Interactions between Nafion ® ionomer and catalyst / support materials 12/ Shuang Ma Andersen KBM, SDU

A short history of PEMFC  The first application of PEMFC: 1960s in the Gemini space flights. Catalyst supports [1] Eelectrode depositon method [2] Polymer impregnation [3, 4]..... [1] Petrow H. G. et al. U.S. Pat. No. 4,166,143, [2] Wei Z.D,. et al., Electrochim. Acta –2287, [3] E.A. Ticianelli, Electrochem. Soc –2214, [4] M.S. Wilson, et al. US Pat. No. 6,300,000,  Major advance in the technology: 1980s significant reconfiguration of fundamental design to reduce Pt loading

MEA & TPB

Langmuir adsorption isotherm N is the total number of sites θ is surface coverage ratio Rate of adsorption Rate of desorption

Hyperbl function

Preparation  Sample size: ~ 20 mg  Interaction cell: Standard Eppendorf micro tube 1.5 or 2 mL (polypropylene)  Mixing: ultrasonication (35C o, 15-30min) mechanical shacking (300 spm, 6 h, room temperature)  Separation: micro tube centrifuge (10 min, 13 krpm, room temperature)

Determination  Technique: 19 F nuclear magnetic resonance spectroscopy, Bruker, 400 MHz  Sample volume: 600 μ L (+ 20 μ L D 2 O + reference)  Reference compound  Measuring condition: ns=64, sw=300ppm nucleus O1p[ppm]=-140  Platform: Mester Nova

Reference compound

A typical 19 F-NMR spectrum

Carbon substrate K eq = Γ max = 2.07E-01 (g/g) K eq = Γ max = 9.63E-02 (g/g)

Noble metal catalyst K eq = Γ max = 1.76E-02 (g/g) K eq = 1.29 Γ max = 3.04E-02 (g/g)

Noble metal catalyst with carbon as support K eq = Γ max = 4.09E-02 (g/g) K eq = Γ max = 1.33E-01 (g/g)

Fitting for supported catalyst

Application  Interaction between Nafion ionomer and catalyst/catalyst support (for both fresh and aged samples)  Electrode optimization, mixing ratio among ingredients  Modification / degradation of electrode material surface properties  Combined information of wetting property, surface area and porosity.

Thanks for your attention!