Ce-UiO-66 Loaded Composite Membrane for Enhanced Proton Conductivity and Performance in Electrochemical Hydrogen Pumps via Recasting Method

Electrochemical hydrogen pump (EHP) holds significant promise for industrial byproduct hydrogen purification, where efficient proton conduction is critical. In this study, a cerium-based metal–organic framework-doped composite membrane is successfully prepared via a recasting method. Compared to the Nafion membrane, the composite membrane exhibits a slight decrease in ion-exchange capacity but a significant improvement in water uptake, leading to enhanced membrane hydration. On one hand, the composite membrane features larger and more uniformly distributed ionic clusters, with continuous hydrated domains facilitating better connectivity of ionic channels, thereby enabling more efficient proton transport. On the other hand, the higher free water content promotes the formation of a continuous hydrogen-bonded network, contributing to its superior proton conductivity. Under 80 °C and 100% relative humidity, the composite membrane achieves a proton conductivity of 148.53 mS/cm, representing a 34.7% improvement over Nafion. Consequently, EHP performance is significantly enhanced across varying hydrogen purity levels while maintaining stable long-term operation.