Oxygen-tolerant CO2 electroreduction over covalent organic frameworks via photoswitching control oxygen passivation strategy

1. The structure and characterization of open-DAE-BPy-CoPor. a Comparison of the experimental powder X-ray diffraction pattern with simulated PXRD patterns. b Solid-state 13C NMR spectrum. c N2 sorption isotherms (Inset: pore width distribution). d Transmission electron microscopy and e high resolution transmission electron microscopy images. f Fast Fourier transformation, high resolution transmission image and lattice distance. g Aberration-corrected high-angle annular dark-field scanning transmission electron microscopy image and h-i energy-dispersive X-ray spectroscopy elemental mapping.
2. The local coordination structure. a Co K-edge of X-ray absorption near-edge structure spectra of open-DAE-BPy-CoPor, Co foil, CoO, and Co3O4. b Co K-edge of EXAFS spectra of open-DAE-BPy-CoPor, Co foil, Co-TPPCN, Co3O4 and CoO. c The extended X-ray absorption fine structure fitting curves of open-DAE-BPy-CoPor
3. The characterization of close-DAE-BPy-CoPor. a Comparison of the PXRD patterns of open-DAE-BPy-CoPor and close-DAE-BPy-CoPor. b The N2 sorption isotherms and pore size distribution of close-DAE-BPy-CoPor. c and d the X-ray photoelectron spectroscopy of S 2p region for open-DAE-BPy-CoPor and close-DAE-BPy-CoPor.
4. The electrocatalytic CO2RR performances. a Linear sweep voltammetry curves curves, b the CO Faradic efficiency and c the CO partial current density of the BPy-CoPor, close-DAE-BPy-CoPor and open-DAE-BPy-CoPor. d Stability of close-DAE-BPy-CoPor at -0.7 V vs. RHE. All the above tests were conducted in a CO2-saturated 0.5 M KHCO3 aqueous solution under dark environment. e The CO Faradic efficiency of BPy-CoPor, open-DAE-BPy-CoPor, close-DAE-BPy-CoPor, COF-366(Co) and Co-TAPP under aerobic conditions. f The CO partial current density of the BPy-CoPor, close-DAE-BPy-CoPor and open-DAE-BPy-CoPor in the co-feeding CO2 and 5% O2.
5. Density functional theory calculations and proposed schematic mechanism. a Free energy diagrams of close-DAE-BPy-CoPor and open-DAE-BPy-CoPor for CO2RR and HER pathways. b The Bader charge analysis of different Co atoms in close-DAE-BPy-CoPor and open-DAE-BPy-CoPor (inset: the calculation intermediate models of the CO2RR). c Projected density of states and integrated density of states of adsorption structures of O2 on close-DAE-BPy-CoPor and open-DAE-BPy-CoPor. d Proposed schematic mechanism for the CO2RR on close-DAE-BPy-CoPor under aerobic conditions