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Generally, the kinetics of low$-$temperature fuel cells is described well by the Butler$-$ temperationed conditions. Assume that the change in enthalpy does not vary with Volmer equation. The oxygen reduction reaction $($ORR$)$ is highly irreversible, whereas the hydrogen oxidation $($HOR$)$ is fast. With the slow ORR kinetics, a large the hydrogen oxidation $($HOR$)$ is fast. With the slow ORR kinetics, a larg overpotential is needed to achieve any appreciable current. The following data are provided for the ORR in acid media at $80C.$ The potential of the positive electrode, ${}_1,$ is measured with provided for the ORR in acid media at $80C.$ The potential of the positive electrode, ${}_1,$ is measured with respect to a hydrogen reference electrode. Additionally, any ohmic resistance has been removed from the potentials tabulated. Please obtain the exchange current density and Please obtain the exchange current density and charge transfer coefficient for the ORR in the mid$-$current range $(15$ points$).$

In part $(2),$ why the small and high ranges of current densily estimate the kinetic parameters of ORR reaction $(5$ points$)?$

From an EIS characterization of the system at $400m\frac{A}{c}{m}^2,$ the following Nyquist diagram was produced. What would be the ionic conductivity of Nafion membrane with a thick

a thickness of $18m(10$ points$)?$ Use the experimental points $($blue dots$)$ for your measurements.

For this PEM fuel cell, is the current distribution uniform or non$-$uniform? Please justify $6.$ In PEMFCS younstatively $(5$ points$).q,$

efficiency. The study of mass transfer of uncharged species is important because it can lead to significant fuel cell performance losses if not understood properly. A standard way of cat

standard way of calculating fue be expressed by the equation:

${}_{\text{m}\text{a}\text{n}\text{e}}=$ constant $*ln(\frac{t_{\text{i}\text{s}\text{e}}}{t_{\text{l}\text{i}\text{s}}-i})$

constant $=\frac{RT}{nF}(1+\frac{1}{})$

For the PEM fuel cell, the majority of mas transfer loss happens at cathode as diffusivity

of oxygen is much smaller than that of hydrogen. Please determine the concentration overpotential at the cathode with a difusion layer thickness of $0\mathrm{.}001cm(10$ points$).$ The

$D_{0_2}=3\mathrm{.}5{10}^{-5}c\frac{m^2}{s}$

$D_{0_2}=3\mathrm{.}5{10}^{-5}c\frac{m^2}{s}7.$ Determine the overall full cell potential at the current density of $400mAlc{m}^2(15$

Determine points$).$

$q,$

$q,$

$q,$ Furthermore, it causes degradation effects and pinhale formation. Hence the hydrogen crossover represents a fundamental factor for the lifetime of a fuel cell and quantification of the quantification of the crossover is a key factor for mermbrane qualification. For the PEM fuel cell under this study, it is assumed that the hydrogen crossover current $10A*m^{-2}.$ Estimate the permeability for hydrogen throu the bulk concentration is $30\mathrm{.}000$mol$*m^{-3}(10$ points$).q,$

$q,$

$q,$

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$q,$

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$q,$

$q,$ charge required for monolayer adsorptionidesorption. Figure below shows a typical $CV$ voltammogram of the hydrogen adsorption$/$desorption $($HAD$)$ reaction. CV voltammogram of the hydrogen adsorptionidesorption $($HAD$)$ reaction.

The process of interest is the electroreduction of protons and adsorption of hydragen interest.