Do the Hydrogen Evolution Reaction and Oxygen Reduction Reaction Really Need To Be Suppressed in O-Tolerant CO 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; BPy, 2,2'-bipyridine-5,5'-dicarbaldehyde; and CoPor, two-dimensional cobalt porphyrin-based covalent organic framework] and Co-TAPP [10,15,20-tetrakis(4-aminophenyl)porphinatocobalt] as two model catalysts to investigate the effect of the hydrogen evolution reaction (HER) and oxygen reduction reaction (ORR) in the O-tolerant CO electroreduction reaction (CORR). Both catalysts have been proven to have CORR activity at a potential range from -0.60 to -1.10 V when CO and O are co-feeding (Zhu, H.-J.; Si, D.-H.; Guo, H.; Chen, Z.; Cao, R.; Huang, Y.-B. Oxygen-tolerant CO electroreduction over covalent organic frameworks via photoswitching control oxygen passivation strategy. 2024, 15, 1479, DOI: 10.1038/s41467-024-45959-9). The calculated results by grand canonical density functional theory (GC-DFT) and microkinetic (MK) simulation show that the effect of HER could be categorized into two groups: (1) Positive *H formation energy: HER would have no effect on the turnover frequency (TOF) of the CORR. (2) Negative *H formation energy: HER would also have no effect to the TOF of CORR when the calculated limiting potential for HER is larger than that for CORR. Otherwise, all active sites would be covered by *H and poisoned before CORR can happen. The effect of ORR could be categorized into three types: (1) ORR would have no effect to the TOF of the CORR when ORR happened with the CORR at the same time. (2) ORR is suppressed; the active site is covered by an intermediate state (such as *OH); and the CORR is also suppressed because of the poisoned active site. (3) ORR is suppressed; the active site is not covered; and the TOF of the CORR is not affected.