Kinetics of the chemical reduction of platinum-black surface oxides

✍ Scribed by L.D. Burke; A. Moynihan

• Publisher: Elsevier Science
• Year: 1970
• Tongue: English
• Weight: 595 KB
• Volume: 15
• Category: Article
• ISSN: 0013-4686
• DOI: 10.1016/0013-4686(70)80065-2

✦ Synopsis

The rate at which anodic oxide films on platinized platinum electrodes react with hydrogen gas dissolved in aqueous phosphoric acid solution was investigated by measuring-by cathodic stripping techniques-the amount of oxide remaining on the surface after various periods of reaction. The reaction, which was assumed to occur by a purely electrochemical mechanism, was shown to occur at a rate inversely proportional to the oxide coverage. This is interpreted in terms of tbe inhibition of one step of the reaction, namely, the electrochemical oxidation of hydrogen, by adsorbed oxygen species on the surface. The continuous acceleration of the rate of oxide removal over the entire reaction period is assumed to be due to decreasing inhibition with decreasing oxide coverage. A rate equation is derived which gives a linear plot over the entire reaction period. This equation appears to be of general application for the kinetics of this type of process. Rate constants obtained from experiments in the range of 20 to 50°C give an activation energy value of cct 3 kcaljmole.