Platinum Metals Review - Volume 22, Issue 4, 1978

Co-ordination complexes of ruthenium and rhodium have been shown to have potential applications in solar energy conversion. When illuminated with visible light on a laboratory scale these complexes catalyse photolysis reactions or exhibit photogalvanic effects to produce hydrogen or electricity. These processes and the problems involved in their immediate scale-up to practical solar energy conversion devices are discussed in this paper.

Iridium is generally considered to be a less effective catalyst than the other platinum metals but when highly co-ordinatively unsaturated species of it are prepared they appear to be exceptionally active hydrogenation catalysts, even for reduction of sterically hindered olefins. A mechanism for this reaction has been postulated based on low temperature magnetic resonance evidence. As the reaction proceeds, catalytically inactive hydrogen bridged cluster compounds are formed but work is in progress to counter this deactivation by physically separating the catalytic centres on a polymer support.

At a four-day conference held at Zürich in August 1978 one hundred and fifty-nine papers were presented covering many facets of a potential hydrogen economy. The platinum group metals are already utilised in several aspects of hydrogen production and use. From this brief review of some of the relevant papers presented it seems probable that they will continue to play an important role.

During hydrogen cyanide production by the Andrussow process considerable redistribution of the surface of the rhodium-platinum gauze catalyst occurs, resulting in the formation of a porous mass of well-faceted metal crystallites. The phenomenon is illustrated in this paper, and some possible mechanisms to account for its formation are discussed.

The early researches on platinum carried out by a number of distinguished European chemists were virtually contemporary with the first scientific studies of porcelain and its decoration. The author traces the sequence of these investigations leading to the application of platinum to provide a brilliant and permanent metallic lustre to porcelain and later to the less expensive earthenware.