Characterization of a modular flow cell system for electrocatalytic experiments and comparison to a commercial RRDE system

TL;DR

This study introduces a modular flow cell system for electrocatalytic experiments, compares it to traditional RRDE systems, and demonstrates its flexibility and comparable collection efficiency through analytical, simulation, and experimental methods.

Contribution

We developed a flexible double electrode flow cell with exchangeable electrodes, providing an alternative to RRDEs with customizable geometry and materials for electrochemical analysis.

Findings

Collection efficiency close to 35.4% for all electrodes

Analytical solutions agree with measurements for certain electrode widths

Wider electrodes show unexpected dependence on width exponent

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.