CeO2 Modification Promotes the Oxidation Kinetics for Adipic Acid Electrosynthesis from KA Oil Oxidation at 200 mA cm-2.

Electrocatalytic oxidation of cyclohexanol/cyclohexanonein water provides a promising strategy for obtaining adipic acid (AA), which is an essential feedstock in the polymer industry. However, this process is impeded by slow kinetics and limited Faradaic efficiency (FE) due to a poor understanding of the reaction mechanism. Herein, NiCo2O4/CeO2 is developed to enable the electrooxidation of cyclohexanol to AA with a 0.0992 mmol h-1 cm-2 yield rate and 87% Faradaic efficiency at a lower potential. Mechanistic investigations demonstrate that cyclohexanol electrooxidation to AA is a gradual oxidation process involving the dehydrogenation of cyclohexanol to cyclohexanone, the generation of 2-hydroxy cyclohexanone, and subsequent C-C cleavage. Theoretical calculations reveal that electronic interactions between CeO2 and NiCo2O4 decrease the energy barrier of cyclohexanone oxidation to 2-hydroxy cyclohexanone and inhibit the *OH to *O step, leading to AA electrosynthesis with a high yield rate and FE. Kinetic analysis further elucidates the effect of CeO2 on promoting cyclohexanone adsorption and activation on the electrode surface, thus facilitating the reaction kinetics. Moreover, a two-electrode flow reactor is constructed to produce 72.1 mmol AA and 10.4 L H2 by using KA oil as the anode feedstock at 2.5 A (200 mA cm-2), demonstrating promising potential.