Effect of Particle Size and Operating Conditions on Pt3Co PEMFC Cathode Catalyst Durability

Catalysts

Mallika Gummalla²  Sarah C. Ball⁴  David A. Condit²  Somaye Rasouli³  Kang Yu³  Paulo J. Ferreira³  Deborah J. Myers¹  Zhiwei Yang² 

[1] Chemical Sciences and Engineering Division, Argonne National Laboratory, Lemont, IL 60439, USA; E-Mail:;United Technologies Research Center, East Hartford, CT 06108, USA; E-Mail:;Materials Science and Engineering Program, University of Texas, Austin, TX 78712, USA; E-Mails:;Johnson Matthey Technology Centre, Blounts Court, Sonning Common, Reading RG4 9NH, UK; E-Mail:

关键词: Pt₃Co catalyst;    PEM fuel cells;    in-cell performance;    catalyst durability;   

DOI  :  10.3390/catal5020926

来源: mdpi

【 摘 要 】

The initial performance and decay trends of polymer electrolyte membrane fuel cells (PEMFC) cathodes with Pt₃Co catalysts of three mean particle sizes (4.9 nm, 8.1 nm, and 14.8 nm) with identical Pt loadings are compared. Even though the cathode based on 4.9 nm catalyst exhibited the highest initial electrochemical surface area (ECA) and mass activity, the cathode based on 8.1 nm catalyst showed better initial performance at high currents. Owing to the low mass activity of the large particles, the initial performance of the 14.8 nm Pt₃Co-based electrode was the lowest. The performance decay rate of the electrodes with the smallest Pt₃Co particle size was the highest and that of the largest Pt₃Co particle size was lowest. Interestingly, with increasing number of decay cycles (0.6 to 1.0 V, 50 mV/s), the relative improvement in performance of the cathode based on 8.1 nm Pt₃Co over the 4.9 nm Pt₃Co increased, owing to better stability of the 8.1 nm catalyst. The electron microprobe analysis (EMPA) of the decayed membrane-electrode assembly (MEA) showed that the amount of Co in the membrane was lower for the larger particles, and the platinum loss into the membrane also decreased with increasing particle size. This suggests that the higher initial performance at high currents with 8.1 nm Pt₃Co could be due to lower contamination of the ionomer in the electrode. Furthermore, lower loss of Co from the catalyst with increased particle size could be one of the factors contributing to the stability of ECA and mass activity of electrodes with larger cathode catalyst particles. To delineate the impact of particle size and alloy effects, these results are compared with prior work from our research group on size effects of pure platinum catalysts. The impact of PEMFC operating conditions, including upper potential, relative humidity, and temperature on the alloy catalyst decay trends, along with the EMPA analysis of the decayed MEAs, are reported.

【 授权许可】

CC BY   
© 2015 by the authors; licensee MDPI, Basel, Switzerland.