scholarly journals Generation of Porous Alumina Layers in a Polydimethylsiloxane/Hydrogen Peroxide Medium on Aluminum Substrate in Corona Discharges

2014 ◽  
Vol 2014 ◽  
pp. 1-6 ◽  
Author(s):  
A. Groza ◽  
A. Surmeian ◽  
C. Diplasu ◽  
C. Luculescu ◽  
C. Negrila ◽  
...  
Keyword(s):  
Hydrogen Peroxide ◽  
Photoelectron Spectroscopy ◽  
Atmospheric Pressure ◽  
Porous Alumina ◽  
Aluminum Substrate ◽  
Corona Discharges ◽  
Negative Corona ◽  
Alumina Layer ◽  
X Ray ◽  
Anodization Process

The porous alumina (Al2O3) layer obtained at the interface between polydimethylsiloxane/hydrogen peroxide medium and aluminum substrate under charged and neutral species injection produced in negative corona discharges in air at atmospheric pressure is analyzed by different methods in this paper. The scanning electron microscopy investigations showed the uniform distribution of the pores formed in the alumina layer and their columnar structures. Both energy dispersive X-ray spectroscopy (EDS) and X-ray photoelectron spectroscopy (XPS) measurements indicate that during the anodization process of the aluminum in the polydimethylsiloxane/hydrogen peroxide medium in corona discharge the incorporation of silicon in the structure of the alumina layer is possible.

Nitriding of yttria-stabilized zirconia in atmospheric pressure microwave plasma

2009 ◽  
Vol 24 (6) ◽  
pp. 2021-2028 ◽  
Author(s):  
R. Milani ◽  
R.P. Cardoso ◽  
T. Belmonte ◽  
C.A. Figueroa ◽  
C.A. Perottoni ◽  
...  
Keyword(s):  
Photoelectron Spectroscopy ◽  
Atmospheric Pressure ◽  
Microwave Plasma ◽  
Plasma Nitriding ◽  
Nitrided Layer ◽  
Zirconium Nitride ◽  
Stabilized Zirconia ◽  
Partially Stabilized Zirconia ◽  
X Ray ◽  
Yttria Partially Stabilized Zirconia

High temperature plasma nitriding of yttria-partially-stabilized zirconia in atmospheric pressure microwave plasma was investigated. The morphological, mechanical, and physicochemical characteristics of the resulting nitrided layer were characterized by different methods, such as optical and scanning electron microscopy, microindentation, x-ray diffraction, narrow resonant nuclear reaction profiling, secondary neutral mass spectrometry, and x-ray photoelectron spectroscopy, aiming at investigating the applicability of this highly efficient process for nitriding of ceramics. The structure of the plasma nitrided layer was found to be complex, composed of tetragonal and cubic zirconia, as well as zirconium nitride and oxynitride. The growth rate of the nitrided layer, 4 µm/min, is much higher than that obtained by any other previous nitriding process, whereas a typical 50% increase in Vickers hardness over that of yttria-partially-stabilized zirconia was observed.

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 Facile Fabrication of Metal Oxide Based Catalytic Electrodes by AC Plasma Deposition and Electrochemical Detection of Hydrogen Peroxide

Catalysts ◽  
2019 ◽  
Vol 9 (11) ◽  
pp. 888 ◽  
Author(s):  
Quang-Tan Bui ◽  
In-Keun Yu ◽  
Anantha Iyengar Gopalan ◽  
Gopalan Saianand ◽  
Woonjung Kim ◽  
...  
Keyword(s):  
Hydrogen Peroxide ◽  
Metal Oxide ◽  
Photoelectron Spectroscopy ◽  
Electrode Materials ◽  
Plasma Deposition ◽  
Metal Oxide Nanoparticles ◽  
Modified Electrodes ◽  
Precursor Solution ◽  
X Ray ◽  
Cuo Nps

In this study, the fabrication of a metal oxide nanoparticles (NPs) dispersed catalytic electrode is described based on a new alternating current (AC) plasma deposition approach. The fabrication involves the treatment of AC plasma on a precursor solution comprised of metal salts such as CuCl2, FeCl2, and ZnCl2, and a monomer (acrylic acid) in the presence/absence of a cross-linker. Furthermore, the utility of such developed electrodes has been demonstrated for the electrochemical determination of hydrogen peroxide (H2O2). The electrode materials obtained through plasma treatment was characterized by Fourier transform infrared (FT-IR) spectroscopy, scanning electron microscope (SEM), contact angle measurements, energy-dispersive X-ray spectroscopy (EDS), X-ray photoelectron spectroscopy (XPS), and cyclic voltammetry. Among the metal oxide modified electrodes prepared by the AC plasma deposition method, the copper oxide (CuO) NPs catalytic electrode exhibited significant oxidation and reduction peaks for H2O2 in phosphate-buffered saline solution. The catalytic electrode with CuO NPs exhibited a combination of good H2O2 sensing characteristics such as good sensitivity (63.52 mA M−1 cm−2), good selectivity, low detection limits (0.6 µM), fast sensing response (5 s), a wide linear range (0.5–8.5 mM), and good stability over 120 cycles. Based on our results, it is well demonstrated that plasma deposition could be effectively utilized for the fabrication of the catalytic electrode for detection of H2O2 concentrations. Further, the strategy of using AC plasma for fabrication of metal oxide-based modified electrodes could also be extended for the fabrication of other kinds of nanomaterials-based sensors.

Chemical Vapor Deposition of Niobium Carbide using a Novel Organometallic Precursor.

1989 ◽  
Vol 168 ◽  
Author(s):  
Paul D. Stupik ◽  
Linda K. Cheatham ◽  
John J. Graham ◽  
Andrew R. Barron
Keyword(s):  
Chemical Vapor Deposition ◽  
Vapor Deposition ◽  
Photoelectron Spectroscopy ◽  
Atmospheric Pressure ◽  
Niobium Carbide ◽  
Chemical Vapor ◽  
Stoichiometric Ratio ◽  
X Ray ◽  
Organometallic Precursor ◽  
Scanning Electron

AbstractChemical vapor deposition from (MeCp)2Nb(allyl) at atmospheric pressure yields niobium carbide films at temperatures as low as 300°C. X-ray photoelectron spectroscopy (XPS) studies indicate that the bulk films contain a carbide phase and a nearly stoichiometric ratio of niobium to carbon. The morphology of the films has been examined by scanning electron microscopy (SEM).

scholarly journals XPS studies of the surface of TiO2:Ag nanopowders

2020 ◽  
Vol 11 (4) ◽  
pp. 547-555
Author(s):  
O. M. Korduban ◽  
◽  
T. V. Kryshchuk ◽  
V. O. Kandyba ◽  
V. V. Trachevskii ◽  
...  
Keyword(s):  
Hydrogen Peroxide ◽  
Photoelectron Spectroscopy ◽  
Lattice Distortion ◽  
Orbit Splitting ◽  
Xps Spectra ◽  
X Ray ◽  
Annealing Conditions ◽  
Oxide Hydroxide ◽  
Spin Orbit Splitting ◽  
Titanium Wire

n-TiO2 and n-TiO2:Ag nanopowders were synthesized by the method of electric explosion of wires (EEW). The doping of nanopowders took place during the explosion of titanium wire, on the surface of which an Ag2O layer of the appropriate mass was applied. The energy of the explosion was equal to Е = 3.1·Еs, where Es is the energy of sublimation of the metal. Based on the synthesized nanopowders, mesoporous n-TiO2 and n-TiO2:Ag films were formed. The phase composition of the surface of several series of n-TiO2 and n-TiO2:Ag samples under different annealing conditions was studied by X-ray photoelectron spectroscopy. The XPS spectra of the Ti2p- and Ag3d- levels were decomposed by the Gauss-Newton method into interconnected components 2p3/2/2p1/2 and 3d5/2/3d3/2 with parameters DЕ = 5.76 eV; I1/I2 = 0.5 and DЕ = 6.0 eV; I1/I2 = 0.66 to take into account the spin-orbit splitting of the pair respectively. The paper presents histograms of the contributions of the components to the Ti2p- and Ag3d- spectra, which vary depending on the degree of doping and annealing conditions for 4 series of samples. According to XPS data, on the surface of EEW nanopowders TiO2 and TiO2:Ag titanium is represented by Ti3+- and Ti4+- states, silver by Ag0-, Ag1+- and Ag2+- states. In all series of samples, the contribution of the Ti3+- state simultaneously increases with an increase in the absolute Ag content, which is a consequence of the lattice distortion through the formation of a surface phase with Ti–O–Ag bonds. Annealing at 300 °C in air leads to an increase in the contribution to the spectra of Ti4+- states of ЕbTi2p3/2 = 458.3 eV and Ag1+ - states. Pretreatment of the samples with hydrogen peroxide before annealing leads to an increase in the contribution of oxide-hydroxide phases of titanium and Ag0- states. Annealing of the samples at 300 °С in argon with pretreatment with hydrogen peroxide leads to an increase in the contribution to the spectra of Ti4+- states with ЕbTi2p3/2 = 458.8 eV, oxide-hydroxide phases of titanium and Ag0. It has been found that the direction of redox processes on the surface of n-TiO2 after the action of H2O2 and subsequent annealing in air depends on the state of hydration of the original nanopowders.

scholarly journals Selective Growth of Al2O3 on Size-Selected Platinum Clusters by Atomic Layer Deposition

2019 ◽  
Author(s):  
Timothy J. Gorey ◽  
Yang Dai ◽  
Scott Anderson ◽  
Sungsik Lee ◽  
Sungwon Lee ◽  
...  
Keyword(s):  
Atomic Layer Deposition ◽  
Photoelectron Spectroscopy ◽  
High Vacuum ◽  
Atomic Layer ◽  
Ultra High Vacuum ◽  
Ex Situ ◽  
Dimensional Structure ◽  
Alumina Layer ◽  
X Ray ◽  
Layer Deposition

In heterogeneous catalysis, atomic layer deposition (ALD) has been developed as a tool to stabilize and reduce carbon deposition on supported nanoparticles. Here, we discuss use of high vacuum ALD to deposit alumina films on size-selected, sub-nanometer Pt/SiO2 model catalysts. Mass-selected Pt24 clusters were deposited on oxidized Si(100), to form model Pt24/SiO2 catalysts with particles shown to be just under 1 nm, with multilayer three dimensional structure. Alternating exposures to trimethylaluminum and water vapor in an ultra-high vacuum chamber were used to grow alumina on the samples without exposing them to air. The samples were probed in situ using X-ray photoelectron spectroscopy (XPS), low-energy ion scattering spectroscopy (ISS), and CO temperature-programmed desorption (TPD). Additional samples were prepared for ex situ experiments using grazing incidence small angle x-ray scattering spectroscopy (GISAXS). Alumina growth is found to initiate at least 60 times more efficiently at the Pt24 cluster sites, compared to bare SiO2/Si, with a single ALD cycle depositing a full alumina layer on top of the clusters, with substantial additional alumina growth initiating on SiO2 sites surrounding the clusters. As a result, the clusters were completely passivated, with no exposed Pt binding sites.

ELECTROCHEMICAL Co3O4 NANOPOROUS THIN FILMS SENSOR FOR HYDROGEN PEROXIDE DETECTION

NANO ◽  
2014 ◽  
Vol 09 (04) ◽  
pp. 1450047 ◽  
Author(s):  
GUANG SHENG CAO ◽  
RUILIN WANG ◽  
PEILONG WANG ◽  
XIN LI ◽  
YUE WANG ◽  
...  
Keyword(s):  
Thin Films ◽  
Hydrogen Peroxide ◽  
Tin Oxide ◽  
Indium Tin Oxide ◽  
Photoelectron Spectroscopy ◽  
Electrode Materials ◽  
Electrochemical Sensing ◽  
Detection Sensitivity ◽  
X Ray ◽  
Hydrogen Peroxide Detection

The nanoporous Co 3 O 4 thin films were prepared on indium tin oxide (ITO) glasses by an electrodeposition method. The surface morphology and composition of the nanoporous Co 3 O 4 films were characterized by scanning electron microscopy (SEM), energy-dispersive X-ray analysis (EDS) and X-ray photoelectron spectroscopy (XPS). The results show that the as-deposited nanoporous Co 3 O 4 film is constructed by many interconnected nanoflakes with thickness of about 40 nm. The cyclic voltammetry (CV) measurement indicates that the nanoporous Co 3 O 4 films exhibit remarkable electrocatalytic activities for the hydrogen peroxide ( H 2 O 2) reduction which shows that it is a good candidate to be employed as electrode materials for electrochemical sensing of H 2 O 2. Further analysis indicated that the detection sensitivity of the sensor was 1.357 mA mM-1 cm-2 and the detection limit was estimated to be about 0.2 mM.

Surface analysis of a heat-treated, Al-containing, iron-based superalloy

1998 ◽  
Vol 13 (12) ◽  
pp. 3411-3416 ◽  
Author(s):  
M. F. López ◽  
A. Gutiéerrez ◽  
M. C. García-Alonso ◽  
M. L. Escudero
Keyword(s):  
Heat Treatment ◽  
Photoelectron Spectroscopy ◽  
Surface Composition ◽  
Passive Layer ◽  
Alumina Layer ◽  
Outward Diffusion ◽  
Xps Spectra ◽  
X Ray ◽  
Heat Treated ◽  
Layer Iron

The surface composition of MA 956 superalloy both as-received and after four exposure times at 1100 °C has been investigated by energy dispersive x-ray spectrometry (EDX) and x-ray photoelectron spectroscopy (XPS). The passive layer of the as-received sample is mainly formed by Cr- and Fe-oxides. Heat treatment leads to the formation of an alumina layer on which small nodules grow. XPS spectra evidence the presence of titanium and yttrium oxides at the surface of the heat-treated samples, suggesting Y and Ti outward diffusion through the alumina layer. Iron and chromium oxides at the topmost surface layers are observed only for short heat-treatment times.

scholarly journals Removal of nitrate from water by acid-washed zero-valent iron/ferrous ion/hydrogen peroxide: influencing factors and reaction mechanism

2017 ◽  
Vol 77 (2) ◽  
pp. 525-533 ◽  
Author(s):  
Yongye Li ◽  
Fenglian Fu ◽  
Zecong Ding
Keyword(s):  
Hydrogen Peroxide ◽  
Reaction Mechanism ◽  
Photoelectron Spectroscopy ◽  
Nitrate Reduction ◽  
Nitrate Removal ◽  
Zero Valent Iron ◽  
Ferrous Ion ◽  
Combined System ◽  
X Ray ◽  
Before And After

Abstract In this paper, a system consisting of acid-washed zero-valent iron (ZVI), ferrous ion (Fe2+), and hydrogen peroxide (H2O2) was employed for the removal of nitrate (NO3−) from water, and the reaction mechanism for this is discussed. The effects of acid-washed ZVI, Fe2+, H2O2, and initial NO3− concentration on nitrate removal were investigated. Acid-washed ZVI before and after reaction with nitrate were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS). Results reveal that the combined system can enhance the corrosion of ZVI and facilitate aqueous nitrate reduction. The products of nitrate reduction are mainly ammonium, with some N2. The ZVI particles after reaction may have a core of ZVI with an oxidation layer mainly consisting of Fe3O4.

scholarly journals Preparation of Pd/C by Atmospheric-Pressure Ethanol Cold Plasma and Its Preparation Mechanism

Nanomaterials ◽  
2019 ◽  
Vol 9 (10) ◽  
pp. 1437 ◽  
Author(s):  
Zhuang Li ◽  
Jingsen Zhang ◽  
Hongyang Wang ◽  
Zhihui Li ◽  
Xiuling Zhang ◽  
...  
Keyword(s):  
Co Oxidation ◽  
Photoelectron Spectroscopy ◽  
Atmospheric Pressure ◽  
High Performance ◽  
Cold Plasma ◽  
Carbon Layer ◽  
X Ray ◽  
Catalytic Materials ◽  
Ethanol Decomposition ◽  
Ar Gas

Treatment with atmospheric-pressure (AP) hydrogen cold plasma is an effective method for preparing highly active supported metal catalytic materials. However, this technique typically uses H2 as working gas, which is explosive and difficult to transport. This study proposes the use of PdCl2 as a Pd precursor and activated carbon as the support to fabricate Pd/C catalytic materials (Pd/C-EP-Ar) by using ethanol—which is renewable, easily stored, and safe—combined with AP cold plasma (AP ethanol cold plasma) followed by calcination in Ar gas at 550 °C for 2 h. Both Pd/C-EP and Pd/C-HP fabricated using AP ethanol and hydrogen cold plasma (without calcination in Ar gas) respectively, exhibit low CO oxidation reactivity. The activity of Pd/C-EP is lower than Pd/C-HP, which is mainly ascribed to the carbon layer formed by ethanol decomposition during plasma treatment. However, the 100% CO conversion temperature (T100) of Pd/C-EP-Ar is 140 °C, which is similar to that of Pd/C-HP-Ar fabricated using AP hydrogen cold plasma (calcined in Ar gas at 550 °C for 2 h). The characterization results of X-ray diffraction, X-ray photoelectron spectroscopy, and transmission electron microscopy indicated that the carbon layer formed by ethanol decomposition enhanced the interaction of metal nanoparticles to the support, and a high Pd/C atomic ratio was obtained. This was beneficial to the high CO oxidation performance. This work provides a safe method for synthesizing high-performance Pd/C catalytic materials avoiding the use of H2, which is explosive and difficult to transport.

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