H/D exchange reaction on mono-disperse Pt clusters: enhanced activity from minute O concentrations

The H 2 /D 2 exchange reaction was studied on mono-disperse Pt 8 clusters in a μ-reactor. The chemical activity was studied at temperatures varying from room temperature to 180 °C using mass spectrometry. It was found that minute amounts of O 2 in the gas stream increased the chemical activity significantly. XPS and ISS before and after reaction suggest little or no sintering during reaction. A reaction pathway is suggested based on DFT. H 2 desorption is identified as the rate-limiting step and O 2 is confirmed as the source of the increased activity. The binding energy of platinum atoms in a SiO 2 supported Pt 8 cluster is found to be comparable to the interatomic binding energies of bulk platinum, underlining the stability of the model system. Hydrogen dissociation on mono-disperse platinum clusters is found to increase with minute amounts of oxygen in the gas stream.