Epinephrine electro-oxidation highlights fast electrochemistry at the graphite basal surface

Patel, Anisha N.; Tan, Sze‐yin; Unwin, Patrick R.

doi:10.1039/c3cc45022h

Cited by 31 publications

(68 citation statements)

References 21 publications

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“…Figure 3 shows characteristic CVs for repetitive cycling using three grades of HOPG: (a) AM, (b) ZYB and (c) SPI-3, and (d) pBDD. The behavior of the three different grades of HOPG is similar for the initial scan, even though the step edge densities vary by more than 2 orders of magnitude, 41 as shown in Figure 4. This strongly suggests that for graphite the electrochemical response is mainly determined by the basal surface, not the step edges.…”

Section: Repetitive Cyclic Voltammetric Responsementioning

confidence: 86%

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Electrochemical oxidation of dihydronicotinamide adenine dinucleotide (NADH): comparison of highly oriented pyrolytic graphite (HOPG) and polycrystalline boron-doped diamond (pBDD) electrodes

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Patel

et al. 2016

Phys. Chem. Chem. Phys.

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(2016) Electrochemical oxidation of dihydronicotinamide adenine dinucleotide (NADH) : Comparison of highly oriented pyrolytic graphite (HOPG) and polycrystalline boron-doped diamond (pBDD) electrodes. Physical Chemistry Chemical Physics. Permanent WRAP URL:http://wrap.warwick.ac.uk/81637 Copyright and reuse:The Warwick Research Archive Portal (WRAP) makes this work of researchers of the University of Warwick available open access under the following conditions. Copyright © and all moral rights to the version of the paper presented here belong to the individual author(s) and/or other copyright owners. To the extent reasonable and practicable the material made available in WRAP has been checked for eligibility before being made available.Copies of full items can be used for personal research or study, educational, or not-for-profit purposes without prior permission or charge. Provided that the authors, title and full bibliographic details are credited, a hyperlink and/or URL is given for the original metadata page and the content is not changed in any way. The electro-oxidation of nicotinamide adenine dinucleotide (NADH) is studied at bare surfaces of highly oriented pyrolytic graphite (HOPG) and semi-metallic polycrystalline boron-doped diamond (pBDD). A comparison of these two carbon electrode materials is interesting because they possess broadly similar densities of electronic states that are much lower than most metal electrodes, but graphite has carbon sp 2 -hybridization, while in diamond the carbon is sp 3 -hybridised, with resulting major differences in bulk structure and surface termination. Using cyclic voltammetry (CV), it is shown that NADH oxidation is facile at HOPG surfaces but the reaction products tend to strongly adsorb, which causes rapid deactivation of the electrode activity. This is an important factor that needs to be taken into account when assessing HOPG and its intrinsic activity. It is also shown that NADH itself adsorbs at HOPG, a fact that has not been recognized previously, but has implications for understanding the mechanism of the electro-oxidation process. Although pBDD was found to be less susceptible to surface fouling, pBDD is not immune to deterioration of the electrode response, and the reaction showed more sluggish kinetics on this electrode. Scanning electrochemical cell microscopy (SECCM) highlights a significant voltammetric variation in electroactivity between different crystal surface facets that are presented to solution with a pBDD electrode. The electroactivity of different grains correlates with the local dopant level, as visualized by field emission-scanning electron microscopy. SECCM measurements further prove that the basal plane of HOPG has high activity towards NADH electro-oxidation. These new insights on NADH voltammetry are useful for the design of optimal carbon-based electrodes for NADH electroanalysis.

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Section: Repetitive Cyclic Voltammetric Responsementioning

confidence: 86%

“…We make extensive use of macroscopic measurements at well-defined surfaces, for example, comparing the intrinsic activity of three different grades of HOPG that span step-edge density of more than 2 orders of magnitude. 29,41 Experimental section…”

Section: Introductionmentioning

confidence: 99%

Electrochemical oxidation of dihydronicotinamide adenine dinucleotide (NADH): comparison of highly oriented pyrolytic graphite (HOPG) and polycrystalline boron-doped diamond (pBDD) electrodes

Maddar

Lazenby

Patel

et al. 2016

Phys. Chem. Chem. Phys.

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“…Fresh HOPG basal surfaces were prepared by gently pressing down Scotch tape on to the sample and pullingoff the top layers, as reported extensively in the literature. 33,[60][61][62][63] Cyclic Voltammetry and SECM Instrumentation cm 2 ) with the counter and reference electrode placed into the droplet. 63 An advantage of this electrochemical cell is that it can be assembled and used within seconds of sample cleavage, 63 minimizing surface contamination.…”

Section: Electrode Materialsmentioning

confidence: 99%

Impact of Adsorption on Scanning Electrochemical Microscopy Voltammetry and Implications for Nanogap Measurements

et al. 2016

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“…AM, ZYA, SPI-1 and SPI-3 grade HOPG surfaces were freshly prepared for voltammetry measurements by peeling back the top layers of HOPG with Scotch tape, with the cleaving direction maintained to avoid deformation, until the tape was totally covered with HOPG, as routinely done in the literature. 27,37,40,41,49,50,57,[59][60][61] Fresh surfaces of AM HOPG were also revealed by mechanically cleaving with a clean razor blade, inserted perpendicular to the basal plane with a gentle rocking motion until a small piece delaminated spontaneously, as adopted elsewhere. 27,51,62 Both procedures were used for the macroscopic studies of AM grade HOPG, with samples respectively labelled as AM S and AM M .…”

Section: Materials and Reagentsmentioning

confidence: 99%

“…Thus, the electrochemistry of adsorbed AQDS at HOPG is analogous to that seen recently for other reactions: it is dominated by the basal surface. 37,40,41,[49][50][51][52][53][54][55] Time-resolved adsorption measurements: structure-activity analysis SECCM allows electrochemical measurements to be performed almost immediately after meniscus contact with the surface. 68 Coupled with the analysis of surface-bound redox species via FSCV, this allowed relatively fast adsorption to be followed in real-time.…”

Section: Impact Of Hopg Step Density On Adsorbed Electroactive Aqdsmentioning

confidence: 99%

Molecular Functionalization of Graphite Surfaces: Basal Plane versus Step Edge Electrochemical Activity

et al. 2014

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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 sp 2 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 (FSCV) protocol carried out with scanning electrochemical cell microscopy (SECCM) enables the evolution of AQDS adsorption to be followed locally on a rapid timescale. 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.3

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Epinephrine electro-oxidation highlights fast electrochemistry at the graphite basal surface

Cited by 31 publications

References 21 publications

Electrochemical oxidation of dihydronicotinamide adenine dinucleotide (NADH): comparison of highly oriented pyrolytic graphite (HOPG) and polycrystalline boron-doped diamond (pBDD) electrodes

Electrochemical oxidation of dihydronicotinamide adenine dinucleotide (NADH): comparison of highly oriented pyrolytic graphite (HOPG) and polycrystalline boron-doped diamond (pBDD) electrodes

Impact of Adsorption on Scanning Electrochemical Microscopy Voltammetry and Implications for Nanogap Measurements

Molecular Functionalization of Graphite Surfaces: Basal Plane versus Step Edge Electrochemical Activity

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