Spectroscopic characterization of chain-to-ring structural evolution in platinum carbide clusters

Abstract

Metal carbides play an important role in catalysis and functional materials. However, the structural characterization of metal carbide clusters has been proven to be a challenging experimental target due to the difficulty in size selection. Here we use the size-specific photoelectron velocity-map imaging spectroscopy to study the structures and properties of platinum carbide clusters. Quantum chemical calculations are carried out to identify the structures and to assign the experimental spectra. The results indicate that the cluster size of the chain-to-ring structural evolution for the PtCn– anions occurs at n = 14, whereas that for the PtCn neutrals at n = 10, revealing a significant effect of charge on the structures of metal carbides. The greatest importance of these building blocks is the strong preference of the Pt atom to expose in the outer side of the chain or ring, exhibiting the active sites for catalyzing potential reactions. These findings provide unique spectroscopic snapshots for the formation and growth of platinum carbide clusters and have important implications in the development of related single-atom catalysts with isolated metal atoms dispersed on supports.