Electrochemical CO2 reduction on hydrophobic electrode

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Electrochemical CO2 reduction
Literature Presentation Debabrata Bagchi Ph. D.
Student 26/09/2020
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Designing Catalyst for Electrochemical CO2
Reduction
High density of grain boundaries
Cu copper states
Residual surface oxygen
Cation effect
Local pH gradient
Under-coordinated sites
Halide ion
Ensemble effect

• Various approaches but no unified solution are
  proposed for CO2RR toward C2 chemicals
  production

 Chem. Rev. 2019, 119, 7610-7672.
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Here we report a fluorine-modified copper
catalyst that exhibits an ultrahigh current
density of 1.6 Acm-2 with a C2 (mainly ethylene
and ethanol) Faradaic efficiency of 80 for
electrocatalytic CO2 reduction in a flow cell. We
show a hydrogen-assisted CC coupling mechanism
between adsorbed CHO intermediates for C2
formation. Fluorine enhances water activation, CO
adsorption and hydrogenation of adsorbed CO to
CHO intermediate that can readily undergo
coupling.
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Halogen-modified copper catalysts
Solvothermal Synthesis Cu(OH)F
Cu(NO3)2. 2H2O, NH4NF2 DMF, At 160oC for 4h
NH4Cl,/NH4Br/CH4I in (ethanolwater) Stirring
Halide exchange
Cu(OH)F Cu(OH)Cl Cu(OH)Br Cu(OH)I
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Electrochemical Set-Up
1 M KOH
Current density increased with the
electronegativity of the halogen
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Electrocatalytic CO2RR performances

F-Cu
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Electrocatalytic CO2RR performances
F-Cu
F-Cu
Cl-Cu
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The normalized C2 formation rates
The normalized C2 formation rates also increased
in the sequence of Cult I-Cult Br-Cult Cl-Cult F-Cu
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Effect of Electrolyte Concentration
0.75 M KOH
1.0 M KOH
2.5 M KOH
Half-cell energy conversion efficiency
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Full-cell CO2RR performances
Ni foam_at_NiFeOx anode
37 for C2 products_at_132 mA cm-2 at 2.4 V in 2.5
M KOH
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Effect of CO2 flow rate on CO2RR over F-Cu
catalyst
Current density 1,600 mA cm-2 in 0.75 M KOH
electrolyte
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PXRD of Cu-X precursors
Cu(OH)F
Cu2(OH)3Cl
Cu2(OH)3Cl
CuI
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PXRD of Cu-X
GDL
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Electron microscopy study of Cu-X
after CO2RR
after CO2RR
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XPS of Xs in Cu-X
surface halogen contents measured by XPS for the
X-Cu catalysts were 6 mol, which is higher than
their bulk contents (2 mol), BY EDX
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XPS and XAS study of X-Cu
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Density functional theory calculations
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Functioning mechanism of fluorine
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In situ ATR-FTIR Spectroscopy
FCu catalyst
Cu catalyst

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Mechanistic Investigation
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Preparation of the carbon-supported Cu SA
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Characterisation of Cu SA
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Electrocatalytic CO2RR performances
Cu/C-0.4
-0.6 V.
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Mechanistic investigation by Operando XAS
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