Pt and Rh nanoclusters, grown on deposition of Pt and Rh vapors onto graphene/Pt(111), show separate reactivity toward the decomposition of methanol-d4. The Pt (Rh) clusters had a mean diameter 2.0–3.5 nm (2.1–4.0 nm) and height 0.45–0.94 nm (0.41–0.9 nm) evolving with the coverage; they were structurally ordered, having an fcc phase and growing in (111) orientation, and had lattice constants similar to their bulk values. Methanol-d4 on the Pt clusters did not decompose but desorbed mostly, disparate from that on Pt(111) surface; the disparity arose as the adsorption energies of methanol-d4 on most surface sites of the Pt clusters became smaller than their single crystal counterpart. This size effect, nevertheless, did not apply on the Rh clusters, despite their similar atomic stacking; the Rh clusters showed a reactivity similar to that of the Rh(111) surface because the adsorption energies of methanol-d4 on both Rh clusters and Rh(111) are comparable. The distinct size dependence was rationalized through their electronic structures and charge distribution of Fukui function mapping. Our results suggest that reactive transition metals do not necessarily become more reactive while they are scaled down to nanoscale; their reactivity evolves with their size in a manner largely dependent on their electronic nature.
Atomic structures of Pt nanoclusters on graphene/Pt(111) were investigated with various techniques to probe the surface under ultrahighvacuum conditions and with calculations based on density-functional theory. Monolayer graphene was grown on thermal decomposition of ethylene on Pt(111) at 950 K and Pt clusters on the deposition of Pt vapor onto graphene/ Pt(111) at 300 K. The graphene had two predominant domains: one had a small angle of rotation between the graphene and the underlying Pt lattice, structurally commensurate with the Pt( 111) lattice (G 0°) , and the other was rotated about 30°with respect to the Pt lattice (G 30°) . G 0°h ad a slightly corrugated structure, involving tetrahedral hybridization, and a stronger adsorption on Pt(111); in contrast, G 30°w as flat and weakly bound to Pt(111) via a van der Waals interaction. The grown Pt clusters were structurally ordered, having a face-centered cubic phase and growing in a (111) orientation, whereas they had correspondingly disparate nucleation modes and rotational configurations on the two major graphene domains. On G 0°, the clusters were smaller and had a narrow size distribution and greater cluster density; they were structurally commensurate with the G 0°l attice (with their [−110] (or [0− 11]) axes along direction [1−100] of G 0°) . In contrast, on G 30°, the clusters were larger and had an evidently broader size distribution and smaller cluster density; they preferred to rotate by 30°relative to the underlying G 30°l attice. The former is attributed to a strong Pt−G 0°i nteraction, whereas the latter is only partly attributed to a weak Pt−G 30°i nteraction; the preferential rotation of Pt clusters on G 30°i s governed not only by the graphene lattice, but largely by an indirect interaction between the Pt substrate and the clusters, likely through the charge transferred from the Pt substrate to graphene.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.