On the Thermodynamics of Hydrogen Adsorption at Pt Electrodes

• Published in: Russian journal of electrochemistry Vol. 58; no. 10; pp. 891 - 895
• Main Authors: Safonov, V. A., Lipkowski, J.
• Format: Journal Article
• Language: English
• Published: Moscow Pleiades Publishing 01-10-2022; Springer Nature B.V
• Subjects: Adsorption; Chemistry; Chemistry and Materials Science; Depletion; Electrochemistry; Electrodes; Electrolytes; Equilibrium conditions; Hydrogen; Hydrogen atoms; Hydrogen ions; Hydronium ions; Ion concentration; Physical Chemistry; Single crystals; Surface chemistry; Surface energy; Thermodynamics; total and free surface charges; Gibbs adsorption and surface concentrations of hydrogen atoms and ions; electrocapillary curves
• ISSN: 1023-1935; 1608-3342
• DOI: 10.1134/S1023193522100111

In the mid 1960th–early 1970th, A. Frumkin and O. Petrii investigated the adsorption of hydrogen at a platinized platinum electrode surface performing measurement of a change in the hydronium ion concentration when the large surface area electrode was immersed into an electrolyte solution at the fixed potentials in the hydrogen adsorption region under equilibrium conditions. The depletion (or increase) of the hydronium ions in the electrolyte bulk corresponded to the amount of hydrogen ions adsorbed at the electrode surface. They derived an equation relating the amounts of adsorbed hydrogen (atoms and ions) to the change of surface energy. A several decades later Guelph–Alicante team employed the Gibbs–Duhem equation to determine the amount of hydrogen atoms adsorbed at a small Pt single crystal electrode from the measurement of the total charge at the Pt surface. This paper compares the thermodynamic basis of the two types of measurements and demonstrates that despite differences between the nature of the two experiments their thermodynamic foundations are equivalent.