Kinetic study of the reduction of water to hydrogen by reduced methyl viologen mediated by platinised alumina
- 1 January 1990
- journal article
- research article
- Published by Royal Society of Chemistry (RSC) in Journal of the Chemical Society, Faraday Transactions
- Vol. 86 (9) , 1417-1423
- https://doi.org/10.1039/ft9908601417
Abstract
The reduction of water to H2 by reduced methyl viologen, MV˙+, mediated by a number of different redox catalysts has been studied via the oxidation of MV˙+ and concomitant generation of H2. One of the best catalysts found, in terms of H2 evolution efficiency, activity, reproducibility and stability, is an H2-pretreated sample of platinised alumina (Pt–Al2O3) which gave H2 yields of ca. 75%. The kinetics of H2O reduction by MV˙+, mediated by this catalyst have been studied as a function of pH and from the results it appeared there was a diffusion-controlled region (at pH < 3.1) and an activation-controlled region (at pH > 4). The kinetics of MV˙+ oxidation were studied in these two regions as a function of [MV˙+], [MV2+], [cat] and temperature, and the results interpreted in terms of an electrochemical model of redox catalysis in which a Nernstian oxidation reaction (i.e. MV˙+–e–→ MV2+) is coupled to an irreversible reduction reaction (i.e. H++ e–→½H2)via electron transfer through the Pt particles on the alumina support.Keywords
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