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Title: Quantum chemical studies of redox properties and conformational changes of a four-center iron CO 2 reduction electrocatalyst

The CO 2 reduction electrocatalyst [Fe 4N(CO) 12] - (abbrev. 1 -) reduces CO 2 to HCO 2 - in a two-electron, one-proton catalytic cycle. Here, we employ ab initio calculations to estimate the first two redox potentials of 1 - and explore the pathway of a side reaction involving CO dissociation from 1 3-. Using the BP86 density functional approximation, the redox potentials were computed with a root mean squared error of 0.15 V with respect to experimental data. High temperature Born–Oppenheimer molecular dynamics was employed to discover a reaction pathway of CO dissociation from 1 3- with a reaction energy of +10.6 kcal mol -1 and an activation energy of 18.8 kcal mol -1; including harmonic free energy terms, this yields ΔG sep = 1.4 kcal mol -1 for fully separated species and ΔG = +17.4 kcal mol -1, indicating CO dissociation is energetically accessible at ambient conditions. The analogous dissociation pathway from 1 2- has a reaction energy of 22.1 kcal mol -1 and an activation energy of 22.4 kcal mol -1 (ΔG sep = 12.8 kcal mol -1, ΔG = +18.1 kcal mol -1). Our computed harmonic vibrational analysis of [Fe 4N(CO) 11] 3-more » or 2 3- reveals a distinct CO-stretching peak red-shifted from the main CO-stretching band, pointing to a possible vibrational signature of dissociation. Multi-reference CASSCF calculations are used to check the assumptions of the density functional approximations that were used to obtain the majority of the results.« less
Authors:
ORCiD logo [1] ; ORCiD logo [1] ;  [1] ;  [1] ; ORCiD logo [1] ; ORCiD logo [1]
  1. Univ. of California, Davis, CA (United States). Dept. of Chemistry
Publication Date:
Grant/Contract Number:
SC0016395; 58158-DNI6
Type:
Published Article
Journal Name:
Chemical Science
Additional Journal Information:
Journal Volume: 9; Journal Issue: 10; Journal ID: ISSN 2041-6520
Publisher:
Royal Society of Chemistry
Research Org:
Univ. of California, Davis, CA (United States)
Sponsoring Org:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22); ACS Petroleum Research Fund (United States)
Country of Publication:
United States
Language:
English
Subject:
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
OSTI Identifier:
1419814
Alternate Identifier(s):
OSTI ID: 1505086

Jang, Hyesu, Qiu, Yudong, Hutchings, Marshall E., Nguyen, Minh, Berben, Louise A., and Wang, Lee-Ping. Quantum chemical studies of redox properties and conformational changes of a four-center iron CO2 reduction electrocatalyst. United States: N. p., Web. doi:10.1039/c7sc04342b.
Jang, Hyesu, Qiu, Yudong, Hutchings, Marshall E., Nguyen, Minh, Berben, Louise A., & Wang, Lee-Ping. Quantum chemical studies of redox properties and conformational changes of a four-center iron CO2 reduction electrocatalyst. United States. doi:10.1039/c7sc04342b.
Jang, Hyesu, Qiu, Yudong, Hutchings, Marshall E., Nguyen, Minh, Berben, Louise A., and Wang, Lee-Ping. 2018. "Quantum chemical studies of redox properties and conformational changes of a four-center iron CO2 reduction electrocatalyst". United States. doi:10.1039/c7sc04342b.
@article{osti_1419814,
title = {Quantum chemical studies of redox properties and conformational changes of a four-center iron CO2 reduction electrocatalyst},
author = {Jang, Hyesu and Qiu, Yudong and Hutchings, Marshall E. and Nguyen, Minh and Berben, Louise A. and Wang, Lee-Ping},
abstractNote = {The CO2 reduction electrocatalyst [Fe4N(CO)12]- (abbrev. 1-) reduces CO2 to HCO2- in a two-electron, one-proton catalytic cycle. Here, we employ ab initio calculations to estimate the first two redox potentials of 1- and explore the pathway of a side reaction involving CO dissociation from 13-. Using the BP86 density functional approximation, the redox potentials were computed with a root mean squared error of 0.15 V with respect to experimental data. High temperature Born–Oppenheimer molecular dynamics was employed to discover a reaction pathway of CO dissociation from 13- with a reaction energy of +10.6 kcal mol-1 and an activation energy of 18.8 kcal mol-1; including harmonic free energy terms, this yields ΔGsep = 1.4 kcal mol-1 for fully separated species and ΔG‡ = +17.4 kcal mol-1, indicating CO dissociation is energetically accessible at ambient conditions. The analogous dissociation pathway from 12- has a reaction energy of 22.1 kcal mol-1 and an activation energy of 22.4 kcal mol-1 (ΔGsep = 12.8 kcal mol-1, ΔG‡ = +18.1 kcal mol-1). Our computed harmonic vibrational analysis of [Fe4N(CO)11]3- or 23- reveals a distinct CO-stretching peak red-shifted from the main CO-stretching band, pointing to a possible vibrational signature of dissociation. Multi-reference CASSCF calculations are used to check the assumptions of the density functional approximations that were used to obtain the majority of the results.},
doi = {10.1039/c7sc04342b},
journal = {Chemical Science},
number = 10,
volume = 9,
place = {United States},
year = {2018},
month = {1}
}

Works referenced in this record:

Ab initio effective core potentials for molecular calculations. Potentials for K to Au including the outermost core orbitals
journal, January 1985
  • Hay, P. Jeffrey; Wadt, Willard R.
  • The Journal of Chemical Physics, Vol. 82, Issue 1, p. 299-310
  • DOI: 10.1063/1.448975

Balanced basis sets of split valence, triple zeta valence and quadruple zeta valence quality for H to Rn: Design and assessment of accuracy
journal, January 2005
  • Weigend, Florian; Ahlrichs, Reinhart
  • Physical Chemistry Chemical Physics, Vol. 7, Issue 18, p. 3297-3305
  • DOI: 10.1039/b508541a

Density?functional thermochemistry. III. The role of exact exchange
journal, April 1993
  • Becke, Axel D.
  • The Journal of Chemical Physics, Vol. 98, Issue 7, p. 5648-5652
  • DOI: 10.1063/1.464913

Molecular Catalysis of Electrochemical Reactions. Mechanistic Aspects
journal, July 2008
  • Sav�ant, Jean-Michel
  • Chemical Reviews, Vol. 108, Issue 7, p. 2348-2378
  • DOI: 10.1021/cr068079z

A new local density functional for main-group thermochemistry, transition metal bonding, thermochemical kinetics, and noncovalent interactions
journal, November 2006
  • Zhao, Yan; Truhlar, Donald G.
  • The Journal of Chemical Physics, Vol. 125, Issue 19, Article No. 194101
  • DOI: 10.1063/1.2370993

Self�Consistent Molecular Orbital Methods. XII. Further Extensions of Gaussian�Type Basis Sets for Use in Molecular Orbital Studies of Organic Molecules
journal, March 1972
  • Hehre, W. J.; Ditchfield, R.; Pople, J. A.
  • The Journal of Chemical Physics, Vol. 56, Issue 5, p. 2257-2261
  • DOI: 10.1063/1.1677527