Curvature-dependent activity of CO2 electrocatalytic reduction on NCNT@Ni

The impact of carbon material curvature is often underestimated in studies of carbon-based electrocatalysts for the CO 2 reduction reaction (CO 2 RR). To clarify its role, we tuned the diameter of nitrogen-doped carbon nanotube (NCNT) by controlling the size of embedded Ni nanoparticles (50 to 120 nm), in which the Ni-modified C-N species has been identified as an efficient site for CO 2 RR to CO. We found that the FE CO and TOF increase with the curvature of NCNT, particularly in the high potential window that is the diffusion-limited region. This enhancement is attributed to accelerated CO desorption since the electrophobic nature of high-curvature C-N defects reduces hybridization between *CO and active sites. These insights highlight curvature engineering as a promising strategy to enhance CO current density in carbon-based electrocatalysts.