Improvement in direct methanol fuel cell performance by treating the anode at high anodic potential

• Published in: Journal of power sources Vol. 245; pp. 37 - 47
• Main Authors: JOGHEE, Prabhuram, PYLYPENKO, Svitlana, WOOD, Kevin, CORPUZ, April, BENDER, Guido, DINH, Huyen N, O'HAYRE, Ryan
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier 2014
• Subjects: Agglomerates; Anodes; Anodic; Applied sciences; Catalysts; Direct energy conversion and energy accumulation; Electrical engineering. Electrical power engineering; Electrical power engineering; Electrochemical conversion: primary and secondary batteries, fuel cells; Energy; Energy. Thermal use of fuels; Equipments for energy generation and conversion: thermal, electrical, mechanical energy, etc; Exact sciences and technology; Fuel cells; Ionomers; Materials; Methyl alcohol; Performance enhancement; Performance evaluation; Ionomer; Polarization; Anode; Direct methanol fuel cell; Alcohol fuel cells; Long-term performance; Reorganization of Nafion ionomer; Electrode material; Potential; Anodic treatment; MOR polarization; Long term; Primary alcohol; Sulfonate copolymer; Tetrafluoroethylene copolymer; CO stripping voltammetry; Cation exchange membrane; Surface properties; Surface area; Performance; Methanol
• ISSN: 0378-7753; 1873-2755
• DOI: 10.1016/j.jpowsour.2013.06.105

This work investigates the effect of a high anodic potential treatment protocol on the performance of a direct methanol fuel cell (DMFC). DMFC membrane electrode assemblies (MEAs) with PtRu/C (Hi-spec 5000) anode catalyst are subjected to anodic treatment (AT) at 0.8 V vs. DHE using potentiostatic method. Despite causing a slight decrease in the electrochemical surface area (ECSA) of the anode, associated with ruthenium dissolution, AT results in significant improvement in DMFC performance in the ohmic and mass transfer regions and increases the maximum power density by similar to 15%. Furthermore, AT improves the long-term DMFC stability by reducing the degradation of the anode catalyst. From XPS investigation, it is hypothesized that the improved performance of AT-treated MEAs is related to an improved interface between the catalyst and Nation ionomer. Among potential explanations, this improvement may be caused by incorporation of the ionomer within the secondary pores of PtRu/C agglomerates, which generates a percolating network of ionomer between PtRu/C agglomerates in the catalyst layer. Furthermore, the decreased concentration of hydrophobic CF sub(2) groups may help to enhance the hydrophilicity of the catalyst layer, thereby increasing the accessibility of methanol and resulting in better performance in the high current density region.