Electrochemical Mapping Reveals Direct Correlation between Heterogeneous Electron‐Transfer Kinetics and Local Density of States in Diamond Electrodes

Patten, Hollie V.; Meadows, Katherine E.; Hutton, Laura A.; Iacobini, James G.; Battistel, Dario; McKelvey, Kim; Colburn, Alexander W.; Newton, Mark E.; Macpherson, Julie V.; Unwin, Patrick R.

doi:10.1002/anie.201203057

Cited by 110 publications

(101 citation statements)

References 64 publications

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“…57 As seen in Figure 4b, increasing the defect density can lead to a higher DOS (from solid to dashed green line) that will lead to a faster kinetics. In this moderate defect density range, single layer graphene becomes much more activated and leads to higher k 0 as observed.…”

Section: Resultsmentioning

confidence: 91%

Quantitative Correlation between Defect Density and Heterogeneous Electron Transfer Rate of Single Layer Graphene

et al. 2014

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Improving electrochemical activity of graphene is crucial for its various applications, which requires delicate control over its geometric and electronic structures. We demonstrate that precise control of the density of vacancy defects, introduced by Ar(+) irradiation, can improve and finely tune the heterogeneous electron transfer (HET) rate of graphene. For reliable comparisons, we made patterns with different defect densities on a same single layer graphene sheet, which allows us to correlate defect density (via Raman spectroscopy) with HET rate (via scanning electrochemical microscopy) of graphene quantitatively, under exactly the same experimental conditions. By balancing the defect induced increase of density of states (DOS) and decrease of conductivity, the optimal HET rate is attained at a moderate defect density, which is in a critical state; that is, the whole graphene sheet becomes electronically activated and, meanwhile, maintains structural integrity. The improved electrochemical activity can be understood by a high DOS near the Fermi level of defective graphene, as revealed by ab initio simulation, which enlarges the overlap between the electronic states of graphene and the redox couple. The results are valuable to promote the performance of graphene-based electrochemical devices. Furthermore, our findings may serve as a guide to tailor the structure and properties of graphene and other ultrathin two-dimensional materials through defect density engineering.

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Section: Resultsmentioning

confidence: 91%

Quantitative Correlation between Defect Density and Heterogeneous Electron Transfer Rate of Single Layer Graphene

et al. 2014

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“…21,[24][25][26][27][28][29][30] An attractive feature of SECCM is that each location on the electrode is only exposed to the electrolyte solution briefly, minimizing electrode fouling 21 and other undesired processes. In contrast to scanning electrochemical microscopy (SECM), 31,32 which is also powerful for visualizing heterogeneous electrode substrates, [33][34][35][36] SECCM measures the electrochemical processes of interest directly, in a manner that is similar to conventional dynamic electrochemistry, and readily achieves higher spatial resolution.…”

Section: Introductionmentioning

confidence: 99%

“…This is particularly true for the Fe 2+/3+ redox process. 47,50 Based on our recent work, 21,[24][25][26][27][28][29]33,51 SECCM provides a powerful method to investigate whether structural effects hold for the oxidation of Fe 2+ on polycrystalline platinum.…”

Section: Introductionmentioning

confidence: 99%

Pseudo-Single-Crystal Electrochemistry on Polycrystalline Electrodes: Visualizing Activity at Grains and Grain Boundaries on Platinum for the Fe²⁺/Fe³⁺ Redox Reaction

et al. 2013

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The influence of electrode surface structure on electrochemical reaction rates and mechanisms is a major theme in electrochemical research, especially as electrodes with inherent structural heterogeneities are used ubiquitously. Yet, probing local electrochemistry and surface structure at complex surfaces is challenging. In this paper, high spatial resolution scanning electrochemical cell microscopy (SECCM) complemented with electron backscatter diffraction (EBSD) is demonstrated as a means of performing ‘pseudo-single-crystal’ electrochemical measurements at individual grains of a polycrystalline platinum electrode, while also allowing grain boundaries to be probed. Using the Fe2+/3+ couple as an illustrative case, a strong correlation is found between local surface structure and electrochemical activity. Variations in electrochemical activity for individual high index grains, visualized in a weakly adsorbing perchlorate medium, show that there is higher activity on grains with a significant (101) orientation contribution, compared to those with (001) and (111) contribution, consistent with findings on single-crystal electrodes. Interestingly, for Fe2+ oxidation in a sulfate medium a different pattern of activity emerges. Here, SECCM reveals only minor variations in activity between individual grains, again consistent with single-crystal studies, with a greatly enhanced activity at grain boundaries. This suggests that these sites may contribute significantly to the overall electrochemical behavior measured on the macroscale.

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“…31 Indeed we have recently built an ultra-sensitive flow-cell for dopamine detection based on metallic single-walled carbon nanotubes. 32 Our choice of a MWCNT-epoxy composite electrode was a compromise between excellent electrochemical performance and ease of fabrication into an electrode small enough to be incorporated into a robust microfluidic cell.…”

Section: Resultsmentioning

confidence: 99%

Real-time detection of carboplatin using a microfluidic system

Phairatana

Leong

Gowers

et al. 2016

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Electrochemical Mapping Reveals Direct Correlation between Heterogeneous Electron‐Transfer Kinetics and Local Density of States in Diamond Electrodes

Cited by 110 publications

References 64 publications

Quantitative Correlation between Defect Density and Heterogeneous Electron Transfer Rate of Single Layer Graphene

Quantitative Correlation between Defect Density and Heterogeneous Electron Transfer Rate of Single Layer Graphene

Pseudo-Single-Crystal Electrochemistry on Polycrystalline Electrodes: Visualizing Activity at Grains and Grain Boundaries on Platinum for the Fe²⁺/Fe³⁺ Redox Reaction

Real-time detection of carboplatin using a microfluidic system

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Electrochemical Mapping Reveals Direct Correlation between Heterogeneous Electron‐Transfer Kinetics and Local Density of States in Diamond Electrodes

Cited by 110 publications

References 64 publications

Quantitative Correlation between Defect Density and Heterogeneous Electron Transfer Rate of Single Layer Graphene

Quantitative Correlation between Defect Density and Heterogeneous Electron Transfer Rate of Single Layer Graphene

Pseudo-Single-Crystal Electrochemistry on Polycrystalline Electrodes: Visualizing Activity at Grains and Grain Boundaries on Platinum for the Fe2+/Fe3+ Redox Reaction

Real-time detection of carboplatin using a microfluidic system

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Pseudo-Single-Crystal Electrochemistry on Polycrystalline Electrodes: Visualizing Activity at Grains and Grain Boundaries on Platinum for the Fe²⁺/Fe³⁺ Redox Reaction