The influence of the electrochemical stressing (potential step and potential-static holding) on the degradation of polymer electrolyte membrane fuel cell electrocatalysts

Journal Article · Mon Sep 01 04:00:00 EDT 2008 · Journal of Power Sources, 185(1):280-286

DOI:https://doi.org/10.1016/j.jpowsour.2008.07.008· OSTI ID:939590

Shao, Yuyan; Kou, Rong; Wang, Jun; Viswanathan, Vilayanur V; Kwak, Ja Hun; Liu, Jun; Wang, Yong; Lin, Yuehe

The understanding of the degradation mechanisms of electrocatalysts is very important for developing durable electrocatalysts for polymer electrolyte membrane (PEM) fuel cell. The degradation of Pt/C electrocatalysts under potential static holding conditions (at 1.2V and 1.4V vs. RHE) and potential step conditions with the upper potential of 1.4V for 150s and changing to lower potential limits (0.85V and 0.60V) for 30s in each period [denoted as Pstep(1.4V_150s-0.85V_30s) and Pstep(1.4V_150s-0.60V_30s), respectively] were investigated. The electrocatalysts and support were characterized with electrochemical voltammetry, transmission electron microscope (TEM) and X-ray photoelectron spectroscopy (XPS). Pt/C degrades much faster under Pstep conditions than that under potential static holding conditions. Pt/C degrades under the Pstep(1.4V_150s-0.85V_30s) condition mainly through the coalescence process of Pt nanopaticles due to the corrosion of carbon support, which is similar to that under the conditions of 1.2V and 1.4V potential static holding; however, Pt/C degrades mainly through the dissolution/loss and dissolution/redepostion process if stressed under Pstep(1.4V_150s-0.60V_30s). The difference in the degradation mechanisms is attributed to the chemical states of Pt nanoparticles: Pt dissolution can be alleviated by the protective oxide layer under the Pstep(1.4V_150s-0.85V_30s) condition and the potential static holding conditions. These findings are very important for understanding PEM fuel cell material degradation and are also useful for developing fast test method for screening durable catalyst support materials.

• Research Organization: Pacific Northwest National Laboratory (PNNL), Richland, WA (US), Environmental Molecular Sciences Laboratory (EMSL)
• Sponsoring Organization: USDOE
• DOE Contract Number: AC05-76RL01830
• OSTI ID: 939590
• Report Number(s): PNNL-SA-60970; 30506; EB4209000
• Journal Information: Journal of Power Sources, 185(1):280-286, Journal Name: Journal of Power Sources, 185(1):280-286 Journal Issue: 1 Vol. 185; ISSN JPSODZ; ISSN 0378-7753
• Country of Publication: United States
• Language: English

Related Subjects

30 DIRECT ENERGY CONVERSION
CARBON
CATALYST SUPPORTS
CHEMICAL STATE
COALESCENCE
CORROSION
DISSOLUTION
ELECTROCATALYSTS
ELECTROLYTES
ELECTRON MICROSCOPES
Environmental Molecular Sciences Laboratory
FUEL CELLS
MEMBRANES
OXIDES
PEM fuel cell
POLYMERS
X-RAY PHOTOELECTRON SPECTROSCOPY
corrosion
degradation
electrocatalyst
platinum