Covalent organic framework nanosheets(CONs)with porous crystalline features and ultrathin thickness are ideal candidates as membrane building blocks to form well-defined transfer nanochannels.The formidable challenge ...Covalent organic framework nanosheets(CONs)with porous crystalline features and ultrathin thickness are ideal candidates as membrane building blocks to form well-defined transfer nanochannels.The formidable challenge behind self-supporting CONs membrane lies in weak noncovalent interlayer interactions and thus loose stacking,insufficient strength and structure stabilities.Herein,we propose the fabrication of interlayer force-strengthened freestanding CONs membrane through the electrostatic attraction bridge effect of positively-charged amino-rich CONs(CON-NH2)to negatively-charged sulfonated CONs(CON-SO_(3)H).Ultrathin and large lateral sized CON-SO_(3)H and CON-NH2 are synthesized,followed by restacking to prepare freestanding CONs membrane with CON-SO_(3)H as the membrane bulk.Benefiting from effective interlayer interconnection due to strong electrostatic interaction,the obtained CON-SO_(3)H/CON-NH2 membrane displays features of ultrahigh integrity,dense stacking,eminent water/acid/base/organic solvents stabilities and mechanical strength(109 MPa).The shortened-SO_(3)H distance contributes to construct site-continuous transfer pathways,and the deprotonated-SO_(3)H and protonated-NH2 form acid-base pairs to decrease interfacial resistance,which impart membrane superior proton conductivity of 486 mS cm^(-1)(80℃,100%RH).This interlayer force enhancement strategy offers a promising perspective on achieving densely-stacked CONs membrane with ultrahigh mechanical property and conduction performance for fuel cell application.展开更多
文摘Covalent organic framework nanosheets(CONs)with porous crystalline features and ultrathin thickness are ideal candidates as membrane building blocks to form well-defined transfer nanochannels.The formidable challenge behind self-supporting CONs membrane lies in weak noncovalent interlayer interactions and thus loose stacking,insufficient strength and structure stabilities.Herein,we propose the fabrication of interlayer force-strengthened freestanding CONs membrane through the electrostatic attraction bridge effect of positively-charged amino-rich CONs(CON-NH2)to negatively-charged sulfonated CONs(CON-SO_(3)H).Ultrathin and large lateral sized CON-SO_(3)H and CON-NH2 are synthesized,followed by restacking to prepare freestanding CONs membrane with CON-SO_(3)H as the membrane bulk.Benefiting from effective interlayer interconnection due to strong electrostatic interaction,the obtained CON-SO_(3)H/CON-NH2 membrane displays features of ultrahigh integrity,dense stacking,eminent water/acid/base/organic solvents stabilities and mechanical strength(109 MPa).The shortened-SO_(3)H distance contributes to construct site-continuous transfer pathways,and the deprotonated-SO_(3)H and protonated-NH2 form acid-base pairs to decrease interfacial resistance,which impart membrane superior proton conductivity of 486 mS cm^(-1)(80℃,100%RH).This interlayer force enhancement strategy offers a promising perspective on achieving densely-stacked CONs membrane with ultrahigh mechanical property and conduction performance for fuel cell application.
