Steering C-N coupling pathway on spatial-separated zinc dual sites for efficient oxime electrosynthesis

Abstract

Multi-step cascade reactions that couple electrochemical and non-electrochemical steps are an appealing strategy for designing efficient reactions. However, their development is fundamentally constrained by mechanistic uncertainty, leading to uncontrolled side reactions. Herein, a spatially separated active-site strategy is developed, using the electrosynthesis of cyclohexanone oxime (CHO) as a model, to bias the reaction toward the interface confinement pathway via a designed Zn-based mixed-site catalyst. Based on controlled experiments, in situ characterization and theoretical calculations, we demonstrate that the Zn single-atom and Zn nanoparticle site can adsorb N-containing intermediates and cyclohexanone (CYC), respectively. It is demonstrated that 99.5% cyclohexanone conversion, 50.3% cyclohexanone oxime Faradaic efficiency, 100% carbon selectivity, and 41.0% nitrogen selectivity can be achieved, while maintaining performance stability over 200 h. Detailed mechanistic analysis indicates that at suitable Zn single-atom and nanoparticle ratio, interfacial hydrogen-bond network of water is optimized, which can modulate both adsorption orientation and coverage of *CYC and the coverage of N-containing intermediates to enhance the desired reaction pathway. Multistep electrochemical reactions are limited by unstable intermediates and competitive adsorption at catalytic sites. Here, the authors report spatially separated zinc sites which steer interfacial C-N coupling and enable selective and stable oxime electrosynthesis from nitrate and cyclohexanone.