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Title: Reaction intermediates during operando electrocatalysis identified from full solvent quantum mechanics molecular dynamics

Abstract

Electrocatalysis provides a powerful means to selectively transform molecules, but a serious impediment in making rapid progress is the lack of a molecular-based understanding of the reactive mechanisms or intermediates at the electrode–electrolyte interface (EEI). Recent experimental techniques have been developed for operando identification of reaction intermediates using surface infrared (IR) and Raman spectroscopy. However, large noises in the experimental spectrum pose great challenges in resolving the atomistic structures of reactive intermediates. To provide an interpretation of these experimental studies and target for additional studies, we report the results from quantum mechanics molecular dynamics (QM-MD) with explicit consideration of solvent, electrode–electrolyte interface, and applied potential at 298 K, which conceptually resemble the operando experimental condition, leading to a prototype of operando QM-MD (o-QM-MD). With o-QM-MD, we characterize 22 possible reactive intermediates in carbon dioxide reduction reactions ( C O 2 RRs). Furthermore, we report the vibrational density of states (v-DoSs) of these intermediates from two-phase thermodynamic (2PT) analysis. Accordingly, we identify important intermediates such as chemisorbed C O 2 ( b - C O 2 ), *HOC-COH, *C-CH, and *C-COH in our o-QM-MD likely to explain the experimental spectrum. Indeed, we assign the experimental peak at 1,191 cm −1 to the mode of C-O stretch in *HOC-COH predicted at 1,189 cm −1 and the experimental peak at 1,584 cm −1 to the mode of C-C stretch in *C-COD predicted at 1,581 cm −1 . Interestingly, we find that surface ketene (*C=C=O), arising from *HOC-COH dehydration, also shows signals at around 1,584 cm −1 , which indicates a nonelectrochemical pathway of hydrocarbon formation at low overpotential and high pH conditions.

Authors:
ORCiD logo; ; ORCiD logo
Publication Date:
Sponsoring Org.:
USDOE Office of Electricity Delivery and Energy Reliability (OE), Power Systems Engineering Research and Development (R&D) (OE-10)
OSTI Identifier:
1499812
Grant/Contract Number:  
SC0004993
Resource Type:
Journal Article: Published Article
Journal Name:
Proceedings of the National Academy of Sciences of the United States of America
Additional Journal Information:
Journal Name: Proceedings of the National Academy of Sciences of the United States of America Journal Volume: 116 Journal Issue: 16; Journal ID: ISSN 0027-8424
Publisher:
Proceedings of the National Academy of Sciences
Country of Publication:
United States
Language:
English

Citation Formats

Cheng, Tao, Fortunelli, Alessandro, and Goddard, III, William A. Reaction intermediates during operando electrocatalysis identified from full solvent quantum mechanics molecular dynamics. United States: N. p., 2019. Web. doi:10.1073/pnas.1821709116.
Cheng, Tao, Fortunelli, Alessandro, & Goddard, III, William A. Reaction intermediates during operando electrocatalysis identified from full solvent quantum mechanics molecular dynamics. United States. doi:10.1073/pnas.1821709116.
Cheng, Tao, Fortunelli, Alessandro, and Goddard, III, William A. Wed . "Reaction intermediates during operando electrocatalysis identified from full solvent quantum mechanics molecular dynamics". United States. doi:10.1073/pnas.1821709116.
@article{osti_1499812,
title = {Reaction intermediates during operando electrocatalysis identified from full solvent quantum mechanics molecular dynamics},
author = {Cheng, Tao and Fortunelli, Alessandro and Goddard, III, William A.},
abstractNote = {Electrocatalysis provides a powerful means to selectively transform molecules, but a serious impediment in making rapid progress is the lack of a molecular-based understanding of the reactive mechanisms or intermediates at the electrode–electrolyte interface (EEI). Recent experimental techniques have been developed for operando identification of reaction intermediates using surface infrared (IR) and Raman spectroscopy. However, large noises in the experimental spectrum pose great challenges in resolving the atomistic structures of reactive intermediates. To provide an interpretation of these experimental studies and target for additional studies, we report the results from quantum mechanics molecular dynamics (QM-MD) with explicit consideration of solvent, electrode–electrolyte interface, and applied potential at 298 K, which conceptually resemble the operando experimental condition, leading to a prototype of operando QM-MD (o-QM-MD). With o-QM-MD, we characterize 22 possible reactive intermediates in carbon dioxide reduction reactions ( C O 2 RRs). Furthermore, we report the vibrational density of states (v-DoSs) of these intermediates from two-phase thermodynamic (2PT) analysis. Accordingly, we identify important intermediates such as chemisorbed C O 2 ( b - C O 2 ), *HOC-COH, *C-CH, and *C-COH in our o-QM-MD likely to explain the experimental spectrum. Indeed, we assign the experimental peak at 1,191 cm −1 to the mode of C-O stretch in *HOC-COH predicted at 1,189 cm −1 and the experimental peak at 1,584 cm −1 to the mode of C-C stretch in *C-COD predicted at 1,581 cm −1 . Interestingly, we find that surface ketene (*C=C=O), arising from *HOC-COH dehydration, also shows signals at around 1,584 cm −1 , which indicates a nonelectrochemical pathway of hydrocarbon formation at low overpotential and high pH conditions.},
doi = {10.1073/pnas.1821709116},
journal = {Proceedings of the National Academy of Sciences of the United States of America},
issn = {0027-8424},
number = 16,
volume = 116,
place = {United States},
year = {2019},
month = {3}
}

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Works referenced in this record:

A review of the aqueous electrochemical reduction of CO2 to hydrocarbons at copper
journal, August 2006


Electrochemical CO2 Reduction on Metal Electrodes
book, January 2008