Activating the Ni‐Contenting Carbon Nanotube by Covalent Triazine Frameworks to Form Atomically Dispersed Ni Sites with Curvature Effect for Electrocatalytic CO2 Reduction

N‐coordinated Ni sites (NiN x ) are effective catalysts for the electrochemical reduction of CO 2 to CO. In most researches, modulating the coordination environment of Ni atoms is focused on to improve electrochemical CO 2 reduction (ECR) performance. However, the influence of the carbon substrate's structure on the intrinsic activity of NiN x is seldom investigated. The highly curved surface of carbon nanotubes (CNT) may provide a unique curvature effect on NiN x . It is found that the Ni residues in CNT can be atomized to form NiN x sites on the surface of CNT (Ni‐N/CNT@covalent triazine framework [CTF]) through high‐temperature pyrolysis, using a soluble CTF nanosheet as N precursor. The π‐conjugated and ultrathin 2D structure of CTF enables closer interfacial contact between CTF and CNT, which avoids the formation of a thick carbon layer to maximize the curvature effect. Theoretical data reveal that the NiN 3 configuration may act as a highly active ECR site, and the curvature effect from CNT can further tune the electronic structure of NiN 3 , thus improving the ECR kinetics. The Ni‐N/CNT@CTF‐based flow‐cell electrolyzer exhibits a j CO of 201 mA cm −2 at −0.9 V with a high FE CO of 98%.