ENHANCED GAS SENSING PROPERTIES OF p-TYPE TeO2 NANORODS FUNCTIONALIZED WITH Pd

NANO ◽  
2011 ◽  
Vol 06 (05) ◽  
pp. 455-460 ◽  
Author(s):  
HYUNSU KIM ◽  
SUNGHOON PARK ◽  
CHANGHYUN JIN ◽  
CHONGMU LEE
Keyword(s):  
Electron Microscopy ◽  
Gas Sensing ◽  
Average Diameter ◽  
Pd Nanoparticles ◽  
Face Centered Cubic ◽  
X Ray Diffraction ◽  
Sensing Properties ◽  
Transmission Electron ◽  
Face Centered ◽  
P Type

TeO2 nanorods functionalized with Pd were prepared by a three-step process comprising thermal evaporation of Te powders, Pd deposition by photo-reduction, and annealing. Sensors were fabricated by using the Pd -functionalized TeO2 nanorods. Scanning electron microscopy images exhibited that the nanorods with diameters in a range of 50–100 nm and lengths of a few micrometers were covered with the Pd nanoparticles with an average diameter of ~ 15 nm. Transmission electron microscopy and X-ray diffraction analysis revealed that the nanorods were monocrystalline simple tetragonal TeO2 . On the other hand, the nanoparticles on them were confirmed to be nanocrystalline face-centered cubic Pd . The multiple-networked TeO2 nanorod sensors exhibited a sensitivity of 3.13% at 100 ppm NO2 at 300°C, whereas the Pd -functionalized TeO2 nanorod sensors exhibited a sensitivity of 11.97% under the same condition. The recovery time of TeO2 nanorods was decreased considerably at every NO2 concentration by the Pd -functionalization even if the response time decreased or increased slightly depending upon the NO2 concentration. In addition, the origin of the enhancement of the sensing properties of the TeO2 nanorods by functionalization with Pd is discussed.

High photoelectric PPV/PVA/Ag composite nanofibers by co-electrospinning

2015 ◽  
Vol 35 (7) ◽  
pp. 689-697 ◽  
Author(s):  
Yang Gao ◽  
Zhiyao Sun ◽  
Liguo Sun ◽  
Cheng Wang ◽  
Shuhong Wang ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Composite Nanofibers ◽  
Average Diameter ◽  
Face Centered Cubic ◽  
X Ray Diffraction ◽  
Ag Nps ◽  
Photoelectric Properties ◽  
Transmission Electron ◽  
Face Centered ◽  
Xrd Patterns

Abstract Poly(phenylene vinylene)/polyvinyl alcohol/Ag (PPV/PVA/Ag) composite nanofibers with excellent photoelectric properties were prepared by coaxial electrospinning using PPV/PVA as the shell and Ag nanoparticles (NPs) as the core, Ag NPs aqueous solution was prepared by the reduction method. The results of scanning electron microscopy (SEM) and transmission electron microscopy (TEM) showed that Ag NPs are of a face-centered cubic structure, with an average diameter of 46 nm and the composite nanofibers have uniform and continuous morphology. With increasing Ag content, the diameters of the composite nanofibers decreased from 653 nm to 250 nm. The X-ray diffraction (XRD) patterns verified that in the composite nanofibers, the Ag NPs are not transformed. In the photoluminescence spectra, the PPV/PVA/Ag composite nanofibers presented red-shift compared with PPV/PVA nanofibers. Under illumination, the as-prepared PPV/PVA/Ag composite nanofibers exhibited relatively high photocurrent intensity.

Structural, morphological, and magnetic study of nanocrystalline cobalt-copper powders synthesized by the polyol process

1995 ◽  
Vol 10 (6) ◽  
pp. 1546-1554 ◽  
Author(s):  
G.M. Chow ◽  
L.K. Kurihara ◽  
K.M. Kemner ◽  
P.E. Schoen ◽  
W.T. Elam ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Face Centered Cubic ◽  
X Ray Diffraction ◽  
X Ray ◽  
Transmission Electron ◽  
Copper Powders ◽  
Face Centered ◽  
Increasing Temperature ◽  
X Ray Absorption

Nanocrystalline CoxCu100−x (4 ⋚ x ⋚ 49 at. %) powders were prepared by the reduction of metal acetates in a polyol. The structure of powders was characterized by x-ray diffraction (XRD), transmission electron microscopy (TEM), high resolution transmission electron microscopy (HRTEM), extended x-ray absorption fine structure (EXAFS) spectroscopy, solid-state nuclear magnetic resonance (NMR) spectroscopy, and vibrating sample magnetometry (VSM). As-synthesized powders were composites consisting of nanoscale crystallites of face-centered cubic (fcc) Cu and metastable face-centered cubic (fcc) Co. Complementary results of XRD, HRTEM, EXAFS, NMR, and VSM confirmed that there was no metastable alloying between Co and Cu. The NMR data also revealed that there was some hexagonal-closed-packed (hcp) Co in the samples. The powders were agglomerated, and consisted of aggregates of nanoscale crystallites of Co and Cu. Upon annealing, the powders with low Co contents showed an increase in both saturation magnetization and coercivity with increasing temperature. The results suggested that during preparation the nucleation of Cu occurred first, and the Cu crystallites served as nuclei for the formation of Co.

Sensing Properties of CNT hybrid MOS-based Sensors

2004 ◽  
Vol 828 ◽  
Author(s):  
Wei-Jen Liou ◽  
Tsung-Yeh Yang ◽  
Kuang-Nan Lin ◽  
Ching-Hong Yang ◽  
Hong-Ming Lin
Keyword(s):  
Electron Microscopy ◽  
Gas Adsorption ◽  
Gas Sensing ◽  
Sol Gel ◽  
Gas Sensitivity ◽  
Sensing Properties ◽  
Operation Temperature ◽  
Transmission Electron ◽  
Lower Temperature ◽  
P Type

ABSTRACTThe carbon nanotubes provide large surface that can enhance the gas adsorption properties and increase the conductivity at a lower temperature for gas sensing. The gas sensing properties of the hybrid TiO2/CNTs material are examined in this study. The sol-gel technique is used to prepare a thin layer of nano-TiO2 coated on CNTs. The structure of TiO2/CNTs hybrid materials is identified by X-ray diffraction (XRD) and Raman spectrum. The granules and surface morphology are analyzed by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The electrical properties of the hybrid TiO2/CNTs indicate that the operation temperature can be lowered to ambient temperature and this will enhance the gas sensitivity for detecting CO gas. The n-type or p-type behavior of hybrid TiO2/CNTs can be controlled by the coating thickness of hybrid TiO2. According to the image results, the mechanisms of the n-type and p-type behavior of hybrid TiO2/CNTs system are proposed.

scholarly journals Development of Ternary and Quaternary Catalysts for the Electrooxidation of Glycerol

2012 ◽  
Vol 2012 ◽  
pp. 1-6 ◽  
Author(s):  
L. M. Artem ◽  
D. M. Santos ◽  
A. R. De Andrade ◽  
K. B. Kokoh ◽  
J. Ribeiro
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Cyclic Voltammetry ◽  
Pechini Method ◽  
Particle Sizes ◽  
Face Centered Cubic ◽  
X Ray Diffraction ◽  
X Ray ◽  
Transmission Electron ◽  
Face Centered

This work consisted in the preparation of platinum-based catalysts supported on carbon (Vulcan XC-72) and investigation of their physicochemical and electrochemical properties. Catalysts of the C/Pt-Ni-Sn-Me (Me = Ru or Ir) type were prepared by the Pechini method at temperature of350∘C. Four different compositions were homemade: C/Pt60Sn10Ni30, C/Pt60Sn10Ni20Ru10, C/Pt60Sn10Ni10Ru20, and C/Pt60Sn10Ni10Ir20. These catalysts were electrochemically and physically characterized by cyclic voltammetry (CV), chronoamperometry (CA) in the presence of glycerol 1.0 mol dm-3, X-ray diffraction (XRD), and high-resolution transmission electron microscopy (HRTEM). XRD results showed the main peaks of face-centered cubic Pt. The particle sizes obtained from XRD and HRTEM experiments were close to values ranging from 3 to 8.5 nm. The CV results indicate behavior typical of Pt-based catalysts in acid medium. The CV and CA data reveal that quaternary catalysts present the highest current density for the electrooxidation of glycerol.

scholarly journals A Sequence of Phase Transformations and Phases in NiCoFeCrGa High Entropy Alloy

Materials ◽  
2021 ◽  
Vol 14 (5) ◽  
pp. 1076
Author(s):  
Ádám Vida ◽  
János Lábár ◽  
Zoltán Dankházi ◽  
Zsolt Maksa ◽  
Dávid Molnár ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Phase Transitions ◽  
High Entropy Alloy ◽  
Face Centered Cubic ◽  
X Ray Diffraction ◽  
High Entropy ◽  
Transmission Electron ◽  
Temperature Ranges ◽  
Face Centered ◽  
Electron Energy Loss

The present investigation is directed to phase transitions in the equimolar NiCoFeCrGa high entropy alloy, which is a mixture of face-centered cubic (FCC) and body-centered cubic (BCC) crystalline phases. The microstructure of the samples was investigated by using scanning electron microscopy (SEM), time-of-flight secondary ion mass spectroscopy (TOF-SIMS), transmission electron microscopy-based energy-dispersive spectroscopy (EDS) and electron energy loss spectroscopy (EELS), as well as X-ray diffraction (XRD) measurements. Based on the phases observed in different temperature ranges, a sequence of the phase transitions can be established, showing that in a realistic process, when freely cooling the sample with the furnace from high to room temperature, a microstructure having spinodal-like decomposition can also be expected. The elemental mapping and magnetic behaviors of this decomposed structure are also studied.

Synthesis of Well-Dispersed Copper Nanoparticles by L-Ascorbic Acid in Diethyleneglycol

2012 ◽  
Vol 549 ◽  
pp. 378-381 ◽  
Author(s):  
Jun Cheng Zhou ◽  
Wei He ◽  
Yao Tang ◽  
Yong Suan Hu
Keyword(s):  
Electron Microscopy ◽  
Ascorbic Acid ◽  
Copper Nanoparticles ◽  
Metallic Copper ◽  
Face Centered Cubic ◽  
X Ray Diffraction ◽  
Copper Particles ◽  
Transmission Electron ◽  
Face Centered ◽  
Fcc Structure

Metallic copper nanoparticles were synthesized in the presence of poly(N-vinylpyrrolidone) (PVP) as the capping agent and L-ascorbic acid as the reducing agent in diethyleneglycol (DEG) solvent. The obtained copper nanoparticles were characterized by scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), transmission electron microscopy (TEM) and X-ray diffraction (XRD). The EDS and XRD results showed that the resultant particles were confirmed to be crystalline Cu with a face-centered cubic (fcc) structure. It was also observed that the diameter of obtained copper particles ranging from 80 to 120nm via SEM and TEM.

scholarly journals Synthesis of Ag Nanostructures by Photochemical Reduction Using Citrate-Capped Pt Seeds

2011 ◽  
Vol 2011 ◽  
pp. 1-7 ◽  
Author(s):  
Hyeong-Ho Park ◽  
Xin Zhang ◽  
Yong-June Choi ◽  
Hyung-Ho Park ◽  
Ross H. Hill
Keyword(s):  
Average Diameter ◽  
Uv Exposure ◽  
Face Centered Cubic ◽  
X Ray Diffraction ◽  
Photochemical Reduction ◽  
X Ray ◽  
Transmission Electron ◽  
Visible Spectra ◽  
Uv Visible ◽  
Face Centered

A simple synthesis of Ag nanostructures such as nanorods and nanowires has been demonstrated with citrate-capped Pt seeds. UV-visible spectra and photographs of the synthesized solutions at different UV exposure times showed that the citrate-capped Pt seed played a crucial role in the growth of Ag nanostructures. After UV exposure of the colloidal solution for 60 min, the average diameter, length, and aspect ratio of the Ag nanostructures were about 95 nm, 2.1 μm, and 22, respectively. The photochemical reduction is hypothesized to result from photoelectron transfer from adsorbed citrate to Pt nanoparticle seed allowing Ag ions to form Ag nanostructures. Based on X-ray diffraction spectra and transmission electron microscope images, the synthesized Ag nanostructures were a face-centered cubic single crystal with good purity. These results suggest that the photochemical reduction method can provide Ag nanostructures in the presence of citrate-capped Pt seeds at room temperature for anisotropic Ag products.

The Microwave-Assisted Synthesis and Gas Sensing Properties for Ethanol of SnO2 Nanomaterials

2013 ◽  
Vol 721 ◽  
pp. 237-240 ◽  
Author(s):  
Yong Ju Liu ◽  
Qiu Ping Jiang ◽  
Yue Huan Li ◽  
He Yun Zhao
Keyword(s):  
Electron Microscopy ◽  
Gas Sensing ◽  
Microwave Assisted Synthesis ◽  
X Ray Diffraction ◽  
Sensing Properties ◽  
Microwave Assisted ◽  
Transmission Electron ◽  
Good Crystalline Quality ◽  
Gas Sensing Properties ◽  
Microwave Assisted Method

With the advantages of the microwave-assisted method, good crystalline quality SnO2nanomaterials were successfully synthesized. The morphology and microstructure of SnO2were characterized by X-ray diffraction (XRD), scanning electron microscopy, transmission electron microscopy and high-resolution (HRTEM) used to examine SnO2nanomaterials. Indirect-heating sensors based on nanorods were fabricated and investigated for the gas sensing properties to ethanol. The investigation demonstrates that the sensor based on prepared SnO2nanomaterials has good sensitivity, low detection limit and short response and reversion time to ethanol at 275 °C.

The Characterization and Gas Sensing Properties of Polythiophene Coated V2O5 Nanotubes

2010 ◽  
Vol 654-656 ◽  
pp. 1154-1157 ◽  
Author(s):  
Yu Lu ◽  
Wei Jin ◽  
Wen Chen
Keyword(s):  
Electron Microscopy ◽  
Gas Sensing ◽  
In Situ Polymerization ◽  
X Ray Diffraction ◽  
X Ray ◽  
Sensing Properties ◽  
Transmission Electron ◽  
Gas Sensing Properties ◽  
Higher Sensitivity

Polythiophene (PTP) coated V2O5 nanotubes were prepared by an in-situ polymerization of thiophene monomers in the presence of prepared V2O5 nanotubes. The nanotubes were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM), which proved the polymerization of thiophene monomer and the strong interaction between polythiophene and V2O5 nanotubes (VONTs). The gas sensing properties of PTP coated V2O5 nanotubes were studied at room temperature, which was found that PTP coated V2O5 nanotubes could detect ethanol with much higher sensitivity than pure VONTs. The sensing mechanism of PTP coated V2O5 nanotubes to ethanol is presumed to be the synergetic interaction between polythiophene (PTP) and V2O5 nanotubes.

Oxygen vacancies-contained SnO2 nanotubes with enhanced ethanol gas sensing properties

2019 ◽  
Vol 34 (01n03) ◽  
pp. 2040003 ◽  
Author(s):  
Yifan Chen ◽  
Xiuling Ma ◽  
Chen Li ◽  
Qiuyu Wu ◽  
Yongbo Wang ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
High Performance ◽  
Oxygen Vacancies ◽  
Gas Sensing ◽  
Original Sample ◽  
X Ray Diffraction ◽  
Sensing Properties ◽  
Transmission Electron ◽  
Gas Sensing Properties ◽  
Ethanol Sensing

[Formula: see text] porous nanotubes containing oxygen vacancies were prepared by electron spinning and H plasma treatment. The morphology and crystal structure of the samples were analyzed by scanning electron microscopy (SEM), transmission electron microscopy (TEM) and X-ray diffraction (XRD). The ethanol-sensing properties of the [Formula: see text] sensor were tested. The results show that the samples treated with H plasma for 20 min have the best performance. Its working temperature is [Formula: see text]C lower than [Formula: see text]C of the original sample, with a sensitivity of 17 at 100 ppm, which is seven times higher than the original sample. It also shows good selectivity to some common interfering gases. This enhancement can be ascribed to the introduced oxygen vacancy. This work provides an efficient way to design high-performance gas sensor materials.

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