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

Rizo, Rubén; Sitta, Elton; Herrero, Enrique; Climent, Vı́ctor; Feliu, Juan M.

doi:10.1016/j.electacta.2015.01.069

Cited by 155 publications

(240 citation statements)

References 59 publications

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“…As has been shown by previous work [39][40][41] , while the pzfc cannot be directly measured, an estimation can be obtained from values of CO charge displacement experiments. This is achieved by extrapolating the charge in the double layer region either into the hydrogen adsorption region (acid solutions) or into the hydroxyl adsorption region (alkaline solutions).…”

Section: Resultsmentioning

confidence: 99%

“…This means that pzfc changes from the double layer region (0.34 VRHE) in acidic solutions to the onset of the surface oxidation (ca. 1.0 VRHE) in strongly alkaline solutions 40 . As a consequence, at a given potential on the RHE scale, the strength of the electric field and the energy associated with the (re)organization of interfacial solvent molecules will depend on pH.…”

Section: Resultsmentioning

confidence: 99%

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Interfacial water reorganization as a pH-dependent descriptor of the hydrogen evolution rate on platinum electrodes

et al. 2017

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The hydrogen evolution on platinum is a milestone reaction in electrocatalysis as well as an important reaction towards sustainable energy storage. Remarkably, the pH dependent kinetics of this reaction is not yet fully understood. Here, we present a detailed kinetic study of the hydrogen adsorption and evolution reaction on Pt(111) in a wide pH range. Impedance and Tafel slope measurements show that the hydrogen adsorption and hydrogen evolution are both slow in alkaline media, which is consistent with the observation of a shift in the rate-determining step for H2 evolution.Adding nickel to the Pt(111) surface lowers the barrier for the hydrogen adsorption rate in alkaline solutions and thereby enhances the hydrogen evolution rate. These observations are explained by a new model which highlights the role of the reorganization of interfacial water to accommodate charge transfer through the electric double layer, the energetics of which is controlled by how strongly water interacts with the interfacial field. The new model is supported by laser-induced temperature-jump measurements. Our model sheds new light on the origin of the slow kinetics for the hydrogen evolution reaction in alkaline media.

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Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Interfacial water reorganization as a pH-dependent descriptor of the hydrogen evolution rate on platinum electrodes

et al. 2017

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“…In this region, if there are no adsorption processes, total and free charge coincide, and, under this assumption, free charge values in this region can be obtained from the total charge curves mentioned above. It has been shown previously how this region can be extrapolated into the hydrogen region to obtain the pzfc [14,[21][22][23]. This strategy, which is only applicable to Pt(111) and not to the other basal planes, is illustrated in Figure 1.…”

Section: Model For the Calculation Of The Pzfc Of Pt(111)mentioning

confidence: 99%

“…At pH=3 pztc and pzfc coincide in the double region. We have previously proposed that this pH has a particular meaning that can be identified with the pK of adsorbed water [22].…”

Section: E V Vs Shementioning

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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“…This is the situation for Pt and other electrocatalytic metals. In these cases, the usually available magnitude is the total charge, from which the free charge can be calculated by using some reasonable assumptions [7][8][9][10]. In general, the pztc and the pzfc of Pt(111) have been evaluated in acidic solution [8,9].…”

Section: Introductionmentioning

confidence: 99%