Observation of Kinetic Isotope Effect in Electrocatalysis with Fully Deuterated Ultrapure Electrolytes

TL;DR

This study demonstrates that observing kinetic isotope effects in electrocatalysis requires ultrapure deuterated electrolytes, revealing the importance of electrolyte purity in understanding microscopic reaction mechanisms.

Contribution

The paper introduces a reliable method using fully deuterated ultrapure electrolytes to observe KIE in electrocatalysis, addressing impurity sensitivity issues.

Findings

Electrolyte purity critically affects KIE measurements.

Highly pure deuterated electrolytes are essential for accurate electrocatalytic studies.

The approach enables investigation of complex proton transfer reactions.

Abstract

Kinetic isotope effect (KIE) is a common physicochemical effect to elucidate complicated microscopic reaction mechanism in biological, chemical and physical systems. Especially, the exchange of hydrogen to deuterium is a standard approach to investigate kinetics and pathways of a wide spectrum of key reactions involving proton transfer. However, KIE in electrocatalysis is still challenge. One main reason is owing to the high sensitivity to impurities in electrochemical systems. Aiming to establish an appropriate approach to observe KIE in electrocatalysis, we investigated KIE in electrocatalysis by using fully deuterated ultrapure electrolytes. With these electrolytes, we studied oxygen reduction reaction with platinum catalyst, which is well-known to be sensitive to impurity, as the model systems. In conclusion, the electrode processes in these systems can be strongly influenced by a purity of a selected deuterated electrolyte, especially in case of alkaline conditions. Therefore a highly pure deuterated electrolyte is indispensable to study microscopic electrode processes of electrocatalysis by analyzing KIE. This work shows a key criterion and methods to observe a reliable KIE in electrocatalytic systems, and therefore, provides a general approach to investigate complicated multielectron- and multiproton-transfer processes using not only standard electrochemical technique but also surface sensitive spectrometry.