Zhang, Guohui, Kirkman, Paul M., Patel, Anisha N., Cuharuc, Anatolii S., McKelvey, Kim M. (Kim Martin) and Unwin, Patrick R. (2014) Molecular functionalization of graphite surfaces : Basal Plane versus Step Edge electrochemical activity. Journal of the American Chemical Society, Volume 136 (Number 32). pp. 11444-11451. doi:10.1021/ja505266d

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Abstract

The chemical functionalization of carbon surfaces has myriad applications, from tailored sensors to electrocatalysts. Here, the adsorption and electrochemistry of anthraquinone-2,6-disulfonate (AQDS) is studied on highly oriented pyrolytic graphite (HOPG) as a model sp2 surface. A major focus is to elucidate whether adsorbed electroactive AQDS can be used as a marker of step edges, which have generally been regarded as the main electroactive sites on graphite electrode surfaces. First, the macroscopic electrochemistry of AQDS is studied on a range of surfaces differing in step edge density by more than 2 orders of magnitude, complemented with ex situ tapping mode atomic force microscopy (AFM) data. These measurements show that step edges have little effect on the extent of adsorbed electroactive AQDS. Second, a new fast scan cyclic voltammetry protocol carried out with scanning electrochemical cell microscopy (SECCM) enables the evolution of AQDS adsorption to be followed locally on a rapid time scale. Subsequent AFM imaging of the areas probed by SECCM allows a direct correlation of the electroactive adsorption coverage and the actual step edge density of the entire working area. The amount of adsorbed electroactive AQDS and the electron transfer kinetics are independent of the step edge coverage. Last, SECCM reactive patterning is carried out with complementary AFM measurements to probe the diffusional electroactivity of AQDS. There is essentially uniform and high activity across the basal surface of HOPG. This work provides new methodology to monitor adsorption processes at surfaces and shows unambiguously that there is no correlation between the step edge density of graphite surfaces and the observed coverage of electroactive AQDS. The electroactivity is dominated by the basal surface, and studies that have used AQDS as a marker of steps need to be revised.

Item Type:	Journal Article
Subjects:	Q Science > QD Chemistry
Divisions:	Faculty of Science > Chemistry
Library of Congress Subject Headings (LCSH):	Graphite, Nanostructured materials, Surface chemistry
Journal or Publication Title:	Journal of the American Chemical Society
Publisher:	American Chemical Society
ISSN:	0002-7863
Official Date:	13 August 2014
Dates:	Date Event 13 August 2014 Published 1 August 2014 Available 18 July 2014 Accepted 26 May 2014 Submitted
Date of first compliant deposit:	29 December 2015
Volume:	Volume 136
Number:	Number 32
Number of Pages:	8
Page Range:	pp. 11444-11451
DOI:	10.1021/ja505266d
Status:	Peer Reviewed
Publication Status:	Published
Access rights to Published version:	Restricted or Subscription Access
Funder:	European Research Council (ERC), University of Warwick Vice Chancellor Scholarship, Lubrizol Ltd., Engineering and Physical Sciences Research Council (EPSRC), Birmingham Science City, Advantage West Midlands (AWM), European Regional Development Fund (ERDF)
Grant number:	ERC-2009-AdG 247143-QUANTIF (ERC), EP/F064861/1e (EPSRC)

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