Studies on the mechanism of the hydrogen electrode reaction by means of deuterium tracer—II. The reaction mechanism

✍ Scribed by T. Matsushima; M. Enyo

• Publisher: Elsevier Science
• Year: 1974
• Tongue: English
• Weight: 580 KB
• Volume: 19
• Category: Article
• ISSN: 0013-4686
• DOI: 10.1016/0013-4686(74)80029-0

✦ Synopsis

The exchange reaction bctwccn deuterium gas and light water was conducted with Ni, Rh, and Pt catalyst. Through analysis of isotopic composition of the gaseous hydrogen during the exchange reaction, the exchange rates of the individual steps, H2 s 2H(a) and H(a) + B Z+ H+B + r, of the hydrogen electrode reaction were determined at various hydrogen pressures and solution pH's, where H(a) is a hydrogen adatom and B = HZ0 or OH-. The rates of the steps wcrc widely different among the metals studied but, throughout

these metals, the hydrogen pressure dependence of the rate of the first step was with the power of lGO.9, and that of the second step, 0.245.

Both the rates were independent of solution pH. Generally, the former step is virtually rate-determining under low hydrogen pressures, whereas the latter takes over the role with increasing hydrogen pressure. Under ordinary pressures, the first step is virtually rate-determining on Pt but qeither step is singly rate-determining on Rh and Ni.