Blurring the boundary between homogenous and heterogeneous catalysis using palladium nanoclusters with dynamic surfaces

• Published in: Nature communications Vol. 12; no. 1; p. 4965
• Main Authors: Cano, Israel, Weilhard, Andreas, Martin, Carmen, Pinto, Jose, Lodge, Rhys W., Santos, Ana R., Rance, Graham A., Åhlgren, Elina Harriet, Jónsson, Erlendur, Yuan, Jun, Li, Ziyou Y., Licence, Peter, Khlobystov, Andrei N., Alves Fernandes, Jesum
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group UK 17-08-2021; Nature Publishing Group; Nature Portfolio
• Subjects: 140/133; 140/146; 140/58; 147/137; 147/143; 147/28; 639/638/77/884; 639/638/77/885; 639/638/77/887; Alkenes; Blurring; Catalysis; Catalysts; Catalytic activity; Diffusion; Humanities and Social Sciences; Ionic liquids; Magnetron sputtering; Mercury; multidisciplinary; Nanoclusters; Palladium; Science; Science (multidisciplinary)
• DOI: 10.1038/s41467-021-25263-6
• EISSN: 2041-1723

Using a magnetron sputtering approach that allows size-controlled formation of nanoclusters, we have created palladium nanoclusters that combine the features of both heterogeneous and homogeneous catalysts. Here we report the atomic structures and electronic environments of a series of metal nanoclusters in ionic liquids at different stages of formation, leading to the discovery of Pd nanoclusters with a core of
ca
. 2 nm surrounded by a diffuse dynamic shell of atoms in [C
4
C
1
Im][NTf
2
]. Comparison of the catalytic activity of Pd nanoclusters in alkene cyclopropanation reveals that the atomically dynamic surface is critically important, increasing the activity by a factor of
ca
. 2 when compared to compact nanoclusters of similar size. Catalyst poisoning tests using mercury and dibenzo[
a,e
]cyclooctene show that dynamic Pd nanoclusters maintain their catalytic activity, which demonstrate their combined features of homogeneous and heterogeneous catalysts within the same material. Additionally, kinetic studies of cyclopropanation of alkenes mediated by the dynamic Pd nanoclusters reveal an observed catalyst order of 1, underpinning the pseudo-homogeneous character of the dynamic Pd nanoclusters.
Establishing a structure-property relationship for nanoclusters and the link with their catalytic performance remain challenging. Here the authors show palladium nanocluster with a core of 2 nm surrounded by a diffuse dynamic shell of Pd atoms exhibit features of heterogeneous and homogenous catalyst at the same time.