A Bipolar Integrated Electro-Chemocatalysis System for Continuous-Flow Paired Synthesis of Cyclohexanone Oxime at Industrial-Relevant Current Density.

Abstract

ε-Caprolactam production critically depends on cyclohexanone oxime (CHO), yet its sustainable synthesis remains constrained by the handling and utilization of hydrogen peroxide (H₂O₂). Here, we developed a bipolar integrated electro-chemocatalysis system (BIECS) that enables continuous-flow paired CHO synthesis under ambient conditions with unprecedented efficiency. Using oxygen-vacancy-enriched bismuth oxide nanofibers as a bifunctional electrocatalyst, the system simultaneously drives the two-electron oxygen reduction and water oxidation reactions at the cathode and anode, respectively, achieving remarkable cell Faradaic efficiencies up to 165% for H₂O₂ production, which then on-site reacts with cyclohexanone and NH₃ over titanium silicon-1 with near-unity selectivity. Consequently, the BIECS delivers remarkable apparent electron efficiency of 120%-160% for cascade CHO production and achieves an exceptional productivity of up to 5.04 mmol h^-1 cm^-2 at industrial-relevant current density with excellent stability over 150 h for continuous-flow electrolysis. Combined experimental and theoretical studies reveal that the oxygen vacancies of the catalyst modulate the adsorption energetics and configuration of the key OOH^* intermediate, thereby promoting highly selective two-electron pathways at both electrodes and enhancing the cascade ammoximation kinetics. This work establishes a scalable strategy that integrates paired electrocatalytic H₂O₂ synthesis with chemocatalytic ammoximation, providing a highly efficient platform for sustainable CHO production.