Carboxylate-functionalized polymers of intrinsic microporosity for High-Performance Osmotic Power Conversion

Abstract

Harvesting sustainable osmotic power from salinity gradients using reverse electrodialysis (RED) holds significant importance for addressing the global energy crisis. However, developing membranes with both high ion selectivity and conductivity remains a major challenge in the field of RED. Addressing this issue, this study proposes a functionalization strategy based on Polymers of Intrinsic Microporosity (PIM-1), combining "template-directed porogenesis and in situ carboxylation". This strategy creates a hierarchical structure integrating 0.84 nm sub-nanometer sieving channels with a 1–5 µm macroporous network. This structure not only facilitates rapid ion transport but also ensures cation selectivity. Under a 50-fold salinity gradient, the membrane achieved a peak power density output of 10.34 W·m-2, surpassing previously reported sulfonated SPIM membranes, and exhibited less than 10% performance degradation during 48 hours of continuous operation. This study provides a new approach for developing high-performance membrane materials for osmotic power conversion through synergistic structure-function optimization.