Journal articles: 'Cathodic reaction mechanism'

1

ENDO, A. "Cathodic reaction mechanism for dense Sr-doped lanthanum manganite electrodes." Solid State Ionics 86-88 (July 1996): 1191–95. http://dx.doi.org/10.1016/0167-2738(96)00286-x.

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Sunarya, Yayan. "3-Mercaptopropionic Acid as Corrosion Inhibitor for Carbon Steel in CO2 Aerated 1% NaCl Solution with Buffer Control-pH." Molekul 13, no. 2 (December 8, 2018): 98. http://dx.doi.org/10.20884/1.jm.2018.13.2.340.

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In this research, 3-Mercaptopropionic acid (MPA) as corrosion inhibitor of carbon steel in CO2 aerated 1% NaCl solution with buffer pH adjustment has been studied by means of electrochemical impedance (EIS) and polarization (Tafel plot). MPA was found to be an effective carbon steel inhibitor. Percentage inhibition efficiency (IE %) calculated by both Tafel plot and EIS, ranged from 85% to 90%. MPA was found to affect the cathodic processes and act as cathodic-type inhibitors. Mechanism of inhibit corrosion by adsorption mechanism leads to the formation of a protective chemisorbed film on the metal surface film which suppresses the dissolution reaction and the hydrogen evolution reaction is activation controlled.

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Ju, Hong, and Yan Li. "Coulostatic-Based Research on Corrosion Inhibition Mechanism of Three Inhibitors for Hot Dipped Coating Steels." Applied Mechanics and Materials 229-231 (November 2012): 87–90. http://dx.doi.org/10.4028/www.scientific.net/amm.229-231.87.

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The corrosion inhibition mechanism of three inhibitors for hot dipped coating steels in HCl acid was studied by coulostatic method. The results showed that the anodic Tafel slope ba and cathodic Tafel slope bc significantly increased with increasing of corrosion inhibitor concentration. While the corrosion current density Icorr decreases with the corrosion inhibition concentration increasing. And the inhibition efficiency increased with the inhibitor concentration. The inhibiting action of these compounds were attributed to blocking of the electrode surface by adsorption through its active centers. The three inhibitors were both mixed inhibitors, and reacted as good inhibition by the adsorption of the active sites in the cathodic reaction and the anodic reaction of corrosion process.

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Kuzminykh, Maria M., Victoria V. Panteleeva, and Anatoliy B. Shein. "CATHODIC HYDROGEN EVOLUTION ON IRON DISILICIDE. I. ALKALINE SOLUTION." IZVESTIYA VYSSHIKH UCHEBNYKH ZAVEDENIY KHIMIYA KHIMICHESKAYA TEKHNOLOGIYA 62, no. 1 (December 30, 2018): 38–45. http://dx.doi.org/10.6060/ivkkt.20196201.5745.

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The kinetics of hydrogen evolution reaction on FeSi2-electrode in 1.0 M NaOH solution has been studied using methods of polarization and impedance measurements. With the help of diagnostic criteria for the hydrogen evolution reaction mechanisms based on the analysis of the dependence of the parameters of the equivalent electric circuit on overvoltage, it was established that the reaction of hydrogen evolution on iron disilicide in the alkaline electrolyte proceeds along the discharge - electrochemical desorption route, where desorption is the rate-determining stage. Both stages are irreversible, the transfer coefficients of the stages are equal (α1 = α2 = α), simultaneously the hydrogen absorption reaction by the electrode material proceeds in the diffusion mode (in the whole investigated range of potentials). It was found that the adsorption of atomic hydrogen is described by the equation of the Langmuir isotherm. The influence of various methods of modifying of the surface of FeSi2-electrode on the kinetics and mechanism of the cathodic process has been studied. It was found that the modification of the disilicide surface by hydrogenation at a current density of i = 30 mA/cm2, an anodic etching in 0.5 M H2SO4 at the potential E = 0.4 V relative to the standard hydrogen electrode, an anodic etching in 1.0 M NaOH at the potential E = 0.1 V, chemical etching in 5.0 M NaOH at 70 °C reduce the overvoltage of hydrogen evolution, but the mechanism of the cathodic process does not change as a result of the modification. Reduction of the overvoltage of hydrogen evolution on iron disilicide is due to the action of two factors: the development of the surface and the change in the composition of the surface layer of the electrode. It has been concluded that FeSi2 in the alkaline electrolyte is a promising electrode material that exhibits activity in the electrolytic hydrogen evolution reaction.

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Ambrosioni, Brice, Anthony Barthelemy, Dorin Bejan, and Nigel J. Bunce. "Electrochemical reduction of aqueous nitrate ion at tin cathodes." Canadian Journal of Chemistry 92, no. 3 (March 2014): 228–33. http://dx.doi.org/10.1139/cjc-2013-0406.

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The remediation of nitrate-contaminated water using electrochemical reduction at a tin cathode has previously been shown to give almost quantitative denitrification (removal of dissolved nitrogen species) under highly cathodic polarization. A particular focus of this project was to identify specific role(s) for tin in the reaction in the context of the previous literature. The current efficiency for denitrification was enhanced in alkaline solution, and the reaction was accelerated by the presence of small concentrations of Sn(II) salts, which are in a dynamic exchange between cathodic deposition and corrosion of the cathode. Literature precedent indicates that Sn(II) salts promote the “dimerization” pathway of NO to hyponitrite in preference to reduction to ammonia. Hyponitrite is a known intermediate in the electrochemical reduction of nitrate, but its spontaneous decomposition gives predominantly N2O, which does not reduce further to N2. We have shown that hyponitrite is reduced electrochemically in competition with its thermal decomposition, which provides a pathway to N2 via the spontaneous dehydration of HO−NH−NH−OH. The possible role of surface-bound Sn−H species in the reduction mechanism is discussed, but further work is needed to substantiate this proposal.

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Czelej, Kamil, Karol Cwieka, Juan C. Colmenares, and Krzysztof J. Kurzydlowski. "Atomistic insight into the electrode reaction mechanism of the cathode in molten carbonate fuel cells." Journal of Materials Chemistry A 5, no. 26 (2017): 13763–68. http://dx.doi.org/10.1039/c7ta02011b.

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The O-terminated octopolar NiO(111) is predicted to facilitate cathodic transformation of CO₂ to CO₃²⁻ through sequential Mars-van Krevelen and Eley-Rideal mechanisms.

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Kuzminykh, Maria М., Viktoria V. Panteleeva, and Anatoliy B. Shein. "CATHODIC HYDROGEN EVOLUTION ON IRON DISILICIDE. II. ACIDIC SOLUTION." IZVESTIYA VYSSHIKH UCHEBNYKH ZAVEDENII KHIMIYA KHIMICHESKAYA TEKHNOLOGIYA 62, no. 2 (February 7, 2019): 59–64. http://dx.doi.org/10.6060/ivkkt.20196202.5750.

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The kinetics of hydrogen evolution reaction on FeSi2-electrode in 0.5 M H2SO4 solution has been studied using methods of polarization and impedance measurements. With the help of diagnostic criteria for the hydrogen evolution reaction mechanisms based on the analysis of the dependence of the parameters of the equivalent electric circuit on overvoltage, it was established that the reaction of hydrogen evolution on iron disilicide in the sulfuric acid solution proceeds along the discharge - electrochemical desorption route, where desorption is the rate-determining stage. Both stages are irreversible, the transfer coefficients α of the stages are equal, simultaneously the hydrogen absorption reaction by the electrode material proceeds in the kinetic mode (in the whole investigated range of potentials). It was found that the adsorption of atomic hydrogen is described by the equation of the Langmuir isotherm. The influence of thin oxide film on the hydrogen evolution kinetics is noted. The influence of various methods of modifying of the surface of FeSi2-electrode on the kinetics and mechanism of the cathodic process has been studied. It was found that the modification of the disilicide surface by hydrogenation at a current density of i = 30 mA/cm2, an anodic etching in 0.5 M H2SO4 at the potential E = 0.4 V relative to the standard hydrogen electrode, an anodic etching in 1.0 M NaOH at the potential E = 0.1 V, chemical etching in 5.0 M NaOH at 70 °C reduce the overvoltage of hydrogen evolution, but the mechanism of the cathodic process does not change as a result of the electrode modification. Reduction of the overvoltage of hydrogen evolution on iron disilicide is due to the action of two factors: the development of the surface and the change in the composition of the surface layer of the electrode. It has been concluded that FeSi2 in the sulfuric acid solution is a promising electrode material that exhibits activity in the electrolytic hydrogen evolution reaction.

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He, Xiang Zhu, Wen Jun Zhang, and Yong Xiu Wang. "Electrodepositon and Properties of Ni-Diamond Composite Coatings." Advanced Materials Research 702 (May 2013): 176–80. http://dx.doi.org/10.4028/www.scientific.net/amr.702.176.

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Ni-diamond composite coatings are conducted by electrodepositon. The crystal structure and surface morphology of the composite coatings were examined with X-ray diffraction (XRD) and scanning electron microscopy (SEM) and the mechanism of Ni-diamond co-deposition is conducted by catholic polarization and cyclic voltammetry method. The result reveals that diamond particles are successfully embed in Ni matrix and the coatings have an amorphous structure. Cyclic voltammetry indicate that nickel deposition process is an irreversible electrode reaction and cathode polarization curve shift towards positive with the increase of scan rates. Cathodic polarization curve shows that reduction potential of nickel to shift to more negatives with the addition of complexing agent and the slope of the polarization curve is decrease; The addition of brightener and dispersant hinder the deposition of Ni2+ and promote the growth of crystal nucleus; The join of wetting agents and diamond particles have no big influence on the deposition of nickel.

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Perevezentseva, D. O., and E. V. Gorchakov. "Electrochemical Response of Gold Nanoparticles at a Graphite Electrode." Advanced Materials Research 1040 (September 2014): 297–302. http://dx.doi.org/10.4028/www.scientific.net/amr.1040.297.

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The electrochemical activity of gold nanoparticles at graphite electrodes by the method of cyclic voltammetry is studied. In this article the nature of the supporting electrolyte, modification time of graphite electrode by gold nanoparticles and the potential range on the value of the “inverse” cathodic peak are investigated. The “inverse” cathodic peak of gold nanoparticles formed in the reaction mixture HAuCl4:Na3C6H5O7:NaBH4=1:1:4 is observed on the cathodic branch of cyclic voltamperegram at Ec = 0.05 V at graphite electrode. The mechanism of stepwise electrochemical oxidation and reduction of the phase structure of gold on the surface of the graphite electrode in 0.1 M NaOH is offered. The “inverse” cathodic peak of gold nanoparticles on the cathodic branch of cyclic voltammogram at graphite electrode is caused by oxidation of Au2O to Au2O3.<br /><br />

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Garcia-Costa, Alicia L., Andre Savall, Juan A. Zazo, Jose A. Casas, and Karine Groenen Serrano. "On the Role of the Cathode for the Electro-Oxidation of Perfluorooctanoic Acid." Catalysts 10, no. 8 (August 8, 2020): 902. http://dx.doi.org/10.3390/catal10080902.

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Perfluorooctanoic acid (PFOA), C7F15COOH, has been widely employed over the past fifty years, causing an environmental problem because of its dispersion and low biodegradability. Furthermore, the high stability of this molecule, conferred by the high strength of the C-F bond makes it very difficult to remove. In this work, electrochemical techniques are applied for PFOA degradation in order to study the influence of the cathode on defluorination. For this purpose, boron-doped diamond (BDD), Pt, Zr, and stainless steel have been tested as cathodes working with BDD anode at low electrolyte concentration (3.5 mM) to degrade PFOA at 100 mg/L. Among these cathodic materials, Pt improves the defluorination reaction. The electro-degradation of a PFOA molecule starts by a direct exchange of one electron at the anode and then follows a complex mechanism involving reaction with hydroxyl radicals and adsorbed hydrogen on the cathode. It is assumed that Pt acts as an electrocatalyst, enhancing PFOA defluorination by the reduction reaction of perfluorinated carbonyl intermediates on the cathode. The defluorinated intermediates are then more easily oxidized by HO• radicals. Hence, high mineralization (xTOC: 76.1%) and defluorination degrees (xF−: 58.6%) were reached with Pt working at current density j = 7.9 mA/cm2. This BDD-Pt system reaches a higher efficiency in terms of defluorination for a given electrical charge than previous works reported in literature. Influence of the electrolyte composition and initial pH are also explored.

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11

Wang, Shao Qing, Fa Qin Xie, Xiao Fei Yao, and Xiang Qing Wu. "Mechanism of Cathodic Plasma Electrolytic Deposition on Ti6Al4V Alloy in Al(NO₃)₃ Ethanol-Aqueous Solution." Advanced Materials Research 1145 (March 2018): 54–58. http://dx.doi.org/10.4028/www.scientific.net/amr.1145.54.

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Barrier layer was prepared by Micro-arc oxidation(MAO) technique in silicate solution, and cathodic plasma electrolytic deposition (CPED) technique was used to fabricate Al2O3 ceramic coatings on Ti6Al4V alloy in Al(NO3)3(30g/L) and ethanol-aqueous solutions. Surface morphology and elemental of the coatings were investigated by scanning electron microscope (SEM) and energy disperse spectroscopy (EDS). Reaction phenomena were recorded and products of reactions were analyzed by infrared absorption spectrum KBr compression method. Furthermore, mechanisms of different electrolytes were evaluated.

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12

Sakaki, M., and T. Sakakibara. "Excitation, ionization, and reaction mechanism of a reactive cathodic arc deposition of TiN." IEEE Transactions on Plasma Science 22, no. 6 (1994): 1049–54. http://dx.doi.org/10.1109/27.370251.

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13

Asmara, Yuli Panca. "Simulation of CO2 Corrosion of Carbon Steel in High Pressure and High Temperature Environment (HPHT)." Journal of Integrated and Advanced Engineering (JIAE) 2, no. 1 (March 31, 2022): 63–70. http://dx.doi.org/10.51662/jiae.v2i1.41.

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In HPHT environments, the mechanism of CO2 corrosion faces a challenge as an effect of chemical-physical reactions on the metal surface. The presence of other elements in the CO2 system complicates corrosion behavior. To provide a realistic mechanism for corrosion process, some corrosion prediction models have developed software using fundamental theories such as electrochemical reactions and thermodynamics theories. Existing methods to predict corrosion rate models in HPHT environments have shown reasonable results. This paper reviews software of corrosion predictions which calculate corrosion rate based on mechanistic theories that study effects of H2S, acetic acid (HAc) concentrations, shear stress, pH in temperature from 25oC – 100oC and pressure from 1–10 bar. From the simulation, corrosion rate increased significantly in the high pressure CO2 environment. Corrosion rate at pH 4 increased to 30 mm/y at a temperature from 15oC to 90oC. While at pH 8 corrosion rate reached 4 mm/y. This lower corrosion rate indicated a tendency for deposits formation at higher pH. Corrosion rate behaves in a different mechanism at high temperatures. The corrosion rate decreased to 4 mm/y when the temperature increased to more than 90oC. Effects H2S gas and HAc were identified to increase corrosion rate. Both elements provide extra cathodic reaction and create limiting current density in the cathodic reaction process based on polarization sweep models. However, the polarization graph calculated using corrosion models could not display passive behavior in the anodic polarization process. Thus, further, improvement should be considered. From the data calculation, it can be shown that corrosion prediction software can predict corrosion rate in HPHT conditions.

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Miskovic-Stankovic, Vesna. "The mechanism of cathodic electrodeposition of epoxy coatings and the corrosion behaviour of the electrodeposited coatings." Journal of the Serbian Chemical Society 67, no. 5 (2002): 305–24. http://dx.doi.org/10.2298/jsc0205305m.

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The model of organic film growth on a cathode during electrodeposition process proposes the current density-time and film thickness-time relationships and enables the evaluation of the rate contents for the electrochemical reaction of OH? ion evolution and for the chemical reaction of organic film deposition. The dependencies of film thickness and rate constants on the applied voltage, bath temperature and resin concentration in the electrodeposition bath have also been obtained. The deposition parameters have a great effect on the cathodic electrodeposition process and on the protective properties of the obtained electrodeposited coatings. From the time dependencies of the pore resistance, coating capacitance and relative permittivity, obtained from impedance measurements, the effect of applied voltage, bath temperature and resin concentration on the protective properties of electrodeposited coatings has been shown. Using electrochemical impedance spectroscopy, thermogravimetric analysis gravimetric liquid sorption experiments, differential scanning calorimetry and optical miscroscopy, the corrosion stability of epoxy coatings was investigated. A mechanism for the penetration of electrolyte through an organic coating has been suggested and the shape and dimensions of the conducting macropores have been determined. It was shown that conduction through a coating depends only on the conduction through the macropores although the quantity of electrolyte in the micropores of the polymer net is about one order of magnitude greater than that inside the conducting macropores.

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Zhou, JiaYu, Zili Li, JianGuo Liu, Xiao Xing, Gan Cui, ShouXin Zhang, Ran Cheng, and YiShu Wang. "Effect of AC interference on hydrogen evolution reaction of x80 steel." Anti-Corrosion Methods and Materials 67, no. 2 (January 20, 2020): 197–204. http://dx.doi.org/10.1108/acmm-11-2019-2216.

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Purpose The purpose of this paper is to quantify the influence of alternating current (AC) interference on hydrogen evolution reaction of X80 steel. Design/methodology/approach The hydrogen evolution potential was obtained by cathodic potentiodynamic polarization curve. The instantaneous potential under AC interference was obtained by high-frequency acquisition with three-electrode system. Electrochemical impedance spectroscopy and Tafel polarization curves were used to study the influence mechanism of AC interference on instantaneous potential. Findings It was concluded that the hydrogen evolution reaction could occur on X80 steel under AC interference. There were critical AC current densities of about 100 to 200 A/m2, beyond which the cathode reaction of X80 steel changed from oxygen absorption to hydrogen evolution. Besides the pH value, the initial polarization potential EZ and impedance module of the steel/electrolyte interface under AC interference were also the factors that affected the critical AC densities in different solutions. Originality/value This research quantified the hydrogen evolution capacity of X80 steel under AC interference, which could be applied to clear the effect of AC interference on hydrogen evolution reaction.

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Fang, Xiao Jun, Li Liu, Zhi Gang Yang, and Yong Qiang Zhang. "Corrosion Behavior and Mechanism of Oil Casing Steel in CO₂ Salt Solution." Materials Science Forum 1035 (June 22, 2021): 534–38. http://dx.doi.org/10.4028/www.scientific.net/msf.1035.534.

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The influence of temperature, flow rate, PH value, and oxygen content on the corrosion law in the carbon dioxide salt solution of J55 oil casing was investigated by the corrosion weight loss method. The results showed that with the increase of temperature, the corrosion rate of J55 steel first increased and then decreased and the corrosion rate reached the maximum at 100°C. The corrosion rate was closely related to the formation of corrosion products. The increase of the flow rate speeded up the transfer rate of the corrosive medium to the metal surface and hindered the formation of FeCO3 on the metal surface. The corrosion rate was significantly higher than the corrosion rate under static conditions, and as the flow rate increased, the corrosion rate of J55 steel increased accordingly. The increase of the pH value gradually reduced the concentration of hydrogen ions, and cathodic reaction of hydrogen ion depolarization during metal corrosion process was inhibited, and the tendency to form an oxidizing protective film on the surface of carbon steel increased, thereby reducing the corrosion rate of metals. With the increase of oxygen content, there were both hydrogen evolution reaction of CO2 and oxygen absorption reaction caused by O2 in the cathode process. The corrosion rate of J55 steel gradually increased, and at the same oxygen content, the higher the carbon dioxide content, the greater the corrosion rate is.

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17

Endo, A. "Cathodic reaction mechanism of dense La0.6Sr0.4CoO3 and La0.81Sr0.09MnO3 electrodes for solid oxide fuel cells." Solid State Ionics 135, no. 1-4 (November 1, 2000): 353–58. http://dx.doi.org/10.1016/s0167-2738(00)00466-5.

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18

Koizumi, Toshio, Toshio Fuchigami, Zaghloul El-Shahat Kandeel, Norio Sato, and Tsutomu Nonaka. "Reaction Mechanism of Cathodic Crossed Coupling of Acetone with Unsaturated Compounds in Acidic Solution." Bulletin of the Chemical Society of Japan 59, no. 3 (March 1986): 757–62. http://dx.doi.org/10.1246/bcsj.59.757.

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19

Birss, V. I., C. Bock, and H. Elzanowska. "Hydrous Ir oxide films: the mechanism of the anodic prepeak reaction." Canadian Journal of Chemistry 75, no. 11 (November 1, 1997): 1687–93. http://dx.doi.org/10.1139/v97-601.

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The origin and significance of the anodic prepeak (peak A0), seen in cyclic voltammetric studies of hydrous Ir oxide films in acidic solution just prior to the large Ir(III)/(IV) redox peaks (A1/C1), has been examined in this work. By also studying only very thin films, a corresponding cathodic feature (peak C0) has also been identified. The pH dependence of the A0/C0 peaks, assumed to also depict the Ir(III)/(IV) process, has been examined in sulfuric acid solutions, indicating that a ca. −80 mV shift per pH unit applies to this reaction. By also taking into consideration the measured in situ mass changes as the potential is scanned through the A0/C0 peaks, it is shown that these peaks are associated with a greater involvement of anions and more extensive water exchange than is the reaction in the main A1/C1 peaks. Other results also indicate that the film sites that react in the A0/C0 peaks are located deep within the oxide film, likely near the Ir – oxide film interface. Keywords: Ir oxide, hydrous oxide films, cyclic voltammetry, quartz crystal microbalance (QCMB), prepeak, pH dependence, electrochemistry.

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Sarkar, N. K., and J. R. Park. "Mechanism of Improved Corrosion Resistance of Zn-containing Dental Amalgams." Journal of Dental Research 67, no. 10 (October 1988): 1312–15. http://dx.doi.org/10.1177/00220345880670101301.

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The aim of this study was to determine the mechanism of improved corrosion resistance of Zn-containing dental amalgams. Two Zn-containing conventional amalgams, their Zn-free counterparts, and three experimental amalgams (SnHg, ZnHg, and SnZnHg) were evaluated by the potentiodynamic polarization technique in 1% NaCl solution. The main difference between the two types of amalgams was found in their respective breakdown potentials at which passivity was destroyed. The breakdown potential of Zn-containing amalgams was about 200 mV more positive than that of the Zn-free amalgams. The improved stability of the Zn-containing amalgams has been attributed to the formation of a previously reported Zn stannate passive film which, according to the polarization data, is more resistant to the aggressive chloride ion than tin hydroxide that forms on Zn-free amalgams. The formation of Zn stannate was not found to affect the oxygen reduction reaction, the major cathodic reaction involved in the corrosion of dental amalgams.

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Lang, Kamil, Jiří Vondrák, and Dana M. Wagnerová. "Interaction of Mn(III)Tetraphenylporphyrin with Superoxide; The Reaction Mechanism and Evidence for a Peroxo Complex." Collection of Czechoslovak Chemical Communications 59, no. 5 (1994): 1059–65. http://dx.doi.org/10.1135/cccc19941059.

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Cathodic one-electron reduction of Mn(III)TPP and O2 in an aprotic solvent yields Mn(II)TPP and the superoxide anion radical O2-. The Mn(II)TPP and O2- react in solution to the side-on peroxo complex Mn(III)TPP-O22-, which is oxidized at the electrode at a peak potential of Epa = 0.40 V vs NHE (k ≈ 104 dm3 mol-1 s-1). The rate-determining step of the overall two-electron oxidation is the transfer of the first electron coupled with a structure rearrangement of the peroxo complex to a superoxo complex.

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Kahyarian, Aria, and Srdjan Nesic. "H2S corrosion of mild steel: A quantitative analysis of the mechanism of the cathodic reaction." Electrochimica Acta 297 (February 2019): 676–84. http://dx.doi.org/10.1016/j.electacta.2018.12.029.

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Han, Yu Mei, and X. Grant Chen. "Corrosion Characteristics of Al-B₄C Metal Matrix Composites in Boric Acid Solution." Materials Science Forum 877 (November 2016): 530–36. http://dx.doi.org/10.4028/www.scientific.net/msf.877.530.

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The corrosion behavior of Al-B4C metal matrix composites in H3BO3 solutions with different Cl- contents was investigated using potentiodynamic polarization and zero resistance ammetry techniques. Results show that the corrosion of Al-B4C composites in H3BO3 solution increases with increasing B4C volume fraction in the composites. The main corrosion characteristic of Al-B4C composites in H3BO3 solution is the galvanic corrosion between Al matrix and B4C particles. In the galvanic couple, B4C particle acts as cathode and Al matrix acts as anode. The cathodic reaction is hydrogen revolution reaction, which controls the corrosion mechanism of Al-B4C composites. Pitting is not observed on the composite surface in the H3BO3 solution with zero Cl-. However, with addition of Cl- in H3BO3 solution, pitting occurs and the corrosion resistance remarkably decreases with increasing Cl- content. The corrosion resistance of Al-B4C composites in H3BO3 solutions is compared with that in the standard 3.5% NaCl solution.

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Sdanghi, G., L. Yefsah, F. Mauvy, E. Djurado, T. David, J.-M. Bassat, and J. Laurencin. "Reaction Mechanisms of La₂NiO_4+δ Oxygen Electrodes Operated in Electrolysis and Fuel Cell Mode." Journal of The Electrochemical Society 169, no. 3 (March 1, 2022): 034518. http://dx.doi.org/10.1149/1945-7111/ac58c3.

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The reaction mechanisms governing the electrochemical behavior of La2NiO4+δ (LNO) oxygen electrodes for Solid Oxide Cells have been investigated through a coupled experimental and modeling approach. In this frame, a set of experiments was performed on a symmetrical cell using a three-electrode setup. A micro-scale electrode model considering two reaction pathways, i.e. bulk and surface paths, has been developed to describe the experimental results. The microstructural parameters of the electrode were obtained by FIB-SEM tomography. The model was calibrated using the experimental polarization curves measured at different temperatures, and it was validated using electrochemical impedance diagrams recorded at open circuit potential (OCP) and under polarization for different oxygen partial pressures. It has been evidenced that the LNO reaction mechanism depends on both the temperature and the polarization. At OCP, the reaction mechanism is controlled by the bulk path at 650 °C and by the surface path at higher temperatures. A transition from the bulk path towards the surface path was observed under cathodic polarizations. These results have been interpreted by considering the evolution of the LNO over stoichiometry with the electrode polarization. The evolution of the electrode polarization resistance with the oxygen partial pressure has been also investigated.

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McEvoy, Todd M., and Keith J. Stevenson. "Elucidation of the electrodeposition mechanism of molybdenum oxide from iso- and peroxo-polymolybdate solutions." Journal of Materials Research 19, no. 2 (February 2004): 429–38. http://dx.doi.org/10.1557/jmr.2004.19.2.429.

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The cathodic electrodeposition of molybdenum oxide thin films prepared from aqueous solutions containing iso-polymolybdates and peroxo-polymolybdates is described. Chronocoulometry, x-ray photoelectron spectroscopy, spectroelectrochemistry, and electrochemical quartz crystal microgravimetry were used to establish corresponding reaction mechanisms for films grown at different deposition potentials. Electrodeposition from acidified iso-polymolybdate solutions proceeds by the reduction of molybdic acid, whereas deposition from aqueous peroxo-based solutions involves the graded reduction of several solution components, primarily comprising molybdic acid and peroxo-polymolybdates. Careful regulation of the deposition potential allows for controlled growth of distinct molybdenum oxide compositions producing films with varied water content and valency.

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Sainis, Salil, and Caterina Zanella. "A Study of the Localized Ceria Coating Deposition on Fe-Rich Intermetallics in an AlSiFe Cast Alloy." Materials 14, no. 11 (June 3, 2021): 3058. http://dx.doi.org/10.3390/ma14113058.

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Corrosion inhibiting conversion coating formation is triggered by the activity of micro-galvanic couples in the microstructure and subsequent local increase in pH at cathodic sites, which in the case of aluminium alloys are usually intermetallics. Ceria coatings are formed spontaneously upon immersion of aluminium alloys in a cerium conversion coating solution, the high pH gradient in the vicinity of intermetallics drives the local precipitation of ceria conversion compounds. Cu-rich intermetallics demonstrate a highly cathodic nature and have shown the local precipitation reaction to occur readily. Fe-rich intermetallics are, however, weaker cathodes and have shown varied extents of localized deposits and are in focus in the current work. Model cast Al-7wt.%Si alloys have been designed with 1 wt.% Fe, solidified at different cooling rates to achieve two different microstructures, with big and small intermetallics, respectively. Upon subjecting the two microstructures to the same conversion coating treatment (immersion in a 0.1 M CeCl3 solution) for a short period of 2 h, preferential heavy deposition on the boundaries of the big intermetallics and light deposition on the small intermetallics was observed. Based on these observations, a mechanism of localized coating initiation at these Fe-rich intermetallic particles (IM) is proposed.

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Kahyarian, Aria, Bruce Brown, and Srdjan Nešić. "The Unified Mechanism of Corrosion in Aqueous Weak Acids Solutions: A Review of the Recent Developments in Mechanistic Understandings of Mild Steel Corrosion in the Presence of Carboxylic Acids, Carbon Dioxide, and Hydrogen Sulfide." Corrosion 76, no. 3 (January 20, 2020): 268–78. http://dx.doi.org/10.5006/3474.

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The recent developments in mechanistic understandings of mild steel corrosion in the presence of carboxylic acids, carbon dioxide, and hydrogen sulfide, when place side by side, reveal a simple, universal mechanism despite all the differences conventionally presumed for these corroding systems. These findings are recast into a generic mechanistic view of corrosion in aqueous weak acid solutions herein. In this mechanism, the buffering effect resulting from the chemical dissociation reaction inside the boundary layer, is highlighted as an inherent property of all weak acids. The validity of this mechanism was further examined through mathematical experimentation based on a comprehensive mechanistic model. It is shown that this mechanism is able to account for a wide range of characteristic behavior of cathodic currents, including those previously associated with the direct reduction reactions. The results are ultimately presented as a simple and generic categorization of weak acids based on their pKa values to serve as a basis to assess the detrimental effect of any weak acid on mild steel corrosion in aqueous acidic solutions.

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Zhao, Di, Jiali Fu, Yan Liu, Fenghua Guo, and Aichang Li. "Photoelectrocatalytic activity and reaction mechanism of Ag2S/Ag3PO4/Ni nanothin films for rhodamine B." Functional Materials Letters 10, no. 02 (April 2017): 1750005. http://dx.doi.org/10.1142/s1793604717500059.

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Ag2S/Ag3PO4/Ni thin films were prepared using an electrochemical method. The surface morphology, phase structure, optical characteristics and band structure of the thin films were analyzed using scanning electron microscopy (SEM), X-ray diffraction (XRD) and ultraviolet-visible diffuse reflectance spectroscopy (UV–Vis DRS), respectively. Additionally, the films photoelectrocatalytic (PEC) activity and stability were evaluated using rhodamine B (RhB) as a model compound. Ag2S/Ag3PO4/Ni thin films that were prepared under optimum conditions contained nanoparticles that were approximately 25[Formula: see text]nm in size and exhibited high PEC activity. At an optimum cathodic bias of [Formula: see text]0.60[Formula: see text]V, the PEC degradation rate of RhB was 1.93 times greater than that of Ag3PO4/Ni thin film. Especially, the film displayed excellent PEC stability, even after being reused eight times. The possible PEC reactions between the film and RhB under visible-light irradiation are discussed in this paper.

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Liu, Pingli, Yanhua Zhu, and Liqiang Zhao. "New corrosion inhibitor for 13Cr stainless steel in 20% HCl solution." Anti-Corrosion Methods and Materials 67, no. 6 (September 23, 2020): 557–64. http://dx.doi.org/10.1108/acmm-12-2019-2228.

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Purpose A novel compound was synthesized by cyclohexylamine, acetophenone and cinnamaldehyde through Mannich reaction in laboratory to use as corrosion inhibitor for steel in acidification process. Design/methodology/approach The corrosion and inhibition of 13Cr stainless steel in conventional acidification solution were investigated by electrochemical measurements and soaking experiments. The corrosion appearance was observed with scanning electron microscope on the whole surface of 13Cr stainless steel in 20% HCl solution, and the protection film was confirmed on the surface in presence with inhibitor. Findings Results manifested that the inhibitor C23H27NO can effectively inhibit the corrosion reaction by forming an adsorption layer function as a barrier. Polarization curves indicated that the mixed inhibitor can reduce anodic dissolution and cathodic hydrogen evolution reactions simultaneously. The results of impedance measurements indicated that this inhibitor cannot change the corrosion mechanism of 13Cr stainless steel in 20% HCl solution. The results of the study can provide a theoretical basis for the application of 13Cr stainless steel in conventional acidification solutions during oil well acidification construction process. Originality/value A novel compound was synthesized by cyclohexylamine, acetophenone and cinnamaldehyde through Mannich reaction in laboratory to use as corrosion inhibitor for steel in acidification process. The corrosion and anti-corrosion mechanism of 13Cr steel in acid solution was proposed.

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García, M. A., F. Ginez, and S. A. Gamboa. "Oxygen Reduction Reaction on Pt-ZrO2/C during the Alcohol Crossover in Experimental Direct Alcohol Fuel Cells." Journal of New Materials for Electrochemical Systems 21, no. 1 (April 18, 2018): 057–62. http://dx.doi.org/10.14447/jnmes.v21i1.524.

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Pt–ZrO2/C composite was synthesized by chemical reduction process. ZrO2 precursor was obtained by sol-gel at room temperature. The synthesis allowed the formation of Pt-ZrO2/C nanoparticles. The nanoparticles were characterized by X-ray diffraction (XRD), Brunauer-Emmett-Teller (BET) and transmission electron microscopy (TEM) techniques. The electrochemical experiments were carried out for investigating the electro-catalytic properties of the synthesized composite to promote the cathodic reaction in direct alcohol fuel cells (DAFC). The results indicated that Pt-ZrO2/C showed more tolerance than Pt/C based electrocatalyst to the presence of methanol or ethanol (due to alcohol crossover) during the oxygen reduction reaction (ORR) in direct alcohol fuel cells. The experimental results indicated that the ORR on Pt-ZrO2/C composite was predominant by the four electron transfer mechanism and first order reaction. The Pt-ZrO2/C based electrocatalyst showed adequate performance to carry out the ORR in experimental direct alcohol fuel cells operating at room temperature. The results revealed that Pt-ZrO2/C composite could be considered as a suitable candidate for reducing oxygen on the cathode of experimental DAFCs.

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Takenaka, T., H. Okada, R. Shimokawa, and T. Morishige. "Influence of bath composition on Ti metal deposition in molten CaCl2 containing calcium titanate." MATEC Web of Conferences 321 (2020): 07010. http://dx.doi.org/10.1051/matecconf/202032107010.

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The dependence of the cathodic behavior of a Ti ion on the molar ratio of CaO to TiO2 (RCaO/TiO2) was investigated in molten CaCl2 above 1373 K, and the influence of RCaO/TiO2 on Ti metal deposition was discussed. The reduction mechanism changed at RCaO/TiO2 = 1.5; a three-step reduction of Ti was suggested in the melt of RCaO/TiO2 < 1.5, while a two-step reduction seemed to occur above RCaO/TiO2 = 1.5. Titanium metal deposition was also affected by RCaO/TiO2 as well as by the cathode potential, and the suitable RCaO/TiO2 was likely 1.5. Since this value was the same as the suitable value in the molten fluoride system, Ti metal was thought to be obtained only from Ti2O76-. Silicon and Al metal were obtained electrochemically in molten CaCl2 containing calcium silicate and aluminate more easily than Ti metal. The difficulty of the Ti metal deposition is likely to be caused by the so-called shuttle reaction; the shuttle reaction can occur in the Ti metal electrolysis because some ionic states of Ti are stable in the bath. To realize better Ti metal deposition, the control of the shuttle reaction should be important.

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Liu, Yi-Li, Yuan-Cheng Zhu, Ling-Bo Qu, Ran Yang, Xiao-Dong Yu, and Wei-Wei Zhao. "Unique Redox Reaction between CuO Photocathode and Cysteine: Insight into the Mechanism for Cathodic Photoelectrochemical Bioanalysis." ACS Applied Bio Materials 2, no. 7 (June 17, 2019): 2703–7. http://dx.doi.org/10.1021/acsabm.9b00428.

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Ruvinskiy, Pavel S., Antoine Bonnefont, Cuong Pham-Huu, and Elena R. Savinova. "Using Ordered Carbon Nanomaterials for Shedding Light on the Mechanism of the Cathodic Oxygen Reduction Reaction." Langmuir 27, no. 14 (July 19, 2011): 9018–27. http://dx.doi.org/10.1021/la2006343.

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Stankovic, Zvonimir, Vladimir Cvetkovski, and Vesna Grekulovic. "The effect of bi presence as impurities in anodic copper on kinetics and mechanism of anodic dissolution and cathodic deposition of copper." Chemical Industry 64, no. 4 (2010): 337–42. http://dx.doi.org/10.2298/hemind100329021s.

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The influence of Bi, as foreign metal atoms in anode copper, on kinetics and mechanism of anodic dissolution and cathodic deposition of copper in acidic sulfate solution was investigated using the galvanostatic single-pulse method. Results indicate that presence of Bi atoms in anode copper increases the exchange current density, as determined from the Tafel analysis of the electrode reaction, which is attributed to the increase of the crystal lattice parameter determined from XRD analysis of the electrode material.

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Wu, Donghai, Yuexian Li, Guanghua Lu, Qiuhong Lin, Lei Wei, and Pei Zhang. "Removal of Aqueous Para-Aminobenzoic Acid Using a Compartmental Electro-Peroxone Process." Water 13, no. 21 (October 20, 2021): 2961. http://dx.doi.org/10.3390/w13212961.

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The presence of emerging contaminant para-aminobenzoic acid (PABA) in the aquatic environment or drinking water has the potential to harm the aquatic ecosystem and human health. In this work, the removal of aqueous PABA by a compartmental electro-peroxone (E-peroxone) process was systematically investigated from the kinetic and mechanism viewpoints. The results suggest that single electrolysis or ozonation was inefficient in PABA elimination, and the combined E-peroxone yielded synergistic target pollutant degradation. Compared to the conventional E-peroxone oxidation, the sequential cathodic reactions, followed by anodic oxidations, improved the PABA removal efficiency from ~63.6% to ~89.5% at a 10-min treatment, and the corresponding pseudo first-order kinetic reaction rate constant increased from ~1.6 × 10−3 to ~3.6 × 10−3 s−1. Moreover, the response surface methodology (RSM) analysis indicated that the appropriate increase of inlet ozone concentration, applied current density, initial solution pH value, and solution temperature could accelerate the PABA degradation, while the excess of these operational parameters would have a negative effect on the treatment efficiency. The comparation tests revealed that the coupling of electrolysis and ozonation could synergistically produce hydroxyl radicals (HO•) and the separation of cathodic reactions and anodic oxidations further promoted the HO• generation, which was responsible for the enhancement of PABA elimination in the compartmental E-peroxone process. These observations imply that the compartmental E-peroxone process has the potential for aqueous micropollutants elimination, and the reaction conditions that favor the reactive oxygen species generation are critical for the treatment efficiency.

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Stankovic, Z. D., V. Cvetkovski, and M. Vukovic. "The effect of antimony presence in anodic copper on kinetics and mechanism of anodic dissolution and cathodic deposition of copper." Journal of Mining and Metallurgy, Section B: Metallurgy 44, no. 1 (2008): 107–14. http://dx.doi.org/10.2298/jmmb0801107s.

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The influence of the presence of Sb atoms, as foreign metal atoms in anode copper, on kinetics, and, on the mechanism of anodic dissolution and cathodic deposition of copper in acidic sulfate solution has been investigated. The galvanostatic single-pulse method has been used. Results indicate that presence of Sb atoms in anode copper increase the exchange current density as determined from the Tafel analysis of the electrode reaction. It is attributed to the increase of the crystal lattice parameter determined from XRD analysis of the electrode material.

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Arukalam, I. O. "Inhibiting potential of hydroxypropyl methylcellulose on acid corrosion of mild steel and aluminium." Pigment & Resin Technology 43, no. 6 (November 3, 2014): 394–404. http://dx.doi.org/10.1108/prt-07-2013-0059.

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Purpose The aim of this paper is to appraise the inhibiting potential of hydroxypropyl methylcellulose (HPMC) on the corrosion of mild steel and aluminium in sulphuric and hydrochloric acid solutions. Design/methodology/approach The effects of two different corrodents on the dissolution of mild steel and aluminium were examined. Corrosion rates were determined using the weight loss technique. Inhibition efficiency was estimated by comparing the corrosion rates in absence and presence of the additive. The kinetics and mechanism of HPMC adsorption were investigated by impedance study while the anodic and cathodic partial reactions were studied by polarization measurements. Findings The results reveal that corrosion rate of mild steel and aluminium decreased with addition of HPMC. The corrosion rate and inhibition efficiency were found to depend on the concentration of the inhibitor. The polarization data indicated that the inhibitor was of mixed-type, with predominant effect on the cathodic partial reaction. electrochemical impedance spectroscopy confirms that corrosion inhibition was by adsorption on the metal surface following Freundlich adsorption isotherm via physisorption mechanism. Originality/value Hydroxypropyl methylcellulose has been studied for the first time as an inhibitor of mild steel and aluminium corrosion and the results suggest that the inhibitor could find practical applications in corrosion control in HCl and H2SO4 acid media. The findings are particularly useful, considering the fact that HPMC is a good film former and viscosity enhancer which could also be used in paint formulation.

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Oguzie, E. E. "Adsorption and corrosion inhibitive properties of Azadirachta indica in acid solutions." Pigment & Resin Technology 35, no. 6 (November 1, 2006): 334–40. http://dx.doi.org/10.1108/03699420610711335.

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PurposeTo assess the protective effect and adsorption behaviour of Azadirachta indica extract in controlling mild steel corrosion in 1 M H2SO4 and 2 M HCl.Design/methodology/approachThe inhibitive effect of the plant extract was monitored using the gas‐volumetric technique. The inhibition mechanism was inferred by curve fitting of the experimental data to known adsorption isotherms and the trend of inhibition efficiency with temperature.FindingsAzadirachta indica extract effectively inhibited steel corrosion in the acid media studied by virtue of adsorption. The inhibitor adsorption characteristics were approximated by Langmuir isotherm. The extract functioned as a mixed inhibitor, depending on its concentration. The prime effect at lower concentration was mitigation of the cathodic reaction by physical adsorption of protonated species in the extract and at higher concentration the anodic reaction was inhibited by chemisorption of molecular species.Originality/valueThis paper provides novel information on the effectiveness of Azadirachta indica extract as a green corrosion inhibitor for steel in highly acidic environments as well as possible mechanisms of the inhibitive action.

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Altunöz-Erdoğan, Deniz, Nevin Erk, and Esma Kılıç. "Voltammetric methods of reboxetine analysis and the mechanism of its electrode reactions." Open Chemistry 11, no. 5 (May 1, 2013): 706–16. http://dx.doi.org/10.2478/s11532-013-0213-8.

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AbstractReboxetine (RBX) electrochemical redox behavior at hanging mercury drop (HMDE) and glassy carbon electrodes (GCE) was studied in various pH Britton-Robinson universal buffers using cyclic voltammetry and square-wave voltammetry. RBX was reduced at the HMDE and oxidized at the GCE with reversible adsorption controlled and irreversible diffusion controlled processes respectively. The anodic peak is due to the amine and the cathodic peak may correspond to oxygen protonation. An oxidation reaction mechanism is proposed. The linear relation between peak currents and RBX concentration allowed simple, sensitive, precise and inexpensive voltammetric procedures to be developed. The limit of detection was 0.04 µM RBX. The procedures were successfully applied to human urine and RBX tablet assay. Therapeutic RBX concentrations in human serum were not detected due to strong drug-protein binding. Using bovine serum albumin, the methods were used to investigate the effect of serum protein binding on RBX determination.

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Aghababaie, Eiman, Hamid Reza Javadinejad, Mohsen Saboktakin Rizi, and Marzieh Ebrahimian. "Effect of Chlorine Ion on the Corrosion of 316L Austenitic Stainless Steel." Advanced Engineering Forum 23 (July 2017): 1–12. http://dx.doi.org/10.4028/www.scientific.net/aef.23.1.

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In this study corrosion resistance of 316L stainless steel has been investigated in a solution containing different percentages of hypochloric solution. In order to examine the rate and mechanism of the occurrence of pitting corrosion in this steel, various corrosion tests have been used. In addition, the locale of the pitting corrosion has been examined by scanning electron microscope. Results show that the presence of chlorine ion with the increase of cathodic reaction rates cause to increase the likelihood of pitting corrosion in 316L steel.

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Nielsen, Merete Folmer, Belen Batanero, Thorsten Löhl, Hans J. Schäfer, Ernst-Ulrich Würthwein, and Roland Fröhlich. "Enantioselective Cathodic Reduction of 4-Methylcoumarin: Dependence of Selectivity on Reaction Conditions and Investigation of the Mechanism." Chemistry - A European Journal 3, no. 12 (December 1997): 2011–24. http://dx.doi.org/10.1002/chem.19970031216.

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Guo, Wei Ling, En Zhong Li, and Hai Dou Wang. "Study on MnO₂ Nanomaterials Catalyze Electrogenerated Chemiluminescence of Ru(bpy)₃²⁺." Advanced Materials Research 662 (February 2013): 68–71. http://dx.doi.org/10.4028/www.scientific.net/amr.662.68.

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MnO2 nano-materials can remarkably catalyze the electrochemical reduction reaction of O2, so MnO2 nano-materials can be used as catalysts for electrogenerated chemiluminescence (ECL) of Ru(bpy)32+ in this paper. As a result, a novel cathodic ECL of Ru(bpy)32+ at positive potential of +0.4 V (vs. Ag/AgCl) was triggered by reactive oxygen species (HO2•- or OH•-) on an in situ electrodeposited MnO2 nano-structured electrode. Finally, catalytic mechanism of MnO2 nano-materials is deduced and provides a theoretical basis for preparing novel ECL Sensor with high sensitivity.

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Sooriyalakshmi*, N., and Dr Jane Helena. H. "Rebar Corrosion Monitoring and Prevention Techniques." International Journal of Engineering and Advanced Technology 10, no. 3 (February 28, 2021): 219–22. http://dx.doi.org/10.35940/ijeat.f8782.0210321.

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Corrosion is the gradual degradation of the metal by chemical reaction with the environment. The service life of the structure is a major concern that depends on the cost involved in construction, maintenance, and repair works. This paper discusses the corrosion mechanism, factors influencing corrosion, corrosion monitoring techniques, and corrosion protection methods. The monitoring techniques include the Linear polarization method, Active monitoring using sensors, DAQ cards, impedance measurement using chips, etc. Prevention methods include an application of paints with various chemical compositions, cathodic protection inhibitors, the use of fiberreinforced polymer, etc.

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Qiu, Na, Chanchan Shen, Yongxia Liu, Xiuqing Li, Guangyin Jia, Jingping Qin, and Xinglei Wang. "Degradation of Ibuprofen by the Electro/Fe3+/Peroxydisulfate Process: Reactive Kinetics, Degradation Products and Mechanism." Catalysts 12, no. 3 (March 13, 2022): 329. http://dx.doi.org/10.3390/catal12030329.

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Ibuprofen (IBU), a nonsteroidal anti-inflammatory drug, is one of the most widely used and frequently detected pharmaceuticals and personal care products in water bodies. This study examined the IBU degradation in aquatic solutions via ferric ion activated peroxydisulfate (PDS) coupled with electro-oxidation (EC/Fe3+/PDS). The degradation mechanisms involved three synergistic reactions in the EC/Fe3+/PDS system, including: (1) the electro-oxidation; (2) SO4•− generated from the activation of PDS by ferrous ions formed via cathodic reduction; (3) SO4•− generated from the electron transfer reaction. The radical scavenging experiments indicated that SO4•− and •OH dominated the oxidation process. The effects of the applied current density, PDS concentration, Fe3+ dosage, initial IBU concentration and initial pH as well as inorganic anions and humic acid on the degradation efficiency, were studied, and the degradation process of IBU followed the pseudo-first-order kinetic model. About 99.37% of IBU was removed in 60 min ((Fe3+ concentration) = 2.0 mM, (PDS concentration) = 12 mM, (initial IBU concentration) = 30 mg/L, current density = 15 mA/cm2, initial pH = 3). Finally, seven intermediate compounds were identified and probable IBU degradation pathways in the EC/Fe3+/PDS system were speculated.

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Crolet, J. L. "Detailed mechanisms of hydrogen charging and hydrogen stress cracking of steel in liquid ammonia storage." Matériaux & Techniques 107, no. 4 (2019): 401. http://dx.doi.org/10.1051/mattech/2019022.

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When the unprecedented environmental cracking of steel in liquid ammonia was collectively studied, its undisputable “anodic character” was taken as the signature of a stress corrosion cracking mechanism, which is effectively the case in aqueous corrosion. Conversely, when the metallurgical precautions proved to be the same as in sour service, this strongly suggested a hydrogen stress cracking mechanism. In aqueous corrosion, however, this can only occur by cathodic hydrogen charging at low potential, and for 50 years, this basic contradiction could never be overcome. Actually, it occurs that the liquid ammonia solvent (NH3) is 50% richer in hydrogen than the water solvent (OH2), so that hydrogen gas can also be produced by a partial oxidisation into ½ N2 + H2. This therefore induces a theoretical possibility of an “anodic” hydrogen charging, or more exactly a protonic cathodic reaction only running at high potential on passive iron in oxygen contaminated ammonia. And once the detrimental potential is achieved through appropriate combinations of oxygen and water traces, the charging process becomes an autonomous oxidation-reduction at the steel surface NH3 → ½ N2 + H2 + (H+ + e−)steel. In Part II (Jean-Louis Crolet, Matériaux & Techniques 107, 402, 2019), this new assumption will be successfully confronted to all the factual data from both field and laboratory experience.

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TSUJI, Yoichiro, Koji AMEZAWA, Takayuki NAKAO, Toshiaki INA, Tatsuya KAWADA, Kentaro YAMAMOTO, Yoshiharu UCHIMOTO, and Yuki ORIKASA. "Investigation of Cathodic Reaction Mechanism in Solid Oxide Fuel Cells by Operando X-Ray Absorption Spectroscopy." Electrochemistry 88, no. 6 (November 5, 2020): 560–65. http://dx.doi.org/10.5796/electrochemistry.20-00108.

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Mabrouk, El-Sayed M., Hamada M. Killa, Abdel Fattah A. Abdel Fattah, and Shalaby A. Yasen. "Polarographic and Cyclic Voltammetric Behaviour of Some Azo Compounds Derived from Sulfonamide in DMF-Aqueous Solutions." Collection of Czechoslovak Chemical Communications 57, no. 2 (1992): 268–75. http://dx.doi.org/10.1135/cccc19920268.

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The polarographic and cyclic voltammetric behaviour of (2-hydroxyphenylazo)-4-benzenesulfonamide and some of its derivatives have been studied in Britton-Robinson buffer series containing 30 vol.% of DMF. Over the entire pH range (2-12), the reduction pathway occurs through an irreversible 4-electron step corresponding to the reduction of N=N center to the amine stage. The voltammograms recorded in acidic and alkaline solution at different scan rates exhibit one or two cathodic peaks depending on the substituent and the pH of the medium. The electrode reaction mechanism was suggested, also the kinetic parameters were calculated.

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Kichigin, Vladimir I. "On the extrema on the potential dependence of the charge transfer resistance in the hydrogen evolution reaction." Вестник Пермского университета. Серия «Химия» = Bulletin of Perm University. CHEMISTRY 11, no. 2 (2021): 154–64. http://dx.doi.org/10.17072/223-1838-2021-2-154-164.

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The shape of the charge transfer resistance Rct versus overpotentialh curves for the hydrogen evolution reaction (Volmer – Heyrovsky mechanism, Langmuir isotherm for adsorbed hydrogen) was analyzed. It was shown that, depending on the kinetic parameters of reaction steps, three cases are possible: (i) there are no extrema on these curves; (ii) there is one maximum; (iii) there are a minimum and a maximum. Some ways for obtaining kinetic parameters from the curves with extrema are discussed. It was shown that the rate constants and transfer coefficients of all steps can be determined from logRct–h curve alone if there are a minimum and maximum of Rct in cathodic region. In the absence of the extrema, the amount of kinetic information gained from logRct–h plots is considerably reduced.

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Öztürk, Funda, Zehra Durmuş, Öznur Ölmez Uçkan, Emine Kiliç, and Esma Kiliç. "Synthesis and electroreduction of 2-[(8-hydroxyquinoline-5-yl)azo]benzo[c]cinnoline in DMSO–H2O (1:1) medium." Collection of Czechoslovak Chemical Communications 75, no. 11 (2010): 1201–16. http://dx.doi.org/10.1135/cccc2010072.

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2-[(8-Hydroxyquinoline-5-yl)azo]benzo[c]cinnoline (HQAB) was prepared and characterized by elemental analysis, MS, FTIR and 1H NMR techniques. The electrochemical reduction of HQAB has been investigated by cyclic voltammetry, chronoamperometry and controlled potential electrolysis at mercury pool electrode in the pH range 3.5–9.4. The number of electrons transferred in the electrode reaction, diffusion coefficients and standart rate constants were calculated. In acidic medium, cyclic voltammograms display four cathodic peaks, with the total exchange of 6 e– and 6 H+. By contrast, the reverse scan displays two anodic peaks. Constant potential electrolysis at –1.0 V and TLC analysis of the product reveals that the reduction of azo group (in the bridge) in HQAB does not stop at the hydrazo stage but goes further through the cleavage of –NH–NH– linkage to give amino compounds as the final products. The voltammograms recorded in basic medium exhibit two cathodic peaks corresponding to 4 e–, 4 H+ and two reverse anodic peaks, and thus the reduction stopped at hydrazo stage. A tentative mechanism for the reduction has been suggested.

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Li, Zili, Chao Yang, Gan Cui, Shouxin Zhang, and Chengbin Zhang. "Effect of pH and NaCl concentration on the hydrogen evolution reaction of X60 steel." Anti-Corrosion Methods and Materials 66, no. 2 (February 21, 2019): 203–9. http://dx.doi.org/10.1108/acmm-08-2018-1978.

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Purpose When hydrogen evolution reaction occurs on a metal surface, on the one hand, the generated hydrogen atom may penetrate into the metal that causes the hydrogen embrittlement failure of materials; on the other hand, the hydrogen generation may increase the local pressure in the coating and cause coating blistering. The purpose of this study is to study the effect of NaCl concentration and pH on hydrogen evolution reaction of X60 steel. Design/methodology/approach A cathodic polarization curve 257E-2V vs OCP and EIS was obtained by conventional three-electrode system in different NaCl concentrations, 257E3.5 and pH. Second, various parameters such as hydrogen evolution, over-potential current–density polarization resistance and capacitance of double electric layer were obtained based on fitting of the experimental data. Finally, the reaction mechanism was determined by Tafel curves. Findings It was concluded that in different NaCl concentrations, diffusion layer induced by concentration polarization affects the diffusion process of H+ ions, which makes over-potential increase. Under great effect of concentration polarization, the reaction is different in acid and alkaline environments, and the dielectric layer shows the characteristic of meta-alkaline adsorption, which makes difference in mechanism. Originality/value This research not only has theoretical significance but also gains utilization prospect. Ultimately, this research could be applied to clear hydrogen evolution process and protect long-distance pipeline against delamination.

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Journal articles on the topic 'Cathodic reaction mechanism'

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