Multiple Secondary Bond-Mediated C-N Coupling over N-Doped Carbon Electrocatalysts.

Abstract

Electrocatalytic C-N reductive coupling offers a sustainable and eco-friendly approach to producing value-added oximes. The challenge lies in the overstrong chemisorption of N-containing intermediates and carbonyl compounds on metal-based catalysts, which causes low Faradaic efficiency and yield rates, as well as undesired byproducts. Here, we propose a multiple secondary bond-mediated strategy for C-N coupling toward benzaldoxime on a nitrogen-doped graphene-like carbon catalyst (NC). Integrating theoretical and experimental analyses, we demonstrate that the graphitic-N-C sites in NC promote nitrite reduction into hydroxylamine via weak electrostatic interaction. Moreover, the hydrogen bonds and π-π stacking interactions among NC, hydroxylamine, and benzaldehyde synergistically enrich the key intermediates on the catalyst surface and inhibit the side reactions, leading to a highly selective C-N coupling process. Remarkably, the NC catalyst achieves a high Faradaic efficiency of 73 ± 1% and a yield rate of 6.8 ± 0.1 mol h^-1 m^-2 for benzaldoxime electrosynthesis at an economically viable current density of 0.1 A cm^-2, as revealed by technoeconomic analysis. Our results demonstrate an appealing route for high-performance C-N coupling with enhanced economic feasibility.