Interface Engineering Induced by Potassium-Intercalated Graphite on Co3O4 for Selective Electrooxidation of Glycerol into Glycolate

Transforming glycerol into glycolic acid through electrocatalysis offers a strategy for valorizing surplus glycerol and alleviating the energy dilemma. However, it remains challenging to precisely control the oxidation of the hydroxyl functional group and the fracture of the C–C bond. Herein, we develop an interface engineering strategy utilizing potassium graphite intercalation compounds (K-GIC) to modulate Co₃O₄, achieving significantly enhanced performance in producing glycolate from the electrocatalytic glycerol oxidation reaction (GOR). Specifically, the interfacial charge transfer from electron-rich KC_x to Co₃O₄ increases the electronic density of Co and O atoms. Meanwhile, more oxygen vacancies were generated on Co₃O₄ due to the electronic effect and lattice distortion. Consequently, the markedly enhanced adsorption capacities and modulated adsorption ratio of glycerol and reactive oxygen species OH^– are determined on the catalytic interface. As a result, while the surface catalytic activity is enhanced, the deep oxidation of glycerol and secondary C–C cleavage are weakened, which is beneficial for the generation of glycolate. In situ attenuated total reflection surface-enhanced infrared absorption spectroscopy (ATR-SEIRAS) and density functional theory (DFT) calculations further unlock the decrease in the energy barrier in the pathway toward glycolate. The KC_x-Co₃O₄ exhibits high glycolate selectivity and faradaic efficiency, reaching 44% and 37%, respectively, with a glycerol conversion of 97%. This work provides practical guidance for interface engineering in designing catalysts for value-added glycerol electrooxidation.