Atomically Dispersed Manganese on Carbon Substrate for Aqueous and Aprotic CO 2 Electrochemical Reduction.

CO ₂ utilization and conversion are of great importance in alleviating the rising CO ₂ concentration in the atmosphere. Here, a single-atom catalyst (SAC) is reported for electrochemical CO ₂ utilization in both aqueous and aprotic electrolytes. Specifically, atomically dispersed Mn-N ₄ sites are embedded in bowl-like mesoporous carbon particles with the functionalization of epoxy groups in the second coordination spheres. Theoretical calculations suggest that the epoxy groups near the Mn-N ₄ site adjust the electronic structure of the catalyst with reduced reaction energy barriers for the electrocatalytic reduction of CO ₂ to CO. The resultant Mn-single-atom carbon with N and O doped catalyst (MCs-(N,O)) exhibits extraordinary electrocatalytic performance with a high CO faradaic efficiency of 94.5%, a high CO current density of 13.7 mA cm ^-2 , and a low overpotential of 0.44 V in the aqueous environment. Meanwhile, as a cathode catalyst for aprotic Li-CO ₂ batteries, the MCs-(N,O) with well-regulated active sites and unique mesoporous bowl-like morphology optimizes the nucleation behavior of discharge products. MCs-(N,O)-based batteries deliver a low overpotential and excellent cyclic stability of 1000 h. The findings in this work provide a new avenue to design and fabricate SACs for various electrochemical CO ₂ utilization systems.
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