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Detection of CO2•–in the Electrochemical Reduction of Carbon Dioxide in N,N-Dimethylformamide by Scanning Electrochemical Microscopy

Authors :
Kai, Tianhan
Zhou, Min
Duan, Zhiyao
Henkelman, Graeme A.
Bard, Allen J.
Source :
Journal of the American Chemical Society; 20240101, Issue: Preprints
Publication Year :
2024

Abstract

The electrocatalytic reduction of CO2has been studied extensively and produces a number of products. The initial reaction in the CO2reduction is often taken to be the 1e formation of the radical anion, CO2•–. However, the electrochemical detection and characterization of CO2•–is challenging because of the short lifetime of CO2•–, which can dimerize and react with proton donors and even mild oxidants. Here, we report the generation and quantitative determination of CO2•–in N,N-dimethylformamide (DMF) with the tip generation/substrate collection (TG/SC) mode of scanning electrochemical microscopy (SECM). CO2was reduced at a hemisphere-shaped Hg/Pt ultramicroelectrode (UME) or a Hg/Au film UME, which were utilized as the SECM tips. The CO2•–produced can either dimerize to form oxalate within the nanogap between SECM tip and substrate or collected at SECM substrate (e.g., an Au UME). The collection efficiency (CE) for CO2•–depends on the distance (d) between the tip and substrate. The dimerization rate (6.0 × 108M–1s–1) and half-life (10 ns) of CO2•–can be evaluated by fitting the collection efficiency vs distance curve. The dimerized species of CO2•–, oxalate, can also be determined quantitatively. Furthermore, the formal potential (E0′) and heterogeneous rate constant (k0) for CO2reduction were determined with different quaternary ammonium electrolytes. The significant difference in k0is due to a tunneling effect caused by the adsorption of the electrolytes on the electrode surface at negative potentials.

Details

Language :
English
ISSN :
00027863 and 15205126
Issue :
Preprints
Database :
Supplemental Index
Journal :
Journal of the American Chemical Society
Publication Type :
Periodical
Accession number :
ejs44219662
Full Text :
https://doi.org/10.1021/jacs.7b08702