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
School of Chemistry, University of Nottingham, Nottingham, UK.
GSK Carbon Neutral Laboratories for Sustainable Chemistry, University of Nottingham, Nottingham, UK.
Nat Commun. 2021 Aug 17;12(1):4965. doi: 10.1038/s41467-021-25263-6.
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 [CCIm][NTf]. 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.
我们采用磁控溅射法制备了尺寸可控的纳米团簇，成功合成了兼具多相催化剂和均相催化剂特性的钯纳米团簇。在此，我们报道了一系列金属纳米团簇在离子液体中不同形成阶段的原子结构和电子环境，发现了一种钯纳米团簇，其在[CCIm][NTf]中具有约2nm的核心，周围环绕着一层扩散的动态原子壳。对钯纳米团簇在烯烃环丙烷化反应中的催化活性进行比较后发现，原子动态表面至关重要，与类似尺寸的致密纳米团簇相比，其活性提高了约2倍。使用汞和二苯并[a,e]环辛烯进行的催化剂中毒测试表明，动态钯纳米团簇保持了其催化活性，这证明了它们在同一材料中兼具均相催化剂和多相催化剂的特性。此外，对由动态钯纳米团簇介导的烯烃环丙烷化反应的动力学研究表明，观察到的催化剂级数为1，这支持了动态钯纳米团簇的准均相性质。
