The near-surface ion distribution at the solid–liquid interface during the Hydrogen Oxidation Reaction (HOR)/Hydrogen Evolution Reaction (HER) on a rotating platinum disc electrode is demonstrated in this work. The relation between reaction rate, mass transport and the resulting surface pH-value is used to theoretically predict cyclic voltammetry behaviour using only thermodynamic and diffusion data obtained from the literature, which were confirmed by experimental measurements. The effect of buffer addition on the current signal, the surface pH and the ion distribution is quantitatively described by analytical solutions and the fragility of the surface pH during reactions that form or consume H+ in near-neutral unbuffered solutions or poorly buffered media is highlighted. While the ideal conditions utilized in this fundamental study cannot be directly applied to real scenarios, they do provide a basic understanding of the surface pH concept for more complex heterogeneous reactions.

Near-surface ion distribution and buffer effects during electrochemical reactions.

Kinetic regularities governing reduction of iodate and bromate anions at the dropping mercury electrode in acidified solutions and solutions of cadmium salts are explored. The presence of hidden limiting currents of the first and second kind is established and attributed to a chemical reaction between the hydroxyl ion (the product of the electrochemical reaction) and the hydronium or cadmium ion in the near-electrode layer. Formation of insoluble cadmium hydroxide at the mercury surface, which occurs at a certain cadmium ion concentration, is shown to retard reduction of the anions

O. A. Trushkina

Papers

The hidden limiting currents during the reduction of the second-group anions