fig5

Figure 5. (A) Strategies for synthesizing Cu NC, Cu MNC, and Cu MNC-x. This figure is quoted with permission from Xue et al.^[49]; (B) Synthesis routes for Cu-N-C-T. This figure is quoted with permission from Zhu et al.^[47]; (C) Schematic illustration of the synthetic procedure of Cu-N-C. This figure is quoted with permission from Chen et al.^[41]; (D) Schematic illustration of FeSAs/g-C₃N₄ synthesis. This figure is quoted with permission from Song et al.^[57]; (E) Strategy for synthesizing Cu-N₃ SACs/NCNT. This figure is quoted with permission from Wang et al.^[50]; (F) Schematic illustration of the synthesis of Ni₁Cu-SAA. This figure is quoted with permission from Cai et al.^[73].