scholarly journals Synthesis of Fe-Doped ZnO Nanorods by Rapid Mixing Hydrothermal Method and Its Application for High Performance UV Photodetector

2014 ◽  
Vol 2014 ◽  
pp. 1-9 ◽  
Author(s):  
Chan Oeurn Chey ◽  
Ansar Masood ◽  
A. Riazanova ◽  
Xianjie Liu ◽  
K. V. Rao ◽  
...  
Keyword(s):  
Photoelectron Spectroscopy ◽  
High Performance ◽  
Zno Nanorods ◽  
Hexagonal Wurtzite Structure ◽  
Secondary Phases ◽  
Simple Method ◽  
Uv Photodetector ◽  
X Ray ◽  
Doped Zno ◽  
Schottky Devices

We have successfully synthesized Fe-doped ZnO nanorods by a new and simple method in which the adopted approach is by using ammonia as a continuous source ofOH-for hydrolysis instead of hexamethylenetetramine (HMT). The energy dispersive X-ray (EDX) spectra revealed that the Fe peaks were presented in the grown Fe-doped ZnO nanorods samples and the X-ray photoelectron spectroscopy (XPS) results suggested that Fe3+is incorporated into the ZnO lattice. Structural characterization indicated that the Fe-doped ZnO nanorods grow along thec-axis with a hexagonal wurtzite structure and have single crystalline nature without any secondary phases or clusters of FeO or Fe3O4observed in the samples. The Fe-doped ZnO nanorods showed room temperature (300 K) ferromagnetic magnetization versus field (M-H) hysteresis and the magnetization increases from 2.5 μemu to 9.1 μemu for Zn0.99Fe0.01O and Zn0.95Fe0.05O, respectively. Moreover, the fabricated Au/Fe-doped ZnO Schottky diode based UV photodetector achieved 2.33 A/W of responsivity and 5 s of time response. Compared to other Au/ZnO nanorods Schottky devices, the presented responsivity is an improvement by a factor of 3.9.

scholarly journals High-Performance Flexible Ultraviolet Photodetectors with Ni/Cu-Codoped ZnO Nanorods Grown on PET Substrates

Nanomaterials ◽  
2019 ◽  
Vol 9 (8) ◽  
pp. 1067 ◽  
Author(s):  
Hafiz Muhammad Salman Ajmal ◽  
Fasihullah Khan ◽  
Noor Ul Huda ◽  
Sunjung Lee ◽  
Kiyun Nam ◽  
...  
Keyword(s):  
Photoelectron Spectroscopy ◽  
High Performance ◽  
Electronic Device ◽  
Deep Level ◽  
Zno Nanorods ◽  
Ultra Violet ◽  
Device Fabrication ◽  
Electrode Structure ◽  
Large Area ◽  
X Ray

As a developing technology for flexible electronic device fabrication, ultra-violet (UV) photodetectors (PDs) based on a ZnO nanostructure are an effective approach for large-area integration of sensors on nonconventional substrates, such as plastic or paper. However, photoconductive ZnO nanorods grown on flexible substrates have slow responses or recovery as well as low spectral responsivity R because of the native defects and inferior crystallinity of hydrothermally grown ZnO nanorods at low temperatures. In this study, ZnO nanorod crystallites are doped with Cu or Ni/Cu when grown on polyethylene terephthalate (PET) substrates in an attempt to improve the performance of flexible PDs. The doping with Ni/Cu or Cu not only improves the crystalline quality but also significantly suppresses the density of deep-level emission defects in as-grown ZnO nanorods, as demonstrated by X-ray diffraction and photoluminescence. Furthermore, the X-ray photoelectron spectroscopy analysis shows that doping with the transition metals significantly increases the oxygen bonding with metal ions with enhanced O/Zn stoichiometry in as-grown nanorods. The fabricated flexible PD devices based on an interdigitated electrode structure demonstrates a very high R of ~123 A/W, a high on-off current ratio of ~130, and a significant improvement in transient response speed exhibiting rise and fall time of ~8 and ~3 s, respectively, by using the ZnO nanorods codoped by Ni/Cu.

Simplified Synthesis of 3D Flexible Reduced Graphene Oxide-Wrapped NiCo2O4 Nanowires for High-Performance Supercapacitor

2018 ◽  
Vol 10 (3) ◽  
pp. 358-364 ◽  
Author(s):  
Chao Pan ◽  
Hongyu Sun ◽  
Jingyi Gao ◽  
Yucai Hu ◽  
Jing Wang
Keyword(s):  
Graphene Oxide ◽  
Reduced Graphene Oxide ◽  
Current Density ◽  
Photoelectron Spectroscopy ◽  
High Performance ◽  
High Current Density ◽  
Three Dimensional ◽  
Simple Method ◽  
X Ray ◽  
Reduced Graphene

We introduced a simple method to construct novel three-dimensional (3D) flexible hierarchical nanocomposites by combining (1D) NiCo2O4 nanowires with 2D reduced graphene oxide (rGO) sheets. The hierarchical nanocomposite structure of rGO-wrapped NiCo2O4 (rGO-NiCo2O4) was confirmed by X-ray diffraction (XRD), Raman spectra, scanning electron microscopy (SEM), transmission electron microscope (TEM), and X-ray photoelectron spectroscopy (XPS). The results indicated that NiCo2O4 nanowires were successfully wrapped in rGO and the morphology of the rGO-NiCo2O4 showed a three-dimensional porous structure with NiCo2O4 being homogeneously distributed in the rGO. Given their apparent advantages, these two different nanostructures were evaluated as electrodes for high-performance supercapacitors. These electrodes exhibited a high capacitance of 1824.8 F·g–1 at a current density of 0.5 A·g–1, and an excellent cycling performance extending to 5000 cycles at a high current density of 4 A·g–1. Our results clearly demonstrate that rGO sheets on NiCo2O4 nanowires can substantially improve the capacitive performance of materials and ultimately increase the cycling stability of supercapacitors. The hierarchical binary nanocomposites show excellent electrochemical properties for energy storage applications, evidencing their potential application as supercapacitors.

Thin Film growth and characterization of Ti doped ZnO by RF/DC magnetron sputtering

2015 ◽  
Vol 1731 ◽  
Author(s):  
M. Baseer Haider ◽  
Mohammad F. Al-Kuhaili ◽  
S. M. A. Durrani ◽  
Venkatesh Singaravelu ◽  
Iman Roqan
Keyword(s):  
Thin Film ◽  
Magnetron Sputtering ◽  
Photoelectron Spectroscopy ◽  
Film Growth ◽  
Chemical Study ◽  
Secondary Phases ◽  
Dc Magnetron Sputtering ◽  
X Ray ◽  
Force Microscopy ◽  
Doped Zno

ABSTRACTThin film Ti doped ZnO (Ti-ZnO) film were grown on sapphire (0001) substrate by RF and DC magnetron sputtering. Films were grown at a substrate temperature of 250 °C with different Ti/Zn concentration. Surface chemical study of the samples was performed by X-ray photoelectron spectroscopy to determine the stoichiometry and Ti/Zn ratio for all samples. Surface morphology of the samples were studied by atomic force microscopy. X-ray diffraction was carried out to determine the crystallinity of the film. No secondary phases of TixOy was observed. We observed a slight increase in the lattice constant with the increase in Ti concentration in ZnO. No ferromagnetic signal was observed for any of the samples. However, some samples showed super-paramagnetic phase.

scholarly journals Performance Improvement of UV Photodetectors using Cd-doped ZnO Nanostructures

2021 ◽  
Author(s):  
Fatemeh Abbasi ◽  
Fahimeh Zahedi ◽  
Mohammad hasan Yousefi
Keyword(s):  
Morphological Characteristics ◽  
Hexagonal Wurtzite Structure ◽  
X Ray Diffraction ◽  
Uv Photodetector ◽  
Pure Zinc ◽  
Current Time ◽  
X Ray ◽  
Metal Semiconductor Metal ◽  
Current Voltage ◽  
Doped Zno

Abstract The present research performed thermal decomposition to synthesize pure zinc oxide (ZnO) and cadmium-doped ZnO (ZnO:Cd) nanorods with ZnO to Cd weight ratios of 93:7, 95:5 and 97:3. Field emission scanning electron microscopy (FESEM), X-ray diffraction (XRD) and photoluminescence (PL) spectroscopy were performed and current/voltage and current/time measured to determine the optical, structural and morphological characteristics of ZnO and ZnO:Cd. The XRD results suggested the hexagonal wurtzite structure of all the samples and the successful incorporation of Cd into the ZnO structures. This incorporation caused a spherical to rod-like change in the shape of the nanostructures. An intense and sharp peak was observed at 380 nm (3.26 eV) in the UV region of the PL spectra of all the samples. A UV photodetector fabricated on the basis of ZnO and ZnO:Cd nanorods with a metal-semiconductor-metal configuration showed the significant photocurrent and photosensitivity of the ZnO:Cd samples in the UV photodetection application. The sensitivity of the fabricated ZnO photodetectors with Cd percentages of 0, 3, 5 and 7% was respectively obtained as 110.62, 463.28, 762.40 and 920.30. The fastest photoresponse, with a rise and decay time of 2.5 and 4 s, respectively, was associated with the sample doped with 5% Cd.

Synthesis and Sensing Properties of N-doped ZnO Nanorod Arrays on Quartz

2010 ◽  
Vol 1253 ◽  
Author(s):  
Boqian Yang ◽  
Xiaoyan Peng ◽  
Hongxin Zhang ◽  
Peterxian Feng ◽  
Marc Achermann
Keyword(s):  
Photoelectron Spectroscopy ◽  
Zno Nanorods ◽  
Zno Nanorod ◽  
Nanorod Arrays ◽  
Zno Nanorod Arrays ◽  
X Ray ◽  
Doped Zno ◽  
High Concentrations ◽  
Diffraction Patterns ◽  
Raman Scattering Spectra

AbstractUsing different pressures of nitrogen, N-doped ZnO nanorod arrays of various densities have been synthesized on quartz substrates by pulsed laser deposition techniques. The nanorods grow preferentially perpendicular to the quartz surface. X-ray diffraction patterns revealed some degradation of the crystal structure at elevated nitrogen pressures. High concentrations of nitrogen doping in ZnO nanorods were estimated by X-ray photoelectron spectroscopy. Raman scattering spectra confirmed the wurtzite structure of N-doped ZnO nanorods. A prototype sensor based on the N-doped ZnO nanorod arrays demonstrates a linear dependence of the conductivity with operating temperature and pressure of a test gas pollutant.

STRUCTURAL, OPTICAL AND MAGNETIC INVESTIGATIONS ON UNDOPED AND Mn-DOPED ZnO NANOPARTICLES

2010 ◽  
Vol 09 (05) ◽  
pp. 495-502 ◽  
Author(s):  
N. RAJKUMAR ◽  
K. RAMACHANDRAN
Keyword(s):  
Zno Nanoparticles ◽  
Photoelectron Spectroscopy ◽  
Spherical Particles ◽  
Precipitation Method ◽  
Chemical Compositions ◽  
Secondary Phases ◽  
X Ray ◽  
Doped Zno ◽  
Co Precipitation ◽  
Mn Doped

Undoped and Mn (1 and 3 at.%) doped ZnO nanoparticles were synthesized by a simple chemical co-precipitation method. Rietveld refinement of X-ray diffraction (XRD) data revealed that undoped and Mn doped ZnO nanoparticles crystallize in the monophasic wurtzite structure and monotonous expansion of the lattice constants with increasing Mn content, due to the effective Mn doping. TEM images of all the samples showed the monodispersive spherical particles with the size of ~7 nm. The quantum confinement of nanoparticles was tested from UV–Vis absorbance measurement and the particle sizes were calculated and compared with TEM and XRD. The chemical compositions were analyzed by energy dispersive spectroscopy (EDS). In order to investigate the origin of ferromagnetism, the electronic structures of the Zn , O , and Mn atoms were probed by X-ray photoelectron spectroscopy (XPS). XPS data revealed that most of the dopants (Mn) exists in +2 oxidation state for 3 at.% Mn doped ZnO sample. The magnetization curves of the Mn doped ZnO samples indicate the existence of room-temperature ferromagnetic (RTFM) behavior. Here the observed RTFM in Mn doped ZnO can be attributed to the substitutional incorporation of Mn at Zn sites rather than due to the formation of any secondary phases.

scholarly journals A highly efficient porous rod-like Ce-doped ZnO photocatalyst for the degradation of dye contaminants in water

2019 ◽  
Vol 10 ◽  
pp. 1157-1165 ◽  
Author(s):  
Binjing Hu ◽  
Qiang Sun ◽  
Chengyi Zuo ◽  
Yunxin Pei ◽  
Siwei Yang ◽  
...  
Keyword(s):  
Photoelectron Spectroscopy ◽  
Large Scale ◽  
Degradation Rate ◽  
Ph Value ◽  
Influential Factor ◽  
Experimental Conditions ◽  
Simple Method ◽  
X Ray ◽  
Highly Efficient ◽  
Doped Zno

A mild and simple method was developed to synthesize a highly efficient photocatalyst comprised of Ce-doped ZnO rods and optimal synthesis conditions were determined by testing samples with different Ce/ZnO molar ratios calcined at 500 °C for 3 hours via a one-step pyrolysis method. The photocatalytic activity was assessed by the degradation of a common dye pollutant found in wastewater, rhodamine B (RhB), using a sunlight simulator. The results showed that ZnO doped with 3% Ce exhibits the highest RhB degradation rate. To understand the crystal structure, elemental state, surface morphology and chemical composition, the photocatalysts were characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), scanning electron microscope (SEM) and inductively coupled plasma emission spectroscopy (ICP), respectively. The newly developed, robust, field-only surface integral method was employed to explore the relationship between the remarkable catalytic effect and the catalyst shape and porous microstructure. The computational results showed that the dipole-like field covers the entire surface of the rod-like Ce-doped ZnO photocatalyst and is present over the entire range of wavelengths considered. The optimum degradation conditions were determined by orthogonal tests and range analysis, including the concentration of RhB and catalyst, pH value and temperature. The results indicate that the pH value is the main influential factor in the photocatalytic degradation process and the optimal experimental conditions to achieve the maximum degradation rate of 97.66% in 2 hours are as follows: concentration (RhB) = 10 mg/L, concentration (catalyst) = 0.7 g/L, pH 9.0 and T = 50 °C. These optimum conditions supply a helpful reference for large-scale wastewater degradation containing the common water contaminant RhB.

Hydrothermally Grown Copper-Doped ZnO Nanorods on Flexible Substrate

2019 ◽  
Vol 14 (11) ◽  
pp. 1503-1511 ◽  
Author(s):  
Hafiz Muhammad Salman Ajmal ◽  
Waqar Khan ◽  
Fasihullah Khan ◽  
Noor-ul Huda ◽  
Sam-Dong Kim
Keyword(s):  
Photoelectron Spectroscopy ◽  
Flexible Substrate ◽  
Sol Gel ◽  
Zno Nanorods ◽  
Atomic Ratio ◽  
Crystalline Quality ◽  
Near Band Edge ◽  
Band Edge Emission ◽  
X Ray ◽  
Doped Zno

In this study, we observe the effect of Cu doping on the ZnO nanorod (NR) structure grown on a polyethylene terephthalate flexible substrates by hydrothermal growth of sol–gel method proceeded at 150 °C. Copper (II) nitrate trihydrate (Cu-nitrate) and copper (II) acetate monohydrate (Cu-acetate) are employed as precursors for Cu dopants in aqueous growth solution to examine the evolutionary change of the growth morphology, optical characteristics, and chemical composition of as-grown ZnO NRs. A significant influence of dopant molarity on the morphology of wurtzite ZnO nanocrystals is observed by field-emission scanning electron microscopy. X-ray diffraction analysis also reveals more enhanced crystalline quality from Cu-doped NR crystals prepared by Cu-acetates than that grown with Cu-nitrate precursor. Near band-edge emission of 2 mM Cu-acetate doped NRs is greatly enhanced by 2.5 times compared to those grown with Cu-nitrate precursors. A great reduction in visible emissions is also realized, and this phenomenon is associated with overall improvement in NR crystalline quality by suppressing the oxygenated carbon groups or hydroxyl introduced by the aqueous solution-based growth. X-ray photoelectron spectroscopy also shows that a very high O/Zn atomic ratio of 0.73 can be achieved in the case of NR crystals prepared by 2 mM Cu-acetate. Cu doped ZnO nanostructures of improved optical and structural properties achieved in this study can be utilized in the wide emerging field of flexible device applications such as laser diodes, light-emitting diodes, piezoelectric transducers and generators, gas sensors, and ultraviolet detectors.

scholarly journals Novel Carbon Dots Derived from Glycyrrhizae Radix et Rhizoma and Their Anti-Gastric Ulcer Effect

Molecules ◽  
2021 ◽  
Vol 26 (6) ◽  
pp. 1512
Author(s):  
Yuhan Liu ◽  
Meiling Zhang ◽  
Jinjun Cheng ◽  
Yue Zhang ◽  
Hui Kong ◽  
...  
Keyword(s):  
Gastric Ulcer ◽  
Photoelectron Spectroscopy ◽  
Carbon Dots ◽  
High Performance ◽  
Raw264.7 Cells ◽  
Mice Model ◽  
X Ray ◽  
Glycyrrhizae Radix ◽  
Transmission Electron ◽  
High Resolution Tem

Glycyrrhizae Radix et Rhizoma (GRR) is one of the commonly used traditional Chinese medicines in clinical practice, which has been applied to treat digestive system diseases for hundreds of years. GRR is preferred for anti-gastric ulcer, however, the main active compounds are still unknown. In this study, GRR was used as precursor to synthesize carbon dots (CDs) by a environment-friendly one-step pyrolysis process. GRR-CDs were characterized by using transmission electron microscopy, high-resolution TEM, fourier transform infrared, ultraviolet-visible and fluorescence spectroscopy, X-ray photoelectron spectroscopy, X-ray diffraction and high-performance liquid chromatography. In addition, cellular toxicity of GRR-CDs was studied by using CCK-8 in RAW264.7 cells, and the anti-gastric ulcer activity was evaluated and confirmed using mice model of acute alcoholic gastric ulcer. The experiment confirmed that GRR-CDs were the spherical structure with a large number of active groups on the surface and their particle size ranged from 2 to 10 nm. GRR-CDs had no toxicity to RAW264.7 cells at concentration of 19.5 to 5000 μg/mL and could reduce the oxidative damage of gastric mucosa and tissues caused by alcohol, as demonstrated by restoring expression of malondialdehyde, superoxide dismutase and nitric oxide in serum and tissue of mice. The results indicated the explicit anti-ulcer activity of GRR-CDs, which provided a new insights for the research on effective material basis of GRR.

Preparation of Visible-Light-Responsive TiO2-xNx Photocatalyst by a Very Simple Method

2011 ◽  
Vol 383-390 ◽  
pp. 3188-3191
Author(s):  
Han Jie Huang ◽  
Wen Long She ◽  
Ling Wen Yang ◽  
Hai Peng Huang
Keyword(s):  
Photocatalytic Activity ◽  
Visible Light ◽  
Photoelectron Spectroscopy ◽  
Diffuse Reflection ◽  
Ammonia Solution ◽  
Reflection Spectra ◽  
X Ray Diffraction ◽  
Simple Method ◽  
X Ray ◽  
Light Excitation

A visible-light-responsive TiO2-xNx photocatalyst was prepared by a very simple method. Ammonia solution was used as nitrogen resource in this paper. The TiO2-xNx photocatalyst was characterized by X-ray diffraction (XRD), Brunauer-Emmett-Teller (BET), UV-Vis diffuse reflection spectra (DRS), and X-ray photoelectron spectroscopy (XPS). The ethylene was selected as a target pollutant under visible light excitation to evaluate the activity of this photocatalyst. The new prepared TiO2-xNx photocatalyst with strong photocatalytic activity under visible light irradiation was demonstrated in the experiment.

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