Center for Molecular Modeling - W. Temmerman

MIL-91(Al) to Boost Solid–Solid Conversion Reactions in Li-Se Batteries

leen — Thu, 22 May 2025 08:28:22 +0000

T. Mutlu-Cetinkaya, P. Dobbelaere, W. Temmerman, W. Lu, V. Pimenta, V. Van Speybroeck, R. Demir-Cakan

Energy & Environmental Materials

8, 5

2025

Abstract

Lithium-Selenium (Li-Se) batteries have emerged as one of the most promising candidates for next-generation energy storage systems owing to superior electronic conductivity, impressive volumetric capacity, and enhanced compatibility with carbonate electrolyte of selenium, comparable to sulfur. Despite these advantages, the development of Li-Se batteries is impeded by several intrinsic challenges, including volume expansion during the discharge process and the consequent sluggish reaction kinetics that undermine their electrochemical performance. In this study, MIL-91(Al) is used as an electrode additive to accelerate the one-step mutual solid–solid conversion reaction between Se and Li₂Se in the carbonate-based electrolyte. By doing so, uncontrollable deposition of Li₂Se is effectively mitigated, enhancing the electrochemical performance of the system. Thus, the use of MIL-91(Al) results in reduced internal resistance and faster Li-ion transfer rate, as analyzed by SPEIS and GITT. Ab initio calculations and molecular dynamics simulations further reveal that Li₂Se anchors to closely situated dangling oxygens of the phosphonate group of the organic linker of MIL-91(Al), inducing relaxation of the Li-Se-Li angle and stabilizing the overall structure. Accordingly, the MIL-91(Al)-containing Li-Se cells demonstrate a high specific capacity of approximately 530 mAh g⁻¹ at 1C (675 mA g⁻¹) after 100 cycles and retaining a specific capacity of 320 mAh/g even under high current rate (20C) after 200 cycles. This research underlines the importance of the use of electrocatalyst/electroadsorbent materials to enhance the redox kinetics of the conversion reactions between Se and Li₂Se, thus paving the way for the development of high-performance Li-Se batteries.

Gold Open Access

DOI

https://doi.org/10.1002/eem2.70038

Private attachment

MIL‐91 Al to Boost Solid Solid Conversion Reactions in Li‐Se.pdf

Direct Aminolysis of Methyl Esters With Ammonia in Continuous Flow Through Bayesian Optimization

leen — Tue, 13 May 2025 09:53:17 +0000

B. Vandekerckhove, S. Desimpel, B. Ruttens, M. Bocus, W. Temmerman, B. Metten, V. Van Speybroeck, T. Heugebaert, C. Stevens

Reaction Chemistry & Engineering

10, 1887-1896

2025

Abstract

Amides play a crucial role in the pharmaceutical, animal health and agrochemical industry. Despite the availability of various catalytic systems and coupling reagents, many methods suffered from long reaction times and poor atom economy. The direct synthesis of primary amides remained particularly challenging due to the limited availability of suitable nitrogen sources. In this study, continuous flow technology was explored as a process-intensification approach for the direct amidation of methyl esters to produce primary amides. Methanolic ammonia was employed as a nitrogen source to enhance process efficiency while circumventing the limitations of aqueous ammonia and the hazards of gaseous ammonia. Seventeen substrates were screened to assess their aminolysis reactivity under these conditions. As a proof of concept, methyl picolinate was selected for continuous flow optimization using Bayesian Optimization. Therefore, a custom-designed high-pressure, high-temperature continuous flow reactor was utilized to achieve efficient, safe and scalable synthesis (200 °C, 50 bar).

DOI

https://doi.org/10.1039/D5RE00163C

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d5re00163c.pdf

Computational Modeling of Reticular Materials: The Past, the Present, and the Future

leen — Tue, 21 Jan 2025 08:23:21 +0000

W. Temmerman, R. Goeminne, K. S. Rawat, V. Van Speybroeck

Advanced Materials

2024

Abstract

Reticular materials rely on a unique building concept where inorganic and organic building units are stitched together giving access to an almost limitless number of structured ordered porous materials. Given the versatility of chemical elements, underlying nets, and topologies, reticular materials provide a unique platform to design materials for timely technological applications. Reticular materials have now found their way in important societal applications, like carbon capture to address climate change, water harvesting to extract atmospheric moisture in arid environments, and clean energy applications. Combining predictions from computational materials chemistry with advanced experimental characterization and synthesis procedures unlocks a design strategy to synthesize new materials with the desired properties and functions. Within this review, the current status of modeling reticular materials is addressed and supplemented with topical examples highlighting the necessity of advanced molecular modeling to design materials for technological applications. This review is structured as a templated molecular modeling study starting from the molecular structure of a realistic material towards the prediction of properties and functions of the materials. At the end, the authors provide their perspective on the past, present of future in modeling reticular materials and formulate open challenges to inspire future model and method developments.

DOI

https://doi.org/10.1002/adma.202412005

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Computational Modeling of Reticular Materials.pdf

A Critical Assessment on Calculating Vibrational Spectra in Nanostructured Materials

leen — Mon, 08 Jan 2024 11:24:45 +0000

A.E.J. Hoffman, W. Temmerman, E. Campbell, A. A. Damin, I. Lezcano-Gonzalez, A.M. Beale, S. Bordiga, J. Hofkens, V. Van Speybroeck

Journal of Chemical Theory and Computation

Volume: 20, Issue: 2, Pages: 513-531

2023

Abstract

Vibrational spectroscopy is an omnipresent spectroscopic technique to characterize functional nanostructured materials such as zeolites, metal–organic frameworks (MOFs), and metal–halide perovskites (MHPs). The resulting experimental spectra are usually complex, with both low-frequency framework modes and high-frequency functional group vibrations. Therefore, theoretically calculated spectra are often an essential element to elucidate the vibrational fingerprint. In principle, there are two possible approaches to calculate vibrational spectra: (i) a static approach that approximates the potential energy surface (PES) as a set of independent harmonic oscillators and (ii) a dynamic approach that explicitly samples the PES around equilibrium by integrating Newton’s equations of motions. The dynamic approach considers anharmonic and temperature effects and provides a more genuine representation of materials at true operating conditions; however, such simulations come at a substantially increased computational cost. This is certainly true when forces and energy evaluations are performed at the quantum mechanical level. Molecular dynamics (MD) techniques have become more established within the field of computational chemistry. Yet, for the prediction of infrared (IR) and Raman spectra of nanostructured materials, their usage has been less explored and remain restricted to some isolated successes. Therefore, it is currently not a priori clear which methodology should be used to accurately predict vibrational spectra for a given system. A comprehensive comparative study between various theoretical methods and experimental spectra for a broad set of nanostructured materials is so far lacking. To fill this gap, we herein present a concise overview on which methodology is suited to accurately predict vibrational spectra for a broad range of nanostructured materials and formulate a series of theoretical guidelines to this purpose. To this end, four different case studies are considered, each treating a particular material aspect, namely breathing in flexible MOFs, characterization of defects in the rigid MOF UiO-66, anharmonic vibrations in the metal–halide perovskite CsPbBr₃, and guest adsorption on the pores of the zeolite H-SSZ-13. For all four materials, in their guest- and defect-free state and at sufficiently low temperatures, both the static and dynamic approach yield qualitatively similar spectra in agreement with experimental results. When the temperature is increased, the harmonic approximation starts to fail for CsPbBr₃ due to the presence of anharmonic phonon modes. Also, the spectroscopic fingerprints of defects and guest species are insufficiently well predicted by a simple harmonic model. Both phenomena flatten the potential energy surface (PES), which facilitates the transitions between metastable states, necessitating dynamic sampling. On the basis of the four case studies treated in this Review, we can propose the following theoretical guidelines to simulate accurate vibrational spectra of functional solid-state materials: (i) For nanostructured crystalline framework materials at low temperature, insights into the lattice dynamics can be obtained using a static approach relying on a few points on the PES and an independent set of harmonic oscillators. (ii) When the material is evaluated at higher temperatures or when additional complexity enters the system, e.g., strong anharmonicity, defects, or guest species, the harmonic regime breaks down and dynamic sampling is required for a correct prediction of the phonon spectrum. These guidelines and their illustrations for prototype material classes can help experimental and theoretical researchers to enhance the knowledge obtained from a lattice dynamics study.

DOI

http://dx.doi.org/10.1021/acs.jctc.3c00942

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hoffman-et-al-2023-a-critical-assessment-on-calculating-vibrational-spectra-in-nanostructured-materials.pdf

Pushing the limits of computational chemistry: the phase diagram of water

massimo — Wed, 01 Oct 2025 07:05:26 +0000

M. Bocus, T. Braeckevelt, P. Dobbelaere, A. Maet, W. Temmerman, S. Vandenhaute, S. Vanlommel, J. Vekeman, V. Van Speybroeck

ISBN/ISSN:

Invited talk

Conference / event / venue

EuroHPC User Days 2025

Copenhagen, Denmark

Tuesday, 30 September, 2025 to Wednesday, 1 October, 2025

Direct CO2 valorization on zeolite catalysts: Identifying olefin formation pathways in a complex molecular environment

leen — Thu, 06 Feb 2025 13:02:27 +0000

W. Temmerman

Master of Science in Chemical Engineering

2023

Supervisors

Prof. Dr. ir. Veronique Van Speybroeck; Prof. Dr. ir. Pieter Cnudde

Direct CO2 valorization on zeolite catalysts: Identifying olefin formation pathways in a complex molecular environment

leen — Tue, 25 Oct 2022 12:01:45 +0000

W. Temmerman

Master of Science in Chemical Engineering

2022

Wim Temmerman

leen — Tue, 20 Sep 2022 09:12:47 +0000