Covalent organic frameworks (COFs): from design to applications

Ding, San‐Yuan; Wang, Wei

doi:10.1039/c2cs35072f

Cited by 3,325 publications

(2,014 citation statements)

References 149 publications

(270 reference statements)

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“…In spite of the development of new porous materials of exciting structure and chemistry, such as metal–organic frameworks126 or covalent organic frameworks,127 nanoporous carbons are still the adsorbents of choice in many applications involving separation processes. This is mainly due to their low costs and environmental inertness, for which new materials are still not found as being competitive.…”

Section: Applications Of the Photochemical Activity Of Nanoporous Carmentioning

confidence: 99%

Origin and Perspectives of the Photochemical Activity of Nanoporous Carbons

Bandosz

Ania

2018

Advanced Science

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Even though, owing to the complexity of nanoporous carbons' structure and chemistry, the origin of their photoactivity is not yet fully understood, the recent works addressed here clearly show the ability of these materials to absorb light and convert the photogenerated charge carriers into chemical reactions. In many aspects, nanoporous carbons are similar to graphene; their pores are built of distorted graphene layers and defects that arise from their amorphicity and reactivity. As in graphene, the photoactivity of nanoporous carbons is linked to their semiconducting, optical, and electronic properties, defined by the composition and structural defects in the distorted graphene layers that facilitate the exciton splitting and charge separation, minimizing surface recombination. The tight confinement in the nanopores is critical to avoid surface charge recombination and to obtain high photochemical quantum yields. The results obtained so far, although the field is still in its infancy, leave no doubts on the possibilities of applying photochemistry in the confined space of carbon pores in various strategic disciplines such as degradation of pollutants, solar water splitting, or CO2 mitigation. Perhaps the future of photovoltaics and smart‐self‐cleaning or photocorrosion coatings is in exploring the use of nanoporous carbons.

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Section: Applications Of the Photochemical Activity Of Nanoporous Carmentioning

confidence: 99%

Origin and Perspectives of the Photochemical Activity of Nanoporous Carbons

Bandosz

Ania

2018

Advanced Science

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“…13,14,15 COFs are formed via self--assembly of precursor building blocks, and one can manipulate the structural topology by selecting different building blocks, leading to excellent structure tunability. COFs have been extensively studied as adsorbents for gas storage applications.…”

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confidence: 99%

“…On the other hand, the two--dimensional covalent triazine COFs, so--called CTFs, display high chemical stability. 15 CTFs are ionothermally synthesized through a dynamic trimerization reaction, starting from cheap and abundant building blocks. 15,20 Here we explore computationally the potential of two--dimensional CTFs as ultrathin--film membranes for desalination, employing classical molecular dynamics (MD) simulation techniques 21 as implemented within the LAMMPs package.…”

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confidence: 99%

Two-dimensional covalent triazine framework as an ultrathin-film nanoporous membrane for desalination

2015

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We computationally demonstrate that two--dimensional covalent traizine frameworks (CTFs) provide opportunties in water desalination. By varying the chemical building blocks, the pore structure, chemistry, and membrane performance can be designed, leading to two orders of mangnutide higher water permeability than polyamide membranes while maintaining excellent ability to reject salts.Water scarcity is one of the most prominent challenges in modern society. 1,2 Due to the rapid growth of the world population and the accelerated industrialization of developing countries, fresh water has become increasingly scarce. Although 75% of the earth's surface is covered with water, more than 97% of it is seawater that cannot be used directly. Much of the remaining fresh water is locked in glaciers and snowfields, leaving less than 1% of the world's water available for human consumption. Despite the vast availability of seawater, the production of fresh water using processes that separate salt ions from saline water (i.e., desalination) remains negligible (less than 1%) when compared to global demand, primarily due to high costs and large energy consumption. 3 To facilitate clean water production via desalination, much recent attention has been given to improving the cost--effectiveness and energy--efficiency of reverse osmosis (RO) desalination processes, which account for roughly two thirds of installed capacity. In particular, new membranes with enhanced water permeability compared to currently available polyamide--based membranes may have an important role to play in lowering energy consumption. 4 Several nanostructured materials have been previously investigated as promising membrane candidates such as carbon nanotubes (CNTs) 5,6,7 and zeolites 8,9 . Despite CNTs' high water permeability, 5 membranes based on CNTs exhibit poor salt rejection, and it remains challenging to fabricate membranes with dense, well--aligned nanotubes. 6,7 Zeolite membranes, on the other hand, possess three--dimensional networks that can effectively reject salt ions 8 but show relatively low water permeability. 9 Recently, nanoporous one--atom--thick graphene, the thinnest possible membrane made from matter, has drawn considerable attention and been shown computationally to provide significantly enhanced permeability compared to polyamide while maintaining excellent ability to reject salt. 10 Moreover, recent work of Surwade et al. has further experimentally realized such single--layered nanoporous graphene membranes and demonstrated their potential in desalination at the lab scale. 11 However, the production of nanoporous graphene membranes with perfectly sized nanopores still remains a great challenge. Moreover, to allow unprecedentedly high water fluxes, it is of great importance to achieve a pore density as high as possible while preventing pores from overlapping, a goal best achieved with a well--ordered pore structure. Seeking membranes with naturally ordered pores of an ideal size presents an important alternative to nanoporous graphene m...

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“…Whereas some metal and complex hydrides can store large quantities of hydrogen, the extraction of the gas from the solid (reversibly) is not possible under the typical operating conditions of polymer electrolyte membrane (PEM) fuel cells; the interaction between the “host” and the chemically bound H is enthalpically too strong 2. In contrast, readily reversible materials based on physical H absorption, such as metal– organic or covalent organic frameworks (MOFs or COFs, respectively) typically exhibit low hydrogen capacities under ambient (or above ambient) temperature 3, 4. A state‐of‐the‐art framework material for hydrogen storage such as MOF 177, for instance, has a hydrogen storage capacity of 7.5 wt % at 77 K and 70 bar, whereas the storage capacity at ambient pressure is significantly lower (1 wt %) 5.…”

Section: Introductionmentioning

confidence: 99%

Facile Uptake and Release of Ammonia by Nickel Halide Ammines

et al. 2016

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Although major difficulties are experienced for hydrogen‐ storage materials to meet performance requirements for mobile applications, alternative fuel cell feedstocks such as ammonia can be stored in the solid state safely at high capacity. We herein describe the NiX2‐NH3 (X=Cl, Br, I) systems and demonstrate their exceptional suitability for NH3 storage (up to 43 wt % NH3 with desorption that begins at 400 K). The structural effects that result from the uptake of NH3 were studied by powder X‐ray diffraction (PXD), FTIR spectroscopy and SEM. NH3 release at elevated temperatures was followed by in situ PXD. The cycling capabilities and air stability of the systems were also explored. NH3 is released from the hexaammines in a three‐step process to yield the diammine, monoammine and NiX2 dihalides respectively and (re)ammoniation occurs readily at room temperature. The hexaammines do not react with air after several hours of exposure.

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Covalent organic frameworks (COFs): from design to applications

Cited by 3,325 publications

References 149 publications

Origin and Perspectives of the Photochemical Activity of Nanoporous Carbons

Origin and Perspectives of the Photochemical Activity of Nanoporous Carbons

Two-dimensional covalent triazine framework as an ultrathin-film nanoporous membrane for desalination

Facile Uptake and Release of Ammonia by Nickel Halide Ammines

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