Microelectrodes voltammetry

Oldham K B 1991 Steady-state microelectrode voltammetry as a route to homogeneous kinetics J. Electroanal. Chem. 313 3... 

The main limitation to the use of microelectrode voltammetry is the need to measure small DC currents without noise interference. This usually requires that measurements be done in a Faraday cage (a shield against electronic noise). Recent reviews give good insight into the theory and application of microelec-trode voltammetry.48-51... 

The extent of distortion of the voltammogram from Eq. (36) can be measured and related to ko since the relationship between the two parameters has been determined by numerical solution of the mass-transport equation for microelectrode voltammetry under mixed kinetic-mass-transport control [105]. This approach has been used to determine ko values ( 1.0 cm s ) for the transfer of the laurate anion across the water-rc-octanol interface [106] and for the transfer of the tetramethylammonium ion ( 1.5 cm s ) across the water-DCE interface... 

Figure 16.21 Steady-state microelectrode voltammetry simulations for completely mono-disperse aUcylthiolate-protected d = 0.52 nm) gold nanoparticles with various core sizes (r) e = 3.0, T = 298 K, r values shown in nm. (Reproduced with permission from S. Chen et al., 1998. J. Phys. Chem. B 102 9898-9907. Copyright 1998 American Chemical Society.)...

Similar measurements using either walljet electrochemistry or steady-state microelectrode voltammetry have been reported for layer-by-layer assembled and interfadally polymerized materials, respectively [24,28]. Additional measmements were made spectrophotometrically with polymerized porphyrin squares by using a U-tube. Results summarized in Fig. 5 revealed the following (a) After normalizing for differences in film thickness, transport through polymeric membranes is two to three orders of magnitude faster... 

The diffusion studies described in the above sections pertain to water-continuous and bicontinuous microemulsions. Chen and Georges [34] were the first to study diffusion in oil-continuous microemulsions using steady-state microelectrode voltammetry. Ferrocene was used to probe diffusion in an SDS-dodecane-1-heptanol-water system. The diffusion coefficient of the hydrophobic probe indicated the microviscosity of the oil rather than the bulk viscosity of the microemulsion. Owlia et al. [36] reported diffusion coefficient measurements of water droplets in an Aerosol OT [AOT, bis(2-ethylhexyl)sulfosuccinate] microemulsion using a microelectrode. Water-soluble cobalt(II) corrin complex (vitamin Bi2r) was used in an oil-continuous microemulsion containing 0.2 M AOT, 4 M water buffered at pH 3, and isooctane. The apparent diffusion coefficient decreased with the probe concentration in accordance with Eq. (13) as shown in Fig. 6 [36]. The water droplet size was... 

Decreasing the size of the electrode so that the rate of radial diffusion of material to the electrode surface is enhanced. This is a key component in many important applications of microelectrode voltammetry. ... 

Oldham, K.B. (1988) Theory of microelectrode voltammetry with little electrolyte. Journal of Electroanalytical Chemistry, 250,1-21. 

Microelectrode voltammetry was used to study the mechanism of the catalysis by Co(II)(salen) of the reduction of butyl iodide, butyl bromide, and 1,2-dibromobutane in DMF and the influence of electrolytes on these reactions. The voltammetric characteristics can only be understood in terms of mechanisms that include additional steps to those proposed previously in the literature. ... 

In this chapter, the difhculties associated with applying conventional electroanalytical techniques, such as steady-state microelectrode voltammetry, RDE voltammetry, and dc cyclic voltanunetry with numerical simulation for the purpose of quantifying diffusivity in RTILs, are highlighted. In developing a strategy for overcoming these issues, we first outline the fundamentals of convolution voltammetry and then discuss a range of situations where electroanalytical applications of these techniques in RTILs have been employed successfully. 

Conventional Yoltammetric Techniques 5.2.1 Steady-State Microelectrode Voltammetry... 

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