Radiation induced grafting; Reactive oxygen species; Antioxidant; Fuel cell; Radical scavenger; Proton exchange membrane
Gubler Lorenz, Koppenol Willem H. (2017), Hydrocarbon Proton Exchange Membranes, in Schlick Shulamith (ed.), John Wiley & Sons, -, 107-138.
Buchmüller Yves, Zhang Zhuoxiang, Wokaun Alexander, Gubler Lorenz, Antioxidants in non-perfluorinated fuel cell membranes: prospects and limitations, in RSC Advances
, 4, 51911-51915.
Buchmüller Yves, Hafner Regina, Wokaun Alexander, Schmidt Thomas J., Gubler Lorenz, From Electrochemical Interface to Interphase (2D->3D) on Ionomer Membranes, in ChemElectroChem
, 2, 338-342.
Buchmüller Yves, Wokaun Alexander, Gubler Lorenz, Fuel CellMembranes Based on Grafted and Post-Sulfonated Glycidyl Methacrylate (GMA), in Fuel Cells
, 13(6), 1177-1185.
Zhuoxiang Zhang, Raphaël Chattot, Lukas Bonorand, Kaewta Jetsrisuparb, Yves Buchmüller, Alexander Wokaun, Lorenz Gubler, Mass spectrometry to quantify and compare the gas barrier properties of radiation grafted membranes and Nafion(R), in Journal of Membrane Science
, 472, 55-66.
Buchmüller Yves, Wokaun Alexander, Gubler Lorenz, Polymer-bound Antioxidants in Grafted Membranes for Fuel Cells, in Journal of Materials Chemistry A
, 2(16), 5870-5882.
The scientific vision of this project is the incorporation of regenerative antioxidant functional-ities into proton conducting membranes used in fuel cells to protect the ionomer against oxi-dative stress, which is caused by reactive oxygen species (ROS), such as HO• and HOO•, prevalent in the H2/O2 fuel cell as intermediates. Although the technology of the polymer electrolyte fuel cell (PEFC) has come a long way in the past two decades and reached prototype and pre-commercial level, the reliability and stability of the used components and materials are still insufficient for high-revenue markets, e.g. electric vehicle applications with highly dynamic operating conditions. It has been established that chemical degradation of fuel cell membranes is caused by oxygen radical species, which are formed in the fuel cell as a result of the interaction of H2, O2 and the Pt catalyst. Effective mitigation of oxidative stress is a key to improving chemical stability and membrane lifetime.The approach taken in this project is aimed at the incorporation of organic redox couples as antioxidant functionalities, which are introduced to the membrane via radiation induced graft copolymerization, a technique which we have optimized over the past years for the prepara-tion of fuel cell membranes. The antioxidant units are intended to react with the aggressive oxygen radicals to mitigate or prevent oxidative degradation. Due to the constant bombard-ment of the ionomer with ROS, it is essential that the antioxidant functionalities, once spent, be restored to their reduced state to act again as radical scavengers. This reduction reaction is envisioned to be driven by the reductive power of the fuel cell anode. For the electrochemi-cal reaction to be effective within the bulk of the ionomer membrane, the redox units buried within the membrane will be electrically ‘wired’ to the anode through the incorporation of a conductive polymer.In a further aspect of the work, the creation of spatially confined antioxidant regions (‘barrier’ layer) will be investigated via surface grafting. Characterization of the membranes will involve the analysis of composition, fuel cell relevant properties (e.g. proton conductivity), and chemical stability in ex situ tests as well as in situ evaluation in fuel cells using accelerated aging test protocols.