Journal
PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA
Volume 116, Issue 16, Pages 7718-7722Publisher
NATL ACAD SCIENCES
DOI: 10.1073/pnas.1821709116
Keywords
quantum mechanics; molecular dynamics; vibration mode; CO2 reduction reaction; reaction mechanism
Categories
Funding
- Joint Center for Artificial Photosynthesis, a Department of Energy (DOE) Energy Innovation Hub
- Office of Science of the US DOE [DE-SC0004993]
- National Science Foundation [ACI-1053575]
- Collaborative Innovation Center of Suzhou Nano Science Technology
- Priority Academic Program Development of Jiangsu Higher Education Institutions (PAPD)
- 111 Project
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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 CO2 (b-CO2),*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-0 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.
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