Adsorption coupled electrode kinetics of bipyridylium-based herbicides

Pospı́šil, Lubomı́r; Kůta, J.; Volke, J.

doi:10.1016/s0022-0728(75)80354-8

Cited by 43 publications

(13 citation statements)

References 11 publications

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“…Previous studies in aqueous solution have found evidence that methyl viologen adsorbs on the surface of the working electrode, complicating the analysis of kinetic data . However, in MeCN we find that the peak currents for both the forward (cathodic) and reverse (anodic) processes were directly proportional to the square root of the scan rate over the range 0.1 to 100 V s −1 , which indicates that adsorption of neither the dication nor the radical cation occurred to any significant extent in MeCN .…”

Section: Resultscontrasting

confidence: 60%

“…To our knowledge, the standard electron‐transfer rate constant for the one‐electron reduction of methyl viologen in acetonitrile has never been reported. Attempts to study the rate in aqueous solvents have been made but they are complicated by adsorption phenomena and dimerisation of the reaction products . Electrode fouling due to electrodeposition of the neutral form of the molecule has also been observed in aqueous solvents .…”

Section: Introductionmentioning

confidence: 99%

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Heterogeneous Electron‐Transfer Rates for the Reduction of Viologen Derivatives at Platinum and Bismuth Electrodes in Acetonitrile

Cook

Horrocks

2016

ChemElectroChem

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The standard heterogeneous rate constants for the reduction of a series of viologen derivatives with a range of inter‐ring torsion angles were measured at Bi and Pt electrodes. The electrode potentials for the first one‐electron reduction of the viologens vary from −684 mV to −1070 mV vs. Ag/0.01 m Ag+; this enabled a comparison of the behaviour of metallic (Pt) and semi‐metallic (Bi) electrodes over a wide range of applied potentials. The differential capacitance (6.5 μF cm−2) of Bi/MeCN,TBAPF6 interfaces at the potential of zero charge (pzc=−0.60 V) is at least an order of magnitude greater than that calculated on the basis of the bulk Bi carrier density (3×1017 cm−3) and the differential capacitance (9.5 μF cm−2) of Pt/MeCN interfaces at their pzc (−0.43 V) is of the same order. The series of viologen derivatives exhibited simple one‐electron redox behaviour and showed similar rate constants at Pt (1.8×10−4–1.6×10−3 cm s−1) and Bi electrodes (1.1×10−4–1.9×10−3 cm s−1) after application of the Frumkin correction. These results demonstrate that the density of states at the Bi surface is much higher than in bulk. Finally, the Frumkin‐corrected standard rate constants were observed to be inversely correlated with the inter‐ring torsion angle of the viologens.

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Section: Resultscontrasting

confidence: 60%

Section: Introductionmentioning

confidence: 99%

Heterogeneous Electron‐Transfer Rates for the Reduction of Viologen Derivatives at Platinum and Bismuth Electrodes in Acetonitrile

Cook

Horrocks

2016

ChemElectroChem

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“…[32] Paraquat and diquat are the selective contact herbicides most frequently used of this family. The two compounds are usually called "methylviologen" because, on reduction, they give rise to stable, blue or violet radicals.…”

Section: Bipyridinium Pesticidesmentioning

confidence: 99%

Electrochemical Methods in Pesticides Control

et al. 2004

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The state of the art of voltammetric and amperometric methods used in the study and determination of pesticides in crops, food, phytopharmaceutical products, and environmental samples is reviewed. The main structural groups of pesticides, i.e., triazines, organophosphates, organochlorides, nitrocompounds, carbamates, thiocarbamates, sulfonylureas, and bipyridinium compounds are considered with some degradation products. The advantages, drawbacks, and trends in the development of voltammetric and amperometric methods for study and determination of pesticides in these samples are discussed.

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“…1,1 0 -Dimethyl-4,4 0 -bipyridinium dichloride (also known as methylviologen or paraquat) is commonly used as a nonselective contact herbicide due to its extreme toxicity linked to its redox potential. 1,2 The compound has attracted considerable attention from electrochemists over the past years due to its favourable redox properties resulting in many possible electrochemical applications. 3 The electrochemical kinetics of methylviologen in aqueous solution have been extensively studied in the past, and several different mechanisms have been proposed to explain the observed voltammetry on numerous electrode materials.…”

Section: Introductionmentioning

confidence: 99%

“…respectively. [1][2][3][4][5][6][8][9][10][11][12][13][14] In the anodic process, a ''poorly defined'' peak may be observed at ca. À0.9 V and has been suggested to arise from the electrode reaction:…”

Section: Introductionmentioning

confidence: 99%

Investigating the voltammetric reduction of methylviologen at gold and carbon based electrode materials. Evidence for a surface bound adsorption mechanism leading to electrode ‘protection’ using multi-walled carbon nanotubes

2008

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Cyclic voltammetry was recorded in an aqueous solution of 1,1'-dimethyl-4,4' bipyridinium dichloride (“methylviologen” or “paraquat”) at a variety of electrode materials namely gold, boron doped diamond (BDD), edge (eppg) and basal plane (bppg) pyrolytic graphite electrode. Previous mechanisms reported in the literature to describe the observed voltammetry are critically assessed and an alternative mechanistic interpretation is presented involving evidence for surface adsorption of intermediate species in the redox behaviour of methylviologen (MV) rather than any disproportionation or comproportionation as was previously claimed for the specific case of gold electrodes. Various electrodes were then modified with multi-walled carbon nanotubes (MWCNTs) where the formation of solid MV0 on the electrode surface was prevented due to preferential adsorption of MV0 on the MWCNTs. Thus coating an electrode with MWCNTs can protect the electrode surface from “fouling”, providing scope for diffusion dominated voltammetry at electrodes where surface inhibition has hitherto dominated

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Adsorption coupled electrode kinetics of bipyridylium-based herbicides

Cited by 43 publications

References 11 publications

Heterogeneous Electron‐Transfer Rates for the Reduction of Viologen Derivatives at Platinum and Bismuth Electrodes in Acetonitrile

Heterogeneous Electron‐Transfer Rates for the Reduction of Viologen Derivatives at Platinum and Bismuth Electrodes in Acetonitrile

Electrochemical Methods in Pesticides Control

Investigating the voltammetric reduction of methylviologen at gold and carbon based electrode materials. Evidence for a surface bound adsorption mechanism leading to electrode ‘protection’ using multi-walled carbon nanotubes

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