Electron hopping rate measurements in ITO junctions: Charge diffusion in a layer-by-layer deposited ruthenium(II)-bis(benzimidazolyl)pyridine-phosphonate–TiO2 film

Cummings, Charles Y.; Wadhawan, Jay D.; Nakabayashi, Takakazu; Haga, Masa‐aki; Rassaei, Liza; Dale, Sara E. C.; Bending, S. J.; Pumera, Martin; Parker, Stephen C.; Marken, Frank

doi:10.1016/j.jelechem.2011.04.010

Cited by 14 publications

(11 citation statements)

References 24 publications

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“…Assuming a diffusion-dominated charge propagation mechanism, it is possible to estimate the apparent diffusion coefficient from τ ¼ δ 2 πD as D≈10 −15 m 2 s −1 (based on δ≈50 nm, see Fig. 2), which is consistent with typical charge hopping processes [36]. This rate of charge hopping is considerably slower when compared to substrate diffusion in the film and therefore one of the ratelimiting factors in the catalytic reaction (vide infra).…”

Section: Resultssupporting

confidence: 58%

Polymer of Intrinsic Microporosity Induces Host-Guest Substrate Selectivity in Heterogeneous 4-Benzoyloxy-TEMPO-Catalysed Alcohol Oxidations

et al. 2015

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The free radical 4-benzoyloxy-2,2,6,6-tetramethylpiperidine-1-oxyl (4B-TEMPO) is active as an electrocatalyst for primary alcohol oxidations when immobilised at an electrode surface and immersed into an aqueous carbonate buffer solution. In order to improve the catalytic process, a composite film electrode is developed based on (i) carbon microparticles of 2-12 μm diameter to enhance charge transport and (ii) a polymer of intrinsic microporosity (here PIM-EA-TB with a BET surface area of 1027 m 2 g −1 ). The latter acts as a highly rigid molecular framework for the embedded free radical catalyst with simultaneous access to aqueous phase and substrate. The resulting mechanism for the oxidation of primary alcohols is shown to switch in reaction order from first to zeroth with increasing substrate concentration consistent with a kinetically limited process with competing diffusion of charge at the polymer layer-electrode interface (here the BLEk^case in Albery-Hillman notation). Reactivity optimisation and screening for a wider range of primary alcohols in conjunction with DFT-based relative reactivity correlation reveals substrate hydrophobicity as an important factor for enhancing catalytic currents. The PIM-EA-TB host matrix is proposed to control substrate partitioning and thereby catalyst reactivity and selectivity.

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Section: Resultssupporting

confidence: 58%

Polymer of Intrinsic Microporosity Induces Host-Guest Substrate Selectivity in Heterogeneous 4-Benzoyloxy-TEMPO-Catalysed Alcohol Oxidations

et al. 2015

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“…This situation is similar to that observed for example in films containing molecular redox systems, which have been extensively studied for example on inter-digitated band electrodes [42]. With this assumption, it is possible to formally apply the Dahms-Ruff model [43][44][45] for the evaluation of the self-exchange rate constant k SE (see Eq. (7)).…”

Section: Chronoamperometry At Gold-gold Generator-collector Electrodesupporting

confidence: 67%

Inter-particle charge transfer in TiO2-phytate films: Generator–collector gold–gold junction transients

Rassaei

Herrmann

Gordeev

et al. 2012

Journal of Electroanalytical Chemistry

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“…The main assumption to explain this behaviour is to consider the coexistence of various physical and/or chemical environments for the TEMPO units which play an important role in their electroactivity. As already observed for thick layers, at high scan rate, it is quite possible that the diffusion of the electrolyte solution to the less accessible redox centers becomes the limiting step of the redox process, leading to the partial electrochemical response of the film.…”

Section: Figurementioning

confidence: 67%

Impact of the Diazonium Grafting Control on the Interfacial Reactivity: Monolayer versus Multilayer

et al. 2016

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A very simple strategy to prepare, in two steps, a versatile and sustainable monolayer platform for on‐surface chemistry is presented. The first step consists of the electroreduction of well‐known 4‐nitrobenzenediazonium in the presence of a radical scavenger, leading to a covalent monolayer surface modification. Then, a dense reactive phenylamine monolayer is obtained through the full electroreduction of the nitrophenyl moieties. The platform thus obtained is available for post‐functionalization with carboxyl derivatives through a usual peptide coupling. Attachment of a TEMPO unit, offering both redox and electrocatalytic properties, validates this approach and leads to high surface coverage and fast electron transfer. A comparison of the electrochemical properties of the modified surface with a classical multilayered post‐functionalized one highlights important differences in terms of interfacial reactivity. The results presented here justify the interest in preparing a reactive monolayer platform for molecule grafting and paves the way for simple and controlled surface chemistry without the need of synthesis.

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Electron hopping rate measurements in ITO junctions: Charge diffusion in a layer-by-layer deposited ruthenium(II)-bis(benzimidazolyl)pyridine-phosphonate–TiO2 film

Cited by 14 publications

References 24 publications

Polymer of Intrinsic Microporosity Induces Host-Guest Substrate Selectivity in Heterogeneous 4-Benzoyloxy-TEMPO-Catalysed Alcohol Oxidations

Polymer of Intrinsic Microporosity Induces Host-Guest Substrate Selectivity in Heterogeneous 4-Benzoyloxy-TEMPO-Catalysed Alcohol Oxidations

Inter-particle charge transfer in TiO2-phytate films: Generator–collector gold–gold junction transients

Impact of the Diazonium Grafting Control on the Interfacial Reactivity: Monolayer versus Multilayer

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