Spatially Resolved Raman Spectroscopy of Carbon Electrode Surfaces:  Observations of Structural and Chemical Heterogeneity

Ray, Kenneth G.; McCreery, Richard L.

doi:10.1021/ac9705531

Cited by 146 publications

(132 citation statements)

References 36 publications

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“…These results are consistent with experiments which have shown that the yield of the electrografting reaction is significantly greater on GC than on basal plane graphite [10] and faster at edge plane graphite than at the basal plane [37], although it is not clear whether electrografting at basal plane graphite occurs at pristine graphene sheets or only at defect sites. Hence both theory and experiment support the conclusion that strong covalent bonds can be formed between aryl groups and the edge plane of graphitic carbons, but the mechanism of bond formation remains to be elucidated.…”

Section: Grafting Using Aryldiazonium Saltssupporting

confidence: 87%

Covalent modification of graphitic carbon substrates by non-electrochemical methods

Barrière

Downard

2008

J Solid State Electrochem

157

119

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Abstract:New methods for modifying graphitic carbon surfaces without electrochemical assistance, and without the deliberate formation of carbon surface oxygen functionalities, have emerged in the past decade. The approaches rely on spontaneous reactions of aryldiazonium salts, primary amines, ammonia and iodine azide at room temperature, chemical reduction of aryldiazonium salts, reactions of alkenes and alkynes at elevated temperatures, and photochemical reactions of alkenes, alkynes, azides and diazirines. This review describes the methodology and scope of these reactions at graphitic carbon materials (excluding carbon nanotubes), examines mechanistic possibilities and future prospects.

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Section: Grafting Using Aryldiazonium Saltssupporting

confidence: 87%

Covalent modification of graphitic carbon substrates by non-electrochemical methods

Barrière

Downard

2008

J Solid State Electrochem

157

119

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“…Making extensive use of high resolution microscopy to understand the surface characteristics of HOPG, the studies reported herein provide a new and self-consistent view of the electroactivity, tying together macroscale, microscale and nanoscale measurements. Our results show unequivocally that the pristine HOPG surface, which has been variously described as supporting only sluggish ET behavior,[20][21][22]35,41,49 or even as being completely inert, 8f,g,9,17,24,50 has, in fact, considerable ET activity. 4-/3-voltammetry was selected as a means for 'surface validation' 8a-e of HOPG for the subsequent study of further redox couples whose ET kinetics may have been impaired, and that it has been used extensively as a redox probe to assess ET activity at the basal surface of HOPG.…”

Section: Discussionsupporting

confidence: 59%

A New View of Electrochemistry at Highly Oriented Pyrolytic Graphite

et al. 2012

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Major new insights on electrochemical processes at graphite electrodes are reported, following extensive investigations of two of the most studied redox couples, Fe(CN) 6 4−/3− and Ru(NH 3 ) 6 3+/2+ . Experiments have been carried out on five different grades of highly oriented pyrolytic graphite (HOPG) that vary in step-edge height and surface coverage. Significantly, the same electrochemical characteristic is observed on all surfaces, independent of surface quality: initial cyclic voltammetry (CV) is close to reversible on freshly cleaved surfaces (>400 measurements for Fe(CN) 6 4−/3− and >100 for Ru(NH 3 ) 6 3+/2+ ), in marked contrast to previous studies that have found very slow electron transfer (ET) kinetics, with an interpretation that ET only occurs at step edges. Significantly, high spatial resolution electrochemical imaging with scanning electrochemical cell microscopy, on the highest quality mechanically cleaved HOPG, demonstrates definitively that the pristine basal surface supports fast ET, and that ET is not confined to step edges. However, the history of the HOPG surface strongly influences the electrochemical behavior. Thus, Fe(CN) 6 4−/3− shows markedly diminished ET kinetics with either extended exposure of the HOPG surface to the ambient environment or repeated CV measurements. In situ atomic force microscopy (AFM) reveals that the deterioration in apparent ET kinetics is coupled with the deposition of material on the HOPG electrode, while conducting-AFM highlights that, after cleaving, the local surface conductivity of HOPG deteriorates significantly with time. These observations and new insights are not only important for graphite, but have significant implications for electrochemistry at related carbon materials such as graphene and carbon nanotubes.

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“…49 Surface Raman spectroscopy, 50 as well as theoretical predictions 51 indicate more rapid bonding at edge sites over basal sites in either ordered graphite or graphene sheets. Although the precise geometry of attachment on the disordered PPF surface is difficult to determine, we will assume edge-bonding to graphitic planes during surface modification.…”

Section: ■ Results and Discussionmentioning

confidence: 93%

Theoretical Modeling of Tunneling Barriers in Carbon-Based Molecular Electronic Junctions

et al. 2015

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Vous avez des questions? Nous pouvons vous aider. Pour communiquer directement avec un auteur, consultez la première page de la revue dans laquelle son article a été publié afin de trouver ses coordonnées. Si vous n'arrivez pas à les repérer, communiquez avec nous à PublicationsArchive-ArchivesPublications@nrc-cnrc.gc.ca. Questions? Contact the NRC Publications Archive team atPublicationsArchive-ArchivesPublications@nrc-cnrc.gc.ca. If you wish to email the authors directly, please see the first page of the publication for their contact information. NRC Publications Archive Archives des publications du CNRCThis publication could be one of several versions: author's original, accepted manuscript or the publisher's version. / La version de cette publication peut être l'une des suivantes : la version prépublication de l'auteur, la version acceptée du manuscrit ou la version de l'éditeur. For the publisher's version, please access the DOI link below./ Pour consulter la version de l'éditeur, utilisez le lien DOI ci-dessous.http://doi.org/10.1021/jp5128332Access and use of this website and the material on it are subject to the Terms and Conditions set forth at Theoretical modeling of tunneling barriers in carbon-based molecular electronic junctions Kondratenko, Mykola; Stoyanov, Stanislav R.; Gusarov, Sergey; Kovalenko, Andriy; Mccreery, Richard L.http://nparc.cisti-icist.nrc-cnrc.gc.ca/fra/droits L'accès à ce site Web et l'utilisation de son contenu sont assujettis aux conditions présentées dans le site LISEZ CES CONDITIONS ATTENTIVEMENT AVANT D'UTILISER CE SITE WEB. NRC Publications Record / Notice d'Archives des publications de CNRC:http://nparc.cisti-icist.nrc-cnrc.gc.ca/eng/view/object/?id=8518ba31-e362-42a1-9e60-e323168de949 http://nparc.cisti-icist.nrc-cnrc.gc.ca/fra/voir/objet/?id=8518ba31-e362-42a1-9e60-e323168de949 ABSTRACT: Density functional theory (DFT) is applied to three models for carbon-based molecular junctions containing fragments of graphene with covalent edge-bonding to aromatic and aliphatic molecules, with the graphene representing a sp 2 hybridized carbon electrode and the molecule representing a molecular layer between two electrodes. The DFT results agree well with experimental work functions and transport barriers, including the electronic coupling between molecular layers and graphitic contacts, and predict the compression of tunnel barriers observed for both ultraviolet photoelectron spectroscopy (UPS) and experimental tunneling currents. The results reveal the strong effect of the dihedral angle between the planes of the graphene electrode and the aromatic molecule and imply that the molecules with the smallest dihedral angle are responsible for the largest local current densities. In addition, the results are consistent with the proposal that the orbitals which mediate tunneling are those with significant electron density in the molecular layer. These conclusions should prove valuable for understanding the relationships between molecular structure and electronic transport as an important ...

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Spatially Resolved Raman Spectroscopy of Carbon Electrode Surfaces: Observations of Structural and Chemical Heterogeneity

Cited by 146 publications

References 36 publications

Covalent modification of graphitic carbon substrates by non-electrochemical methods

Covalent modification of graphitic carbon substrates by non-electrochemical methods

A New View of Electrochemistry at Highly Oriented Pyrolytic Graphite

Theoretical Modeling of Tunneling Barriers in Carbon-Based Molecular Electronic Junctions

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