A facile synthetic strategy based on a water-based process is developed for the preparation of metal-organic framework (MOF)-derived materials by revisiting the hydrolyzed non-porous metal-organic frameworks (h-MOF). ...A facile synthetic strategy based on a water-based process is developed for the preparation of metal-organic framework (MOF)-derived materials by revisiting the hydrolyzed non-porous metal-organic frameworks (h-MOF). The poor water stability of MOF has been recognized as key limitations for its commercialization and large-scale applications because the hydrolysis resulted in the complete loss of their functionalities. However, we found that the negative effect of hydrolysis on MOF can be nullified during the heat treatment. As similar to the intact MOF, h-MOF can be used as a precursor for the preparation of MOF-derived materials from porous MOF-derived carbons (MDCs) to MDC@ZnO composites. The property of h-MOF-derived materials is almost equivalent to that of MOF-derived materials. In addition, h-MOF turned the weakness of water instability to the strength of facile water-based process for hybridization. With the demonstration of the hybrid composite between h-MDC@ZnO and reduced graphene oxide (rGO) as a prototype example, it exhibited superior electrochemical performance when evaluated as an electrode material for lithium-ion batteries.展开更多
Boron nitride nanotubes(BNNTs)show exceptional physical properties including high mechanical strength and thermal conductivity;however,their applications have been restricted due to limited dispersibility in processin...Boron nitride nanotubes(BNNTs)show exceptional physical properties including high mechanical strength and thermal conductivity;however,their applications have been restricted due to limited dispersibility in processing solvents.Here,a novel BNNT dispersion method with exceptional dispersibility in a wide range of solvents has been demonstrated by surtace polarity modulation through short-molecule pyridine attachment.Nitrogen atoms in pyridine are selectively bonded to electron-deficient boron atoms of the BNNT surface through Lewis acid-base reaction,which changes the surface polarity of BNNTs from neutral to negative.Re-dispersing pyridine-attached BNNTs(Py-BNNTs)create a thick and stable electronic double layer(EDL),resulting in uniform dispersion of BNNTs in solvents with an exceptional solubility parameter range of 18.5-48 MPa^1/2.The uniform dispersion of BNNTs is maintained even after the mixing with diverse polymers.Finally,composites incorporating uniformly-distributed BNNTs have been realized,and extraordinary property enhancements have been observed.The thermal conductivity of 20 wt.%Py-BNNT/epoxy composite has been significantly improved by 69.6%and the tensile strength of 2 wt.%Py-BNNT/PVA has been dramatically improved by 75.3%.Our work demonstrates a simple and facile route to dispersing BNNTs in diverse solvents,consequently leading to selective utlization of BNNT dispersed solvents in various application fields.展开更多
文摘A facile synthetic strategy based on a water-based process is developed for the preparation of metal-organic framework (MOF)-derived materials by revisiting the hydrolyzed non-porous metal-organic frameworks (h-MOF). The poor water stability of MOF has been recognized as key limitations for its commercialization and large-scale applications because the hydrolysis resulted in the complete loss of their functionalities. However, we found that the negative effect of hydrolysis on MOF can be nullified during the heat treatment. As similar to the intact MOF, h-MOF can be used as a precursor for the preparation of MOF-derived materials from porous MOF-derived carbons (MDCs) to MDC@ZnO composites. The property of h-MOF-derived materials is almost equivalent to that of MOF-derived materials. In addition, h-MOF turned the weakness of water instability to the strength of facile water-based process for hybridization. With the demonstration of the hybrid composite between h-MDC@ZnO and reduced graphene oxide (rGO) as a prototype example, it exhibited superior electrochemical performance when evaluated as an electrode material for lithium-ion batteries.
基金This study was supported financially by the Fundamental Research Program(PNK6050 and PNK6550)of the Korea Institute of Materials Science(KIMS).
文摘Boron nitride nanotubes(BNNTs)show exceptional physical properties including high mechanical strength and thermal conductivity;however,their applications have been restricted due to limited dispersibility in processing solvents.Here,a novel BNNT dispersion method with exceptional dispersibility in a wide range of solvents has been demonstrated by surtace polarity modulation through short-molecule pyridine attachment.Nitrogen atoms in pyridine are selectively bonded to electron-deficient boron atoms of the BNNT surface through Lewis acid-base reaction,which changes the surface polarity of BNNTs from neutral to negative.Re-dispersing pyridine-attached BNNTs(Py-BNNTs)create a thick and stable electronic double layer(EDL),resulting in uniform dispersion of BNNTs in solvents with an exceptional solubility parameter range of 18.5-48 MPa^1/2.The uniform dispersion of BNNTs is maintained even after the mixing with diverse polymers.Finally,composites incorporating uniformly-distributed BNNTs have been realized,and extraordinary property enhancements have been observed.The thermal conductivity of 20 wt.%Py-BNNT/epoxy composite has been significantly improved by 69.6%and the tensile strength of 2 wt.%Py-BNNT/PVA has been dramatically improved by 75.3%.Our work demonstrates a simple and facile route to dispersing BNNTs in diverse solvents,consequently leading to selective utlization of BNNT dispersed solvents in various application fields.
