Nanocatalysis Staying put

Vajda and colleagues report on the preparation of size-selected Pt 8-10 clusters stabilized on a high-surface-area aluminum oxide film prepared by atomic layer deposition. Studies performed on gas-phase mass-selected metal clusters reveal that below a given size, typically a few tens of atoms, one enters a non-scalable regime where the properties of the particle change markedly with size. The researchers have produced gas-phase neutral and positively charged platinum clusters using a laser vaporization source, the positively charged clusters are guided into a quadrupole mass spectrometer, and selected according to mass. Characterization of the samples is provided by synchrotron X-ray scattering measurements that show the stability and the three-dimensional shape of the platinum clusters. The work of Vajda and collaborators represents an important example of catalytic activity of mass-selected metal clusters under realistic conditions of temperature and pressure.