Abstract
Generator-collector
experiments offer insights into the mechanisms of electrochemical reactions by
correlating the product and generator currents. Most commonly, these
experiments are performed using a rotating ring-disk electrode (RRDE). We
developed a double electrode flow cell (DEFC) with exchangeable generator and
detector electrodes where the electrode width equals the channel width.
Commonalities and differences between the RRDE and DEFC are discussed based on
analytical solutions, numerical simulations and measurements of the
ferri-/ferrocyanide redox couple on Pt electrodes in a potassium chloride
electrolyte. The analytical solutions agree with the measurements using
electrode widths of 5 and 2 mm. Yet, we find an unexpected dependence on the
exponent of the width so that wider electrodes cannot be analysed using the
conventional analytical solution. In contrast, all the investigated electrodes
show a collection efficiency of close to 35.4% above a minimum rotation speed
or flow rate, where the narrowest electrode is most accurate at the cost of
precision and the widest electrode the least accurate but most precise. Our
DEFC with exchangeable electrodes is an attractive alternative to commercial RRDEs
due to the flexibility to optimize the electrode materials and geometry for the
desired reaction.