Abstract
Proton exchange membrane (PEM) has been used in electrochemical systems such as fuel cells and water electrolysis. For the practical use of PEM, crossover is a significant issue. The crossover is a permeation of hydrogen gas through PEM, and it causes the decrease of current efficiency. Therefore, it is important to figure out the permeation mechanism and to develop a superior PEM that has a lower permeability. In this study, we developed a new measurement system for hydrogen solubility and diffusivity in PEM based on NMR technique. The system can detect hydrogen molecules in PEM through NMR signal and obtain directly both the solubility and diffusivity. We measured these properties in Nafion^[○!R]112 and 117. The hydrogen solubility showed a proportional relationship to ambient pressure, and its representative value was approximately 1.4×10^<-5>mol/cm^3 at 1.0MPa. The hydrogen diffusivity in Nafion^[○!R] was 2×10^<-10>m^2/s, which did not show pressure dependence up to 1.0MPa.
