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

Cheng, Tao and Fortunelli, Alessandro and Goddard, William A., III (2019) Reaction intermediates during operando electrocatalysis identified from full solvent quantum mechanics molecular dynamics. Proceedings of the National Academy of Sciences of the United States of America, 116 (16). pp. 7718-7722. ISSN 0027-8424. PMCID PMC6475413. doi:10.1073/pnas.1821709116.

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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 (CO_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 CO_2 (b-CO_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.

Item Type:Article
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URLURL TypeDescription Information CentralArticle
Cheng, Tao0000-0003-4830-177X
Fortunelli, Alessandro0000-0001-5337-4450
Goddard, William A., III0000-0003-0097-5716
Additional Information:© 2019 National Academy of Sciences. Published under the PNAS license. Contributed by William A. Goddard III, January 28, 2019 (sent for review December 20, 2018; reviewed by Sharon Hammes-Schiffer, Philippe Sautet, and Richard J. Saykally). PNAS published ahead of print March 13, 2019. This work was supported by the Joint Center for Artificial Photosynthesis, a Department of Energy (DOE) Energy Innovation Hub, supported through the Office of Science of the US DOE under Award DE-SC0004993. These studies used the Extreme Science and Engineering Discovery Environment which is supported by National Science Foundation Grant ACI-1053575. This work is supported by Collaborative Innovation Center of Suzhou Nano Science & Technology, the Priority Academic Program Development of Jiangsu Higher Education Institutions (PAPD), the 111 Project. Author contributions: T.C. and W.A.G. designed research; T.C. and A.F. performed research; T.C. and W.A.G. analyzed data; and T.C., A.F., and W.A.G. wrote the paper. Reviewers: S.H.-S., Yale University; P.S., University of California, Los Angeles; and R.J.S., University of California, Berkeley. The authors declare no conflict of interest. This article contains supporting information online at
Funding AgencyGrant Number
Joint Center for Artificial Photosynthesis (JCAP)UNSPECIFIED
Department of Energy (DOE)DE-SC0004993
Suzhou Nano Science and TechnologyUNSPECIFIED
Jiangsu Higher Education InstitutionsUNSPECIFIED
111 Project of ChinaUNSPECIFIED
Subject Keywords:quantum mechanics; molecular dynamics; vibration mode; CO_2 reduction reaction; reaction mechanism
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Issue or Number:16
PubMed Central ID:PMC6475413
Record Number:CaltechAUTHORS:20190313-133027865
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Official Citation:Reaction intermediates during operando electrocatalysis identified from full solvent quantum mechanics molecular dynamics. Tao Cheng, Alessandro Fortunelli, William A. Goddard. Proceedings of the National Academy of Sciences Apr 2019, 116 (16) 7718-7722; DOI: 10.1073/pnas.1821709116
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:93786
Deposited By: Tony Diaz
Deposited On:13 Mar 2019 21:05
Last Modified:01 Mar 2022 18:03

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