1. 1 DIRECT METHANOL FUEL CELL WITH EXTENDED REACTION ZONE ANODE Alex Bauer, Elöd L. Gyenge and Colin W. Oloman Department of Chemical and Biological Engineering The University of British Columbia, Vancouver, Canada Presented by: Alex Bauer Date: 2 nd of November 2006 210 th Meeting of The Electrochemical Society Cancun, Mexico

2. 2 @ 298 K Anode reaction: CH 3 OH + H 2 O  CO 2 + 6H + + 6e - E 0 a = 0.04 V @ 298 K Methanol: - cheap (ca. 200 $ US/t) Methanol: - cheap (ca. 200 $ US/t) - easy handling, storage and distribution - easy handling, storage and distribution - simple fuel cell design and operation - simple fuel cell design and operation DMFCs for portable applications (and transportation) Fuel Volumetric Energy Density kWh l -1 Hydrogen (30 MPa) 0.75 Hydrogen (liquid, T=20K) 2.36 Gasoline 8.76 Methanol 4.42 [1] W. Zittel, R. Wurster, HyWeb: Knowledge – Hydrogen in the Energy Sector http://www.hydrogen.org/Knowledge/w-i-energiew-eng2.html [1]

3. 3 Sluggish anode reaction  Development of novel catalysts (ternary and quaternary compositions)  Enhancing active catalyst area (nanoparticle – support interaction) Methanol cross-over  Modified membranes CO 2 accumulation  Hydrophobic channels (PTFE addition)  Alternative flow designs (e.g. mesh flow beds)  Novel electrode designs Current challenges and potential solutions OUR APPROACH: Application of porous 3D catalyzed graphite felt electrode with high specific surface area

4. 4 Recent developments for DMFC anode designs [2] G. S. Chai et al., J. Phys. Chem. B, 108, 7076 (2004) [3] R. G. Allen et al., J. Power Sources, 143, 145 (2005) Carbon Ti mesh 500 nm 100 nm PtRu particles d = 2 - 3 nm PtRu particles d  5 nm

5. 5 DMFC with conventional anode Anode reaction: CH 3 OH + H 2 O → CO 2 + 6H + + 6e - Cathode reaction: 1.5O 2 + 6H + + 6e - → 3H 2 O CH 3 OH (l) O 2 (g) H+H+ e-e- 15-50  m 100-300  m end plate diffusion layer catalyst layer membrane

6. 6 DMFC with novel 3D anode Anode reaction: CH 3 OH + H 2 O → CO 2 + 6H + + 6e - CH 3 OH (l) H+H+ 100-200  m depending on compression O 2 (g) e-e- catalyzed graphite felt Cathode reaction: 1.5O 2 + 6H + + 6e - → 3H 2 O

7. 7 2-15 nm [4] B. Gollas et al., Electrochimica Acta, 45 (22), 3712 & 3721 (2000) [4] Surfactant assisted electrodeposition to obtain porous catalyst deposits [5] A. Bauer et al., Electrochimica Acta, 51 (25), 5359 (2006) Without surfactant With surfactant Smooth substrate 3D graphite substrate [5][5]

8. 8 Surfactant assisted galvanostatic deposition of nanoparticles on 3D substrate graphite felt substrate + - DC power supply platinized Titanium anodes graphite felt (cathode) plexiglass cell containing plating solution plastic mesh separator   0.95, d  350  m, a s  10 4 m -1 [6] A. Bauer et al., Electrochimica Acta, 51 (25), 5358 (2006) [6]

9. 9 Research objectives Surfactant mediated electrodeposition of PtRu and PtRuMocatalyst on graphite felt Surfactant mediated electrodeposition of PtRu and PtRuMocatalyst on graphite felt Analysis of deposit morphology, weight, composition Analysis of deposit morphology, weight, composition and active surface area (SEM, ICP_AES, Cu upd) Assessment of catalytic activity for methanol oxidation (CV,CP,CA) Assessment of catalytic activity for methanol oxidation (CV,CP,CA) Fuel cell testing Fuel cell testing Overall goal: Overall goal: Assess feasibility of employing catalyzed graphite felt as Assess feasibility of employing catalyzed graphite felt as DMFC anode for liquid feed operation. DMFC anode for liquid feed operation.

10. 10 Results - SEM High resolution SEM micrograph of PtRu catalyst deposited on graphite by surfactant assisted galvanostatic plating ► ◄ ~ 50 nm

11. 11 Results – Cyclic voltammetry Scan rate = 5 mV s -1, 0.5 M CH 3 OH - 0.1 M H 2 SO 4

12. 12 Results – Chronopotentiometry Current = 5 mA cm -2, 0.5 M CH 3 OH - 0.1 M H 2 SO 4

13. 13 Results – FC tests: Novel 3D anode vs. conventional gas diffusion electrode (GDE) Anode: 1 M CH 3 OH - 0.5 M H 2 SO 4, 5 ml min -1, ambient pressure Cathode: dry O 2, 500 ml min -1 STP, 2 atm

14. 14 Anode: 1 M CH 3 OH - 0.5 M H 2 SO 4, 5 ml min -1, ambient pressure Cathode: dry O 2, 500 ml min -1 STP, 2 atm Results – FC tests: Novel 3D anode vs. conventional gas diffusion electrode (GDE)

15. 15 Anode: 1 M CH 3 OH - 0.5 M H 2 SO 4, 5 ml min -1, ambient pressure Cathode: dry O 2, 500 ml min -1 STP, 2 atm Results – FC tests: Novel 3D anode PtRu vs. PtRuMo

16. 16 Anode: 1 M CH 3 OH - 0.5 M H 2 SO 4, 5 ml min -1, ambient pressure Cathode: dry O 2, 500 ml min -1 STP, 2 atm Results – FC tests: Novel 3D anode PtRu vs. PtRuMo

17. 17 gel: 1 M H 2 SO 4, 5 % wt SiO 2 Results – Deactivation tests in fuel cell Anode: 1 M CH 3 OH - 0.5 M H 2 SO 4, 5 ml min -1, ambient pressure Cathode: dry O 2, 500 ml min -1 STP, 2 atm i = 400 mA cm -2 T = 353 K

18. 18 [7] C. Coutanceau et al., J. Appl. Electrochem., 34, 64 (2004) [8] G. S. Chai et al., J. Phys. Chem. B, 108, 7078 (2004) [9] R. G. Allen et al., J. Power Sources, 143, 148 (2005) Comparison of fuel cell performance with standard MEA and published data

19. 19 Conclusions and outlook Obtained highly dispersed nanoparticles on 3D substrate Obtained highly dispersed nanoparticles on 3D substrate Improved performance compared to conventional GDE Improved performance compared to conventional GDE (e.g. power output increased by 38 % at 300 mA cm -2 ) (e.g. power output increased by 38 % at 300 mA cm -2 ) Proof of concept for novel electrode design Proof of concept for novel electrode design Future work: Future work: Optimize FC operation conditions Optimize FC operation conditions (experimental design) (experimental design) Develop ionic conductor network Develop ionic conductor network Improve long term performance - especially for PtRuMo Improve long term performance - especially for PtRuMo (e.g. catalyst regeneration after 2 h) (e.g. catalyst regeneration after 2 h)

20. 20 The authors gratefully acknowledge the financial support of the BC Advanced Systems Institute and the Natural Sciences and Engineering Research Council of Canada. Acknowledgements