R. Geoffrey Wellington

Voltammetry at C60-modified electrodes

Abstract The reduction of electrodes coated with C 60 -fullerene is examined in acetonitrile solution containing a wide variety of supporting electrolytes (MClO 4 ; M = Li, Na, Ba 0.5 , NR 4 ). Electrochemical intercalation is observed with the formation of fulleride salts. Intercalation is typically irreversible except for the case of R = n -butyl where stable coats of fullerides may be formed into which charge can be passed with near chemical reversibility. Electron-transfer reactions at electrodes modified with C 60 coatings were investigated for diverse substrates. With unreduced coats impeded diffusion to the metal surface was seen, whereas with films reduced in the presence of tetrabutylammonium perchlorate coat-mediated electron transfer to the substrate was possible.

Modelling electrode reactions using the strongly implicit procedure

Abstract The strongly implicit procedure is shown to be an easy-to-use stable, rapid and computationally efficient method of solving the coupled mass transport equations which describe complex electrode reactions involving diffusion, convection and homogeneous chemical steps. The method is illustrated with a diversity of problems pertaining to both microelectrodes and electrodes of conventional dimensions located in a rectangular channel through which electrolyte is pumped under laminar conditions. In all cases excellent agreement with experiment and/or existing analytical or numerical theory is noted.

Differential cyclic voltabsorptometry and chronoabsorptometry studies of ion transfer reactions at the water|1,2-dichloroethane interface

Abstract The combination of UV—visible absorption spectroscopy and conventional liquid|liquid electrochemistry is applied to study ion transfer at the liquid|liquid interface. Two separate examples of ion transfer are investigated. Results for Ru(bpy) 3 2+ and the dianionic form of Eosin B transfer from water to 1,2-dichloroethane, obtained using total internal reflection absorption spectroscopy, are presented. The techniques of differential cyclic voltabsorptometry and chronoabsorptometry are investigated and shown both to be specific to individual species and to produce responses analogous to conventional electrochemistry. A simple theory is presented and found to be an accurate description of the spectroscopic methodology.

TIME-RESOLVED LASER-INDUCED FLUORESCENCE STUDY OF PHOTOINDUCED ELECTRON TRANSFER AT THE WATER/1,2-DICHLOROETHANE INTERFACE

Reference LEPA-ARTICLE-1997-005View record in Web of Science Record created on 2005-11-07, modified on 2017-05-12

The photo-isomerisation of cis-azobenzene: A channel electrode study

The photo-isomerisation of cis-azobenzene by light of wavelength 432 nm has been investigated by channel electrode voltammetry. In a lithium ethoxide/ethanol medium cis-azobenzene was found to be reduced at a more positive potential (ca. 120 mV) than the trans isomer in the dark at a gold electrode. Quantitative waveshape measurements, with the electrode illuminated, of current-voltage curves for the reduction of the cis isomer as a function of the rate of mass transport, reveal the partial conversion of cis to trans and enable the quantum yield for the cis to trans isomerisation to be found as φ = 0.21.

Hydrodynamic voltammetry with channel microband electrodes : resolution of ECE and DISP1 processes

Abstract Gold microband channel electrodes (30 μ m in length) are used to study the reduction of ortho - bromonitrobenzene in dimethylformamide solution. An ECE mechanism is shown to operate and a rate constant of 250 s −1 for the chemical step is deduced. The ability to distinguish between ECE and DISP1 processes with the experimental protocol adopted is noted.

Iodide ion quenching of the photolysis of 1-iodoanthraquinone anion radical: evidence for an aryl radical–nucleophile reaction

The photolysis of 1-iodoanthraquinone anion radical in acetonitrile containing tetrabutylammonium iodide (TBA+I–) is unaffected by changes in [TBA+I–] up to 0.2 mol dm–3, confirming that the previously observed iodide ion quenching results from capture of photogenerated aryl radicals by the nucleophilic iodide, a process analogous to that in nucleophilic aromatic substitution by the SRN1 mechanism.