Atomically thin two-dimensional membranes are promising for osmotic energy generation.However,the trade-off between permeability and selectivity remains a long-standing bottleneck.Herein,we demonstrate that a cationic...Atomically thin two-dimensional membranes are promising for osmotic energy generation.However,the trade-off between permeability and selectivity remains a long-standing bottleneck.Herein,we demonstrate that a cationic AB-stacking covalent-organic framework(COF)bilayer achieves high ion conductivity and selectivity.Through precise molecular design and the Langmuir-Blodgett(LB)technique,we fabricate an anion-selective COF bilayer(EB-COF)using tetradentate 4,40,400,4000-(porphyrin-5,10,15,20-tetrayl)tetrabenzaldehyde(TFPP)and bidentate ethidium bromide(EB)with a covalently tethered pyridinium moiety.The EB-COF bilayer shows a record-high output power density of 7,174 W m^(-2)(0.5/0.01 M NaCl),significantly outperforming the AA-stacking PDA-COF bilayer constructed with TFPP and neutral p-phenylenediamine(PDA).This exceptional performance stems from highly ordered sub-2-nm nanopores,exceptional pore utilization efficiency,and a large surface charge density of 4.4 mCm^(-2),which together synergistically enhance anion selectivity and ion permeability.This work not only provides fundamental insights into the structure-performance relationship of permselective membranes but also offers a promising strategy for high-efficiency osmotic energy harvesting.展开更多
基金support from the National Natural Science Foundation of China(grant nos.22125406 and 22074149 for P.Y.,22134002 for L.M.,and 22174146 for Y.J.)the Natural Science Foundation of Beijing(2242028 for W.M.and Z230022 for P.Y.)the National Basic Research Program of China(2022YFA1204500 and 2022YFA1204503)。
文摘Atomically thin two-dimensional membranes are promising for osmotic energy generation.However,the trade-off between permeability and selectivity remains a long-standing bottleneck.Herein,we demonstrate that a cationic AB-stacking covalent-organic framework(COF)bilayer achieves high ion conductivity and selectivity.Through precise molecular design and the Langmuir-Blodgett(LB)technique,we fabricate an anion-selective COF bilayer(EB-COF)using tetradentate 4,40,400,4000-(porphyrin-5,10,15,20-tetrayl)tetrabenzaldehyde(TFPP)and bidentate ethidium bromide(EB)with a covalently tethered pyridinium moiety.The EB-COF bilayer shows a record-high output power density of 7,174 W m^(-2)(0.5/0.01 M NaCl),significantly outperforming the AA-stacking PDA-COF bilayer constructed with TFPP and neutral p-phenylenediamine(PDA).This exceptional performance stems from highly ordered sub-2-nm nanopores,exceptional pore utilization efficiency,and a large surface charge density of 4.4 mCm^(-2),which together synergistically enhance anion selectivity and ion permeability.This work not only provides fundamental insights into the structure-performance relationship of permselective membranes but also offers a promising strategy for high-efficiency osmotic energy harvesting.
