The report is mainly from four aspects: At the first aspect, we will focus on the role of anion in electroreduction of CO2. We present the first example of CO2 electroreduction catalyst that features charged imidazolium groups in the porphyrin-based COF (Co-iBFBim-COF), in which the free anions (e.g., F−, Cl−, Br−, I−, and PF6−) of imidazoliums nearby active metal sites can improve CO2RR selectivity and energy conversion efficiency via hydrogen bonds between the anions and the key intermediate *COOH. Moreover, the Tafel slopes, operando infrared spectroscopy, and DFT calculations reveal that the key intermediate *COOH involved in the pathway of CO formation could be stabilized by hydrogen bonding with the free ions in the cationic COFs. In the second part, we will pay attention on the role of light in electroreduction of CO2. We will report a series of visible-light sensitive cobalt porphyrin-based COFs (denoted as Co-BPY-COF-RuX) containing active centers (porphyrin Co) and photosensitizers (Ru(BPY)3) in the crystalline COFs material, which have a strong built-in electric field and thus exhibit excellent CO2 conversion ability. The theoretical and experimental work confirmed that the built-in electric field in the Co-BPY -COF-RuX is a key factor in triggering photocoupled CO2RR. Meanwhile, the catalytic kinetics studies elucidate that the synergistic effect of the built-in electric field and visible light is the primary responsibility for facilitating the first electron transfer to form *COO- species. In the third part, we are interested in using stable and conductive copper thiol-based MOFs to electroreduce CO2 into deep reduction products and reveal the structure-activity relationship. Herein, we have designed synthesize a d-π conjugated and conductive thiol-based MOF, which showing 64% CH4 selectivity at 280 mA/cm2. Meanwhile, Operando-X-ray absorption spectroscopy revealed that the Cu-S4C1 structure gradually appeared in the electrochemical process, and after stopping electrolysis, the Cu-S4 structure was restored. It is demonstrated that Cu-S4 is maintained after electrochemical reconstruction and that is behaves as an active site.

2D covalent/metal organic frameworks for efficient CO2 electroreduction

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ACS Fall 2022

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