(A) Schematic illustration of the synthesis process, and (B) SEM image of TCN(NH₃). (C) Photocatalytic CO₂ reduction performance. (D) Adsorption and desorption energies based on DFT calculations. Adapted with permission from [137]. Copyright 2019, Elsevier. (E) HAADF-STEM of Cu/CN. (F) FT-EXAFS, and XANES of the Cu K-edge. (H) Free energy diagram of CO₂ reduction. (I) Photocatalytic CO₂ reduction activity of Cu/CN. Adapted with permission from [138]. Copyright 2020, American Chemical Society.