Click to edit Master title style Natalia Garcia Rey and Dana D. Dlott University of Illinois at...
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Click to edit Master title style Click to edit Master title style Natalia Garcia Rey and Dana D. Dlott University of Illinois at Urbana-Champaign International Symposium on Molecular Spectroscopy 70 th Meeting, Champaign-Urbana Vibrational Sum Frequency Spectroscopy study of the CO 2 electroreduction mediated by ionic liquid-water on Ag
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CO 2 electroreduction at low-overpotential o Ionic liquid mediated the CO 2 electroreduction into CO at low-overpotential 1,2. o Water increases Faradaic efficiency. H2H2 CO 2 Ionic liquid: EMIM-BF 4 Ag CO H2OH2O (1) Rosen, B. A. et al., Science 2011, 334, 643; (2) Rosen, B. A. et al., J. Electroch. So. 2013, 160, H138.
Transcript of Click to edit Master title style Natalia Garcia Rey and Dana D. Dlott University of Illinois at...
Click to edit Master title style
Click to edit Master title style
Natalia Garcia Rey and Dana D. DlottUniversity of Illinois at Urbana-Champaign
International Symposium on Molecular Spectroscopy70th Meeting, Champaign-Urbana
Vibrational Sum Frequency Spectroscopy study of the CO2 electroreduction mediated by ionic liquid-water on Ag
Electrolyzer
Energy
CO2 Filter
Air
H2
Filtered Air
Fuel
Water electrolys
er
Synthesis
Energy
Efficient CO2 electroreduction: Recycling CO2 Production of hydrocarbon
fuels
CO2 CO
Artificial Photosynthesis
CO2 electroreduction at low-overpotential
o Ionic liquid mediated the CO2 electroreduction into CO at low-overpotential1,2.
o Water increases Faradaic efficiency.
H2
CO2Ionic liquid:EMIM-BF4
Ag
CO
H2O
(1) Rosen, B. A. et al., Science 2011, 334, 643; (2) Rosen, B. A. et al., J. Electroch. So. 2013, 160, H138.
Vibrational sum frequency spectroscopy synchronized with cell
potential allowed us to…o CO produced in the cell from the CO2.
CO adsorbs on Ag but not poisons the electrode CO stretching mode at IR 2100 cm-1.
o The ionic liquid-water-Ag interface controls the CO2 electroreduction nonresonant sum frequency at IR 2600 cm-1.
o Water concentration shifts the structural orientation to lower potentials nonresonant sum frequency at IR 2600 cm-1.
polarizationanalyzer
lens
Ti:sapphireLaser
120 fs 800 nm
1.8 mJ @ 3 kHz
Rep. rate
opticalparametric amplifier(OPA)
2.5–16 µm4µJ @ 5µm
delay stage
60°
Fabry-Perotétalon
short-pass filter (738 nm)
Ge filter
grating
slit
potentiostat
counterelectrode
electrode referenceelectrode
spectro-graph
BBIR
NBvis
VSFS
CCD
CCDcomputer
potentiostatcomputer
trigger
PtCO2
Luggin cappilary
Ag/AgCl
VSFS-CV setup
-2.0 -1.5 -1.0 -0.5
-0.2
-0.1
0.0
curr
ent (
mA
)potential vs. Ag/AgCl (V)
onset of CO2
reduction
Ag working electrodenegative potential
CaF2 window
O C O
BF4-
+ +
O C O
O C O
O C
O
O C O
O C O
O C
O
O C O
O C O
+
BF4- BF4
-
BF4-
EMIM+ BF4-
O C
O
O C O
O C
O
O C
O
O C
O
O C OO C O
O C O
innerregion
diffuseregion
doublelayer
25 mmelectrolyte
+
++
+
+
BF4-
BF4-
BF4-
BF4-
+BF4
-
BF4-
O C O
O C O
O C OO
C O
OHH
O HH
OHH
OH
H
OH
H
OH H
OH
H
OH
H
OH
H
OHH
OHH
OH H +
BF4-
+
CO2 electroreduction in situ on cathode
mediated by room temperature ionic liquid (RTIL) EMIM-BF4
-2.0 -1.5 -1.0 -0.5
-0.2
-0.1
0.0
curr
ent (
mA
)potential vs. Ag/AgCl (V)
onset of CO2
reduction
Ag working electrodenegative potential
CaF2 window
O C O
BF4-
+ +
O C O
O C O
O C
O
O C O
O C O
O C
O
O C O
O C O
+
BF4- BF4
-
BF4-
EMIM+ BF4-
O C
O
O C O
O C
O
O C
O
O C
O
O C OO C O
O C O
innerregion
diffuseregion
doublelayer
25 mmelectrolyte
+
++
+
+
BF4-
BF4-
BF4-
BF4-
+BF4
-
BF4-
O C O
O C O
O C OO
C O
OHH
O HH
OHH
OH
H
OH
H
OH H
OH
H
OH
H
OH
H
OHH
OHH
OH H +
BF4-
+
CO2 electroreduction in situ on cathode
mediated by room temperature ionic liquid (RTIL) EMIM-BF4
OC
OC
OC
OC
OC
OC
OC
OC
OC
OC
OC
OC
Ar
CO2
Resonant VSFS vs Cell PotentialCO2 electroreduction in EMIM-BF4 / 0.3% H20 /
Ag
-1.5 -1.0 -0.5
2080
2090
2100
2110
wav
enum
ber (
cm-1)
potential vs. Ag/AgCl (V)
CO stretching mode
22 cm-1/V
*mol% of water
Resonant VSFS vs Cell PotentialCO2 electroreduction in EMIM-BF4 / 0.3% H20 /
Ag
-1.5 -1.0 -0.5
2080
2090
2100
2110
wav
enum
ber (
cm-1)
potential vs. Ag/AgCl (V)
CO stretching mode
22 cm-1/V
*mol% of water
Non
reso
nant
SF
Inte
nsity
30002000
IR frequency / cm-1
-0.5
-1.8
-0.5
Nonresonant VSFS vs Cell PotentialCO2 electroreduction EMIM-BF4 / 0.3%
H20 / Ag
Pote
ntial
vs A
g/Ag
Cl
/ V
IR
VIS VSFS
Nonresonant SF vs cell potential:CO2 electroreduction in EMIM-BF4 / 0.3%
H20 / Ag
-2-10
pote
ntia
l (V
)
0 200 400 600 800 1000 1200 1400 1600 18000
2
4
Non
reso
nant
SF
Inte
nsity
time (s)
-0.2
-0.1
0.0
CO2
Arcurr
ent
(mA
)
Nonresonant SF vs cell potential:CO2 electroreduction in EMIM-BF4 / 0.3%
H20 / Ag
0
2
4
Non
reso
nant
SF
Inte
nsity
-0.5 to -2 V Ar CO2
Ar- and CO2 saturated EMIM-BF4 on Ag
-0.5 -1.0 -1.5
-0.2
-0.1
0.0
Cur
rent
(mA
)
Potential vs Ag/AgCl (V)
Addition of water
-1.5 -1.0 -0.50.0
0.5
1.0
Non
reso
nant
SF
Inte
nsity
0.3% 16% 27% 45% 64% 80%
130 mVNeat EMIM-BF4 adding mol % by mol of water
cell potential (V)
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Take home message
o CO2 electroreduction into CO was observed. A minimum in the nonresonant SF was found at the same potential, -1.33V.
o CO was the specie mainly produced, not poisoning the Ag electrode
o The structural transition of the water-EMIM-BF4 on Ag, the double layer, mediated the CO2 electroreduction.
o Increase in water concentration shifts the EMIM-BF4 on Ag structural transition to a lower cell potentials.
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Acknowledgments
Prof. Dana D. DlottDlott’s group
Thank you all for your attention!
Any questions?
