Evaluation of Active Oxygen Species Derived from Water Splitting for Electrocatalytic Organic Oxidation

Active oxygen species (OH*/O*) derived from water electrolysis are essential for the electrooxidation of organic compounds into high-value chemicals, which can determine activity and selectivity, whereas the relationship between them remains unclear. Herein, using glycerol (GLY) electrooxidation as a model reaction, we systematically investigated the relationship between GLY oxidation activity and the formation energy of OH* (ΔG_OH*). We first identified that OH* on Au demonstrates the highest activity for GLY electrooxidation among various pure metals, based on experiments and density functional theory, and revealed that ΔG_OH* on Au-based alloys is influenced by the metallic composition of OH* coordination sites. Moreover, we observed a linear correlation between the adsorption energy of GLY (E_ads) and the d-band center of Au-based alloys. Comprehensive microkinetic analysis further reveals a volcano relationship between GLY oxidation activity, the ΔG_OH* and the adsorption free energy of GLY (ΔG_ads). Notably, Au₃Pd and Au₃Ag alloys, positioned near the peak of the volcano plot, show excellent activity, attributed to their moderate ΔG_OH* and ΔG_ads, striking a balance that is neither too high nor too low. This research provides theoretical insights into modulating active oxygen species from water electrolysis to enhance organic electrooxidation reactions.