Synthesis of Ag Nanoparticle-Decorated ZnO Nanorods Adopting the Low-Temperature Hydrothermal Method (original) (raw)
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Lithuanian Journal of Physics
We examine the influence of colloidal Au and Ag nanoparticles (NP) on hydrothermally grown ZnO nanorods (NR). Individual 60 nm diameter NP and small NP assemblies without formation of large aggregates were deposited on poly-L-lysine covered NR films using the dip-coating method. The evaluation of morphological and optical properties of the obtained ZnO-metal hybrids was done using scanning electron microscopy, photoluminescence (PL) and diffuse reflection spectroscopy. The presence of Au NP selectively suppressed the PL components near 560 nm wavelength associated with ZnO surface defects, whereas equally sized Ag NP resulted in a much smaller change of PL signal, barely above the noise level. The presented results may be useful for tuning the optical properties of hybrid materials in development of sensor or photovoltaic devices.
Photoluminescence Emission and Structure Diversity in ZnO:Ag Nanorods
Journal of Physics: Conference Series, 2015
The photoluminescence, its temperature dependences, as well as structural characteristics by methods of Scanning electronic microscopy (SEM) have been studied in ZnO:Ag nanorods prepared by the ultrasonic spray pyrolysis (USP). The PL spectra of the ZnO:Ag NRs over the temperature range from 10 K to 300 K are investigated. Three types of PL bands have been revealed: i) the near-band-edge (NBE) emissions, ii) defect related emission and iii) IR emissions. It is shown the IR emission corresponds to the second-order diffraction of the near-band-edge (NBE) emission bands. The study of NBE PL temperature dependences reveals that the acceptor bound exciton (ABE) and its second-order diffraction peak disappeared at the temperature higher than 200 K. The attenuation of the ABE peak intensity is ascribed to the thermal dissociation of ABE with appearing of a free exciton (FE). The PL bands, related to the LO phonon replica of FE and its second-order diffraction, dominate in the PL spectra at room temperature that testify on the high quality of the ZnO:Ag films prepared by the USP technology.
Synthesized ZnO nanorod with different range of morphologies using a simple hydrothermal method
INTERNATIONAL CONFERENCE OF NUMERICAL ANALYSIS AND APPLIED MATHEMATICS ICNAAM 2019, 2020
Zinc oxide nanorods have been synthesized by a hydrothermal method using a two different synthesis condition at low temperature. First sample have been grown at 122 C° temperature for 4 hours in the autoclave then at room temperature for two days and the second sample have been synthesized at 122C° for 4 hours in autoclave only. All products have been checked by using UV-Visible absorption and photoluminescence (PL), and the morphology have been studied by (FE-SEM), and AFM. In this work have been synthesized the hexanol nanorods (HZNR) at 122C° temperature for 4 hours in autoclave, while the Zinc oxide nanorod (ZNR) have been growth at 122C° for 4 hours in autoclave then two days at room temperature. UV-visible spectra show increased at excitonic absorption peaks in visible region with HZNR more than ZNR. All samples were observed that had high absorption in UV regain of spectra. Energy gup (Eg) degreased at HZNR (3) eV compared with ZNR (3.2) eV. In PL spectra, the band visible emission peaks were observed for all synthesized products (HZNR &ZNR) at 430 and 480 nm and high intense band centers at 688 for ZNR and 670 for HZNR However, the PL intensity peaks were reduced at (670 nm) for (HZNR) sample. the morphology of the sample was different when the temperature was changed. a hydrothermal method is uncomplicated, simple, cheap and environmentally, which made it favorable for huge-scale preparation for design and other application.
Ag-doped ZnO nanorods synthesized by two-step method
Chinese Physics B, 2012
A two-step method is adopted to synthesize Ag-doped ZnO nanorods. A ZnO seed layer is first prepared on a glass substrate by thermal decomposition of zinc acetate. Ag-doped ZnO nanorods are then assembled on the ZnO seed layer using the hydrothermal method. The influences of the molar percentage of Ag ions to Zn ions (RAg/Zn) on the structural and optical properties of the ZnO nanorods obtained are carefully studied using X-ray diffractometry, scanning electron microscopy and spectrophotometry. Results indicate that Ag ions enter into the crystal lattice through the substitution of Zn ions. The (002) c-axis-preferred orientation of the ZnO nanorods decreases as RAg/Zn increases. At RAg/Zn > 1.0%, ZnO nanorods lose their c-axis-preferred orientation and generate Ag precipitates from the ZnO crystal lattice. The average transmissivity in the visible region first increases and then decreases as RAg/Zn increases. The absorption edge is first blue shifted and then red shifted. The inf...
Pure and silver added zinc oxide nanoparticles (ZnO-NPs and ZnO:Ag-NPs) were synthesized through a modified sol–gel method. The prepared samples were characterized using X-ray diffraction (XRD), transmission electron microscopy (TEM) and photoluminescence (PL) spectroscopy. In the XRD patterns, silver diffracted peaks were also observed for the samples synthesized at different calcination temperatures of 500◦C, 700◦C, 900◦C except 1100◦C, in addition to ZnO. TEM images indicated that the average size of ZnO:Ag-NPs increases with the amount of Ag concentration. The PL spectra of the samples revealed that the increase of Ag concentration results in the increase of the visible emission intensity, whereas by increasing the calcination temperature the intensity of visible emission of the samples decreases.
Journal of Luminescence, 2013
To investigate the effect of a seed layer on the growth and properties of ZnO nanorods using hydrothermal technique, various thickness of sputter deposited ZnO thin films were used. The changes in crystallinity, orientation, and optical properties of the nanorods synthesized on these ZnO thin films were examined. These properties were studied simultaneously in two series of samples, wherein in one series the nanorods were unannealed while in the other series they were annealed. Structural characterization revealed that both categories of nanorods were highly crystalline, with a hexagonal phase, and grew along the [0001] direction. The density of the nanorods per unit area increased as the thickness of the seed layer decreased. We also found that the defect related emission in photoluminescence spectra was quite low in both the annealed and non-annealed samples series. Typically, the decay curves obtained from these ZnO nanorods show a combination of two exponential decays. The nonradiative fast decay component was affected by the thickness of the seed layer and its values were higher than those of previously reported ZnO nanostructures grown by the hydrothermal technique. This comprehensive study shows that as grown nanorods lead directly to a high crystalline quality.
Substrate effect of hydrothermally grown ZnO nanorods and its luminescence properties
Journal of Experimental Nanoscience, 2012
We report the hexagonal wurtzite crystalline structure of ZnO nanorod growth by hydrothermal chemical wet synthesis at low temperature (90°C). We have used p-Si (100), n-Si (100), α-quartz (0001), MgO (0001) and ITO (polycrystalline) substrates to understand the growth mechanism of ZnO nanorods with a low pressure environment. X-ray diffraction study confirms the hexagonal structure of the ZnO nanorod. Scanning electron microscopy (SEM) also shows the hexagonal structure along with different size and width of the nanorods. The substrate effect of nanorods has been explained on the basis of adatom kinetics during the growth. We observed that the nanorods were grown from a single nucleation point with 4–5 different branches on the ITO substrate with uniform length and width, whereas MgO substrate shows curled flower architecture across the whole area. The photoluminescence illustrates strong substrate effect. A wide range of UV emission bands along with visible emission has been observed from the ZnO nanorods deposited on different substrates.
Photoluminescence of ZnO nanorods prepared by hydrothermal method
Journal of Physics: Conference Series, 2019
In this research, the effects of calcination temperature and reaction time on the photoluminescent properties of ZnO nanorods prepared by hydrothermal processes were studied. Morphology, crystalline structure and photoluminescent properties of the prepared samples were analyzed by scanning electron microscope (SEM), X-ray diffractrometer (XRD) and fluorescent spectrophotometer. The study found that a reaction time of 5 hours on a glass slide and calcination at 500°C was the best preparation condition. The prepared ZnO nanorods were aligned without direction and distributed throughout the substrate. The average diameter of the prepared ZnO nanorods was 91.96 ± 21.16 nm. The prepared ZnO nanorods comprised a hexagonal crystalline structure with an emission peak in the UV range.
2017
In this research ZnO nanorods with having clear hexagonal shapes from a lower precursor concentration (1 mM-9 mM) are produced. ZnO nanorods with different shape and sizes have been prepared on chromium/gold (Cr/Au) glass substrate through hydrothermal method. The effect of concentrations of equimolar solution on the synthesis of ZnO nanorods is investigated. The ZnO nanorods growth have been characterized by using field emission scanning electron microscope (FESEM), energy dispersive X-ray spectroscopy (EDX), and X-ray diffraction (XRD) to investigate the surface morphology, the elemental and the structure analysis, respectively. It is observed that the precursor concentration has a significant influence on the morphology and crystal structure, crystal size, and FWHM of ZnO nanorods. ZnO nanorods were grown in high density with an orientation along c-axis /of the substrate. It also exhibits hexagonal structure with a dominant (002) peak in XRD spectrum and possesses a high crystal quality. The effect of concentration on atomic percentage of constituent atoms is also studied. The atomic percentage ratio of Zn to O change from 32.5: 67.5 to 48: 52 as the precursor concentration increase 1-9 mM.
Journal of Crystal Growth, 2020
Coupling of selected metal nanoparticles (NPs) on the surface of ZnO nanorods (NRs) array grown on conductive glass substrates is one of the approaches to tailor the optical properties of ZnO NRs. It is a metal oxide deposition process followed by an annealing treatment to convert the deposits to metal NPs. However, the conductive glass substrates could easily deform during this annealing process. This issue limits the application of ZnO NRs array that grown on glass substrates for the fabrication of ZnO based devices. Thus, the development of metal NPs deposition technique without the need of post-deposition annealing is highly desired. This work demonstrated a successful and controlled deposition of silver (Ag) NPs on ZnO NRs array grown on fluorine doped tin oxide (FTO) glass substrates without any post-deposition annealing and, the product has exhibited localized surface plasmonic resonance (LSPR) phenomenon. The ZnO NRs arrays were grown on FTO glass substrates that preseeded with ZnO layer using hydrothermal method. The controlled coupling of Ag NPs particles on ZnO NRs was performed by adjusting the duration of photo-reduction process. The optical bandgap ZnO NRs was widened because of Ag NPs coupling, i.e. from 3.16 to 3.22 eV; as estimated from the result of UV-Vis measurement. The shift of near band-edge emission (NBE) in room temperature photoluminescence (RTPL) suggests that the presence of Ag NPs on the surface of ZnO NRs could block the transitions of electrons in ZnO whereas the shift in defect-related emission indicates the generation of defects at the interfaces between Ag NPs and ZnO NRs. The 5folds increment of I UV / Vis ratio of Ag NPs/ZnO NRs in RTPL, indicating the specimens experienced LSPR effect. The LSPR effect of Ag NPs/ZnO NRs could be used to improve the performance of ZnO-based devices such as solar cells, light-emitting diodes and photocatalysts applications.