The Impact of Sulphate Anions on the Catalyst Durability for PEMFC

Platinum based nanoparticles supported on high surface area carbons still remain the most used reference for the activity and durability of fuel cell catalysts. Usually, a catalyst thin film supported on a rotating disk electrode in a liquid electrolyte is connected in a three electrode electrochemical cell setup. This has been proven to be the best technique to predict the activity and durability of a catalyst in real fuel cell [1]. It has been proven that there are differences in activity between perchloric acid and sulphuric acid [2]. Recently, it has been shown that the sulphate anions are poisoning the catalyst surface which can give rise to different degradation mechanisms then from the studies in perchloric acid [3].

Taking into consideration that different research groups are characterising catalysts in either sulphuric acid or perchloric acid and there is proof of the difference in activity, this work is focused on emphasizing the difference between durability studies in perchloric and sulphuric acid as revealed by Fig. 1. In order to determine the impact of anions on the overall degradation a series of experiments conducted in perchloric acid, sulphuric acid and half MEA have been conducted. As a measure of the durability, Pt dissolution has been monitored by AAS of the electrolyte.

Fig. 1 ESA loss vs number of cycles in 0.5 M perchloric acid (red line) and sulphuric acid (black line). The degradation took place in a two compartment - three electrode electrochemical cell and the electrode was cycled between 0.05-1.3 VRHE at 0.2 V s^-1.

Acknowledgement

This work has been supported by the Danish PEMFC Catalysts for Boosted Activity and Enhanced Durability (Energinet. dk project no. 2011-1-10669).

References

[1] H. A. Gasteiger, D. R. Baker, R. N. C. Hydrogen Fuel Cells: Fundamentals and Applications; Wiley: Copenhagen, 2010

[2] Meier, J. C.; Galeano, C.; Katsounaros, I.; Topalov, A. A.; Kostka, A.; Schu, F.; Mayrhofer, K. J. J. ACS Catalysis 2012, 2, 832–843.

[3] K. Kodama, A. Shinohara, N. Hasegawa, K. Shinozaki, R. Jinnouchi, T. Suzuki, T. Hatanaka, Y. Morimoto ECS Transactions, 58 (1) 363-368 (2013)