Magic Number Pt₁₃ and Misshapen Pt₁₂ Clusters: Which One is the Better Catalyst?

Abstract

A relationship between the size of metal particles and their catalytic activity has been established over a nanometer scale (2-10 nm). However, application on a subnanometer scale (0.5-2 nm) is difficult, a possible reason being that the activity no longer relies on the size but rather the geometric structure as a cluster (or superatomic) compound. We now report that the catalytic activity for the oxygen reduction reaction (ORR) significantly increased when only one atom was removed from a magic number cluster composed of 13-platinum atoms (Pt13). The synthesis with an atomic-level precision was successfully achieved by using a dendrimer ligand as the macromolecular template strictly defining the number of metal atoms. It was quite surprising that the Pt12 cluster exhibited more than 2-fold catalytic activity compared with that of the Pt13 cluster. ESI-TOF-mass and EXAFS analyses provided information about the structures. These analyses suggested that the Pt12 has a deformed coordination, while the Pt13 has a well-known icosahedral atomic coordination as part of the stable cluster series. Theoretical analyses based on density functional theory (DFT) also supported this idea. The present results suggest potential activity of the metastable clusters although they have been "missing" species in conventional statistical synthesis.

High stability and reactivity of defective graphene-supported Fe n Pt13−n (n = 1, 2, and 3) nanoparticles for oxygen reduction reaction: a theoretical study

“…1 and the corresponding cohesive energetics, magnetics properties, and charge transfer between Fe and Pt are summarized in Table 1. Interestingly, the catalytic activity for the ORR can increase 2.5 times when only one Pt atom was removed from a magic number cluster (Pt 13 ) as reported in a recent study (Imaoka et al 2013).…”

Coordination Programming: A New Concept for the Creation of Multifunctional Molecular Systems

“…29 Its self-assembly was affected by the absence and presence of KPF 6 or La(OTf) 3 : when monovalent KPF 6 was added, the expected octamer formed without showing any Au(I)Au(I) interactions, while in the presence of trivalent La(OTf) 3 a more closely stacked octamer was obtained, leading to Au(I)Au(I) interactions. Horie, Osakada, and co-workers presented a pseudorotaxane consisting of dibenzo [24]crown-8 (DB24C8) and (N-xylylammonio)methylferrocene as the respective cyclic and axle component molecules. The system acted as a thermally driven molecular switch in the single-crystal state.…”

Effect of the Core Structure on the Sequential Coordination of Phenylazomethine Dendrimer

“…The characteristic point of DPA is that the coordination to Lewis acids occur in a stepwise radial fashion from the inner layer to the outer layer which is useful as a atomnumber specified sub-nanometer metalcluster template [41][42][43][44]. This sequential coordination is caused by the spontaneously expressed electron density gradient of the coordination site (nitrogen atom), and this gradient can be also used as a molecular rectifier [45].…”