Covalent modified LDH electrocatalyst for enhanced electrocatalytic oxidation of KA oil to adipic acid

Abstract

Adipic acid plays a crucial role as a key constituent of polymers. The electrocatalytic strategy of KA oil (cyclohexanol and cyclohexanone) electrooxidation has been recognized as an effective way to produce adipic acid compared to the commercial thermocatalytic oxidation method using corrosive nitric acid and producing nitrous oxide. Herein, we report a ligand covalent modification strategy to enhance the current density of KA oil electrooxidation by NiMn-LDH modified with dodecyl triethoxysilane (NiMn-LDH-DTES) via a silanization reaction. For example, NiMn-LDH-DTES exhibits 1.7-fold current density for cyclohexanol electrooxidation compared to pure NiMn-LDH. The cyclohexanol conversion rate and H₂ production rate reach 0.044 mmol cm⁻² h⁻¹ and 43.2 mL cm⁻² h⁻¹ at 1.52 V vs. RHE, which are 1.7- and 1.5-fold higher than those of NiMn-LDH, respectively. And at high cyclohexanol conversion of 96.2%, the yield of adipic acid reaches 79.4% with FE of 83.4% and selectivity of 94.4%. NiMn-LDH-DTES demonstrated its efficiency for cyclohexanone oxidation with enhanced performance. We confirmed that the modification of NiMn-LDH by DTES can promote the generation and exposure of more reactive sites, and also facilitates the adsorption of KA oil, thus enabling the high reaction rate.