Kinetic criteria for the mechanism of the hydrogen evolution reaction

✍ Scribed by A. Saraby-Reintjes

• Publisher: Elsevier Science
• Year: 1986
• Tongue: English
• Weight: 418 KB
• Volume: 31
• Category: Article
• ISSN: 0013-4686
• DOI: 10.1016/0013-4686(86)87116-x

✦ Synopsis

Additional criteria for distinguishing between the Volmcr-Heyrovsky and the Vohncr-Tafel reaction mechanisms for the hydrogen evolution reaction (HER) have heen derived from a theoretical treatment of polarization curves under conditions of continuous surface renewal From data published by Tomashov and Vershinina for the HER on Pd. Ni, Fe, Sn and Pb, estimates of hydrogen coverages and rate constants have heen made. Approximate values of standard exchange current densities could thus he predicted for the two reaction mechanisms; these have been compared with experimental data. In order to reconcile the various kinetic criteria with each other, it has hem proposed that the Volmer-Heyrovsky reaction mechanism is operative on the majority of metals. Alternative interpretations within the Volmer-Heyrovsky mechanism have heen presented for Tafel slopes in the region of -30 mV dec-t and for the relative positions of volcano curves, which might otherwise have been considered indiitive of the Volmer-Tafel reaction mechanism.