Unraveling the Thermocatalytic and Electrocatalytic Pathways of Glucose Oxidation on Gold Surfaces Using Atomically Precise Au25 Nanoclusters

The performance of electrochemical glucose oxidation has been overestimated due to a lack of understanding of the interactions between the catalyst surface and glucose. Herein, we unravel the mechanisms of glucose oxidation using atomically well-defined Au₂₅ nanoclusters, exhibiting exceptional activity while maintaining structural integrity. The oxidation reactivity is significantly influenced by applied potential and accordingly altered chemical state of the Au surface, with three distinct mechanisms leading to dominance at different potential regions: an aerobic oxidation pathway near open-circuit, a 1e^– electrocatalytic pathway prevailing at low potentials, and a typical 2e^– electrocatalytic pathway dominating at higher potentials. The aerobic pathway involves coupling glucose oxidation with an O₂ reduction, producing gluconic acid and H₂O₂, respectively, without an applied potential. In the 1e^– pathway, the α-hydrogen of glucose is stripped by the Au surface, resulting in a simultaneous production of gluconic acid and H₂ at the anode. Unveiling these pathways enabled the precise evaluation of performance as 100% Faraday efficiency across all potential ranges. Our findings provide a definitive framework for elucidating the structure–activity relationship in the electrocatalysis of biomass.