In Situ Coordination Engineering of Fe Single Atoms Enables Efficient Electrocatalytic Cyclohexanone Oxime Synthesis.
Abstract
Cyclohexanone oxime (CHO) is a vital precursor in industrial synthesis of nylon-6. However, traditional synthetic routes involve harsh reaction conditions and the potential danger posed by explosive hydroxylamine. Herein, we introduce an electrocatalytic approach for CHO synthesis via the reductive coupling of cyclohexanone (CYC) and nitrite using an electrocatalyst (FeNP@FeSA-N(OH)-B-C), which features a synergistic modulation of Fe single atoms (Fe SAs) by axial coordinated OH, second-shell coordinated boron (B), and adjacent Fe nanoparticles on a nitrogen-doped carbon support. In a membrane electrode assembly electrolysis cell, the FeNP@FeSA-N(OH)-B-C achieves a Faradaic efficiency for CHO of 63.97% and a CHO yield rate of 0.629 mmol h-1 cm-2 at 100 mA cm-2, maintaining exceptional stability over 110 h of continuous operation. In situ characterizations reveal formation of electron-deficient Fe SAs with a Fe-N(OH)-B structure. Density functional theory calculations demonstrate that Fe-N(OH)-B facilitates the *NO → *NOH → *NHOH → *NH2OH reaction pathways while it inhibits *NH2OH reduction to NH3, collectively promoting the activity and selectivity of electrochemical CHO synthesis. This work not only presents a highly efficient and stable electrocatalyst for sustainable CHO synthesis but also provides insights into the dynamic control of coordination environment of SAs for enhanced electrocatalytic performance.