Challenges in Determining Structure of Supported Subnano Metal Clusters

Subnano metal clusters exhibit unique optical, catalytic, electronic and magnetic properties that are not observed in their corresponding bulk counterparts. Such distinct behaviors of metal clusters can be attributed to many factors including quantum confinement, high surface-to-bulk atom ratio, and their unique size-and configuration-dependent electronic shell structures. Supported subnano clusters are of particular interest in catalysis since small changes in atomicity, composition, and/or even their geometric configuration can significantly influence their catalytic activity and selectivity [1-2]. Supported metal clusters at the single atom limit have yielded excellent performance for catalytic transformation of a variety of important molecules [3]. Strong metal-support interactions become dominant for supported subnano clusters or single atoms [3][4][5]. A major obstacle to gaining a deeper understanding of catalysis by supported clusters is the lack of information on their geometric configurations and electronic structures.