  This paper is devoted to study the electrochemical behavior of Pt catalyst in
a polymer electrolyte fuel cell at various operating conditions and at
different electric potential difference (also known as voltage) cycling applied
in accelerated stress tests. The degradation of platinum is considered with
respect to the Pt ion dissolution and the Pt oxide coverage of catalyst
described by a one-dimensional model. In the model, degradation rate increases
with temperature and decreasing particle diameter of Pt nano-particles. The
theoretical study of the underlying diffusion system with the nonlinear
reactions is presented by analytical methods and gives explicit solutions
through a first integral of the ODE system. Numerical tests are obtained using
a second order implicit-explicit scheme. The computer simulation shows that the
lifetime of the catalyst depends on the voltage profile and the upper potential
level. By this Pt mass loss is more significant at the membrane surface than at
the gas diffusion layer.
