Do the Hydrogen\nEvolution Reaction and Oxygen Reduction\nReaction Really Need To Be Suppressed in O<sub>2</sub>‑Tolerant\nCO<sub>2</sub> Electroreduction Catalyzed by DAE-BPy-CoPor and Co-TAPP?

This letter chooses DAE-BPy-CoPor [DAE, 1,2-bis(5′-formyl-2′-methylthien-3′-yl)cyclopentene;\nBPy, 2,2′-bipyridine-5,5′-dicarbaldehyde; and CoPor,\ntwo-dimensional cobalt porphyrin-based covalent organic framework]\nand Co-TAPP [10,15,20-tetrakis(4-aminophenyl)porphinatocobalt] as\ntwo model catalysts to investigate the effect of the hydrogen evolution\nreaction (HER) and oxygen reduction reaction (ORR) in the O<sub>2</sub>-tolerant CO<sub>2</sub> electroreduction reaction (CO<sub>2</sub>RR). Both catalysts have been proven to have CO<sub>2</sub>RR activity\nat a potential range from −0.60 to −1.10 V when CO<sub>2</sub> and O<sub>2</sub> are co-feeding (Zhu, H.-J.; Si, D.-H.; Guo, H.; Chen, Z.; Cao, R.; Huang, Y.-B. Oxygen-tolerant CO<sub>2</sub> electroreduction over covalent organic frameworks via photoswitching\ncontrol oxygen passivation strategy. Nat.\nCommun. 2024, 15, 1479, DOI: 10.1038/s41467-024-45959-9). The calculated results\nby grand canonical density functional theory (GC-DFT) and microkinetic\n(MK) simulation show that the effect of HER could be categorized into\ntwo groups: (1) Positive *H formation energy: HER would have no effect\non the turnover frequency (TOF) of the CO<sub>2</sub>RR. (2) Negative\n*H formation energy: HER would also have no effect to the TOF of CO<sub>2</sub>RR when the calculated limiting potential for HER is larger\nthan that for CO<sub>2</sub>RR. Otherwise, all active sites would\nbe covered by *H and poisoned before CO<sub>2</sub>RR can happen.\nThe effect of ORR could be categorized into three types: (1) ORR would\nhave no effect to the TOF of the CO<sub>2</sub>RR when ORR happened\nwith the CO<sub>2</sub>RR at the same time. (2) ORR is suppressed;\nthe active site is covered by an intermediate state (such as *OH);\nand the CO<sub>2</sub>RR is also suppressed because of the poisoned\nactive site. (3) ORR is suppressed; the active site is not covered;\nand the TOF of the CO<sub>2</sub>RR is not affected.