High-Density Edge-Hosted Ni Single Atoms on Nanoscale Carbon for Boosting Electrocatalytic CO₂ Reduction

Edge-hosted single-atom sites provide asymmetric charge distribution compared with in-plane sites, showing higher intrinsic activity. However, traditional preparation methods for edge sites rely on creating mesopores by etching, making it difficult to obtain high-density edge sites. Herein, it is demonstrated that reducing the size of carbon support to the nanoscale by a nanocasting approach enables high-density edge-hosted single-atom sites, significantly enhancing the catalytic performance in electrochemical CO₂ reduction. To achieve this, edge Ni sites on N-doped carbon (e-Ni/NC) with an average size of 26 nm are prepared by calcination of ZIF-L confined within SBA-16. e-Ni/NC achieves a CO current density of 480.4 mA cm^-2 and a CO Faradaic efficiency over 90.0% from -0.6 to -1.6 V, which are superior to the in-plane Ni sites on N-doped carbon. The Zn-CO₂ battery with e-Ni/NC cathode possesses a maximum power density of 1.2 mW cm^-2 and shows stable performance in galvanostatic charge-discharge cycling.