Bifunctional Chelating Resin-Modified Polymer Membrane for Sustainable Osmotic Energy Generation

Ion-selective membrane-based reverse electrodialysis (RED) has the potential to convert osmotic energy into electricity, offering a promising solution to complement the global renewable energy supply. However, the development of scalable, eco-friendly, polymer-based ion-selective membranes that achieve both high power density and long-term stability remains a crucial challenge. In this study, we present a stable mixed matrix membrane (MMM) by incorporating a bifunctional chelating resin into a polyvinyl chloride (PVC) membrane to enhance cation conduction. The introduction of phosphonic and sulfonic acid-functionalized ion-selective resins, which exhibit a high affinity for metal ions due to the presence of abundant oxygen atoms, significantly improves both ion conduction and selectivity. As a result, the mixed matrix membrane achieves a remarkable power density of 26.5 W/m2 under a 500-fold salt gradient, and a real-world output power of 8.80 W/m2 is generated at the interface of natural seawater and freshwater. The MMM fabrication offers a viable, cost-effective, and scalable approach for enhancing osmotic energy conversion in ion-selective polymers, paving the way for its application in sustainable energy harvesting, redox flow batteries, and ion separation technologies.