High frequency impedance measurements on Pt(111) in sulphuric and perchloric acids

Sibert, Éric; Faure, R.; Durand, Robert

doi:10.1016/s0022-0728(01)00639-8

Cited by 68 publications

(84 citation statements)

References 12 publications

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“…15 µFcm -2 . This value of double layer capacitance is consistent with impedance measurements of this magnitude [48,49]. With this information it could be concluded that pzfc and pztc almost coincided in the case of Pt(111) with a value of 0.32 V SHE.…”

Section: 1charge Evaluationsupporting

confidence: 87%

Towards the understanding of the interfacial pH scale at Pt(1 1 1) electrodes

Rizo

Sitta

Herrero

et al. 2015

Electrochimica Acta

139

199

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Abstract.The determination of the potentials of zero total and free charge, pztc and pzfc respectively, were made in a wide pH range by using the CO displacement method and the same calculation assumptions used previously for Pt(111) electrodes in contact with nonspecifically adsorbing anions. Calculation of the pzfc involves, in occasions, long extrapolations that lead us to the introduction of the concept of potential of zero extrapolated charge (pzec). It was observed that the pztc changes with pH but the pzec is independent of this parameter. It was observed that the pztc>pzec at pH > 3.4 but the opposite is true for pH>3.4. At the latter pH both pzec and pztc coincide. This defines two different pH regions and means that adsorbed hydrogen has to be corrected in the "acidic" solutions at the pztc while adsorbed OH is the species to be corrected in the "alkaline" range. The comparison of the overall picture suggests that neutral conditions at the interface are attained at significantly acidic solutions than those at the bulk.

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Section: 1charge Evaluationsupporting

confidence: 87%

Towards the understanding of the interfacial pH scale at Pt(1 1 1) electrodes

Rizo

Sitta

Herrero

et al. 2015

Electrochimica Acta

139

199

View full text Add to dashboard Cite

show abstract

“…For that reason, the response measured at short times to a fast perturbation of the interphase should allow determination of the free charge. This strategy has been used with the help of impedance spectroscopy measurements at very high potential modulation frequencies [15,16]. However, one limitation common to any potential controlled technique is the existence of a solution resistance that limits the time scale of the potential modulation.…”

mentioning

confidence: 99%

Investigating interfacial parameters with platinum single crystal electrodes

et al. 2017

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The concepts of total and free charge of platinum single crystal electrodes are revised in this paper, together with the associated concepts of potential of zero total and free charge. Total charges can be measured from CO displacement method. Results on solution of different pH are described. A novel buffer composition is used to attain pH values close to neutrality while avoiding interferences from anion adsorption processes. Stress is made on the fact that free charges are not accessible through electrochemical measurement for systems at equilibrium since adsorption processes (hydrogen and hydroxyl) interfere with free charge determination. Still, a model is described that allows, under some assumptions, extract free charge values and the corresponding potential of zero free charge for Pt (111) electrodes. On the other hand, fast measurement outside equilibrium can separate free charges from adsorption processes based on their different time constant. In this way, the laser induced temperature jump experiment allows determination of the potential of maximum entropy, a magnitude that is intimately related with the potential of zero free charge. Values of the potential of maximum entropy as a function of pH are given for the different basal planes of platinum.

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“…The peakshaped potential dependence of C dl values is more prominent for H 2 SO 4 than for HClO 4 solution, indicating adsorption of (bi)sulphate anions in the process faster than double-layer charging. Such a potential dependence of C dl values was already observed [35][36][37][38][39][40] and related either to an indirect effect of rapid adsorption of (bi)sulphate [33,35] and hydroxide ions [39], or to the point of zero electrode charge [36]. For the potential dependence of C H and C A , peak-shaped potential dependences are expected for the Langmuir adsorption statistics [34,35,39,52], where E and h are no longer independent.…”

Section: Impedance Parameter Values and Their Potential Dependencesmentioning

confidence: 74%

“…It is a general imperative in impedance measurements for keeping R s and C dl values small [26,28,37], since these two values determine the highest limit of the frequency window available for kinetic measurements, except when the rate of adsorption is higher than double-layer charging [31,32]. This fast adsorption case, where the high frequency limit for impedance measurements becomes determined by R s , and the not-separable sum of C dl and adsorption pseudo-capacitance are the general causes of high capacitative electrode systems and high apparent double-layer capacitance values.…”

Section: Frequency Dependence Of the Electrode Impedance Involving Admentioning

confidence: 99%

“…Good example for illustration of the first case is the Pt(1 1 1) single crystal electrode in acid electrolyte solutions with high concentration of adsorbates, where analyses of impedance spectra that have been measured by use of conventional instrumentation showed inability or limited ability to extract separately the resistive term (adsorption resistance) and capacitative term (adsorption capacitance) due to adsorption of hydrogen [35,36], (bi)sulphate [34,35] or chloride [34] ions. By use of an advanced set-up configuration for high-frequency measurements [37,38], it was possible, however, to extract the charge transfer kinetic term for adsorption of hydrogen ions, and so to separate adsorption capacitance from the double-layer charging capacitance. In the case of slow adsorption kinetics, only double-layer charging is measured, and again almost featureless, capacitative impedance spectra are expected, such as was obtained for adsorption of phosphate ions at the Pt(1 1 1) electrode [34].…”

Section: Introductionmentioning

confidence: 99%

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