fig3

Figure 3. (A) The LSV curves of COP_MCT-Co-X (X represent pyrolysis temperature) catalysts at different temperatures; (B) E_1/2 of COP_MCT-Co-X catalysts at different temperatures; (C) Tafel plots of COP_MCT-Co-X; (D) The CV curves of COP_MCT-Co-900; (E) The LSV curves of COP_MCT-Co-900, COP_MCT-Ni-900, COP_MCT- 900 and COP_MCT-Fe-900; (F) Tafel plots of COP_MCT-Co-900, COP_MCT-Ni-900, COP_MCT- 900 and COP_MCT-Fe-900. LSV: Linear sweep voltammetry; COP: covalent organic polymer; CV: cyclic voltammetry.