Potentials of zero total and zero free charge of platinum group metals

Frumḳin, A.; Петрий, О. А.

doi:10.1016/0013-4686(75)90017-1

Cited by 221 publications

(174 citation statements)

References 35 publications

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“…Different methodologies have been developed for the determination of the pzc of different metals [1][2][3][4][5]. Historically, most of the theories of interfacial electrochemistry were developed for mercury electrodes, where pzc measurements can be easily achieved from electrocapilary curves [6].…”

Section: Introductionmentioning

confidence: 99%

“…Secondly, the meaning itself of the concept of charge is obscured by the interference of adsorption processes that involve charge transfer [3,4]. In this regards, it turns out that it is not possible to unambiguously discriminate only from macroscopic electrochemical measurements whether there is a true charge separation at the interfase (true capacitive charge) from a situation where charge has been redistributed to form covalent bonds between the surface and the adsorbed species (pseudocapacity phenomena).…”

Section: Introductionmentioning

confidence: 99%

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

Rizo

Sitta

Herrero

et al. 2015

Electrochimica Acta

149

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: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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

Rizo

Sitta

Herrero

et al. 2015

Electrochimica Acta

149

199

View full text Add to dashboard Cite

show abstract

“…However, because the charge that flows remains localised on the surface of the electrode in the form of adsorbed species, thermodynamic equations can be easily extended to this case, just by the introduction of the notion of the total charge [12][13][14].…”

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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“…In the case of hydrogen and hydroxyl adsorbing metals, the study of the pH dependence of the total and free charge contains valuable information about the structure of the interface and the state of adsorbed hydrogen and OH species [6]. Recently, experiments have been carried out in a wide pH range, involving an acidic region pH<4 and an alkaline region pH>8 [7,10].…”

Section: Introductionmentioning

confidence: 99%

“…Regarding the interfacial charge, when adsorption processes participate in the formation of the interphase, distinction should be made between the concepts of total charge (including the charge involved in adsorption processes) and free charge (true electronic charge). Correspondingly, different values for the potential of zero total charge (pztc) and zero free charge (pzfc) should be defined [2,6]. This is the situation for Pt and other electrocatalytic metals.…”

Section: Introductionmentioning

confidence: 99%