Evaluation of Nanopore Model

An obvious approach in evaluating the nanopore model would involve a measurement of the proton conductivity of a nanoporous layer with charged metallic walls as a function of the applied voltage. Proton concentration in a conductive nanoporous membrane is a function of (pP . Assuming bulk-like proton transport, the variation of 

FIG U RE 3.28 The impact of pore length and metal charging properties on the pore effectiveness factor Tpore For a reference set parameter with = 0.7 V versus SHE, Rp = 5 nm, and 

An initial evaluation of the nanopore model can be conducted by comparison with electrochemical performance data for MEAs that utilize UTCLs on the cathode side. The two types of experimental materials considered are nanoporous gold leafs plated with varying amounts of Pt (Pt-NPGL) (Zeis et al., 2007) and Pt NSTF layers of 3M (Pt-NSTF) (Debe et al., 2006). 

A simple scale-up procedure gives the relation between UTCL overpotential r]c and fuel cell current density jo. 

For simplification, UTCLs are assumed to be composed of cylindrical water-filled pores with monodisperse Rp and Lp. The potential of zero charge, is considered as an adjustable parameter. Further input parameters needed in the model include RpEM and kinetic parameters of the ORR, namely, / +, and ac (Bonakdarpour et al., 2007 Sarapuu et ak, 2008). 

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