MAGIC CLUSTER IN GRAPHENE CHEMICAL VAPOR DEPOSITION (CVD) GROWTH
Update: 2014-12-30 18:31:51      Author: yangjuan@csrc.ac.cn

CVD is the most promising way to achieve high-quality graphene with macroscopic area at a reasonable price. The nucleation is the most important stage to CVD as it determines both the density of nuclei and the concentration of grain boundaries in the final product. Recently, a type of ultra-stable C clusters were observed on Ru(0001) and Rh(111) surfaces by three astonishing experimental observations [1-3]. Graphene may be achieved by the coarsening of these identical-size ultra-stable C clusters as nuclei. However, due to

the high curvature of the cluster and the influence of metal surfaces, STM was unable to disclose the precise atomic structure of the magic cluster. Therefore, the atomic structure of this C cluster was under highly debate [1-4].

Recently, the debate may be finally resolved by J.-F. Gao and Prof. F. Ding [5], a group of CSRC researchers. As shown in Fig. 1, via first-principles calculations, they disclosed a novel branched C cluster, named C21-3C, which has the core of the aforementioned C21 [4] and three dangling C atoms attached to the three pentagons. C21-3C is exceptional stable and corresponds a local energetic minimum in the size range of 20-30 atoms. Compared with coreshell C21 and other C clusters near its size, the high stability of C21- 3C is attributed to both the stable core and appropriate passivation of dangling C atoms by metal surface. Besides, the relative height and simulated STM images of C21-3C agree the experimental observations well. With many compelling evidences, we confirm C21-3C is the most promising candidate for the observations.

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Further, the relative population of C21-3C is calculated on three metal surfaces, Ru(0001), Rh(111) and Ir(111). Among all C clusters in the size range of 20-30 atoms, the ratio of C21-3C can be as high as 89.1%~99.5% on Ru(0001) and Rh(111) surfaces, while on Ir(111) surface, the ratio of C21-3C is always less than 48.4%, see Fig. 2.

That is, C21-3C can be the dominating on Ru(0001) and Rh(111) surfaces under suitable conditions, but it can’t on Ir(111)-like surfaces. That is why the identical-size ultrastable C cluster can be only observed on Ru(0001) and Rh(111) surfaces in experiments.

 

For more information, please see the paper: “The Structure and Stability of Magic Carbon Clusters Observed in Graphene Chemical Vapor Deposition Growth on Ru(0001) and Rh(111) Surfaces”, Angew. Chem. Int. Ed. 53, 14031 (2014), (Pub. 15 Oct. 2014). DOI: 10.1002/anie.201406570.

 

This research was also supported by Development Fund of CAEP and NSFC.


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