Pulsed electrosynthesis orthogonally optimizes C‒N coupling and hydrogenation for amine production with a molecular catalyst

Abstract

Abstract Co-electrolysis of CO 2 and nitrate offers a sustainable route to organic amines but suffers from a kinetic mismatch between C-N coupling and hydrogenation steps under static conditions. This mismatch is challenging to address through conventional catalyst design and therefore limits both efficiency and selectivity. Here, we introduce a pulsed strategy that orthogonally decouples these steps by alternating optimized potentials. Pulses at less reductive potentials suppress hydrogenation and thus favor oxime formation, whereas more reductive potentials promote hydrogenation to amines. Using cobalt phthalocyanines, this approach triples the reaction rate and doubles the selectivity for methylamine compared to static methods, and also enables the formation of higher amines. In situ studies and density functional theory calculations reveal that a more reductive pulse accelerates hydrogenation, promoting a multielectron cascade through intermediates. Retrosynthetic analysis and product distribution trends further support a sequential coupling-hydrogenation pathway from methylhydroxylamine/methylamine to higher amines. This work offers a framework for steering multistep C–N bond formation and shows how dynamic electrochemistry can turn waste-derived carbon and nitrogen into valuable products.