Constructing a dual strategy of hydrophilic nanochannel and multiscale porosity in multi-level PES/SPSf hybrid membrane for enhancing water vapor selectivity

Membrane humidification remains a key concern for proton exchange membrane fuel cell (PEMFC), yet sulfonated polymer membranes like SPEEK, which suffer from excessive swelling and mechanical degradation under high-humidity operation. In this study, a multiscale porous PES/SPSf hybrid humidified membrane with rigid PES backbone and -SO 3 H functionality is fabricated via phase inversion. The porous substructure promotes capillary condensation, while the hydrophilic structure domains enhance water adsorption and diffusion. Compared to pure M0 membrane, the M30-6 membrane achieves a water vapor permeability of 2917 GPU and a water vapor/N 2 selectivity of 1307, representing 59% and 686% enhancements, respectively. The synergistic effect between hydrophilic -SO 3 H group and the multiscale porosity structure demonstrates the potential of these membrane designs to strengthen the PEMFCs' humidification.