Measurement of entropy change of a half-cell electrochemical reaction using Multi-harmonic ElectroThermal Spectroscopy (METS)

In this work, we describe our newly established electrochemical method: Muti-harmonic Electrothermal Spectroscopy (METS) and explain how it can be used to resolve the entropy change at individual electrochemical electrodes. The entropy change of an electrochemical reaction can be related to the entropic coefficient, which is the temperature coefficient of the cell potential. Traditionally, this entropic coefficient is measured either through calorimetry or by measuring the cell potential as a function of temperature. However, these methods are limited to measuring the overall entropy change at both electrodes and cannot resolve the entropy change due to individual half-cell reactions at each electrode. With METS however, we are able to resolve the heat generation due to entropy change with a spatial resolution of a few microns, which allows attributing the change in entropy for half-cell reactions at individual electrodes, which are separated with each other by 10s of microns.