Electrocatalytic synthesis of methylamine from nitrate and carbon dioxide on a heterometallic polyphthalocyanine.

Electrocatalytic coreduction of nitrate and CO provides an opportunity for the synthesis of organonitrogen chemicals. The major challenge is to realize the simultaneous reduction of nitrate and CO into active intermediates for C-N bond formation. In this work, methylamine is synthesized from nitrate and CO on a polyphthalocyanine electrocatalyst with heterometal centers (CoCuPPc). Notably, it is found that the Co and Cu centers coordinated with the conjugated macrocyclic network of polyphthalocyanine can catalyze CO reduction to formaldehyde and nitrate reduction to hydroxylamine, respectively. The nucleophilic attack of hydroxylamine on formaldehyde generates a formaldoxime intermediate, which is then further reduced to methylamine. The overreduction reactions of hydroxylamine and formaldehyde intermediates are suppressed by CoCuPPc. This bifunctional catalyst with heteronuclear active centers simultaneously catalyzes nitrate and CO reduction to key intermediates for C-N bond formation.