Why heterogeneous single-atom catalysts preferentially produce CO in the electrochemical CO2 reduction reaction

Abstract

Formate and CO are competing products in the two-electron CO2 reduction reaction (2e CO2RR), and they are produced via *OCHO and *COOH intermediates, respectively. However, the factors governing CO/formate selectivity remain elusive, especially for metal–carbon–nitrogen (M–N–C) single-atom catalysts (SACs), most of which produce CO as their main product. Herein, we show computationally that the selectivity of M–N–C SACs is intrinsically associated with the CO2 adsorption mode by using bismuth (Bi) nanosheets and the Bi–N–C SAC as model catalysts. According to our results, the Bi–N–C SAC exhibits a strong thermodynamic preference toward *OCHO, but under working potentials, CO2 is preferentially chemisorbed first due to a charge accumulation effect, and subsequent protonation of chemisorbed CO2 to *COOH is kinetically much more favorable than formation of *OCHO. Consequently, the Bi–N–C SAC preferentially produces CO rather than formate. In contrast, the physisorption preference of CO2 on Bi nanosheets contributes to high formate selectivity. Remarkably, this CO2 adsorption-based mechanism also applies to other typical M–N–C SACs. This work not only resolves a long-standing puzzle in M–N–C SACs, but also presents simple, solid criteria (i.e., CO2 adsorption modes) for indicating CO/formate selectivity, which help strategic development of high-performance CO2RR catalysts.

Graphical abstract: Why heterogeneous single-atom catalysts preferentially produce CO in the electrochemical CO2 reduction reaction

Supplementary files

Article information

Article type
Edge Article
Submitted
19 Mar 2022
Accepted
03 May 2022
First published
04 May 2022
This article is Open Access

All publication charges for this article have been paid for by the Royal Society of Chemistry
Creative Commons BY-NC license

Chem. Sci., 2022, Advance Article

Why heterogeneous single-atom catalysts preferentially produce CO in the electrochemical CO2 reduction reaction

Y. Wang, T. Liu and Y. Li, Chem. Sci., 2022, Advance Article , DOI: 10.1039/D2SC01593E

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