Design Principles for High H₂ Storage Using Chelation of Abundant Transition Metals in Covalent Organic Frameworks for 0–700 bar at 298 K

Abstract

Physisorption is an effective route to meet hydrogen gas (H) storage and delivery requirements for transportation because it is fast and fully reversible under mild conditions. However, most current candidates have too small binding enthalpies to H which leads to volumetric capacity less than 10 g/L compared to that of the system target of 40 g/L at 298 K. Accurate quantum mechanical (QM) methods were used to determine the H binding enthalpy of 5 linkers which were chelated with 11 different transition metals (Tm), including abundant first-row Tm (Sc through Cu), totaling 60 molecular compounds with more than 4 configurations related to the different number of H that interact with the molecular compound. It was found that first-row Tm gave similar and sometimes superior van der Waals interactions with H than precious Tm. Based on these linkers, 30 new covalent organic frameworks (COFs) were constructed. The H uptakes of these new COFs were determined using quantum mechanics (QM)-based force fields and grand canonical Monte Carlo (GCMC) simulations. For the first time, the range for the adsorption pressure was explored for 0-700 bar and 298 K. It was determined that Co-, Ni-, and Fe-based COFs can give high H uptake and delivery when compared to bulk H on this unexplored range of pressure.

Rational design of functionalized covalent organic frameworks and their performance towards CO2 capture

“…Covalent organic frameworks (COFs) 1 with periodically ordered structures are a new emerging type of porous crystalline material, and have gained great attention in recent years. [2][3][4] Owing to their features of robust framework, inherent porosity and tailormade functionalities, COFs have recently been seen as a new porous platform for extensive applications such as gas storage and separation, [5][6][7] optoelectronics, [8][9][10] catalysis, [11][12][13] and chemical sensor. [14][15][16] Thus far, in order to achieve excellent performance, a pore channel post-modication strategy has been seen as an effective means of introducing various functional moieties to modify the surface properties of the COF skeleton.…”

Fe-doped H3PMo12O40 immobilized on covalent organic frameworks (Fe/PMA@COFs): a heterogeneous catalyst for the epoxidation of cyclooctene with H2O2

“…Covalent organic frameworks (COFs) are a class of crystalline organic porous materials that are constructed from light elements and linked by covalent bonds to create predesigned skeletons and nanopores. 1,2 By means of the organic functional group of the framework, a multitude of active sites are introduced into the porous network to develop COFs with diverse applications, such as gas storage and separation, [3][4][5][6] energy conversion, 7 optoelectronics, [8][9][10] and catalysis. [11][12][13][14] According to research, imine-based COFs are highly stable in water and common organic solvents; moreover, coordination chemistry demonstrates that imine-type ligands are versatile in incorporating a variety of metal ions.…”

Three dimensional nanoscale analysis reveals aperiodic mesopores in a covalent organic framework and conjugated microporous polymer

“…The structural characterisation of low-crystalline, disordered or aperiodic solids remains one of the biggest challenges faced by the chemistry community, 1 but it is vitally important for harnessing the properties of many enigmatic disordered molecular materials. 2 New types of porous materials, such as covalent organic frameworks (COFs) 3 and conjugated microporous polymers (CMPs) 4 attract much interest as synthetic organic 2D materials, that offer many functional properties that could be exploited for uses in gas storage, 5 sensing, 6,7 drug delivery 8,9 or catalysis, 10,11 in addition to a microporous structure allowing for the tuning of their electronic bandgap. 12,13 However, the complex and often disordered 3D structures of CMPs and COFs to some extent present a significant hurdle for establishing structure-property relations and thus hinder the development of practical applications for these innovative materials.…”