Integrated CO ₂ Capture and Conversion Induced by Amines for Effective Electrocatalytic N‐Methylation

Abstract

ABSTRACT N‐Methylation of amines is a crucial transformation for synthesizing valuable compounds. However, conventional N‐methylation methods often rely on hazardous reagents. The electroreduction of CO 2 as a sustainable C1 source presents an attractive alternative. Nevertheless, the direct electrochemical activation of CO 2 requires high overpotentials, often leading to a low Faradaic efficiency (FE). This study presents a CO 2 capture‒conversion pathway for the N‐methylation of amines. High concentrations of nucleophilic piperidine preferentially capture CO 2 , enabling spontaneous C─N coupling, as confirmed by 13 C nuclear magnetic resonance spectroscopy. Moreover, N ‐methyl piperidine (NMP) is produced through an electroreduction process. In situ Raman spectroscopy and theoretical calculations reveal the formation of a key piperidinium intermediate and provide insights into its role in subsequent electroreduction. This pathway effectively suppresses side reactions typical of CO 2 electroreduction, achieving a high NMP FE of 71.6% at −0.6 V versus Ag/AgCl. Furthermore, the CO 2 capture‒conversion pathway produces various N‐methylated amines, such as dimethylamine and 1‐methyl ethylenediamine, with excellent FEs, highlighting the generality and advantages of this approach.