The Adequate Amount of Acid‐Base Buffer for Electrochemical Investigation of Proton‐Coupled Electron Transfer Reactions

Abstract

The effective pH occurs near the electrode surface in dilute solutions as protons are released or absorbed during proton‐coupled electron transfer (PCET) reactions. We utilize cyclic voltammetry to study the electrochemical behavior of hydroquinone, p‐benzoquinone, ascorbic acid, and dopamine in phosphate buffer. The effective pH causes peak potential changes and new peak formation. However, the electrochemical behavior of hydroquinone is independent of the buffer when the HPO42−(proton acceptor) concentration is 4.05–6 times greater than that of hydroquinone. Similar results are obtained for quinone in phosphate buffer solution. Dopamine undergoes cyclization during electrochemical oxidation, which also releases protons. Therefore, a high amount of buffer is required. Moreover, the amount of acid‐base buffer strongly affects the electrochemical behaviors of quinone and hydroquinone in acetonitrile. Our results provide a fundamental guide for determining the adequate amount of buffer for the electrochemical investigation of PCET reactions.