A novel π-d conjugated cobalt tetraaza[14]annulene based atomically dispersed electrocatalyst for efficient CO2 reduction

16 pages. -- Scheme S1. Scheme of the synthesis of Co-TAA. -- Figure S1. FT-IR spectra of the model compound Co-TAA, and Poly-TAA-Co powder. -- Figure S2. (a-b) HRTEM images and (c-d) STEM images of Poly-TAA-Co. -- Figure S3. EELS chemical composition maps from the red squared area of the STEM \nmicrograph. Individual Co L2,3-edges at 779 eV (red), N K-edges at 401 eV (green), O K-edges at 532 eV (blue), and C-K edges at 284 eV (grey) and composites of Co-N, Co-O, Co-C, N-O and Co-N-C. -- Figure S4. (a)-(b) Survey, high resolution C1s XPS spectra of Poly-TAA powder, respectively. -- Figure S5. (a) Survey, high resolution C1s XPS spectra of Poly-TAA-Co powder, respectively. -- Figure S6 TGA analysis of Poly-TAA-Co under argon by heating to 600 ℃ at the rate of 5 ℃/min. -- Table S1. Co K-edge EXAFS fitting parameters for Poly-TAA-Co. -- Figure S7. N2 adsorption and desorption of Poly-TAA (a), Poly-TAA-Co (b) and \nPoly-TAA-Co-CNT (c), respectively. -- Figure S8. (a) Total current density of Poly-TAA-Co-CNT (7:3). (b) FE of CO and H2 at various potentials for Poly-TAA-Co-CNT (7:3). -- Figure S9 Current density for H2 production on Poly-TAA-Co-CNT(1:1) and Poly-TAA-Co-CNT(3:7). and. -- Figure S10. Nyquist plots of the electrochemical impedance spectroscopy (EIS) data of (a) Poly-TAA-Co, (b) Poly-TAA-Co-CNT(1:1) and Poly-TAA-Co-CNT(3:7) \nelectrodes after the activation process. -- Figure S11. Linear sweep voltammetry (LSV) curves of (a) Poly-TAA-Co. -- Figure S12. FE of H2 at various potentials on Co-TAA-CNT(3:7), CoPc-CNT(3:7) and Poly-TAA-Co-CNT(3:7). -- Figure S13. XRD patterns of Poly-TAA-Co-CNT loaded on carbon paper before and after CO2RR. -- Figure S14 HAADF-STEM (a, c), BF-TEM (b, d) and HRTEM micrographs (c, e) of Poly-TAA-Co-CNT (3:7) sample (before and after CO2RR). -- Figure S15. EELS chemical composition maps obtained from the red squared area of the STEM micrograph. Individual Co L2,3-edges at 779 eV (red), N K-edges at 401 eV (green), O K-edges at 532 eV (blue), and C-K edges at 284 eV (grey) and composites of Co-N, Co-O, Co-C, N-O and Co-N-C. (Poly-TAA-Co-CNT (3:7), after electrocatalytic CO2RR). -- Figure S16. Calculated energy diagrams for CO2 to CO at －0.5 V conversion on CoPc and CoTAA molecule, respectively. -- Table S2. The comparison of electrochemical reduction of CO2 to CO for reported cobalt based electrocatalysts.