The electrochemical reduction of carbon dioxide is an appealing technology that stores renewable electricity in the chemical form and has the potential to transform the way carbon fuels are utilized today. While there have been successes in the electrosynthesis of alkanes, alkenes and alcohols, access to organonitrogen molecules such as alkylamines remains largely beyond the reach of current electrocatalysis. Here we report the first electrochemical reaction that converts carbon dioxide and nitrate to methylamine in aqueous media under ambient conditions catalysed by a cobalt β-tetraaminophthalocyanine molecular catalyst supported on carbon nanotubes. The overall reaction, involving the transfer of 14 electrons and 15 protons to form each methylamine molecule, is an eight-step catalytic cascade process enabled by the coupling of two reactive intermediates near the catalyst surface. The key C–N bond-forming step is found to be the spillover of hydroxylamine from nitrate reduction and its subsequent condensation with formaldehyde from carbon dioxide reduction. This study provides a successful example of sustainable alkylamine synthesis from inorganic carbon and nitrogen wastes, which could contribute to greenhouse gas mitigation for a carbon-neutral future.

二氧化碳的电化学还原是一种吸引人的技术，该技术以化学形式存储可再生电力，并有可能改变当今使用碳燃料的方式。尽管在烷烃，烯烃和醇的电合成方面取得了成功，但获得有机氮分子（如烷基胺）的途径仍然远远超出了当前的电催化能力。在这里，我们报告了第一个电化学反应，该反应在环境条件下由负载在碳纳米管上的钴β-四氨基酞菁钴分子催化剂催化，将二氧化碳和硝酸盐在水性介质中转化为甲胺。整个反应涉及转移14个电子和15个质子以形成每个甲胺分子，是通过在催化剂表面附近偶联两个反应性中间体而实现的八步催化级联过程。发现关键的C–N键形成步骤是硝酸盐还原过程中羟胺的溢出以及随后与二氧化碳还原过程中甲醛的缩合。这项研究为从无机碳和氮废物中可持续合成烷基胺提供了成功的范例，这可能有助于减少碳中和未来的温室气体。