Screening Nitrogen-Coordinated Single Atom Catalysts on Armchair Carbon Nanotubes for Enhanced Electrochemical CO2 Reduction to C1 Products

Single atom catalysts (SACs) are widely used in electrocatalytic reactions due to their superior stability and selectivity. The electrochemical reduction of carbon dioxide (eCO2R) has garnered significant attention in recent years due to the global warming crisis and its potential as a route for the utilization of CO2. However, eCO2R is still limited by low activity, poor selectivity, and an elusive reduction mechanism. In this work, the reduction of CO2 to C1 products catalyzed by nitrogen-coordinated SACs supported on armchair carbon nanotubes (SAC–CNTs) is investigated using a protocol combining density functional theory and machine learning simulations to predict the thermodynamic and electrochemical stability, as well as the catalytic performance of SAC–CNTs toward eCO2R. Our analysis also included the effects of surface curvature and axial strain of the CNTs on catalytic performance. The results indicate that Cr–N4–CNT and Co–N4–CNT exhibit enhanced selectivity toward CH4 and CH3OH, while Zn–N4–CNT is the best candidate for formic acid formation. Both surface curvature and axial strain influence the relative position of the metal atom on the CNT surface, thereby modulating the catalytic activity.