Transition metals on the (0 0 0 1) surface of graphite: Fundamental aspects of adsorption, diffusion, and morphology

Abstract

In this article, we review basic information about the interaction of transition metal atoms with the (0001) surface of graphite, especially fundamental phenomena related to growth. Those phenomena involve adatomsurface bonding, diffusion, morphology of metal clusters, interactions with steps and sputter-induced defects, condensation, and desorption. General traits emerge which have not been summarized previously. Some of these features are rather surprising when compared with metal-on-metal adsorption and growth. Opportunities for future work are pointed out. Chemistry | Materials Science and Engineering | PhysicsComments NOTICE: This is the author's version of a work that was accepted for publication in Progress in Surface Science. Changes resulting from the publishing process, such as peer review, editing, corrections, structural formatting, and other quality control mechanisms may not be reflected in this document. Changes may have been made to this work since it was submitted for publications. A definitive version was subsequently published in Progress in Surface Science, 89 (2014), doi: 10.1016/j.progsurf.2014.08.001. AuthorsDavid Victor Appy, Huaping Lei, Cai-Zhuang Wang, Michael C. Tringides, Da-Jiang Liu, James W. Evans, and Patricia A. Thiel This article is available at Iowa State University Digital Repository: http://lib.dr.iastate.edu/chem_pubs/99 1 NOTICE: This is the author's version of a work that was accepted for publication in Progress in Surface Science. Changes resulting from the publishing process, such as peer review, editing, corrections, structural formatting, and other quality control mechanisms may not be reflected in this document. Changes may have been made to this work since it was submitted for publications. A definitive version was subsequently published in Progress in Surface Science, 89 (2014) Abstract.In this article, we review basic information about the interaction of transition metal atoms with the (0001) surface of graphite, especially fundamental phenomena related to growth. Those phenomena involve adatom-surface bonding, diffusion, morphology of metal clusters, interactions with steps and sputter-induced defects, condensation, and desorption. General traits emerge which have not been summarized previously. Some of these features are rather surprising when compared with metal-onmetal adsorption and growth. Opportunities for future work are pointed out. 1.Introduction.Graphite is an intriguing support for metals because of its inertness in aggressive environments, as well as its low cost and high abundance. A major application for graphite-supported metals is lithium ion batteries [1,2]. In fact, the demand for these batteries is expanding so quickly that it currently drives the international market in graphite [1]. An important application on the horizon is biofuel conversion, where graphite (or other carbon-based materials) may provide robust supports for catalysts in aqueous media [3].Adsorption of transition metals and noble metals on graphite has been studi...

Determining whether metals nucleate homogeneously on graphite: A case study with copper

“…As in our study of Cu/HOPG, analyses of N(θ) and the ISD can be powerful tools for identifying the correct model. We conclude that metal cluster growth on smooth graphite terraces-a simple and common observation in the literature [6] -must be interpreted with care, certainly for graphite and possibly for other carbon-rich surfaces as well.…”

“…It is noteworthy that our calculations incorporate the dispersion forces that bind the carbon sheets in graphite. DFT shows that a Cu atom adsorbs atop a C atom with no C atom in the layer beneath (the graphite β site [6]), and the adsorption energy (E ads ) is 0.589 eV. A Cu atom diffuses between β sites along C-C bonds, with an associated energy barrier (E diff ) of 0.020 eV.…”

“…There have been many studies of model systems, especially studies of transition metals on graphite. [6] In these studies, it has been very common to observe clusters of metals on the (0001) terraces of graphite [6]. However, only rarely have the clusters' characteristics been analyzed in relation to the mechanism or energetics of homogeneous nucleation and…”

Formation and morphological evolution of self-similar 3D nanostructures on weakly interacting substrates

“…Following the early categorization and description of 3D (Volmer-Weber) film growth by Bauer [31], recent studies of metal-film and nanostructure growth on graphite [32], graphene [4], and other 2D materials [5,6] have explained experimentally observed growth morphologies as a function of the ratio between the adsorption energy (E ads ) of metal atoms on the substrate and the bulk-metal cohesive energy (E coh ); the lower the E ads /E coh ratio, the stronger the tendency toward 3D growth. Intuitively, this can be understood as the metal atoms being more weakly bound to the substrate, which facilitates their ascent onto the first layer of an island by either direct hopping or an exchange mechanism [33].…”

“…These facets have been suggested to facilitate growth of AlSn alloy films on weakly interacting substratesincluding amorphous-C, SiO 2 , NaCl, and mica [3,[45][46][47]-by providing pathways for accelerated mass transport between the base and the upper layer of 3D atomic islands. Moreover, facet formation has been experimentally observed during the deposition of metal films on graphene and graphite surfaces [4,32]. Hence, in the context of 3D growth beyond the second layer, the absence of steps may allow adatoms to ascend multiple layers by encountering a terrace diffusion barrier [E s in Fig.…”