Electrochemical C–N Bond Formation within Boron Imidazolate Cages Featuring Single Copper Sites
Carter S. Gerke, Yuting Xu, Yuwei Yang, Gregory D. Foley, Briana Zhang, Ethan Shi, Nicholas M. Bedford, Fanglin Che, V. Sara Thoi
Abstract
Electrocatalysis expands the ability to generate industrially relevant chemicals locally and on-demand with intermittent renewable energy, thereby improving grid resiliency and reducing supply logistics. Herein, we report the feasibility of using molecular copper boron-imidazolate cages, BIF-29(Cu), to enable coupling between the electroreduction reaction of CO 2 (CO 2 RR) with NO 3 – reduction (NO 3 RR) to produce urea with high selectivity of 68.5% and activity of 424 μA cm –2 . Remarkably, BIF-29(Cu) is among the most selective systems for this multistep C–N coupling to-date, despite possessing isolated single-metal sites. The mechanism for C–N bond formation was probed with a combination of electrochemical analysis, in situ spectroscopy, and atomic-scale simulations. We found that NO 3 RR and CO 2 RR occur in tandem at separate copper sites with the most favorable C–N coupling pathway following the condensation between *CO and NH 2 OH to produce urea. This work highlights the utility of supramolecular metal–organic cages with atomically discrete active sites to enable highly efficient coupling reactions.