Direct Methanol Fuel Cell

1
Direct Methanol Fuel Cell Study on anode and
cathode catalysts
???
2
Introduction

• Direct methanol fuel cells
• Major problems facing DMFCs

Study on the anode electrocatalyst(Pt-Ruad)
Study on the cathode electrocatalyst(Ru/Se)
Acknowledgements
3
Direct Methanol Fuel Cell
e-
Load

-
O2 (air)
e-
CH3OH H2O
H
e-
O2
CO2
H2O
H2O CH3OH
PEM
Anode
Cathode
Membrane Electrode Assembly (MEA)
E -0.02V
E 1.23V
E 1.21V
4

• Power vehicles
• More efficient than ICE
• (97 vs. 40).
• Lower emission(no NOx).
• Quite.

• Power portable
• electronic devices
• Last longer than batteries.
• Easy to refill.

5
Key Issues Hindering the Development of
Practical DMFCs
Ecel l E?cell - ( ??a? ??c? ) Ecell /
E?cell ltlt 100
?--???

• Develop active methanol electrooxidation
  catalysts.
• Overcome methanol crossover issue.

6
What I have done on the study of
anode (University of Alberta, Canada)
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Best catalyst for CH3OH electrooxidation PtRu
nanoparticles

• What is the optimum surface composition?
• Best PtRu ratio?
• ? Hard to measure surf. comp.
• of nanoparticle PtRu.
• ? 1050 Ru was reported.

8
H
K2S2O8 in 4.0 M KOH
of surf. Pt atom was measured by cyclic
voltammetry(CV)
Inductively Coupled Plasma- Atomic Emission
Spectrometry (ICP-AES)
of Ru atom
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of Deposition (n) 1 2 3 5 7
Surf. Equiv. Ruad 0.18 0.38 0.57 0.85 1.31
(Surf. Equiv. Ruad)/n 0.18 0.19 0.19 0.17 0.19
Ru Surf. Coverage 0.18 0.33 0.45 0.63 0.75
1) Ruad form a submonolayer on the substrate at
each deposition. 2) Ruad were deposited onto
Ptsurf and Ruad at similar probabilities.
Cao, D. X. Bergens, S. H. Electrochimica Acta,
2003, 48, 4021-4031.
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?Ru 0.33 0.45 0.18 0.63 0.75 Pt
1 M CH3OH 1 M H2SO4
?Ru 0.33 0.45 0.63 0.75 0.18 Pt
PtRu 6733
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Membrane Electrode Assembly (MEA)
Anode Pt-Ruad
Cathode Pt black
Nanoparticle catalysts
Nafion? ionomer
Nafion?-117
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Nafion?-117 Membrane
CF22
CF22
CF22
CF22
SO3-
SO3-
SO3-
SO3-
H2O
H
H
H2O
CH3OH
H
H2O
H
CH3OH
H2O
H2O
H2O
H2O
H
H2O
CH3OH
H
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Hot-Pressing (125oC, 1500psig)
Ink Preparation (sonication)
Painting
Steel plate
Paint brush
Catalyst layer
Nafion-117 membrane
Teflon tape
Teflon decal
Catalyst / Water / Nafion
Fuel Cell Hardware
Membrane Electrode Assembly
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(No Transcript)
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CVs for fresh Pt-Ruad
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CVs measured in fuel cells
H2O (Ar)
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Is Pt-Ruad stable? (Ruad might come off)
Fuel Cell Stability Test
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What I have done on the study of
cathode (University of Illinois, USA)
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Problems
Methanol crossover causes a mixed potential at
cathode, increases the cathode overpotential,
decreases fuel cell voltage, thereby efficiency.
Solutions

• Methanol impermeable
• membrane.
• Methanol tolerant ORR
• electrocatalysts.

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Oxygen Reduction Reaction
Activity Comparison
Ru/Se
????
Methanol Tolerance
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Acknowledgements

• People

Dr. Steve Bergens
Dr. Andrzej Wieckowski

• Funding

Natural Sciences and Engineering Research Council
of Canada.
US Army Research Office (MURI grant
DAAD19-03-1-0169) .