Active layer of an electrode with polymer electrolyte: Estimation of platinum utilization degree

A specific feature of the electrode active layer with polymer electrolyte consists in the fact that the current generation process can occur only on the condition of the direct contact of the catalyst support (carbon black) particles with Nafion. However, in reality, the support particle agglomerates (grains) contact the Nafion particle agglomerates (grains). Therefore, one must expect a low catalyst (platinum) utilization degree. A hypothesis is offered that a fractal film of Nafion is formed on the surface of the support grain pores in the case of manufacturing the “catalytic ink” used to form the active layer. It can significantly increase the platinum utilization degree. A detailed computer simulation of the process of Nafion penetration into the support grain pores is performed. Factors are established allowing reaching a high platinum utilization degree. The data of computer simulation agree with the experimental estimates of platinum utilization degree.