Trapping gases in metal-organic frameworks with a selective surface molecular barrier layer

Abstract

The main challenge for gas storage and separation in nanoporous materials is that many molecules of interest adsorb too weakly to be effectively retained. Instead of synthetically modifying the internal surface structure of the entire bulk—as is typically done to enhance adsorption—here we show that post exposure of a prototypical porous metal-organic framework to ethylenediamine can effectively retain a variety of weakly adsorbing molecules (for example, CO, CO2, SO2, C2H4, NO) inside the materials by forming a monolayer-thick cap at the external surface of microcrystals. Furthermore, this capping mechanism, based on hydrogen bonding as explained by ab initio modelling, opens the door for potential selectivity. For example, water molecules are shown to disrupt the hydrogen-bonded amine network and diffuse through the cap without hindrance and fully displace/release the retained small molecules out of the metal-organic framework at room temperature. These findings may provide alternative strategies for gas storage, delivery and separation.

High stability of ultra-small and isolated gold nanoparticles in metal–organic framework materials

“…In addition to our TEM and BET analyses, which already suggest that the Au NPs are located inside the MOF, we also use Low Energy Ion scattering (LEIS), 75 which is a more precise technique to validate this conclusion. 50 Au is localized below the surface of the as-prepared MOF crystals, as Au particles present at the surface would produce a clear surface peak in the spectra.…”

High-throughput screening of metal–organic frameworks for kinetic separation of propane and propene

“…For this purpose we use the nudged elastic band (NEB) method 35,36 that is often used to calculate ion mobility in solids but has also been applied to study molecular diffusion. 42,43 Since the NEB method can calculate the barrier energy using either a force field or a DFT approach this will allow us to make a direct comparison between the UFF-FM and DFT data. The automatic generation of the NEB setup that involves the identification of a local minimum at each side of the pore window and the construction of the path between these two end points is one of the challenges we tackle in this paper.…”

MOF derived carbon based nanocomposite materials as efficient electrocatalysts for oxygen reduction and oxygen and hydrogen evolution reactions

“…Traditionally, MOFs have found application in gas separation, storage and capture of specic molecules. [80][81][82][83][84][85] They have also been utilized for catalysis, sensing and for various optoelectronic applications. [85][86][87][88][89][90] Of late, MOFs and their derivatives have been explored as electrocatalysts.…”