Effect of cations (Na+, Co2+, Fe3+) contamination in Nafion membrane: A molecular simulations study

The cation contamination is an important reason for the degradation of performance and durability of Nafion membrane, but the contamination mechanism for cations with different valence in Nafion membranes at different water content was not revealed at the microscale. In this study, the molecular dynamics simulations are performed to study the effect of the contamination of cations with various valence (Na+, Co2+, Fe3+) on the Nafion membrane at different water content. The mechanism for the degradation of the membrane performance in the presence of cations has been clarified. Moreover, it is found that cations with high valence have more serious negative impact on the connectivity of water clusters and the rearrangement of hydrogen bond network. This study provides a fundamental and comprehensive insight into the mechanism of the cation contamination in Nafion membrane, which is useful for the design of high durable ion exchange membranes.