scholarly journals Sensitive detection of hydrocarbon gases using electrochemically Pd-modified ZnO chemiresistors

2017 ◽  
Vol 8 ◽  
pp. 82-90 ◽  
Author(s):  
Elena Dilonardo ◽  
Michele Penza ◽  
Marco Alvisi ◽  
Gennaro Cassano ◽  
Cinzia Di Franco ◽  
...  
Keyword(s):  
Gas Sensors ◽  
Photoelectron Spectroscopy ◽  
Zno Nanorods ◽  
Hydrocarbon Chain ◽  
Pd Nanoparticles ◽  
Hydrocarbon Gases ◽  
X Ray ◽  
Gas Molecule ◽  
The Mean ◽  
Chemiresistive Gas Sensors

Pristine and electrochemically Pd-modified ZnO nanorods (ZnO NRs) were proposed as active sensing layers in chemiresistive gas sensors for hydrocarbon (HC) gas detection (e.g., CH4, C3H8, C4H10). The presence of Pd nanoparticles (NPs) on the surface of ZnO NRs, obtained after the thermal treatment at 550 °C, was revealed by morphological and surface chemical analyses, using scanning electron microscopy and X-ray photoelectron spectroscopy, respectively. The effect of the Pd catalyst on the performance of the ZnO-based gas sensor was evaluated by comparing the sensing results with those of pristine ZnO NRs, at an operating temperature of 300 °C and for various HC gas concentrations in the range of 30–1000 ppm. The Pd-modified ZnO NRs showed a higher selectivity and sensitivity compared to pristine ZnO NRs. The mean sensitivity of Pd-modified ZnO NRs towards the analyzed HCs gases increased with the length of the hydrocarbon chain of the target gas molecule. Finally, the evaluation of the selectivity revealed that the presence or the absence of metal nanoparticles on ZnO NRs improves the selectivity in the detection of specific HCs gaseous molecules.

A Two-step Electrodeposition of Pd-Cu/Cu2O Nanocomposite on FTO Substrate for Non-enzymatic Hydrogen Peroxide Sensor

2021 ◽  
Vol 17 ◽  
Author(s):  
Ke Huan ◽  
Li Tang ◽  
Dongmei Deng ◽  
Huan Wang ◽  
Xiaojing Si ◽  
...  
Keyword(s):  
Hydrogen Peroxide ◽  
Cyclic Voltammetry ◽  
Photoelectron Spectroscopy ◽  
Chemical Structure ◽  
Pd Nanoparticles ◽  
Optimal Conditions ◽  
Potential Oscillation ◽  
X Ray Diffraction ◽  
X Ray

Background: Hydrogen peroxide (H2O2) is a common reagent in the production and living, but excessive H2O2 may enhance the danger to the human body. Consequently, it is very important to develop economical, fast and accurate techniques for detecting H2O2. Methods: A simple two-step electrodeposition process was applied to synthesize Pd-Cu/Cu2O nanocomposite for non-enzymatic H2O2 sensor. Cu/Cu2O nanomaterial was firstly electrodeposited on FTO by potential oscillation technique, and then Pd nanoparticles were electrodeposited on Cu/Cu2O nanomaterial by cyclic voltammetry. The chemical structure, component, and morphology of the synthesized Pd-Cu/Cu2O nanocomposite were characterized by X-ray diffraction, scanning electron microscopy and X-ray photoelectron spectroscopy. The electrochemical properties of Pd-Cu/Cu2O nanocomposite were studied by cyclic voltammetry and amperometry. Results: Under optimal conditions, the as-fabricated sensor displayed a broad linear range (5-4000 µM) and low detection limit (1.8 µM) for the determination of H2O2. The proposed sensor showed good selectivity and reproducibility. Meanwhile, the proposed sensor has been successfully applied to detect H2O2 in milk. Conclusion: The Pd-Cu/Cu2O/FTO biosensor exhibits excellent electrochemical activity for H2O2 reduction, which has great potential application in the field of food safety.

scholarly journals Origin of the surface recombination centers in ZnO nanorods arrays by X-ray photoelectron spectroscopy

2010 ◽  
Vol 256 (11) ◽  
pp. 3592-3597 ◽  
Author(s):  
L.L. Yang ◽  
Q.X. Zhao ◽  
M. Willander ◽  
X.J. Liu ◽  
M. Fahlman ◽  
...  
Keyword(s):  
Photoelectron Spectroscopy ◽  
Zno Nanorods ◽  
Surface Recombination ◽  
X Ray ◽  
Recombination Centers

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.

Cation exchange in synthetic manganates: II. The structure of an alkylammonium-saturated phyllomanganate

Clay Minerals ◽  
1986 ◽  
Vol 21 (5) ◽  
pp. 957-964 ◽  
Author(s):  
E. Paterson ◽  
D.R. Clark ◽  
D. Russell ◽  
R. Swaffield
Keyword(s):  
Chain Length ◽  
Photoelectron Spectroscopy ◽  
Hydrocarbon Chain ◽  
Exchange Capacity ◽  
Basal Spacing ◽  
Water Molecules ◽  
Interlayer Water ◽  
X Ray ◽  
Alkyl Chains ◽  
Hydrocarbon Chain Length

AbstractA synthetic phyllomanganate saturated with a series of primary alkylammonium cations has been examined using XRD, chemical analysis and X-ray photoelectron spectroscopy. A linear relationship exists between the basal spacing of the saturated alkylammonium-manganate and the hydrocarbon chain length in the interlayer, and from the gradient it is concluded that the alkyl chains are perpendicular to the manganate sheet. This orientation is a function of both the charge density and the presence of a layer of water molecules immediately adjacent to the manganate basal surfaces. Evacuation results in the loss of this interlayer water and the structure of the organo-manganate is considerably disrupted. The extent to which the interlayer arrangement can be reinstated by rehydration is dependent on the chain length of the saturating organo-cation. For cations of chain length > C6 the C contents suggest that cation in excess of the exchange capacity is present in the interlayer, but the absence of any compensating anion and the release of amine on evacuation suggests that the excess C arises from the presence of free amine.

scholarly journals Fabrication of Hybrid Catalyst ZnO Nanorod/α-Fe2O3 Composites for Hydrogen Evolution Reaction

Crystals ◽  
2020 ◽  
Vol 10 (5) ◽  
pp. 356
Author(s):  
Kasimayan Uma ◽  
Elavarasan Muniranthinam ◽  
Siewhui Chong ◽  
Thomas C.-K Yang ◽  
Ja-Hon Lin
Keyword(s):  
Hydrogen Evolution ◽  
Hydrogen Evolution Reaction ◽  
Photoelectron Spectroscopy ◽  
Electrochemical Impedance ◽  
Nickel Foam ◽  
Zno Nanorods ◽  
Synergetic Effect ◽  
Zno Nanorod ◽  
Fe2o3 Nanoparticles ◽  
X Ray

This report presents the synthesis of ZnO nanorod/α-Fe2O3 composites by the hydrothermal method with different weight percentages of α-Fe2O3 nanoparticles. The as-synthesized nanorod composites were characterized by different techniques, such as X-ray diffraction (XRD), Fourier transform-infrared (FT-IR), field emission scanning electron microscopy (FE-SEM), electrochemical impedance spectroscopy (EIS), and X-ray photoelectron spectroscopy (XPS). From our results, it was found that the ZnO/α-Fe2O3 (3 wt%) nanorod composites exhibit a higher hydrogen evolution reaction (HER) activity when compared to other composites. The synergetic effect between ZnO and (3 wt%) of α-Fe2O3 nanocomposites resulted in a low onset potential of −125 mV, which can effectively produce more H2 than pure ZnO. The H2 production rate over the composite of ZnO/α-Fe2O3 (3 wt%) clearly shows a significant improvement in the photocatalytic activity in the heterojunction of the ZnO nanorods and α-Fe2O3 nanoparticles on nickel foam.

scholarly journals Synthesis and Characterization of Heterostructure Pd/Bi2WO6 Nanocomposites with Enhanced Properties of Visible-Light-Driven Photocatalyst

2021 ◽  
Author(s):  
Anukorn Phuruangrat ◽  
Jarupat Teppetcharat ◽  
Panudda Patiphatpanya ◽  
Phattranit Dumrongrojthanath ◽  
Somchai Thongtem ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Visible Light ◽  
Photoelectron Spectroscopy ◽  
Pd Nanoparticles ◽  
Cubic Phase ◽  
Xenon Lamp ◽  
Visible Absorption ◽  
X Ray ◽  
Visible Light Driven ◽  
20 Nm

Abstract Heterostructure Pd/Bi2WO6 nanocomposites were successful synthesized in ethylene glycol by microwave-assisted deposition method at 300 W for 10 min. Effect of the loaded Pd on phase, composition, morphology and visible-light-driven photocatalytic properties of Bi2WO6 was investigated by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), Fast-Fourier-Transform (FFT) diffraction, UV-visible absorption and X-ray photoelectron spectroscopy (XPS). In this research, good distribution of cubic phase of spherical Pd nanoparticles with particle size of 15–20 nm supported on orthorhombic Bi2WO6 thin nanoplates. The 10% Pd/Bi2WO6 nanocomposites reveal major metallic Pd0 species containing in Bi2WO6 sample. Microwave can be used to synthesize metallic Pd nanoparticles supporting on top of Bi2WO6 nanoplates. Photocatalytic activities of Bi2WO6 loaded with different weight contents of Pd were monitored through photodegradation of cationic rhodamine B (RhB) dye under visible light irradiation of a xenon lamp. The 10% Pd/Bi2WO6 nanocomposites have the highest photocatalytic activity because Pd nanoparticles as electron acceptors promote interfacial charge-transfer through Pd/Bi2WO6 heterojunction.

scholarly journals Promising Cr-Doped ZnO Nanorods for Photocatalytic Degradation Facing Pollution

2021 ◽  
Vol 12 (1) ◽  
pp. 34
Author(s):  
Fatemah. H. Alkallas ◽  
Amira Ben Gouider Trabelsi ◽  
Ramzi Nasser ◽  
Susana Fernandez ◽  
Ji-Ming Song ◽  
...  
Keyword(s):  
Photoelectron Spectroscopy ◽  
Zno Nanorods ◽  
Hexagonal Structure ◽  
Oh Radicals ◽  
Light Illumination ◽  
Interstitial Oxygen ◽  
X Ray Diffraction ◽  
Kinetic Rate Constant ◽  
X Ray ◽  
Transmission Electron

Chromium (Cr)-doped zinc oxide (ZnO) nanorods with wurtzite hexagonal structure were prepared through a thermal decomposition technique. The concentration effect of the Cr doping on the structural, morphological, and optical properties of the ZnO nanorods was established by correlating various measurements: transmission electron microscopy (TEM), photoluminescence (PL), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and several UV-visible studies. The obtained nanorods were investigated as photocatalysts for the photodegradation process of methyl orange (MO), under UV-vis light illumination. Different weights and time intervals were studied. A 99.8% photodegradation of MO was obtained after 100 min in the presence of 1 wt.% Cr III acetate hydroxide and zinc acetate dehydrate “ZnO-Cr1”. The kinetic rate constant of the reaction was found to be equal to 4.451 × 10−2 min−1 via a pseudo-first order rate model. Scavenger radicals demonstrated the domination of OH• radicals by those of O2•− superoxide species during the photodegradation. The interstitial oxygen site Oi is proposed to play a key role in the generation of holes in the valence band under visible irradiation. The ZnO-Cr1 photocatalyst displayed good cycling stability and reusability.

scholarly journals Low Working Temperature of ZnO-MoS2 Nanocomposites for Delaying Aging with Good Acetylene Gas-Sensing Properties

Nanomaterials ◽  
2020 ◽  
Vol 10 (10) ◽  
pp. 1902
Author(s):  
Sijie Wang ◽  
Weigen Chen ◽  
Jian Li ◽  
Zihao Song ◽  
He Zhang ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Gas Sensors ◽  
Photoelectron Spectroscopy ◽  
Gas Sensing ◽  
Morphological Characteristics ◽  
Molar Ratio ◽  
X Ray ◽  
Sensing Properties ◽  
Working Temperature ◽  
Current Concerns

The long-term stability and the extension of the use time of gas sensors are one of the current concerns. Lowering the working temperature is one of the most effective methods to delay aging. In this paper, pure MoS2 and ZnO-MoS2 nanocomposites were successfully prepared by the hydrothermal method, and the morphological characteristics were featured by scanning electron microscopy (SEM), X-ray diffraction (XRD), transmission electron microscopy (TEM) and X-ray photoelectron spectroscopy (XPS). Pure MoS2 and ZnO-MoS2 nanocomposites, as a comparison, were used to study the aging characteristic. The sensing properties of the fabricated gas sensors with an optimal molar ratio ZnO-MoS2 (Zn:Mo = 1:2) were recorded, and the results exhibit a high gas-sensing response and good repeatability to the acetylene detection. The working temperature was significantly lower than for pure MoS2. After aging for 40 days, all the gas-sensing response was relatively attenuated, and pure MoS2 exhibits a faster decay rate and lower gas-sensing response than nanocomposites. The better gas-sensing characteristic of nanocomposites after aging was possibly attributed to the active interaction between ZnO and MoS2.

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