The relationship between the electrochemistry and the crystallography of microcrystals. The case of TCNQ (7,7,8,8-tetracyanoquinodimethane)†‡

Bond, Alan M.; Symons, Peter; Fletcher, Stephen

doi:10.1039/a805860a

Cited by 90 publications

(104 citation statements)

References 63 publications

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“…These values are in close agreement with those for the complex in 0.1 TBAP DMSO solution, in which the E 1/2 is +0.580V and ∆E p is 96mV. Also it is clear from the figure 5(a) that there is no significant change in either the peak currents or potentials or the presence of what is termed "inert zones" during the initial "breaking-in"process, as seen with other systems [63]. A scan rate study was performed on the microcrystals and it was found that the peak currents for both the oxidation and reduction processes were dependent upon the square root of the scan rate.…”

supporting

confidence: 78%

“…process, as seen with other systems [63]. A scan rate study was performed on the microcrystals and it was found that the peak currents for both the oxidation and reduction processes were dependent upon the square root of the scan rate.…”

Section: Solid State Electrochemistrymentioning

confidence: 99%

“…Scan rate studies were also performed at both pH 2.00 and 4.50, it was found that the peak potentials were independent of scan rate and that the peak currents of the associated redox processes were directly proportional to scan rates of up to 2Vs -1 at both pH values. process, as seen with other systems [63]. A scan rate study was performed on the microcrystals and it was found that the peak currents for both the oxidation and reduction processes were dependent upon the square root of the scan rate.…”

Section: Apparatus and Proceduresmentioning

confidence: 99%

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Solution and solid phase electrochemical behaviour of [Os(bpy)3]3[P2W18O62]

Fay¹,

Dempsey²,

McCormac³

2005

Electrochimica Acta

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Abstract[Os (bpy) indicating surface based processes were present. Electroactive films of the complex were formed on carbon macroelectrodes by the redox switching of the transition metal within the complex. Voltammetric investigations into the film's behaviour in a range of buffer solutions (pH 2.0, 4.5 and 7.0) were performed. The films were found to possess better stability in acidic pH and the same pH dependence for the tungsten-oxo framework of the heteropolyanions as in solution. Solid state electrochemical measurements on mechanically attached microparticles of the complex were performed, with the effect of both the nature and concentration of the aqueous electrolyte on this behaviour being investigated. Upon redox switching between the Os 2+/3+ redox states there is an associated insertion/expulsion of anions from/to the solution phase. Scanning electron micrographs of these solid state films were attained before and after redox cycling. Apparatus and ProceduresThe reference electrode that was employed in organic solvents was a silver wire in contact IR SpectroscopyThe Differential pulse anodic stripping voltammetric (DPASV) experiments were performed so as to confirm the adsorption phenomenon observed in 0.01M electrolyte concentration. Figure 3 illustrates the DPASV of a modified carbon electrode in 0.1M Et 4 NPF 6 after an accumulation step at - As discussed in the previous section the oxidative processes of the Os 2+ centre exhibits characteristics pointing to an interaction between the complex and the electrode surface. As a result a film of the complex could be deposited onto the electrode surface by continuous redox switching through the osmium metal redox couple. Films were formed by cycling the potential of the glassy carbon electrode through the Os 3+/2+ redox process for 250 cycles from 9 a 0.1M TBAPF 6 DMSO solution of the starting complex. Figure 4 [79,80]. Despite the FWHM pointing to the first redox process being monoelectronic we believe it is bielectronic for two reasons. At slower scan rates a slight shoulder has been observed on the first redox process and it is well known that the first two monoelectronic processes are very close in potential. Secondly it is well know that the parent HPA can accept 6 electrons reversibly.The P 2 W 18 O 62 6-Dawson species is stable in pH's from 2.00 to 8.00 and its electrochemical behaviour depends upon the pH of the contacting electrolyte with some of the tungsten-oxo based redox processes involving protonation [75]. As a result we were interested in investigating the effect of solution pH on the redox activity of the film. With increasing pH, the losses. The lower stability of the film towards redox cycling in pH 4.50 is linked to the pH dependent nature of the tungsten-oxo reductions, when at more alkaline pH's the availability of protons which accompany the reductions is less, relative to that in pH 2.00. Scan rate studies were also performed at both pH 2.00 and 4.50, it was found that the peak potentials were independent of scan rate and th...

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supporting

confidence: 78%

Section: Solid State Electrochemistrymentioning

confidence: 99%

Section: Apparatus and Proceduresmentioning

confidence: 99%

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Solution and solid phase electrochemical behaviour of [Os(bpy)3]3[P2W18O62]

Fay¹,

Dempsey²,

McCormac³

2005

Electrochimica Acta

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“…[10][11][12][13] TCNQ (TTF) is reduced (oxidised) to TCNQ À (TTF + ) under conditions of cyclic voltammetry to form the monovalent species. In order to maintain charge neutrality, simultaneously with reduction (oxidation) involving transfer of electrons from (to) the electrode, counter ions in the solution must ingress into the microcrystals.…”

Section: Introductionmentioning

confidence: 99%

Applications of voltammetric ion selective electrodes to complex matrices

2013

Self Cite

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The practical application of two different voltammetric ion selective electrodes (VISE) to measure ion activity in complex solutions has been explored. 7,7,8, and tetrathiafulvalene (TTF) microcrystals adhered to an electrode surface act as a low selectivity voltammetric ion sensor. Resistance drop effects and pH artifacts were minimised by the addition of an "innocent" supporting electrolyte (buffer) to the analyte solution. In this format, addition of an ionophore to improve selectivity resulted in a reduction in current magnitude, due to competition for the ion. In contrast, voltammetry of a thin film containing a redox active species, electrolyte, ionophore and membrane solvent provides a highly selective ion sensor. Choice of ionophore was shown to affect the upper concentration detection limit. Use of ionic liquids as a combined membrane solvent and electrolyte was demonstrated. Methods to attach both VISE types to low-cost screen-printed electrodes have been explored. Various potential referencing techniques were also investigated. Both the microcrystal and thin film VISEs could be used to determine ion activity in complex solutions, as demonstrated in seawater, beverages, plasma and whole blood. Dissolved oxygen does not need to be removed, as it does not affect the response. However calibration methods are important for sensor accuracy and issues relating to electrode fouling must be addressed. The practical application of two different voltammetric ion selective electrodes (VISE) to measure ion activity in complex solutions has been explored. 7,7,8, and tetrathiafulvalene (TTF) microcrystals adhered to an electrode surface act as a low selectivity voltammetric ion sensor. Resistance drop effects and pH artifacts were minimised by the addition of an "innocent" supporting electrolyte (buffer) to the analyte solution. In this format, addition of an ionophore to improve selectivity resulted in a reduction in current magnitude, due to competition for the ion. In contrast, voltammetry of a thin film containing a redox active species, electrolyte, ionophoreand membrane solvent provides a highly selective ion sensor. Choice of ionophore was shown to affect the upper concentration detection limit. Use of ionic liquids as a combined membrane solvent and electrolyte was demonstrated. Methods to attach both VISE types to low-cost screen-printed electrodes have been explored. Various potential referencing techniques were also investigated. Both the microcrystal and thin film VISEs could be used to determine ion activity in complex solutions, as demonstrated in seawater, beverages, plasma and whole blood. Dissolved oxygen does not need to be removed, as it does not affect the response. However calibration methods are important for sensor accuracy and issues relating to electrode fouling must be addressed.

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“…Another hypothesis is that the current scan rate of 1 mV s -1 could be too fast to detect the electrochemical response. It is well-known that the separation between redox peaks, ΔEa,c is the combination of two main factors such as the ohmic drop and the energetics of the ion insertion-expulsion reaction, 20),21) the latter factor includes many parameters such as proton concentration, the electrolytic concentration and so on. On the other hand, the electrode can only intercalate or deintercalate the number of proton commensurate with the volume of the active material available.…”

Section: Methodsmentioning

confidence: 99%

Preparation of .ALPHA.-nickel hydroxide/carbon composite by the liquid phase deposition method

Béléké

Hosokawa

Mizuhata

et al. 2009

J. Ceram. Soc. Japan

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High purity α-nickel hydroxide/carbon composite has been synthesized by the liquid phase deposition (LPD) method. The purity of the as-prepared samples was confirmed by X-ray photon electron (XPS) survey spectra, which showed no other peak than that of the core levels Ni 2p, O 1s, C1s, Ni 3s and Ni 3p involved in the process. Scanning electron microscope (SEM) images showed carbon particles randomly embedded within the Ni(OH)2 network. The amount of deposited nickel hydroxide can be controlled by the ratio between carbon and the quantity of the treatment solution, and the reaction time.

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The relationship between the electrochemistry and the crystallography of microcrystals. The case of TCNQ (7,7,8,8-tetracyanoquinodimethane)†‡

Cited by 90 publications

References 63 publications

Solution and solid phase electrochemical behaviour of [Os(bpy)3]3[P2W18O62]

Solution and solid phase electrochemical behaviour of [Os(bpy)3]3[P2W18O62]

Applications of voltammetric ion selective electrodes to complex matrices

Preparation of .ALPHA.-nickel hydroxide/carbon composite by the liquid phase deposition method

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