Accession Number:

AD0672360

Title:

HYDROGEN OVERPOTENTIAL ON PLATINUM.

Descriptive Note:

Technical rept.,

Corporate Author:

CASE-WESTERN RESERVE UNIV CLEVELAND OHIO ELECTROCHEMISTRY RESEARCH LAB

Personal Author(s):

• Ludwig,Frank A.
• Yeager,Ernest

Report Date:

1968-02-01

Pagination or Media Count:

276.0

Abstract:

Hydrogen electrode kinetics have been examined in Pt in HCl solutions over a large range of anodic and cathodic current densities using several techniques rotating disc-ring, cyclic linear sweep voltammetry, interrupter, and pulse techniques. Bubble formation was studied on the rotating disc electrode photographically. The experimental results support the following conclusions 1 Under most anodic and cathodic conditions in concentrated acids, the hydrogen electrode on Pt is under combined H2-diffusion and kinetic control. 2 Both the discharge and oxidation of H2 on Pt proceed through the combination mechanism with the atomic-combination step rate controlling. Two types of absorbed hydrogen appear to be involved--one strong at high coverage and one weak at lower coverage. Thus M- H e- M-HA MHA M-HB 2M-HB M- H2 where M-HA is the more strongly bound hydrogen. 3 In well purified solutions, extreme supersaturation with dissolved H2 occurs during cathodic polarization at high currents densities. 4 Theoretical considerations reveal that the transfer coefficient or its equivalent for the recombination and ion-plus-atom steps are probably closer to unity than the usual value of 12. Author

Descriptors:

• (*HYDROGEN
• ELECTROCHEMISTRY)
• (*ELECTRODES
• REACTION KINETICS)
• PLATINUM
• HYDROCHLORIC ACID
• OXIDATION REDUCTION REACTIONS
• BUBBLES
• ABSORPTION
• TRANSIENTS

Subject Categories:

• Physical Chemistry

Distribution Statement:

APPROVED FOR PUBLIC RELEASE