One-Pot Electrochemical Synthesis of (Hydroxyamino)methanesulfonate from CO₂, Nitrate/Nitrite, and Sulfite

Carbon-heteroatom (C-X, X = N, S, P, etc.) coupling represents a promising strategy to diversify the product scope of the electrocatalytic CO₂ reduction reaction (eCO₂RR). To date, most studies have focused on single C-X bond formation between CO₂ and one heteroatom source in one electrochemical reaction. The formation of multiple C-X bonds in eCO₂RR remains largely unexplored due to the inherent complexity of multicomponent and multistep reaction pathways. Herein, we report, for the first time, the formation of multiple C-X bonds in eCO₂RR, where (hydroxyamino)methanesulfonate (HAMS), a compound containing both C-N and C-S bonds, is synthesized via electroreduction of CO₂ in an electrolyte solution containing nitrate/nitrite (NO₃^-/NO₂^-) and sulfite (SO₃^2-) using a cobalt phthalocyanine supported on the carbon nanotube (CoPc/CNT) catalyst. Mechanistic studies and theoretical calculations reveal that the formation of HAMS proceeds via C-N coupling followed by C-S bond formation. By adjusting the electrolyte composition, the maximum faradaic efficiency of 5.8% and the highest partial current density of -2.4 mA cm^-2 were achieved for HAMS. This work demonstrates a rare one-pot electrosynthesis of products with multiple C-X bonds (i.e., involving both C-N and C-S coupling) and provides a new route toward constructing functionally complex molecules from simple, abundant precursors.