Steady-state voltammetry of strong and weak acids with and without supporting electrolyte

Ciszkowska, Małgorzata; Stojek, Zbigniew; Morris, Susan E.; Osteryoung, Janet

doi:10.1021/ac00044a013

Cited by 97 publications

(76 citation statements)

References 6 publications

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“…Both approaches showed a linear relationship between current density and phosphate concentration. This linear dependency has already been observed by other authors in the steady state limiting reduction current with other weak acids such as acetic, ascorbic, monochloroacetic, lactic and HSO À 4 [43][44][45]. Nevertheless, the dependency between current density and weak acid concentration has not always been found to be linear [34,35] because higher acid concentration induced a higher free proton concentration (reaction (8)) and, following Eq.…”

Section: Voltammetric Studymentioning

confidence: 59%

“…The electrochemical reduction of phosphates and other weak acids on various electrodes has been the subject of several investigations [29,[34][35][36][37][38][39][40][41][42][43][44][45]. The most widely accepted mechanism for the reduction of weak acids is of the CE (chemical-electrochemical) type, where the dissociation of the acid takes place before the electrochemical reduction of free protons [32][33][34]:…”

Section: Weak Acid Reduction Mechanismsmentioning

confidence: 99%

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Role of the reversible electrochemical deprotonation of phosphate species in anaerobic biocorrosion of steels

2007

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Sulphate reducing bacteria are known to play a major role in anaerobic microbiological influenced corrosion of steels, but mechanisms behind their influence are still source of debates as certain phenomena remain unexplained. Some experiments have shown that hydrogen consumption by SRB or hydrogenase increased the corrosion rate of mild steel. This was observed only in the presence of phosphate species. Here the cathodic behaviour of phosphate species on steel was studied to elucidate the role of phosphate in anaerobic corrosion of steel. Results showed: a linear correlation between reduction waves in linear voltammetry and phosphate concentration at a constant pH value; that phosphate ions induced considerable anaerobic corrosion of mild steel, which was sensitive to hydrogen concentration in the solution; and that the corrosion potential of stainless steel in presence of phosphate was shifted to more negative values as molecular hydrogen was added to the atmosphere in the reaction vessel. Phosphate species, and possibly other weak acids present in biofilms, are suggested to play an important role in the anaerobic corrosion of steels via a reversible mechanism of electrochemical deprotonation that may be accelerated by hydrogen removal.

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Section: Voltammetric Studymentioning

confidence: 59%

Section: Weak Acid Reduction Mechanismsmentioning

confidence: 99%

Role of the reversible electrochemical deprotonation of phosphate species in anaerobic biocorrosion of steels

2007

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“…As already noted, weak acids often dissociate before reduction. This process has been documented on platinum disk microelectrodes, 34,35 suggesting that proton reduction from hydronium is the likely process in either direct hydronium or PyrH + reduction cases. Using the relationship in Equation 4 and approximating hydronium and PyrH + reduction as reversible over the scan rates chosen so that the formal potential, E H A/H 2 0 ∼ = E 1/2 , the E 1/2 values calculated for hydronium and PyrH + protons are estimated to be −0.42 V vs. SCE and −0.55 V vs. SCE, close to that observed experimentally.…”

mentioning

confidence: 78%

Isotopic Probe Illuminates the Role of the Electrode Surface in Proton Coupled Hydride Transfer Electrochemical Reduction of Pyridinium on Pt(111)

Zeitler

Ertem

Pander

et al. 2015

J. Electrochem. Soc.

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A recently proposed mechanism for electrochemical CO 2 reduction on Pt (111) catalyzed by aqueous acidic pyridine solutions suggests that the observed redox potential of ca. −600 mV vs. SCE is due to the one-electron reduction of pyridinium through proton coupled electron transfer (PCET) to form H atoms adsorbed on the Pt surface (H ads ). The initial pyridinium reduction was probed isotopically via deuterium substitution. A combined experimental and theoretical analysis found equilibrium isotope effects (EIE) due to deuterium substitution at the acidic pyridinium site. A shift in the cathodic cyclic voltammetric half wave potential of −25 mV was observed, consistent with the theoretical prediction of −40 mV based on the recently proposed reaction mechanism where pyridinium is essential to establish a high concentration of Brønsted acid in contact with the substrate CO 2 and with the Pt surface. A prefeature in the cyclic voltammogram was examined under isotopic substitution and indicated an H ads intermediate in pyridinium reduction. Theoretical prediction and observation of an EIE supported the assignment of the cathodic wave to the proposed reduction of pyridinium through PCET forming H ads and eventually H 2 on the Pt surface.

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“…Moreover, the analytical importance of monitoring the acid concentration by voltammetry or amperometry instead of potentiometry has been emphasized [1, 2, 10 -12, 16 -19]. It has been found that strong acids, which are completely dissociated, provided a well defined wave due to the reduction of hydrogen ions [1,2,6,8,14] …”

Section: Introductionmentioning

confidence: 99%

Low Frequency Square‐Wave Voltammetry of Weak Acids at Platinum Microelectrodes

2005

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The reduction process of monoprotic weak acids (lactic and acetic acid, and dihydrogen phosphate ion) and mixtures of a strong and a weak acid (perchloric and one of the above weak acids) have been investigated by square-wave voltammetry (SWV) at a platinum microelectrode 12.5 mm radius. The SW measurements have been performed at low frequencies (i.e., 3 Hz), where the heterogeneous electron transfer process, involving hydrogen evolution (2H þ þ 2e ¼ H 2 ), is essentially reversible, and non-planar diffusion conditions prevail in the mass transport. Under these conditions, the forward and the reverse current-potential profiles are sigmoidal, whereas the net current-potential profile is peak shaped. The influence of dissociation constant and analytical concentration of the weak acid on the features of the square-wave voltammograms has been examined in detail. In general, both these characteristics of the weak acids affect the square-wave parameters peak potential (E p ), width at half height (W 1/2 ) and net peak current (i p ) in a complex manner. Their dependence on concentration is due to the 2 : 1 stoichiometry of the heterogeneous electron transfer, while the dissociation constant contribution arises because of the CE mechanism involved in the overall electrode process. The kinetic of the homogeneous reaction has been investigated by the use of the forward current plateau (achieved by the end of the sweep) along with a theoretical equation. Mixtures of a strong and a weak acid can provide one or two waves, depending on the acid strength and on the analytical concentration of each acid. Peak potential differences of about 80 mV are needed to discern two peaks. Calibration plots, examined for all the weak acids, have shown that linearity may exist only over relatively small concentration ranges.

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Steady-state voltammetry of strong and weak acids with and without supporting electrolyte

Cited by 97 publications

References 6 publications

Role of the reversible electrochemical deprotonation of phosphate species in anaerobic biocorrosion of steels

Role of the reversible electrochemical deprotonation of phosphate species in anaerobic biocorrosion of steels

Isotopic Probe Illuminates the Role of the Electrode Surface in Proton Coupled Hydride Transfer Electrochemical Reduction of Pyridinium on Pt(111)

Low Frequency Square‐Wave Voltammetry of Weak Acids at Platinum Microelectrodes

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