PEMFC(Proton Exchange Membrane Fuel Cells)에서 PtCo/C 합금 촉매가 성능이나 내구성에서 우수하여 많이 사용 되고 있다. 그러나 높은 전압에서(1.0~1.5 V) 평가되는 촉매 지지체 내구성에 관한 연구는 별로 보고 되지 않았다. 본 연구에서는 PtCo/C 촉매와 Pt/C 촉매에 촉매 지지체 가속 열화 프로토콜을 적용한 후 내구성을 비교하였다. 1.0↔1.5 V 전압 변화 사이클 반복 후에 촉매 비활성도(Mass activity)와 전기화학적 활성면적(ECSA), 전기이중층 용량(DLC), Pt 용해와 입자 성장 등을 분석하였다. 전압변화 2,000 사이클 후 PtCo/C 촉매는 Pt/C 촉매에 비해 0.9 V에서 촉매 무 게당 전류밀도가 1.5배 이상 감소하였다. 이와 같은 결과는 PtCo/C 촉매의 카본지지체의 열화 속도가 Pt/C 촉매보다 높기 때문이었다. Pt/C 촉매는 PtCo/C 촉매보다 촉매층의 ECSA 감소가 1.5배 이상 높았지만 Pt/C 촉매의 카본 지지 체 부식이 작아 I-V 성능 감소가 작았다. PtCo/C 촉매의 고전압 내구성 향상을 위해서는 카본 지지체 내구성 향상이 필수적임을 보였다.

In PEMFC, PtCo/C alloy catalysts are widely used because of good performance and durability. However, few studies have been reported on the durability of carbon supports of PtCo/C evaluated at high voltages (1.0~1.5 V). In this study, the durability of PtCo/C catalysts and Pt/C catalysts were compared after applying the accelerated degradation protocol of catalyst support. After repeating the 1.0↔1.5V voltage change cycles, the mass activity, electrochemical surface area (ECSA), electric double layer capacitance (DLC), Pt dissolution and the particle growth were analyzed. After 2,000 cycles of voltage change, the current density per catalyst mass at 0.9V decreased by more than 1.5 times compared to the Pt/C catalyst. This result was because the degradation rate of the carbon support of the PtCo/C catalyst was higher than that of the Pt/C catalyst. The Pt/C catalyst showed more than 1.5 times higher ECSA reduction than the PtCo/C catalyst, but the corrosion of the carbon support of the Pt/C catalyst was small, resulting in a small decrease in IV performance. In order to improve the high voltage durability of the PtCo/C catalyst, it was shown that improving the durability of the carbon support is essential.

PEMFC Catalyst support PtCo/C catalyst Degradation Durability test

1. Gittleman, C. S., Kongkanand, A., Masten, D., and Gu, W.,“Materials Research and Development Focus Areas for Low
Cost Automotive Proton-exchange Membrane Fuel Cells,” Curr.Opin. Electrochem., 18, 81(2019).
2. Borup, R. L., Kusoglu, A., Neyerlin, K. C., Mukundan, R.,Ahluwalia, R. K., Cullen, D. A., More, K. L., Weber, A. Z. and Myers, D. J., “Recent Developments in Catalyst-related PEM Fuel Cell Durability,” Curr. Opin. Electrochem., 21, 192(2020).
3. Marcinkoski, J., Vijayagopal, R., Adams, J., James, B., Kopasz,J. and Ahluwalia, R., Hydrogen Class 8 Long Haul Truck Targets. Subsection of the Electrified Powertrain Roadmap. Technical Targets for Hydrogen-Fueled Long-Haul Tractor-Trailer Trucks.https://hydrogen.energy.gov/pdfs/19006_hydrogen_class8_long_haul_truck_targets.pdf.
4. Borup, R. et al., “Scientific Aspects of Polymer Electrolyte Fuel Cell Durability and Degradation,” Chem. Rev., 107, 3904(2007).
5. Watanabe, M., Tsurumi, K., Mizukami, T., Nakamura, T. and Stonehart, P., “Activity and Stability of Ordered and Disordered Co-Pt Alloys for Phosphoric Acid Fuel Cells,” J. Electrochem.Soc., 141(10), 2659-2668(1994).
6. Akita, T., Taniguchi, A., Maekawa, J., Siroma, Z., Tanaka, K.,Kohyama, M. and Yasuda, K., “Analytical TEM Study of Pt Particle Deposition in the Proton-exchange Membrane of a Membrane elctrode-Assembly,” J. Power Sources, 159(1), 461-467(2006).
7. Zhai, Y., Zhang, H., Xing, D. and Shao, Z., “The Stability of Pt/C Catalyst in H3PO4/PBI PEMFC During High Temperature Life Test,” J. Power Sources, 164(1), 126-133(2006).
8. Sharma, R. and Andersen, S. M.,“An Opinion on Catalyst Degradation Mechanisms During Catalyst Support Focused Accelerated Stress Test (AST) for Proton Exchange Membrane Fuel Cells (PEMFCs),” Applied Catalysis B: Environmental, 239, 636-643(2018).
9. Kaddouri, A. E., Flandin, L. and Bas, C., “Chemical Degradation of PFSA Ionomer Binder in PEMFC’s Catalyst Layer,” Int. J.Hydrogen Energy, 43, 15386-15397(2018).
10. Morawietz, T., Handl, M., Oldani, C., Gazdzicki, P., Hunger, J.,Wilhelm, F., Blake, J., Friedrich, K. A. and Hiesgen, R., “HighResolution Analysis of Ionomer Loss in Catalytic Layers after Operation,” J. Electrochem. Soc., 165(6) F3139-F3147(2018).
11. https://www1.eere.energy.gov/hydrogenandfuelcells/fuelcells/pdfs/component_durability_profile.pdf, “Doe Cell Component Accelerated Stress Test Protocols for Pem Fuel Cells.”
12. Daido University, Ritsumeikian Univ., Tokyo Institute of Technology, Japan Automobile Research Ins., “Cell Evaluation and Analysis Protocol Guidline,” NEDO, Development of PEFC Technologies for Commercial Promotion-PEFC Evaluation Project, January 30(2014).
13. Kim, M., Jung, N., Eom, K. S., Yoo, S. J., Kim, J. Y., Jang, J. H.,Kim, H. J., Hong, B. K. and Cho, E. A.,“Effects of Anode Flooding on the Performance Degradation of Polymer Electrolyte Membrane Fuel Cells,” J. Power Sources, 266, 332-340(2014).
14. Yoo, D. G., Kim, H. S., Oh, S. H. and Park, K. P., “Durability Evaluation of Cathode Open-type Proton Exchange Membrane
Fuel Cells Stacks,” Korean Chem. Eng. Res., 61(1), in print(2023).15. Yumiya, H., Kizaki, M. and Asai, H., “Toyota Fuel Cell System
(TFCS),” World Electric Vehicle Journal, 7, 85(2015).
16. Banham, D. and Ye, S., “Current Status and Future Development of Catalyst Materials and Catalyst Layers for Proton Exchange Membrane Fuel Cells: An Industrial Perspective,” ACS Energy Lett., 2, 629(2017).
17. Oh, S. H., Yoo, D. G., Kim, M. H., Park, J. Y. and Park, K. P.,“Effect of Pt-Co/C Cathode Catalyst on Electrochemical Durability of Membrane in PEMFC,” Korean Chem. Eng. Res., 61(1),in print(2023).
18. Sharma, R. and Andersen, S. M., “Membrane Fuel Cell Catalyst Layers during an Accelerated Stress,” ACS Catal, 8, 3424-3434(2018).
19. Ahluwalia, R. K., Papadias, D. D., Kariuki, N. N., Peng, J.-K.,Wang, X., Tsai, Y., Graczyk, D. G. and Myers, D. J., “Potential Dependence of Pt and Co Dissolution from Platinum-cobalt Alloy PEFC Catalysts Using Time-resolved Measurements,” J. Electrochem. Soc., 165, F3024(2018).
20. Kim, T., Lee, H., Sim, W., Lee, J., Kim, S., Lim, T. and Park, K.,“Degradation of Proton Exchange Membrane by Pt Dissolved/deposited in Fuel Cells,” Korean J. Chem. Eng., 26(5), 1265-1271(2009).