to inhibit the attachment of microbes and contamination of metallic implant surface. We herewith report on nano-sized HA and Ag:HA thin films synthesized by pulsed laser deposition on pure Ti and Ti modified with 100 nm diameter TiO2 nanotubes (fabricated by anodization of Ti plates) substrates. The HA-based thin films were characterized by SEM, AFM, EDS, FTIR, and XRD. The cytotoxic activity was tested with HEp2 cells against controls. The antifungal efficiency of the deposited layers was tested against the Candida albicans and Aspergillus niger strains. The Ti substrates modified with TiO2 nanotubes covered with Ag:HA thin films showed the highest antifungal activity.

  4. Synthesis and enhanced light absorption of alumina matrix nanocomposites containing multilayer oxide nanorods and silver nanoparticles

    SciTech Connect

    Gan, Yong X.; Zeng, Xianwu; Su, Lusheng; Yang, Lu; Gan, Bo J.; Zhang, Lihua

    2011-11-15

    Highlights: {yields} Multilayer oxide nanorods (nanocables) were obtained via chemical processing. {yields} Ag nanoparticles were deposited between the core and shell layers of the nanorods. {yields} The structure and composition of the nanorods were analyzed by SEM and TEM. {yields} CoO nanorods and Ag nanoparticles enhance light absorption of the nanocomposites. -- Abstract: In this paper, multilayer oxide nanorods were deposited in the nanopores of anodic aluminum oxide (AAO) via solution infiltration followed by heat treatment. The nanorods have a core-shell structure. First, the shell (nanotube) with the thickness of about 40 nm was made of TiO{sub 2} through the hydrolysis of (NH{sub 4}){sub 2}TiF{sub 6}. Second, silver nanoparticles with the diameter of about 3 nm were added into the TiO{sub 2} layer through thermal decomposition of AgNO{sub 3} at elevated temperatures. Then, cylindrical cores (nanorods) of CoO and ZnO with 200 nm diameter were prepared, respectively. Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) were used to characterize the structure and composition of the nanorods. UV-vis light absorption measurements in the wavelength range from 350 to 1000 nm were performed to study the effect of nanorod and nanoparticle addition on the light absorption property of the alumina nanocomposites. It is found that CoO nanorods increase the light absorption of the alumina matrix composite in the wavelength range from 500 nm to 800 nm, but the TiO{sub 2} shell does not increase the light absorption much. The ZnO nanorods do not change the light absorption either. However, the addition of silver nanoparticles significantly enhances light absorption of both AAO/TiO{sub 2}/Ag/CoO and AAO/TiO{sub 2}/Ag/ZnO nanocomposites. This increase in the visible light absorption reveals that there exists surface plasmon around the fine silver nanoparticles in the nanorods.

  5. Microstructure of Co/X (X=Cu,Ag,Au) epitaxial thin films grown on Al{sub 2}O{sub 3}(0001) substrates

    SciTech Connect

    Ohtake, Mitsuru; Akita, Yuta; Futamoto, Masaaki; Kirino, Fumiyoshi

    2007-05-01

    Epitaxial thin films of Co/X (X=Cu,Ag,Au) were prepared on Al{sub 2}O{sub 3}(0001) substrates at substrate temperatures of 100 and 300 degree sign C by UHV molecular beam epitaxy. A complicated microstructure was realized for the epitaxial thin films. In-situ reflection high-energy electron diffraction observation has shown that X atoms of the buffer layer segregated to the surface during Co layer deposition, and it yielded a unique epitaxial granular structure. The structure consists of small Co grains buried in the X buffer layer, where both the magnetic small Co grains and the nonmagnetic X layer are epitaxially grown on the single crystal substrate. The structure varied depending on the X element and the substrate temperature. The crystal structure of Co grains is influenced by the buffer layer material and determined to be hcp and fcc structures for the buffer layer materials of Au and Cu, respectively.

  6. Highly Reproducible and Sensitive SERS Substrates with Ag Inter-Nanoparticle Gaps of 5 nm Fabricated by Ultrathin Aluminum Mask Technique.

    PubMed

    Fu, Qun; Zhan, Zhibing; Dou, Jinxia; Zheng, Xianzheng; Xu, Rui; Wu, Minghong; Lei, Yong

    2015-06-24

    Applicable surface enhanced Raman scattering (SERS) active substrates require high enhancement factor (EF), excellent spatial reproducibility, and low-cost fabrication method on a large area. Although several SERS substrates with high EF and relative standard deviation (RSD) of signal less than 5% were reported, reliable fabrication for large area SERS substrates with both high sensitivity and high reproducibility via low-cost routes remains a challenge. Here, we report a facile and cost-effective fabrication process for large-scale SERS substrate with Ag inter-nanoparticle (NP) gaps of 5 nm based on ultrathin alumina mask (UTAM) surface pattern technique. Such closely packed Ag NP arrays with high density of electromagnetic field enhancement ("hot spots") on large area exhibit high SERS activity and excellent reproducibility, simultaneously. Rhodamine 6G molecules with concentration of 1 × 10(-7) M are used to determine the SERS performance, and an EF of ∼10(9) is obtained. It should be noted that we obtain RSDs about 2% from 10 random spots on an area of 1 cm(2), which implies the highly reproducible signals. Finite-difference time-domain simulations further suggest that the enhanced electric field originates from the narrow gap, which agrees well with the experimental results. The low value of RSD and the high EF of SERS signals indicate that the as-prepared substrate may be promising for highly sensitive and uniform SERS detection. PMID:26023763

  7. 3D Ag/ZnO hybrids for sensitive surface-enhanced Raman scattering detection

    NASA Astrophysics Data System (ADS)

    Huang, Chenyue; Xu, Chunxiang; Lu, Junfeng; Li, Zhaohui; Tian, Zhengshan

    2016-03-01

    To combine the surface plasma resonance of metal and local field enhancement in metal/semiconductor interface, Ag nanoparticles (NPs) were assembled on a ZnO nanorod array which was grown by hydrothermally on carbon fibers. The construction of dimensional (3D) Surface-Enhanced Raman Scattering (SERS) substrate is used for the sensitive detection of organic pollutants with the advantages such as facile synthesis, short detection time and low cost. The hybrid substrate was manifested a high sensitivity to phenol red at a lower concentration of 1 × 10-9 M and a higher enhancement factor of 3.18 × 109. Moreover, the ZnO nanostructures decorated with Ag NPs were demonstrated self-cleaning function under UV irradiation via photocatalytic degradation of the analytic molecules. The fabrication process of the materials and sensors, optimization of the SERS behaviors for different sized Ag NPs, the mechanism of SERS and recovery were presented with a detailed discussion.

  8. Polarization dependent, surface plasmon induced photoconductance in gold nanorod arrays

    NASA Astrophysics Data System (ADS)

    Diefenbach, S.; Erhard, N.; Schopka, J.; Martin, A.; Karnetzky, C.; Iacopino, D.; Holleitner, A. W.

    2014-03-01

    We report on the photoconductance in two-dimensional arrays of gold nanorods which is strongly enhanced at the frequency of the longitudinal surface plasmon of the nanorods. The arrays are formed by a combination of droplet deposition and stamping of gold nanorod solutions on SiO2 substrates. We find that the plasmon induced photoconductance is sensitive to the linear polarization of the exciting photons. We interpret the occurrence of the photoconductance as a bolometric enhancement of the arrays' conductance upon excitation of the longitudinal surface plasmon resonance of the nanorods.

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

    SciTech Connect

    Nour, E. S. Echresh, A.; Willander, M.; Nur, O.; Liu, Xianjie; Broitman, E.

    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 of 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.

  10. Synthesis and optical properties of gold nanorods with controllable morphology.

    PubMed

    Ye, Tianyu; Dai, Zhigao; Mei, Fei; Zhang, Xingang; Zhou, Yuanming; Xu, Jinxia; Wu, Wei; Xiao, Xiangheng; Jiang, Changzhong

    2016-11-01

    Searching for architectural building blocks with tunable morphology and peculiarity is a prominent challenge for novel diagnostic and therapeutic applications. Here, the aqueous-based seed-mediated methods for preparing highly mono-dispersed Au nanorods with a different aspect ratio are systematically studied by controlling the amounts of Ag ions and seeds. We also explore the effect of pH on the synthesis of gold nanorods. The realization of the overlap of longitudinal plasmon band and excitation source with different degrees is made by changing the aspect ratio of nanorod in order to determine its effect on the overall surface enhancement. In addition, the gold octahedra are prepared by overgrowth on Au nanorods. The SERS effects of Au nanorods are researched and the FDTD simulations are performed to reveal the morphology induced plasmon modes. PMID:27602883

  11. Growth of CdS Nanorods and Deposition of Silver Nanoparticles.

    PubMed

    Zhao, Jie; Yang, Fanghong; Yang, Ping

    2015-05-01

    Systematic investigations have been done to deposit silver nanoparticles on seeded CdS nanorods. The CdS nanorods were synthesized by using CdS nanocrystals as seeds being indexed to the cubic structure (zinc-blende) and tetradecylphosphonic acid as surfactants to enable preferential growth on the reactive {001} facets. Ostwald ripening process occurred during the growth of CdS nanorods. Ag/CdS heterostructures were obtained through a facile method in which oleylamine was employed as reducing agents under an elevated temperature. Exposing CdS nanorods to Ag+ ions resulted in Ag domains depositing on the tips of the nanorods or defected sites embedding in the nanorod surfaces. Ag domains formed separate nuclei and grew quickly at a high concentration of AgNO3 solution. We further focused on discussing the morphology formation mechanism and optical properties of the heterostructures and the nanorods. The as-synthesized Ag/CdS heterostructures can facilitate charge separation at the metal-semiconductor interface. Herein, it opens up an application possibility of enhancing photocatalytic processes and other devices. PMID:26505026

  12. Process of in situ forming well-aligned zinc oxide nanorod arrays on wood substrate using a two-step bottom-up method.

    PubMed

    Liu, Yongzhuang; Fu, Yanchun; Yu, Haipeng; Liu, Yixing

    2013-10-01

    A good nanocrystal covering layer on wood can serve as a protective coating and present some new surface properties. In this study, well-aligned ZnO nanorods (NRs) arrays were successfully grown on wood surface through a two-step bottom-up growth process. The process involved pre-sow seeds and subsequently their growing into NRs under hydrothermal environment. The interface incorporation between wood and ZnO colloid particles in the precursor solution during the seeding process was analyzed and demonstrated through a schematic. The growth process of forming well-aligned ZnO NRs was analyzed by field-emission scanning electron microscopy and X-ray diffraction, which showed that the NRs elongated with increased reaction time. The effects of ZnO crystal form and capping agent on the growth process were studied through different viewpoints. PMID:23880522

  13. Characteristic difference between ITO/ZrCu and ITO/Ag bi-layer films as transparent electrodes deposited on PET substrate

    NASA Astrophysics Data System (ADS)

    Lee, C. J.; Lin, H. K.; Sun, S. Y.; Huang, J. C.

    2010-10-01

    The metallic-glass film of ZrCu layer deposited by co-sputtering was utilized as the metallic layer in the bi-layer structure transparent conductive electrode of ITO/ZrCu (IZC) deposited on the PET substrate using magnetron sputtering at room temperature. In addition, the pure Ag metal layer was applied in the same structure of transparent conductive film, ITO/Ag, in comparison with the IZC film. The ZrCu layer could form a continuous and smooth film in thickness lower than 6 nm, compared with the island structure of pure Ag layer of the same thickness. The 30 nm ITO/3 nm ZrCu films could show the optical transmittance of 73% at 550 nm wavelength. The 30 nm ITO/12 nm ZrCu films could show the better sheet resistance of 20 Ω/sq, but it was still worse than that of the ITO/Ag films. It was suggested that an alloy system with lower resistivity and negative mixing heat between atoms might be another way to form a continuous layer in thickness lower than 6 nm for metal film.

  14. Surface area-dependent second harmonic generation from silver nanorods.

    PubMed

    Ngo, Hoang Minh; Luong, Thanh Tuyen; Ledoux-Rak, Isabelle

    2016-08-17

    The nonlinear optical (NLO) properties of metallic nanoparticles strongly depend on their size and shape. Metallic gold nanorods have already been widely investigated, but other noble metals could also be used for nanorod fabrication towards applications in photonics. Here we report on the synthesis and NLO characterization of silver nanorods (AgNRs) with controllable localized surface plasmon resonance. We have implemented an original, one-step and seedless synthesis method, based on a spontaneous particle growth technique in the presence of polyvinylpyrrolidone (PVP) as a capping agent. Colloidal solutions of AgNRs with various aspect ratios (5.0; 6.3; 7.5; 8.2 and 9.7) have been obtained and characterized using Harmonic light scattering (HLS) at 1064 nm, in order to investigate their quadratic NLO properties. From HLS experiments, we demonstrate that hyperpolarizability (β) values of AgNRs display a strong dependence on their surface area. PMID:27498825

  15. Gold Nanobipyramid-Directed Growth of Length-Variable Silver Nanorods with Multipolar Plasmon Resonances.

    PubMed

    Zhuo, Xiaolu; Zhu, Xingzhong; Li, Qian; Yang, Zhi; Wang, Jianfang

    2015-07-28

    We report on a method for the preparation of uniform and length-variable Ag nanorods through anisotropic Ag overgrowth on high-purity Au nanobipyramids. The rod diameters can be roughly tailored from ∼20 nm to ∼50 nm by judicious selection of differently sized Au nanobipyramids. The rod lengths can be tuned from ∼150 nm to ∼550 nm by varying the Ag precursor amount during the overgrowth process and/or by anisotropic shortening through mild oxidation. The controllable aspect ratios, high purity, and high dimensional uniformity of these Ag nanorods enable the observation of Fabry-Pérot-like multipolar plasmon resonance modes in the colloidal suspensions at the ensemble level, which has so far been demonstrated only on Au nanorods prepared electrochemically with anodic aluminum oxide templates. Depending on the mode order and geometry of the Ag nanorods, the multipolar plasmon wavelengths can be readily tailored over a wide spectral range from the visible to near-infrared region. We have further elucidated the relationships between the multipolar plasmon wavelengths and the geometric dimensions of the Ag nanorods at both the ensemble and single-particle levels. Our results indicate that the Au nanobipyramid-directed, dimensionally controllable Ag nanorods will be an attractive and promising candidate for developing multipolar plasmon-based devices and applications. PMID:26135608

  16. Vertical silver nanorod growth as a surface-enhanced Raman scattering

    NASA Astrophysics Data System (ADS)

    Myoung, NoSoung; Park, Jung Su; Shin, Yong-Suk; Lee, Chang-Lyoul; Yim, Sang-Youp

    2015-03-01

    We report an optimization of the fabrication method on arrays of vertically grown nanometer scaled silver rod using nanosphere (polystyrene) lift-off on SiO2 wafer as a surface-enhance Raman scattering substrate by thermal evaporation technology as well as real-time vapor phase detection of CHCl3 by the radiation of fiber optic coupled 785 nm diode laser. Raman peak at 668.2 cm-1 for CHCl3 (C-H stretching band) was compared to the peak at 1088.4 cm-1 of 1- propanethiol (CH3 rock band) and the detection limit of CHCl3 vapor phase contamination level was estimated as a function of the peak intensity ratio of 668.2 vs. 1088.4. The detectable range using Ag nanorod wells on SiO2 substrate was 20-800 ppm. We were able to make significant steps toward developing cost effective nano-pattern as a Raman sensor.

  17. Hydroquinone Based Synthesis of Gold Nanorods.

    PubMed

    Picciolini, Silvia; Mehn, Dora; Ojea-Jiménez, Isaac; Gramatica, Furio; Morasso, Carlo

    2016-01-01

    Gold nanorods are an important kind of nanoparticles characterized by peculiar plasmonic properties. Despite their widespread use in nanotechnology, the synthetic methods for the preparation of gold nanorods are still not fully optimized. In this paper we describe a new, highly efficient, two-step protocol based on the use of hydroquinone as a mild reducing agent. Our approach allows the preparation of nanorods with a good control of size and aspect ratio (AR) simply by varying the amount of hexadecyl trimethylammonium bromide (CTAB) and silver ions (Ag(+)) present in the "growth solution". By using this method, it is possible to markedly reduce the amount of CTAB, an expensive and cytotoxic reagent, necessary to obtain the elongated shape. Gold nanorods with an aspect ratio of about 3 can be obtained in the presence of just 50 mM of CTAB (versus 100 mM used in the standard protocol based on the use of ascorbic acid), while shorter gold nanorods are obtained using a concentration as low as 10 mM. PMID:27585238

  18. Multifunctional nanotube-like Fe3O4/PANI/CDs/Ag hybrids: An efficient SERS substrate and nanocatalyst.

    PubMed

    Yan, Manqing; Shen, Yang; Zhang, Guiyang; Bi, Hong

    2016-01-01

    In this paper, the stable and environment-friendly Fe3O4 nanotubes with polyaniline (Fe3O4 NTs/PANI hybrids) have been prepared via mesoporous anodic alumina oxide (AAO) template, sol-gel method and in-situ polymerization. Then multifunctional Fe3O4 NTs/PANI/Ag hybrids have been obtained by decorating Ag nanoparticles by glucose reduction on surface of Fe3O4 NTs/PANI hybrids. The morphologies and structures of these hybrids were subsequently investigated by SEM, XRD, TEM and XPS measurements. The Fe3O4 NTs/PANI/Ag hybrids presented high catalytic activity due to the template-assisted presence, preventing Ag particulate agglomeration. Importantly, the Fe3O4 NTs/PANI/Ag hybrids achieve sensitive surface-enhanced Raman scattering (SERS) signals. Furthermore, the introduction of carbon dots (CDs) endows these hybrids good dispersion and stable photoluminescence (PL). Therefore, the obtained hybrids may have potential applications in waste water treatment, biomedicine, photocatalyst, and environmental analysis. PMID:26478345

  19. Growth process for gallium nitride porous nanorods

    SciTech Connect

    Wildeson, Isaac Harshman; Sands, Timothy David

    2015-03-24

    A GaN nanorod and formation method. Formation includes providing a substrate having a GaN film, depositing SiN.sub.x on the GaN film, etching a growth opening through the SiN.sub.x and into the GaN film, growing a GaN nanorod through the growth opening, the nanorod having a nanopore running substantially through its centerline. Focused ion beam etching can be used. The growing can be done using organometallic vapor phase epitaxy. The nanopore diameter can be controlled using the growth opening diameter or the growing step duration. The GaN nanorods can be removed from the substrate. The SiN.sub.x layer can be removed after the growing step. A SiO.sub.x template can be formed on the GaN film and the GaN can be grown to cover the SiO.sub.x template before depositing SiN.sub.x on the GaN film. The SiO.sub.x template can be removed after growing the nanorods.

  20. Ag electrode modified with polyhexamethylene biguanide stabilized silver nanoparticles: a new type of SERS substrates for detection of enzymatically generated thiocholine

    NASA Astrophysics Data System (ADS)

    Tepanov, A. A.; Nechaeva, N. L.; Prokopkina, T. A.; Kudrinskiy, A. A.; Kurochkin, I. N.; Lisichkin, G. V.

    2015-11-01

    The detection of thiocholine is one of the most widespread techniques for estimation of the cholinesterase activity - acetylcholinesterase and butyrylcholinesterase. Both cholinesterases can be inhibited by organophosphates and carbamates and accordingly can be considered for estimation of these pollutants in the environment. In the current work, SERS spectroscopy was applied for the thiocholine detection. The Ag electrodes modified with silver nanoparticles stabilized by polyhexamethylene biguanide were for the first time suggested as SERS-substrates for that purpose. Such electrodes can be applicable for SERS detection of submicromolar concentrations of thiocholine.

  1. Tailoring the optical and hydrophobic property of zinc oxide nanorod by coating with amorphous graphene

    NASA Astrophysics Data System (ADS)

    Pahari, D.; Das, N. S.; Das, B.; Chattopadhyay, K. K.; Banerjee, D.

    2016-09-01

    Zinc oxide (ZnO) nanorods were synthesized at room temperature on potassium permanganate activated silicon and glass substrate by simple chemical method using zinc acetate as precursor. To modify the surface energy of the as prepared ZnO thin films the samples were coated with amorphous graphene (a-G) synthesized by un-zipping of chemically synthesized amorphous carbon nanotubes (a-CNTs). All the pure and coated samples were characterized by x-ray diffraction, field emission scanning electron microscope, Raman spectroscopy, and Fourier transformed infrared spectroscopy. The roughness analysis of the as prepared samples was done by atomic force microscopic analysis. The detail optical properties of all the samples were studied with the help of a UV-Visible spectrophotometer. The surface energy of the as prepared pure and coated samples was calculated by measuring the contact angle of two different liquids. It is seen that the water repellence of ZnO nanorods got increased after they are being coated with a-Gs. Also even after UV irradiation the contact angle remain same unlike the case for the uncoated sample where the contact angle gets decreased significantly after UV irradiation. Existing Cassie-Wenzel model has been employed along with the Owen's approach to determine the different components of surface energy.

  2. An approach to self-cleaning SERS sensors by arraying Au nanorods on TiO II layer

    NASA Astrophysics Data System (ADS)

    Li, Shuyi; Suzuki, Motofumi; Nakajima, Kaoru; Kimura, Kenji; Fukuoka, Takao; Mori, Yasushige

    2007-09-01

    We have demonstrated stable surface-enhanced Raman spectroscopy (SERS) on arrays of Au nanorods aligned on a photocatalytic TiO II layer. We used dynamic oblique deposition (DOD) in order to control the morphology of both the Au nanorods and the TiO II layer so that both Au and TiO II appear on the surface and play the roles of Raman enhancer and self-cleaner, respectively. TiO II template layer was formed by depositing Ti IIO 3 onto heated glass substrate in an oxygen atmosphere so that it was ready as photocatalyst when the deposition was over, without post annealing in the air. A serial bideposition technique (SBD) at a deposition angle of 85° was used to control the morphology of TiO II layer suitable for the growth of Au nanorods. Then, Au nanorods were arrayed by depositing Au with different deposition angles and thicknesses on the TiO II layer. We investigated the photocatalysis and SERS properties of the samples and found that they show both good photocatalysis and strong signals of SERS although these properties varies depend on the deposition angle and thickness of Au layer. Most importantly, we found that the SERS signals measured on our samples have shown spatially-, temporally-stable characters which have not been observed before on the Ag or Au nanorods deposited on a SiO II layer. This stability is interpreted in terms of the self-cleaning character due to the photocatalytic TiO2 template layer.

  3. Surface enhanced Raman scattering (SERS) study of L-arginine adsorbed on Ag nanoclusters on glass substrate by nanocluster deposition method

    NASA Astrophysics Data System (ADS)

    Botta, Raju; Bansal, C.

    2015-06-01

    Spheroidal shape Ag nanoclusters were prepared using inert gas phase condensation technique of cluster deposition system. Annealed the Ag nanocluster film at 300 °C to get proper size and also tune the surface plasmon resonance (SPR) with excitation wavelength. L- Arginine (L-Arg) amino acid was taken to study the quantitative nature of the Raman peaks with molar concentration. Wide range of aqueous solution of L-Arg amino acid was prepared by sequential dilution method (1 mM to 1 µM) and 40 µL of L-Arg was dropped on the Ag nanocluster film and allowed to dry in the ambient conditions. Further Raman measurements were carried out using 514 nm laser excitation sources. Guanidium fragment vibrational mode and COO- symmetric stretching mode peaks were taken for the quantitative measurement. All the SERS spectrums are in good agreement with earlier reports and are reproducible over the substrate. A good correlation between peak intensity and molar concentration was found. These results show promising applications in the protein analysis.

  4. Comparison of a Fluorinated Aryl Thiol Self-Assembled Monolayer with Its Hydrogenated Counterpart on Polycrystalline Ag Substrates

    SciTech Connect

    Schalnat, Matthew C.; Pemberton, Jeanne E.

    2010-07-20

    The effects of perfluorination of aryl thiols on surface coverage, surface electronic properties, and molecular orientation of self-assembled monolayers of thiophenol (TP) and pentafluorothiophenol (F5TP) on polycrystalline Ag were evaluated using linear sweep voltammetry, ultraviolet photoelectron spectroscopy (UPS), and surface Raman spectroscopy, respectively. Electrochemical reductive desorption by linear sweep voltammetry indicates a surface coverage for the TP monolayer of (5.07 ± 1.29) × 10-10 mol/cm2, equating to a molecular area of 32.8 ± 8.3 Å2, and a surface coverage for the F5TP monolayer of (1.95 ± 0.59) × 10-10 mol/cm2, equating to an area of 85.2 ± 25.8 Å2/molecule. TP-modified Ag exhibits a change in work function (ΔΦ) of -0.64 eV relative to bare Ag, whereas F5TP-modified Ag exhibits a ΔΦ of +0.54 eV relative to bare Ag. Quantitative analysis of the UPS and reductive desorption results yields molecular pictures of the proposed interfaces with TP molecules tilted <20° from the surface normal in a herringbone pattern spaced 6.4 Å apart and F5TP molecules in a more disordered arrangement tilted 67° from the surface normal with an intermolecular distance of 10.4 Å. Qualitative surface Raman spectroscopic analysis of in-plane and out-of-plane modes for these systems confirms that TP molecules are oriented more vertical than F5TP molecules in these monolayers.

  5. Polarization-dependent SERS at differently oriented single gold nanorods.

    PubMed

    Jiao, Jiqing; Wang, Xiao; Wackenhut, Frank; Horneber, Anke; Chen, Liuping; Failla, Antonio Virgilio; Meixner, Alfred J; Zhang, Dai

    2012-03-01

    We investigated the influence of the orientation of individual gold nanorods on the polarization-dependent single-particle surface-enhanced Raman spectroscopy (SERS) of adenine. Higher-order laser beams (radial and azimuthal polarizations) have been used in combination with a parabolic mirror-assisted confocal optical microscope. Based on the photoluminescence (PL) patterns of the single gold nanorods and the simulated electric-field distribution in the focus, we distinguished between isolated gold rods and clusters as well as single nanorods with different orientations. We found that for single gold nanorods lying flat on the substrate, the longitudinal particle plasmon resonance (PPR) mode can be excited more efficiently with the in-plane field component in the focus of an azimuthally polarized laser beam, which enables the observation of stronger enhanced adenine Raman spectra from the single gold nanorods compared to the case of a radially polarized beam. PMID:22378600

  6. Hierarchically assembled NiCo@SiO2@Ag magnetic core-shell microspheres as highly efficient and recyclable 3D SERS substrates.

    PubMed

    Zhang, Maofeng; Zhao, Aiwu; Wang, Dapeng; Sun, Henghui

    2015-01-21

    The hierarchically nanosheet-assembled NiCo@SiO2@Ag (NSA) core-shell microspheres have been synthesized by a layer-by-layer procedure at ambient temperature. The mean particle size of NSA microspheres is about 1.7 μm, which is made up of some nanosheets with an average thickness of ∼20 nm. The outer silver shell surface structures can be controlled well by adjusting the concentration of Ag(+) ions and the reaction times. The obtained NSA 3D micro/nanostructures show a structure enhanced SERS performance, which can be attributed to the special nanoscale configuration with wedge-shaped surface architecture. We find that NSA microspheres with nanosheet-assembled shell structure exhibit the highest enhancement efficiency and high SERS sensitivity to p-ATP and MBA molecules. We show that the detection limits for both p-ATP and MBA of the optimized NSA microsphere substrates can approach 10(-7) M. And the relative standard deviation of the Raman peak maximum is ∼13%, which indicates good uniformity of the substrate. In addition, the magnetic NSA microspheres with high saturation magnetization show a quick magnetic response, good recoverability and recyclability. Therefore, such NSA microspheres may have great practical potential applications in rapid and reproducible trace detection of chemical, biological and environment pollutants with a simple portable Raman instrument. PMID:25422829

  7. Electrostatic Assemblies of Well-Dispersed AgNPs on the Surface of Electrospun Nanofibers as Highly Active SERS Substrates for Wide-Range pH Sensing.

    PubMed

    Yang, Tong; Ma, Jun; Zhen, Shu Jun; Huang, Cheng Zhi

    2016-06-15

    Surface-enhanced Raman scattering (SERS) has shown high promise in analysis and bioanalysis, wherein noble metal nanoparticles (NMNPs) such as silver nanoparticles were employed as substrates because of their strong localized surface plasmon resonance (LSPR) properties. However, SERS-based pH sensing was restricted because of the aggregation of NMNPs in acidic medium or biosamples with high ionic strength. Herein, by using the electrostatic interaction as a driving force, AgNPs are assembled on the surface of ethylene imine polymer (PEI)/poly(vinyl alcohol) (PVA) electrospun nanofibers, which are then applied as highly sensitive and reproducible SERS substrate with an enhancement factor (EF) of 10(7)-10(8). When p-aminothiophenol (p-ATP) is used as an indicator with its b2 mode, a good and wide linear response to pH ranging from 2.56 to 11.20 could be available, and the as-prepared nanocomposite fibers then could be fabricated as excellent pH sensors in complicated biological samples such as urine, considering that the pH of urine could reflect the acid-base status of a person. This work not only emerges a cost-effective, direct, and convenient approach to homogeneously decorate AgNPs on the surface of polymer nanofibers but also supplies a route for preparing other noble metal nanofibrous sensing membranes. PMID:27214514

  8. Study of the oxidation effects on isothermal solidification based high temperature stable Pt/In/Au and Pt/In/Ag thick film interconnections on LTCC substrate

    NASA Astrophysics Data System (ADS)

    Kumar, Duguta Suresh; Suri, Nikhil; Khanna, P. K.; Sharma, R. P.

    2016-03-01

    The objective of the presented paper is to determine the oxidized phase compositions of indium lead-free solders during solidification at 190 ° C under room environment with the help of X-ray diffraction (XRD) and Energy dispersive spectroscopy (EDX). Many lead-free solders alloys available oxidizes and have poor wetting properties. The oxidation of pure indium solder foil, Au, Pt, and Ag alloys were identified and investigated, in the process of isothermal solidification based solder joints construction at room environment and humidity. Both EDX and XRD characterization techniques were performed to trace out the amount of oxide levels and variety of oxide formations at solder interface respectively. The paper also aims to report the isothermal solidification technique to provide interconnections to pads on Low temperature co-fired ceramic (LTCC) substrate. It also elaborates advantages of isothermal solidification over the other methods of interconnection. Scanning electron microscope (SEM) used to identify the oxidized spots on the surface of Pt, Ag substrates and In solder. The identified oxides were reported.

  9. Improving photoelectrochemical performance by building Fe{sub 2}O{sub 3} heterostructure on TiO{sub 2} nanorod arrays

    SciTech Connect

    Cao, Chunlan; Hu, Chenguo; Shen, Weidong; Wang, Shuxia; Song, Sihong; Wang, Mingjun

    2015-10-15

    Highlights: • Fe{sub 2}O{sub 3}@TiO{sub 2} heterostructure was fabricated by two-step method. • The photoelectrochemical properties were studied upon visible light irradiation. • Fe{sub 2}O{sub 3}@TiO{sub 2} heterostructure shows superior photoelectrochemical property. • A possible mechanism for enhanced photoelectrochemical property was put forward. - Abstract: Fe{sub 2}O{sub 3}@TiO{sub 2} heterostructure nanorod arrays were synthesized on a fluorine-doped tin oxide conductive (FTO) glass substrate via two-step method for improving photoelectrochemical activity of TiO{sub 2}. The TiO{sub 2} nanorod arrays on FTO substrate were first prepared by hydrothermal method and then Fe{sub 2}O{sub 3} nanoparticles were coated onto the surface of TiO{sub 2} nanorod arrays through chemical bath deposition. The heterojunction yielded a photocurrent density of 39.75 μA cm{sup −2} at a bias potential of 0 V (vs. Ag/AgCl) under visible light irradiation, which is 2.2 times as much as that produced by the pure TiO{sub 2} nanorod arrays. The enhanced photoelectrochemical activity is attributed to the extension of the light response range and efficient separation of photogenerated carriers. Our results have demonstrated the advantage of the novel Fe{sub 2}O{sub 3}@TiO{sub 2} heterojunction and will provide a new path to the fabrication of heterostructural materials.

  10. Role of spacer lengths of gemini surfactants in the synthesis of silver nanorods in micellar media

    NASA Astrophysics Data System (ADS)

    Bhattacharya, Santanu; Biswas, Joydeep

    2011-07-01

    In this work, we have prepared Ag-nanorods using biscationic gemini surfactant micelles as the media by a seed-mediated wet synthesis method. Towards this end, we first synthesized Ag-nanoseeds of diameter ~7 nm stabilized by trisodium citrate (as the capping agent). Then these Ag-nanoseeds were used to synthesize Ag-nanorods of different aspect ratios. With decreasing Ag-nanoseed concentration, the aspect ratios of the Ag-nanorods stabilized by these gemini surfactants increased gradually. Various Ag-nanoseeds and Ag-nanospecies were characterized using UV-Vis spectroscopy (to know the surface plasmon bands), transmission electron microscopy (to find out their particle sizes and distribution), energy-dispersive X-ray spectroscopy and X-ray diffraction. When we used micelles derived from gemini surfactants of shorter spacer -(CH2)n- (n = 2 or 4) to stabilize the Ag-nanorods, the λmax of the longitudinal band shifted more towards the blue region compared to that of the gemini surfactant micelles with a longer spacer -(CH2)n- (n = 5, 12) at a given amount of the Ag-nanoseed solution. So, the growth of Ag-nanorods in the gemini micellar solutions depends on the spacer-chain length of gemini surfactants employed.In this work, we have prepared Ag-nanorods using biscationic gemini surfactant micelles as the media by a seed-mediated wet synthesis method. Towards this end, we first synthesized Ag-nanoseeds of diameter ~7 nm stabilized by trisodium citrate (as the capping agent). Then these Ag-nanoseeds were used to synthesize Ag-nanorods of different aspect ratios. With decreasing Ag-nanoseed concentration, the aspect ratios of the Ag-nanorods stabilized by these gemini surfactants increased gradually. Various Ag-nanoseeds and Ag-nanospecies were characterized using UV-Vis spectroscopy (to know the surface plasmon bands), transmission electron microscopy (to find out their particle sizes and distribution), energy-dispersive X-ray spectroscopy and X-ray diffraction. When

  11. Scanning surface-enhanced Raman spectroscopy (SERS) of chemical agent simulants on templated Au-Ag nanowire substrates

    NASA Astrophysics Data System (ADS)

    Hoffmann, J. A.; Miragliotta, J. A.; Wang, J.; Tyagi, P.; Maddanimath, T.; Gracias, D. H.; Papadakis, S. J.

    2009-05-01

    We report the results of scanning micro-Raman spectroscopy obtained on Au-Ag nanowires for a variety of chemical warfare agent simulants. Rough silver segments embedded in gold nanowires showed enhancement of 105 - 107 and allowed unique identification of 3 of 4 chemical agent simulants tested. These results suggest a promising method for detection of compounds significant for security applications, leading to sensors that are compact and selective.

  12. Electrochromic and transparent conducting oxide nanorods

    NASA Astrophysics Data System (ADS)

    Limmer, Steven J.; Takahashi, Katsunori; Cao, Guozhong

    2003-11-01

    Electrochromic materials are of interest for a wide variety of applications, such as displays and smart windows. Many electrochromic oxide materials are synthesized through sol-gel processing. We have demonstrated a general technique for the synthesis of oxide nanorods using sol electrophoretic deposition with an appropriate template. This technique can be applied for the synthesis of nanorods of electrochromic materials, such as TiO2, V2O5 and Nb2O5, with diameters of ~100 nm and a length of ~10 μm. By attaching these nanorods to a conducting substrate (such as ITO coated glass), it is possible to characterize the electrochromic behavior of these materials via UV-Vis absorbance spectroscopy. A similar technique has been used to make nanorods of the transparent conducting oxide indium tin oxide (ITO), which is often used as a working electrode in electrochromic devices. Such ITO nanorods have diameters of ~75-140 nm and lengths up to 60 μm.

  13. A Multiscale TiO2 Nanorod Array for Ultrasensitive Capture of Circulating Tumor Cells.

    PubMed

    Sun, Na; Li, Xinpan; Wang, Zhili; Zhang, Ruihua; Wang, Jine; Wang, Kewei; Pei, Renjun

    2016-05-25

    In this work, a uniform multiscale TiO2 nanorod array is fabricated to provide a "multi-scale interacting platform" for cell capture, which exhibits excellent capture specificity and sensitivity of the target cells after modification with bovine serum albumin (BSA) and DNA aptamer. After studying the capture performance of the BSA-aptamer TiO2 nanorod substrates and other nanostructured substrates, we can conclude that the multisacle TiO2 nanorod substrates could indeed effectively enhance the capture yields of target cancer cells. The capture yield of artificial blood samples on the BSA-aptamer TiO2 nanorod substrates is up to 85%-95%, revealing the potential application of the TiO2 nanorods on efficient and sensitive capture of rare circulating tumor cells. PMID:27176724

  14. Graded core/shell semiconductor nanorods and nanorod barcodes

    DOEpatents

    Alivisatos, A. Paul; Scher, Erik C.; Manna, Liberato

    2010-12-14

    Graded core/shell semiconductor nanorods and shaped nanorods are disclosed comprising Group II-VI, Group III-V and Group IV semiconductors and methods of making the same. Also disclosed are nanorod barcodes using core/shell nanorods where the core is a semiconductor or metal material, and with or without a shell. Methods of labeling analytes using the nanorod barcodes are also disclosed.

  15. Graded core/shell semiconductor nanorods and nanorod barcodes

    DOEpatents

    Alivisatos, A. Paul; Scher, Erik C.; Manna, Liberato

    2013-03-26

    Graded core/shell semiconductor nanorods and shapped nanorods are disclosed comprising Group II-VI, Group III-V and Group IV semiconductors and methods of making the same. Also disclosed are nanorod barcodes using core/shell nanorods where the core is a semiconductor or metal material, and with or without a shell. Methods of labeling analytes using the nanorod barcodes are also disclosed.

  16. Hydrogen-bond-mediated in situ fabrication of AgNPs/agar/PAN electrospun nanofibers as reproducible SERS substrates.

    PubMed

    Yang, Tong; Yang, Hui; Zhen, Shu Jun; Huang, Cheng Zhi

    2015-01-28

    Reproducibility in surface enhanced Raman scattering (SERS) measurements is a challenge. This work developed a facile way to make highly dispersed uniform silver nanoparticles (AgNPs) loaded in the agar/polyacrylonitrile (PAN) nanofibers by the coupling the electrospinning technology from metal complex-containing polymer solution and in situ photoreductive technique. Agar, as hydrophilic component, was introduced into the electrospinning solution considering that its abundant hydroxyl group sites could greatly improve the contents of silver ions in the polymers because of the rich silver ion chelated with the hydroxyl group, whereas hydrophilic agar was integrated with hydrophobic PAN by -OH···N≡C- hydrogen bonds as a bridge. Meanwhile, the in situ photoreductive reaction was made under different light irradiations such as desk lamp, 365 nm UV-lamp, and 254 nm UV-lamp. High yield of stable AgNPs with highly uniform and dispersion are available in the agar/PAN nanofibers after the in situ photoreductive reaction, supplying the possibility of reproducible SERS signals. To identify that concept of proof, a facile approach for the determination of malachite green (MG) in three environmental practical samples was demonstrated by using the composite nanofibrous material irradiated by 365 nm UV-lamp, giving the minimum detection concentration of MG as low as 0.1 μmol/L with a good linear response ranging from 0.1-100 μmol/L (R(2) = 0.9960). PMID:25546719

  17. Structure and Thermoelectric Properties of Te-Ag-Ge-Sb (TAGS) Materials Obtained by Reduction of Melted Oxide Substrates

    NASA Astrophysics Data System (ADS)

    Kusz, B.; Miruszewski, T.; Bochentyn, B.; Łapiński, M.; Karczewski, J.

    2016-02-01

    Ge0.77Ag0.1Sb0.13Te1 alloy was fabricated by a novel two-step route. Firstly, oxide reagents were melted at high temperature and quenched into pellets. The pellets were milled to powder and then reduced in hydrogen at various temperatures for various periods of time. Energy-dispersive x-ray analysis indicated the possibility of successful fabrication of stoichiometric thermoelectric materials from the Te-Ag-Ge-Sb system. The electrical conductivity and Seebeck coefficient have been determined over the temperature range from 20°C to 340°C in argon atmosphere. It was also shown that, for most of the fabricated samples, the crystallite size as well as electrical parameters such as the electrical conductivity, Seebeck coefficient, and figure of merit ( ZT) increased with increasing reduction time. The highest value of ZT (˜1.0 at 340°C) was obtained for samples reduced in hydrogen atmosphere at 400°C for 20 h and 40 h.

  18. Orientation-and polarization-dependent optical properties of the single Ag nanowire/glass substrate system excited by the evanescent wave

    PubMed Central

    Yang, Mu; Cai, Wei; Wang, Yingjie; Sun, Mengtao; Shang, Guangyi

    2016-01-01

    As an important plasmon one-dimensional material, orientation- and polarization-dependent properties of single Ag nanowires/glass substrate system are investigated by a powerful platform consisting of evanescent wave excitation, near-/far-field detection and a micromanipulator. In the case of the nanowire perpendicular or parallel to the incident plane and p- ors-polarized evanescent excitation respectively, optical properties of the nanowire is measured both in far-field and near-field. For the perpendicular situation, scattering light from the nanowire shows strong dependence on the polarization of incident light, and period patterns along the nanowire are observed both in the near- and far-field. The chain of dipole model is used to explain the origin of this pattern. The discrepancy of the period patterns observed in the near- and far-field is due to the different resolution of the near- and far-field detection. For the parallel case, light intensity from the output end also depends on the incident polarization. Both experimental and calculation results show that the polarization dependence effect results from the surface plasmon excitation. These results on the orientation- and polarization-dependent properties of the Ag nanowires detected by the combination of near- and far-field methods would be helpful to understand interactions of one-dimensional plasmonic nanostructures with light. PMID:27157123

  19. Orientation-and polarization-dependent optical properties of the single Ag nanowire/glass substrate system excited by the evanescent wave

    NASA Astrophysics Data System (ADS)

    Yang, Mu; Cai, Wei; Wang, Yingjie; Sun, Mengtao; Shang, Guangyi

    2016-05-01

    As an important plasmon one-dimensional material, orientation- and polarization-dependent properties of single Ag nanowires/glass substrate system are investigated by a powerful platform consisting of evanescent wave excitation, near-/far-field detection and a micromanipulator. In the case of the nanowire perpendicular or parallel to the incident plane and p- ors-polarized evanescent excitation respectively, optical properties of the nanowire is measured both in far-field and near-field. For the perpendicular situation, scattering light from the nanowire shows strong dependence on the polarization of incident light, and period patterns along the nanowire are observed both in the near- and far-field. The chain of dipole model is used to explain the origin of this pattern. The discrepancy of the period patterns observed in the near- and far-field is due to the different resolution of the near- and far-field detection. For the parallel case, light intensity from the output end also depends on the incident polarization. Both experimental and calculation results show that the polarization dependence effect results from the surface plasmon excitation. These results on the orientation- and polarization-dependent properties of the Ag nanowires detected by the combination of near- and far-field methods would be helpful to understand interactions of one-dimensional plasmonic nanostructures with light.

  20. Orientation-and polarization-dependent optical properties of the single Ag nanowire/glass substrate system excited by the evanescent wave.

    PubMed

    Yang, Mu; Cai, Wei; Wang, Yingjie; Sun, Mengtao; Shang, Guangyi

    2016-01-01

    As an important plasmon one-dimensional material, orientation- and polarization-dependent properties of single Ag nanowires/glass substrate system are investigated by a powerful platform consisting of evanescent wave excitation, near-/far-field detection and a micromanipulator. In the case of the nanowire perpendicular or parallel to the incident plane and p- ors-polarized evanescent excitation respectively, optical properties of the nanowire is measured both in far-field and near-field. For the perpendicular situation, scattering light from the nanowire shows strong dependence on the polarization of incident light, and period patterns along the nanowire are observed both in the near- and far-field. The chain of dipole model is used to explain the origin of this pattern. The discrepancy of the period patterns observed in the near- and far-field is due to the different resolution of the near- and far-field detection. For the parallel case, light intensity from the output end also depends on the incident polarization. Both experimental and calculation results show that the polarization dependence effect results from the surface plasmon excitation. These results on the orientation- and polarization-dependent properties of the Ag nanowires detected by the combination of near- and far-field methods would be helpful to understand interactions of one-dimensional plasmonic nanostructures with light. PMID:27157123

  1. Dispersion and self-assembly of nanospheres and nanorods in polymer nanocomposites

    NASA Astrophysics Data System (ADS)

    Deshmukh, Ranjan Deepak

    2007-12-01

    Polymer nanocomposites are hybrid nanomaterials in which electrical, opto-electronic, magnetic, mechanical and other properties can be precisely tuned by choosing an appropriate combination of nanoparticle (NP) and polymer. This dissertation explores in-situ and ex-situ routes to disperse metal NP in polymers as well as the fundamental thermodynamic and dynamic principles underlying the NP dispersion in polymers. "In-situ" silver NP are prepared by the thermal decomposition of an organometallic precursor (1,1,1,5,5,5-hexafluoroacetylacetonato)silver(I) or (AgHFA) in homopolymer poly(methyl methactyalate), PMMA and block copolymer poly(MMA-b-styrene), PS-b-PMMA films. A range of complementary characterization techniques including Rutherford backscattering spectrometry (RBS), scanning force microscopy (SFM), transmission electron microscopy (TEM), and UV-visible spectroscopy are used to characterize the polymer nanocomposites. The in-situ formed "spherical" silver NP are observed to segregate to the surface and the substrate regions in PMMA and PS-b-PMMA films. By showing that the precursor organizes into aggregates in as-cast films, our experiments uncover the mechanism of NP segregation. Upon annealing, diffusion of the precursor to the surface and substrate occurs concurrently with NP formation resulting in enrichment of Ag at both interfaces. In PS-b-PMMA films, the Ag NP form during the self-assembly of the block copolymer. At the surface, NP organize into well-defined arrays that are guided by the PMMA domains. For the first time, our experiments also show that the kinetics of block copolymer reorganization is slowed down by the incorporation of NP. This dissertation also explores the self-assembly of "ex-situ" synthesized NP with aspect ratio > 1, namely gold nanorods functionalized with poly(ethylene glycol), PEG. After solvent annealing PS-b-PMMA with 5-vol% Au, the nanorods are selectively located and confined in the "lamellar" PMMA domains due to favorable

  2. High performance gold nanorods and silver nanocubes in surface-enhanced Raman spectroscopy of pesticides.

    PubMed

    Costa, Jean Claudio Santos; Ando, Rômulo Augusto; Sant'Ana, Antonio Carlos; Rossi, Liane Marcia; Santos, Paulo Sérgio; Temperini, Márcia Laudelina Arruda; Corio, Paola

    2009-09-14

    The behavior of Au nanorods and Ag nanocubes as analytical sensors was evaluated for three different classes of herbicides. The use of such anisotropic nanoparticles in surface-enhanced Raman scattering (SERS) experiments allows the one to obtain the spectrum of crystal violet dye in the single molecule regime, as well as the pesticides dichlorophenoxyacetic acid (2,4-D), trichlorfon and ametryn. Such metallic substrates show high SERS performance at low analyte concentrations making them adequate for use as analytical sensors. Density functional theory (DFT) calculations of the geometries and vibrational wavenumbers of the adsorbates in the presence of silver or gold atoms were used to elucidate the nature of adsorbate-nanostructure bonding in each case and support the enhancement patterns observed in each SERS spectrum. PMID:19690724

  3. Electromagnetic enhancement of ordered silver nanorod arrays evaluated by discrete dipole approximation.

    PubMed

    Wei, Guoke; Wang, Jinliang; Chen, Yu

    2015-01-01

    The enhancement factor (EF) of surface-enhanced Raman scattering (SERS) from two-dimensional (2D) hexagonal silver nanorod (AgNR) arrays were investigated in terms of electromagnetic (EM) mechanism by using the discrete dipole approximation (DDA) method. The dependence of EF on several parameters, i.e., structure, length, excitation wavelength, incident angle and polarization, and gap size has been investigated. "Hotspots" were found distributed in the gaps between adjacent nanorods. Simulations of AgNR arrays of different lengths revealed that increasing the rod length from 374 to 937 nm (aspect ratio from 2.0 to 5.0) generated more "hotspots" but not necessarily increased EF under both 514 and 532 nm excitation. A narrow lateral gap (in the incident plane) was found to result in strong EF, while the dependence of EF on the diagonal gap (out of the incident plane) showed an oscillating behavior. The EF of the array was highly dependent on the angle and polarization of the incident light. The structure of AgNR and the excitation wavelength were also found to affect the EF. The EF of random arrays was stronger than that of an ordered one with the same average gap of 21 nm, which could be explained by the exponential dependence of EF on the lateral gap size. Our results also suggested that absorption rather than extinction or scattering could be a good indicator of EM enhancement. It is expected that the understanding of the dependence of local field enhancement on the structure of the nanoarrays and incident excitations will shine light on the optimal design of efficient SERS substrates and improved performance. PMID:25821708

  4. Electromagnetic enhancement of ordered silver nanorod arrays evaluated by discrete dipole approximation

    PubMed Central

    Wei, Guoke; Wang, Jinliang

    2015-01-01

    Summary The enhancement factor (EF) of surface-enhanced Raman scattering (SERS) from two-dimensional (2D) hexagonal silver nanorod (AgNR) arrays were investigated in terms of electromagnetic (EM) mechanism by using the discrete dipole approximation (DDA) method. The dependence of EF on several parameters, i.e., structure, length, excitation wavelength, incident angle and polarization, and gap size has been investigated. “Hotspots” were found distributed in the gaps between adjacent nanorods. Simulations of AgNR arrays of different lengths revealed that increasing the rod length from 374 to 937 nm (aspect ratio from 2.0 to 5.0) generated more “hotspots” but not necessarily increased EF under both 514 and 532 nm excitation. A narrow lateral gap (in the incident plane) was found to result in strong EF, while the dependence of EF on the diagonal gap (out of the incident plane) showed an oscillating behavior. The EF of the array was highly dependent on the angle and polarization of the incident light. The structure of AgNR and the excitation wavelength were also found to affect the EF. The EF of random arrays was stronger than that of an ordered one with the same average gap of 21 nm, which could be explained by the exponential dependence of EF on the lateral gap size. Our results also suggested that absorption rather than extinction or scattering could be a good indicator of EM enhancement. It is expected that the understanding of the dependence of local field enhancement on the structure of the nanoarrays and incident excitations will shine light on the optimal design of efficient SERS substrates and improved performance. PMID:25821708

  5. A simple approach for the synthesis of Ag-coated Ni@TiO{sub 2} nanocomposites as recyclable photocatalysts and SERS substrate to monitor catalytic degradation of dye molecules

    SciTech Connect

    Ding, Qianqian; Zhang, Li; Yang, Liangbao

    2014-05-01

    Graphical abstract: - Highlights: • A simple approach was used to synthesize Ag-coated Ni@TiO{sub 2} nanocomposites. • The nanocomposites can be the convenient and effective SERS substrate. • The nanocomposites can be a self-cleaning SERS substrate. • The nanocomposites can monitor the catalytic degradation of dye molecules. - Abstract: In this work, we demonstrate an extremely simple and speedy approach to synthesis Ag-coated Ni@TiO{sub 2} nanocomposites, which can be a convenient and effective substrate for surface enhanced Raman spectroscopy (SERS) observation. Due to possessing the excellent magnetic properties and stable catalytic properties at room temperature, the nanocomposites can clean themselves by photocatalytic degradation of dye molecules under irradiation with UV light into inorganic small molecules for the self-cleaning SERS detection. Furthermore, the nanocomposites can be used as the SERS substrate for monitoring the catalytic degradation of dye molecules.

  6. A Hierarchically Ordered Array of Silver-Nanorod Bundles for Surface-Enhanced Raman Scattering Detection of Phenolic Pollutants.

    PubMed

    Zhu, Chuhong; Meng, Guowen; Zheng, Peng; Huang, Qing; Li, Zhongbo; Hu, Xiaoye; Wang, Xiujuan; Huang, Zhulin; Li, Fadi; Wu, Nianqiang

    2016-06-01

    A hierarchically ordered array of Ag-nanorod bundles is achieved using an inexpensive binary-template-assisted electrodeposition technique. In every bundle, many small gaps are formed between adjacent Ag-nanorods, where "hot spots" are generated. As a result, this plasmonic nanostructure exhibits SERS enhancements of approximately eight orders of magnitude with uniform and reproducible SERS signal throughout the whole chip. PMID:27112639

  7. InN Nanorods and Epi-layers: Similarities and Differences

    SciTech Connect

    Liliental-Weber, Z.; Kryliouk, O.; Park, H.J.; Mangum, J.; Anderson, T.; Schaff, W.

    2007-03-30

    Transmission electron microscopy was applied to study InN nanorods grown on the a-, c-and r-plane of Al{sub 2}O{sub 3}, and (111) Si substrates by non-catalytic, template-free hydride metal-organic vapor phase epitaxy (H-MOVPE). Single crystal nanorod growth was obtained on all substrates. However, the shape of the nanorods varied depending on the substrate used. For example, nanorods grown on r-plane sapphire and (111) Si have sharp tips. In contrast, growth on a- and c- planes of Al{sub 2}O{sub 3} results in flat tips with clear facets on their sides. The structural quality of these nanorods and their growth polarity are compared to crystalline quality, surface roughness, defects and growth polarity of InN layers grown by MBE on the same planes of Al{sub 2}O{sub 3}.

  8. Preparation of gold/silver/titania trilayered nanorods and their photocatalytic activities.

    PubMed

    Horiguchi, Yoshimasa; Kanda, Takashi; Torigoe, Kanjiro; Sakai, Hideki; Abe, Masahiko

    2014-01-28

    Gold/silver/titania trilayered nanorods have been prepared by the successive deposition of silver and titania layers on gold nanorod cores, and their photocatalytic activities were investigated under visible-light illumination (λ > 420 nm). The photocatalytic activity of the trilayered nanorods in the oxidation of 2-propanol depends on both the Au/Ag composition and the thickness of the TiO2 shell. It increases with increasing Ag content up to [Au]/[Ag] = 1:5 (molar ratio) and then decreases with further increasing Ag content. The photocatalytic activity also increases with increasing TiO2 shell thickness up to 10 nm and then decreases with further increases in the shell thickness. These effects were explained by electron-transfer and energy-transfer mechanisms. PMID:24401090

  9. Colloidal luminescent silicon nanorods.

    PubMed

    Lu, Xiaotang; Hessel, Colin M; Yu, Yixuan; Bogart, Timothy D; Korgel, Brian A

    2013-07-10

    Silicon nanorods are grown by trisilane decomposition in hot squalane in the presence of tin (Sn) nanocrystals and dodecylamine. Sn induces solution-liquid-solid nanorod growth with dodecylamine serving as a stabilizing ligand. As-prepared nanorods do not luminesce, but etching with hydrofluoric acid to remove residual surface oxide followed by thermal hydrosilylation with 1-octadecene induces bright photoluminescence with quantum yields of 4-5%. X-ray photoelectron spectroscopy shows that the ligands prevent surface oxidation for months when stored in air. PMID:23731184

  10. Synthesis of silver nanorods using Coscinium fenestratum extracts and its cytotoxic activity against Hep-2 cell line.

    PubMed

    Jacob, S Justin Packia; Mohammed, Harish; Murali, K; Kamarudeen, M

    2012-10-01

    Silver nanorod has attracted considerable interest due to its potential applications in display technologies, thermoelectric and electronic devices, optoelectronic devices and biomedicine. In this study, crystalline silver nanorods were successfully prepared from AgNO(3) using Coscinium fenestratum extract as a reducing agent. The products were characterized by UV-visible spectroscopy, FTIR (Fourier-transform IR) spectroscopy and SEM (scanning electron microscopy) analysis. Bundle-like nanostructures were observed by SEM analysis and the diameters of the nanorods were found to be in the range of 28.5-68.0 nm. The MTT assay results revealed that silver nanorod exhibit significant cytotoxic effect on HEp-2 cells. PMID:22652353

  11. A SERS and electrical sensor from gas-phase generated Ag nanoparticles self-assembled on planar substrates.

    PubMed

    Wang, S; Tay, L-L; Liu, H

    2016-03-01

    Optical excitation of coupled plasmonic nanoparticles supports intense localized electromagnetic "hot-spots" which enable a variety of surface enhanced spectroscopies with the best known example being surface enhanced Raman scattering (SERS), currently of great interest for sensing applications. In this study, we present a novel SERS and electrical dual transduction chemical sensor based on gas-phase generated, negatively charged, silver nanoparticles self-assembled on glass slide forming a close-packed plasmonic monolayer thin-film that supports both SERS and electrical sensing. We demonstrate broad tunability of the localized surface plasmon resonance (LSPR) of the close-packed plasmonic nanoparticle monolayer thin-film sensors through control of the nanoparticle (NP) deposition time which directly influences the plasmonic coupling between neghibouring NPs. This broad tunability supports strong SERS activity from visible to near infrared (NIR) excitation wavelengths. We performed SERS and electrical measurements of a non-resonant molecule 4-mercaptobenzonitrile (4-MBN) as a sample Raman reporter molecule to determine the SERS enhancement factor of our SERS substrate. We measured an average SERS enhancement factor of 10(7) from our close-packed plasmonic nanoparticle monolayer thin-film sensor. Films which were grown below or above one nanoparticle monolayer both exhibited significantly lower SERS performance in one or more of SERS enhancement factor (EF), uniformity or repeatability. Our close-packed plasmonic nanoparticle monolayer thin-film sensors are highly uniform from point-to-point across the entire substrate and showed good reproducibility from batch-to-batch. These qualities are highly desirable for quantifiable detection of chemical and biological molecules. As an example application, this type of substrates provides an affordable and reliable sensing and identification capability for combatting new and emerging chemical and biological threats in

  12. Spontaneous Superlattice Formation in Nanorods through PartialCation Exchange

    SciTech Connect

    Robinson, Richard D.; Sadtler, Bryce; Demchenko, Denis O.; Erdonmez, Can K.; Wang, Lin-Wang; Alivisatos, A. Paul

    2007-03-14

    Lattice mismatch strains are widely known to controlnanoscale pattern formation in heteroepitaxy, but such effects have notbeen exploited in colloidal nanocrystal growth. We demonstrate acolloidal route to synthesizing CdS-Ag2S nanorod superlattices throughpartial cation exchange. Strain induces the spontaneous formation ofperiodic structures. Ab initio calculations of the interfacial energy andmodeling of strain energies show that these forces drive theself-organization. The nanorod superlattices exhibit high stabilityagainst ripening and phase mixing. These materials are tunablenear-infrared emitters with potential applications as nanometer-scaleoptoelectronic devices.

  13. Synthesis of supported silver nano-spheres on zinc oxide nanorods for visible light photocatalytic applications

    SciTech Connect

    Saoud, Khaled; Alsoubaihi, Rola; Bensalah, Nasr; Bora, Tanujjal; Bertino, Massimo; Dutta, Joydeep

    2015-03-15

    Highlights: • Synthesis of supported Ag NPs on ZnO nanorods using open vessel microwave reactor. • Use of the Ag/ZnO NPs as an efficient visible light photocatalyst. • Complete degradation of methylene blue in 1 h with 0.5 g/L Ag/ZnO NPs. - Abstract: We report the synthesis of silver (Ag) nano-spheres (NS) supported on zinc oxide (ZnO) nanorods through two step mechanism, using open vessel microwave reactor. Direct reduction of ZnO from zinc nitrates was followed by deposition precipitation of the silver on the ZnO nanorods. The supported Ag/ZnO nanoparticles were then characterized by electron microscopy, X-ray diffraction, FTIR, photoluminescence and UV–vis spectroscopy. The visible light photocatalytic activity of Ag/ZnO system was investigated using a test contaminant, methylene blue (MB). Almost complete removal of MB in about 60 min for doses higher than 0.5 g/L of the Ag/ZnO photocatalyst was achieved. This significant improvement in the photocatalytic efficiency of Ag/ZnO photocatalyst under visible light irradiation can be attributed to the presence of Ag nanoparticles on the ZnO nanoparticles which greatly enhances absorption in the visible range of solar spectrum enabled by surface plasmon resonance effect from Ag nanoparticles.

  14. 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. PMID:26807679

  15. Orientation-Dependent Structural Properties and Growth Mechanism of ZnO Nanorods

    NASA Astrophysics Data System (ADS)

    Yu, H.-J.; Jeong, E.-S.; Park, S.-H.; Seo, S.-Y.; Kim, S.-H.; Han, S.-W.

    2007-01-01

    We present the local structural properties of ZnO nanorods studied by using extended x-ray absorption fine structure (EXAFS). Vertically aligned ZnO nanorods were fabricated on Al2O3 substrates by a catalyst free metal organic chemical vapor deposition (MOCVD). The polarized EXAFS measurements on the ZnO nanorods were performed at Zn K-edge. The polarized EXAFS study revealed that the nanorods had a wurtzite structure, and that there were substantial amount of structural disorders in Zn-O pairs in the beginning of the nanorod growth. The EXAFS measurements revealed that the orientation-dependent disorders of the Zn-O pairs were directly related to the growth mechanism and crystal quality of the ZnO nanorods.

  16. Effect of Reflow Time on Wetting Behavior, Microstructure Evolution, and Joint Strength of Sn-2.5Ag-0.5Cu Solder on Bare and Nickel-Coated Copper Substrates

    NASA Astrophysics Data System (ADS)

    Sona, Mrunali; Prabhu, K. Narayan

    2016-04-01

    The effect of reflow time on wetting behavior of Sn-2.5Ag-0.5Cu lead-free solder on bare and nickel-coated copper substrates has been investigated. The solder alloy was reflowed at 270°C for various reflow times of 10 s, 100 s, 300 s, and 500 s. On bare copper substrate, the intermetallic compound (IMC) thickness increased with increase in reflow time, whereas on Ni-coated Cu substrate, the IMC thickness increased up to 300 s followed by a drop for solder alloy reflowed for 500 s. The spreading behavior of the solder alloy was categorized into capillary, gravity (diffusion), and viscous zones. Gravity zone was obtained from 3.8 ± 0.43 s to 38.97 ± 3.38 s and from 5.99 ± 0.5 s to 77.82 ± 8.84 s for the Sn-2.5Ag-0.5Cu/Cu and Sn-2.5Ag-0.5Cu/Ni/Cu system, respectively. Sn-2.5Ag-0.5Cu solder alloy was also reflowed for the period corresponding to the end of the gravity zone (40 s and 80 s on bare and Ni-coated Cu, respectively). The joint strength was maximum at reflow time of 40 s and 80 s for the Sn-2.5Ag-0.5Cu/Cu and Sn-2.5Ag-0.5Cu/Ni/Cu system, respectively. The dynamic contact angle at the end of the gravity (diffusion) zone (θ gz) was found to be a better parameter compared with the stabilized contact angle (θ f) to assess the effect of the wettability of the liquid solder on the microstructure and joint strength. The present investigation reveals the significance of the gravity zone in assessment of optimum reflow time for lead-free solder alloys.

  17. Effect of Reflow Time on Wetting Behavior, Microstructure Evolution, and Joint Strength of Sn-2.5Ag-0.5Cu Solder on Bare and Nickel-Coated Copper Substrates

    NASA Astrophysics Data System (ADS)

    Sona, Mrunali; Prabhu, K. Narayan

    2016-07-01

    The effect of reflow time on wetting behavior of Sn-2.5Ag-0.5Cu lead-free solder on bare and nickel-coated copper substrates has been investigated. The solder alloy was reflowed at 270°C for various reflow times of 10 s, 100 s, 300 s, and 500 s. On bare copper substrate, the intermetallic compound (IMC) thickness increased with increase in reflow time, whereas on Ni-coated Cu substrate, the IMC thickness increased up to 300 s followed by a drop for solder alloy reflowed for 500 s. The spreading behavior of the solder alloy was categorized into capillary, gravity (diffusion), and viscous zones. Gravity zone was obtained from 3.8 ± 0.43 s to 38.97 ± 3.38 s and from 5.99 ± 0.5 s to 77.82 ± 8.84 s for the Sn-2.5Ag-0.5Cu/Cu and Sn-2.5Ag-0.5Cu/Ni/Cu system, respectively. Sn-2.5Ag-0.5Cu solder alloy was also reflowed for the period corresponding to the end of the gravity zone (40 s and 80 s on bare and Ni-coated Cu, respectively). The joint strength was maximum at reflow time of 40 s and 80 s for the Sn-2.5Ag-0.5Cu/Cu and Sn-2.5Ag-0.5Cu/Ni/Cu system, respectively. The dynamic contact angle at the end of the gravity (diffusion) zone ( θ gz) was found to be a better parameter compared with the stabilized contact angle ( θ f) to assess the effect of the wettability of the liquid solder on the microstructure and joint strength. The present investigation reveals the significance of the gravity zone in assessment of optimum reflow time for lead-free solder alloys.

  18. Optimization of Nb{sub 2}O{sub 5}/Ag/Nb{sub 2}O{sub 5} multilayers as transparent composite electrode on flexible substrate with high figure of merit

    SciTech Connect

    Dhar, Aritra; Alford, T. L.

    2012-11-15

    Different multilayer structures of Nb{sub 2}O{sub 5}/Ag/Nb{sub 2}O{sub 5} have been deposited onto flexible substrates by sputtering at room temperature to develop an indium free transparent composite electrode. The effect of Ag thickness on the electrical and optical properties of the multilayer stack has been studied in accordance with the Ag morphology. The critical thickness of Ag to form a continuous conducting layer is found to be 9.5 nm. A new conduction mechanism has been proposed to describe the conduction before and after the critical thickness. The effective Hall resistivity of the optimized films is as low as 6.44 Multiplication-Sign 10{sup -5} Ohm-Sign -cm with a carrier concentration and mobility of 7.4 Multiplication-Sign 10{sup 21} cm{sup -3} and 13.1 cm{sup 2} /V-s, respectively, at the critical Ag layer thickness. The multilayer stack has been optimized to obtain a sheet resistance of 7.2 Ohm-Sign /sq and an average optical transmittance of 86% at 550 nm without any substrate heating or post-annealing process. The Haacke figure of merit (FOM) has been calculated for the films, and the multilayer with a 9.5 nm thick Ag layer has the highest FOM at 31.5 Multiplication-Sign 10-3 {Omega}{sup -1}, which is one of the highest FOM values reported for TCE deposited at room temperature on a flexible substrate.

  19. Watching single gold nanorods grow.

    PubMed

    Wei, Zhongqing; Qi, Hua; Li, Min; Tang, Bochong; Zhang, Zhengzheng; Han, Ruiling; Wang, Jiaojiao; Zhao, Yuliang

    2012-05-01

    The consecutive evolution process of single gold nanorods is monitored using atomic force microscopy (AFM). The single-crystal gold nanorods investigated are grown directly on surfaces to which gold seed particles are covalently linked. The growth kinetics for single nanorods is derived from the 3D information recorded by AFM. A better understanding of the seed-mediated growth mechanism may ultimately lead to the direct growth of aligned nanorods on surfaces. PMID:22378704

  20. Core-shell-shell nanorods for controlled release of silver that can serve as a nanoheater for photothermal treatment on bacteria.

    PubMed

    Hu, Bo; Wang, Ning; Han, Lu; Chen, Ming-Li; Wang, Jian-Hua

    2015-01-01

    A novel bactericidal material comprising rod-shaped core-shell-shell Au-Ag-Au nanorods is constructed as a nanoheater in the near-infrared (NIR) region. The outer Au shell melts under laser irradiation and results in exposure of the inner Ag shell, facilitating the controlled release of the antibacterial Ag shell/layer or Ag(+). This results in the Au-Ag-Au nanorods having a favorable bactericidal ability as it combines the features of physical photothermal ablation sterilization of the outer Au shell and the antibacterial effect of the inner Ag shell or Ag(+) to the surrounding bacteria. The sterilizing ability of Au-Ag-Au nanorods is investigated with Escherichia coli O157:H7 as a model bacterial strain. Under low-power NIR laser irradiation (785 nm, 50 mW cm(-2)), the Au-Ag-Au nanoheater exhibits a higher photothermal conversion efficiency (with a solution temperature of 44°C) with respect to that for the Au-Ag nanorods (39°C). Meanwhile, a much improved stability with respect to Au-Ag nanorods is observed, i.e., 16 successive days of monitoring reveal virtually no change in the ultraviolet-visible spectrum of Au-Ag-Au nanorods, while a significant drop in absorption along with a 92 nm red shift of Localized Surface Plasmon Resonance is recorded for the Au-Ag nanorods. This brings an increasing bactericidal efficiency and long-term stability for the Au-Ag-Au nanorods. At a dosage of 10 μg ml(-1), a killing rate of 100% is reached for the E. coli O157:H7 cells under 20 min of irradiation. The use of Au-Ag-Au nanorods avoids the abuse of broad-spectrum antibiotics and reduces the damage of tissues by alleviating the toxicity of silver under controlled release and by the use of low-power laser irradiation. These features could make the bimetallic core-shell-shell nanorods a favorable nanoheater for in vivo biomedical applications. PMID:25219350

  1. Effect of thicknesses of copper catalyst and oxide sublayer on morphology of ZnO nanorods

    NASA Astrophysics Data System (ADS)

    Lyanguzov, N. V.; Kaydashev, V. E.; Kaidashev, E. M.; Abdulvakhidov, K. G.

    2011-03-01

    The influence of thicknesses of a ZnO sublayer and a copper catalyst film on the morphology of ZnO nanorods grown by carbothermal synthesis on α-Al2O3(11-20) substrates has been studied. An increase in the Cu catalyst film thickness leads to a growth in the diameters, heights, and surface density of nanorods. As the ZnO sublayer thickness is increased, the average diameter of nanorods also increases, while their lengths and surface density decrease. The effect of elevated temperatures on the thermal decomposition of ultrathin Cu films deposited on α-Al2O3 substrates has been studied. The photoluminescence characteristics of nanorod arrays have been measured at high levels of optical pumping. An increase in the pumping level to 250-280 kW/cm2 leads to superluminescence of the nanorods.

  2. Effects of Microstructure and Loading on Fracture of Sn-3.8Ag-0.7Cu Joints on Cu Substrates with ENIG Surface Finish

    NASA Astrophysics Data System (ADS)

    Huang, Z.; Kumar, P.; Dutta, I.; Sidhu, R.; Renavikar, M.; Mahajan, R.

    2014-12-01

    When dropped, electronic packages often undergo failure by propagation of an interfacial crack in solder joints under a combination of tensile and shear loading. Hence, it is crucial to understand and predict the fracture behavior of solder joints under mixed-mode high-rate loading conditions. In this work, the effects of the loading conditions (strain rate and loading angle) and microstructure [interfacial intermetallic compound (IMC) morphology and solder yield strength] on the mixed-mode fracture toughness of Sn-3.8 wt.%Ag-0.7 wt.%Cu solder joints sandwiched between two Cu substrates with electroless nickel immersion gold (ENIG) metallization have been studied, and compared with the fracture behavior of joints attached to bare Cu. Irrespective of the surface finish, the fracture toughness of the solder joints decreased monotonically with strain rate and mode-mixity, both resulting in increased fracture proportion through the interfacial IMC layer. Furthermore, the proportion of crack propagation through the interfacial IMC layer increased with increase in the thickness and the roughness of the interfacial IMC layer and the yield strength of the solder, resulting in a decrease in the fracture toughness of the joint. However, under most conditions, solder joints with ENIG finish showed higher resistance to fracture than joints attached directly to Cu substrates without ENIG metallization. Based on the experimental observations, a fracture mechanism map is constructed correlating the yield strength of the solder, the morphology and thickness of the interfacial IMC, and the fracture mechanisms as well as the fracture toughness values for different solder joints under mode I loading.

  3. Visible light driven photocatalysis and antibacterial activity of AgVO{sub 3} and Ag/AgVO{sub 3} nanowires

    SciTech Connect

    Singh, Anamika; Dutta, Dimple P.; Ballal, A.; Tyagi, A.K.; Fulekar, M.H.

    2014-03-01

    Graphical abstract: - Highlights: • Ag/AgVO{sub 3} and pure AgVO{sub 3} nanowires synthesized by sonochemical process. • Characterization done using XRD, SEM, TEM, EDX and BET analysis. • Visible light degradation of RhB by Ag/AgVO{sub 3} within 45 min. • Antibacterial activity of Ag/AgVO{sub 3} demonstrated. - Abstract: Ag/AgVO{sub 3} nanowires and AgVO{sub 3} nanorods were synthesized in aqueous media via a facile sonochemical route. The as-synthesized products were characterized by X-ray diffraction, Brunauer–Emmett–Teller surface area analysis, scanning electron microscopy together with an energy dispersion X-ray spectrum analysis, transmission electron microscopy and UV–vis diffuse reflectance spectroscopy. The results revealed that inert atmosphere promotes the formation of Ag/AgVO{sub 3} nanowires. The photocatalytic studies revealed that the Ag/AgVO{sub 3} nanowires exhibited complete photocatalytic degradation of Rhodamine B within 45 min under visible light irradiation. The antibacterial activity of Ag/AgVO{sub 3} nanowires was tested against Escherechia coli and Bacillus subtilis. The minimum growth inhibitory concentration value was found to be 50 and 10 folds lower than for the antibiotic ciprofloxacin for E. coli and B. subtilis, respectively. The antibacterial properties of the β-AgVO{sub 3} nanorods prove that in case of the Ag dispersed Ag/AgVO{sub 3} nanowires, the enhanced antibacterial action is also due to contribution from the AgVO{sub 3} support.

  4. Effect of growth time on ZnO nanorod arrays by a facile sonicated sol-gel immersion technique

    NASA Astrophysics Data System (ADS)

    Malek, M. F.; Mamat, M. H.; Musa, M. Z.; Ishak, A.; Saurdi, I.; Alrokayan, Salman A. H.; Khan, Haseeb A.; Rusop, M.

    2016-07-01

    A facile sonicated sol-gel immersion technique has been presented for synthesizing ZnO nanorod arrays with controllable diameter and lengths on glass substrates. A sol-gel dip-coating deposition was first used to grow a thin layer of ZAO nanocrystals on substrate serving as seeds for the subsequent growth of the nanorod arrays. The effect of growth time of the ZnO nanorod arrays on the ZAO seed layer were investigated. The optical transmission properties of the ZnO nanorods has been investigated. The thickness of the nanorods can be controlled by the growth time. These highly oriented ZnO nanorod arrays are potential for the creation of functional materials, such as the electrode of the solar cells, optoelectronic devices and etc.

  5. Differentiation and classification of bacteria using vancomycin functionalized silver nanorods array based surface-enhanced Raman spectroscopy and chemometric analysis.

    PubMed

    Wu, Xiaomeng; Huang, Yao-Wen; Park, Bosoon; Tripp, Ralph A; Zhao, Yiping

    2015-07-01

    Twenty seven different bacteria isolates from 12 species were analyzed using intrinsic surface-enhanced Raman scattering (SERS) spectra with recently developed vancomycin coated silver nanorod (VAN AgNR) substrates. The VAN AgNR substrates could generate reproducible SERS spectra of the bacteria with little to no interference from the environment or bacterial by-products as compared to the pristine substrates. By taking advantage of the structural composition of the cellular wall which varies from species to species, the differentiation of bacterial species is demonstrated by using chemometric analyses on those spectra. A second chemometric analysis step within the species cluster is able to differentiate serotypes and strains. The spectral features used for serotype differentiation arises from the surface proteins, while Raman peaks from adenine dominate the differentiation of strains. In addition, due to the intrinsic structural differences in the cell walls, the SERS spectra can distinguish Gram-positive from Gram-negative bacteria with high sensitivity and specificity, as well as 100% accuracy on predicting test samples. Our results provide important insights for using SERS as a bacterial diagnostic tool and further guide the design of a SERS-based detection platform. PMID:25882413

  6. Antibacterial activity of ordered gold nanorod arrays.

    PubMed

    Zhu, Yuejing; Ramasamy, Mohankandhasamy; Yi, Dong Kee

    2014-09-10

    Well-packed two- and three-dimensional (2D and 3D) gold nanorod (AuNR) arrays were fabricated using confined convective arraying techniques. The array density could be controlled by changing the concentration of the gold nanorods solution, the velocity of the moving substrate, and the environment air-temperature. The hydrophilic behavior of glass substrates before and after surface modification was studied through contact angle measurements. The affinity and alignment of the AuNR arrays with varying nanorod concentrations and the resulting different array densities were studied using field emission scanning electron microscopy (FE-SEM). Under stable laser intensity irradiation, the photothermal response of the prepared arrays was measured using a thermocouple and the results were analyzed quantitatively. Synthesized AuNR arrays were added to Escherichia coli (E. coli) suspensions and evaluated for photothermal bactericidal activity before and after laser irradiation. The results showed promising bactericidal effect. The severity of pathogen destruction was measured and quantified using fluorescence microscopy, bioatomic force microscopy (Bio-AFM) and flow cytometry techniques. These results indicated that the fabricated AuNR arrays at higher concentrations were highly capable of complete bacterial destruction by photothermal effect compared to the low concentration AuNR arrays. Subsequent laser irradiation of the AuNR arrays resulted in rapid photoheating with remarkable bactericidal activity, which could be used for water treatment to produce microbe-free water. PMID:25148531

  7. Gold nanorod-templated synthesis of polymetallic hollow nanostructures with enhanced electrocatalytic performance

    NASA Astrophysics Data System (ADS)

    Guo, Xia; Ye, Wei; Zhu, Rui; Wang, Wenxin; Xie, Fang; Sun, Hongyan; Zhao, Qing; Ding, Yi; Yang, Jian

    2014-09-01

    Anisotropic polymetallic hollow nanostructures are highly desired for many applications because of their unique morphology, large specific surface areas and attractive electronic effects. Here, a simple method using gold nanorods as a self-sacrificed template has been developed for the fabrication of hollow dumbbell-like nanorods of Au@PtAg. The formation of the hollow structures involves the growth of another metallic shell first, and then the etching of gold nanorods, which is induced by oxygen and ascorbic acid. The lattice mismatch and cohesive energy of the shell, along with its surface passivation, greatly affect the subsequent etching and the resulting products, as has been demonstrated by a positive control in the case of Rh and a negative control in the case of Pd. Hollow dumbbell-like nanorods of Au@PtAg show great enhancement for the dehydrogenation pathway in the oxidation of formic acid, as compared to solid Au@PtAg nanorods, PtAu nanotubes and commercial Pt/C.Anisotropic polymetallic hollow nanostructures are highly desired for many applications because of their unique morphology, large specific surface areas and attractive electronic effects. Here, a simple method using gold nanorods as a self-sacrificed template has been developed for the fabrication of hollow dumbbell-like nanorods of Au@PtAg. The formation of the hollow structures involves the growth of another metallic shell first, and then the etching of gold nanorods, which is induced by oxygen and ascorbic acid. The lattice mismatch and cohesive energy of the shell, along with its surface passivation, greatly affect the subsequent etching and the resulting products, as has been demonstrated by a positive control in the case of Rh and a negative control in the case of Pd. Hollow dumbbell-like nanorods of Au@PtAg show great enhancement for the dehydrogenation pathway in the oxidation of formic acid, as compared to solid Au@PtAg nanorods, PtAu nanotubes and commercial Pt/C. Electronic

  8. Optoacoustic detection of viral antigens using targeted gold nanorods

    NASA Astrophysics Data System (ADS)

    Maswadi, Saher; Woodward, Lee; Glickman, Randolph D.; Barsalou, Norman

    2009-02-01

    We are detecting antigens (Ag), isolated from infectious organisms, utilizing laser optoacoustic spectroscopy and antibody-coupled gold nanorod (NR) contrast agents specifically targeted to the antigen of interest. We have detected, in clinical ocular samples, both Herpes Simplex Virus Type 1 and 2 (HSV-1 and HSV-2) . A monoclonal antibody (Ab) specific to both HSV-1 and HSV-2 was conjugated to gold nanorods to produce a targeted contrast agent with a strong optoacoustic signal. Elutions obtained from patient corneal swabs were adsorbed in standard plastic micro-wells. An immunoaffinity reaction was then performed with the functionalized gold nanorods, and the results were probed with an OPO laser, emitting wavelengths at the peak absorptions of the nanorods. Positive optoacoustic responses were obtained from samples containing authentic (microbiologically confirmed) HSV-1 and HSV-2. To obtain an estimate of the sensitivity of the technique, serial dilutions from 1 mg/ml to 1 pg/ml of a C. trachomatis surface Ag were prepared, and were probed with a monoclonal Ab, specific to the C. trachomatis surface Ag, conjugated to gold nanorods. An optoacoustic response was obtained, proportional to the concentration of antigen, and with a limit of detection of about 5 pg/ml. The optoacoustic signals generated from micro-wells containing albumin or saline were similar to those from blank wells. The potential benefit of this method is identify viral agents more rapidly than with existing techniques. In addition, the sensitivity of the assay is comparable or superior to existing colorimetric- or fluorometric-linked immunoaffinity assays.

  9. Development of a physical and electronic model for RuO 2 nanorod rectenna devices

    NASA Astrophysics Data System (ADS)

    Dao, Justin

    Ruthenium oxide (RuO2) nanorods are an emergent technology in nanostructure devices. As the physical size of electronics approaches a critical lower limit, alternative solutions to further device miniaturization are currently under investigation. Thin-film nanorod growth is an interesting technology, being investigated for use in wireless communications, sensor systems, and alternative energy applications. In this investigation, self-assembled RuO2 nanorods are grown on a variety of substrates via a high density plasma, reactive sputtering process. Nanorods have been found to grow on substrates that form native oxide layers when exposed to air, namely silicon, aluminum, and titanium. Samples were analyzed with Scanning Electron Microscopy (SEM) and Transmission Electron Microscopy (TEM) techniques. Conductive Atomic Force Microscopy (C-AFM) measurements were performed on single nanorods to characterize structure and electrical conductivity. The C-AFM probe tip is placed on a single nanorod and I-V characteristics are measured, potentially exhibiting rectifying capabilities. An analysis of these results using fundamental semiconductor physics principles is presented. Experimental data for silicon substrates was most closely approximated by the Simmons model for direct electron tunneling, whereas that of aluminum substrates was well approximated by Fowler-Nordheim tunneling. The native oxide of titanium is regarded as a semiconductor rather than an insulator and its ability to function as a rectifier is not strong. An electronic model for these nanorods is described herein.

  10. Facile fabrication of rutile monolayer films consisting of well crystalline nanorods by following an IL-assisted hydrothermal route

    SciTech Connect

    Peng Peng; Liu Xiaodi; Sun, Chuansheng; Ma Jianmin; Zheng Wenjun

    2009-05-15

    In this study, rutile films consisting of rectangular nanorods were facilely deposited on glass substrates from strongly acid solution of TiCl{sub 4}. The highly ordered array of nanorods was realized in presence of ionic liquid (IL) of [Bmim]Br by following a hydrothermal process. In this process, Degussa P25 nanoparticles served as seeds that were pre-deposited on the substrates to facilitate the array of rutile nanorods. X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and Raman spectrum were used to characterize the obtained nanorod films. The measurements showed that the nanorods were rectangular with width of 100-200 nm and length of more than 1 {mu}m, and grew up typically along c-axis to form the arrays against the substrate. The presence of IL was found vital for the formation of rutile nanorods, and the suitable molar ratio of [Bmim]Br to TiCl{sub 4} ranged from 500:1 to 1500:1. The excessive [Bmim]Br may hinder the precipitation of rutile particles. - Graphical abstract: The rutile film consisting of rectangular nanorods is successfully deposited on glass substrate in presence of ionic liquid (IL) of [Bmim]Br. The nanorods were rectangular with width of 100-200 nm and length of more than 1 {mu}m, which grew up typically along c-axis to form the arrays against the substrate.

  11. Photoluminescence and field emission of 1D ZnO nanorods fabricated by thermal evaporation

    NASA Astrophysics Data System (ADS)

    Wang, B.; Jin, X.; Ouyang, Z. B.; Xu, P.

    2012-07-01

    Four kinds of new one-dimensional nanostructures, celery-shaped nanorods, needle-shaped nanorods, twist fold-shaped nanorods, and awl-shaped nanorods of ZnO, have been grown on single silicon substrates by an Au catalyst assisted thermal evaporation of ZnO and active carbon powders. The morphology and structure of the prepared nanorods are determined on the basis of field-emission scanning electron microscopy (FESEM) and x-ray diffraction (XRD). The photoluminescence spectra (PL) analysis noted that UV emission band is the band-to-band emission peak and the emission bands in the visible range are attributed to the oxygen vacancies, Zn interstitials, or impurities. The field-emission properties of four kinds of ZnO nanorods have been invested and the awl-shaped nanorods of ZnO have preferable characteristics due to the smallest emitter radius on the nanoscale in the tip in comparison with other nanorods. The growth mechanism of the ZnO nanorods can be explained on the basis of the vapor-liquid-solid (VLS) processes.

  12. Growth of vertically aligned ZnO nanorods using textured ZnO films

    PubMed Central

    2011-01-01

    A hydrothermal method to grow vertical-aligned ZnO nanorod arrays on ZnO films obtained by atomic layer deposition (ALD) is presented. The growth of ZnO nanorods is studied as function of the crystallographic orientation of the ZnO films deposited on silicon (100) substrates. Different thicknesses of ZnO films around 40 to 180 nm were obtained and characterized before carrying out the growth process by hydrothermal methods. A textured ZnO layer with preferential direction in the normal c-axes is formed on substrates by the decomposition of diethylzinc to provide nucleation sites for vertical nanorod growth. Crystallographic orientation of the ZnO nanorods and ZnO-ALD films was determined by X-ray diffraction analysis. Composition, morphologies, length, size, and diameter of the nanorods were studied using a scanning electron microscope and energy dispersed x-ray spectroscopy analyses. In this work, it is demonstrated that crystallinity of the ZnO-ALD films plays an important role in the vertical-aligned ZnO nanorod growth. The nanorod arrays synthesized in solution had a diameter, length, density, and orientation desirable for a potential application as photosensitive materials in the manufacture of semiconductor-polymer solar cells. PACS 61.46.Hk, Nanocrystals; 61.46.Km, Structure of nanowires and nanorods; 81.07.Gf, Nanowires; 81.15.Gh, Chemical vapor deposition (including plasma-enhanced CVD, MOCVD, ALD, etc.) PMID:21899743

  13. Synthesis and Enhanced Light Absorption of Alumina Matrix Nanocomposites Containing Multilayer Oxide Nanorods and Silver Nanoparticles

    SciTech Connect

    Gan, Y.X.; Zhang, L.; Zeng, X.; Su, L.; Yang, L.; Gan, B.J.

    2011-11-01

    In this paper, multilayer oxide nanorods were deposited in the nanopores of anodic aluminum oxide (AAO) via solution infiltration followed by heat treatment. The nanorods have a core-shell structure. First, the shell (nanotube) with the thickness of about 40 nm was made of TiO{sub 2} through the hydrolysis of (NH{sub 4}){sub 2}TiF{sub 6}. Second, silver nanoparticles with the diameter of about 3 nm were added into the TiO{sub 2} layer through thermal decomposition of AgNO{sub 3} at elevated temperatures. Then, cylindrical cores (nanorods) of CoO and ZnO with 200 nm diameter were prepared, respectively. Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) were used to characterize the structure and composition of the nanorods. UV-vis light absorption measurements in the wavelength range from 350 to 1000 nm were performed to study the effect of nanorod and nanoparticle addition on the light absorption property of the alumina nanocomposites. It is found that CoO nanorods increase the light absorption of the alumina matrix composite in the wavelength range from 500 nm to 800 nm, but the TiO{sub 2} shell does not increase the light absorption much. The ZnO nanorods do not change the light absorption either. However, the addition of silver nanoparticles significantly enhances light absorption of both AAO/TiO{sub 2}/Ag/CoO and AAO/TiO{sub 2}/Ag/ZnO nanocomposites. This increase in the visible light absorption reveals that there exists surface plasmon around the fine silver nanoparticles in the nanorods.

  14. Optoacoustic sensing of ocular bacterial antigen using targeted gold nanorods

    NASA Astrophysics Data System (ADS)

    Maswadi, Saher; Page, Leland; Woodward, Lee; Glickman, Randolph D.; Barsalou, Norman

    2008-02-01

    Bacterial contamination can be detected using a minimally invasive optical method, based on laser-induced optoacoustic spectroscopy, to probe for specific antigens associated with a specific infectious agent. As a model system, we have used a surface antigen (Ag), isolated from Chlamydia trachomatis, and a complementary antibody (Ab). A preparation of 0.2 mg/ml of monoclonal Ab specific to the C. trachomatis surface Ag was conjugated to gold nanorods using standard commercial reagents, in order to produce a targeted contrast agent with a strong optoacoustic signal. The C. trachomatis Ag was absorbed in standard plastic microwells, and the binding of the complementary Ab-nanorod conjugate was tested in an immunoaffinity assay. Optoacoustic signals were elicited from the bound nanorods, using an optical parametric oscillator (OPO) laser system as the optical pump. The wavelength tuneability of the OPO optimized the spectroscopic measurement by exciting the nanorods at their optical absorption maxima. Optoacoustic responses were measured in the microwells using a probe beam deflection technique. Immunoaffinity assays were performed on several dilutions of purified C. trachomatis antigen ranging from 50 μg/ml to 1 pg/ml, in order to determine the detection limit for the optoacoustic-based assay. Only when the antigen was present, and the complementary Ab-NR reagent was introduced into the microwell, was an enhanced optoacoustic signal obtained, which indicated specific binding of the Ab-NR complex. The limit of detection with the current system design is between 1 and 5 pg/ml of bacterial Ag.

  15. Size and dielectric-environment dependence of transversal resonance modes of localized surface plasmons in silver nanorods.

    PubMed

    Yu, Jie; Zhang, Junxi; Zhang, Lide; Jia, Junhui; Xu, Wei; Wang, Junfeng; Fei, Guangtao

    2016-06-20

    Tuning transversal resonance modes of localized surface plasmons (LSPs) by the size and the ambient dielectric medium of Ag nanorods is presented. It is found that the resonance wavelength and intensity of the transversal modes of LSPs are closely related to the dimensions of the Ag nanorods embedded in anodic aluminum oxide membranes. The transversal resonance peak exhibits obvious redshifts from 365 to 396 nm with increasing nanorod diameter from 40 to 80 nm, and the resonance intensity remarkably enhances with increasing nanorod diameter. In addition, it is observed that the transversal resonance modes of LSPs in Ag nanorods are strongly sensitive to their surrounding dielectric medium such as water, ethanol, and cetyltrimethylammonium bromide, and the transversal resonance peak distinctly redshifts from 422 to 467 nm when the refractive index of the dielectric medium increases from 1.342 to 1.435. As a result, a refractive index sensitivity of up to 484 nm/RIU can be achieved based on the transversal resonance modes. The transverse resonance modes of LSPs in the Ag nanorods can be used for sensitive quantification of chemical and biological species. PMID:27409112

  16. High-performance GaN-based light-emitting diodes on patterned sapphire substrate with a novel hybrid Ag mirror and atomic layer deposition-TiO2/Al2O3 distributed Bragg reflector backside reflector

    NASA Astrophysics Data System (ADS)

    Guo, Hao; Chen, Hongjun; Zhang, Xiong; Zhang, Peiyuan; Liu, Jianjun; Liu, Honggang; Cui, Yiping

    2013-06-01

    GaN-based light-emitting diodes (LED) on a patterned sapphire substrate with a novel hybrid atomic layer deposition (ALD)-TiO2Al2O3 distributed Bragg reflector (DBR) and Ag mirror have been proposed and fabricated. Due to the excellent thickness uniformity of ALD for the proposed reflector, high reflectivity over 99.3% at an incident angle of 5 deg has been achieved. It was also found that the reflectivity of a backside reflector with an Ag mirror slightly depends on incident light wavelength and incident angle. Moreover, because of the good adhesion between TiO2/Al2O3 DBR and the Ag mirror, the fabrication process was simplified and reliable. With a 60 mA current injection, an enhancement of 5.2%, 8.9%, and 47.1% in light output power (LOP) at the 460 nm wavelength was realized for the proposed LED with Ag mirror and 3-pair ALD-TiO2Al2O3 DBR as compared with a LED with a traditional Ag mirror and 3-pair TiO2/SiO2 DBR, with Al mirror and 3-pair ALD-TiO2Al2O3 DBR, and without backside reflector, respectively. This result shows that the ALD-TiO/O3 DBR can be used to enhance the LOP greatly and improve adhesion between the sapphire substrate and the metallic mirror, and thus is very promising for fabricating high performance GaN-based LEDs.

  17. UV light sensing properties of Sm doped vertically aligned ZnO nanorod arrays

    SciTech Connect

    Kumar, D. Ranjith; Ranjith, K. S.; Rajendrakumar, R. T.

    2015-06-24

    Samarium doped ZnO nanorods were grown on silicon substrate by using vapor phase transport method (VPT) with the growth temperature of 950°C. The synthesized nanorods were characterized by XRD, field emission scanning electron microscopy, Raman spectra, and photocurrent measurements. The XRD result revealed that Sm was successfully doped into lattice plane of hexagonal ZnO nanorods. The FESEM result confirms the pure ZnO has nanorod like morphology with an average diameter and length of 130nm and 10µm respectively. The above observation is supported by the Micro-Raman spectroscopy result. The photocurrent in the visible region has been significantly enhanced due to deposition of Sm on the surface of the ZnO nanorods. Sm acts as a visible sensitizer because of its lower band gap compared to ZnO.

  18. TUNING SILICON NANORODS FOR ANODES OF LI-ION RECHARGEABLE BATTERIES

    SciTech Connect

    Au, M.

    2010-11-23

    Silicon is a promising anode material for Li-ion batteries in regarding of high capacity, low cost and safety, but it suffers poor cycling stability due to the pulverization induced by severe volume expansion/shrinkage (297%) during lithium insertion/extraction. In our previous investigation on aluminum nanorods anodes, it is found the selection of substrates in which Al nanorods grown plays the role in prevention of pulverization resulting in the increase of cycling life. Adapting this knowledge, we investigated the Si based nanorods anodes by tuning its composition and element distribution. Our results show that although the Si nanorods demonstrated higher initial anodic capacity of 1500 mAh/g, it diminished after 50 cycles due to morphology change and pulverization. By codepositing Cu, the Si-Cu composite nanorods demonstrated sustainable capacity of 500 mAh/g in 100 cycles attributing to its flexible and less brittle nature.

  19. Surface-assisted unidirectional orientation of ZnO nanorods hybridized with nematic liquid crystals.

    PubMed

    Kubo, Shoichi; Taguchi, Rei; Hadano, Shingo; Narita, Mamiko; Watanabe, Osamu; Iyoda, Tomokazu; Nakagawa, Masaru

    2014-01-22

    Inorganic semiconductor nanorods are regarded as the primary components of optical and electrical nanoscale devices. In this paper, we demonstrate the unidirectional alignment of monolayered and dispersed ZnO nanorods on a rubbed polyimide alignment layer, which was achieved by a conventional liquid crystal alignment technique. The outermost surfaces of the ZnO nanorods (average diameter 7 nm; length 50 nm) were modified by polymerization initiator moieties, and nematic liquid crystalline (LC) methacrylate polymers were grown by atom transfer radical polymerization. By regulating the densities of the polymerization initiator moieties, we successfully hybridized LC-polymer-grafted ZnO nanorods and small nematic LC molecules. The LC-polymer-modified ZnO nanorods were hierarchically aligned on the substrate via cooperative molecular interactions among the liquid crystal mesogens, which induced molecular orientation on the rubbed polyimide alignment layer. PMID:24299205

  20. Photochemical synthesis of gold nanorods.

    PubMed

    Kim, Franklin; Song, Jae Hee; Yang, Peidong

    2002-12-01

    Gold nanorods have been synthesized by photochemically reducing gold ions within a micellar solution. The aspect ratio of the rods can be controlled with the addition of silver ions. This process reported here is highly promising for producing uniform nanorods, and more importantly it will be useful in resolving the growth mechanism of anisotropic metal nanoparticles due to its simplicity and the relatively slow growth rate of the nanorods. PMID:12452700

  1. A Study on the Physical Properties and Interfacial Reactions with Cu Substrate of Rapidly Solidified Sn-3.5Ag Lead-Free Solder

    NASA Astrophysics Data System (ADS)

    Ma, Hai-Tao; Wang, Jie; Qu, Lin; Zhao, Ning; Kunwar, A.

    2013-08-01

    A rapidly solidified Sn-3.5Ag eutectic alloy produced by the melt-spinning technique was used as a sample in this research to investigate the microstructure, thermal properties, solder wettability, and inhibitory effect of Ag3Sn on Cu6Sn5 intermetallic compound (IMC). In addition, an as-cast Sn-3.5Ag solder was prepared as a reference. Rapidly solidified and as-cast Sn-3.5Ag alloys of the same size were soldered at 250°C for 1 s to observe their instant melting characteristics and for 3 s with different cooling methods to study the inhibitory effect of Ag3Sn on Cu6Sn5 IMC. Experimental techniques such as scanning electron microscopy, differential scanning calorimetry, and energy-dispersive spectrometry were used to observe and analyze the results of the study. It was found that rapidly solidified Sn-3.5Ag solder has more uniform microstructure, better wettability, and higher melting rate as compared with the as-cast material; Ag3Sn nanoparticles that formed in the rapidly solidified Sn-3.5Ag solder inhibited the growth of Cu6Sn5 IMC during aging significantly much strongly than in the as-cast material because their number in the rapidly solidified Sn-3.5Ag solder was greater than in the as-cast material with the same soldering process before aging. Among the various alternative lead-free solders, this study focused on comparison between rapidly solidified and as-cast solder alloys, with the former being observed to have better properties.

  2. Surface Engineered Doping of Hematite Nanorod Arrays for Improved Photoelectrochemical Water Splitting

    PubMed Central

    Shen, Shaohua; Zhou, Jigang; Dong, Chung-Li; Hu, Yongfeng; Tseng, Eric Nestor; Guo, Penghui; Guo, Liejin; Mao, Samuel S.

    2014-01-01

    Given the narrow band gap enabling excellent optical absorption, increased charge carrier density and accelerated surface oxidation reaction kinetics become the key points for improved photoelectrochemical performances for water splitting over hematite (α-Fe2O3) photoanodes. In this study, a facile and inexpensive method was demonstrated to develop core/shell structured α-Fe2O3 nanorod arrays. A thin, Ag-doped overlayer of ~2–3 nm thickness was formed along α-Fe2O3 nanorods via ultrasonication treatment of solution-based β-FeOOH nanorods in Ag precursor solution followed by high temperature annealing. The obtained α-Fe2O3/AgxFe2−xO3 core/shell nanorod films demonstrated much higher photoelectrochemical performances as photoanodes than the pristine α-Fe2O3 nanorod film, especially in the visible light region; the incident photon-to-current efficiency (IPCE) at 400 nm was increased from 2.2% to 8.4% at 1.23 V vs. RHE (Reversible hydrogen electrode). Mott-Schottky analysis and X-ray absorption spectra revealed that the Ag-doped overlayer not only increased the carrier density in the near-surface region but also accelerated the surface oxidation reaction kinetics, synergistically contributing to the improved photoelectrochemical performances. These findings provide guidance for the design and optimization of nanostructured photoelectrodes for efficient solar water splitting. PMID:25316219

  3. Gold nanorod-templated synthesis of polymetallic hollow nanostructures with enhanced electrocatalytic performance.

    PubMed

    Guo, Xia; Ye, Wei; Zhu, Rui; Wang, Wenxin; Xie, Fang; Sun, Hongyan; Zhao, Qing; Ding, Yi; Yang, Jian

    2014-10-21

    Anisotropic polymetallic hollow nanostructures are highly desired for many applications because of their unique morphology, large specific surface areas and attractive electronic effects. Here, a simple method using gold nanorods as a self-sacrificed template has been developed for the fabrication of hollow dumbbell-like nanorods of Au@PtAg. The formation of the hollow structures involves the growth of another metallic shell first, and then the etching of gold nanorods, which is induced by oxygen and ascorbic acid. The lattice mismatch and cohesive energy of the shell, along with its surface passivation, greatly affect the subsequent etching and the resulting products, as has been demonstrated by a positive control in the case of Rh and a negative control in the case of Pd. Hollow dumbbell-like nanorods of Au@PtAg show great enhancement for the dehydrogenation pathway in the oxidation of formic acid, as compared to solid Au@PtAg nanorods, PtAu nanotubes and commercial Pt/C. PMID:25155233

  4. Efficient nanorod-based amorphous silicon solar cells with advanced light trapping

    NASA Astrophysics Data System (ADS)

    Kuang, Y.; van Lare, M. C.; Veldhuizen, L. W.; Polman, A.; Rath, J. K.; Schropp, R. E. I.

    2015-11-01

    We present a simple, low-cost, and scalable approach for the fabrication of efficient nanorod-based solar cells. Templates with arrays of self-assembled ZnO nanorods with tunable morphology are synthesized by chemical bath deposition using a low process temperature at 80 °C. The nanorod templates are conformally coated with hydrogenated amorphous silicon light absorber layers of 100 nm and 200 nm thickness. An initial efficiency of up to 9.0% is achieved for the optimized design. External quantum efficiency measurements on the nanorod cells show a substantial photocurrent enhancement both in the red and the blue parts of the solar spectrum. Key insights in the light trapping mechanisms in these arrays are obtained via a combination of three-dimensional finite-difference time-domain simulations, optical absorption, and external quantum efficiency measurements. Front surface patterns enhance the light incoupling in the blue, while rear side patterns lead to enhanced light trapping in the red. The red response in the nanorod cells is limited by absorption in the patterned Ag back contact. With these findings, we develop and experimentally realize a further advanced design with patterned front and back sides while keeping the Ag reflector flat, showing significantly enhanced scattering from the back reflector with reduced parasitic absorption in the Ag and thus higher photocurrent generation. Many of the findings in this work can serve to provide insights for further optimization of nanostructures for thin-film solar cells in a broad range of materials.

  5. A new silver nanorod SPR probe for detection of trace benzoyl peroxide

    PubMed Central

    Jiang, Zhiliang; Wen, Guiqing; Luo, Yanghe; Zhang, Xinghui; Liu, Qingye; Liang, Aihui

    2014-01-01

    The stable silver nanorod (AgNR) sol in red was prepared by the two-step procedure of NaBH4-H2O2 and citrate heating reduction. The AgNR had a transverse and a longitudinal surface plasmon resonance (SPR) absorption peak at 338 nm and 480 nm. Meanwhile, two transverse and longitudinal SPR Rayleigh scattering (SPR-RS) peaks at 340 nm and 500 nm were observed firstly using common fluorescence spectrometer. The SPR absorption, RS, surface enhanced Raman scattering (SERS) and electron microscope technology were used to study the formation mechanism of red silver nanorods and the SERS enhancement mechanism of nano-aggregation. The AgNR-BPO SPR absorption and AgNR-NaCl-BPO SPR-RS analytical systems were studied to develop two new simple, rapid, and low-cost SPR methods for the detection of trace BPO. PMID:24937042

  6. Photoelectrochemical and photosensing behaviors of hydrothermally grown ZnO nanorods

    SciTech Connect

    Majumder, T.; Hmar, J. J. L.; Roy, J. N.; Mondal, S. P. E-mail: suvra.phy@nita.ac.in; Debnath, K.; Gogurla, N.; Ray, S. K.

    2014-07-21

    ZnO nanorods have been grown on indium-tin-oxide coated glass substrates by a low cost chemical process. Current-voltage characteristics have been studied using ZnO nanorods as photoanode in an electrochemical cell. The flat band voltage shift and depletion width of ZnO nanorods/electrolyte interface have been estimated from Mott-Schottky (MS) characteristics. The electrochemical impedance measurements have been carried out to study the charge transport mechanism at the semiconductor-electrolyte interface under dark and white light (100 mW/cm{sup 2}) illumination. The doping concentration of nanorods has been extracted from MS plot. Photoresponse behavior of ZnO nanorods is found to be enhanced than seed layers with the incident of white light. Spectral dependent photovoltage of ZnO nanorods has been carried out using monochromatic light of wavelength 250–600 nm. The photopotential recovery time has been estimated for nanorods and seed layers. The stability of ZnO nanorods as a photoanode has been investigated.

  7. Functionalized zinc oxide nanorod with ionophore-membrane coating as an intracellular Ca2+ selective sensor

    NASA Astrophysics Data System (ADS)

    Asif, M. H.; Fulati, A.; Nur, O.; Willander, M.; Brännmark, Cecilia; Strâlfors, Peter; Börjesson, Sara I.; Elinder, Fredrik

    2009-07-01

    The tip of a borosilicate glass capillary with functionalized hexagonal ZnO nanorods was used to make a sensitive electrochemical intracellular Ca2+ sensor. To adjust the sensor for Ca2+ measurements with sufficient selectivity and stability, polyvinylchloride membrane containing Ca2+ ionophores were coated on the surface. The membrane covered ZnO nanorods exhibited a Ca2+-dependent electrochemical potential difference versus an Ag/AgCl reference electrode. The potential difference was linear over a large concentration range (100 nM-10 mM). The measurements of Ca2+ concentrations using our ZnO nanorods sensor in human fat cells or in frog egg cells were consistent with values of Ca2+ concentrations reported in the literature. This nanoelectrode device paves the way to measurements of intracellular biochemical species in specific locations within single living cells.

  8. Effect of Zinc Nitrate Concentration on the Optical and Morphological Properties of ZnO Nanorods for Photovoltaic Applications.

    PubMed

    Kim, Sung Jae; Anwar, M S; Heo, Si-Nae; Koo, Bon Heun

    2016-06-01

    We report the effect of zinc nitrate (ZN) concentration on the growth of zinc oxide (ZnO) nanorods and their optical and morphological properties. As prepared ZnO nanorods on glass substrate were characterized using field emission scanning electron microscopy (FE-SEM), ultra violet-visible (UV-Vis), Raman and Photo-luminescence (PL) spectroscopy. FE-SEM results show that the nanorods were obtained for the 0.033 and 0.053 M concentration of ZN. As the ZN concentration increased from 0.033 M to 0.053 M, the diameter of the nanorods was increased. It indicated that the diameter of the nanorods was affected by the ZN concentration. The Raman spectra of nanorods show only one peak at 438 cm(-1) corresponding to E2(high) high mode, which means that ZnO nanorods grown perpendicularly on the glass substrate, i.e., the ZnO nanorod arrays are highly c-axis oriented. Room-temperature PL spectrum of the as-grown ZnO nanorods reveals a near-band-edge (NBE) emission peak and defect induced green light emission. The green light emission band at -579 nm might be attributed to surface oxygen vacancies or defects. The UV-visible measurements reflect that the total transmittance for the as grown ZnO nanorods is over 80%. The simple technique presented in this study to grow ZnO nanorods on a glass substrate can be helpful for making the cost effective photovoltaic devices. PMID:27427680

  9. Preparation and characterization of one-dimensional GaN nanorods with Tb intermediate layer

    SciTech Connect

    Shi, Feng; Xue, Chengshan

    2012-12-15

    Graphical abstract: Display Omitted Highlights: ► GaN nanorods have been prepared on Si substrates by magnetron sputtering. ► GaN nanorods are single crystal with hexagonal wurtzite structure. ► GaN nanorods are high-quality crystalline after ammoniating at 950 °C for 15 min. ► Ammoniating temperatures and times affect the growth of GaN nanorods significantly. -- Abstract: GaN nanorods have been successfully prepared on Si(1 1 1) substrates by magnetron sputtering through ammoniating Ga{sub 2}O{sub 3}/Tb thin films. X-ray diffraction (XRD), X-ray photoelectron spectroscope (XPS), FT-IR spectrophotometer, scanning electron microscope (SEM), high-resolution transmission electron microscope (HRTEM), and photoluminescence (PL) spectroscopy were used to characterize the microstructures, morphologies compositions and optical properties of the GaN samples. The results demonstrate that the nanorods are single crystal GaN with hexagonal wurtzite structure and high-quality crystalline after ammoniating at 950 °C for 15 min, which have the size of 100–150 nm in diameter. Ammoniating temperatures and times affect the growth of GaN nanorods significantly. The growth procedure mainly follows the Tb catalyst-assisted VLS mechanism.

  10. Domain structure of tetragonal Pb(Zr,Ti)O3 nanorods and its size dependence

    NASA Astrophysics Data System (ADS)

    Yamada, Tomoaki; Ito, Daisuke; Sakata, Osami; Kuroishi, Junki; Namazu, Takahiro; Imai, Yasuhiko; Shiraishi, Takahisa; Shimizu, Takao; Funakubo, Hiroshi; Yoshino, Masahito; Nagasaki, Takanori

    2015-10-01

    We fabricated {100} Pb(Zr0.35Ti0.65)O3 (PZT) nanorods by partly etching a film grown on a Nb-doped SrTiO3 substrate using a focused ion beam, followed by annealing to recover the etching damage and promote the formation of a stable domain structure in the form of nanorods. The application of synchrotron micro-X-ray diffraction enabled the detection of the diffraction intensity from a single nanorod, which allowed us to clarify the size dependence of the domain structure of the fabricated nanorods. We found that the a-domain fraction in the tetragonal PZT nanorods decreased with decreasing rod width and that an exclusively c-domain structure was formed in nanorods of ≤1 µm width. The preferred formation of the c-domain in these nanorods can be rationalized in terms of the large depolarizing field in the a-domain and/or the in-plane compressive strain near the PZT/substrate interface.

  11. A structural investigation of highly ordered catalyst- and mask-free GaN nanorods.

    PubMed

    Figge, S; Aschenbrenner, T; Kruse, C; Kunert, G; Schowalter, M; Rosenauer, A; Hommel, D

    2011-01-14

    GaN nanorods were grown on r-plane sapphire substrates by a two-step approach. Nucleation sites for the nanorods were provided by the formation of AlN islands during nitridation in a metal organic vapor phase system. These islands are a-plane oriented as expected for nitride growth on r-plane sapphire. The nanorods themselves were grown by plasma assisted molecular beam epitaxy. The nanorods show an inclination towards the surface normal of 28.3° and are highly ordered. Studies with high resolution x-ray diffraction polar plots reveal the epitaxial relationship between the substrate and nanorods as a c-direction growth on inclined m-plane facets of the nitridated islands. The determined lattice constants show nanorods which are strain free. The growth direction of the nanorods has been confirmed in a transmission electron microscope by convergent beam electron diffraction patterns to be in the N-polar [Formula: see text] direction. PMID:21139192

  12. Piezoelectric nanogenerator based on zinc oxide nanorods grown on textile cotton fabric

    NASA Astrophysics Data System (ADS)

    Khan, Azam; Ali Abbasi, Mazhar; Hussain, Mushtaque; Hussain Ibupoto, Zafar; Wissting, Jonas; Nur, Omer; Willander, Magnus

    2012-11-01

    This investigation explores piezoelectricity generation from ZnO nanorods, which were grown on silver coated textile cotton fabrics using the low temperature aqueous chemical growth method. The morphology and crystal structure studies were carried out by x-ray diffraction, scanning electron microscopic and high resolution transmission electron microscopic techniques, respectively. ZnO nanorods were highly dense, well aligned, uniform in spatial distribution and exhibited good crystal quality. The generation of piezoelectricity from fabricated ZnO nanorods grown on textile cotton fabrics was measured using contact mode atomic force microscopy. The average output voltage generated from ZnO nanorods was measured to be around 9.5 mV. This investigation is an important achievement regarding the piezoelectricity generation on textile cotton fabric substrate. The fabrication of this device provides an alternative approach for a flexible substrate to develop devices for energy harvesting and optoelectronic technology on textiles.

  13. Photovoltaic properties of ZnO nanorods/p-type Si heterojunction structures.

    PubMed

    Pietruszka, Rafal; Witkowski, Bartlomiej Slawomir; Luka, Grzegorz; Wachnicki, Lukasz; Gieraltowska, Sylwia; Kopalko, Krzysztof; Zielony, Eunika; Bieganski, Piotr; Placzek-Popko, Ewa; Godlewski, Marek

    2014-01-01

    Selected properties of photovoltaic (PV) structures based on n-type zinc oxide nanorods grown by a low temperature hydrothermal method on p-type silicon substrates (100) are investigated. PV structures were covered with thin films of Al doped ZnO grown by atomic layer deposition acting as transparent electrodes. The investigated PV structures differ in terms of the shapes and densities of their nanorods. The best response is observed for the structure containing closely-spaced nanorods, which show light conversion efficiency of 3.6%. PMID:24605282

  14. Microwave assisted hydrothermal synthesize of ZnO nanorods and their characterization

    NASA Astrophysics Data System (ADS)

    Shojaee, Nadi; Ebadzadeh, Touradj; Aghaei, Alireza

    In present study ZnO nanorods were synthesized in an aqueous solution using a domestic microwave oven for irradiation. The nanorods have been grown on substrates immersed in an aqueous solution which contains zinc nitrate and hexamethylenetetramine as precursors. Eventually, effect of some parameters such as precursor's concentration and heating time on growth mechanism was characterized. The product phase was detected using X-ray diffraction (XRD). Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) exhibited the resultant structure is uniform and single crystalline. Finally Uv-Vis spectroscopy was used to measure the nanorod's band gap.

  15. The use of silver nanorod array based surface enhanced Raman scattering sensor for food safety applications

    Technology Transfer Automated Retrieval System (TEKTRAN)

    For the advancement of preventive strategies, it is critical to develop rapid and sensitive detection methods with nanotechnology for food safety applications. This article reports the recent development on the use of aligned silver nanorod (AgNR) arrays prepared by oblique angle deposition, as surf...

  16. BULK SYNTHESIS OF SILVER NANORODS IN POLY(ETHYLENE GLYCOL) USING MICROWAVE IRRADIATION

    EPA Science Inventory

    Microwave-assisted (MW), surfactantless, greener approach to bulk synthesis of silver nanorods employing poly (ethylene glycol) (PEG) is described. An aqueous solution of silver nitrate (AgNO-3,- 0.1 M, 4 mL) and 4 mL of PEG (molecular weight 300) were mixed at room temperature t...

  17. Evaporative Self-Assembly of Gold Nanorods into Macroscopic 3D Plasmonic Superlattice Arrays.

    PubMed

    Li, Penghui; Li, Yong; Zhou, Zhang-Kai; Tang, Siying; Yu, Xue-Feng; Xiao, Shu; Wu, Zhongzhen; Xiao, Quanlan; Zhao, Yuetao; Wang, Huaiyu; Chu, Paul K

    2016-04-01

    Millimeter-scale 3D superlattice arrays composed of dense, regular, and vertically aligned gold nanorods are fabricated by evaporative self-assembly. The regular organization of the gold nanorods into a macroscopic superlattice enables the production of a plasmonic substrate with excellent sensitivity and reproducibility, as well as reliability in surface-enhanced Raman scattering. The work bridges the gap between nanoscale materials and macroscopic applications. PMID:26823278

  18. Structural evolution of gold nanorods during controlled secondary growth.

    PubMed

    Keul, Heidrun A; Möller, Martin; Bockstaller, Michael R

    2007-09-25

    Single-crystalline gold nanorods synthesized by the Ag(I)-mediated seeded-growth method (see: El-Sayed, M. A.; Nikoobakht, B. Chem. Mater. 2003, 15, 1957) were used as seeds for the preferential overgrowth of gold on particular crystallographic facets by systematic variation of the conditions during overgrowth. The results support previous reports about the relevance of the cationic surfactant cetyltrimethylammonium bromide (CTAB) and Ag(I) in stabilizing anisotropic particle shapes and demonstrate that the regulation of the amount of ascorbic acid facilitates the preferential overgrowth of {111} crystal facets to form Xi-type particle shapes. Interestingly, secondary overgrowth is found to inevitably result in a loss of particle shape anisotropy. A mechanism based on surface reconstruction is proposed to rationalize the "shape-reversal" that is generally observed in the nanorod growth process, that is, the initial increase and subsequent decrease of particle anisotropy with increasing reaction time. High-resolution electron microscopy analysis of gold nanorods reveals clear evidence for (1 x 2) missing row surface reconstruction of high energetic {110} facets that form during the initial phase during particle growth. PMID:17713936

  19. Micro-Structural Properties of YBa2Cu3O(7-x)/ZnO Nanorods on SrTiO3.

    PubMed

    Jin, Zhenlan; Park, Changin; Song, Kyu Jeong; Kang, Sukil; Ko, Kyeong-Eun; Park, Chan; Ko, Rock Kil; Han, S W

    2015-01-01

    We examined the local structural and the interfacial properties of YBa2Cu3O(7-x) (YBCO)/ZnO nanorods on SrTiO3 (STO) substrates using various measurements. Vertically aligned ZnO nanorods were synthesized on STO substrates using a catalyst-free metal-organic chemical vapor deposition. YBCO films were deposited ex-situ on the ZnO nanorods/STO templates using a DC magnetron sputtering deposition. X-ray diffraction revealed that the YBCO films were crystallized along their c-axes on the ZnO nanorods/STO templates. Transmission electron microscopy measurements demonstrated that YBCO filled the space between ZnO nanorods and that both interfaces of YBCO/ZnO nanorods and ZnO nanorods/STO were quite clean with no disorder. Polarization-dependent extended X-ray absorption fine structure measurements at the Cu K edge showed extra disorder in the CuO2 planes of YBCO/ZnO nanorods/STO, compared with that of YBCO/STO. The superconductivity transition temperature (T(c)) of YBCO/ZnO nanorods/STO was approximately 50 K whereas that of YBCO/STO was 93 K. The decrease of T(c) of YBCO/ZnO nanorods/STO was ascribed to the structural disorder of CuO2 planes as well as grain boundaries in the YBCO films. PMID:26328417

  20. Surface electrochemical properties of niobium-doped titanium dioxide nanorods and their effect on carrier collection efficiency of dye sensitized solar cells

    NASA Astrophysics Data System (ADS)

    Yang, Mengjin; Ding, Bo; Lee, Jung-Kun

    2014-01-01

    We explore the effect of Nb-doping on the electronic band structure and microstructure of 1-dimensional rutile TiO2 nanorods as a photoanode of dye sensitized solar cells (DSSCs). The nanorods with different Nb concentration are directly grown on top of fluorine doped tin oxide (FTO) substrates and then assembled into DSSCs. Nb-doping is found to greatly enhance the energy conversion efficiency of nanorod-based DSSCs by more than 70%. This improvement in the photon-electron conversion process is attributed to enhanced electron injection and suppressed carrier recombination at the dye-nanorod interface and at the nanorod-FTO interface. Flat band potential analysis shows that Nb-doping shifts the surface potential of the nanorods positively to promote electron injection from the dye sensitizers to the nanorods. In addition, the nanoscale conductive atomic force microscopy (c-AFM) measurement of individual nanorods shows that the high carrier concentration of the Nb-doped nanorods facilitates electron tunneling at the nanorod-FTO interface. New observations in this study indicate that Nb-doping into the nanorods modifies their surface states and the interface resistance between TiO2 and FTO. This facilitates the carrier transport from the excited dye to the FTO film by suppressing carrier recombination and improving electron collection efficiency.

  1. Hydrothermal synthesis of highly crystalline ZnO nanorod arrays: Dependence of morphology and alignment on growth conditions

    NASA Astrophysics Data System (ADS)

    Azzez, Shrook A.; Hassan, Z.; Hassan, J. J.; Alimanesh, M.; Rasheed, Hiba S.; Sabah, Fayroz A.; Abdulateef, Sinan A.

    2016-07-01

    Highly oriented zinc oxide nanorod were successfully grown on seeded p-type silicone substrate by hydrothermal methode. The morphology and the crystallinty of ZnO c-axis (002) arrays were systematically studied using field emission scanning electron microscopy (FESEM) and X-ray diffraction (XRD) methods. The effect of seed layer pre-annealing on nanorods properties was explained according to the nucleation site of ZnO nanoparticles on silicon substrate. In addition, the variation of the equal molarity of zinc nitrate hexahydrate and hexamine concentrations in the reaction vessel play a crucial role related to the ZnO nanorods.

  2. Attachment of Quantum Dots on Zinc Oxide Nanorods

    NASA Astrophysics Data System (ADS)

    Seay, Jared; Liang, Huan; Harikumar, Parameswar

    2011-03-01

    ZnO nanorods grown by hydrothermal technique are of great interest for potential applications in photovoltaic and optoelectronic devices. In this study we investigate the optimization of the optical absorption properties by a low temperature, chemical bath deposition technique. Our group fabricated nanorods on indium tin oxide (ITO) substrate with precursor solution of zinc nitrate hexahydrate and hexamethylenetramine (1:1 molar ratio) at 95C for 9 hours. In order to optimize the light absorption characteristics of ZnO nanorods, CdSe/ZnS core-shell quantum dots (QDs) of various diameters were attached to the surface of ZnO nanostructures grown on ITO and gold-coated silicon substrates. Density of quantum dots was varied by controlling the number drops on the surface of the ZnO nanorods. For a 0.1 M concentration of QDs of 10 nm diameter, the PL intensity at 385 nm increased as the density of the quantum dots on ZnO nanostructures was increased. For quantum dots at 1 M concentration, the PL intensity at 385 nm increased at the beginning and then decreased at higher density. We will discuss the observed changes in PL intensity with QD concentration with ZnO-QD band structure and recombination-diffusion processes taking place at the interface.

  3. Facet control of gold nanorods

    DOE PAGESBeta

    Zhang, Qingfeng; Han, Lili; Jing, Hao; Blom, Douglas A.; Lin, Ye; Xin, Huolin L.; Wang, Hui

    2016-01-21

    While great success has been achieved in fine-tuning the aspect ratios and thereby the plasmon resonances of cylindrical Au nanorods, facet control with atomic level precision on the highly curved nanorod surfaces has long been a significantly more challenging task. The intrinsic structural complexity and lack of precise facet control of the nanorod surfaces remain the major obstacles for the atomic-level elucidation of the structure–property relationships that underpin the intriguing catalytic performance of Au nanorods. Here we demonstrate that the facets of single-crystalline Au nanorods can be precisely tailored using cuprous ions and cetyltrimethylammonium bromide as a unique pair ofmore » surface capping competitors to guide the particle geometry evolution during nanorod overgrowth. By deliberately maneuvering the competition between cuprous ions and cetyltrimethylammonium bromide, we have been able to create, in a highly controllable and selective manner, an entire family of nanorod-derived anisotropic multifaceted geometries whose surfaces are enclosed by specific types of well-defined high-index and low-index facets. This facet-controlled nanorod overgrowth approach also allows us to fine-tune the particle aspect ratios while well-preserving all the characteristic facets and geometric features of the faceted Au nanorods. Furthermore, taking full advantage of the combined structural and plasmonic tunability, we have further studied the facet-dependent heterogeneous catalysis on well-faceted Au nanorods using surface-enhanced Raman spectroscopy as an ultrasensitive spectroscopic tool with unique time-resolving and molecular finger-printing capabilities.« less

  4. Facet Control of Gold Nanorods.

    PubMed

    Zhang, Qingfeng; Han, Lili; Jing, Hao; Blom, Douglas A; Lin, Ye; Xin, Huolin L; Wang, Hui

    2016-02-23

    While great success has been achieved in fine-tuning the aspect ratios and thereby the plasmon resonances of cylindrical Au nanorods, facet control with atomic level precision on the highly curved nanorod surfaces has long been a significantly more challenging task. The intrinsic structural complexity and lack of precise facet control of the nanorod surfaces remain the major obstacles for the atomic-level elucidation of the structure-property relationships that underpin the intriguing catalytic performance of Au nanorods. Here we demonstrate that the facets of single-crystalline Au nanorods can be precisely tailored using cuprous ions and cetyltrimethylammonium bromide as a unique pair of surface capping competitors to guide the particle geometry evolution during nanorod overgrowth. By deliberately maneuvering the competition between cuprous ions and cetyltrimethylammonium bromide, we have been able to create, in a highly controllable and selective manner, an entire family of nanorod-derived anisotropic multifaceted geometries whose surfaces are enclosed by specific types of well-defined high-index and low-index facets. This facet-controlled nanorod overgrowth approach also allows us to fine-tune the particle aspect ratios while well-preserving all the characteristic facets and geometric features of the faceted Au nanorods. Taking full advantage of the combined structural and plasmonic tunability, we have further studied the facet-dependent heterogeneous catalysis on well-faceted Au nanorods using surface-enhanced Raman spectroscopy as an ultrasensitive spectroscopic tool with unique time-resolving and molecular finger-printing capabilities. PMID:26795706

  5. Effect of phosphorus incorporation on morphology and optical properties of ZnO nanorods

    SciTech Connect

    Fan, Donghua; Zhang, Rong; Wang, Xianghu

    2011-04-15

    Graphical abstract: XPS spectra of the P-doped ZnO nanorods: (a) Zn 2p, (b) O 1s, and (c) P 2p spectra. The red curve in c is the Gauss-fitting curve. (d) Raman spectra of P-doped (curve 1) and pure (curve 2) ZnO nanorods. Research highlights: {yields} P-doped ZnO nanorods have been prepared on Si substrates without any catalyst. {yields} The introduction of phosphorus leads to the growth of tapered tip in the nanorods. {yields} The formation of tapered tip is attributed to the relaxation of the lattice strain along the radial direction. {yields} The strong ultraviolet peak is connected with the phosphorus acceptor-related emissions. -- Abstract: Phosphorus-doped ZnO nanorods have been prepared on Si substrates by thermal evaporation process without any catalyst. X-ray photoelectron spectroscopy and Raman spectra indicate that phosphorus entering into ZnO nanorods mainly occupies Zn site rather than O one. The introduction of phosphorus leads to the morphological changes of nanorods from hexagonal tip to tapered one, which should be attributed to the relaxation of the lattice strain caused by phosphorus occupying Zn site along the radial direction. Transmission electron microscopy shows that phosphorus-doped ZnO nanorods still are single crystal and grow along [0 0 0 1] direction. The effect of phosphorous dopant on optical properties of ZnO nanorods also is studied by the temperature-dependent photoluminescence spectra, which indicates that the strong ultraviolet emission is connected with the phosphorus acceptor-related emissions.

  6. Angle-resolved reflectance of obliquely aligned silver nanorods.

    PubMed

    Wang, X J; Abell, J L; Zhao, Y-P; Zhang, Z M

    2012-04-01

    Arrays of silver nanorods (AgNRs) formed by oblique-angle deposition (OAD) are strongly anisotropic, with either metallic or dielectric characteristics depending on the polarization of incident light, and may be used to enhance Raman scattering and surface plasmon polaritons. This work investigates the polarization-dependent reflectance of inclined AgNR arrays at the wavelengths of 635 and 977 nm. The specular reflectance at various incidence angles and the bidirectional reflectance distribution function were measured with a laser scatterometer, while the directional-hemispherical reflectance was measured with an integrating sphere. The AgNR layer is modeled as an effectively homogenous, optically uniaxial material using the effective medium theory to elucidate the dielectric or metallic response for differently polarized incidence. The thin-film optics formulation is modified considering optical anisotropy and surface scattering. This study helps gain a better understanding of optical properties of nanostructured materials. PMID:22505070

  7. Growth and characterization of vertically aligned ZnO nanorods grown on porous silicon: Effect of precursor concentration

    NASA Astrophysics Data System (ADS)

    Shabannia, R.; Abu Hassan, H.

    2013-10-01

    Vertically aligned ZnO nanorods were successfully synthesized on porous silicon (PS) substrates by chemical bath deposition method at low temperature. The effect of precursor concentration on the growth of ZnO nanorods were systematically characterized by X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), low and high-resolution transmission electron microscopy (HRTEM), photoluminescence (PL), and Raman spectroscopy. The XRD results reveal that all the as-grown ZnO nanorod arrays grew preferentially oriented along the c-axis with a hexagonal wurtzite structure. The FESEM images show that the ZnO nanorods grown perpendicular to the PS substrates had diameters and lengths ranging from 13 nm to 69 nm and from 85 nm to 208 nm, respectively. The low-resolution TEM image indicates that the ZnO nanorod arrays had a uniform diameter along their whole length and a smooth surface. PL and Raman analyses reveal that the aligned ZnO nanorods exhibited a sharp ultraviolet peak and high E2 (high) at around 390 nm and 433.8 cm-1, respectively. Furthermore, the ZnO nanorods grew vertically under 0.050 M precursor concentration, resulting in a high structural and optical quality. These ZnO nanorods can be potentially used for fabricating nanoelectronic and nano-optical devices.

  8. Semiconductor nanorod liquid crystals

    SciTech Connect

    Li, Liang-shi; Walda, Joost; Manna, Liberato; Alivisatos, A. Paul

    2002-01-28

    Rodlike molecules form liquid crystalline phases with orientational order and positional disorder. The great majority of materials in which liquid crystalline phases have been observed are comprised of organic molecules or polymers, even though there has been continuing and growing interest in inorganic liquid crystals. Recent advances in the control of the sizes and shapes of inorganic nanocrystals allow for the formation of a broad class of new inorganic liquid crystals. Here we show the formation of liquid crystalline phases of CdSe semiconductor nanorods. These new liquid crystalline phases may have great importance for both application and fundamental study.

  9. Enhanced Raman scattering and photocatalytic activity of Ag/ZnO heterojunction nanocrystals.

    PubMed

    Chen, Chongqi; Zheng, Yuanhui; Zhan, Yingying; Lin, Xingyi; Zheng, Qi; Wei, Kemei

    2011-10-01

    In this work, we study the enhancement of Raman signals and photocatalytic activity of Ag/ZnO heterojunctions with an Ag content of 1 at.%, which were synthesized by photochemical deposition of Ag nanoparticles onto pre-synthesized ZnO nanorods. A strong interaction between Ag and ZnO nanocrystals were evidenced by XPS and UV-vis spectroscopy. The binding energy of Ag nanoparticles shifts toward lower energy compared to that of pure Ag nanoparticles, revealing that electrons transfer from Ag to the ZnO nanocrystals. The red shift of the plasmon absorption peak of Ag nanoparticles in Ag/ZnO heterojunctions further confirms the strong interaction between the two components. This strong interaction, arising from the coupling between Ag and ZnO nanocrystals, is responsible for the enhancement of Raman signals and photocatalytic activity of the Ag/ZnO heterojunctions. PMID:21847472

  10. A double signal electrochemical human immunoglobulin G immunosensor based on gold nanoparticles-polydopamine functionalized reduced graphene oxide as a sensor platform and AgNPs/carbon nanocomposite as signal probe and catalytic substrate.

    PubMed

    Zhang, Si; Huang, Na; Lu, Qiujun; Liu, Meiling; Li, Haitao; Zhang, Youyu; Yao, Shouzhuo

    2016-03-15

    In this paper, a double signal electrochemical Human immunoglobulin G (HIgG) immunosensor based on AgNPs/carbon nanocomposite (Ag/C NC) as the signal probe and catalytic substrate was developed for fast and sensitive detection of HIgG. The as-prepared AuNPs-PDA-rGO nanocomposite and Ag/C NC were confirmed by UV-vis, Fourier transform infrared spectroscopy, scanning electron microscopy and transmission electron microscopy. Electrochemical impedance spectroscopy, cyclic voltammetry and differential pulse voltammetry were used to investigate the electrochemical properties of the proposed immunosensor. The AuNPs-PDA-rGO nanocomposite can improve the electron transfer rate and capture more Ab1. In the sandwich-type immunoassay process, the Ag/C NC functionalized bioconjugates were captured on HIgG/Ab1/AuNPs-PDA-rGO surface and the electrochemical double-signal strategy was employed. These double electrochemical detection signals were directly monitored the oxidation current originated from Ag/C NC and indirectly detected the reduction current of benzoquinone which was produced from the reaction of H2O2 and HQ by catalysis of Ag/C NC in electrochemical detection of HIgG. Under the optimized conditions, the current responses were changed with the concentrations of HIgG for the proposed immunosensor with wide linear ranges of 0.1 to 100 ngmL(-1) and 0.01-100 ngmL(-1) with the lowest detection concentration of 0.001 ng mL(-1) in the absence and presence of H2O2 and HQ. The double-signal strategy is used for detection of HIgG, and the results came from the two signals were well consistent with each other. The proposed immunosensor was successfully applied in analysis of human IgG in real samples and this strategy may provide a relative simple and effective method for construction of other immunsensors in detection of other biomarkers in clinical medicine. PMID:26556185

  11. Thioxanthone functionalized silver nanorods as smart photoinitiating assemblies to generate photopolymer/metal nano-objects.

    PubMed

    Niu, Songlin; Schneider, Raphaël; Vidal, Loïc; Balan, Lavinia

    2013-07-21

    Silver nanorods (AgNRs) with lengths in the 50-60 nm range were synthesized and functionalized with 2-(2-mercaptoethyl)thioxanthone (C2TX) to generate AgNR@C2TX nanoassemblies. When irradiated at 377 nm in the presence of a diacrylate monomer, these dispersed nanoassemblies initiate radical photopolymerization, indicating that the excited singlet to triplet intersystem crossing process of C2TX in the vicinity of AgNRs was favored while the fluorescence of C2TX was completely quenched at the surface of NRs. SEM and TEM images confirmed the formation of a AgNR-polymer nanocomposite and the homogeneous dispersion of AgNRs in the polymer film. Moreover, under specific experimental conditions allowing the spatial extent of the polymerization to be limited, polymer-capped AgNRs were obtained (polymer diameter of ca. 1 nm). PMID:23760523

  12. Wettability properties of PTFE/ZnO nanorods thin film exhibiting UV-resilient superhydrophobicity

    NASA Astrophysics Data System (ADS)

    Bayat, A.; Ebrahimi, M.; Nourmohammadi, A.; Moshfegh, A. Z.

    2015-06-01

    In this research, initially anodization process was used to fabricate ZnO nanorods on Zn substrate and then RF sputtering technique was applied to grow a thin layer of polytetrafluoroethylene (PTFE, Teflon) on the coated ZnO nanorods for producing a superhydrophobic surface. According to scanning electron microscopy (SEM) observations, ZnO nanorods were formed with average diameter and length of about ∼180 nm and 14 μm, respectively. Superhydrophilic property of ZnO nanorods and superhydrophobic property of PTFE/ZnO nanorods was investigated by water contact angle (WCA) measurements. It was found that the contact angle varied with the PTFE deposition time. The highest contact angle measurement was obtained at 160° for the PTFE (60 min coating)/ZnO as optimum sample which indicates its superhydrophobic property. X-ray photoelectron spectroscopy (XPS) determined surface chemical composition and F/C ratio of about 1.27 for this sample. A change of water contact angle from 3° to 160° indicates transition from superhydrophilic to superhydrophobic state. Very low contact angle hysteresis (CAH) of ∼2° and sliding angle (SA) of ∼1° as well as unchanged contact angle under UV illumination was observed for the synthesized optimum PTFE/ZnO sample exhibits an excellent superhydrophobic property. Based on our data analysis, the ZnO nanorods and the PTFE/ZnO nanorods obey Wenzel and Cassie-Baxter model, respectively.

  13. Direct growth of tellurium nanorod arrays on Pt/FTO/glass through a surfactant-assisted chemical reduction.

    PubMed

    Liu, Hongmei; Zeng, Boming; Jia, Falong

    2011-07-29

    Uniform tellurium nanorod arrays (TNA) have been successfully deposited directly on Pt/FTO (F-doped SnO(2))/glass substrate through a facile surfactant-assisted approach, which involved chemical reduction of TeO(3)(2-) ions by hydrazine hydrate. The whole synthesis process is highly repeatable and performed simply by immersing the Pt/FTO/glass in the solution for a certain time. During the growth of TNA, Pt catalyzed the reduction of TeO(3)(2-) ions by hydrazine hydrate and Te nanoparticles were deposited firmly on the substrate at first. Then, under the regulation of the surfactant (cetyltrimethylammonium bromide, CTAB), the deposited Te grew into nanorod arrays and adhered firmly to the substrate. Similar Te nanorod arrays could also grow on a Pd substrate which has the same catalytic performance as that of Pt. The as-synthesized TNA could be used as a good template to synthesize platinum-and gold-coated nanorods through convenient galvanic replacement. As a demonstration of potential application, the gold/tellurium nanorods showed uniform surface-enhanced Raman scattering (SERS) using rhodamine 6G (Rh6G) as the analyte. This approach provides a simple route for the growth of standing Te nanorods on a substrate, which may be used for the synthesis of other standing one-dimensional materials through a similar mechanism. PMID:21719969

  14. Direct growth of tellurium nanorod arrays on Pt/FTO/glass through a surfactant-assisted chemical reduction

    NASA Astrophysics Data System (ADS)

    Liu, Hongmei; Zeng, Boming; Jia, Falong

    2011-07-01

    Uniform tellurium nanorod arrays (TNA) have been successfully deposited directly on Pt/FTO (F-doped SnO2)/glass substrate through a facile surfactant-assisted approach, which involved chemical reduction of TeO32 - ions by hydrazine hydrate. The whole synthesis process is highly repeatable and performed simply by immersing the Pt/FTO/glass in the solution for a certain time. During the growth of TNA, Pt catalyzed the reduction of TeO32 - ions by hydrazine hydrate and Te nanoparticles were deposited firmly on the substrate at first. Then, under the regulation of the surfactant (cetyltrimethylammonium bromide, CTAB), the deposited Te grew into nanorod arrays and adhered firmly to the substrate. Similar Te nanorod arrays could also grow on a Pd substrate which has the same catalytic performance as that of Pt. The as-synthesized TNA could be used as a good template to synthesize platinum-and gold-coated nanorods through convenient galvanic replacement. As a demonstration of potential application, the gold/tellurium nanorods showed uniform surface-enhanced Raman scattering (SERS) using rhodamine 6G (Rh6G) as the analyte. This approach provides a simple route for the growth of standing Te nanorods on a substrate, which may be used for the synthesis of other standing one-dimensional materials through a similar mechanism.

  15. Label-free SERS study of galvanic replacement reaction on silver nanorod surface and its application to detect trace mercury ion

    PubMed Central

    Wang, Yaohui; Wen, Guiqing; Ye, Lingling; Liang, Aihui; Jiang, Zhiliang

    2016-01-01

    It is significant to explore a rapid and highly sensitive galvanic replacement reaction (GRR) surface enhanced Raman scattering (SERS) method for detection of trace mercury ions. This article was reported a new GRR SERS analytical platform for detecting Hg(II) with label-free molecular probe Victoria blue B (VBB). In HAc-NaCl-silver nanorod (AgNR) substrate, the molecular probe VBB exhibited a strong SERS peak at 1609 cm−1. Upon addition of Hg(II), the GRR occurred between the AgNR and Hg(II), and formed a weak SERS activity of Hg2Cl2 that deposited on the AgNR surfaces to decrease the SERS intensity at 1609 cm−1. The decreased SERS intensity was linear to Hg(II) concentration in the range of 1.25–125 nmol/L, with a detection limit of 0.2 nmol/L. The GRR was studied by SERS, transmission electron microscopy and other techniques, and the GRR mechanism was discussed. PMID:26792071

  16. Fabrication of ZnO nanorod using spray-pyrolysis and chemical bath deposition method

    SciTech Connect

    Ramadhani, Muhammad F. Pasaribu, Maruli A. H. Yuliarto, Brian Nugraha

    2014-02-24

    ZnO thin films with nanorod structure were deposited using Ultrasonic Spray Pyrolysis method for seed growth, and Chemical Bath Deposition (CBD) for nanorod growth. High purity Zn-hydrate and Urea are used to control Ph were dissolved in ethanol and aqua bidest in Ultrasonic Spray Pyrolysis process. Glass substrate was placed above the heater plate of reaction chamber, and subsequently sprayed with the range duration of 5, 10 and 20 minutes at the temperatures of 3500 C. As for the Chemical Bath Deposition, the glass substrate with ZnO seed on the surface was immerse to Zn-hydrate, HMTA (Hexa Methylene Tetra Amine) and deionized water solution for duration of 3, 5 and 7 hour and temperatures of 600 C, washed in distilled water, dried, and annealed at 3500 C for an hour. The characterization of samples was carried out to reveal the surface morphology using Scanning Electron Microscopy (SEM). From the data, the combination of 5 minutes of Ultrasonic Spray Pyrolysis process and 3 hour of CBD has showed the best structure of nanorod. Meanwhile the longer Spraying process and CBD yield the bigger nanorod structure that have been made, and it makes the films more dense which make the nanorod collide each other and as a result produce unsymetric nanorod structure.

  17. Hydrothermal growth and characterization of vertically well-aligned and dense ZnO nanorods on glass and silicon using a simple optimizer system

    NASA Astrophysics Data System (ADS)

    Mohammad, Sabah M.; Hassan, Z.; Ahmed, Naser M.; Talib, Rawnaq A.; Abd-Alghafour, Nabeel M.; Omar, A. F.

    2016-07-01

    Vertically, well-aligned and high density ZnO nanorods were successfully hydrothermally grown on glass and silicon substrates using a simple and low cost system. The mechanism of synthesis of ZnO nanorods, generated with our system under hydrothermal conditions, is investigated in this report. Field-emission scanning electron microscopy indicated that the fabricated ZnO nanorods on both substrates have hexagonal shape with diameters ranging from 20 nm to 70 nm which grew vertically from the substrate. XRD analysis confirms the formation of wurtzite ZnO phase with a preferred orientation along (002) direction perpendicular on the substrate and enhanced crystallinity. The low value of the tensile strain (0.126 %) revealed that ZnO nanorods preferred to grow along the c-axis for both substrates. Photoluminescence spectra exhibited a strong, sharp UV near band edge emission peak with narrow FWHM values for both samples.

  18. Horizontally assembled green InGaN nanorod LEDs: scalable polarized surface emitting LEDs using electric-field assisted assembly

    PubMed Central

    Park, Hoo Keun; Yoon, Seong Woong; Eo, Yun Jae; Chung, Won Woo; Yoo, Gang Yeol; Oh, Ji Hye; Lee, Keyong Nam; Kim, Woong; Do, Young Rag

    2016-01-01

    In this study, we report the concerted fabrication process, which is easy to transform the size of active emitting area and produce polarized surface light, using the electric-field-assisted assembly for horizontally assembled many tiny nanorod LEDs between two metal electrodes. We fabricate the millions of individually separated 1D nanorod LEDs from 2D nanorod arrays using nanosphere lithography, etching and cutting process of InGaN/GaN LED structure on a flat sapphire substrate. The horizontally assembled InGaN-based nanorods LED device shows bright (~2,130 cd/m2) and uniform polarized (polarization ratio, ρ = ~0.61) green emissions from large area (0.7 cm × 0.6 cm) planar surface. The realization of a horizontally assembled nanorod LED device can prove the concept of an innovative idea to fabricate formable and scalable polarized surface LED lighting. PMID:27324568

  19. Horizontally assembled green InGaN nanorod LEDs: scalable polarized surface emitting LEDs using electric-field assisted assembly

    NASA Astrophysics Data System (ADS)

    Park, Hoo Keun; Yoon, Seong Woong; Eo, Yun Jae; Chung, Won Woo; Yoo, Gang Yeol; Oh, Ji Hye; Lee, Keyong Nam; Kim, Woong; Do, Young Rag

    2016-06-01

    In this study, we report the concerted fabrication process, which is easy to transform the size of active emitting area and produce polarized surface light, using the electric-field-assisted assembly for horizontally assembled many tiny nanorod LEDs between two metal electrodes. We fabricate the millions of individually separated 1D nanorod LEDs from 2D nanorod arrays using nanosphere lithography, etching and cutting process of InGaN/GaN LED structure on a flat sapphire substrate. The horizontally assembled InGaN-based nanorods LED device shows bright (~2,130 cd/m2) and uniform polarized (polarization ratio, ρ = ~0.61) green emissions from large area (0.7 cm × 0.6 cm) planar surface. The realization of a horizontally assembled nanorod LED device can prove the concept of an innovative idea to fabricate formable and scalable polarized surface LED lighting.

  20. Horizontally assembled green InGaN nanorod LEDs: scalable polarized surface emitting LEDs using electric-field assisted assembly.

    PubMed

    Park, Hoo Keun; Yoon, Seong Woong; Eo, Yun Jae; Chung, Won Woo; Yoo, Gang Yeol; Oh, Ji Hye; Lee, Keyong Nam; Kim, Woong; Do, Young Rag

    2016-01-01

    In this study, we report the concerted fabrication process, which is easy to transform the size of active emitting area and produce polarized surface light, using the electric-field-assisted assembly for horizontally assembled many tiny nanorod LEDs between two metal electrodes. We fabricate the millions of individually separated 1D nanorod LEDs from 2D nanorod arrays using nanosphere lithography, etching and cutting process of InGaN/GaN LED structure on a flat sapphire substrate. The horizontally assembled InGaN-based nanorods LED device shows bright (~2,130 cd/m(2)) and uniform polarized (polarization ratio, ρ = ~0.61) green emissions from large area (0.7 cm × 0.6 cm) planar surface. The realization of a horizontally assembled nanorod LED device can prove the concept of an innovative idea to fabricate formable and scalable polarized surface LED lighting. PMID:27324568

  1. Chloride ion addition for controlling shapes and properties of silver nanorods capped by polyvinyl alcohol synthesized using polyol method

    NASA Astrophysics Data System (ADS)

    Junaidi, Yunus, Muhammad; Triyana, Kuwat; Harsojo, Suharyadi, Edi

    2016-04-01

    We report our investigation on the effect of chloride ions on controlling the shapes and properties of silver nanorods (AgNRs) synthesized using a polyol method. In this study, we used polyvinyl alcohol (PVA) as a capping agent and sodium chloride (NaCl) as a salt precursor and performed at the oil bath temperature of 140°C. The chloride ions originating from the NaCl serve to control the growth of the silver nanorods. Furthermore, the synthesized silver nanorods were characterized using SEM and XRD. The results showed that besides being able to control the growth of AgCl atoms, the chloride ions were also able to control the growth of multi-twinned-particles into the single crystalline of silver nanorods by micrometer-length. At an appropriate concentration of NaCl, the diameter of silver nanorods decreased significantly compared to that of without chloride ion addition. This technique may be useful since a particular diameter of silver nanorods affects a particular application in the future.

  2. Au sensitized ZnO nanorods for enhanced liquefied petroleum gas sensing properties

    NASA Astrophysics Data System (ADS)

    Nakate, U. T.; Bulakhe, R. N.; Lokhande, C. D.; Kale, S. N.

    2016-05-01

    The zinc oxide (ZnO) nanorods have grown on glass substrate by spray pyrolysis deposition (SPD) method using zinc acetate solution. The phase formation, surface morphology and elemental composition of ZnO films have been investigated using X-ray diffraction, field emission scanning electron microscopy (FE-SEM), atomic force microscopy (AFM) and energy dispersive X-ray (EDX) techniques. The liquefied petroleum gas (LPG) sensing response was remarkably improved by sensitization of gold (Au) surface noble metal on ZnO nanorods film. Maximum LPG response of 21% was observed for 1040 ppm of LPG, for pure ZnO nanorods sample. After Au sensitization on ZnO nanorods film sample, the LPG response greatly improved up to 48% at operating temperature 623 K. The improved LPG response is attributed Au sensitization with spill-over mechanism. Proposed model for LPG sensing mechanism discussed.

  3. Electrical conduction and NO2 gas sensing properties of ZnO nanorods

    NASA Astrophysics Data System (ADS)

    Şahin, Yasin; Öztürk, Sadullah; Kılınç, Necmettin; Kösemen, Arif; Erkovan, Mustafa; Öztürk, Zafer Ziya

    2014-06-01

    Thermally stimulated current (TSC), photoresponse and gas sensing properties of zinc oxide (ZnO) nanorods were investigated depending on heating rates, illumination and dark aging times with using sandwich type electrode system. Vertically aligned ZnO nanorods were grown on indium tin oxide (ITO) coated glass substrate by hydrothermal process. TSC measurements were performed at different heating rates under constant potential. Photoresponse and gas sensing properties were investigated in dry air ambient at 200 °C. For gas sensing measurements, ZnO nanorods were exposed to NO2 (100 ppb to 1 ppm) in dark and illuminated conditions and the resulting resistance transient was recorded. It was found from dark electrical measurements that the dependence of the dc conductivity on temperature followed Mott's variable range hopping (VRH) model. In addition, response time and recovery times of ZnO nanorods to NO2 gas decreased by exposing to white light.

  4. Straight β-SiC nanorods synthesized by using C-Si-SiO2

    NASA Astrophysics Data System (ADS)

    Lai, H. L.; Wong, N. B.; Zhou, X. T.; Peng, H. Y.; Au, Frederick C. K.; Wang, N.; Bello, I.; Lee, C. S.; Lee, S. T.; Duan, X. F.

    2000-01-01

    Straight beta-silicon carbide nanorods have been grown on silicon wafers using hot filament chemical vapor deposition with iron particles as catalyst. A plate made of a C-Si-SiO2 powder mixture was used as carbon and silicon sources. Hydrogen, which was the only gas fed into the deposition system, acts both as a reactant and as a mass transporting medium. The diameter of the β-SiC nanorod ranged from 20 to 70 nm, while its length was approximately 1 μm. A growth mechanism of beta-silicon carbide nanorods was proposed. The field emission properties of the beta-silicon carbide nanorods grown on the silicon substrate are also reported.

  5. Zinc oxide nanorod growth on gold islands prepared by microsphere lithography on silicon and quartz.

    PubMed

    Blackledge, Charles W; Szarko, Jodi M; Dupont, Aurélie; Chan, George H; Read, Elizabeth L; Leone, Stephen R

    2007-09-01

    Gold islands, vapor deposited on silicon and quartz by microsphere lithography patterning, are used to nucleate arrays of ZnO nanorods. ZnO is grown on approximately 0.32 microm2 Au islands by carbothermal reduction in a tube furnace. Scanning electron microscopy (SEM) and energy dispersive atomic X-ray spectroscopy (EDS) confirm that the gold effectively controls the sites of nucleation of ZnO. Atomic force microscopy (AFM) shows that approximately 30 nm diameter nanorods grow horizontally, along the surface. Alloy droplets that are characteristic of the vapor-liquid-solid (VLS) mechanism are observed at the tips of the nanorods. The spatial growth direction of VLS catalyzed ZnO nanorods is along the substrate when they nucleate from gold islands on silicon and quartz. The energy of adhesion of the VLS droplet to the surface can account for the horizontal growth. PMID:18019171

  6. Temperature dependence of the growth of ZnO nanorod arrays by electrochemical deposition

    NASA Astrophysics Data System (ADS)

    Kim, Hyunghoon; Moon, Jin Young; Lee, Ho Seong

    2011-03-01

    ZnO nanorod arrays were prepared by the electrochemical deposition route on conductive Au/Si substrates. The effect of the bath temperature on the growth of the ZnO nanorod arrays was investigated. With an increase in bath temperature from 30°C to 80°C, the deposited ZnO changed from an amorphous structure to a hexagonal crystal structure. The ZnO nanorod arrays grown above 50°C were dense and vertically well-aligned. Scanning and transmission electron microscopy results showed that the diameter of the hexagon-shaped ZnO nanorod arrays ranged from 100 nm to 180 nm and the length was about 500 nm. On the basis of the characteristics of the ZnO crystal structure and the effect of the bath temperature, the growth mechanism is described.

  7. Growth-induced Stacking Faults of ZnO Nanorods Probed by Spatial Resolved Cathodoluminescence

    NASA Astrophysics Data System (ADS)

    Xie, Yong; Jie, Wan-Qi; Wang, Tao; Wiedenmann, Michael; Neuschl, Benjamin; Madel, Manfred; Wang, Ya-Bin; Feneberg, Martin; Thonke, Klaus

    2012-07-01

    Low density ZnO nanorods are grown by modified chemical vapor deposition on silicon substrates using gold as a catalyst. We use high resolution photoluminescence spectroscopy to gain the optical properties of these nanorods in large scale. The as-grown samples show sharp near-band-gap luminescence with a full width at half maximum of bound exciton peaks at about 300 μeV, and the ratio of ultraviolet/yellow luminescence larger than 100. Highly spatial and spectral resolved scanning electron microscope-cathodoluminescence is performed to excite the ZnO nanorods in single rods or different positions of single rods with the vapour-solid growth mechanism. The bottom of the nanorod has a 3.31-eV luminescence, which indicates that basal plane stacking faults are related to the defects that are created at the first stage of growth due to the misfit between ZnO and Si.

  8. Light emission from electrically stressed ZnO nanorods

    NASA Astrophysics Data System (ADS)

    Lucera, Luca; Adnane, Lhacene; Cil, Kadir; Manthina, Venkata; Agrios, Alexander; Silva, Helena; Gokirmak, Ali

    2012-02-01

    Zinc oxide (ZnO) nanorods were grown on various substrates by a chemical growth process based on a ZnO seed solution, and starting from Zinc acetate (ZnAc) material. The nanorods were grown on insulating silicon (low doped) and oxidized silicon substrates, and also over patterned conducting (highly-doped) nanocrystalline silicon microwires. When high voltage is applied directly to the ZnO film using tungsten needles (˜ 50-60 V across ˜ 5-10 μm), high intensity blue and white light emission is observed, both in air and under high vacuum (10-4 - 10-5 Torr). Blue light appears as broad bright flashes covering a large area whereas white light is more localized and appears to come from individual nanostructures. The results suggest a combination of electroluminescence and photoluminescence processes that take place after an electrical breakdown (possibly across individual ZnO nanorods) that is observed as an exponential increase in current. Percolative conduction and light paths are also observed during the measurements. Measurements of the ZnO films of rods on conducting silicon substrate give more repeatable results, likely due to the higher probability of conducting paths between the two probes. The electrical stress results in significant self-heating and modification of the ZnO nanostructures and the contacts.[4pt] [1] Greene L. E. et al. Solution-Grown Zinc oxide nanowires. Innorganic Chemistry. Vol 45. 7535-7543. (2006)

  9. Infrared Resonances in Plasmonic Nanorod and Nanoarc Antennas

    NASA Astrophysics Data System (ADS)

    Lawson, Andrew; Ellis, Chase; Tischler, Joseph; Rabin, Oded

    Tunability of the frequency and polarization of localized surface plasmon resonances (LSPR) of nanostructures is crucial for their implementation in nanophotonics applications such as photovoltaics, chiroptical spectroscopy, and infrared detection. We report spectroscopic data of plasmonic nanorods and nanoarcs collected by polarized Fourier transform infrared reflectance spectroscopy (FTIR). The effects of the nanostructure material, geometry and substrate material are investigated by patterning gold and aluminum structures with varying length on silicon and glass substrates, as well as on anodic aluminum oxide, a cost effective alternative to standard transparent substrates. By varying such parameters for straight rods and arcs, we find that the measured LSPR frequencies of our nanostructures span the mid-infrared spectral range (λ=2-12 microns). However, we find that bending the nanostructures (i.e., forming arcs rather than straight rods) results in additional resonances with unique polarizations not observed in straight nanorods. We find that the nanorods exhibit half-wave antenna behavior which can be modeled using antenna theory with a linearly scaled effective wavelength which accounts for structure dimensions and material.

  10. Thickness-controlled synthesis of vertically aligned c-axis oriented ZnO nanorod arrays: Effect of growth time via novel dual sonication sol-gel process

    NASA Astrophysics Data System (ADS)

    Firdaus Malek, Mohd; Hafiz Mamat, Mohamad; Soga, Tetsuo; Rahman, Saadah Abdul; Abu Bakar, Suriani; Syakirin Ismail, Ahmad; Mohamed, Ruziana; Alrokayan, Salman A. H.; Khan, Haseeb A.; Rusop Mahmood, Mohamad

    2016-01-01

    Zinc-oxide (ZnO) nanorod arrays were successfully prepared by using dual sonication sol-gel process. Field emission scanning electron microscopy revealed that the nanorods exhibited a hexagonal structure with a flat-end facet. The nanorods displayed similar surface morphologies and grew uniformly on the seed layer substrate, with the average diameter slightly increasing to the range of 65 to 80 nm after being immersed for varying growth times. Interestingly, thickness measurements indicated that the thicknesses of the samples increased as the growth time was extended. In addition, the X-ray diffraction spectra indicated that the prepared ZnO nanorods with a hexagonal wurtzite structure grew preferentially along the c-axis. Therefore, we can conclude that the diameter, length, and orientation of the ZnO nanorod arrays along the c-axis are controllable by adjusting the growth time, motivating us to further explore the growth mechanisms of ZnO nanorods.

  11. The unusual effect of AgNO3 on the growth of Au nanostructures and their catalytic performance

    NASA Astrophysics Data System (ADS)

    Li, Xingliang; Yang, Yun; Zhou, Guangju; Han, Shuhua; Wang, Wenfang; Zhang, Lijie; Chen, Wei; Zou, Chao; Huang, Shaoming

    2013-05-01

    Au nanostructures attract much attention due to their potential applications in many fields. The controlled synthesis is critical to their properties modulation and applications. AgNO3-assisted synthesis is a widely used method for controllably preparing Au nanostructures in aqueous system. Herein, the effect of AgNO3 on the growth of Au nanostructures in polyol is studied. We observe an unusual effect that AgNO3 can induce the formation of pentatwinned Au nanostructures (nanorods and decahedra) and block the growth of Au nanorods. More interestingly, this blocking effect can be tuned through controlling the amount of AgNO3. A moderate amount of AgNO3 facilitates the formation of Au nanorods. A large amount of AgNO3 completely blocks the growth of nanorods and favors the formation of high quality decahedra (decahedra can be considered as nanorods with 0 nm longitudinal length). Besides, this blocking effect also allows preparation of different high-index-faceted Au nanobipyramids. These prepared Au nanostructures further serve as starting templates to fabricate other heterostructured Au/Ag nanomaterials, such as Ag-Au-Ag segmental nanorods, Au@Ag core-shelled nanostructures. The prepared nanostructures exhibit size- and structure-dependent catalytic performance in the reduction of p-nitrophenol to p-aminophenol by sodium borohydride.Au nanostructures attract much attention due to their potential applications in many fields. The controlled synthesis is critical to their properties modulation and applications. AgNO3-assisted synthesis is a widely used method for controllably preparing Au nanostructures in aqueous system. Herein, the effect of AgNO3 on the growth of Au nanostructures in polyol is studied. We observe an unusual effect that AgNO3 can induce the formation of pentatwinned Au nanostructures (nanorods and decahedra) and block the growth of Au nanorods. More interestingly, this blocking effect can be tuned through controlling the amount of AgNO3. A moderate

  12. Templating gold nanorods with liquid crystalline DNA

    NASA Astrophysics Data System (ADS)

    De Sio, Luciano; Annesi, Ferdinanda; Placido, Tiziana; Comparelli, Roberto; Bruno, Vincenzo; Pane, Alfredo; Palermo, Giovanna; Curri, Maria Lucia; Umeton, Cesare; Bartolino, Roberto

    2015-02-01

    A liquid crystalline, negatively charged, whole-genome DNA is exploited to organize positively charged gold nanorods (GNRs) by means of electrostatic interaction. A mesoscopic alignment of the composite system along a preferred direction is obtained by casting a droplet of the DNA-nanorods solution onto an untreated glass substrate. Gel electrophoresis analysis enables evaluating the effective electric charge of the system, thus minimizing the DNA fragmentation. Polarized optical microscopy, combined with transmission and scanning electron microscopy, shows that, up to 20% in weight of GNR solution, the system exhibits both a long range order, induced by the liquid crystalline phase of the DNA, and a nanoscale organization, due to the DNA self-assembly. These evidences are confirmed by a polarized spectral analysis, which also points out that the optical properties of GNRs strongly depend on the polarization of the impinging probe light. The capability to organize plasmonic nanoparticles by means of DNA material represents a significant advance towards the realization of life science inspired optical materials.

  13. Self-Catalyzed Growth of Vertically Aligned InN Nanorods by Metal-Organic Vapor Phase Epitaxy.

    PubMed

    Tessarek, C; Fladischer, S; Dieker, C; Sarau, G; Hoffmann, B; Bashouti, M; Göbelt, M; Heilmann, M; Latzel, M; Butzen, E; Figge, S; Gust, A; Höflich, K; Feichtner, T; Büchele, M; Schwarzburg, K; Spiecker, E; Christiansen, S

    2016-06-01

    Vertically aligned hexagonal InN nanorods were grown mask-free by conventional metal-organic vapor phase epitaxy without any foreign catalyst. The In droplets on top of the nanorods indicate a self-catalytic vapor-liquid-solid growth mode. A systematic study on important growth parameters has been carried out for the optimization of nanorod morphology. The nanorod N-polarity, induced by high temperature nitridation of the sapphire substrate, is necessary to achieve vertical growth. Hydrogen, usually inapplicable during InN growth due to formation of metallic indium, and silane are needed to enhance the aspect ratio and to reduce parasitic deposition beside the nanorods on the sapphire surface. The results reveal many similarities between InN and GaN nanorod growth showing that the process despite the large difference in growth temperature is similar. Transmission electron microscopy, spatially resolved energy-dispersive X-ray spectroscopy, X-ray diffraction, X-ray photoelectron spectroscopy, and Raman spectroscopy have been performed to analyze the structural properties. Spatially resolved cathodoluminescence investigations are carried out to verify the optical activity of the InN nanorods. The InN nanorods are expected to be the material of choice for high-efficiency hot carrier solar cells. PMID:27187840

  14. Digital selective fabrication of micro/nano-composite structured TiO2 nanorod arrays by laser direct writing

    NASA Astrophysics Data System (ADS)

    Jiang, Wei; He, Xiaoning; Liu, Hongzhong; Yin, Lei; Shi, Yongsheng; Ding, Yucheng

    2014-11-01

    In this article, we report on the digital selective fabrication of micro/nano-composite structured TiO2 nanorod arrays by laser direct writing. The pattern of TiO2 nanorod arrays can be easily designed and fabricated by laser scanning technology integrated with a computer-aided design system, which allows a high degree of freedom corresponding to the various pattern design demands. The approach basically involves the hydrothermal growth of TiO2 nanorod arrays on a transparent conductive substrate, the micropattern of TiO2 nanorod arrays and surface fluorination treatment. With these micro/nano-composite TiO2 nanorod array based films, we have demonstrated superhydrophilic patterned TiO2 nanorod arrays with rapid water spreading ability and superhydrophobic patterned TiO2 nanorod arrays with an excellent droplet bouncing effect and a good self-cleaning performance. The dynamic behaviours of the water droplets observed on the patterned TiO2 nanorod arrays were demonstrated by experiments and simulated by a finite element method. The approaches we will show are expected to provide potential applications in fields such as self-cleaning, surface protection, anticrawling and microfluidic manipulation.

  15. Gold Nanorods: Evaporative Self-Assembly of Gold Nanorods into Macroscopic 3D Plasmonic Superlattice Arrays (Adv. Mater. 13/2016).

    PubMed

    Li, Penghui; Li, Yong; Zhou, Zhang-Kai; Tang, Siying; Yu, Xue-Feng; Xiao, Shu; Wu, Zhongzhen; Xiao, Quanlan; Zhao, Yuetao; Wang, Huaiyu; Chu, Paul K

    2016-04-01

    On page 2511, X.-F. Yu, P. K. Chu, and co-workers demonstrate the successful fabrication of millimeter-scale three-dimensional superlattice arrays consisting of dense, regular, and vertically aligned gold nanorods by the evaporative self-assembly method. The excellent performance in surface-enhanced Raman scattering indicates applications in plasmonic substrates. PMID:27037942

  16. Synthesis and characterization of hydrothermally grown zinc oxide (ZnO) nanorods for optical waveguide application

    NASA Astrophysics Data System (ADS)

    Pandey, Chandan A.; Rahim, Rafis; Manjunath, S.; Hornyak, Gabor L.; Mohammed, Waleed S.

    2015-07-01

    We report a simple method to synthesize Zinc oxide nanorods, grown without using catalysis with less complicity. This was done by hydrothermal treatment of zinc nitrate and hexamine at 90°C and various times (5- 20h) and also we find that the nanorod size and shape depends on heating rate, temperature and heating time. ZnO nanorods have been investigated for their light guiding ability and their effective index of refraction for use in near air index optical systems by developing a ridge waveguide structure. ZnO nanorod waveguides (100 μm w x 2.5 μm h x 1mm l) were grown on a seeded glass substrate template using hydrothermal process at 90°C. Modification of the substrate surface in order to obtain dense perpendicularly-oriented ordered nanorods induced selective growth. These structures were characterized by SEM, EDX, and XRD. The guiding property, i.e. locally excited photoluminescence propagation along the length of the waveguide, was analyzed with imageprocessing program in MATLAB. Following application of a fiber optic white light source on the ZnO nanostructure, we found that light propagation occurred within the glass substrate. No such propagation occurred if light was applied on uncoated areas of the glass. Modeling of waveguide behavior to determine the number propagating modes was exercised using waveguide mode solver in COMSOL.

  17. Large hexagonal arrays of aligned ZnO nanorods

    NASA Astrophysics Data System (ADS)

    Banerjee, D.; Rybczynski, J.; Huang, J. Y.; Wang, D. Z.; Kempa, K.; Ren, Z. F.

    2005-02-01

    Large-scale truly periodic arrays of vertically aligned zinc oxide nanorods were grown on pre-patterned and pre-annealed gold dots on a-plane sapphire substrates via the vapor liquid solid mechanism. Periodic arrays of triangular gold islands were first patterned on the a-plane sapphire substrates by the nanosphere self-assembly technique. Zinc has been found to be an effective interfacial modifier between gold and sapphire to form single catalytic dots from triangular islands. The successful fabrication of zinc oxide nanowires in truly periodic arrays opens up the possibility of achieving enhanced room-temperature ultraviolet lasing and photonic crystal based devices and sensors.

  18. Interfacial Analysis of (La0.6Sr0.4)(Co0.2Fe0.8)O3-δ Substrates Wetted by Ag-CuO

    SciTech Connect

    Weil, K. Scott; Kim, Jin Yong Y.; Hardy, John S.

    2005-05-01

    Recently a new method of brazing has been developed to hermetically seal high-temperature, solid-state electrochemical devices, such as as oxygen and hydrogen separators, fuel gas reformers, solid oxide fuel cells, and chemical sensors. Based on a two-phase liquid composed of silver and copper oxide, brazing is conducted directly in air without the need of an inert cover gas or the use of surface reactive fluxes. A key issue in the development of this joining technique is understanding the effect of braze composition on wetting behavior. In the present paper we consider the wetting behaviors of two candidate braze filler materials, Ag-CuO and Ag-CuO-TiO2, on a protoypical mixed ionic/electronic conducting oxide substrate, lanthanum strontium cobalt ferrite [(La0.6Sr0.4)(Co0.2Fe0.8)O3-δ]. It was found that additions of CuO to silver exhibit a tremendous effect on both the wettability and joint strength characteristics of the subsequent braze relative to polycrystalline alumina substrates. The effect is particularly significant at low CuO content, with substantial improvements in wetting observed in the 1 – 8 mol% range. The corresponding strength of the brazed polycrystalline alumina joints appears to be maximized at a copper oxide content of 8 mol%, with a maximum room temperature flexural strength approaching that of monolithic alumina. While further increases in oxide content lead to improved wetting on polycrystalline alumina, the effect on joint strength is deleterious. It appears that the formation of a continuous brittle copper-based oxide layer along the interface between the braze and alumina faying surface is responsible for the poor mechanical behavior observed in joints fabricated with higher CuO content brazes.

  19. Highly selective electrodeposition of sub-10 nm crystalline noble metallic nanorods inside vertically aligned multiwall carbon nanotubes.

    PubMed

    Wang, Xuyang; Wang, Ranran; Wu, Qiang; Zhang, Xiaohua; Yang, Zhaohui; Guo, Jun; Chen, Muzi; Tang, Minghua; Cheng, Yajun; Chu, Haibin

    2016-07-01

    In this paper crystalline noble metallic nanorods including Au and Ag with sub-10 nm diameter, are encapsulated within prealigned and open-ended multiwall carbon nanotubes (MWCNTs) through an electrodeposition method. As the external surface of CNTs has been insulated by the epoxy the CNT channel becomes the only path for the mass transport as well as the nanoreactor for the metal deposition. Highly crystallized Au and Ag2O nanorods parallel to the radial direction of CNTs are confirmed by high-resolution transmission electron microscopy, energy dispersive x-ray spectroscopy and x-ray powder diffraction spectroscopy. The Ag2O nanorods are formed by air oxidation on the Ag metals and show a single crystalline structure with (111) planes. The Au nanorods exhibit a complex crystalline structure including twin-crystal and lattice dislocation with (111) and (200) planes. These crystalline noble metallic nanostructures may have important applications for nanocatalysts for fuel cells as well as nanoelectronic and nanophotonic devices. This method is deemed to benefit the precise deposition of other crystalline nanostructures inside CNTs with a small diameter. PMID:27240546

  20. Highly selective electrodeposition of sub-10 nm crystalline noble metallic nanorods inside vertically aligned multiwall carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Wang, Xuyang; Wang, Ranran; Wu, Qiang; Zhang, Xiaohua; Yang, Zhaohui; Guo, Jun; Chen, Muzi; Tang, Minghua; Cheng, Yajun; Chu, Haibin

    2016-07-01

    In this paper crystalline noble metallic nanorods including Au and Ag with sub-10 nm diameter, are encapsulated within prealigned and open-ended multiwall carbon nanotubes (MWCNTs) through an electrodeposition method. As the external surface of CNTs has been insulated by the epoxy the CNT channel becomes the only path for the mass transport as well as the nanoreactor for the metal deposition. Highly crystallized Au and Ag2O nanorods parallel to the radial direction of CNTs are confirmed by high-resolution transmission electron microscopy, energy dispersive x-ray spectroscopy and x-ray powder diffraction spectroscopy. The Ag2O nanorods are formed by air oxidation on the Ag metals and show a single crystalline structure with (111) planes. The Au nanorods exhibit a complex crystalline structure including twin-crystal and lattice dislocation with (111) and (200) planes. These crystalline noble metallic nanostructures may have important applications for nanocatalysts for fuel cells as well as nanoelectronic and nanophotonic devices. This method is deemed to benefit the precise deposition of other crystalline nanostructures inside CNTs with a small diameter.

  1. Characteristics of zinc oxide nanorod array/titanium oxide film heterojunction prepared by aqueous solution deposition

    NASA Astrophysics Data System (ADS)

    Lee, Ming-Kwei; Hong, Min-Hsuan; Li, Bo-Wei

    2016-07-01

    The characteristics of a ZnO nanorod array/TiO2 film heterojunction were investigated. A TiO2 film was prepared on glass by aqueous solution deposition with precursors of ammonium hexafluorotitanate and boric acid at 40 °C. Then, a ZnO seed layer was prepared on a TiO2 film/glass substrate by RF sputtering. A vertically oriented ZnO nanorod array was grown on a ZnO seed layer/TiO2 film/glass substrate by aqueous solution deposition with precursors of zinc nitrate and hexamethylenetetramine (HMT) at 70 °C. After thermal annealing in N2O ambient at 300 °C, this heterojunction used as an oxygen gas sensor shows much better rise time, decay time, and on/off current ratio than as-grown and annealed ZnO nanorods.

  2. Growth of Si nanorods in honeycomb and hexagonal-closed-packed arrays using glancing angle deposition

    SciTech Connect

    Patzig, Christian; Rauschenbach, Bernd; Fuhrmann, Bodo; Leipner, Hartmut S.

    2008-01-15

    Regular arrays of Si nanorods with a circular cross section in hexagonal-closed-packed and triangular cross section in honeycomblike arrangements were grown using glancing angle deposition on Si(100) and fused silica substrates that were patterned with Au dots using self-assembled mono- and double layers of polystyrene nanospheres as an evaporation mask. The Au dots were used as an etching mask for the underlying silica substrates in a reactive ion beam etching process, which greatly enhanced the height of the seeding spaces for the subsequent glancing angle deposition. An elongated shadowing length l of the prepatterned nucleation sites and less growth of Si structures between the surface mounds could be achieved this way. Differences in form, height, and diameter of the Si nanorods grown on either hcp or honeycomb arrays are explained by purely geometrical arguments. Different seed heights and interseed distances are found to be the main reasons for the strong distinctions between the grown nanorod arrays.

  3. Efficient nanorod-based amorphous silicon solar cells with advanced light trapping

    SciTech Connect

    Kuang, Y.; Lare, M. C. van; Polman, A.; Veldhuizen, L. W.; Schropp, R. E. I.; Rath, J. K.

    2015-11-14

    We present a simple, low-cost, and scalable approach for the fabrication of efficient nanorod-based solar cells. Templates with arrays of self-assembled ZnO nanorods with tunable morphology are synthesized by chemical bath deposition using a low process temperature at 80 °C. The nanorod templates are conformally coated with hydrogenated amorphous silicon light absorber layers of 100 nm and 200 nm thickness. An initial efficiency of up to 9.0% is achieved for the optimized design. External quantum efficiency measurements on the nanorod cells show a substantial photocurrent enhancement both in the red and the blue parts of the solar spectrum. Key insights in the light trapping mechanisms in these arrays are obtained via a combination of three-dimensional finite-difference time-domain simulations, optical absorption, and external quantum efficiency measurements. Front surface patterns enhance the light incoupling in the blue, while rear side patterns lead to enhanced light trapping in the red. The red response in the nanorod cells is limited by absorption in the patterned Ag back contact. With these findings, we develop and experimentally realize a further advanced design with patterned front and back sides while keeping the Ag reflector flat, showing significantly enhanced scattering from the back reflector with reduced parasitic absorption in the Ag and thus higher photocurrent generation. Many of the findings in this work can serve to provide insights for further optimization of nanostructures for thin-film solar cells in a broad range of materials.

  4. Nanoheteroepitaxy of GaN on AlN/Si(111) nanorods fabricated by nanosphere lithography

    NASA Astrophysics Data System (ADS)

    Lee, Donghyun; Shin, In-Su; Jin, Lu; Kim, Donghyun; Park, Yongjo; Yoon, Euijoon

    2016-06-01

    Nanoheteroepitaxy (NHE) of GaN on an AlN/Si(111) nanorod structure was investigated by metal-organic chemical vapor deposition. Silica nanosphere lithography was employed to fabricate a periodic hexagonal nanorod array with a narrow gap of 30 nm between the nanorods. We were successful in obtaining a fully coalesced GaN film on the AlN/Si(111) nanorod structure. Transmission electron microscopy revealed that threading dislocation (TD) bending and termination by stacking faults occurred near the interface between GaN and the AlN/Si(111) nanorods, resulting in the reduction of TD density for the NHE GaN layer. The full width at half-maximum of the X-ray rocking curve for (102) plane of the NHE GaN was found to decrease down to 728 arcsec from 1005 arcsec for the GaN layer on a planar AlN/Si(111) substrate, indicating that the crystalline quality of the NHE GaN was improved. Also, micro-Raman measurement showed that tensile stress in the NHE GaN layer was reduced significantly as much as 70% by introducing air voids between the nanorods.

  5. Optoelectrical and magnetic characteristics of Mn doped Zn1-xSnxO nanorods

    NASA Astrophysics Data System (ADS)

    Hsu, Tsung-Yin; Lai, Shang-Hung; Hsieh, Hui-Huang; Lan, Ming-Der; Su, Chih-Chuan; Ho, Mon-Shu

    2013-01-01

    This paper describes a new method of fabricating Mn doped Zn1-xSnxO nanorod arrays on a silicon (111) substrate. The proposed method is a gold catalytic vapor-liquid-solid mechanism in a multi-layer deposition process using nanosphere lithographic patterning. Each step of the growth process was monitored using atomic force microscopy to ensure uniformity in the patterns and nanorods. The crystal structure and characteristics of the Mn doped Zn1-xSnxO nanaorods were determined using the X-ray diffraction analysis, scanning electron microscopy, high resolution transmission electron microscopy, and electron diffraction patterns corresponding to the selected area. The lattice constant along the Z-axis was calculated from the indexed pattern, as approximately 5.1 Å. This differs slightly from what was expected for undoped ZnO nanorods. Energy dispersive X-ray spectrometry provided information related to the chemistry of the ZnO nanorods and electro-optical properties at 363 nm were determined from photoluminescence emissions. Using conductive AFM, the band gap for single doped-ZnO nanorods was determined to be 3-3.45 eV. The magnetic properties were characterized by the measurement of a hysteresis loop. This investigation demonstrates the outstanding potential of patterned Mn doped Zn1-xSnxO nanorods for applications requiring dilute magnetic semiconductors in the future.

  6. Growth mechanism, structure and IR photoluminescence studies of indium nitride nanorods

    NASA Astrophysics Data System (ADS)

    Lan, Z. H.; Wang, W. M.; Sun, C. L.; Shi, S. C.; Hsu, C. W.; Chen, T. T.; Chen, K. H.; Chen, C. C.; Chen, Y. F.; Chen, L. C.

    2004-08-01

    High-quality single crystal indium nitride nanorods were grown on Si substrates by catalytic chemical vapor deposition. Both Raman and high resolution transmission electron microscopic analyses suggested that even a minute amount of oxygen, from the residual oxygen in the growth environment and/or native oxide on the Si, would effectively help the growth of InN nanorods. The In 2O 3 formed on Au nanoparticles helped dissolve nitrogen as a catalyst with the subsequent growth of InN nanorods. Variations in the apparent color and photoluminescence (PL) spectra of the InN nanorods were observed. For the optically brown InN nanorods that exhibited diameters in the range of 30-50 nm, the PL study showed a peak at 1.9 eV, the possible origins of which are discussed. In contrast, for the optically black InN nanorods that exhibited diameters in the range of 50-100 nm, the PL peak at approximately 0.766 eV measured at 20 K was attributed to band edge emission.

  7. Thermo-electrochemical selective growth of ZnO nanorods on any noble metal electrodes

    NASA Astrophysics Data System (ADS)

    You, Xueqiu; Park, Jungil; Choi, Jae-hoon; Pak, James Jungho

    2010-10-01

    Selective growth of ZnO nanorods has been successfully performed on the patterned Au/Ti metal electrode regions on a glass substrate by using a seeded thermo-electrochemical method in an acidic growth solution. The selective growth mechanism of the thermo-electrochemical method was proposed by using a series of chemical reactions for the first time. The thermo-electrochemical selective ZnO growth was performed on the cathode electrode at a temperature below 90 °C. A ZnO seed layer was precoated and selectively etched away from the non-metal regions in order to create the patterned selective nucleation sites on which the precursors are transferred and crystallized into ZnO nanorods. Both the dimensions and the placements of the ZnO nanorods have been simultaneously controlled. Energy dispersive X-ray spectrometry showed that the selectively grown ZnO nanorods consist of only Zn and O, indicating that the selectively grown ZnO nanorods are pure and contamination free. XRD and electron diffraction patterns revealed that the obtained ZnO nanorods have a wurtzite single-crystal structure.

  8. Investigating the optical XNOR gate using plasmonic nano-rods

    NASA Astrophysics Data System (ADS)

    Akhlaghi, Majid; Kaboli, Milad

    2016-04-01

    In this paper, a coherent perfect absorption (CPA)-type XNOR gate based on plasmonic nano particle is proposed. It consists of two plasmonic nano rod arrays on top of two parallel arms with quartz substrate. The operation principle is based on the absorbable formation of a conductive path in the dielectric layer of a plasmonic nano-particles waveguide. Since the CPA efficiency depends strongly on the number of plasmonic nano-rod and the nano rod location, an efficient binary optimization method based the Particle Swarm Optimization (PSO) algorithm is used to design an optimized array of the plasmonic nano-rod in order to achieve the maximum absorption coefficient in the 'off' state and the minimum absorption coefficient in the 'on' state. In Binary PSO (BPSO), a group of birds consists a matrix with binary entries, control the presence ('1‧) or the absence ('0‧) of nano rod in the array.

  9. Hierarchical organization and molecular diffusion in gold nanorod/silica supercrystal nanocomposites

    NASA Astrophysics Data System (ADS)

    Hamon, Cyrille; Sanz-Ortiz, Marta N.; Modin, Evgeny; Hill, Eric H.; Scarabelli, Leonardo; Chuvilin, Andrey; Liz-Marzán, Luis M.

    2016-04-01

    Hierarchical organization of gold nanorods was previously obtained on a substrate, allowing precise control over the morphology of the assemblies and macroscale spatial arrangement. Herein, a thorough description of these gold nanorod assemblies and their orientation within supercrystals is presented together with a sol-gel technique to protect the supercrystals with mesoporous silica films. The internal organization of the nanorods in the supercrystals was characterized by combining focused ion beam ablation and scanning electron microscopy. A mesoporous silica layer is grown both over the supercrystals and between the individual lamellae of gold nanorods inside the structure. This not only prevented the detachment of the supercrystal from the substrate in water, but also allowed small molecule analytes to infiltrate the structure. These nanocomposite substrates show superior Raman enhancement in comparison with gold supercrystals without silica owing to improved accessibility of the plasmonic hot spots to analytes. The patterned supercrystal arrays with enhanced optical and mechanical properties obtained in this work show potential for the practical implementation of nanostructured devices in spatially resolved ultradetection of biomarkers and other analytes.Hierarchical organization of gold nanorods was previously obtained on a substrate, allowing precise control over the morphology of the assemblies and macroscale spatial arrangement. Herein, a thorough description of these gold nanorod assemblies and their orientation within supercrystals is presented together with a sol-gel technique to protect the supercrystals with mesoporous silica films. The internal organization of the nanorods in the supercrystals was characterized by combining focused ion beam ablation and scanning electron microscopy. A mesoporous silica layer is grown both over the supercrystals and between the individual lamellae of gold nanorods inside the structure. This not only prevented the

  10. Fabrication of ZnO nanorods and assessment of changes in optical and gas sensing properties by increasing their lengths

    NASA Astrophysics Data System (ADS)

    Mehrabian, Masood; Mirabbaszadeh, Kavoos; Afarideh, Hossein

    2013-12-01

    We report a low-temperature process to synthesize highly oriented arrays of ZnO nanorods, based on the epitaxial growth of the ZnO seed layer at a low temperature of 70 °C. The ZnO seed layer was deposited by sol-gel process under mild conditions on the glass substrates. The morphologies and crystal structures of the film and nanorods were characterized by x-ray diffraction and scanning electron microscopy, respectively. ZnO nanorods were grown on ZnO seed layers by hydrothermal method. The effect of growth period on the morphology and optical characteristics (e.g. optical transmission and band-gap energy), hydrophilicity and gas sensing properties of the grown ZnO seed layer (film) and nanorods were investigated. The long nanorods on the seed layer were observed. The increase in the length of the nanorods resulted in a significant reduction in the optical band-gap energy of the nanorods, which was attributed to the formation of further defects in the nanorods during their fast growth. The surface of the ZnO nanorods grown for 6 h was relatively hydrophilic (with a water contact angle of 18°). The fabricated sensors were used to gauge different concentrations of ethanol vapor in the air at different temperatures and evaluated the surface resistance of the sensors as a function of operating temperature and ethanol concentrations. The results showed that the sensitivity of the nanorods changed from 1.3 to 6 (at 300 °C) by increasing the growth period.

  11. CONDENSED MATTER: ELECTRONIC STRUCTURE, ELECTRICAL, MAGNETIC, AND OPTICAL PROPERTIES: Growth mechanism and photoluminescence of the SnO2 nanotwists on thin film and the SnO2 short nanowires on nanorods

    NASA Astrophysics Data System (ADS)

    Wang, Bing; Xu, Ping

    2009-01-01

    SnO2 nanotwists on thin film and SnO2 short nanowires on nanorods have been grown on single silicon substrates by using Au-Ag alloying catalyst assisted carbothermal evaporation of SnO2 and active carbon powders. The morphology and the structure of the prepared nanostructures are determined on the basis of field-emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), selected area electronic diffraction (SAED), high-resolution transmission electron microscopy (HRTEM), x-ray diffraction (XRD), Raman and photoluminescence (PL) spectra analysis. The new peaks at 356, 450, and 489 nm in the measured PL spectra of two kinds of SnO2 nanostructures are observed, implying that more luminescence centres exist in these SnO2 nanostructures due to nanocrystals and defects. The growth mechanism of these nanostructures belongs to the vapour-liquid-solid (VLS) mechanism.

  12. Contributions of surface topography and cytotoxicity to the macrophage response to zinc oxide nanorods.

    PubMed

    Zaveri, Toral D; Dolgova, Natalia V; Chu, Byung Hwan; Lee, Jiyeon; Wong, Joey; Lele, Tanmay P; Ren, Fan; Keselowsky, Benjamin G

    2010-04-01

    Macrophages associated with implanted biomaterials are primary mediators of chronic inflammation and foreign body reaction to the implant. Hence, various approaches have been investigated to modulate macrophage interactions with biomaterial surfaces to mitigate inflammatory responses. Nanostructured materials possess unique surface properties, and nanotopography has been reported to modulate cell adhesion and viability in a cell type-dependent manner. Zinc oxide (ZnO) has been investigated in a number of biomedical applications and surfaces presenting well-controlled nanorod structures of ZnO have recently been developed. In order to investigate the influence of nanotopography on macrophage adhesive response, we evaluated macrophage adhesion and viability on ZnO nanorods, compared to a relatively flat sputtered ZnO controls and using glass substrates for reference. We found that although macrophages are capable of initially adhering to and spreading on ZnO nanorod substrates, the number of adherent macrophages on ZnO nanorods was reduced compared to ZnO flat substrate and glass. Additionally adherent macrophage number on ZnO flat substrate was reduced as compared to glass. While these data suggest nanotopography may modulate macrophage adhesion, reduced cell viability on both sputtered and nanorod ZnO substrate indicates appreciable toxicity associated with ZnO. Cell death was apparently not apoptotic, given the lack of activated caspase-3 immunostaining. A decrease in viable macrophage numbers when ZnO substrates were present in the same media verified the role of ZnO substrate dissolution, and dissolved levels of Zn in culture media were quantified. In order to determine long-term physiological responses, ZnO nanorod-coated and sputtered ZnO-coated polyethylene terephthalate (PET) discs were implanted subcutaneously in mice for 14 d. Upon implantation, both ZnO-coated discs resulted in a discontinuous cellular fibrous capsule indicative of unresolved inflammation

  13. A highly efficient fluorescent sensor of explosive peroxide vapor via ZnO nanorod array catalyzed deboronation of pyrenyl borate.

    PubMed

    He, Chao; Zhu, Defeng; He, Qingguo; Shi, Liqi; Fu, Yanyan; Wen, Dan; Cao, Huimin; Cheng, Jiangong

    2012-06-11

    A new strategy capable of detecting explosive peroxide vapor via deboronation reaction induced fluorescence quenching has been developed. Using ordered assembly arrays of ZnO nanorods as catalyzing substrates, the deboronation reaction was 42 times faster than that on quartz substrates, which resulted in a very fast response and high sensitivity. PMID:22552712

  14. 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.

  15. Supercapacitor behavior of α-MnMoO{sub 4} nanorods on different electrolytes

    SciTech Connect

    Purushothaman, K.K.; Cuba, M.; Muralidharan, G.

    2012-11-15

    Graphical abstract: SEM image of α-MnMoO{sub 4} nanorods on FTO substrate. Highlights: ► Synthesis of α-MnMoO{sub 4} nanorods by spin coating method. ► First study on the effect of electrolyte on the pseudocapacitance behavior. ► α-MnMoO{sub 4} nanorods exhibit maximum specific capacitance of 998 F/g. ► At higher scan rates p-TSA electrolyte exhibits superior capacitive behavior. -- Abstract: α-MnMoO{sub 4} nanorods were prepared on conducting glass substrate via sol–gel spin coating method at the optimum doping level. The effect of electrolyte on the pseudocapacitance behavior of the α-MnMoO{sub 4} nanorods was studied using para toluene sulfonic acid (p-TSA), sulfuric acid (H{sub 2}SO{sub 4}) and hydrochloric acid (HCl) as electrolytes. X-ray diffraction analysis reveals the formation of α-MnMoO{sub 4} in monoclinic phase. FTIR spectra contain vibrational bands associated with Mo=O, M–O and Mo–O–Mo bonds. SEM image reveals the formation of nanorods. Supercapacitor behavior has been studied using cyclic voltammetry (CV) analysis. α-MnMoO{sub 4} nanorods exhibit maximum specific capacitance of 998 F/g at a scan rate of 5 mV/s in H{sub 2}SO{sub 4} electrolyte while a specific capacitance of 784 F/g and 530 F/g have been obtained using p-TSA and HCl electrolytes, respectively. At higher scan rates p-TSA electrolyte exhibits superior capacitive behavior than H{sub 2}SO{sub 4}.

  16. Highly Sensitive Detection of Melamine Using a One-Step Sample Treatment Combined with a Portable Ag Nanostructure Array SERS Sensor.

    PubMed

    Cheng, Jie; Su, Xiao-Ou; Yao, Yue; Han, Caiqin; Wang, Shi; Zhao, Yiping

    2016-01-01

    There is an urgent need for rapid and reliable methods able to detect melamine in animal feed. In this study, a quick, simple, and sensitive method for the determination of melamine content in animal feed was developed using surface-enhanced Raman spectroscopy on fabricated Ag nanorod (AgNR) array substrates with a one-step sample extraction procedure. The AgNR array substrates washed by HNO3 solvent (10-7 M) and methanol and showed the good stability within 6 months. The Raman shift at △ν = 682 cm-1 was used as the characteristic melamine peak in the calculations. Sufficient linearity was obtained in the 2-200 μg·g-1 range (R2 = 0.926). The limits of detection and quantification were 0.9 and 2 μg·g-1, respectively. The recovery rates were 89.7-93.3%, with coefficients of variation below 2.02%. The method showed good accuracy compared with the tradition GC-MS analysis. This new protocol only need 2 min to fininsh the detection which could be developed for rapid onsite screening of melamine contamination in quality control and market surveillance applications. PMID:27120183

  17. Highly Sensitive Detection of Melamine Using a One-Step Sample Treatment Combined with a Portable Ag Nanostructure Array SERS Sensor

    PubMed Central

    Cheng, Jie; Su, Xiao-Ou; Yao, Yue; Han, Caiqin; Wang, Shi; Zhao, Yiping

    2016-01-01

    There is an urgent need for rapid and reliable methods able to detect melamine in animal feed. In this study, a quick, simple, and sensitive method for the determination of melamine content in animal feed was developed using surface-enhanced Raman spectroscopy on fabricated Ag nanorod (AgNR) array substrates with a one-step sample extraction procedure. The AgNR array substrates washed by HNO3 solvent (10−7 M) and methanol and showed the good stability within 6 months. The Raman shift at △ν = 682 cm−1 was used as the characteristic melamine peak in the calculations. Sufficient linearity was obtained in the 2–200 μg·g−1 range (R2 = 0.926). The limits of detection and quantification were 0.9 and 2 μg·g−1, respectively. The recovery rates were 89.7–93.3%, with coefficients of variation below 2.02%. The method showed good accuracy compared with the tradition GC-MS analysis. This new protocol only need 2 min to fininsh the detection which could be developed for rapid onsite screening of melamine contamination in quality control and market surveillance applications. PMID:27120183

  18. Near-field coupling and resonant cavity modes in plasmonic nanorod metamaterials.

    PubMed

    Song, Haojie; Zhang, Junxi; Fei, Guangtao; Wang, Junfeng; Jiang, Kang; Wang, Pei; Lu, Yonghua; Iorsh, Ivan; Xu, Wei; Jia, Junhui; Zhang, Lide; Kivshar, Yuri S; Zhang, Lin

    2016-10-14

    Plasmonic resonant cavities are capable of confining light at the nanoscale, resulting in both enhanced local electromagnetic fields and lower mode volumes. However, conventional plasmonic resonant cavities possess large Ohmic losses at metal-dielectric interfaces. Plasmonic near-field coupling plays a key role in a design of photonic components based on the resonant cavities because of the possibility to reduce losses. Here, we study the plasmonic near-field coupling in the silver nanorod metamaterials treated as resonant nanostructured optical cavities. Reflectance measurements reveal the existence of multiple resonance modes of the nanorod metamaterials, which is consistent with our theoretical analysis. Furthermore, our numerical simulations show that the electric field at the longitudinal resonances forms standing waves in the nanocavities due to the near-field coupling between the adjacent nanorods, and a new hybrid mode emerges due to a coupling between nanorods and a gold-film substrate. We demonstrate that this coupling can be controlled by changing the gap between the silver nanorod array and gold substrate. PMID:27607837

  19. Heterostructured TiO2 Nanorod@Nanobowl Arrays for Efficient Photoelectrochemical Water Splitting.

    PubMed

    Wang, Wenhui; Dong, Jingya; Ye, Xiaozhou; Li, Yang; Ma, Yurong; Qi, Limin

    2016-03-01

    Heterostructured TiO2 nanorod@nanobowl (NR@NB) arrays consisting of rutile TiO2 nanorods grown on the inner surface of arrayed anatase TiO2 nanobowls are designed and fabricated as a new type of photoanodes for photoelectrochemical (PEC) water splitting. The unique heterostructures with a hierarchical architecture are readily fabricated by interfacial nanosphere lithography followed by hydrothermal growth. Owing to the two-dimensionally arrayed structure of anatase nanobowls and the nearly radial alignment of rutile nanorods, the TiO2 NR@NB arrays provide multiple scattering centers and hence exhibit an enhanced light harvesting ability. Meanwhile, the large surface area of the NR@NB arrays enhances the contact with the electrolyte while the nanorods offer direct pathways for fast electron transfer. Moreover, the rutile/anatase phase junction in the NR@NB heterostructure improves charge separation because of the facilitated electron transfer. Accordingly, the PEC measurements of the TiO2 NR@NB arrays on the fluoride-doped tin oxide (FTO) substrate show significantly enhanced photocatalytic properties for water splitting. Under AM1.5G solar light irradiation, the unmodified TiO2 NR@NB array photoelectrode yields a photocurrent density of 1.24 mA cm(-2) at 1.23 V with respect to the reversible hydrogen electrode, which is almost two times higher than that of the TiO2 nanorods grown directly on the FTO substrate. PMID:26779803

  20. Defect mediated optical emission of randomly oriented ZnO nanorods and unusual rectifying behavior of Schottky nanojunctions

    NASA Astrophysics Data System (ADS)

    Bayan, Sayan; Mohanta, Dambarudhar

    2011-09-01

    We report on the interrelation of optical emission of randomly oriented ZnO nanorod system with the carrier transport properties of Ag/ZnO nanorod-based rectifying junctions. The ZnO nanorods, exhibiting a hexagonal wurtzite phase, were fabricated by a cost-effective rapid thermal annealing process and at different annealing temperatures. The photoluminescence spectra of the as grown samples have revealed various Zn and O related native defects (e.g., vacancies, interstitials etc.) located at ˜400, 428, 491, and 535 nm. As evident from the I-V characteristic curves, though all the Ag/ZnO nanojunctions show Schottky behavior, the nanorods grown at a temperature of 550 °C and 650 °C are characterized by very large ideality factors of respective values 35.4 and 33.2, apart from displaying unusually high reverse currents. Whereas, the samples grown at 450 °C and 750 °C show usual rectifying nature having relatively lower ideality factors (18.4 and 12.2), along with low leakage-current under reverse biasing. The enhancement or suppression of the reverse currents can be attributed to the eventual lowering or raising of the Schottky barrier heights which result from the variation in the native defect states of various ZnO nanorod systems. Correlating optical events and electrical response through native defects would find scope in assessing figure of merit and sensitivity while making rectifying nanojunctions and single electron devices.

  1. Mechanism of silver(I)-assisted growth of gold nanorods and bipyramids.

    PubMed

    Liu, Mingzhao; Guyot-Sionnest, Philippe

    2005-12-01

    The seed-mediated growth of gold nanostructures is shown to be strongly dependent on the gold seed nanocrystal structure. The gold seed solutions can be prepared such that the seeds are either single crystalline or multiply twinned. With added silver(I) in the cetyltrimethylammonium bromide (CTAB) aqueous growth solutions, the two types of seeds yield either nanorods or elongated bipyramidal nanoparticles, in good yields. The gold nanorods are single crystalline, with a structure similar to those synthesized electrochemically (Yu, Y. Y. et al. J. Phys. Chem. B 1997, 101, 6661). In contrast, the gold bipyramids are pentatwinned. These bipyramids are strikingly monodisperse in shape. This leads to the sharpest ensemble longitudinal plasmon resonance reported so far for metal colloid solutions, with an inhomogeneous width as narrow as 0.13 eV for a resonance at approximately 1.5 eV. Ag(I) plays an essential role in the growth mechanism. Ag(I) slows down the growth of the gold nanostructures. Ag(I) also leads to high-energy side facets that are {110} for the single crystalline gold nanorods and unusually highly stepped {11n} (n approximately 7) for the bipyramid. To rationalize these observations, it is proposed that it is the underpotential deposition of Ag(I) that leads to the dominance of the facets with the more open surface structures. This forms the basis for the one-dimensional growth mechanism of single crystal nanorods, while it affects the shape of the nanostructures growing along a single twinning axis. PMID:16853888

  2. Multilayer TiO2 nanorod cloth/nanorod array electrode for dye-sensitized solar cells and self-powered UV detectors.

    PubMed

    Wang, Zhuoran; Ran, Sihan; Liu, Bin; Chen, Di; Shen, Guozhen

    2012-06-01

    A multilayer TiO(2) nanorod-assembled cloth/nanorod array based electrode was fabricated by transferring different layers of TiO(2) nanorod-assembled cloth (TNRC) onto nanorod array grown on the conducting FTO substrate (titania nanorod, TNR). Combining the superior electron transport characteristics of TNR and outstanding optical properties of TNRC, the nanostructured electrode composed of two layers of TNRC meets the optimized design for high quality dye-sensitized solar cells (DSCs) and self-powered UV detectors. The highest efficiency of 4.02% for DSC under AM 1.5 was achieved with a high short circuit current density of 9.81 mA cm(-2), which was proved to be owing to the enhanced dye anchoring, light scattering and reduced charge recombination. For the photoelectrochemical (PEC) UV detector, the highest quantum efficiency of over 46% was obtained and a high photocurrent response of 0.271 mA cm(-2) was observed, together with the excellent self-powered, fast response and "visible blind" characteristics. A perfect linear response to the changed low-power signal indicates great potential for practical applications. PMID:22549639

  3. Effect of Ni layer thickness and soldering time on intermetallic compound formation at the interface between molten Sn-3.5Ag and Ni/Cu substrate

    SciTech Connect

    Choi, W.K.; Lee, H.M.

    1999-11-01

    The binary eutectic Sn-3.5wt.%Ag alloy was soldered on the Ni/Cu plate at 250 C, the thickness of the Ni layer changing from 0 through 2 and 4 {micro}m to infinity, and soldering time changing from 30 to 120 s at intervals of 30 s. The infinite thickness was equivalent to the bare Ni plate. The morphology, composition and phase identification of the intermetallic compound (IMC, hereafter) formed at the interface were examined. Depending on the initial Ni thickness, different IMC phases were observed at 30 s: Cu{sub 6}Sn{sub 5} on bare Cu, detestable NiSn{sub 3} + Ni{sub 3}Sn{sub 4} on Ni(2 {micro}m)/Cu, Ni{sub 3}Sn{sub 4} on Ni(4 {micro}m)/Cu, and Ni{sub 3}Sn + Ni{sub 3}Sn{sub 4} on bare Ni. With increased soldering time, a Cu-Sn-based {eta}-(Cu{sub 6}Sn{sub 5}){sub 1{minus}x}Ni{sub x} phase formed under the pre-formed Ni-Sn IMC layer both at 60s in the Ni(2 {micro}m)/Cu plate and at 90s in the Ni(4 {micro}m)/Cu plate. The two-layer IMC pattern remained thereafter. The wetting behavior of each joint was different and it may have resulted from the type of IMC formed on each plate. The thickness of the protective Ni layer over the Cu plate was found to be an important factor in determining the interfacial reaction and the wetting behavior.

  4. NiO nanosheet/TiO2 nanorod-constructed p-n heterostructures for improved photocatalytic activity

    NASA Astrophysics Data System (ADS)

    Sun, Bin; Zhou, Guowei; Gao, Tingting; Zhang, Huaijin; Yu, Haohai

    2016-02-01

    NiO nanosheet/acid-corroded TiO2 nanorod (A-TiO2 nanorod) heterostructures with high photocatalytic activity were successfully fabricated via a facile and low-cost hydrothermal route. The as-prepared heterostructures featured NiO nanosheets with uniformly assembled A-TiO2 nanorods and a rough surface. The morphology, structure, and photoelectric properties of the pristine NiO nanosheets and TiO2-based nanomaterials were characterized in detail, and results revealed that secondary NiO nanosheets were successfully grown on TiO2 nanorod substrates to achieve a p-n heterostructure between the cubic structure NiO and the TiO2 anatase phase. In comparison with P25, NiO nanosheets, TiO2 nanorods, and A-TiO2 nanorods, the proposed heterostructures exhibited markedly enhanced photocatalytic activity for the degradation of methyl orange under UV light irradiation. Specifically, the NiO nanosheet/A-TiO2 nanorod heterostructures exhibited the best photocatalytic activity, achieving 100% photocatalytic efficiency within 20 min. The observed enhancement in photocatalytic activity was attributed to the synergetic contributions of p-n heterostructures and the large specific surface area of the catalyst, which may improve the separation of photogenerated electron-hole pairs and prolong the lifetime of charge carriers. The heterostructures could be easily recycled without observable decreases in photocatalytic activity because of their one-dimensional nanostructural property.

  5. Ultra-violet Sensing Characteristic and Field Emission Properties of Vertically Aligned Aluminum Doped Zinc Oxide Nanorod Arrays

    SciTech Connect

    Mamat, M. H.; Malek, M. F.; Musa, M. Z.; Khusaimi, Z.; Rusop, M.

    2011-05-25

    Ultra-violet (UV) sensing behavior and field emission characteristic have been investigated on vertically aligned aluminum (Al) doped zinc oxide (ZnO) nanorod arrays prepared using sol-gel immersion method. Uniform and high coverage density of ZnO nanorod arrays have been successfully deposited on seeded-catalyst coated substrates. The synthesized nanorods have diameter sizes between 50 nm to 150 nm. The XRD spectra show Al doped ZnO nanorod array has high crystallinity properties with the dominancy of crystal growth along (002) plane or c-axis. UV photoresponse measurement indicates that Al doped ZnO nanorod array sensitively detects UV light as shown by conductance increment after UV illumination exposure. The nanorod array shows good field emission properties with low turn on field and threshold field at 2.1 V/{mu}m and 5.6 V/{mu}m, respectively. The result suggested that Al doped ZnO nanorod arrays prepared by low-cost sol-gel immersion method show promising result towards fabrication of multi applications especially in UV photoconductive sensor and field emission displays.

  6. VLS-like growth and characterizations of dense ZnO nanorods grown by e-beam process

    NASA Astrophysics Data System (ADS)

    Agarwal, D. C.; Chauhan, R. S.; Avasthi, D. K.; Sulania, I.; Kabiraj, D.; Thakur, P.; Chae, K. H.; Chawla, Amit; Chandra, R.; Ogale, S. B.; Pellegrini, G.; Mazzoldi, P.

    2009-02-01

    We present a new approach to produce ZnO nanorods in a reproducible manner at a temperature lower than other physical vapour deposition techniques, such as the vapour-liquid-solid mechanism. Arrays of well-aligned ZnO nanorods of uniform diameter have been synthesized on the Si substrate precoated with Au, using a simple electron beam evaporation method without the flow of any carrier gas. Scanning electron microscopy and atomic force microscopy characterizations show that as-grown nanorods are well aligned and uniform in diameter. X-ray diffraction measurements and clear lattice fringes in high-resolution transmission electron microscopy image show the growth of good quality polycrystalline hexagonal ZnO nanorods and a lang0 0 2rang growth direction. The polarization-dependent studies of near edge x-ray absorption fine structure (NEXAFS) are performed to investigate the electronic structure of the zinc and oxygen ions. The analysis of NEXAFS spectra at different angles of incidence of photon flux indicates the formation of ZnO nanorods having anisotropic behaviour of O and Zn states. The photoluminescence spectrum exhibits strong ultraviolet emission at 385 nm and the UV-visible spectrum also shows a band-gap transition around 390 nm indicating the good quality of nanorods. The catalytic growth mechanism of the ZnO nanorods is discussed on the basis of experimental results in this work.

  7. Fabrication and resistive switching characteristics of high compact Ga-doped ZnO nanorod thin film devices

    NASA Astrophysics Data System (ADS)

    Yao, I.-Chuan; Lee, Dai-Ying; Tseng, Tseung-Yuen; Lin, Pang

    2012-04-01

    This study investigates the resistive switching behavior of Ga-doped ZnO (GZO) nanorod thin films with various Ga/Zn molar ratios. Vertically well-aligned and uniform GZO nanorod thin films were successfully grown on Au/Ti/SiO2/p-Si substrates using an aqueous solution method. X-ray diffraction (XRD) results indicate that GZO nanorods have [0001] highly preferred orientation. Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) observations show the formation of highly ordered and dense nanorod thin films. These compact GZO nanorod thin films can be used to make resistive switching memory devices. Such memory devices can be reversibly switched between ON and OFF states, with a stable resistance ratio of ten times, narrow dispersion of ON and OFF voltages, and good endurance performance of over 100 cycles. The resistive switching mechanism in these devices is related to the formation and rupture of conducting filaments consisting of oxygen vacancies, occurring at interfaces between GZO nanorods (grain boundaries). Results show that the resulting compact GZO nanorod thin films have a high potential for resistive memory applications.

  8. Growth and characterization of V2O5 nanorods deposited by spray pyrolysis at low temperatures

    NASA Astrophysics Data System (ADS)

    Abd-Alghafour, N. M.; Ahmed, Naser M.; Hassan, Zai.; Mohammad, Sabah M.; Bououdina, M.

    2016-07-01

    Vanadium pentoxide (V2O5) nanorods were deposited by spray pyrolysis on preheated glass substrates at low temperatures. The influence of substrate temperature on the crystallization of V2O5 has been investigated. X-ray diffraction analysis (XRD) revealed that the films deposited at Tsub = 300°C were orthorhombic structures with preferential along (001) direction. Formation of nanorods from substrate surface which led to the formation of films with small-sized and rod-shaped nanostructure is observed by field scanning electron microscopy. Optical transmittance in the visible range increases to reach a maximum value of about 80% for a substrate temperature of 350°C. PL spectra reveal one main broad peak centered around 540 nm with high intensity.

  9. Study of transport properties of copper/zinc-oxide-nanorods-based Schottky diode fabricated on textile fabric

    NASA Astrophysics Data System (ADS)

    Khan, Azam; Hussain, Mushtaque; Abbasi, Mazhar Ali; Hussain Ibupoto, Zafar; Nur, Omer; Willander, Magnus

    2013-12-01

    In this work, a copper/zinc-oxide (ZnO)-nanorods-based Schottky diode was fabricated on the textile fabric substrate. ZnO nanorods were grown on a silver-coated textile fabric substrate by using the hydrothermal route. Scanning electron microscopy and x-ray diffraction techniques were used for the structural study. The electrical characterization of copper/ZnO-nanorods-based Schottky diodes was investigated by using a semiconductor parameter analyzer and an impedance spectrometer. The current density-voltage (J-V) and capacitance-voltage (C-V) measurements were used to estimate the electrical parameters. The threshold voltage (Vth), ideality factor (η), barrier height (ϕb), reverse saturation current density (Js), carrier concentration (ND) and built-in potential (Vbi) were determined by using experimental data and (simulated) curve fitting. This study describes the possible fabrication of electronic and optoelectronic devices on textile fabric substrate with an acceptable performance.

  10. Impact of Nanosize on Supercapacitance: Study of 1D Nanorods and 2D Thin-Films of Nickel Oxide.

    PubMed

    Patil, Ranjit A; Chang, Cheng-Ping; Devan, Rupesh S; Liou, Yung; Ma, Yuan-Ron

    2016-04-20

    We synthesized unique one-dimensional (1D) nanorods and two-dimensional (2D) thin-films of NiO on indium-tin-oxide thin-films using a hot-filament metal-oxide vapor deposition technique. The 1D nanorods have an average width and length of ∼100 and ∼500 nm, respectively, and the densely packed 2D thin-films have an average thickness of ∼500 nm. The 1D nanorods perform as parallel units for charge storing. However, the 2D thin-films act as one single unit for charge storing. The 2D thin-films possess a high specific capacitance of ∼746 F/g compared to 1D nanorods (∼230 F/g) using galvanostatic charge-discharge measurements at a current density of 3 A/g. Because the 1D NiO nanorods provide more plentiful surface areas than those of the 2D thin-films, they are fully active at the first few cycles. However, the capacitance retention of the 1D nanorods decays faster than that of the 2D thin-films. Also, the 1D NiO nanorods suffer from instability due to the fast electrochemical dissolution and high nanocontact resistance. Electrochemical impedance spectroscopy verifies that the low dimensionality of the 1D NiO nanorods induces the unavoidable effects that lead them to have poor supercapacitive performances. On the other hand, the slow electrochemical dissolution and small contact resistance in the 2D NiO thin-films favor to achieve high specific capacitance and great stability. PMID:27028491

  11. Synthesis and characterization of silicon nanorod on n-type porous silicon.

    PubMed

    Behzad, Kasra; Mat Yunus, Wan Mahmood; Bahrami, Afarin; Kharazmi, Alireza; Soltani, Nayereh

    2016-03-20

    This work reports a new method for growing semiconductor nanorods on a porous silicon substrate. After preparation of n-type porous silicon samples, a thin layer of gold was deposited on them. Gold deposited samples were annealed at different temperatures. The structural, thermal, and optical properties of the samples were studied using a field emission scanning electron microscope (FESEM), photoacoustic spectroscopy, and photoluminescence spectroscopy, respectively. FESEM analysis revealed that silicon nanorods of different sizes grew on the annealed samples. Thermal behavior of the samples was studied using photoacoustic spectroscopy. Photoluminescence spectroscopy showed that the emission peaks were degraded by gold deposition and attenuated for all samples by annealing. PMID:27140545

  12. Shape controllable synthesis of ZnO nanorod arrays via vapor phase growth

    NASA Astrophysics Data System (ADS)

    Sun, Xiaochen; Zhang, Hongzhou; Xu, Jun; Zhao, Qing; Wang, Rongming; Yu, Dapeng

    2004-03-01

    ZnO nanorod arrays with peculiar morphologies were synthesized on (111)-oriented Si substrate and glass via a vapor phase growth. The morphology of the individual nanorod can be flat-headed bottle-like, and needle-like, which depends on the deposition positions relative to the source materials in the presence of a controlling element Se. In addition, the arrays of all the three morphologies exhibit good alignment and high coverage. This fabrication technique can be also used to direct the controllable growth of other nanomaterials with similar morphologies.

  13. An Electrochemical Glucose Sensor Based on Zinc Oxide Nanorods.

    PubMed

    Marie, Mohammed; Mandal, Sanghamitra; Manasreh, Omar

    2015-01-01

    A glucose electrochemical sensor based on zinc oxide (ZnO) nanorods was investigated. The hydrothermal sol-gel growth method was utilized to grow ZnO nanorods on indium tin oxide-coated glass substrates. The total active area of the working electrode was 0.3 × 0.3 cm2 where titanium metal was deposited to enhance the contact. Well aligned hexagonal structured ZnO nanorods with a diameter from 68 to 116 nm were obtained. The excitonic peak obtained from the absorbance spectroscopy was observed at ~370 nm. The dominant peak of Raman spectroscopy measurement was at 440 cm(-1), matching with the lattice vibration of ZnO. The uniform distribution of the GOx and Nafion membrane that has been done using spin coating technique at 4000 rotations per minute helps in enhancing the ion exchange and increasing the sensitivity of the fabricated electrochemical sensor. The amperometric response of the fabricated electrochemical sensor was 3 s. The obtained sensitivity of the fabricated ZnO electrochemical sensor was 10.911 mA/mM·cm2 and the lower limit of detection was 0.22 µM. PMID:26263988

  14. Templated electrodeposition and photocatalytic activity of cuprous oxide nanorod arrays.

    PubMed

    Haynes, Keith M; Perry, Collin M; Rivas, Marlene; Golden, Teresa D; Bazan, Antony; Quintana, Maria; Nesterov, Vladimir N; Berhe, Seare A; Rodríguez, Juan; Estrada, Walter; Youngblood, W Justin

    2015-01-14

    Cuprous oxide (Cu2O) nanorod arrays have been prepared via a novel templated electrodeposition process and were characterized for their photocatalytic behavior in nonaqueous photoelectrochemical cells. Zinc oxide (ZnO) nanorod films serve as sacrificial templates for the in situ formation of polymer nanopore membranes on transparent conductive oxide substrates. Nitrocellulose and poly(lactic acid) are effective membrane-forming polymers that exhibit different modes of template formation, with nitrocellulose forming conformal coatings on the ZnO surface while poly(lactic acid) acts as an amorphous pore-filling material. Robust template formation is sensitive to the seeding method used to prepare the precursor ZnO nanorod films. Photoelectrochemical cells prepared from electrodeposited Cu2O films using methyl viologen as a redox shuttle in acetonitrile electrolyte exhibit significant charge recombination that can be partially suppressed by a combination of surface passivation methods. Surface-passivated nanostructured Cu2O films show enhanced photocurrent relative to planar electrodeposited Cu2O films of similar thickness. We have obtained the highest photocurrent ever reported for electrodeposited Cu2O in a nonaqueous photoelectrochemical cell. PMID:25455203

  15. 3D silver nanoparticles decorated zinc oxide/silicon heterostructured nanomace arrays as high-performance surface-enhanced Raman scattering substrates.

    PubMed

    Huang, Jian; Chen, Feng; Zhang, Qing; Zhan, Yonghua; Ma, Dayan; Xu, Kewei; Zhao, Yongxi

    2015-03-18

    Three-dimensional (3D) hierarchical nanostructures have been considered as one of the most promising surface-enhanced Raman spectroscopy (SERS) substrates because of the ordered arrangement of high-density hotspots along the third dimension direction. Herein, we reported a unique 3D nanostructure for SERS detection based on silver nanoparticles (AgNPs) decorated zinc oxide/silicon (ZnO/Si) heterostructured nanomace arrays. They were prepared by two steps: (1) Si nanoneedles were grafted onto ZnO nanorod arrays via a catalyst-assisted vapor-liquid-solid (VLS) growth mechanism. (2) AgNPs were rapidly immobilized on the surface of nanomaces by a facile galvanic displacement reaction. The fabricated substrates were employed to detect rhodamine 6G (R6G) with a detection limit down to 10(-16) M, and exhibited a high-enhanced performance (enhancement factor (EF) as high as 8.7 × 10(7)). To illustrate the potential value of the prepared substrates, the different concentrations of melamine aqueous solution (from 10(-4) to 10(-10) M) were detected, and a quantitative relationship between the SERS spectrum intensity and the melamine concentration had been established. In addition, the measure of melamine residual in pure milk was carried out successfully, and the results indicated that the prepared 3D nanomace substrates had great potential in food inspection, environment protection, and a few other technologically important fields. PMID:25731067

  16. Optical anisotropy of GaSb type-II nanorods on vicinal (111)B GaAs

    SciTech Connect

    Kawazu, Takuya; Noda, Takeshi; Mano, Takaaki; Sakuma, Yoshiki; Akiyama, Yoshihiro; Sakaki, Hiroyuki

    2011-12-05

    We form self-assembled GaSb type-II nanorods on a vicinal (111)B GaAs substrate by molecular beam epitaxy and study their optical anisotropy. The GaSb nanorods are elongated and aligned along the [-1 0 1] direction, where the average length, width, and height are about 84, 30, and 2.5 nm. In polarized photoluminescence (PL) measurements, the peak of the GaSb nanorods is observed at about 1.1 eV, where the PL intensity is largest for the [-1 0 1] polarization and smallest for the polarization perpendicular to it. The degree of polarization is more than 20% and depends on the recombination energy. By comparing with a theoretical model based on 4 x 4 Luttinger-Kohn Hamiltonian, we find that the experimental results are explained by considering the Sb/As inter-diffusion and the nanorod height distribution.

  17. Mesoporous titania-vertical nanorod films with interfacial engineering for high performance dye-sensitized solar cells.

    PubMed

    Ahmed, Irfan; Fakharuddin, Azhar; Wali, Qamar; Bin Zainun, Ayib Rosdi; Ismail, Jamil; Jose, Rajan

    2015-03-13

    Working electrode (WE) fabrication offers significant challenges in terms of achieving high-efficiency dye-sensitized solar cells (DSCs). We have combined the beneficial effects of vertical nanorods grown on conducting glass substrate for charge transport and mesoporous particles for dye loading and have achieved a high photoconversion efficiency of (η) > 11% with an internal quantum efficiency of ∼93% in electrode films of thickness ∼7 ± 0.5 μm. Controlling the interface between the vertical nanorods and the mesoporous film is a crucial step in attaining high η. We identify three parameters, viz., large surface area of nanoparticles, increased light scattering of the nanorod-nanoparticle layer, and superior charge transport of nanorods, that simultaneously contribute to the improved photovoltaic performance of the WE developed. PMID:25687409

  18. The effect of growth temperature of seed layer on the structural and optical properties of ZnO nanorods

    NASA Astrophysics Data System (ADS)

    Gautam, Khyati; Singh, Inderpreet; Bhatnagar, P. K.; Peta, Koteswara Rao

    2016-05-01

    The structural and optical properties of ZnO nanorods are investigated as a function of growth temperature of the seed layer. The seed layer comprising of ZnO nanocrystallites is grown on ITO substrates at five different temperatures (150-550 °C) and the nanorods are grown on the seed layer by the facile hydrothermal method. The seed layer grown at 350 °C is observed to be uniformly textured with c-axis orientation leading to the synthesis of vertically aligned nanorods with smaller diameter. The HR-TEM analysis and the intense peak along (002) direction in the XRD spectra of this sample implied that the nanorods possess c-axis orientation. An enhanced UV emission is also observed in the photoluminescence spectra of this sample. The diversity in the morphology and orientation of the seeds at different temperatures has been explained by the growth kinetics of the ZnO nanocrystallites.

  19. Two-stage epitaxial growth of vertically-aligned SnO2 nano-rods on(001) ceria

    DOE PAGESBeta

    Solovyov, Vyacheslav F.; Wu, Li-jun; Rupich, Martin W.; Sathyamurthy, Srivatsan; Li, Xiaoping; Li, Qiang

    2014-09-20

    Growth of high-aspect ratio oriented tin oxide, SnO2, nano-rods is complicated by a limited choice of matching substrates. We show that a (001) cerium oxide, CeO2, surface uniquely enables epitaxial growth of tin-oxide nano-rods via a two-stage process. First, (100) oriented nano-wires coat the ceria surface by lateral growth, forming a uniaxially-textured SnO2 deposit. Second, vertical SnO2nano-rods nucleate on the deposit by homoepitaxy. We demonstrate growth of vertically oriented 1-2 μm long nano-rods with an average diameter of ≈20 nm.

  20. Two-stage epitaxial growth of vertically-aligned SnO2 nano-rods on (001) ceria

    SciTech Connect

    Solovyov, VF; Wu, LJ; Rupich, MW; Sathyamurthy, S; Li, XP; Li, Q

    2014-12-15

    Growth of high-aspect ratio oriented tin oxide, SnO2, nano-rods is complicated by a limited choice of matching substrates. We show that a (001) cerium oxide, CeO2, surface uniquely enables epitaxial growth of tin-oxide nano-rods via a two-stage process. First, (100) oriented nano-wires coat the ceria surface by lateral growth, forming a uniaxially-textured SnO2 deposit. Second, vertical SnO2 nano-rods nucleate on the deposit by homoepitaxy. We demonstrate growth of vertically oriented 1-2 mu m long nano-rods with an average diameter of approximate to 20 nm. 2014 Elsevier B.V. All rights reserved.

  1. Physiological investigation of gold nanorods toward watermelon.

    PubMed

    Wan, Yujie; Li, Junli; Ren, Hongxuan; Huang, Jin; Yuan, Hong

    2014-08-01

    The objective of the present study was to evaluate the phytotoxicity and oxidant stress of the gold nanorods toward watermelon, and hence give a quantitative risk assessment of both seeds and plants phase. The seed germination, the activity of antioxidant enzymes, and the contents of soluble protein and malondialdehyde (MDA) have been measured while the plant roots were observed by transmission electron microscopy (TEM). It was found that the gold nanorods significantly promoted the root elongation. Furthermore, the results on the enzymes activities of plant indicated that oxidative stress happened in the plant treated with gold nanorods. However, the gold nanorods resulted in the phytotoxicity toward plant especially at high concentration. The TEM images of the plant roots with and without the treatment of gold nanorods showed the significant different size of starch granules. In conclusion, significant physiological changes of plant occurred after treatment with the gold nanorods. PMID:25936063

  2. Multi-component nanorods for vaccination applications

    NASA Astrophysics Data System (ADS)

    Salem, A. K.; Hung, C. F.; Kim, T. W.; Wu, T. C.; Searson, P. C.; Leong, K. W.

    2005-04-01

    Immune responses from Au/Ni nanorods prepared by electrochemical deposition in alumina templates are evaluated in C57BL/6 mice. When the nanorods are bombarded into skin, they generate a strong CD8 T-cell and antibody response. When pcDNA3 is bound to the Ni segment of the nanorod, it provides a strong immunostimulatory adjuvant effect to the antigen bound on the Au segment.

  3. Hierarchical organization and molecular diffusion in gold nanorod/silica supercrystal nanocomposites.

    PubMed

    Hamon, Cyrille; Sanz-Ortiz, Marta N; Modin, Evgeny; Hill, Eric H; Scarabelli, Leonardo; Chuvilin, Andrey; Liz-Marzán, Luis M

    2016-04-14

    Hierarchical organization of gold nanorods was previously obtained on a substrate, allowing precise control over the morphology of the assemblies and macroscale spatial arrangement. Herein, a thorough description of these gold nanorod assemblies and their orientation within supercrystals is presented together with a sol-gel technique to protect the supercrystals with mesoporous silica films. The internal organization of the nanorods in the supercrystals was characterized by combining focused ion beam ablation and scanning electron microscopy. A mesoporous silica layer is grown both over the supercrystals and between the individual lamellae of gold nanorods inside the structure. This not only prevented the detachment of the supercrystal from the substrate in water, but also allowed small molecule analytes to infiltrate the structure. These nanocomposite substrates show superior Raman enhancement in comparison with gold supercrystals without silica owing to improved accessibility of the plasmonic hot spots to analytes. The patterned supercrystal arrays with enhanced optical and mechanical properties obtained in this work show potential for the practical implementation of nanostructured devices in spatially resolved ultradetection of biomarkers and other analytes. PMID:26961684

  4. Single inorganic-organic hybrid photovoltaic nanorod

    NASA Astrophysics Data System (ADS)

    Yoo, Sang-Hoon; Liu, Lichun; Ku, Tea-Woong; Hong, Soonchang; Whang, Dongmok; Park, Sungho

    2013-09-01

    We demonstrate that single photovoltaic (PV) nanorods can be readily fabricated by electrochemical processing in solution-phase under ambient conditions. A porous Au nanorod electrode in the core of the PV nanorod was central to both its structural formation and superior performance. We examined an intrinsically conducting polymer (polypyrrole) and an inorganic semiconductor (cadmium selenide) as precursor materials. Through an extremely simple and cost-effective fashioning process (solution-phase, room temperature), unadorned PV nanorods with up to 1.1% power conversion efficiency were obtained.

  5. Zinc oxide nanorod based photonic devices: recent progress in growth, light emitting diodes and lasers.

    PubMed

    Willander, M; Nur, O; Zhao, Q X; Yang, L L; Lorenz, M; Cao, B Q; Zúñiga Pérez, J; Czekalla, C; Zimmermann, G; Grundmann, M; Bakin, A; Behrends, A; Al-Suleiman, M; El-Shaer, A; Che Mofor, A; Postels, B; Waag, A; Boukos, N; Travlos, A; Kwack, H S; Guinard, J; Le Si Dang, D

    2009-08-19

    Zinc oxide (ZnO), with its excellent luminescent properties and the ease of growth of its nanostructures, holds promise for the development of photonic devices. The recent advances in growth of ZnO nanorods are discussed. Results from both low temperature and high temperature growth approaches are presented. The techniques which are presented include metal-organic chemical vapour deposition (MOCVD), vapour phase epitaxy (VPE), pulse laser deposition (PLD), vapour-liquid-solid (VLS), aqueous chemical growth (ACG) and finally the electrodeposition technique as an example of a selective growth approach. Results from structural as well as optical properties of a variety of ZnO nanorods are shown and analysed using different techniques, including high resolution transmission electron microscopy (HR-TEM), scanning electron microscopy (SEM), photoluminescence (PL) and cathodoluminescence (CL), for both room temperature and for low temperature performance. These results indicate that the grown ZnO nanorods possess reproducible and interesting optical properties. Results on obtaining p-type doping in ZnO micro- and nanorods are also demonstrated using PLD. Three independent indications were found for p-type conducting, phosphorus-doped ZnO nanorods: first, acceptor-related CL peaks, second, opposite transfer characteristics of back-gate field effect transistors using undoped and phosphorus doped wire channels, and finally, rectifying I-V characteristics of ZnO:P nanowire/ZnO:Ga p-n junctions. Then light emitting diodes (LEDs) based on n-ZnO nanorods combined with different technologies (hybrid technologies) are suggested and the recent electrical, as well as electro-optical, characteristics of these LEDs are shown and discussed. The hybrid LEDs reviewed and discussed here are mainly presented for two groups: those based on n-ZnO nanorods and p-type crystalline substrates, and those based on n-ZnO nanorods and p-type amorphous substrates. Promising electroluminescence

  6. Transmission Electron Microscopy Study of InN Nanorods

    SciTech Connect

    Liliental-Weber, Z.; Li, X.; Kryliouk, Olga; Park, H.J.; Mangum,J.; Anderson, T.

    2006-07-13

    InN nanorods were grown on a, c-, and r-plane of sapphire and also on Si (111) and GaN (0001) by non-catalytic, template-free hydride metal-organic vapor phase epitaxy and studied by transmission electron microscopy, electron energy loss (EELS) and photoluminescence (PL) at room temperature. These nanocrystals have different shapes and different faceting depending on the substrate used and their crystallographic orientation. EELS measurements have confirmed the high purity of these crystals. The observed PL peak was in the range of 0.9-0.95 eV. The strongest PL intensity was observed for the nanocrystals with the larger diameters.

  7. Graded core/shell semiconductor nanorods and nanorod barcodes

    DOEpatents

    Alivisatos, A. Paul; Scher, Erik C.; Manna, Liberato

    2009-05-19

    Disclosed herein is a graded core/shell semiconductor nanorod having at least a first segment of a core of a Group II-VI, Group III-V or a Group IV semiconductor, a graded shell overlying the core, wherein the graded shell comprises at least two monolayers, wherein the at least two monolayers each independently comprise a Group II-VI, Group III-V or a Group IV semiconductor.

  8. Sputtering nickel-molybdenum nanorods as an excellent hydrogen evolution reaction catalyst

    NASA Astrophysics Data System (ADS)

    Zhang, Li; Xiong, Kun; Nie, Yao; Wang, Xiaoxue; Liao, Jianhua; Wei, Zidong

    2015-11-01

    We report a novel fabrication of nickel-molybdenum alloy nanorods catalyst for hydrogen evolution reaction (HER), which is prepared by co-deposition of pure nickel and molybdenum in a multisource sputtering system on the surface of Ni foam substrate. The Ni-Mo alloy film exhibits favorable vertical nanorods structure and presents the most efficient activity for HER compared to the film only including one metal element. The remarkably enhanced catalytic activity is attributed to its ordered array geometry as well as the synergistic interaction between Ni and Mo. Meanwhile, the open space within nanorod arrays facilitates the electrolyte penetration and diffusion of ionic species, allowing high utilization efficiency of active species as well as rapidly release of evolved hydrogen gas from the electrode surface.

  9. Enhanced Photocatalytic Performance Using One Dimensional Ordered TiO2 Nanorods Modified by Graphene Oxide.

    PubMed

    Huang, Jinzhao; Fu, Ke; Yao, Nannan; Deng, Xiaolong; Ding, Meng; Shao, Minghui; Xu, Xijin; Wei, Mingzhi

    2016-02-01

    A new architecture of one dimensional ordered TiO2 nanorods modified by graphene oxide (GO) was assembled. The GO as the higher carrier mobility can reduce the recombination of carriers, which is more favourable for the methy orange (MO) degradation. Incorporating GO with the unblocked passageway for carrier transportation of the TiO2 nanorods can separate the transport pathway of electron and hole effectively. Furthermore, the large surface areas of TiO2 nanorods grown on the GO are beneficial to the enhancement of photocatalytic properties, and the reasonable band energy level can be obtained for the architecture, which is favorable for enhancing carrier separation and transportation. Finally, the higher transparency of the structure can enhance the light absorption. The photocatalyst grown on FTO substrates makes it easier to collect and recycle. PMID:27433607

  10. Optical and ferromagnetic properties of Cr doped ZnO nanorods

    NASA Astrophysics Data System (ADS)

    Lin, Bao-Zhu; Zhou, Lin; Yuldashev, Sh. U.; Fu, De-Jun; Kang, Tae-Won

    2014-10-01

    ZnO nanorods doped with 1-2 wt% Cr were grown on Si substrates by hydrothermal method. Scanning electron spectroscopy and X-ray diffraction show the hexagonal structure of the nanorods with ZnO oriented along (1 0 0), (0 0 2), (1 0 1) and (1 0 2) and CrO2 along (2 1 1). Ionized donor bound exciton, neutral donor bound exciton, free exciton, two-electron-satellite of hydrogen donor bound exciton, and donor acceptor pairs were observed in low temperature photoluminescence spectra. The photoluminescence spectra along with XPS results confirm that Zni was formed in the low temperature hydrothermal process. Superconducting quantum interference device measurement reveals that the Cr-doped ZnO nanorods are ferromagnetic with saturation magnetization of 2.421 × 10-3 emu/g. The room temperature ferromagnetic properties are explained by defect-mediated bound magnetic polarons based on Zni.

  11. Synthesis and photoluminescence of quasi-arrayed ZnMgO nanorods

    NASA Astrophysics Data System (ADS)

    Wang, Fazhan; Zhao, Chao; Liu, Bo; Yuan, Sicong

    2009-06-01

    Quasi-arrayed ZnMgO single-crystal nanorods with different Mg concentrations have been fabricated by thermal evaporation of Zn and Mg on a Si substrate using Au as a catalyst. The synthesized ZnMgO nanorods had uniform flat hexagonal crystallorgraphic planes with diameters of about 300 nm. It was found that with the increase in the dopant concentration, the peak position of (0 0 2) was shifted towards the high-angle side (from 34.40° to 34. 54°) and the near-band-edge emission was blue-shifted to 364 nm (3.41 eV) from 385 nm (3.22 eV) in comparison with that of pure ZnO. The direct modulation of the band-gap caused by Mg substitution was responsible for the blue shift. The possible growth mechanism of the ZnMgO nanorods was discussed.

  12. Synthesis and characterization of quasi-aligned ZnCdO nanorods

    NASA Astrophysics Data System (ADS)

    Wang, F. Z.; Ye, Z. Z.; Ma, D. W.; Zhu, L. P.; Zhuge, F.; He, H. P.

    2005-10-01

    Quasi-aligned ZnCdO single-crystal nanorods were prepared for the first time by using thermal evaporation of Zn and CdCl2 on a Si substrate with the presence of Au catalyst. The maximum Cd content was up to about 16.7at.%, which was significantly larger than the thermodynamic solid solubility limits. The ZnCdO nanorods have uniform flat hexagonal crystallographic planes with diameters of about 150nm. Notably, with the Cd content increasing, the ultraviolet near-band-edge emission was redshifted to 407nm(3.04eV ) from 386nm(3.21eV). The direct modulation of the band gap caused by Cd substitution is responsible for the redshift. The possible growth mechanism of the ZnCdO nanorods was discussed.

  13. Ag/ZnO heterostructures and their photocatalytic activity under visible light: effect of reducing medium.

    PubMed

    Liu, Yangsi; Wei, Shanghai; Gao, Wei

    2015-04-28

    Decoration of ZnO by Ag is a promising method to improve its photocatalytic activity and extend the photoreactivity to the visible light. In this paper, Ag/ZnO heterostructures have been synthesised by photoreduction in various reducing mediums. When the Ag/ZnO nanocomposite arrays were obtained in the air, only a small amount of Ag was reduced. Ag nanosheets and nanoparticles were formed in the water and attached on the top and side surfaces of ZnO nanorods, forming Ag/ZnO heterostructures with a nano(sheet-rod-particle) multi-level structure. In the mixture of water and ethanol, a large amount of Ag nanoclusters was produced and embedded in the ZnO nanorod arrays. The influence of reducing mediums on the microstructure, morphology, quantity and dispersion of Ag nanostructures was investigated; and the effect of Ag component on the optical properties and visible light driven photocatalytic behaviour of the Ag/ZnO heterostructures was discussed. PMID:25621832

  14. Strong photonic crystal behavior in regular arrays of core-shell and quantum disc InGaN/GaN nanorod light-emitting diodes

    SciTech Connect

    Lewins, C. J. Le Boulbar, E. D.; Lis, S. M.; Shields, P. A.; Allsopp, D. W. E.; Edwards, P. R.; Martin, R. W.

    2014-07-28

    We show that arrays of emissive nanorod structures can exhibit strong photonic crystal behavior, via observations of the far-field luminescence from core-shell and quantum disc InGaN/GaN nanorods. The conditions needed for the formation of directional Bloch modes characteristic of strong photonic behavior are found to depend critically upon the vertical shape of the nanorod sidewalls. Index guiding by a region of lower volume-averaged refractive index near the base of the nanorods creates a quasi-suspended photonic crystal slab at the top of the nanorods which supports Bloch modes. Only diffractive behavior could be observed without this region. Slab waveguide modelling of the vertical structure shows that the behavioral regime of the emissive nanorod arrays depends strongly upon the optical coupling between the nanorod region and the planar layers below. The controlled crossover between the two regimes of photonic crystal operation enables the design of photonic nanorod structures formed on planar substrates that exploit either behavior depending on device requirements.

  15. Electrical and hydrogen-sensing characteristics of field effect transistors based on nanorods of ZnO and WO2.72.

    PubMed

    Rout, Chandra Sekhar; Kulkarni, G U; Rao, C N R

    2009-09-01

    Top-gated field effect transistors (FETs) using Au-gap (5 microm) electrodes on glass substrate and SiO2/Si as gate have been fabricated with undoped and doped nanorods of ZnO as well as with WO2.72 nanorods as active semiconductor elements. The I-V characteristics at different gate voltages show that the nanorods are n-type semiconductors and the derived transfer characteristics show that the FET devices function in the depletion mode. Al-doping (3 at%) enhances the carrier mobility of ZnO nanorods to 128.6 cm2/V x s as against to 0.009 cm2/V x s estimated in the case of the undoped nanorods. Doping with Cd and Mg (3 at%) as well as N (approximately 1 at%) similarly increases the mobility although to a smaller extent. The Cd-doped ZnO nanorods exhibit the high sensitivity (defined as the ratio of the resistance in air to that in the hydrogen) (20) for 1000 ppm of hydrogen. Application of gate voltage decreases the recovery times of the nanorod sensors. FETs based on WO2.72 nanorods also show the depletion mode type characteristics and a carrier mobility of 8.38 cm2/V x s is obtained. The WO2.72 based FETs exhibit good sensitivity (approximately 10) for 1000 ppm hydrogen. PMID:19928282

  16. Influence of Y-doped induced defects on the optical and magnetic properties of ZnO nanorod arrays prepared by low-temperature hydrothermal process

    PubMed Central

    2012-01-01

    One-dimensional pure zinc oxide (ZnO) and Y-doped ZnO nanorod arrays have been successfully fabricated on the silicon substrate for comparison by a simple hydrothermal process at the low temperature of 90°C. The Y-doped nanorods exhibit the same c-axis-oriented wurtzite hexagonal structure as pure ZnO nanorods. Based on the results of photoluminescence, an enhancement of defect-induced green-yellow visible emission is observed for the Y-doped ZnO nanorods. The decrease of E2(H) mode intensity and increase of E1(LO) mode intensity examined by the Raman spectrum also indicate the increase of defects for the Y-doped ZnO nanorods. As compared to pure ZnO nanorods, Y-doped ZnO nanorods show a remarked increase of saturation magnetization. The combination of visible photoluminescence and ferromagnetism measurement results indicates the increase of oxygen defects due to the Y doping which plays a crucial role in the optical and magnetic performances of the ZnO nanorods. PMID:22768847

  17. Selective growth of hierarchical ZnO nanorod arrays on the graphene nanosheets

    NASA Astrophysics Data System (ADS)

    Yang, Hui; Li, Lan; Li, Jinliang; Mo, Zhaojun

    2016-01-01

    We report directly selective-area grown (SAG) high-quality hierarchical ZnO nanorod arrays on the graphene nanosheets without invoking damage or introducing a catalyst. The SAG behavior in the non-catalytic growth mechanism is attributed to dangling bonds on the boundary edges of graphene nanosheets, which serve as the preferential adsorption and nucleation sites of ZnO nanorod. High densities of hierarchical ZnO nanorods show single-crystalline hexagonal wurtzite structure and are vertically well-aligned on the graphene nanosheets, with the diameter and the density strongly dependent on the growth temperature. Furthermore, no carbon impurity can be seen in the tips of the ZnO nanorods and also no carbon-related defect peak in the 10 K PL spectrum of ZnO nanorods. Our approach using a graphene-nanosheet substrate provides an efficient route for the growth of high-quality ZnO with a one-dimensional (1D) hierarchical nanostructure, which is highly desirable for fabricating 1D ZnO hybrid optoelectronic devices, particularly for a fast-response UV photodetector and highly-sensitive gas sensor.

  18. Deterministic assembly of linear gold nanorod chains as a platform for nanoscale applications.

    PubMed

    Rey, Antje; Billardon, Guillaume; Lörtscher, Emanuel; Moth-Poulsen, Kasper; Stuhr-Hansen, Nicolai; Wolf, Heiko; Bjørnholm, Thomas; Stemmer, Andreas; Riel, Heike

    2013-09-21

    We demonstrate a method to assemble gold nanorods highly deterministically into a chain formation by means of directed capillary assembly. This way we achieved straight chains consisting of end-to-end aligned gold nanorods assembled in one specific direction with well-controlled gaps of ∼6 nm between the individual constituents. We determined the conditions for optimum quality and yield of nanorod chain assembly by investigating the influence of template dimensions and assembly temperature. In addition, we transferred the gold nanorod chains from the assembly template onto a Si/SiO2 target substrate, thus establishing a platform for a variety of nanoscale electronic and optical applications ranging from molecular electronics to optical and plasmonic devices. As a first example, electrical measurements are performed on contacted gold nanorod chains before and after their immersion in a solution of thiol end-capped oligophenylenevinylene molecules showing an increase in the conductance by three orders of magnitude, indicating molecular-mediated transport. PMID:23900232

  19. Impact of the nanorod structure on the tandem thin-film solar cell.

    PubMed

    Tang, M; Chang, S T; Huang, C-X; Liu, Y T; Chen, Y H

    2011-07-01

    The novel thin-film solar cell was investigated with a nanorod structure that could solve the conflict between light absorption and carrier transport in the amorphous silicon (a-Si)/amorphous silicon-germanium (a-SiGe) tandem thin-film solar cell. This structure has an n-type a-Si nanorod array on the substrate, and an a-SiOx p-layer and an a-SiGe i-layer are sequentially grown along the surface of each n-type a-Si nanorod, for the bottom cell. After the above bottom-cell process, a similar process is used to fabricate an amorphous Si p-i-n top cell on the bottom cell. Under sunlight illumination, the light is absorbed along the vertical direction of the nanorod, but as the carrier transport is along the horizontal direction, the nanorod may absorb most of the sunlight. In the meantime, the solar cell is still thin enough for the effective transport of photogenerated carriers. PMID:22121598

  20. Local structural properties of Co-ion-implanted ZnO nanorods

    NASA Astrophysics Data System (ADS)

    Park, C. I.; Jin, Zhenlan; Jeong, E. S.; Hwang, I. H.; Han, S. W.

    2013-12-01

    We examined the local structural properties around Co and Zn ions in Co-ion-implanted ZnO nanorods by using an X-ray absorption fine structure (XAFS) analysis. Vertically-aligned ZnO nanorods were synthesized on Al2O3 substrates by using a catalyst-free metal-organic chemicalvapor deposition. Co ions (Co+ and Co2+) with energies of 50 and 100 keV and fluxes of 1013 and 1015 particles/cm2 were implanted in the ZnO nanorods, and the ion-implanted ZnO nanorods were annealed at 400-650°C. X-ray absorption near edge structure (XANES) analyses demonstrated that the chemical valence state of the Co ions were mostly 2+. An extended XAFS (EXAFS) analysis revealed that the Co ions were mostly substituted at the Zn sites of ZnO nanorods at a Coion flux of 1015 particles/cm2. However, at a flux of 1013 particles/cm2, Co ions formed Co-O and Co-Co clusters. These results were in contrast to the Co distribution in Co-added ZnO predicted by using a Monte Carlo method.

  1. Hydrothermally Processed Photosensitive Field-Effect Transistor Based on ZnO Nanorod Networks

    NASA Astrophysics Data System (ADS)

    Kumar, Ashish; Bhargava, Kshitij; Dixit, Tejendra; Palani, I. A.; Singh, Vipul

    2016-07-01

    Formation of a stable, reproducible zinc oxide (ZnO) nanorod-network-based photosensitive field-effect transistor using a hydrothermal process at low temperature has been demonstrated. K2Cr2O7 additive was used to improve adhesion and facilitate growth of the ZnO nanorod network over the SiO2/Si substrate. Transistor characteristics obtained in the dark resemble those of the n-channel-mode field-effect transistor (FET). The devices showed I on/I off ratio above 8 × 102 under dark condition, field-effect mobility of 4.49 cm2 V-1 s-1, and threshold voltage of -12 V. Further, under ultraviolet (UV) illumination, the FET exhibited sensitivity of 2.7 × 102 in off-state (-10 V) versus 1.4 in on-state (+9.7 V) of operation. FETs based on such nanorod networks showed good photoresponse, which is attributed to the large surface area of the nanorod network. The growth temperature for ZnO nanorod networks was kept at 110°C, enabling a low-temperature, cost-effective, simple approach for high-performance ZnO-based FETs for large-scale production. The role of network interfaces in the FET performance is also discussed.

  2. Beam Divergence and Thermal Transient Characteristics of InGaN/GaN Light Emitting Diodes with Rear Side Grown ZnO Nanorods

    NASA Astrophysics Data System (ADS)

    Jin, Joo; Deul Ryu, Beo; Han, Min; Saravana Kumar, R.; Uthirakumar, Periyayya; Kim, Hyun Kyu; Jong Han, Yang; Lee, Kyu Han; Hong, Chang-Hee

    2012-10-01

    We report the enhanced light output power of InGaN/GaN light-emitting diodes (LEDs) with ZnO nanorods grown on the polished rear side of the sapphire substrate. ZnO seeds were spin coated on the polished bottom side of the sapphire substrate and a simple solution technique was employed to grow ZnO nanorods. Results reveal that the rear side grown ZnO nanorods enhance the light output power of the GaN LEDs significantly due to the light wave guiding and reflectivity of ZnO nanorods. The light output power from the GaN LED with rear side grown ZnO nanorods was 15% higher than that of a conventional LED. Thermal conductivity characteristics showed that GaN LEDs with ZnO nanorods possess low thermal resistance (25.1 °C/W) compared to the conventional LEDs (40.5 °C/W) because of high thermal conductivity of ZnO nanorods.

  3. Sputtered highly ordered TiO2 nanorod arrays and their applications as the electrode in dye-sensitized solar cells.

    PubMed

    Meng, Lijian; Ma, Aifeng; Ying, Pinliang; Feng, Zhaochi; Li, Can

    2011-02-01

    For the first time, the TiO2 nanorod arrays have been prepared on ITO substrates at room temperature by dc reactive magnetron sputtering technique. These TiO2 nanorods have a preferred orientation along the (220) direction and are perpendicular to the ITO substrate. Both the X-ray diffraction and Raman scattering measurements show that the highly ordered TiO2 nanorod arrays have an anatase crystal structure. The diameter of the nanorod varies from 30 nm to 100 nm and the nanorod length can be varied from several hundred nanometers to several micrometers depending on the deposition time. The TiO2 nanorod arrays with about 3 micrometers length have been used as an electrode for dye-sensitized solar cell (DSSC). Short-circuit photocurrent density, open-circuit voltage, fill factor and light-to-electricity conversion efficiency at 100 mW/cm2 light intensity are estimated to be 12.76 mA/cm2, 0.65 V, 0.63 and 5.25%, respectively, for the DSSC made of the TiO2 nanorods. PMID:21456121

  4. Indirect Determination of Mercury Ion by Inhibition of a Glucose Biosensor Based on ZnO Nanorods

    PubMed Central

    Chey, Chan Oeurn; Ibupoto, Zafar Hussain; Khun, Kimleang; Nur, Omer; Willander, Magnus

    2012-01-01

    A potentiometric glucose biosensor based on immobilization of glucose oxidase (GOD) on ZnO nanorods (ZnO-NRs) has been developed for the indirect determination of environmental mercury ions. The ZnO-NRs were grown on a gold coated glass substrate by using the low temperature aqueous chemical growth (ACG) approach. Glucose oxidase in conjunction with a chitosan membrane and a glutaraldehyde (GA) were immobilized on the surface of the ZnO-NRs using a simple physical adsorption method and then used as a potentiometric working electrode. The potential response of the biosensor between the working electrode and an Ag/AgCl reference electrode was measured in a 1mM phosphate buffer solution (PBS). The detection limit of the mercury ion sensor was found to be 0.5 nM. The experimental results provide two linear ranges of the inhibition from 0.5 × 10−6 mM to 0.5 × 10−4 mM, and from 0.5 × 10−4 mM to 20 mM of mercury ion for fixed 1 mM of glucose concentration in the solution. The linear range of the inhibition from 10−3 mM to 6 mM of mercury ion was also acquired for a fixed 10 mM of glucose concentration. The working electrode can be reactivated by more than 70% after inhibition by simply dipping the used electrode in a 10 mM PBS solution for 7 min. The electrodes retained their original enzyme activity by about 90% for more than three weeks. The response to mercury ions was highly sensitive, selective, stable, reproducible, and interference resistant, and exhibits a fast response time. The developed glucose biosensor has a great potential for detection of mercury with several advantages such as being inexpensive, requiring minimum hardware and being suitable for unskilled users. PMID:23202200

  5. Indirect determination of mercury ion by inhibition of a glucose biosensor based on ZnO nanorods.

    PubMed

    Chey, Chan Oeurn; Ibupoto, Zafar Hussain; Khun, Kimleang; Nur, Omer; Willander, Magnus

    2012-01-01

    A potentiometric glucose biosensor based on immobilization of glucose oxidase (GOD) on ZnO nanorods (ZnO-NRs) has been developed for the indirect determination of environmental mercury ions. The ZnO-NRs were grown on a gold coated glass substrate by using the low temperature aqueous chemical growth (ACG) approach. Glucose oxidase in conjunction with a chitosan membrane and a glutaraldehyde (GA) were immobilized on the surface of the ZnO-NRs using a simple physical adsorption method and then used as a potentiometric working electrode. The potential response of the biosensor between the working electrode and an Ag/AgCl reference electrode was measured in a 1mM phosphate buffer solution (PBS). The detection limit of the mercury ion sensor was found to be 0.5 nM. The experimental results provide two linear ranges of the inhibition from 0.5 × 10(-6) mM to 0.5 × 10(-4) mM, and from 0.5 × 10(-4) mM to 20 mM of mercury ion for fixed 1 mM of glucose concentration in the solution. The linear range of the inhibition from 10(-3) mM to 6 mM of mercury ion was also acquired for a fixed 10 mM of glucose concentration. The working electrode can be reactivated by more than 70% after inhibition by simply dipping the used electrode in a 10 mM PBS solution for 7 min. The electrodes retained their original enzyme activity by about 90% for more than three weeks. The response to mercury ions was highly sensitive, selective, stable, reproducible, and interference resistant, and exhibits a fast response time. The developed glucose biosensor has a great potential for detection of mercury with several advantages such as being inexpensive, requiring minimum hardware and being suitable for unskilled users. PMID:23202200

  6. Nucleation and growth of GaN nanorods on Si (111) surfaces by plasma-assisted molecular beam epitaxy - The influence of Si- and Mg-doping

    SciTech Connect

    Furtmayr, Florian; Vielemeyer, Martin; Stutzmann, Martin; Eickhoff, Martin; Arbiol, Jordi

    2008-08-01

    The self-assembled growth of GaN nanorods on Si (111) substrates by plasma-assisted molecular beam epitaxy under nitrogen-rich conditions is investigated. An amorphous silicon nitride layer is formed in the initial stage of growth that prevents the formation of a GaN wetting layer. The nucleation time was found to be strongly influenced by the substrate temperature and was more than 30 min for the applied growth conditions. The observed tapering and reduced length of silicon-doped nanorods is explained by enhanced nucleation on nonpolar facets and proves Ga-adatom diffusion on nanorod sidewalls as one contribution to the axial growth. The presence of Mg leads to an increased radial growth rate with a simultaneous decrease of the nanorod length and reduces the nucleation time for high Mg concentrations.

  7. The fate of silver ions in the photochemical synthesis of gold nanorods: an extended X-ray absorption fine structure analysis.

    PubMed

    Giannici, Francesco; Placido, Tiziana; Curri, Maria Lucia; Striccoli, Marinella; Agostiano, Angela; Comparelli, Roberto

    2009-12-14

    Water-soluble gold nanorods (Au NRs) were synthesized using a silver-ion mediated photochemical route under UV irradiation. Extended X-ray Absorption Fine Structure (EXAFS) measurements on the Ag K-edge were performed on samples obtained at different Ag/Au ratios and at increasing irradiation times in order to investigate the fate of silver ions during the growth of Au NRs. EXAFS measurements allowed to probe the chemical state and the local environment of silver in the final product. Experimental data suggest that Ag atoms are placed on top of the Au particles as metallic Ag(0), while no significant contribution to the EXAFS spectra comes from AgBr or other Ag(+) based species. The reported results strongly support the deposition of Ag(0) islands on the (110) surfaces of the Au particles, thus driving the anisotropic growth via the (111) surfaces. PMID:19921074

  8. Morphology-dependent bactericidal activities of Ag/CeO2 catalysts against Escherichia coli.

    PubMed

    Wang, Lian; He, Hong; Yu, Yunbo; Sun, Li; Liu, Sijin; Zhang, Changbin; He, Lian

    2014-06-01

    Silver-loaded CeO2 nanomaterials (Ag/CeO2) including Ag/CeO2 nanorods, nanocubes, nanoparticles were prepared with hydrothermal and impregnation methods. Catalytic inactivation of Escherichia coli with Ag/CeO2 catalysts through the formation of reactive oxygen species (ROS) was investigated. For comparison purposes, the bactericidal activities of CeO2 nanorods, nanocubes and nanoparticles were also studied. There was a 3-4 log order improvement in the inactivation of E. coli with Ag/CeO2 catalysts compared with CeO2 catalysts. Temperature-programmed reduction of H2 showed that Ag/CeO2 catalysts had higher catalytic oxidation ability than CeO2 catalysts, which was the reason for that Ag/CeO2 catalysts exhibited stronger bactericidal activities than CeO2 catalysts. Further, the bactericidal activities of CeO2 and Ag/CeO2 depend on their shapes. Results of 5,5-dimethyl-1-pyrroline-N-oxide spin-trapping measurements by electron spin resonance and addition of catalase as a scavenger indicated the formation of OH, O2(-), and H2O2, which caused the obvious bactericidal activity of catalysts. The stronger chemical bond between Ag and CeO2 nanorods led to lower Ag(+) elution concentrations. The toxicity of Ag(+) eluted from the catalysts did not play an important role during the bactericidal process. Experimental results also indicated that Ag/CeO2 induced the production of intracellular ROS and disruption of the cell wall and cell membrane. A possible production mechanism of ROS and bactericidal mechanism of catalytic oxidation were proposed. PMID:24662462

  9. Interaction of phospholipid with silver nanorods

    NASA Astrophysics Data System (ADS)

    Anju, K. N.; Mahesh, S.; Kalarikkal, Nandakumar

    2014-01-01

    Development of a simple method for incorporating phospholipids onto the surfaces of anisotropic silver nanorods as a stepping-stone for creating responsive and multifunctional nanocomposites. 1, 2-distearoyl-sn-glycero-3-phosphatidylcholine (DSPC)-silver nanorod composites were prepared by immobilizing liposomes onto the surface of cetyltrimethylammonium bromide (CTAB) capped silver nanorods. Here we report the role of phospholipids to control the self assembly of silver nanorods into agglomerate architectures ranging from open "end-to-end" networks to densely packed "side-to-side" arrays. The tuning of electrostatic interactions within the phospholipid layers is governed to lipid silver nanorod assembly and also about the organization of phospholipid layers themselves around nanorod surfaces. The initial studies on passive lipid functionalized nanorods could serve as the groundwork for introducing active components into these systems to make more switchable or reconfigurable nanocomposite material. Changing the surface species on silver nanorods from CTAB to DSPC is reflected in ξ- potential measurements. The surface morphology is studied using SEM and TEM. The optical studies are carried out using UV-Vis spectroscopy.

  10. Role of Ag in the formation of interfacial intermetallic phases in Sn-Zn soldering

    NASA Astrophysics Data System (ADS)

    Song, Jenn-Ming; Liu, Pei-Chi; Shih, Chia-Ling; Lin, Kwang-Lung

    2005-09-01

    This study explored the effect of Ag as the substrate or alloying element of solders on the interfacial reaction in Sn-Zn soldering. Results show that instead of Ag-Sn compounds, ζ-AgZn and γ-Ag5Zn8 form at the Sn-Zn/Ag interface. The addition of Ag in Sn-Zn solders leads to the precipitation of ɛ-AgZn3 from the liquid solder on preformed interfacial intermetallics. The morphology of this additional AgZn3 is closely related to the solidification process of Ag-Zn intermetallics and the under intermetallic layer.

  11. Zinc Oxide Nanorod Based Ultraviolet Detectors with Wheatstone Bridge Design

    NASA Astrophysics Data System (ADS)

    Vasudevan, Arun

    This research work, for the first time, investigated metal semiconductor-metal (MSM) zine oxide (ZnO) nanorod based ultra-violet (UV) detectors having a Wheatstone bridge design with a high responsivity at room temperature and above, as well as a responsivity that was largely independent of the change in ambient conditions. The ZnO nanorods which acted as the sensing element of the detector were grown by a chemical growth technique. Studies were conducted to determine the effects on ZnO nanorod properties by varying the concentration of the chemicals used for the rod growth. These studies showed how the rod diameter and the deposition of ZnO nanorods from the solution was controlled by varying the concentration of the chemicals used for the rod growth. Conventional MSM UV detectors were fabricated with ZnO nanorods grown under optimized conditions to determine the dependence of UV response on electrode dimension and rod dimension. These studies gave insights into the dependence of UV response on the width of the electrode, spacing between the electrodes, density of the rod growth, and length and diameter of the rods. The UV responsivity was affected by varying the number of times the seed layer was spin coated, by varying the spin speed of seed layer coating and by varying the annealing temperature of the seed and rod. Based on these studies, optimum conditions for the fabrication of Wheatstone bridge UV ZnO nanorod detectors were determined. The Wheatstone bridge ZnO nanorod UV detectors were fabricated in three different configurations, namely, symmetric, asymmetric, and quasi-symmetric. The transient responses of the symmetric, asymmetric and quasi-symmetric configurations at room temperature and above showed how the response stability differed. At high temperature the responsivity of quasi-symmetric Wheatstone bridge detector configuration did not drop after saturation and the responsivity drifted by 17% to 25% from the room temperature response

  12. Gold nanorods grown on microgels leading to hexagonal nanostructures.

    PubMed

    Kumar, V R Rajeev; Samal, A K; Sreeprasad, T S; Pradeep, T

    2007-08-14

    Hexagonal patterns of gold nanorods were made by assembling gold nanorod-coated poly(N-isopropyl acrylamide) microgels. The required population of nanorods on the microgels was achieved by attaching nanoparticle seeds on the latter and growing them to nanorods. The various materials prepared were characterized by UV-vis spectroscopy and transmission electron microscopy. Similar experiments with nanoparticle-coated or prefabricated nanorod-coated microgels did not give such hexagonal patterns. We suggest that the interlocking of nanorods leads to these regular structures. This is the first report of a solution phase method for assembling nanorods into a hexagonal pattern. PMID:17637011

  13. Surfactant controlled synthesis of crystalline phosphovanadate nanorods

    SciTech Connect

    Asnani, Minakshi; Thomas, Jency; Sen, Prasenjit; Ramanan, Arunachalam . E-mail: aramanan@chemistry.iitd.ac.in

    2007-04-12

    Phosphovanadate nanorods were obtained in a reaction of vanadium (V) oxide as a precursor and a cationic surfactant, dodecylpyridinium chloride, as structure directing template at pH {approx}3 at room temperature. The composition and morphology of the nanorods was established by powder X-ray diffraction (XRD), energy dispersive X-ray analysis (EDAX), fourier transform infra-red spectroscopy (FTIR), thermogravimetric analysis (TGA), transmission electron microscopy (TEM) and atomic force microscopy (AFM). The obtained nanorods have diameters of 40-60 nm with lengths up to 1 {mu}m. The effect of reaction parameters such as concentration of surfactant and pH of the solution on the growth of nanorods has been investigated. A plausible mechanism involving the coalescence of nanoparticle 'seeds' leading to one-dimensional nanorods is also discussed. The same reaction when performed under hydrothermal condition, keeping other reaction parameters unchanged, resulted in the formation of phosphovanadate nanospheres of diameter 10-15 nm.

  14. Double Fano resonances in plasmon coupling nanorods

    NASA Astrophysics Data System (ADS)

    Liu, Fei; Jin, Jie

    2015-05-01

    Fano resonances are investigated in nanorods with symmetric lengths and side-by-side assembly. Single Fano resonance can be obtained by a nanorod dimer, and double Fano resonances are shown in nanorod trimers with side-by-side assembly. With transverse plasmon excitation, Fano resonances are caused by the destructive interference between a bright superradiant mode and dark subradiant modes. The bright mode originates from the electric plasmon resonance, and the dark modes originate from the magnetic resonances induced by near-field inter-rod coupling. Double Fano resonances result from double dark modes at different wavelengths, which are induced and tuned by the asymmetric gaps between the adjacent nanorods. Fano resonances show a high figure of merit and large light extinction in the periodic array of assembled nanorods, which can potentially be used in multiwavelength sensing in the visible and near-infrared regions.

  15. Facile synthesis of ZnO nanorod arrays and hierarchical nanostructures for photocatalysis and gas sensor applications.

    PubMed

    Ma, Shuaishuai; Li, Rong; Lv, Changpeng; Xu, Wei; Gou, Xinglong

    2011-08-30

    A facile one-step hydrothermal route was demonstrated to grow ZnO nanorod arrays and hierarchical nanostructures on arbitrary substrates without any catalysts and seeds coated before the reaction, which are prerequisite in the current two-step protocol. Meanwhile, ZnO nanoflowers composed of nanorods were obtained at the bottom of the autoclaves in the absence of substrates. An in situ spontaneous-seeds-assisted growth mechanism was tentatively proposed on the basis of the experimental data to explain the growth process of ZnO nanostructures. Moreover, the obtained ZnO nanorod arrays exhibited superior photocatalytic activity for decomposing methyl orange, and the nanoflowers showed better gas sensing performance towards some flammable gases and corrosive vapors with high sensitivity, rapid response-recovery characteristics, good selectivity and long-term stability. PMID:21684076

  16. Effect of lattice strain on structural and optical properties of ZnO nanorods grown by hydrothermal method

    NASA Astrophysics Data System (ADS)

    Gautam, Khyati; Singh, Inderpreet; Nirwal, Varun Singh; Singh, Joginder; Peta, Koteswara Rao; Bhatnagar, P. K.

    2016-05-01

    In this work, we have synthesized ZnO nanorods over ZnO seeds/ITO/glass substrate by the facile hydrothermal method. ZnO seeds are grown at different temperatures ranging from 150°C to 550°C in steps of 100°C. We have studied the effect of strain on the structural and optical properties of ZnOnanorods. It was observed that the growth temperature of seed layer has an influence over the lattice strain present in the nanorods. The as synthesized nanorods were characterized by scanning electron microscope (SEM), x-ray diffraction (XRD) and photoluminescence (PL). SEM images confirm the formation of dense arrays of vertically aligned nanorods on seeds which are grown at 350°C. In addition to this, XRD patterns reveal that these ZnO nanorods are preferentially oriented along (002) direction. The strain analysis based on the XRD results reveals that the minimum value of strain is obtained at 350°C which is attributed to the improved crystalline quality of the interface of seed layer and nanorods leading to their c-axis alignment and enhancement of ultraviolet emission as observed in the PL spectra.

  17. Optical parameters of boron-doped ZnO nanorods grown by low-temperature hydrothermal reaction.

    PubMed

    Kim, Soaram; Park, Hyunggil; Nam, Giwoong; Yoon, Hyunsik; Kim, Younggyu; Kim, Byunggu; Ji, Iksoo; Kim, Jong Su; Kim, Jin Soo; Kim, Do Yeob; Kim, Sung-O; Leem, Jae-Young

    2014-11-01

    Sol-gel spin-coating was used to deposit ZnO seed layers onto quartz substrates, and ZnO nanorods doped with various concentrations of B (i.e., BZO nanorods) ranging from 0 to 2.0 at% were hydrothermally grown on the ZnO seed layers. The effects of B doping on the absorption coefficient, optical band gap, Urbach energy, refractive index, extinction coefficient, single-oscillator energy, dispersion energy, average oscillator strength, average oscillator wavelength, dielectric constant, and optical conductivity of the hydrothermally grown BZO nanorods were investigated. The optical band gaps were 3.255, 3.243, 3.254, 3.258, and 3.228 eV for the nanorods grwon at 0, 0.5, 1.0, 1.5 and 2.0 at% B, respectively. B doping increased the Urbach energy from 40.7 to 65.1 meV for the nanorods grown at 0 and 2.0 at% B, respectively, and significantly affected the dispersion energy, the single-oscillator energy, the average oscillator wavelength, the average oscillator strength, the refractive index, and the optical conductivity of the hydrothermally grown BZO nanorods. PMID:25958555

  18. Electrochemical growth of ZnO nano-rods on polycrystalline Zn foil

    NASA Astrophysics Data System (ADS)

    Wong, M. H.; Berenov, A.; Qi, X.; Kappers, M. J.; Barber, Z. H.; Illy, B.; Lockman, Z.; Ryan, M. P.; MacManus-Driscoll, J. L.

    2003-09-01

    ZnO nano-rods were grown on polycrystalline Zn foil by cathodic electrodeposition in an aqueous zinc chloride/calcium chloride solution at 80°C. Variations in the solution concentration and substrate surface preparation were explored to shed light on the nucleation of the nano-rods. It was found that the nano-rod diameter increased with increasing solution concentration. Rolling striations and native ZnO on the surface of the Zn appeared to enhance nucleation and allowed more highly aligned, dense structures to be grown. By using low solution concentrations (5.0 × 10-4 M ZnCl 2) and non-electropolished Zn substrates, well faceted, hexagonal nano-rod structures of dimension ~80 nm diameter and >1 µm length were obtained. X-ray studies showed the samples to be highly aligned but containing a Zn-oxychloride impurity phase. Annealing caused the impurity phase to disappear and resulted in the films having a sharp photoluminescence double peak at 380/396 nm.

  19. A potentiometric biosensor for the detection of notch 3 using functionalized ZnO nanorods.

    PubMed

    Ibupoto, Z H; Khun, K; Liu, X; Willander, M

    2014-09-01

    The notch signalling plays a vital and radical role for the activity of cellular proliferation, differentiation and apoptosis. In this study, for the first time a particular biosensor is developed for the detection of notch 3. ZnO nanorods were fabricated on the gold coated glass substrate by hydrothermal method and afterwards were decorated with the gold nanoparticles by electrodepositing technique. Scanning electron microscopy (SEM) has shown the perpendicular to the substrate growth pattern of ZnO nanorods. X-ray diffraction (XRD) studies showed the c-axis oriented growth direction with wurtzite crystal structure of ZnO nanorods. X-ray Photoelectron Spectroscopy (XPS) and energy dispersive X-ray (EDX) techniques have shown the presence of Zn, O and Au atoms in the prepared functional material. Furthermore, the anti-notch 3 was physically adsorbed on the gold nanoparticles functionalized ZnO nanorods. The developed potentiometric immunosensor has shown response to the wide range of notch 3 molecules. The detected range included 1.00 x 10(-5)-1.50 x 10(0 ) μg/mL with a sensitivity of 23.15 ± 0.31 mV/decade. The analytical parameters including reproducibility, stability, and selectivity were also investigated and the observed results indicate the acceptable performance of the notch 3 biosensor. Moreover, the proposed notch 3 biosensor exhibited a fast response time of 10 s. PMID:25924320

  20. Photoelectrochemical performance of CdS nanorods grafted vertically aligned TiO{sub 2} nanorods

    SciTech Connect

    Liu, Ya; Jiang, Jiangang; Xu, Quan; Li, Mingtao; Guo, Liejin

    2013-11-15

    Graphical abstract: - Highlights: • TiO{sub 2} nanorods/CdS nanorods composite samples were successfully achieved. • The photocurrent density increased by 100 percent compared with pure TiO{sub 2}. • Photocurrent density increase mechanism of this photoanode was also forecasted. - Abstract: In this study, TiO{sub 2} nanorods/CdS nanorods composite samples were successfully synthesized by grafting CdS nanorods on vertically aligned TiO{sub 2} nanorods. A two-step hydrothermal method was used to prepare the samples. Some properties of the samples, such as morphological, structural, and optical properties were characterized by energy-dispersive X-ray detection, field emission scanning electron microscopy, X-ray diffraction, Raman spectroscopy, and ultraviolet-visible spectroscopy. Moreover, photoelectrochemical properties were studied via current-voltage and photocurrent spectrum measurements. The results showed that CdS nanorods grafted on top of TiO{sub 2} nanorods like a lawn. The amount grafted as well as the diameter and crystallinity of CdS nanorods increased first and then decreased as the grafting time increased, due to Ostwald ripening. Under the back-side illumination, the composite film with 2 h grafting time exhibited the highest photocurrent density which was almost twice of that of the pure TiO{sub 2} nanorods.

  1. Chloride ion addition for controlling shapes and properties of silver nanorods capped by polyvinyl alcohol synthesized by polyol method

    NASA Astrophysics Data System (ADS)

    Junaidi, Triyana, Kuwat; Harsojo, Suharyadi, Edi

    2016-04-01

    We report our investigation on the effect of chloride ions oncontrolling the shapes and properties of silver nanorods(AgNRs) synthesized using a polyol method. In this study, we used polyvinyl alcohol (PVA) as a capping agent and sodium chloride (NaCl) as asalt precursor and performed at the oilbath temperature of 140 °C. The chloride ions originating from the NaCl serve to control the growth of the silver nanorods. Furthermore, the synthesized silver nanorodswere characterized using UV-VIS, XRD, SEM and TEM. The results showed that besides being able to control the growth of AgCl atoms, the chloride ions were also able to control the growth of multi-twinned-particles into the single crystalline silver nanorods by micrometer-length. At an appropriate concentration of NaCl, the diameter of silver nanorodsdecreased significantly compared to that of without chloride ion addition. This technique may be useful since a particular diameter of silver nanorods affects a particular application in the future.

  2. Photoluminescence of spray pyrolysis deposited ZnO nanorods

    PubMed Central

    2011-01-01

    Photoluminescence of highly structured ZnO layers comprising well-shaped hexagonal rods is presented. The ZnO rods (length 500-1,000 nm, diameter 100-300 nm) were grown in air onto a preheated soda-lime glass (SGL) or ITO/SGL substrate by low-cost chemical spray pyrolysis method using zinc chloride precursor solutions and growth temperatures in the range of 450-550°C. We report the effect of the variation in deposition parameters (substrate type, growth temperature, spray rate, solvent type) on the photoluminescence properties of the spray-deposited ZnO nanorods. A dominant near band edge (NBE) emission is observed at 300 K and at 10 K. High-resolution photoluminescence measurements at 10 K reveal fine structure of the NBE band with the dominant peaks related to the bound exciton transitions. It is found that all studied technological parameters affect the excitonic photoluminescence in ZnO nanorods. PACS: 78.55.Et, 81.15.Rs, 61.46.Km PMID:21711895

  3. Structural and Morphology of ZnO Nanorods Synthesized Using ZnO Seeded Growth Hydrothermal Method and Its Properties as UV Sensing

    PubMed Central

    Ridhuan, Nur Syafinaz; Abdul Razak, Khairunisak; Lockman, Zainovia; Abdul Aziz, Azlan

    2012-01-01

    In this study, zinc oxide (ZnO) nanorod arrays were synthesized using a simple hydrothermal reaction on ZnO seeds/n-silicon substrate. Several parameters were studied, including the heat-treatment temperature to produce ZnO seeds, zinc nitrate concentration, pH of hydrothermal reaction solution, and hydrothermal reaction time. The optimum heat-treatment temperature to produce uniform nanosized ZnO seeds was 400°C. The nanorod dimensions depended on the hydrothermal reaction parameters. The optimum hydrothermal reaction parameters to produce blunt tip-like nanorods (770 nm long and 80 nm in top diameter) were 0.1 M zinc nitrate, pH 7, and 4 h of growth duration. Phase analysis studies showed that all ZnO nanorods exhibited a strong (002) peak. Thus, the ZnO nanorods grew in a c-axis preferred orientation. A strong ultraviolet (UV) emission peak was observed for ZnO nanorods grown under optimized parameters with a low, deep-level emission peak, which indicated high optical property and crystallinity of the nanorods. The produced ZnO nanorods were also tested for their UV-sensing properties. All samples responded to UV light but with different sensing characteristics. Such different responses could be attributed to the high surface-to-volume ratio of the nanorods that correlated with the final ZnO nanorods morphology formed at different synthesis parameters. The sample grown using optimum synthesis parameters showed the highest responsivity of 0.024 A/W for UV light at 375 nm under a 3 V bias. PMID:23189199

  4. Study of the structural and luminescent properties of ZnO nanorod arrays with hydrogen peroxide treatment

    NASA Astrophysics Data System (ADS)

    Su, Wen-Yan; Lin, Ching-Fuh

    2008-08-01

    One-dimensional nanostructures, such as nanowires, nanoneedles, nanobelts and nanotubes, have been extensively studied in recent years. These fascinating structures have the excellent physical properties owing to their geometry with high aspect ratio and modify the light-matter interaction. However, the defects of these structures are the obstacles for the practical applications. We report the influence of the hydrogen peroxide (H2O2) treatment on the point defects and structural defects of ZnO nanorods grown on n-type silicon. The ZnO nanorod arrays are prepared by low-cost hydrothermal method and the H2O2 treatments are investigated in two different approaches. One is to immerse ZnO nanorod samples into H2O2 solution. The other is a pre-treatment of spin-coating H2O2 solution on the seed layer before the growth of the ZnO nanorods. In the first approach, we found that the ultraviolet (UV) emission peak of the ZnO nanorods photoluminescence (PL) spectra was strongly dependent on the immersion time. In the second approach, the H2O2 solution not only influences the quality of the seed layer, but also the amount of the oxygen interstitial defects in the ZnO nanorods grown thereon. As a result, the UV emission intensity from the ZnO nanorods is enhanced almost five times. These effects are attributed to oxygen desorption through oxidation-reduction reactions of hydrogen peroxide on the ZnO surface. The ZnO nanorod arrays with few oxygen interstitial defects are prepared by low-cost and low-temperature hydrogen peroxide treatments, which are compatible with glass and polymer substrates and expected to enable the fabrication of optoelectronic device with excellent performance.

  5. Spin coating of Ag nanoparticles: Effect of reduction

    SciTech Connect

    Ansari, A. A. Sartale, S. D.

    2014-04-24

    A surfactant free method for the growth of Ag nanoparticles on glass substrate by spin coating of Ag ions solution followed by chemical reduction in aqueous hydrazine hydrate (HyH) solution has been presented. Appearance of surface plasmon resonance confirms the formation of Ag nanoparticles. Morphology and absorbance spectra of Ag nanoparticles films are used to examine effect of hydrazine concentration on the growth of Ag nanoparticles. SEM images show uniformly distributed Ag nanoparticles. Rate constant was found to be dependent on HyH concentration as a consequence influence particle size.

  6. Selective growth of ZnO nanorods on hydrophobic Si nanorod arrays

    NASA Astrophysics Data System (ADS)

    Lu, Ming-Yen; Wang, Ying-Jhe; Hong, Meng-Hsiang; Chiu, Cheng-Yao; You, Shuen-Jium; Lu, Ming-Pei

    2015-02-01

    In this paper we describe the selective growth of ZnO nanorods (NRs) on top of hydrophobic Si NR arrays. The periodic Si NR arrays, prepared through electroless chemical etching and HF treatment, functioned as hydrophobic substrates. Droplets containing ZnO seeds could be positioned on the Si NR arrays, causing the ZnO seeds to deposit selectively upon them, with n-ZnO NR/p-Si NR array heterojunctions ultimately forming after hydrothermal growth of ZnO NRs. Because of compensation for the difference in refractive index between air and the Si substrate, the n-ZnO NR/p-Si NR arrays exhibited excellent absorption ability in the visible range. Devices based on these n-ZnO NR/p-Si NR array heterojunctions displayed not only rectifying behavior but also photovoltaic effects when illuminated with UV light. The low temperature and low cost of this fabrication process suggest that the selective growth of n-ZnO NRs on p-Si NR arrays might allow such structures to have diverse applications in optoelectronics.

  7. Selective growth of ZnO nanorods on hydrophobic Si nanorod arrays.

    PubMed

    Lu, Ming-Yen; Wang, Ying-Jhe; Hong, Meng-Hsiang; Chiu, Cheng-Yao; You, Shuen-Jium; Lu, Ming-Pei

    2015-02-01

    In this paper we describe the selective growth of ZnO nanorods (NRs) on top of hydrophobic Si NR arrays. The periodic Si NR arrays, prepared through electroless chemical etching and HF treatment, functioned as hydrophobic substrates. Droplets containing ZnO seeds could be positioned on the Si NR arrays, causing the ZnO seeds to deposit selectively upon them, with n-ZnO NR/p-Si NR array heterojunctions ultimately forming after hydrothermal growth of ZnO NRs. Because of compensation for the difference in refractive index between air and the Si substrate, the n-ZnO NR/p-Si NR arrays exhibited excellent absorption ability in the visible range. Devices based on these n-ZnO NR/p-Si NR array heterojunctions displayed not only rectifying behavior but also photovoltaic effects when illuminated with UV light. The low temperature and low cost of this fabrication process suggest that the selective growth of n-ZnO NRs on p-Si NR arrays might allow such structures to have diverse applications in optoelectronics. PMID:25590263

  8. Texture evolution of vertically aligned biaxial tungsten nanorods using RHEED surface pole figure technique

    NASA Astrophysics Data System (ADS)

    Krishnan, R.; Liu, Y.; Gaire, C.; Chen, L.; Wang, G.-C.; Lu, T.-M.

    2010-08-01

    Vertically aligned biaxial tungsten nanorods with cubic A15 crystal structure were deposited by DC magnetron sputtering on native oxide covered Si(100) substrates with glancing angle flux incidence (θ ~ 85°) and a two-step substrate rotation mode at room temperature. These vertical nanorods were grown to different thicknesses (10, 25, 50 and 100 nm) and analyzed for biaxial texture evolution using a highly surface sensitive reflection high-energy electron diffraction (RHEED) pole figure technique. The initial polycrystalline film begins to show the inception of biaxial texture with a fiber background between 10 and 25 nm. Biaxial texture development is eventually completed between 50 and 100 nm thicknesses of the film. The out-of-plane crystallographic direction is [002] and the in-plane texture is selected so as to obtain maximum capture area. In a comparison with 100 nm thick inclined tungsten nanorods deposited at 85° without substrate rotation, it is found that the selection of in-plane texture does not maintain maximum in-plane capture area. This anomalous behavior is observed when the [002] texture axis is tilted ~ 17° from the substrate normal in the direction towards the glancing incident flux.

  9. Texture evolution of vertically aligned biaxial tungsten nanorods using RHEED surface pole figure technique.

    PubMed

    Krishnan, R; Liu, Y; Gaire, C; Chen, L; Wang, G-C; Lu, T-M

    2010-08-13

    Vertically aligned biaxial tungsten nanorods with cubic A15 crystal structure were deposited by DC magnetron sputtering on native oxide covered Si(100) substrates with glancing angle flux incidence (theta approximately 85 degrees) and a two-step substrate rotation mode at room temperature. These vertical nanorods were grown to different thicknesses (10, 25, 50 and 100 nm) and analyzed for biaxial texture evolution using a highly surface sensitive reflection high-energy electron diffraction (RHEED) pole figure technique. The initial polycrystalline film begins to show the inception of biaxial texture with a fiber background between 10 and 25 nm. Biaxial texture development is eventually completed between 50 and 100 nm thicknesses of the film. The out-of-plane crystallographic direction is [002] and the in-plane texture is selected so as to obtain maximum capture area. In a comparison with 100 nm thick inclined tungsten nanorods deposited at 85 degrees without substrate rotation, it is found that the selection of in-plane texture does not maintain maximum in-plane capture area. This anomalous behavior is observed when the [002] texture axis is tilted approximately 17 degrees from the substrate normal in the direction towards the glancing incident flux. PMID:20639581

  10. Nonionic fluorosurfactant as an ideal candidate for one-step modification of gold nanorods

    NASA Astrophysics Data System (ADS)

    Chen, Shuang; Yang, Ming; Hong, Song; Lu, Chao

    2014-02-01

    . Electronic supplementary information (ESI) available: Time dependence of the LSPR peak position after the gold nanorods were centrifuged at an etching time for 6 h; XRD patterns of the GNRs@CTAB and the GNRs@FSN deposited on a glass substrate, HRTEM images of the GNRs@CTAB and GNRs@FSN; UV-vis absorption spectra of the GNRs@CTAB after they were treated with 0.2% Brij-35, 0.2% Triton X-100 and 0.2% FSO for different time; UV-vis absorption spectra of GNRs@CTAB after they were centrifugated for three times, the centrifugal GNRs@CTAB with 0.2% FSN for 6 h and the centrifugal GNRs@CTAB with 0.2% FSN and 0.1 mM HAuCl4 for 6 h; UV-vis absorption spectra of the GNRs@FSN colloidal solution and after seven purification steps by high-speed centrifugation and re-dispersion into pure water; UV-vis absorption spectra of the GNRs@CTAB, the GNRs@FSN, and the GNRs@PEG at different PBS concentrations; influence of the pH values on the maximum absorbance of the GNRs@FSN, intensity-averaged size distribution plots of the GNRs@FSN at different pH values. See DOI: 10.1039/c3nr05546a

  11. Raman scattering enhanced within the plasmonic gap between an isolated Ag triangular nanoplate and Ag film.

    PubMed

    Li, Kuanguo; Jiang, Kang; Zhang, Lan; Wang, Yong; Mao, Lei; Zeng, Jie; Lu, Yonghua; Wang, Pei

    2016-04-22

    Enhanced electromagnetic field in the tiny gaps between metallic nanostructures holds great promise in optical applications. Herein, we report novel out-of-plane nanogaps composed of micrometer-sized Ag triangular nanoplates (AgTN) on Ag films. Notably, the new coupled plasmonic structure can dramatically enhance the surface-enhanced Raman scattering (SERS) by visible laser excitation, although the micrometer-sized AgTN has localized plasmon resonance at infrared wavelength. This enhancement is derived from the gap plasmon polariton between the AgTN and Ag film, which is excited via the antenna effect of the corner and edge of the AgTN. Systematic SERS studies indicated that the plasmon enhancement was on the order of corner > edge > face. These results were further verified by theoretical simulations. Our device paves the way for rational design of sensitive SERS substrates by judiciously choosing appropriate nanoparticles and optimizing the gap distance. PMID:26939539

  12. Raman scattering enhanced within the plasmonic gap between an isolated Ag triangular nanoplate and Ag film

    NASA Astrophysics Data System (ADS)

    Li, Kuanguo; Jiang, Kang; Zhang, Lan; Wang, Yong; Mao, Lei; Zeng, Jie; Lu, Yonghua; Wang, Pei

    2016-04-01

    Enhanced electromagnetic field in the tiny gaps between metallic nanostructures holds great promise in optical applications. Herein, we report novel out-of-plane nanogaps composed of micrometer-sized Ag triangular nanoplates (AgTN) on Ag films. Notably, the new coupled plasmonic structure can dramatically enhance the surface-enhanced Raman scattering (SERS) by visible laser excitation, although the micrometer-sized AgTN has localized plasmon resonance at infrared wavelength. This enhancement is derived from the gap plasmon polariton between the AgTN and Ag film, which is excited via the antenna effect of the corner and edge of the AgTN. Systematic SERS studies indicated that the plasmon enhancement was on the order of corner > edge > face. These results were further verified by theoretical simulations. Our device paves the way for rational design of sensitive SERS substrates by judiciously choosing appropriate nanoparticles and optimizing the gap distance.

  13. Shape and surface chemistry effects on the cytotoxicity and cellular uptake of metallic nanorods and nanospheres.

    PubMed

    Favi, Pelagie Marlene; Valencia, Mariana Morales; Elliott, Paul Robert; Restrepo, Alejandro; Gao, Ming; Huang, Hanchen; Pavon, Juan Jose; Webster, Thomas Jay

    2015-12-01

    Metallic nanoparticles (such as gold and silver) have been intensely studied for wound healing applications due to their ability to be easily functionalized, possess antibacterial properties, and their strong potential for targeted drug release. In this study, rod-shaped silver nanorods (AgNRs) and gold nanorods (AuNRs) were fabricated by electron beam physical vapor deposition (EBPVD), and their cytotoxicity toward human skin fibroblasts were assessed and compared to sphere-shaped silver nanospheres (AgNSs) and gold nanospheres (AuNSs). Results showed that the 39.94 nm AgNSs showed the greatest toxicity with fibroblast cells followed by the 61.06 nm AuNSs, ∼556 nm × 47 nm (11.8:1 aspect ratio) AgNRs, and the ∼534 nm × 65 nm (8.2:1 aspect ratio) AuNRs demonstrated the least amount of toxicity. The calculated IC50 (50% inhibitory concentration) value for the AgNRs exposed to fibroblasts was greater after 4 days of exposure (387.3 μg mL(-1)) compared to the AgNSs and AuNSs (4.3 and 23.4 μg mL(-1), respectively), indicating that these spherical metallic nanoparticles displayed a greater toxicity to fibroblast cells. The IC50 value could not be measured for the AuNRs due to an incomplete dose response curve. The reduced cell toxicity with the presently developed rod-shaped nanoparticles suggests that they may be promising materials for use in numerous biomedical applications. PMID:26053238

  14. Synthesis of novel AuPd nanoparticles decorated one-dimensional ZnO nanorod arrays with enhanced photoelectrochemical water splitting activity.

    PubMed

    Lu, Yan; Zhang, Junlong; Ge, Lei; Han, Changcun; Qiu, Ping; Fang, Siman

    2016-12-01

    The vertically aligned one-dimensional (1D) ZnO nanorod arrays decorated with AuPd alloy nanoparticles have been synthesized with ZnO nanorod arrays as template via a mild hydrothermal method. In this work, the as-prepared AuPd/ZnO nanorod arrays demonstrated high light-harvesting efficiency. The microstructures, morphologies and chemical properties of the obtained AuPd/ZnO composite photocatalyst were investigated by scanning electron microscopy (SEM), X-ray diffraction (XRD), transmission electron microscopy (TEM), UV-vis diffuse reflectance spectra (DRS) and X-ray photoelectron spectroscopy (XPS). The photoelectrochemical (PEC) performances of as-obtained AuPd/ZnO nanorod arrays were examined, and the photocurrent density was up to 0.98mAcm(-2) at 0.787V versus Ag/AgCl, which was about 2.4 times higher than the pure ZnO sample. A possible photocatalytic mechanism of the AuPd/ZnO hybrid nanostructures under the simulated sunlight irradiation was proposed to guide further improvement of other desirable materials. According to the above experiment results, it can be clearly found that AuPd/ZnO composite nanorod arrays showed excellent PEC performance and had promising applications in the utilization of solar energy. PMID:27552423

  15. Plasmonics of Gold Nanorods. Considerations for Biosensing

    NASA Astrophysics Data System (ADS)

    Liz-Marzán, Luis M.; Pérez-Juste, Jorge; Pastoriza-Santos, Isabel

    In this chapter, we explore the sensitivity of gold nanorods toward changes in the dielectric constant of the surrounding medium. Experimental data for pure and silica-coated nanorods with varying shell thickness are compared to calculations based on the boundary element method (BEM). They indicate that anisotropy and sharp tips make nanoparticles more environmentally sensitive. We also find that sensitivity decreases as silica shell thickness increases, as expected from a dielectric screening effect. Even when coated with thin shells, gold nanorods are found to be excellent candidates for biosensing applications.

  16. The stabilization and targeting of surfactant-synthesized gold nanorods

    NASA Astrophysics Data System (ADS)

    Rostro-Kohanloo, Betty C.; Bickford, Lissett R.; Payne, Courtney M.; Day, Emily S.; Anderson, Lindsey J. E.; Zhong, Meng; Lee, Seunghyun; Mayer, Kathryn M.; Zal, Tomasz; Adam, Liana; Dinney, Colin P. N.; Drezek, Rebekah A.; West, Jennifer L.; Hafner, Jason H.

    2009-10-01

    The strong cetyltrimethylammonium bromide (CTAB) surfactant responsible for the synthesis and stability of gold nanorod solutions complicates their biomedical applications. The critical parameter to maintain nanorod stability is the ratio of CTAB to nanorod concentration. The ratio is approximately 740 000 as determined by chloroform extraction of the CTAB from a nanorod solution. A comparison of nanorod stabilization by thiol-terminal PEG and by anionic polymers reveals that PEGylation results in higher yields and less aggregation upon removal of CTAB. A heterobifunctional PEG yields nanorods with exposed carboxyl groups for covalent conjugation to antibodies with the zero-length carbodiimide linker EDC. This conjugation strategy leads to approximately two functional antibodies per nanorod according to fluorimetry and ELISA assays. The nanorods specifically targeted cells in vitro and were visible with both two-photon and confocal reflectance microscopies. This covalent strategy should be generally applicable to other biomedical applications of gold nanorods as well as other gold nanoparticles synthesized with CTAB.

  17. Role of ZnO thin film in the vertically aligned growth of ZnO nanorods by chemical bath deposition

    NASA Astrophysics Data System (ADS)

    Son, Nguyen Thanh; Noh, Jin-Seo; Park, Sungho

    2016-08-01

    The effect of ZnO thin film on the growth of ZnO nanorods was investigated. ZnO thin films were sputter-deposited on Si substrate with varying the thickness. ZnO nanorods were grown on the thin film using a chemical bath deposition (CBD) method at 90 °C. The ZnO thin films showed granular structure and vertical roughness on the surface, which facilitated the vertical growth of ZnO nanorods. The average grain size and the surface roughness of ZnO film increased with an increase in film thickness, and this led to the increase in both the average diameter and the average length of vertically grown ZnO nanorods. In particular, it was found that the average diameter of ZnO nanorods was very close to the average grain size of ZnO thin film, confirming the role of ZnO film as a seed layer for the vertical growth of ZnO nanorods. The CBD growth on ZnO seed layers may provide a facile route to engineering vertically aligned ZnO nanorod arrays.

  18. The spontaneous formation and plasmonic properties of ultrathin gold-silver nanorods and nanowires stabilized in oleic acid.

    PubMed

    Crespo, Julian; López-de-Luzuriaga, José M; Monge, Miguel; Olmos, M Elena; Rodríguez-Castillo, María; Cormary, Benoît; Soulantica, Katerina; Sestu, Matteo; Falqui, Andrea

    2015-12-01

    Ultrathin Au-Ag alloy nanorods and nanowires of different lengths and ca. 1.9 nm diameter are prepared through a low-temperature decomposition of the precursor [Au2Ag2(C6F5)4(OEt2)2]n in oleic acid. This nanostructure formation has been studied through TEM, HRTEM, EDS, HS-SPME-GC-MS and (19)F NMR spectroscopy. The UNRs and UNWs display a length-dependent broad band in the mid-IR region that is related to the longitudinal mode of the surface plasmon resonance of the ultrathin nanostructures. PMID:26430906

  19. Picomolar detection of mercuric ions by means of gold-silver core-shell nanorods

    NASA Astrophysics Data System (ADS)

    Chen, Shouhui; Liu, Dingbin; Wang, Zhihua; Sun, Xiaolian; Cui, Daxiang; Chen, Xiaoyuan

    2013-07-01

    We report an ultrasensitive and selective probe for detection of mercuric ions using gold-silver core-shell nanorods as the substrate of surface-enhanced Raman scattering. The detection limit of this probe for mercuric ions can be as low as 1 pM. The efficiency of this probe in complex samples was evaluated by allowing detection of spiked mercuric ions in river water and fish samples.We report an ultrasensitive and selective probe for detection of mercuric ions using gold-silver core-shell nanorods as the substrate of surface-enhanced Raman scattering. The detection limit of this probe for mercuric ions can be as low as 1 pM. The efficiency of this probe in complex samples was evaluated by allowing detection of spiked mercuric ions in river water and fish samples. Electronic supplementary information (ESI) available: See DOI: 10.1039/c3nr01603j

  20. Optical forces in nanorod metamaterial

    PubMed Central

    Bogdanov, Andrey A.; Shalin, Alexander S.; Ginzburg, Pavel

    2015-01-01

    Optomechanical manipulation of micro and nano-scale objects with laser beams finds use in a large span of multidisciplinary applications. Auxiliary nanostructuring could substantially improve performances of classical optical tweezers by means of spatial localization of objects and intensity required for trapping. Here we investigate a three-dimensional nanorod metamaterial platform, serving as an auxiliary tool for the optical manipulation, able to support and control near-field interactions and generate both steep and flat optical potential profiles. It was shown that the ‘topological transition’ from the elliptic to hyperbolic dispersion regime of the metamaterial, usually having a significant impact on various light-matter interaction processes, does not strongly affect the distribution of optical forces in the metamaterial. This effect is explained by the predominant near-fields contributions of the nanostructure to optomechanical interactions. Semi-analytical model, approximating the finite size nanoparticle by a point dipole and neglecting the mutual re-scattering between the particle and nanorod array, was found to be in a good agreement with full-wave numerical simulation. In-plane (perpendicular to the rods) trapping regime, saddle equilibrium points and optical puling forces (directed along the rods towards the light source), acting on a particle situated inside or at the nearby the metamaterial, were found. PMID:26514667