S.M.J. Rogge

Water motifs in zirconium metal-organic frameworks induced by nanoconfinement and hydrophilic adsorption sites

A. Lamaire, J. Wieme, S. Vandenhaute, R. Goeminne, S.M.J. Rogge, V. Van Speybroeck
Nature Communications
15, 9997
2024
A1

Abstract 

The intricate hydrogen-bonded network of water gives rise to various structures with anomalous properties at different thermodynamic conditions. Nanoconfinement can further modify the water structure and properties, and induce specific water motifs, which are instrumental for technological applications such as atmospheric water harvesting. However, so far, a causal relationship between nanoconfinement and the presence of specific hydrophilic adsorption sites is lacking, hampering the further design of nanostructured materials for water templating. Therefore, this work investigates the organisation of water in zirconium-based metal-organic frameworks (MOFs) with varying topologies, pore sizes, and chemical composition, to extract design rules to shape water. The highly tuneable pores and hydrophilicity of MOFs makes them ideally suited for this purpose. We find that small nanopores favour orderly water clusters that nucleate at hydrophilic adsorption sites. Favourably positioning the secondary adsorption sites, hydrogen-bonded to the primary adsorption sites, allows larger clusters to form at moderate adsorption conditions. To disentangle the importance of nanoconfinement and hydrophilic nucleation sites in this process, we introduce an analytical model with precise control of the adsorption sites. This sheds a new light on design parameters to induce specific water clusters and hydrogen-bonded networks, thus rationalising the application space of water in nanoconfinement.

Gold Open Access

DOI 

http://dx.doi.org/10.1038/s41467-024-54358-z

High-Throughput Screening of Covalent Organic Frameworks for Carbon Capture Using Machine Learning

J. De Vos, S. Ravichandran, S. Borgmans, L. Vanduyfhuys, P. Van der Voort, S.M.J. Rogge, V. Van Speybroeck
Chemistry of Materials
36, 9, 4315-4330
2024
A1

Abstract 

Postcombustion carbon capture provides a high-potential pathway to reduce anthropogenic CO2 emissions in the short term. In this respect, nanoporous materials, such as covalent organic frameworks (COFs), offer a promising platform as adsorbent beds. However, due to the modular nature of COFs, an almost unlimited number of structures can possibly be synthesized. To efficiently identify promising materials and reveal performance trends within the COF material space, we present a computational high-throughput screening of 268,687 COFs for their ability to efficiently and selectively separate CO2 from the flue gas of power plants using a pressure swing adsorption process. Furthermore, we demonstrate that our screening can be significantly accelerated using machine learning to identify a set of promising materials. These are subsequently characterized with high accuracy, taking into account the effects of competitive adsorption and coadsorption. Our screening reveals that imide, (keto)enamine, and (acyl)hydrazone COFs are particularly interesting for carbon capture. Additionally, the best-performing materials are 3D COFs possessing strong CO2 adsorption sites between aromatic rings at opposite sides of pores with a diameter of 1.0 nm. In 2D COFs, a significant influence of the framework chemistry, such as imide linkages or fluoro groups, is observed. Our design rules can guide experimental researchers to construct high-performing COFs for CO2 capture.

Gold Open Access

DOI 

http://dx.doi.org/10.1021/acs.chemmater.3c03230

Additivity of atomic strain fields as a tool to strain-engineering phase-stabilized CsPbI3 perovskites

J. Teunissen, T. Braeckevelt, I. Skvortsova, J. Guo, B. Pradhan, E. Debroye, M. Roeffaers, J. Hofkens, S. Van Aert, S. Bals, S.M.J. Rogge, V. Van Speybroeck
The Journal of Physical Chemistry C
127, 48, 23400-23411
2023
A1

Abstract 

CsPbI3 is a promising perovskite material for photovoltaic applications in its photoactive perovskite or black phase. However, the material degrades to a photovoltaically inactive or yellow phase at room temperature. Various mitigation strategies are currently being developed to increase the lifetime of the black phase, many of which rely on inducing strains in the material that hinder the black-to-yellow phase transition. Physical insight into how these strategies exactly induce strain as well as knowledge of the spatial extent over which these strains impact the material is crucial to optimize these approaches but is still lacking. Herein, we combine machine learning potential-based molecular dynamics simulations with our in silico strain engineering approach to accurately quantify strained large-scale atomic structures on a nanosecond time scale. To this end, we first model the strain fields introduced by atomic substitutions as they form the most elementary strain sources. We demonstrate that the magnitude of the induced strain fields decays exponentially with the distance from the strain source, following a decay rate that is largely independent of the specific substitution. Second, we show that the total strain field induced by multiple strain sources can be predicted to an excellent approximation by summing the strain fields of each individual source. Finally, through a case study, we illustrate how this additive character allows us to explain how complex strain fields, induced by spatially extended strain sources, can be predicted by adequately combining the strain fields caused by local strain sources. Hence, the strain additivity proposed here can be adopted to further our insight into the complex strain behavior in perovskites and to design strain from the atomic level onward to enhance their sought-after phase stability.

Open Access version available at UGent repository
Gold Open Access

DOI 

http://dx.doi.org/10.1021/acs.jpcc.3c05770

OGRe: Optimal grid refinement protocol for accurate free energy surfaces and its application to proton hopping in zeolites and 2D COF stacking

S. Borgmans, S.M.J. Rogge, L. Vanduyfhuys, V. Van Speybroeck
Journal of Chemical Theory and Computation
19, 24, 9032-9048
2024
A1

Abstract 

While free energy surfaces are the crux of our understanding in many chemical and biological processes, their accuracy is generally unknown. Moreover, many developments to improve their accuracy are often complicated, impeding their general use. Luckily, several tools and guidelines are already in place to identify these shortcomings, but they are typically lacking in flexibility or fail to systematically determine how to improve the accuracy of the free energy calculation. To overcome these limitations, this work introduces OGRe--a python package for optimal grid refinement in an arbitrary number of dimensions. OGRe is based on three metrics which gauge the confinement, consistency, and overlap of each simulation in a series of umbrella sampling (US) simulations, an enhanced sampling technique ubiquitously adopted to construct free energy surfaces for hindered processes. As these three metrics are fundamentally linked to the accuracy of the weighted histogram analysis method, adopted to generate free energy surfaces from US simulations, they facilitate a systematic construction of accurate free energy profiles, where each metric is driven by a specific umbrella parameter. This allows for the derivation of a consistent and optimal collection of umbrellas for each simulation, largely independent of the initial values, thereby dramatically increasing the ease-of-use towards accurate free energy surfaces. As such, OGRe is particularly suited to determined complex free energy surfaces, with large activation barriers and shallow minima, which underpin many physical and chemical transformations, and hence to further our fundamental understanding of these processes.

Gold Open Access

DOI 

https://doi.org/10.1021/acs.jctc.3c01028

Quantum tunneling rotor as a sensitive atomistic probe of guests in a metal-organic framework

K. Titov, M.R. Ryder, A. Lamaire, Z. Zeng, A.K. Chaudhari, J. Taylor, E.M. Mahdi, S.M.J. Rogge, S. Mukhopadhyay, S. Rudić, V. Van Speybroeck, F. Fernandez-Alonso, J.-C. Tan
Physical Review Materials
7, 073402
2023
A1

Abstract 

Quantum tunneling rotors in a zeolitic imidazolate framework ZIF-8 can provide insights into local gas adsorption sites and local dynamics of porous structure, which are inaccessible to standard physisorption or x-ray diffraction sensitive primarily to long-range order. Using in situ high-resolution inelastic neutron scattering at 3 K, we follow the evolution of methyl tunneling with respect to the number of dosed gas molecules. While nitrogen adsorption decreases the energy of the tunneling peak, and ultimately hinders it completely (0.33 meV to zero), argon substantially increases the energy to 0.42 meV. Ab initio calculations of the rotational barrier of ZIF-8 show an exception to the reported adsorption sites hierarchy, resulting in anomalous adsorption behavior and linker dynamics at subatmospheric pressure. The findings reveal quantum tunneling rotors in metal-organic frameworks as a sensitive atomistic probe of local physicochemical phenomena.

Gold Open Access

DOI 

http://dx.doi.org/10.1103/PhysRevMaterials.7.073402

MOFs for long-term gas storage: Exploiting kinetic trapping in ZIF-8 for on-demand and stimuli-controlled gas release

K. Heinz, S.M.J. Rogge, A. Kalytta-Mewes, D. Volkmer, H. Bunzen
Inorganic Chemistry Frontiers
10, 16, 4763-4772
2023
A1

Abstract 

In this study, we investigate the potential of metal–organic frameworks (MOFs) for long-term gas storage under ambient conditions. Specifically, we selected a MOF ZIF-8 (with a 0.34 nm large pore aperture), which exhibits a temperature- and pressure-regulated gating effect, and loaded it with sulphur hexafluoride (with a kinetic diameter of 0.55 nm). By optimising the loading conditions, we were able to achieve up to 33 wt% SF6 loading into the pores of ZIF-8. Although MOFs featuring gating effects are known to adsorb gases larger than the pore openings, herein, by applying high pressure (and optionally elevated temperature), kinetic trapping of the gas guest was also achieved. When investigating the gas release under ambient conditions, three MOF samples of different crystal sizes (ca. 45 nm, 1.5 μm and 5 μm) were examined. Remarkably, for the largest crystals, more than 86% of the initially loaded gas remained trapped in the pores even after being exposed to air for 100 days under ambient conditions. Our findings indicate that the extremely slow release of SF6 is due to the high activation energy for the guest diffusion through the narrow pore opening in ZIF-8, which was supported by both ab initio-based computational studies and experimental data including modulated thermogravimetric analysis. On the other hand, we also showed that the gas could be released on-demand by applying an elevated temperature or by exposing the MOF to an acidic environment, which opens possibilities for facile gas micro- and nano-dosing applications.

 

DOI 

http://dx.doi.org/10.1039/D3QI01007D

ReDD-COFFEE: A ready-to-use database of covalent organic framework structures and accurate force fields to enable high-throughput screenings

J. De Vos, S. Borgmans, P. Van der Voort, S.M.J. Rogge, V. Van Speybroeck
J. Mater. Chem. A
11, 14, 7468-7487
2023
A1

Abstract 

Covalent organic frameworks (COFs) are a versatile class of building block materials with outstanding properties thanks to their strong covalent bonds and low density. Given the sheer number of hypothetical COFs envisioned via reticular synthesis, only a fraction of all COFs have been synthesized so far. Computational high-throughput screenings offer a valuable alternative to speed-up such materials discovery. Yet, such screenings vitally depend on the availability of diverse databases and accurate interatomic potentials to efficiently predict each hypothetical COF’s macroscopic behavior, which is currently lacking. Therefore, we herein present ReDD-COFFEE, the Ready-to-use and Diverse Database of Covalent Organic Frameworks with Force field based Energy Evaluation, containing 268 687 COFs and accompanying ab initio derived force fields that are shown to outperform generic ones. Our structure assembly approach results in a huge amount of computer-ready structures with a high diversity in terms of geometric properties, linker cores, and linkage types. Furthermore, the textural properties of the database are analyzed and the most promising COFs for vehicular methane storage are identified. By making the database freely accessible, we hope it may also inspire others to further explore the potential of these intriguing functional materials.

 

Gold Open Access

DOI 

http://dx.doi.org/10.1039/D3TA00470H

MicMec: Developing the Micromechanical Model to Investigate the Mechanics of Correlated Node Defects in UiO-66

J. Vandewalle, J. De Vos, S.M.J. Rogge
J. Phys. Chem. C
127, 12, 6060-6070
2023
A1

Abstract 

New functional materials, such as mixed matrix membranes and metal–organic framework (MOF) monoliths, outperform traditional materials in gas separation and storage applications, among other pressing challenges. However, while most engineered materials nowadays exhibit spatial heterogeneities on different length scales, available simulation techniques to date cannot capture this spatial complexity fully. Herein, we present the MicMec implementation of the micromechanical model we introduced earlier as a systematic coarse-graining approach to routinely access these larger length scales and characterize the mechanical properties of these materials. We thoroughly discuss the key components of our open-source code and validate it both on an analytical system and a case study on correlated reo defects in the UiO-66 MOF. We reveal that the time step that can be reached in micromechanical simulations is 2 to 3 orders of magnitude larger than for atomistic simulations, while still capturing well the macroscopic mechanical properties of the spatially disordered UiO-66 material. It is our hope that the MicMec implementation discussed here may provide a complementary tool to existing atomistic and coarse-grained software and aid the computational design of new materials for pressing applications.

Gold Open Access

DOI 

http://dx.doi.org/10.1021/acs.jpcc.3c00451

Microscopic Linker Distribution in Mixed-Linker Zeolitic Imidazolate Frameworks via Computational Raman Spectroscopy: Implications for Gas Separation

A.E.J. Hoffman, J. Marreiros, S.M.J. Rogge, R. Ameloot, V. Van Speybroeck
ACS Applied Nano Materials
6, 7, 5645–5652
2023
A1

Abstract 

Mixed-linker zeolitic imidazolate frameworks (ZIFs) are important candidate materials for gas separation. By changing the linker content, their pore size can be tuned, offering the potential to regulate diffusion and adsorption. An important factor affecting these properties in mixed-linker ZIFs is the linker distribution, which is difficult to characterize. In this study, the microscopic linker distribution in mixed-linker ZIF-8/ZIF-90, with respectively methyl and carboxaldehyde functionalization, is elucidated via computational Raman spectroscopy. It is shown that the typical Raman band associated with the carboxaldehyde linker is shifted due to a change in hydrogen-bonding behavior. This insight allows one to explain the microscopic linker distribution in experimental mixed-linker structures.

DOI 

http://dx.doi.org/10.1021/acsanm.3c00106

Absorbing stress via molecular crumple zones: Strain engineering flexibility into the rigid UiO-66 material

S.M.J. Rogge, S. Borgmans, V. Van Speybroeck
Matter
6, 5, 1435-1462
2023
A1

Abstract 

Nanostructured materials such as metal-organic frameworks and perovskites can be tuned toward applications ranging from sensors to photovoltaic devices. Such design requires causal relations between a material’s atomic structure and macroscopic function, which remain elusive. Therefore, we herein introduce strain engineering as a general approach to rationalizing and designing how atomic-level structural modifications induce dynamically interacting strain fields that dictate a material’s macroscopic mechanical behavior. We first demonstrate the potential of strain engineering by designing shear instabilities in UiO-66, leading to counterintuitive behavior. The strain-engineered structures exhibit time- and space-dependent crumple zones that instill flexibility in the rigid material and locally focus the strain, partially preserving the material’s porosity under compression. Secondly, our strain fields help explain stimulus-induced phase coexistence in the flexible CoBDP, DMOF-1(Zn), and MIL-53(Al)-F materials. These examples demonstrate how strain engineering can be adopted to design state-of-the-art materials for challenging applications from the atomic level onward.

 

Gold Open Access

DOI 

http://dx.doi.org/10.1016/j.matt.2023.02.009

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