Acid Gas Adsorption on Metal–Organic Framework Nanosheets as a Model of an “All-Surface” Material

Abstract

To establish a model of metal-organic framework (MOF) surfaces and build an understanding of surface-specific ligand adsorption phenomena in MOFs, we present a computational study exploring multiple models of a series of MOF-2 nanosheet materials, "M-BDCs", with M = Zn, Cu, and Co and BDC = benzene-1,4-dicarboxylate. We study and assess the appropriateness of a series of models ranging from small clusters (18 atoms) to fully periodic sheet models. We additionally study the interactions of these models with acid gases and energy-relevant small molecules (CO, CO, HO, SO, NO, and HS). We employ computational methods ranging from DFT with various exchange-correlation functionals to perturbative and coupled-cluster methods. For these systems, we present binding energies and enthalpies with the various ligands studied as well as IR frequency shifts for the normal modes of these ligands upon complexation with the open-metal sites of these materials. Our calculations lead to an understanding of phenomena unique to MOF surfaces and the importance of the periodicity in these materials in capturing surface-specific adsorption behaviors.

Structural Engineering of Low‐Dimensional Metal–Organic Frameworks: Synthesis, Properties, and Applications

“…MOF‐based materials with high surface area, large void spaces and controllable surface properties have attracted much attention in the field of gas adsorption and separation, such as CO 2 capture, H 2 and CH 4 purifications, and CH 4 storage . Previous researches have demonstrated that LD MOFs with high aspect ratio and unique physicochemical properties possess superior sorption behaviors over their bulk counterparts . For instance, Marmottini and co‐workers have reported a 1D phosphinate‐based MOF rods for CO 2 uptake .…”

“…[48][49][50] These types of MOFs, such as 1D single-walled MOF nanotubes, 1D hexagonal MOF nanorods, ultrathin 2D MOF nanosheets, [51][52][53] have similar morphological features to those of the other 1D or 2D nanomaterials, which endows them with distinctive dimensional-dependent properties including high aspect ratio and abundant accessible active sites. [60][61][62][63][64][65][66][67][68][69][70][71][72][73][74][75] Although the advantages and challenges of 1D metal-organic nanotubes [76] and 2D MOF nanosheets [48,50,56] have been well summarized by several previous review articles, the research field of LD MOFs is currently at a stage of rapid development, as indicated by annually increased amount of publications (Figure 2). To achieve effective and controllable preparation of LD MOFs, a large number of synthetic methods have been developed, such as template method, ultrasonic exfoliation, surfactant-assisted growth, three-layer method, etc.…”

“…Additionally, various LD MOF‐based composites and their derived hybrid nanomaterials with multifunctions have also been successfully prepared in recent years . Owing to their unique structures, LD MOFs are promising for a variety of applications, including gas adsorption and separation, heterogeneous catalysis, energy storage and conversion, and so on ( Figure ) . Although the advantages and challenges of 1D metal‐organic nanotubes and 2D MOF nanosheets have been well summarized by several previous review articles, the research field of LD MOFs is currently at a stage of rapid development, as indicated by annually increased amount of publications ( Figure ).…”

Interactions of CO2 with cluster models of metal–organic frameworks

“…[33] Taking a different approach, Howe et al looked at the interactions of several gases with the external surfaces of MOFs. [34] Their calculations utilized a number of density functionals and wavefunction and gas molecules. [35] Their methodology uses a decomposition of second-order Møller-Plesset perturbation theory interactions as the basis for the terms of a new force field.…”

A DFT Screening of M-HKUST-1 MOFs for Nitrogen-Containing Compounds Adsorption

“…Despite the extensive experimental studies on the adsorption performance of NCCs on HKUST-1, only a few theoretical researches have focused on NCCs’ adsorption behavior in MOFs. A lot of theoretical work has studied the adsorption in various MOFs of small molecules such as CO 2 [ 20 , 21 , 22 ], SO 2 [ 23 , 24 ], dibenzothiophene [ 25 ], CH 4 [ 21 , 26 , 27 ], N 2 [ 21 ], N 2 O [ 28 ], H 2 [ 21 ], and noble gas [ 29 ]. To our best knowledge, a systematic study on the adsorption of three NCCs (NO, NO 2 , and NH 3 ) on 19 metal-substituted variants of HKUST-1 is still missing.…”