Nanocrystalline gold and gold-palladium alloy oxidation catalysts: a personal reflection on the nature of the active sites

The discoveries that supported gold nanoparticles are exceptionally efficient catalysts for a whole range of reactions is one of the most surprising revelations in the recent history of chemistry. For many years gold was considered too noble to be chemically interesting. However, when divided to the nano-scale, small gold nanoparticles comprising relatively few atoms, are very efficient in catalysing a range of redox and chemical synthesis reactions. In this perspectives article some of the recent research in this rapidly evolving field is highlighted, and the nature of the active site for oxidation reactions is commented on.