scholarly journals Analysis of quasi-reversible cyclic voltammograms: Transformation to scan-rate independent form

2018 ◽  
Vol 90 ◽  
pp. 69-72 ◽  
Author(s):  
Tamás Pajkossy
Keyword(s):  
Cyclic Voltammograms ◽  
Independent Form ◽  
Scan Rate

scholarly journals Formic Acid and Methanol Oxidation for Pt/C Catalyst Depending on Rotating Speed, Scan Rate and Concentration

2019 ◽  
Vol 1 (2) ◽  
pp. 1-4
Author(s):  
Ayşe Bayrakçeken Yurtcan
Keyword(s):  
Sulfuric Acid ◽  
Formic Acid ◽  
Methanol Oxidation ◽  
Rotating Disk ◽  
Rotating Disk Electrode ◽  
Cyclic Voltammograms ◽  
Oxidation Activity ◽  
Operational Conditions ◽  
Rotating Speed ◽  
Scan Rate

The oxidation of small organic molecules on the catalyst under electrocatalytic conditions is important for the operation of liquid feed fuel cells. The basic reaction mechanisms toward the oxidation of methanol and formic acid continue to be a matter of debate under real operational conditions of electrochemical systems. The electrocatalytic activity of the commercial Pt/C catalyst was investigated in sulfuric acid/methanol and sulfuric acid/formic acid mixtures using electrochemical measurements. This work presents the variation of formic acid and methanol oxidation on the catalyst depending on hydrodynamic conditions using the rotating disk electrode. Cyclic voltammograms were obtained at different scan rates, rotating speeds and concentrations. As the rotating speed increases, the oxidation activity of formic acid and methanol decrease under voltammetric measurements. The peak currents of formic acid and methanol oxidation increased with the increase in the scan rate and concentration.

scholarly journals Effect of pH on the Electrochemical Redox Behavior of Co2+ in Acetate Buffer Solution

2017 ◽  
Vol 65 (2) ◽  
pp. 107-112
Author(s):  
Ahsanul Kabir ◽  
Humaira Yeasmin ◽  
Md Abu Hasan ◽  
MS Rahman ◽  
MA Hoque ◽  
...  
Keyword(s):  
Metal Ion ◽  
Anodic Peak ◽  
Acetate Buffer ◽  
Acetate Buffer Solution ◽  
Reverse Direction ◽  
Cyclic Voltammograms ◽  
Redox Behavior ◽  
Buffer Solution ◽  
Scan Rate ◽  
Electrochemical Redox

The electrochemical redox behavior of transition metal ion Co2+ at different pH in acetate buffer solution has been investigated using cyclic voltammetry and differential pulse voltammetry at glassy carbon electrode (GCE). In cyclic voltammograms (CVs), Co2+ shows a pair of cathodic and a pair of anodic peak. The peak potential separation and peak current ratio reveals that the redox process of the redox couples, Co2+/Co+ and Co+/Co followed a quasi-reversible behavior and are two step one-electron transfer processes. The electrochemical processes are diffusion controlled. The nature of CV of Co2+ has greatly influenced by the potential scan rate and solution pH. With increasing scan rate both cathodic peaks shifted towards negative potential and first cathodic peak was eventually diminished. In the reverse direction, unexpected behavior such as distinguishable second anodic peak, identical heights of two anodic peaks, three humps like peaks and finally domination of second anodic peak were noticed. However, in lower pH all the above mentioned behavior appeared with higher scan rate. While at higher pH of the solution the peculiar behavior was found at lower scan rate. Nevertheless, at pH 6.5, it demonstrated intense cathodic peaks and a very large anodic peak at all scan rates. Dhaka Univ. J. Sci. 65(2): 107-112, 2017 (July)

AlCl3 and liquid Al assisted extraction of Nd from NaCl–KCl melts via intermittent galvanostatic electrolysis

RSC Advances ◽  
2014 ◽  
Vol 4 (76) ◽  
pp. 40352-40358 ◽  
Author(s):  
Xing Li ◽  
Yong-De Yan ◽  
Mi-Lin Zhang ◽  
Yun Xue ◽  
Hao Tang ◽  
...  
Keyword(s):  
Cyclic Voltammograms ◽  
Melt Temperature ◽  
Galvanostatic Electrolysis ◽  
Assisted Extraction ◽  
Scan Rate

A comparison of the cyclic voltammograms obtained on the W (dotted line) and liquid Al (solid line) electrodes in a NaCl–KCl–NdCl3 (2 wt%) melt. Temperature: 1003 K, scan rate: 0.1 V s−1.

Electrochemical behaviour of silver in aqueous chromate solutions

1998 ◽  
Vol 76 (8) ◽  
pp. 1156-1161 ◽  
Author(s):  
Sayed S Abd El Rehim ◽  
Magdy AM Ibrahim ◽  
Hamdy H Hassan ◽  
Mohammed A Amin
Keyword(s):  
Cyclic Voltammetry ◽  
Electrochemical Behaviour ◽  
Anode Surface ◽  
Cyclic Voltammograms ◽  
Oxidation Peak ◽  
Surface Layers ◽  
Compact Layer ◽  
X Ray ◽  
Solid Films ◽  
Scan Rate

The electrochemical behaviour of silver was studied under cyclic voltammetry and chronoamperometry conditions in aqueous K2CrO4 solutions. The forward cyclic voltammograms exhibited one oxidation peak, A1, due to the formation of Ag2CrO4. The height of the anodic peak, A1, increases with increasing chromate concentration, temperature, and scan rate. The solid films formed on the anode surface have been examined by X-ray diffractometry. The reverse voltammograms exhibited two reduction peaks, C1 and C2, indicating the formation of two distinct surface layers of Ag2CrO4, an inner compact layer reduced in peak C1 and an outer powdery layer reduced in peak C2.Key words: silver electrode, cyclic voltammetry, K2CrO4 solutions.

scholarly journals Cyclic and square-wave voltammetry for selective simultaneous NO and O<sub>2</sub> gas detection by means of solid electrolyte sensors

2020 ◽  
Vol 9 (2) ◽  
pp. 355-362
Author(s):  
Anastasiya Ruchets ◽  
Nils Donker ◽  
Jens Zosel ◽  
Daniela Schönauer-Kamin ◽  
Ralf Moos ◽  
...  
Keyword(s):  
Cyclic Voltammetry ◽  
Solid Electrolyte ◽  
Square Wave Voltammetry ◽  
Limit Of Detection ◽  
Inert Gases ◽  
Cyclic Voltammograms ◽  
Square Wave ◽  
Temperature Range ◽  
Wave Voltammetry ◽  
Scan Rate

Abstract. Solid electrolyte gas sensors (SESs) based on yttria-stabilized zirconia (YSZ) are suitable to detect traces of redox components in inert gases. Usually, their signals are generated as a voltage between two electrodes at open circuit potential or as a current flowing between constantly polarized electrodes. In these rather stationary modes of operation, SESs often lack the desired selectivity. This drawback can be circumvented if SESs are operated in dynamic electrochemical modes that utilize the differences of electrode kinetics for single components to distinguish between them. Accordingly, this contribution is directed to the investigation of cyclic voltammetry and square-wave voltammetry as methods to improve the selectivity of SESs. For this, a commercial SES of the type “sample gas, Pt|YSZ|Pt, air” was exposed to mixtures containing NO and O2 in N2 in the temperature range between 550 and 750 ∘C. On cyclic voltammograms (CVs), NO-related peaks occur in the cathodic direction at polarization voltages between −0.3 and −0.6 V at scan rates between 100 and 2000 mV s−1 and temperatures between 550 and 750 ∘C. Their heights depend on the NO concentration, on the temperature and on the scan rate, providing a lower limit of detection below 10 ppmv, with the highest sensitivity at 700 ∘C. The O2-related peaks, appearing also in the cathodic direction between −0.1 and −0.3 V at scan rates between 100 and 5000 mV s−1, are well separated from the NO-related peaks if the scan rate does not exceed 2000 mV s−1. Square-wave voltammograms (SWVs) obtained at a pulse frequency of 5 Hz, pulses of 0.1 mV and steps of 5 mV in the polarization range from 0 to −0.6 V also exhibit NO-related peaks at polarization voltages between −0.3 and −0.45 V compared to the Pt–air (platinum–air) electrode. In the temperature range between 650 and 750 ∘C the highest NO sensitivity was found at 700 ∘C. O2-related peaks arise in the cathodic direction between −0.12 and −0.16 V, increase with temperature and do not depend on the concentration of NO. Since capacitive currents are suppressed with square-wave voltammetry, this method provides improved selectivity. In contrast to cyclic voltammetry, a third peak was found with square-wave voltammetry at −0.48 V and a temperature of 750 ∘C. This peak does not depend on the NO concentration. It is assumed that this peak is due to the depletion of an oxide layer on the electrode surface. The results prove the selective detection of NO and O2 with SESs operated with both cyclic voltammetry and square-wave voltammetry.

scholarly journals Electrochemical reversibility of Me6Fc/Me6Fc+PF6- and Me8Fc/Me8Fc+PF6- redox systems in acetonitrile

2021 ◽  
Author(s):  
Nigar Z. Ibrahimova ◽  
Gazanfar M. Jafarov ◽  
Dilgam B. Tagiyev ◽  
Iltifat U. Lyatifov
Keyword(s):  
Redox Potential ◽  
Methyl Groups ◽  
Cyclic Voltammograms ◽  
Redox Potentials ◽  
Redox Systems ◽  
Internal Reference ◽  
Donor Property ◽  
Optimal Position ◽  
Electrochemical Reversibility ◽  
Scan Rate

Two new redox systems, sym. 1,2,4,1¢,2¢,4¢-hexamethylferrocene/cation sym. 1,2,4,1¢,2¢,4¢-hexamethyl ferricinium and sym. octamethylferrocene/cation sym. Octamethyl­ferricinium (MenFc/MenFc+, n = 6, 8) were studied by the cyclic voltammetry method. The observed dif­ference between potentials of anodic and cathodic peaks of 0.063 to 0.075 V, and its inde­pendence on the potential scan rate, the straight-line depen­dence of the current value of anodic (and cathodic) peak on square root of the potential scan rate, as well as  shapes of the recorded cyclic voltammograms indicate that both redox systems in acetonitrile meet the most important requirement of IUPAC regarding internal reference redox systems (IRRS) - electrochemical reversibility of electron transfer reaction. The same method under identical conditions was used to study the effect of the number of methyl groups on the redox potential of MenFc/MenFc+ systems, n = 0, 6, 8, 10. It was shown that the successive displacement of half-wave potential in the series of Fc/Fc+ - Me6Fc/Me6Fc+ - Me8Fc/Me8Fc+ -Me10Fc/Me10Fc+ towards negative potentials is attributed to the electron-donor property of methyl groups. The location of the redox potentials values of new systems [n=6 (111 mV), n=8 (23 mV)] between redox potentials of systems of n = 0 (431 mV) and n = 10 (-77 mV) means that the redox potential of the systems of MenFc/MenFc+(n = 6, 8) has an optimal position on the electrode potential scale, i.e. meets another of the IUPAC criteria for IRRS.

Investigation on the Electrochemical Behaviors of Phenol Oxidation on GCE (Glassy Carbon Electrode)

2013 ◽  
Vol 652-654 ◽  
pp. 1684-1687
Author(s):  
Yan Wang ◽  
Shao Qing Zuo ◽  
Huai Gong Zhu
Keyword(s):  
Transport Process ◽  
Oxidation Reaction ◽  
Supporting Electrolyte ◽  
Phenol Oxidation ◽  
Cyclic Voltammograms ◽  
Carbon Electrode ◽  
Electrochemical Behaviors ◽  
Mass Transport Process ◽  
Scan Rate ◽  
Electro Oxidation

Cyclic voltammograms were carried out to track the process of phenol electro-oxidation on GCE, understand the course and further guide the use in dealing with waste water. The effect of supporting electrolyte, phenol concentration, and scan rate were all tested. The results show that phenol oxidation contains several steps, and the first step is a mass transport process, while the following steps are not. What’s more, alkaline solution facilitates the first step, but the produced polymer can foul GCE and hinder the oxidation reaction in turn.

Pb Electrodeposition in the Presence of Chlorine Ions on Cu(100): An in Situ Optical Reflectivity Difference Study

2003 ◽  
Vol 781 ◽  
Author(s):  
J. Gray ◽  
W. Schwarzacher ◽  
X.D. Zhu
Keyword(s):  
Oblique Incidence ◽  
Opposite Sign ◽  
Bulk Phase ◽  
Phase Layer ◽  
Optical Reflectivity ◽  
Scan Rate ◽  
Different Types ◽  
Chlorine Ions ◽  
High Overpotentials

AbstractWe studied the initial stages of the electrodeposition of Pb in the presence of chlorine ions on Cu(100), using an oblique-incidence optical reflectivity difference (OIRD) technique. The OI-RD results reveal that immediately following the underpotential deposition (UPD) of the first Pb monolayer, two different types of bulk-phase films grow depending upon the magnitude of overpotential and cyclic voltammetry (CV) scan rate. At low overpotentials and/or slow scan rates, we propose that a bulk-phase Pb film grows on top of the UPD monolayer. At high overpotentials and/or fast scan rates, either a PbO, PbCl2, or a rough Pb bulk-phase layer grows on top of the UPD layer such that the reflectivity difference signal from such a film has an opposite sign.

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