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Direct Methanol Fuel Cell Study on anode and cathode catalysts

Direct Methanol Fuel Cell Study on anode and cathode catalysts. 曹殿学. Introduction. Direct methanol fuel cells Major problems facing DMFCs. Study on the anode electrocatalyst(Pt-Ru ad ). Study on the cathode electrocatalyst(Ru/Se). Acknowledgements. Direct Methanol Fuel Cell. e -. Load.

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Direct Methanol Fuel Cell Study on anode and cathode catalysts

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  1. Direct Methanol Fuel Cell Study on anode and cathode catalysts 曹殿学

  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 Cathode Anode 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. Sluggish anode kinetics a • Methanol crossoverc Key Issues Hindering the Development of Practical DMFCs: Ecel l= Ecell- ( a + c ) Ecell / Ecell<< 100% --过电势 • Develop active methanol electrooxidation catalysts. • Overcome methanol crossover issue.

  6. What I have done on the study of anode (University of Alberta, Canada)

  7. Pt Ru Best catalyst for CH3OH electrooxidation: PtRu nanoparticles • What is the optimum surface composition? • Best Pt:Ru ratio? •  Hard to measure surf. comp. • of nanoparticle PtRu. •  10~50% Ru was reported.

  8. Ru3+ H H H Pt Pt Pt # of Ru atom Pt/Ru comp.= # of surf. Pt atom 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

  9. 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.

  10. RE WE CE Ar in Ar out 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 Pt:Ru ~ 67:33

  11. Membrane Electrode Assembly (MEA) Anode: Pt-Ruad Cathode: Pt black Nanoparticle catalysts Nafionionomer Nafion-117

  12. Nafion-117 Membrane [CF2]2 [CF2]2 [CF2]2 [CF2]2 SO3- SO3- SO3- H2O SO3- H+ H+ H2O CH3OH H+ H2O H+ CH3OH H2O H2O H2O H2O H+ H2O CH3OH H+

  13. Ink Preparation (sonication) Hot-Pressing (125oC, 1500psig) Painting Steel plate Catalyst layer Paint brush Nafion-117 membrane Teflon tape Teflon decal Catalyst / Water / Nafion Fuel Cell Hardware Membrane Electrode Assembly

  14. T = 60oC, Pt:Ru ~ 65:35 T = 90oC, Pt:Ru ~ 50:50

  15. RE WE CE Ar in Ar out CVs for fresh Pt-Ruad

  16. CE RE WE H2 (H2O) Anode Pt-Ruad Cathode Pt CVs measured in fuel cells H2O (Ar)

  17. Is Pt-Ruad stable? (Ruad might come off) Fuel Cell Stability Test

  18. What I have done on the study of cathode (University of Illinois, USA)

  19. Anode Cathode CH3OH O2 + e- H2O CH3OH Nafion membrane CO2 + e- 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.

  20. Oxygen Reduction Reaction Activity Comparison Ru/Se 旋转电极 Methanol Tolerance

  21. 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) .

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