Dual Band Electrodes in Generator-Collector Mode: Simultaneous Measurement of Two Species

TL;DR

This paper presents a computational method using dual band electrodes in generator-collector mode to simultaneously measure two electroactive species' concentrations by analyzing chronoamperometric data, leveraging differences in diffusion coefficients.

Contribution

It introduces a novel approach for simultaneous multi-species electrochemical measurement using a double band electrode and chronoamperometry, demonstrating its effectiveness through modeling and a practical example.

Findings

Measurement sensitivity is unaffected by electrode separation.

Wider electrode gaps increase the range of measurable collection times.

The method can detect small amounts of faster-diffusing species.

Abstract

A computational model for the simulation of a double band collector-generator experiment is applied to the situation where two electrochemical reactions occur concurrently. It is shown that chronoamperometric measurements can be used to take advantage of differences in diffusion coefficients to measure the concentrations of both electroactive species simultaneously, by measuring the time at which the collection efficiency reaches a specific value. The separation of the electrodes is shown to not affect the sensitivity of the method (in terms of percentage changes in the measured time to reach the specified collection efficiency), but wider gaps can provide a greater range of (larger) absolute values of this characteristic time. It is also shown that measuring the time taken to reach smaller collection efficiencies can allow for the detection of smaller amounts of whichever species diffuses faster. The case of a system containing both ascorbic acid and opamine in water is used to exemplify the method, and it is shown that mole fractions of ascorbic acid between 0.055 and 0.96 can, in principle, be accurately measured.