Convective mass transfer to partially recessed and porous electrodes

Electrochemical properties of aryl-modified gold electrodes

“…It should be noted that, as discussed in Ref. [66], for a recessed and partially blocked electrode, there is a range of pore sizes and thickness of the porous film covering the electrode surface for which the value of n calculated from the Koutecky-Levich equation is independent of the surface available for reaction since changes in the current with rotation rate are determined only by the changes of the thickness of the diffusion layer [66]. It was argued in this work that when a fullerene film covers the electrode surface, oxygen reduction changed from a 4e À to a 2e À mechanism due to the suppression of the bridge adsorption of oxygen on Au.…”

“…The response of the PhBr filmed electrode is very different and is characteristic of a microelectrode array or that of a partially recessed and blocked electrode [66]. Since the film thickness is approximately 30-50 nm (data from AFM images), the diffusional contribution across the film will be negligible [66] and therefore, the behaviour can be modelled as that of a microelectrode array.…”

“…Since the film thickness is approximately 30-50 nm (data from AFM images), the diffusional contribution across the film will be negligible [66] and therefore, the behaviour can be modelled as that of a microelectrode array. Thus, due to its open structure, the film partially blocks the transport of the dopamine molecules to the gold surface.…”

Investigation of Oxygen Reduction Reaction Kinetics at (111)−(100) Nanofaceted Platinum Surfaces in Acidic Media

“…The validity of the Levich equation for the case of a disk with partially active surface areas has been tested in simple geometries, such as circular active sites distributed on an inactive RDE by Landsberg and Thiele 18 and, more recently, an inactive film with circular pores covering an active RDE by Ahlberg et al 19 According to their results, if the thickness of the diffusion layer δ d is much larger than the length scales of electrode inhomogeneities, like in our case, reaction rates can simply be replaced by effective rates and currents still follow Koutecký-Levich type behavior, albeit one exception of the nonzero intercept even in the diffusion controlled potential region. However, our data shown in the insets of Figure 6 and Figure 7 exhibit significant deviations from the expected linear behavior.…”

Biosorption of hexacyanoferrate(III) complex anion to dead biomass of the basidiomycete Pleurotus mutilus: Biosorbent characterization and batch experiments

“…14). The D i values were significantly higher for large biomass particles than for thinner ones, but remained very low compared to the diffusion coefficient of hexacyanoferrate ions in water, i.e., around 7 × 10 −10 m 2 s −1 [59,60]. They were in the range of literature data [49,54,56], however.…”