The study of the properties defining the electrochemical interface is fundamental to rationalize the synthesis and development of new materials that could increase the efficiency of reactions for technological applications, such as energy conversion and storage. The behavior of the interfacial water structure has been proposed as one of the parameters that could affect the reactivity of the electrochemical reactions in aqueous solutions. In most cases water is a reactant/product of electrocatalytic reactions taking place in the electrified interface. Previous works have reported that the water structure is related with the interfacial electric charge, which depends on the electrode potential shift from the potential of zero charge, thus involving the surface structure and composition of the electrode, and also the pH and composition of the solution side. In spite of different studies showing the influence of the cations in the electrocatalysis of several reactions, there are no works pointing out the effect of these cations on the interfacial water structure. In this work, a direct evidence of the effect of the nature of the alkali metal cation on the water adlayer structure is demonstrated on Pt(111) electrodes in absence of specific adsorbed anions. This evidence has been determined by measurements of the interfacial electric field by using the laser-induced temperature jump technique, which directly affects the structure of water at the interface. The influence in the reactivity of hydrogen peroxide inhibition will be discussed. It is known that this process is sensitive to the interfacial charge of the Pt(111) electrode since the diffusion-controlled reaction is inhibited at low potentials, in close relation to the potential of zero free charge.

Cation effects on interfacial water structure and its influence on hydrogen peroxide reduction on Pt(111) electrodes

ACS Spring Meeting 2021

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