Hydrogen Electrode Reaction Research Articles

Kinetics of Hydrogen Electrode Reaction on Mercury. II. Experimental Part. Elucidation of Non-steady State by Constant Potential and Linear Potential-sweep Methods

Abstract Potentiostatic and potentiodynamic experiments on Hg in 1 M HCl, HBr, and HI solutions were carried out to elucidate transient phenomena of the electrochemical mechanism of the hydrogen electrode reaction. The results obtained by both methods agree with the analysis of the non-steady state based on the electrochemical mechanism. The large effect of anions on the transient phenomena is satisfactorily interpreted by the change of repulsive force energy between H2+(a)’s on electrode, which is caused by the presence of specifically adsorbed anions in various degrees. The potential-sweep method reveals features of the step preceding the rate-determining step and gives the value of the repulsive force energy between H2+(a)’s as expected by the analysis.

Change of mechanism of the hydrogen-electrode reaction with overpotential—II. hydrogen pressure equivalent to hydrogen overpotential and its relevance to the hydrogen embrittlement of metals

Electrochemical aspects of the hydrogen embrittlement are discussed in terms of a possible mechanism change of the hydrogen-electrode reaction occurring at the surface of the metal. Hydrogen pressure equivalent to hydrogen overpotential is formulated for the discharge-combination and the discharge-ion + atom-desorption routes in general forms, including the cases with comparable magnitudes of exchange cds of the constituent steps. The hydrogen pressure data observed by DeLuccia et al on iron in acidic solution are analysed. It is demonstrated that the data are well explained on the basis of the model that the hydrogen-electrode reaction on iron proceeds through the discharge-combination route with the exchange cd of the discharge step about one order of magnitude lower than that of the combination step.

Change of mechanism of the hydrogen-electrode reaction with overpotential—I. distribution of the reaction affinity among constituent steps

Kinetic analysis is carried out of the hydrogen-electrode reaction without assuming a unique rate-determining step (the case of coupled control). Two rection routes, the discharge-catalytic-combination and the discharge-ion + atom desorption, are considered. Equations are derived which describe the distribution of the reaction affinity among a constituent steps. It is demonstrated that the reaction affinity may be more or less evenly distributed among the steps and yet there exists general tendency that the over-all rate under strong cathodic polarization obeys a rate expression for the slow-discharge mechanism rather than the slow-combination or the slow-ion + atom-desorption mechanism, whereas either of the latter mechanisms can explain the results of high anodic polarization.

Kinetics of electrode reactions in liquid ammonia. Part 1.—Hydrogen electrode in acid solution

A kinetic study has been made of the hydrogen electrode reaction in liquid ammonia at low temperatures using steady and non-steady state techniques. The reaction has been shown to be less reversible than in aqueous solutions and this is attributed to inhibition by materials adsorbed on the platinum surface which arise from the decomposition of the solvent.

Cyclic voltammetry at the iron electrode in high temperature aqueous sodium hydroxide solutions

The cyclic sweep polarization behaviour of iron in sodium hydroxide solutions in the temp. range 200–250°C is investigated using a new pressure-balanced electrochemical cell which is fully described. It is shown that the corrosion of iron in this environment takes place at a potential which is controlled by the hydrogen electrode reaction. Active dissolution of the metal is not observed, confirming the existence of a solid-state barrier layer between the metal and the solution in the porous oxide.

Catalytic Activity and Mechanism for Hydrogen Electrode Reaction

Catalytic Activity and Mechanism for Hydrogen Electrode Reaction

Chemisorption and catalytic reactions of hydrogen at metal surfaces

The central problem awaiting solution in the field of metal catalysis is the relation between catalytic activity and solid state properties through the intermediate surface complexes. Attention is drawn to interrelations between solid state properties. Published information on the activities of the transition metals for reactions involving hydrogen (chemisorption, atom recombination, para-hydrogen conversion, hydrogen electrode reaction) is briefly reviewed: uncertainties in previous attempts to calculate hydrogen-metal bond strengths are emphasized. The description of metallic bonding in molecular orbital language is outlined and its implication for the understanding of surface processes is sketched.

On the impedance of galvanic cells XXV. The double-layer capacitance of the dropping mercury electrode in 1 M HCl, 7.5 M and 5.2 M HClO4 and the kinetic parameters of the hydrogen electrode reaction as a function of temperature in these solutions

The impedance of the dropping mercury electrode in aqueous solutions in 1 M HCl, 7.5 M HCl and 5.2 M HClO 4 , saturated with hydrogen at one atmosphere was measured at temperatures between −39° and +72° both in and outside the potential region where the electrode reaction, e +H + H 2 , proceeds. Analysis of the impedance data gave information about both the kinetics of the electrode reaction and the double-layer capacity. Exchange current densities and transfer coefficients are reported. The apparent heat of activation is 21.1 kcal mole −1 for 1 M HCl, 19.5 kcal mole −1 for 5.2 M HClO 4 , and 11.1 kcal mole −1 for 7.5 M HCl. In the latter solution the transfer coefficient is found to be a linear function of temperature. In 1 M HCl and 5.2 M HClO 4 the transfer coefficient is virtually independent of temperature. In 1 M HCl the hump in the capacity curve is situated anodically to the potential of zero charge but in 7.5 M HCl and 5.2 M HClO 4 this is reversed. In both 1 M HCl and 7.5 M HCl the capacity-potential curves show one potential where the double-layer capacitance is independent of temperature. In the case of 5.2 M HClO 4 , this occurs at two potentials, situated at either side of the potential of zero charge.

On the impedance of galvanic cells: XXV. The double-layer capacitance of the dropping mercury electrode in 1 M HCl, 7.5 M HCl and 5.2 M HClO 4 and the kinetic parameters of the hydrogen electrode reaction as a function of temperature in these solutions

The impedance of the dropping mercury electrode in aqueous solutions in 1 M HCl, 7.5 M HCl and 5.2 M HClO4, saturated with hydrogen at one atmosphere was measured at temperatures between −39° and +72° both in and outside the potential region where the electrode reaction, e+H+ H2, proceeds.

Kinetic isotope effects in the hydrogen electrode reaction

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTKinetic isotope effects in the hydrogen electrode reactionJ. D. E. McIntyre and M. SalomonCite this: J. Phys. Chem. 1968, 72, 7, 2431–2434Publication Date (Print):July 1, 1968Publication History Published online1 May 2002Published inissue 1 July 1968https://doi.org/10.1021/j100853a026RIGHTS & PERMISSIONSArticle Views143Altmetric-Citations6LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InReddit PDF (442 KB) Get e-Alerts

Kinetics of the hydrogen electrode reactionon gold in acid sulphate melts

The hydrogen-electrode reaction on gold prepared in different ways has been investigated in molten acid sulphates at temperatures from ca 180 to 345°C. Potentiostatic and galvanostatic measurements under steady conditions were performed and the evolution of the potential of the working electrode when current was switched on and off was recorded.Current/voltage curves followed a Tafel law at cathodic overvoltages higher than 0-050 V. Slopes ranging from RT/2F to about 2RT/F are reported, depending on the preparation of the electrode, temperature and overvoltage region considered. Anodic current/voltage curves exhibit a limiting current. From the linear overvoltage/current region the reaction resistance was estimated for the anodic reaction. The exchange cds calculated from the reaction resistance agree with the values extrapolated from the Tafel lines having a slope RT/2F, if the stoichiometric number involved in the mechanism of the reaction is one.Electrode potential decayed logarithmically with time. Experimental electrode capacitances were evaluated from the time dependence of electrode potential.The hydrogen-electrode reaction is discussed in terms of a mechanism involving a fast hydrogenion discharge followed by a combination reaction as rate-determining step. The behaviour of the hydrogen-electrode reaction on gold in acid sulphate melts resembles that in aqueous acid solutions at ordinary temperatures.

A Study on Aqueous Corrosion of Metals

The measurement of polarization in metals in electrolytic solutions is an effective method of determining the corrosion rate and its mechanism because the local action of the cell on the metal surface, which is one of the typical electrochemical phenomena, is considered to be the causative of aqueous corrosion of metals in general. To this general statement, however, there are limitations as follows:(1) That even with perfect polarization of the metal its active sites on the surface remain constant.(2) That the mechanism of the anodic and the cathodic reactions remain as it is for a wide range of polarization.Through experiments of examining iron pieces of different species, for their contamination at 40°C, in aqueous solution of sulfuric acid, as it was or in the same solution with ferrous ion, the parameters of hydrogen electrode reactions on the metal cathode, their Tafel coefficient, and their exchange current density were obtained as well as their static potential and corrosion current density. The hysteresis on the potential vs. current density curve with increasing and decreasing current was observed in all the sample species while the potential vs. log current density curve made a straight line when the surface of the electrode was sufficiently stabilized by electrolysis at high current density in pure solution of the acid.The report of the experiments is concluded with demonstration to prove that the measurement of polarization is still an effective method of corrosion test.

The hydrogen-electrode reaction in the isotopically mixed system—I. The relation between forward and backward unidirectional rates and evaluation of the stoichiometric number of the rate-determining step

A general consideration of the possible reaction routes of the hydrogen-electrode reaction leads to the classification of all the conceivable mechanisms into two groups according to the value of the stoichiometric number, ν, of the rate-determining step. The previous treatment on the validity, in the isotopically mixed system, of the relation between the forward unidirectional rate of the over-all reaction, V f , its backward rate, V b , the overpotential, η, and ν; V f / V b = exp (− 2 Fη/ν RT), is re-investigated rigorously on the basis of general considerations. It is shown, in agreement with the previous conclusion, that this relation holds invariably irrespective of the isotope content and of the magnitude of the isotope effect, provided that V f and V b are replaced by the respective sums of contributions of both isotopes, and η by the potential of the test electrode referred to its rest potential in the same isotopically mixed system. Based on the relation thus verified, a method is advanced that enables us to determine experimentally (a) ν by combining the rate of isotopic exchange with the polarization resistance of the electrode used as the catalyst, without neglecting the isotope effect, and (b) the magnitude of the isotope effect from similar data. For the hydrogen-electrode reaction on nickel in an alkaline solution, ν has been determined to be 1·0 and the deuterium separation factor in the hydrogen ionization reaction to be 1·5.

The hydrogen-electrode reaction in the isotopically mixed system—II. Evaluation of the electrolytic separation factor of deuterium from the rest potential of the hydrogen electrode in the deuterium-containing system

The rest potential, E r, of the hydrogen electrode in deuterium-containing hydrogen and a solution of light water as referred to the reversible hydrogen electrode in the light hydrogen and the same solution is formulated as a function of deuterium content of the gaseous hydrogen and the deuterium separation factor, S b, in the hydrogen ionization reaction. It is shown that the relation is not significantly affected by the operative mechanism of the hydrogen-electrode reaction. Consequently, the relation provides a convenient method of evaluating S b from the observation of E r. Experiments were carried out on Pt, Ni, Au and Ag in the system composed of deuterium-containing hydrogen and light water. The value of S b as evaluated from E r was practically independent of the deuterium content in the gaseous hydrogen. The values obtained were 1·1 for Pt in acidic and alkaline solutions, 1·6 for Ni in alkaline solution, 1·2 for Au and 1·5 for Ag, both in acidic solution. These values multiplied by the partition coefficient of deuterium between hydrogen and water (4·0 at room temperature) give approximate values of the deuterium separation factor in the hydrogen evolution reaction.

Discussion of “The Pressure Coefficients of the Hydrogen Electrode Reaction” [G. J. Hills and D. R. Kinnibrugh (pp. 1111–1120, Vol. 113, No. 11)

not Available.

The Pressure Coefficient of the Hydrogen Electrode Reaction

The various criteria for the mechanism of the hydrogen electrode reaction are considered with particular reference to the pressure coefficient of the reaction rate. The techniques of studying electrode processes at pressures up to 1500 atm are described, and the volume of activation derived for the hydrogen evolution reaction has been found to be −3.4 ml mole−1. This negative value is not in accord with either of the two mechanisms usually proposed for this reaction. It suggests that the rate‐determining step is the stage i.e., the emission and hydration of metallic electrons.

Periodic Variation of Exchange Current Density of Hydrogen Electrode Reaction with Atomic Number and Reaction Mechanism

A survey of recent results shows that the activity is a periodic function of the atomic number for each long period. It is concluded that the bulk properties of electrode dominate its activity. Also, decreases linearly with heat of adsorption or increases linearly with work function for the transition metals, but remains unchanged for the metals following them (the ascending metals). These relations are qualitatively interpreted by the catalytic and the electrochemical mechanism for the transition and the ascending metals, respectively.

Platinum Metal Alloys in Electrocatalysis

The relative electrocatalytic activities of some binary platinum alloys for the oxidation and ionisation of hydrogen and the anodic oxidation of methanol are briefly described. For the hydrogen electrode reaction in acid solution the ruthenium-platinum and rhodium-platinum alloys are generally not as active as bright platinum itself. This is also found for the anodic oxidation of methanol in acid solution. At the low voltametric “sweep” rates used in the latter experiments the activities are somewhat greater on the reverse scan, from high to low positive potentials, than on the forward scan.

Tritium separation factor of slow discharge mechanism of hydrogen electrode reaction.

Tritium separation factor of slow discharge mechanism of hydrogen electrode reaction.

Isotopic separation factor of slow discharge mechanism of hydrogen electrode reaction. II.

The electrolytic separation factor of deuterium was calculated on the basis of the slow discharge mechanism assuming that the proton or deuteron is discharged from the water molecule as H/sub 2/O + e yields H + OH/sup -/ or DHO + e yields D + OH/sup -/. The results were in agreement with those obtained assuming that the proton or deuteron discharged was that of the hydroxyl ion. (M.C.G.)