Determination of the potential of zero charge of Pt/CO electrodes using an impinging jet system
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ORIGINAL PAPER
Determination of the potential of zero charge of Pt/CO electrodes using an impinging jet system A. Boronat-González 1 & E. Herrero 1
&
J. M. Feliu 1
Received: 10 May 2020 / Revised: 10 May 2020 / Accepted: 14 May 2020 # Springer-Verlag GmbH Germany, part of Springer Nature 2020
Abstract In this manuscript, the potential of zero charge (pzc) of platinum single-crystal electrodes has been determined using the impinging jet system and recording the transient associated with the interphase formation. Initially, the Pt(111), Pt(110), and Pt(100) electrodes covered with CO were used. To demonstrate the validity of the procedure, the values obtained for the pzc of these electrodes were compared with those previously reported in the literature and also with those expected from work function changes. An excellent agreement has been found. After that, the values for the pzc of the stepped surfaces having (111) terraces and (110) steps were determined. For these surfaces, the pzc initially diminishes as the step density increases, in accordance with the expected diminution of the work function due to the Smoluchowski effect on the step site. However, for the shorter terraces, the pzc value increases with the step density, probably because of step dipole-dipole coupling due to the presence of a CO layer on the electrode. Keywords Platinum single-crystal electrodes . Potential of zero charge . Interphase properties . Adsorbed CO . Impinging jet system
Introduction The properties of the electrode/solution interface govern the electrochemical reactivity, and many efforts have been devoted to characterizing it. This way, a relationship between its properties and the observed electrochemical performance can be obtained, allowing establishing a detailed reaction mechanism, a required step in finding more efficient materials and conditions for the reaction. Within the properties of the interphase, the effects in the reactivity of the surface structure and composition of the electrode, as well as the composition of the electrolyte, have been studied in detail, although a meticulous and complete explanation on how they modify the reactivity for a given reaction has not been reached yet. On the other hand, the effects of other interfacial properties have been less studied, even though their effects can be as relevant in
* E. Herrero [email protected] * J. M. Feliu [email protected] 1
Institute of Electrochemistry, Universidad de Alicante, Apdo 99, 03080 Alicante, Spain
controlling the reactivity as those observed for the aforementioned properties. Among these, the surface charge of the electrode is a key property. The significant effects of the surface charge in the reactivity are known for decades. The pioneering works of Frumkin revealed that the repulsive electrostatic interactions between the negatively charged surface and a peroxodisulfate anion resulted in a significant diminution of the reduction reaction rate of this anion [1]. But the surface charge not only generates electrostatic interactions but also alter
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