
335Fuel Cell Characterization
when the wafer thickness is less than half the probe spacing (t < s/2). For
thicker layer (t ≥ s/2), the bulk resistivity is calculated as
ρ
=
t
ts
ts
E
I
ln
sinh( )
sinh( )
/
/
-cm
2
Ω
. (8.23)
It is important to know as much about the structure of the electrode as pos-
sible to determine how to improve its efciency for carrying out the electro-
chemical reaction. As listed in Table 8.2 electrochemical, optical, radiation,
and physical methods are employed to characterize electrodes and electro-
catalysts. Various techniques including transmission electron microscopy
(TEM), x-ray diffraction (XRD), neutron radiography, spec ...