Electrochemical CO2 Reduction in acidic media

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Electrochemical CO2 reduction in Acid medium
Literature Presentation Debabrata Bagchi Ph. D.
Student 11/09/2021
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1-3University of Toronto, Canada 2University
of Sydney.
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CO2RR in basic, acid neutral media
Acidic electrolyte
(CEM, nafion)
Neutral/alkaline electrolyte
(AEM, fumasep)
CO2RR in flow cell
Adv. Funct. Mater. 2021, 2102151
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CO2RR in Flow cell and MEA
Alkaline Flow Cell
Neutral Flow Cell
MEA Electrolyzer
Joule 2019, 3, 27772791
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Alkaline vs. Acidic Electrolyte
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Which is good electrolyte
Goal
High Current High CO2RR yield Low carbonate
formation
Low CO2RR yield as high HER
High Current
No carbonate formation
Acid
(H)
High Current
Neutral
Alkaline
Low Current
Moderate CO2RR yield
High CO2RR yield
(CO3-)
(OH-)
Low carbonate formation
High carbonate formation
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Acidic Electrolyte
Acid with CEM _at_400 mA/cm2
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CO2 crossover tests in different electrolytes
1 M KHCO3 with AEM
0.5 M H3PO4 0.5 M KH2PO4 with CEM
Acid with CEM
Acid with CEM
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Central concept
Cation augmenting strategy to improve CO2
activation kinetics in strong acid
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Modelling of pH near the cathode
pH 1.94
pH 3.02
pH 3.96
pH 2
pH 3
pH 4
H3O mass transport limitation occurs and H2O
becomes the main proton donor at the cathode
surface
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Effect of KCl addition
200 mA/cm2
Faradaic efficiency on sputtered Ag with
different KCl concentrations
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Effect of K addition
(A) 1 M H3PO4. (B) 1 M H3PO4 1 M KCl. (C) 1 M
H3PO4 2 M KCl. (D) 1 M H3PO4 3 M KCl
K does not play a role in theactivation of CO2
nor does it suppress HERin a locally acidic
environment
At current densities lt200 mA/cm2
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Cation-enabled CO2 reduction in acid
1 M H3PO4 and 3 M KCl
1M H3PO4 at 400 mA/cm2
1 M H3PO4 and 3 M KCl on Cu
Tafel slope analysis
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Role of K on HER and CO2RR
1 M KCl
3 M KCl
Under a proton-depletion local environment, the
cation triggers CO2 activation,
Total 400 mA/cm2
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Control study Effect of anions on CO2RR
In-situ EXAFS
_at_ 400 mA/cm2
K is not changing electronic state of Cu
Overall activity
?
How to get more K near electrode surface
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Use of Cation-augmenting layer (CAL)
perfluorosulfonic acid
v
FE at different J
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XPS of CAL
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CuNPs/PFSA composite material
1 M KCl
2 M KCl
3 M KCl
CO2R selectivity reached61, including a total
C2FE of 40
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Extended CO2R performance
1 M H3PO4 3 M KCl
Current density of 1.2 A cm-2
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Operational cost breakdown of neutral CO2RR MEA
electrolyzer and alkaline flow-cell electrolyzer
in ideal scenario
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Techno-economic assessment of neutral CO2R MEA
electrolyzer and alkaline flowcell electrolyzer,
together with specific cost distribution per ton
of ethylene produced
Acid
High Current
High CO2RR yield
No carbonate formation
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