Simulation experiments on the effect of freezing of carbon substrate catalyst

By adiabatic expansion due to the introduction of an evacuation process, the water drop of about 2 mm diameter were cooled to 243 K by forming ice drops at the triple point of water. The sublimation temperature of ice rapidly decreased 243 K within 60 s and remained constant for 80 s. Subsequently, it became room temperature in about 60 s and the water drop disappeared owing to sublimation. By repeating this process, carbon and catalyst were markedly altered. Transmission electron microscopy (TEM) based on in situ observation elucidated the freezing problem in polymer electrolyte fuel cell (PEFC). Structural alterations of carbon due to freezing were observed and discussed as the oxidation phenomenon of carbon.