Experimental and theoretical studies of the atomic structure of platinum-based nanoclusters

[摘要] This thesis focuses on the atomic structure of Platinum-based nanoclusters, and covers two main areas: Binary platinum-titanium clusters, and pure platinum clusters. Both were produced with a magnetron sputtering, gas-aggregation cluster beam source, and imaged with a Scanning Transmission Electron Microscope (STEM) with detailed image analysis. For the study of Pt-Ti clusters, identifying their overall morphology is key. For oxidised clusters, a Pt core with a TiOx shell is found for smaller clusters, whereas for larger clusters multiple Pt cores are seen within the TiOx shell. The Pt-Ti clusters have been transferred under nitrogen, to reduce oxidation. Here, the morphology of the clusters is more amorphous, with the Pt and Ti atoms forming an alloy core within the cluster. Experimentally, clusters were produced containing 10- 600 Pt atoms. The structural motif of these clusters shows that the large clusters (> 250 Pt atoms) typically present with a cubic structure which matches that of bulk FCC Pt. This experimental work has been complemented by theoretical modeling, to identify dominant motifs within a large size range from 55 - 10,000 Pt atoms, using empirical potentials. The results show that there is a persistent switching between the decahedral and octahedral motifs.

[发布机构] University:University of Birmingham;Department:School of Chemical Engineering

[关键词] T Technology;TP Chemical technology