A UV-visible rapid scan spectrophotometer (RSS) was coupled to a Au rotating disk electrode (RDE) for monitoring at near-normal incidence the reflection-absorption spectrum of the diffusion boundary layer in [Fe(CN) 6]4- aqueous solutions over a potential region in which [Fe(CN)6]4- oxidizes, generating highly absorbing [Fe-(CN)6]3- (λmax = 420 nm). Measurements were performed under steady-state conditions at rotation rates, ω, in the range 300 ≤ ω ≤ 2500 rpm, yielding well-defined spectra displaying characteristic features of [Fe(CN)6] 3-. In agreement with theoretical predictions, the absorbance A at λmax, using as a reference A(λmax) for the spectrum recorded at a potential negative to the onset of [Fe(CN) 6]4- oxidation, was found to be proportional both to the current and also to ω1/2 under conditions in which E was positive enough for the reaction to proceed under diffusion-limited control.
ASJC Scopus subject areas
- Analytical Chemistry