CHANNEL FLOW CELL FOR ATTENUATED TOTAL-REFLECTION FOURIER-TRANSFORM INFRARED SPECTROELECTROCHEMISTRY

A channel-type spectroelectrochemical cell is described for the acquisition of potential difference (PD) attenuated total reflection Fourier transform infrared (ATR-FT-IR) spectroscopy of solution phase species generated at an electrode surface under conditions of well-defined laminar now, The capabilities of the cell have been assessed using the reduction of bisulfite (2 M) in a weakly acidic (pH = 5.25), unbuffered, aqueous electrolyte as a model system, The PD ATR-FT-IR spectrum obtained at -0.85 V vs SCE, a potential negative enough for the reduction of HSO3- to proceed, compared to the spectrum recorded at a potential at which no reaction occurs (0.0 V vs SCE) as a reference, was dominated by negative- and positive-pointing contributions due to the reactant, bisulfite, and the predominant product, dithionite, respectively, Also identified in the spectrum was sulfite, which is produced by the dissociation of bisulfite induced by the increase in the pH of the medium during the reduction reaction, Theoretical aspects regarding the quantitative analysis of these data are briefly discussed.