arXiv subjects

Joshua Edzards

Publications and source records attributed to Joshua Edzards.

7 recordsLinked to original sources

arXiv2026

Linker Functionalization and pH Tuning Enhance Solar-Driven Catalytic CO$_2$ Reduction in MOF-5

The wide band gap of metal-organic framework (MOF) 5 constrains its use in photocatalytic carbon dioxide (CO$_2$) reduction despite its high porosity and favorable mass-transport properties. Adopting a state-of-the-art first-principles approach, we systematically investigate the effects of volumetric strain, metal-node substitution, linker functionalization, and pH control as knobs to improve the CO$_2$ photocatalytic ability of MOF-5. Strain and metal-node substitution negligibly affect the gap, whereas linker functionalization narrows it into the visible range via in-gap states while preserving reduction-side alignment at pH = 0. The resulting reduction energetics are strongly sensitive to both linker functionalization and pH. Halogenated and hydroxylated frameworks provide access primarily to HCOOH, CO, and HCHO under alkaline conditions, principally with the Mg and Zn nodes, whereas COOH functionalization offers the broadest thermodynamic accessibility across the full CO$_2$ reduction sequence. NH$_2$ retains thermodynamic feasibility for all target reduction pathways but with larger overpotentials, while NO$_2$ generally yields unfavorable reduction energetics. Crucially, within the COOH series, the choice of the metal node tunes the fundamental gap by over 1 eV with only minor changes in the reduction overpotentials, placing Sr- and Ba-based architectures as the most favorable ones for broad product selectivity with visible-light excitation. Linker functionalization substantially reduces the spatial overlap of the frontier states, promoting photoinduced charge separation. Taken together, these results establish linker functionalization and solution pH as complementary design levers for independently tuning light absorption and CO$_2$-reduction energetics in MOF-5, establishing a rational and viable route for designing efficient MOF-based photocatalysts.

cond-mat.mtrl-sci↗

arXiv2026

Enhancing Hydrogen Adsorption Ability of MOF-5 with Metal Node Exchange and Linker Functionalisation

In the search for promising material candidates for hydrogen storage, we investigate from first principles derivatives of metal organic framework 5 (MOF-5), including isoelectronic substitution of the metal centers (Zn $\rightarrow$ Mg, Cd) and linker functionalization with NH$_2$, OH, and NO$_2$ groups. Metal-node substitution consistently stabilises and ligand functionalization systematically enhances H$_2$ binding at the metal-oxo cluster sites. The combination of Cd centers and NO$_2$ groups proves to be most efficient, yielding an adsorption energy of -15.58 kJ mol$^{\text{-1}}$, which substantially outperforms the storage ability of pristine MOF-5. Detailed electronic structure analysis clarifies how the local framework environment coordinates the guest molecule, providing a robust design framework to guide the experimental development of advanced adsorbent materials.

cond-mat.mtrl-sci↗

arXiv2026

AIM2DAT: A Python-based Automated Ab Initio Material Modeling and Data Analysis Toolkit

The emergence of data-driven computational materials science offers unprecedented opportunities to explore complex material landscapes, complementing experimental research with the discovery of novel compounds. To enable these developments, it is essential to establish robust, reliable, and easy-to-use software supporting workflow automation and large dataset processing. Herein, we introduce the Automated Ab Initio Materials Modeling and Data Analysis Toolkit (aim2dat), a Python package offering a user-friendly interface to generate and handle big data, design high-throughput workflows based on density functional theory calculations, and analyze the output. Its key features include interfaces to online databases for structure query and analysis, high-throughput screening routines, and seamless integration of machine learning models. The capabilities of aim2dat are showcased with a variety of use-cases, ranging from photocathode materials to metal-organic frameworks.

cond-mat.mtrl-sci↗

arXiv2025

Benchmarking Selected Density Functionals and Dispersion Corrections for MOF-5 and its Derivatives

Accurate computational predictions of metal-organic frameworks (MOFs) and their properties is crucial for discovering optimal compositions and applying them in relevant technological areas. This work benchmarks density functional theory (DFT) approaches, including semi-local, meta-GGA, and hybrid functionals with various dispersion corrections, on MOF-5 and three of its computationally predicted derivatives, analyzing structural, electronic, and vibrational properties. Our results underline the importance of explicitly treating van der Waals interactions for an accurate description of structural and vibrational properties, and indicate the meta-GGA functional R2SCAN as the best balance between accuracy and efficiency for characterizing the electronic structure of these systems, in view of future high-throughput screening studies on MOFs.

cond-mat.mtrl-sci↗

arXiv2024

Tuning Structural and Electronic Properties of Metal-Organic Framework 5 by Metal Substitution and Linker Functionalization

The chemical flexibility of metal-organic frameworks (MOFs) offers an ideal platform to tune structure and composition for specific applications, from gas sensing to catalysis and from photoelectric conversion to energy storage. This variability gives rise to a large configurational space that can be efficiently explored using high-throughput computational methods. In this work, we investigate from first principles the structural and electronic properties of MOF-5 variants obtained by replacing Zn with Be, Mg, Cd, Ca, Sr, and Ba, and by functionalizing the originally H-passivated linkers with CH$_3$, NO$_2$, Cl, Br, NH$_2$, OH, and COOH groups. To build and analyze the resulting 56 structures, we employ density-functional theory calculations embedded in an in-house developed library for automatized calculations. Our findings reveal that structural properties are mainly defined by metal atoms and large functional groups which distort the lattice and modify coordination. Stability is largely influenced by functionalization and enhanced by COOH and OH groups which promote the formation of hydrogen bonds. The charge distribution within the linker is especially influenced by functional groups with electron-withdrawing character while the metal nodes play a minor role. Likewise, the band-gap size is crucially determined by ligand functionalization. The smallest gaps are found with NH$_2$ and OH groups which introduce localized orbitals at the top of the valence band. This characteristic makes these functionalizations particularly promising for the design of MOF-5 variants with enhanced gas uptake and sensing properties.

cond-mat.mtrl-sci↗

arXiv2023

Impact of Ligand Substitution and Metal Node Exchange in the Electronic Properties of Scandium Terephthalate Frameworks

The search for sustainable alternatives to established materials is a sensitive topic in materials science. Due to their unique structural and physical characteristics, the composition of metal-organic frameworks (MOFs) can be tuned by the exchange of the metal nodes and the functionalization of the organic ligands giving rise to a large configurational space. Considering the case of scandium terephthalate MOFs and adopting an automatized computational framework based on density-functional theory, we explore the impact of metal substitution with the earth-abundant isoelectronic elements Al and Y, and of ligand functionalization of varying electronegativity. We find that structural properties are strongly impacted by the metal ion substitution and only moderately by ligand functionalization. In contrast, the energetic stability, the charge density distribution, and the electronic properties - including the size of the band gap - are primarily affected by the termination of the linker molecules. Functional groups such as OH and NH$_2$ lead to particularly stable structures thanks to the formation of hydrogen bonds and affect the electronic structure of the MOFs by introducing mid-gap states.

cond-mat.mtrl-sci↗

arXiv2023

The Effects of Ligand Substituents on the Character of Zn-Coordination in Zeolitic Imidazolate Frameworks

Due to their favorable properties and high porosity, zeolitic imidazolate frameworks (ZIFs) have recently received much limelight for key technologies such as energy storage, optoelectronics, sensorics, and catalysis. Despite the widespread interest in these materials, fundamental questions regarding the zinc coordination environment remain poorly understood. By focusing on zinc(II)2-methylimidazolate (ZIF-8) and its tetrahedrally coordinated analogs with Br-, Cl-, and H-substitution in the 2-ring position, we aim to clarify how variations in the local environment of Zn impact the charge distribution and the electronic properties of these materials. Our results from density-functional theory confirm the presence of a Zn coordinative bond with a large polarization that is quantitatively affected by different substituents on the organic ligand. Moreover, our findings suggest that the variations induced by the functionalization in the Zn coordination have a negligible effect on the electronic structure of the considered compounds. On the other hand, halogen terminations of the ligands lead to distinct electronic contributions in the vicinity of the frontier region which ultimately reduce the band-gap size by a few hundred meV. Experimental results obtained from X-ray absorption spectroscopy (Zn $K$-edge) confirm the trends predicted by theory and, together with them, contribute to a better understanding of the structure-property relationships that are needed to tailor ZIFs for target applications.

cond-mat.mtrl-sci↗