Defect‐Tolerant and Scalable Diffusio–Osmotic Power Generation with Sulfonated Covalent Organic Framework Membrane

Salinity gradient energy extracted with the reverse electrodialysis technique is attracting great interest and has been suggested as a promising renewable and stable energy source. However, the reverse electrodialysis relies on highly charge-selective membranes, causing a range of problems including the selectivity-permeability trade-off, strong concentration polarization, and strict requirement on the material structure, severely limiting its viability for large scale applications. We demonstrate these problems may be addressed by adopting the diffusio-osmosis process to generate power using sulfonated covalent framework membranes (COF), which does not require any charge selectivity. As a result, the membrane shows much higher power density compared to similar-sized membranes and enables much higher scalability. Remarkably, the generator has loose requirement on material structure and could largely maintain its power generation performance even when a substantial number of pinholes are present. This could make the material fabrication significantly easier than before. We expect our work to advance the practical application of salinity gradient energy extraction.