Coupling potentiostats & spectrometers for spectroelectrochemical measurements

Introduction

One of the possibilities of characterizing intermediate species created during a redox process is to couple a spectrometer with a potentiostat.

Different types of spectrometer can be used for this purpose, in accordance with the intrinsic properties of the intermediate species: UV-Vis, IR, Raman, fluorescence, NMR, EPR, XRD, etc. For example, the BioLogic Spectrometer system SEC2020 is a spectroelectrochemical kit made up of the spectrometer, the light source, and a cuvette holder. It is able to operate under transmittance, fluorescence, and irradiance modes.

However, to detect a species’ very short lifetime, the measurement has to be carried out in situ or in operando conditions.

What’s the difference between in situ and in operando characterisation?

In both cases, potentiostats (sometimes referred to as electrochemical workstations) are used to induce a change, and the spectrometer is used to characterize said change.

In operando measurement is less invasive than the in situ equivalent. For in operando measurements, the cell design has to be the same or very close to the cell design while it is running.

Let’s apply a zoological analogy: in situ characterizations concern the study of animals in a zoo, in operando characterizations concern the study of animals in their original (wild) environment.

Experimental challenges…

One of the most challenging aspects of spectroelectrochemical characterizations is the synchronization of the two separate instruments the potentiostat / galvanostat and the spectrometer. Most of the time, synchronization is managed by a trigger.

Another challenge is the customization of the cell in accordance with the necessary measurement. Most of the time, measurements are performed either in a bulk (Application Note #12) or onto thin film with a thin layer electrochemical cell (Application Note #52).