scholarly journals Electrochemical behavior of Ag-Cu alloy in alkaline media

2010 ◽  
Vol 64 (2) ◽  
pp. 105-110 ◽  
Author(s):  
Vesna Grekulovic ◽  
Mirjana Rajcic-Vujasinovic ◽  
Zoran Stevic
Keyword(s):  
Electrochemical Behaviour ◽  
Pure Copper ◽  
Alkaline Media ◽  
Alkaline Solutions ◽  
Cyclic Voltammograms ◽  
Pure Silver ◽  
Cu Alloy ◽  
Current Densities ◽  
Wide Potential

Results of the investigation of electrochemical behaviour of Ag-Cu alloy containing 50 mass% Ag and 50 mass% Cu are presented in this paper. Pure silver and copper were investigated, too. Working electrodes were prepared by metallurgical process. 1 mol dm-3 and 0.5 mol dm-3 solutions of NaOH are chosen as the electrolyte. On the cyclic voltammograms, some current waves corresponding to number and quantity of phases present in the investigated electrodes appeared and they can be used for characterization of investigated alloy. On the voltammogram recorded for pure silver, two anodic and two cathodic peaks appeared. First peak consisted of two joined current waves which can be ascribed to the formation of the two different types of silver(I) oxide, Ag2O. Second peak should correspond to the formation of silver(II) oxide, AgO. Voltammogram obtained for pure copper exhibits one broad current wave corresponding to the formation of copper oxides, followed by a wide potential area in which copper is completely passive. At 0.4 V vs. SCE, current starts to increase again due to oxygen evolution and probably due to simultaneous dissolution of copper with formation of CuO22- as a product. In alkaline solutions copper has no significant influence on the shape and current values of the voltammograms recorded for Ag-Cu alloy; however, it has an influence only on the anodic and cathodic peak potentials, which are shifted to more negative values in comparison to Ag. It could mean an easier formation of oxides and their harder reduction. Comparing voltammograms recorded for Ag-Cu alloy in 0.5 moldm-3 NaOH and in 1 moldm-3 NaOH solutions, one can see that current waves appear at more positive potentials on the voltammograms obtained in the solution of lower concentration and with much higher current densities than those on the voltammograms obtained in the solution of higher concentration.

scholarly journals Electrochemical behavior of AgCu50 in alkaline media in the presence of chlorides and 2-mercaptobenzothiazole

2017 ◽  
Vol 53 (3) ◽  
pp. 349-356 ◽  
Author(s):  
V. Grekulovic ◽  
M. Rajcic-Vujasinovic ◽  
A. Mitovski
Keyword(s):  
Electrochemical Behavior ◽  
Electrode Surface ◽  
Anodic Polarization ◽  
Pure Copper ◽  
Inhibitory Effect ◽  
Open Circuit ◽  
Alkaline Media ◽  
Nacl Solution ◽  
Pure Silver ◽  
Current Densities

Electrochemical behavior of an alloy AgCu50, pure copper, and pure silver, respectively, was investigated by measuring the open circuit potentials using anodic potentiodynamic polarization and potentiostatic method in 0.1 moldm-3 NaOH + 0.02 moldm-3 NaCl solution, without and with adding 2-mercaptobenzothiazole in various concentrations (0.00001 - 0.001 moldm-3). Anodic polarization curves for AgCu50 alloy, showed four current peaks. Potentiostatic curves showed that values of the stationary current densities drop down with the increase of 2-mercaptobenzothiazole concentration in the electrolyte. The electrode surface was analyzed by optical microscopy after the potentiostatic oxidation. Micrographs confirmed that 2-mercaptobenzothiazole has got the inhibitory effect by forming the film of CuMBT and AgMBT which protect the electrode surface from corrosion.

scholarly journals Synthesis and physicochemical characterization of chemically modified chitosan by succinic anhydride

2006 ◽  
Vol 49 (4) ◽  
pp. 665-668 ◽  
Author(s):  
Karine Gargioni Pereira Correa de Mello ◽  
Leandra de Cássia Bernusso ◽  
Ronaldo Nogueira de Moraes Pitombo ◽  
Bronislaw Polakiewicz
Keyword(s):  
Succinic Anhydride ◽  
Physicochemical Characterization ◽  
Alkaline Media ◽  
Alkaline Solutions ◽  
Water Molecules ◽  
Alkyl Chains ◽  
Modified Chitosan ◽  
Chemically Modified ◽  
New Applications

The N-succinil-chitosan is a chemically modified derivative of the biopolymer chitosan. The succinic anhydride attached to the free amino groups presented along the chitosan's polymer chain imparts to the molecule different physicochemical properties not exhibited before the modification. These chemical modifications enhance chitosan's solubility in slightly acid, neutral and alkaline media. These properties are related to the long alkyl chains attached to hydrophilic parts. In this case the hydrophilic part of D-glucosamine promotes stronger interactions with the water molecules, and consequently, enhances the solubility of the chitosan polymer. Non-modified free chitosan is soluble only in acidic medium (pH < 5.5). These modifications made possible new applications of chitosan in biotechnological area since the solubility in neutral or slightly alkaline solutions is very important in a biological field.

Mn-Mo-O Catalysts for Methanol Oxidation. I. Preparation and Characterization of the Catalysts

1992 ◽  
Vol 57 (12) ◽  
pp. 2529-2538 ◽  
Author(s):  
Krasimir Ivanov ◽  
Penka Litcheva ◽  
Dimitar Klissurski
Keyword(s):  
Methanol Oxidation ◽  
Solution Concentration ◽  
Alkaline Media ◽  
Acidic Media ◽  
Chemical Methods ◽  
X Ray ◽  
Ph Values ◽  
Precipitate Composition

Mn-Mo-O catalysts with a different Mo/Mn ratio have been prepared by precipitation. The precipitate composition as a function of solution concentration and pH was studied by X-ray, IR, thermal and chemical methods. Formation of manganese molybdates with MnMoO4.1.5H2O, Mn3Mo3O12.2.5H2O, and Mn3Mo4O15.4H2O composition has been supposed. It is concluded that pure MnMoO4 may be obtained in both acid and alkaline media, the pH values depending on the concentration of the initial solutions. The maximum Mo/Mn ratio in the precipitates is 1.33. The formation of pure Mn3Mo4O15.4H2O is possible in weakly acidic media. This process is favoured by increasing the concentration of initial solutions.

Stability and Microstructure Characterization of Barrierless Cu (Sn, C) Films

2014 ◽  
Vol 1052 ◽  
pp. 163-168 ◽  
Author(s):  
Xiao Na Li ◽  
Lu Jie Jin ◽  
Li Rong Zhao ◽  
Chuang Dong
Keyword(s):  
Diffusion Barrier ◽  
Amorphous Layer ◽  
Barrier Effect ◽  
Co Doping ◽  
Cu Alloy ◽  
Large Atom ◽  
Cu Film ◽  
Small Atom ◽  
Lower Resistivity

Thermal stability, adhesion and electronic resistivity of the Cu alloy films with diffusion barrier elements (large atom Sn and small atom C) have been studied. Ternary Cu (0.6 at.% Sn, 2 at.% C) films were prepared by magnetron co-sputtering in this work. The microstructure and resistivity analysis on the films showed that the Cu (0.6 at.% Sn, 2 at.% C) film had better adhesion with the substrate and lower resistivity (2.8 μΩ·cm, after annealing at 600 °C for 1 h). Therefore, the doping of carbon atoms makes less effect to the resistivity by decreasing the amount of the doped large atoms, which results in the decreasing of the whole resistivity of the barrierless structure. After annealing, the doped elements in the film diffused to the interface to form self-passivated amorphous layer, which could further hinder the diffusion between Cu and Si. So thus ternary Cu (0.6 at.% Sn, 2 at.% C) film had better diffusion barrier effect. Co-doping of large atoms and small atoms in the Cu film is a promising way to improve the barrierless structure.

scholarly journals The Synergistic Effects of Alloying on the Performance and Stability of Co3Mo and Co7Mo6 for the Electrocatalytic Hydrogen Evolution Reaction

Hydrogen ◽  
2020 ◽  
Vol 1 (1) ◽  
pp. 11-21
Author(s):  
Youyi Sun ◽  
Alexey Y. Ganin
Keyword(s):  
Hydrogen Evolution ◽  
Synergistic Effects ◽  
Alkaline Media ◽  
Price Of Stability ◽  
X Ray Diffraction ◽  
Free Standing ◽  
X Ray ◽  
Current Decay ◽  
Earth Abundant ◽  
Current Densities

Metal alloys have become a ubiquitous choice as catalysts for electrochemical hydrogen evolution in alkaline media. However, scarce and expensive Pt remains the key electrocatalyst in acidic electrolytes, making the search for earth-abundant and cheaper alternatives important. Herein, we present a facile and efficient synthetic route towards polycrystalline Co3Mo and Co7Mo6 alloys. The single-phased nature of the alloys is confirmed by X-ray diffraction and electron microscopy. When electrochemically tested, they achieve competitively low overpotentials of 115 mV (Co3Mo) and 160 mV (Co7Mo6) at 10 mA cm−2 in 0.5 M H2SO4, and 120 mV (Co3Mo) and 160 mV (Co7Mo6) at 10 mA cm−2 in 1 M KOH. Both alloys outperform Co and Mo metals, which showed significantly higher overpotentials and lower current densities when tested under identical conditions, confirming the synergistic effect of the alloying. However, the low overpotential in Co3Mo comes at the price of stability. It rapidly becomes inactive when tested under applied potential bias. On the other hand, Co7Mo6 retains the current density over time without evidence of current decay. The findings demonstrate that even in free-standing form and without nanostructuring, polycrystalline bimetallic electrocatalysts could challenge the dominance of Pt in acidic media if ways for improving their stability were found.

Microstructure characterization of phase transformations in a Zn–22 wt%Al–2 wt%Cu alloy by XRD, SEM, TEM and FIM

2000 ◽  
Vol 313 (1-2) ◽  
pp. 154-160 ◽  
Author(s):  
Héctor J. Dorantes-Rosales ◽  
Vı́ctor M. López-Hirata ◽  
José L. Méndez-Velázquez ◽  
Maribel L. Saucedo-Muñoz ◽  
David Hernández-Silva
Keyword(s):  
Phase Transformations ◽  
Microstructure Characterization ◽  
Cu Alloy

Systematic characterization of polycrystalline silica–carbonate helices

2016 ◽  
Vol 18 (33) ◽  
pp. 23044-23052 ◽  
Author(s):  
Elias Nakouzi ◽  
Pamela Knoll ◽  
Kenzie B. Hendrix ◽  
Oliver Steinbock
Keyword(s):  
Amorphous Silica ◽  
Barium Carbonate ◽  
Alkaline Media

Biomorphs are complex, life-like structures that emerge from the precipitation of barium carbonate and amorphous silica in alkaline media.

Synthesis and Characterization of Polyaniline Film

2011 ◽  
Vol 239-242 ◽  
pp. 1382-1385
Author(s):  
Na Xu ◽  
Xiao Dong Shen ◽  
Sheng Cui
Keyword(s):  
Ammonium Persulfate ◽  
Pani Film ◽  
Cyclic Voltammograms ◽  
Ultrasonic Dispersion ◽  
Switching Speed ◽  
Color Changes ◽  
Fast Switching ◽  
Ft Ir ◽  
The Relationship

The electrochromic PANI film was prepared by emulsion polymerization with dodecyl benzene sulphonic acid (DBSA) as dopant and ammonium persulfate (APS) as initiator. Ultrasonic dispersion was adopted in the polymerization. The electrochemical properties, the surface morphology and structure of the prepared PANI film was characterized by means of Fourier Transform infrared spectroscopy (FT-IR), cyclic voltammograms (CV) and field emission scanning electron microscope (FE-SEM), respectively. The relationship between the morphology and properties of PANI film was detailedly discussed. The PANI film exhibited an excellent electrochromism with reversible color changes form yellow to purple. The PANI film also had quite good reaction kinetics with fast switching speed, and the response time for oxidation and reduction were 65 ms and 66 ms, respectively.

Fabrication and Characterization of Targets for Shock Propagation and Radiation Burnthrough Measurements on Be-0.9 AT. % Cu Alloy

2004 ◽  
Vol 45 (2) ◽  
pp. 127-136 ◽  
Author(s):  
A. Nobile ◽  
S. C. Dropinski ◽  
J. M. Edwards ◽  
G. Rivera ◽  
R. W. Margevicius ◽  
...  
Keyword(s):  
Shock Propagation ◽  
Cu Alloy ◽  
Fabrication And Characterization

Silver Nanoparticles Supported on Ordered Mesoporous Carbon for Formaldehyde Electrooxidation

2011 ◽  
Vol 110-116 ◽  
pp. 508-513
Author(s):  
Ling Bin Kong ◽  
Ru Tao Wang ◽  
Xiao Wei Wang ◽  
Zhen Sheng Yang ◽  
Yong Chun Luo ◽  
...  
Keyword(s):  
Fuel Cells ◽  
Mesoporous Carbon ◽  
Chemical Reduction ◽  
Chemical Properties ◽  
Ordered Mesoporous Carbon ◽  
Alkaline Solutions ◽  
Cyclic Voltammograms ◽  
Peak Current Density ◽  
Ordered Mesoporous ◽  
Physical And Chemical

Metal nanocatalysts, as the anodic materials, have become increasingly important in fuel cells due to their unique physical and chemical properties. Here we report the ordered mesoporous carbon (CMK-3) supported silver nanocatalysts have been prepared through the wet chemical reduction by using the reduction of formaldehyde. The electrochemical properties of the Ag/CMK-3 nanocatalysts for formaldehyde oxidation are studied by cyclic voltammograms (CV) and chronoamperometric curves (i-t) in alkaline aqueous solutions. The results show that the peak current density (from CV) of the Ag/CMK-3 electrode is 112 mA cm-2, above 2 times higher than that of Ag/XC-72 at the same Ag loading (14.15 μg cm-2). Furthermore, the i-t curves demonstrate that the Ag/CMK-3 nanocatalysts are efficient and stable electrocatalysts for anodic oxidation of formaldehyde in alkaline solutions. Our results indicate that the application potential of Ag/CMK-3 nanocatalysts with the improved electrocatalytic activity has far reaching effects on fuel cells and sensors.

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