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Title: Structural Dynamics and Evolution of Bismuth Electrodes during Electrochemical Reduction of CO 2 in Imidazolium-Based Ionic Liquid Solutions

Abstract

Real-time changes in the composition and structure of bismuth electrodes used for catalytic conversion of CO2 into CO were examined via X-ray absorption spectroscopy (including XANES and EXAFS), electrochemical quartz crystal microbalance (EQCM), and in situ X-ray reflectivity (XR). Measurements were performed with bismuth electrodes immersed in acetonitrile (MeCN) solutions containing a 1-butyl-3-methylimidazolium ([BMIM]+) ionic liquid promoter or electrochemically inactive tetrabutylammonium supporting electrolytes (TBAPF6 and TBAOTf). Altogether, these measurements show that bismuth electrodes are originally a mixture of bismuth oxides (including Bi2O3) and metallic bismuth (Bi0) and that the reduction of oxidized bismuth species to Bi0 is fully achieved under potentials at which CO2 activation takes place. Furthermore, EQCM measurements conducted during cyclic voltammetry revealed that a bismuth-coated quartz crystal exhibits significant shifts in resistance (ΔR) prior to the onset of CO2 reduction near -1.75 V vs Ag/AgCl and pronounced hysteresis in frequency (Δf) and ΔR, which suggests significant changes in roughness or viscosity at the Bi/[BMIM]+ solution interface. In situ XR performed on rhombohedral Bi (001) oriented films indicates that extensive restructuring of the bismuth film cathodes takes place upon polarization to potentials more negative than -1.6 V vs Ag/AgCl, which is characterized by a decrease of the Bimore » (001) Bragg peak intensity of ≥50% in [BMIM]OTf solutions in the presence and absence of CO2. Over 90% of the reflectivity is recovered during the anodic half-scan, suggesting that the structural changes are mostly reversible. In contrast, such a phenomenon is not observed for thin Bi (001) oriented films in solutions of tetrabutylammonium salts that do not promote CO2 reduction. Overall, these results highlight that Bi electrodes undergo significant potential-dependent chemical and structural transformations in the presence of [BMIM]+-based electrolytes, including the reduction of bismuth oxide to bismuth metal and changes in roughness and near-surface viscosity.« less

Authors:
ORCiD logo [1];  [1];  [1];  [1]; ; ORCiD logo; ORCiD logo [2];  [2];  [2]; ORCiD logo; ORCiD logo [2]; ORCiD logo [1]
  1. Chemical Sciences and Engineering Division, Argonne National Laboratory, Lemont, Illinois 60439, United States
  2. Department of Chemistry and Biochemistry, University of Delaware, Newark, Delaware 19716, United States
Publication Date:
Research Org.:
Brookhaven National Laboratory (BNL), Upton, NY (United States)
Sponsoring Org.:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22)
OSTI Identifier:
1409611
Report Number(s):
BNL-114663-2017-JA¿¿¿
Journal ID: ISSN 2155-5435
DOE Contract Number:
SC0012704
Resource Type:
Journal Article
Resource Relation:
Journal Name: ACS Catalysis; Journal Volume: 7; Journal Issue: 10
Country of Publication:
United States
Language:
English
Subject:
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY

Citation Formats

Medina-Ramos, Jonnathan, Lee, Sang Soo, Fister, Timothy T., Hubaud, Aude A., Sacci, Robert L., Mullins, David R., DiMeglio, John L., Pupillo, Rachel C., Velardo, Stephanie M., Lutterman, Daniel A., Rosenthal, Joel, and Fenter, Paul. Structural Dynamics and Evolution of Bismuth Electrodes during Electrochemical Reduction of CO 2 in Imidazolium-Based Ionic Liquid Solutions. United States: N. p., 2017. Web. doi:10.1021/acscatal.7b01370.
Medina-Ramos, Jonnathan, Lee, Sang Soo, Fister, Timothy T., Hubaud, Aude A., Sacci, Robert L., Mullins, David R., DiMeglio, John L., Pupillo, Rachel C., Velardo, Stephanie M., Lutterman, Daniel A., Rosenthal, Joel, & Fenter, Paul. Structural Dynamics and Evolution of Bismuth Electrodes during Electrochemical Reduction of CO 2 in Imidazolium-Based Ionic Liquid Solutions. United States. doi:10.1021/acscatal.7b01370.
Medina-Ramos, Jonnathan, Lee, Sang Soo, Fister, Timothy T., Hubaud, Aude A., Sacci, Robert L., Mullins, David R., DiMeglio, John L., Pupillo, Rachel C., Velardo, Stephanie M., Lutterman, Daniel A., Rosenthal, Joel, and Fenter, Paul. Thu . "Structural Dynamics and Evolution of Bismuth Electrodes during Electrochemical Reduction of CO 2 in Imidazolium-Based Ionic Liquid Solutions". United States. doi:10.1021/acscatal.7b01370.
@article{osti_1409611,
title = {Structural Dynamics and Evolution of Bismuth Electrodes during Electrochemical Reduction of CO 2 in Imidazolium-Based Ionic Liquid Solutions},
author = {Medina-Ramos, Jonnathan and Lee, Sang Soo and Fister, Timothy T. and Hubaud, Aude A. and Sacci, Robert L. and Mullins, David R. and DiMeglio, John L. and Pupillo, Rachel C. and Velardo, Stephanie M. and Lutterman, Daniel A. and Rosenthal, Joel and Fenter, Paul},
abstractNote = {Real-time changes in the composition and structure of bismuth electrodes used for catalytic conversion of CO2 into CO were examined via X-ray absorption spectroscopy (including XANES and EXAFS), electrochemical quartz crystal microbalance (EQCM), and in situ X-ray reflectivity (XR). Measurements were performed with bismuth electrodes immersed in acetonitrile (MeCN) solutions containing a 1-butyl-3-methylimidazolium ([BMIM]+) ionic liquid promoter or electrochemically inactive tetrabutylammonium supporting electrolytes (TBAPF6 and TBAOTf). Altogether, these measurements show that bismuth electrodes are originally a mixture of bismuth oxides (including Bi2O3) and metallic bismuth (Bi0) and that the reduction of oxidized bismuth species to Bi0 is fully achieved under potentials at which CO2 activation takes place. Furthermore, EQCM measurements conducted during cyclic voltammetry revealed that a bismuth-coated quartz crystal exhibits significant shifts in resistance (ΔR) prior to the onset of CO2 reduction near -1.75 V vs Ag/AgCl and pronounced hysteresis in frequency (Δf) and ΔR, which suggests significant changes in roughness or viscosity at the Bi/[BMIM]+ solution interface. In situ XR performed on rhombohedral Bi (001) oriented films indicates that extensive restructuring of the bismuth film cathodes takes place upon polarization to potentials more negative than -1.6 V vs Ag/AgCl, which is characterized by a decrease of the Bi (001) Bragg peak intensity of ≥50% in [BMIM]OTf solutions in the presence and absence of CO2. Over 90% of the reflectivity is recovered during the anodic half-scan, suggesting that the structural changes are mostly reversible. In contrast, such a phenomenon is not observed for thin Bi (001) oriented films in solutions of tetrabutylammonium salts that do not promote CO2 reduction. Overall, these results highlight that Bi electrodes undergo significant potential-dependent chemical and structural transformations in the presence of [BMIM]+-based electrolytes, including the reduction of bismuth oxide to bismuth metal and changes in roughness and near-surface viscosity.},
doi = {10.1021/acscatal.7b01370},
journal = {ACS Catalysis},
number = 10,
volume = 7,
place = {United States},
year = {Thu Sep 14 00:00:00 EDT 2017},
month = {Thu Sep 14 00:00:00 EDT 2017}
}
  • Real-time changes in the composition and structure of bismuth electrodes used for catalytic conversion of CO 2 into CO were examined via X-ray absorption spectroscopy (including XANES and EXAFS), electrochemical quartz crystal microbalance (EQCM) and in situ X-ray reflectivity (XR). Measurements were performed with bismuth electrodes immersed in acetonitrile (MeCN) solutions containing a 1-butyl-3-methylimidazolium ([BMIM] +) ionic liquid promoter or electrochemically inactive tetrabutylammonium supporting electrolytes (TBAPF 6 or TBAOTf). Altogether, these measurements show that bismuth electrodes are originally a mixture of bismuth oxides (including Bi 2O 3) and metallic bismuth (Bi 0), and that the reduction of oxidized bismuth speciesmore » to Bi 0 is fully achieved under potentials at which CO 2 activation takes place. Furthermore, EQCM measurements conducted during cyclic voltammetry revealed that a bismuth-coated quartz crystal exhibits significant shifts in resistance (ΔR) prior to the onset of CO 2 reduction near -1.75 V vs. Ag/AgCl and pronounced hysteresis in frequency (Δf) and ΔR, which suggests significant changes in roughness or viscosity at the Bi/[BMIM] + solution interface. In situ XR performed on rhombohedral Bi (001) oriented films indicates extensive restructuring of the bismuth film cathodes takes place upon polarization to potentials more negative than -1.6 V vs. Ag/AgCl, which is characterized by a decrease of the Bi (001) Bragg peak intensity of ≥50% in [BMIM]OTf solutions in the presence and absence of CO 2. Over 90% of the reflectivity is recovered during the anodic half-scan, suggesting that the structural changes are mostly reversible. By contrast, such a phenomenon is not observed for thin Bi (001) oriented films in solutions of tetrabutylammonium salts that do not promote CO 2 reduction. In conclusion, these results highlight that Bi electrodes undergo significant potential-dependent chemical and structural transformations in the presence of [BMIM] + based electrolytes, including the reduction of bismuth oxide to bismuth metal, changes in roughness and near-surface viscosity.« less
    Cited by 1
  • Bismuth electrodes undergo distinctive electrochemically induced structural changes in nonaqueous imidazolium ([Im])(+))-based ionic liquid solutions under cathodic polarization. In situ X-ray reflectivity (XR) studies have been undertaken to probe well-ordered Bi (001) films which originally contain a native Bi 2O 3 layer. This oxide layer gets reduced to Bi(0)during the first cyclic voltammetry (CV) scan in acetonitrile solutions containing 1-butyl-3-methylimidazolium ([BMIM](+)) electrolytes. Approximately 60% of the Bi (001) Bragg peak reflectivity is lost during a potential sweep between -1.5 and -1.9 V vs Ag/AgCI due to a similar to 4-10% thinning and a similar to 40% decrease in lateral sizemore » of Bi (001) domains, which are mostly reversed during the anodic scan. Repeated potential cycling enhances the thinning and roughening of the films, suggesting that partial dissolution of Bi ensues during negative polarization. The mechanism of this behavior is understood through molecular dynamics simulations using ReaxFF and density functional theory (DFT) calculations. Both approaches indicate that [Im] + cations bind to the metal surface more strongly than tetrabutylammonium (TBA +) as the potential and the charge on the Bi surface become more negative. ReaxFF simulations predict a higher degree of disorder for a negatively charged Bi (001) slab in the presence of the [Im](+)cations and substantial migration of Bi atoms from the surface. DFT simulations show the formation of Bi center dot center dot center dot[Im] + complexes that lead to the dissolution of Bi atoms from step edges on the Bi (001) surface at potentials between -1.65 and -1.95 V. Bi desorption from a flat terrace requires a potential of approximately -2.25 V. Together, these results suggest the formation of a Bi center dot center dot center dot[Im] + complex through partial cathodic corrosion of the Bi film under conditions (potential and electrolyte composition) that favor the catalytic reduction of CO 2 .« less
  • The initial charge/discharge behavior of LiNi{sub 1{minus}y}Co{sub y}O{sub 2} (0 {le} y {le} 0.2) positive electrodes has been closely examined by neutron diffraction, X-ray diffraction, X-ray absorption, and electrochemical methods. Charge/discharge experiments and neutron diffraction refinements show that capacity loss during the initial cycling of LiNi{sub 1{minus}y}Co{sub y}O{sub 2} (0 {le} y {le} 0.2) increases linearly with the excess nickel content controlled by cobalt substitution for nickel. Charge/discharge cycling with gradually increasing depth of charge indicates that most of the initial capacity loss takes place in the early stages of the first charge. X-ray absorption near-edge spectra reveal that themore » nickel and cobalt ions in Li{sub 1{minus}x}Ni{sub 1{minus}y}Co{sub y}O{sub 2} are simultaneously oxidized and that the local structure of MO{sub 6} (M = Ni, Co) octahedra is slightly distorted upon lithium deintercalation.« less
  • Room-temperature ionic liquids (RTILs) are nonvolatile, tunable solvents. The solubilities of gases, particularly CO{sub 2}, N{sub 2}, and CH{sub 4}, have been studied in a number of RTILs. Process temperature and the chemical structures of the cation and anion have significant impacts on gas solubility and gas pair selectivity. Models based on regular solution theory and group contributions are useful to predict and explain CO{sub 2} solubility and selectivity in imidazolium-based RTILs. In addition to their role as a physical solvent, RTILs might also be used in supported ionic liquid membranes (SILMs) as a highly permeable and selective transport medium.more » Performance data for SILMs indicates that they exhibit large permeabilities as well as CO{sub 2}/N{sub 2} selectivities that outperform many polymer membranes. Furthermore, the greatest potential of RTILs for CO{sub 2} separations might lie in their ability to chemically capture CO{sub 2} when used in combination with amines. Amines can be tethered to the cation or the anion, or dissolved in RTILs, providing a wide range of chemical solvents for CO{sub 2} capture. However, despite all of their promising features, RTILs do have drawbacks to use in CO{sub 2} separations, which have been overlooked as appropriate comparisons of RTILs to common organic solvents and polymers have not been reported. A thorough summary of the capabilities-and limitations-of imidazolium-based RTILs in CO{sub 2}-based separations with respect to a variety of materials is thus provided.« less