Communication: Local energetic analysis of the interfacial and surface energies of graphene from the single layer to graphite

Kocherlakota, Lakshmi S.; Krajina, Brad A.; Overney, René M.

doi:10.1063/1.4939248

Cited by 8 publications

(6 citation statements)

References 25 publications

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“…SiO 2 ) in air with =1.47, =3.2·10 15 s −1 , and =4·10 15 s −1 46 , which yields A G ~ 1.52·10 −19 J and is close to reported experimental and theoretical values for HOPG (1.35·10 −19 J in ref. 49); the same theory yields A Au ~ 1.91·10 −19 J for gold (=6.2·10 15 s −1 ). There is no agreement about the influence of the number of graphene sheets on the Hamaker constant yet 46, 49, 50 , but these results suggest the influence to be small.…”

Section: Resultsmentioning

confidence: 71%

“…49); the same theory yields A Au ~ 1.91·10 −19 J for gold (=6.2·10 15 s −1 ). There is no agreement about the influence of the number of graphene sheets on the Hamaker constant yet 46, 49, 50 , but these results suggest the influence to be small. According to mixing rules, the IL is expected to reduce the Hamaker constant with respect to the values obtained in air 39 .…”

Section: Resultsmentioning

confidence: 71%

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Insight into the Electrical Double Layer of an Ionic Liquid on Graphene

Jurado

Espinosa‐Marzal

2017

Sci Rep

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Graphene is a promising next-generation conducting material with the potential to replace traditional electrode materials in supercapacitors. Since energy storage in supercapacitors relies on the electrolyte-electrode interface, here we elucidate the interfacial subnanometer structure of a single component liquid composed solely of cations and anions – an ionic liquid- on electrified graphene. We study the effect of applied potential on the interaction between graphene and a silicon tip in an ionic liquid and describe it within the framework of the Derjaguin-Landau-Verwey-Overbeck (DLVO) theory. The energy is stored in an electrical double layer composed of an extended Stern layer, which consists of multiple ion layers over ~2 nanometers, beyond which a diffuse layer forms to compensate the applied potential on graphene. The electrical double layer significantly responds to the applied potential, and it shows the transition from overscreening to crowding of counterions at the interface at the highest applied potentials. It is proposed that surface charging occurs through the adsorption of the imidazolium cation to unbiased graphene (likely due to π-π interactions) and that the surface potential is better compensated when counterion crowding happens. This study scrutinizes the electrified graphene-ionic liquid interface, with implications not only in the field of energy storage, but also in lubrication.

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Section: Resultsmentioning

confidence: 71%

Section: Resultsmentioning

confidence: 71%

Insight into the Electrical Double Layer of an Ionic Liquid on Graphene

Jurado

Espinosa‐Marzal

2017

Sci Rep

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“…CNTs, graphene, and graphite) in the range of 0.029−0.875 J/m 2 . 66,89,[91][92][93][94][95][96] Higher γ is attributed to carbon deposition in the array with a higher sp 3 carbon character, exhibiting further interactions in addition to the ideal peeling of smooth, well-ordered sp 2 graphitic surfaces with correspondingly lower surface energies. 54,56,96 The calculated γ values also support experimental View Article Online observations, as Raman spectroscopy analysis 69,[97][98][99] of the CNT base after array pull-off (see Section S4 of the Supporting Information) shows that the CNTs exhibit a well-ordered, sp 2 graphitic wall structure in Mode I, and a more defective, turbostratic sp 3 carbon structure in Mode II as carbon deposits on the outer CNT walls at long t p .…”

Section: Cnt-substrate Adhesion: Experimental and Modeling Resultsmentioning

confidence: 99%

Substrate adhesion evolves non-monotonically with processing time in millimeter-scale aligned carbon nanotube arrays

et al. 2021

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“…Two dimensional (2D) metal cluster formation is thermodynamically favored when γ support is large; γ metal is small; and the metal–substrate interaction is strong . In the case of Sn on HOPG, only the low γ Sn (0.5 J/m 2 ) favors 2D growth, whereas the weak Sn–HOPG interactions and γ HOPG (0.14–0.15 J/m 2 ) do not. Although γ Sn is larger than γ HOPG , entropy favors the formation of small 2D Sn clusters over aggregation into large 3D clusters at low coverages.…”

Section: Discussionmentioning

confidence: 99%

Growth of Uniquely Small Tin Clusters on Highly Oriented Pyrolytic Graphite

Beniwal,

Chai,

Qiao

et al. 2024

J. Phys. Chem. C

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Sn clusters have been grown on highly oriented pyrolytic graphite (HOPG) surfaces and investigated by scanning tunneling microscopy (STM), X-ray photoelectron spectroscopy (XPS), and density functional theory (DFT) calculations. At low Sn coverages ranging from 0.02 to 0.25 ML, Sn grows as small clusters that nucleate uniformly on the terraces. This behavior is in contrast with the growth of transition metals such as Pd, Pt, and Re on HOPG, given that these metals form large clusters with preferential nucleation for Pd and Pt at the favored low-coordination step edges. XPS experiments show no evidence of Sn−HOPG interactions, and the activation energy barrier for diffusion calculated for Sn on HOPG (0.06 eV) is lower or comparable to those of Pd, Pt, and Re (0.04, 0.22, and 0.61 eV, respectively), indicating that the growth of the Sn clusters is not kinetically limited by diffusion on the surface. DFT calculations of the binding energy/atom as a function of cluster size demonstrate that the energies of the Sn clusters on HOPG are similar to those of Sn atoms in the bulk for Sn clusters larger than 10 atoms, whereas the Pt, Pd, and Re clusters on HOPG have energies that are 1−2 eV higher than in the bulk. Thus, there is no thermodynamic driving force for Sn atoms to form clusters larger than 10 atoms on HOPG, unlike for Pd, Pt, and Re atoms, which minimize their energy by aggregating into larger, more bulk-like clusters. In addition, annealing the Sn/HOPG clusters to 800 and 950 K does not increase the cluster size, but instead removes the larger clusters, while Sn deposition at 810 K induces the appearance of protrusions that are believed to be from subsurface Sn. DFT studies indicate that it is energetically favorable for a Sn atom to exist in the subsurface layer only when it is located at a subsurface vacancy.

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Communication: Local energetic analysis of the interfacial and surface energies of graphene from the single layer to graphite

Cited by 8 publications

References 25 publications

Insight into the Electrical Double Layer of an Ionic Liquid on Graphene

Insight into the Electrical Double Layer of an Ionic Liquid on Graphene

Substrate adhesion evolves non-monotonically with processing time in millimeter-scale aligned carbon nanotube arrays

Growth of Uniquely Small Tin Clusters on Highly Oriented Pyrolytic Graphite

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