Elucidating the Reaction Pathway of Glucose Electrooxidation to Its Valuable Products: The Influence of Mass Transport and Electrode Potential on the Product Distribution

Converting glucose electrochemically to its valuable derivatives, gluconic and glucaric acids, is a promising process for the utilization of renewable carbon sources. Understanding the reaction pathway to form glucaric acid from glucose is key to performing the process efficiently. In this study, we investigate the influence of mass transport as well as electrode potential on the product distribution in glucose, gluconic acid, and glucuronic acid oxidation on a gold disk in an RDE setup. We find glucose and glucuronic acid to be easily oxidized, while the oxidation of gluconic acid is kinetically limited. Combining DFT calculations and the experimental results, we show that on gold, the oxidation of aldehyde groups proceeds readily, while the oxidation of hydroxyl groups is challenging and occurs indiscriminately on C atoms in glucose and its derivatives. Additionally, the DFT calculations present a reaction pathway that can explain the absence of glucuronic acid in the conducted experiments.