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The facet-dependent adsorption of CO on oxidized and reduced CeO2 single crystal surfaces is reviewed, with emphasis on the effect of CO coverage and the ability of state-of-the-art quantum-mechanical methods to provide reliable energies and an accurate description of the IR vibrational frequency of CO. Comparison with detailed, high-resolution experimental infrared reflection absorption spectroscopy data obtained for single crystal samples allows the assignment of the different CO vibrational bands observed on all three low-index ceria surfaces. Good agreement is achieved with the hybrid density functional theory approach with the HSE06 functional and with saturation coverage. It is shown that CO is very sensitive to the structure of cerium oxide surfaces and to the presence of oxygen vacancies. The combined theoretical-experimental approach offers new opportunities for a better characterization of ceria nanoparticles and for unraveling changes occurring during reactions involving CO at higher pressures. [ABSTRACT FROM AUTHOR]

CeO2‐supported noble metal clusters are attractive catalytic materials for several applications. However, their atomic dispersion under oxidizing reaction conditions often leads to catalyst deactivation. In this study, the noble metal cluster formation threshold is rationally adjusted by using a mixed CeO2‐Al2O3 support. The preferential location of Pd on CeO2 islands leads to a high local surface noble metal concentration and promotes the in situ formation of small Pd clusters at a rather low noble metal loading (0.5 wt %), which are shown to be the active species for CO conversion at low temperatures. As elucidated by complementary in situ/operando techniques, the spatial separation of CeO2 islands on Al2O3 confines the mobility of Pd, preventing the full redispersion or the formation of larger noble metal particles and maintaining a high CO oxidation activity at low temperatures. In a broader perspective, this approach to more efficiently use the noble metal can be transferred to further systems and reactions in heterogeneous catalysis. [ABSTRACT FROM AUTHOR]

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Thin films of crystalline solids with substantial free volume built from organic chromophores and metal secondary building units (SBUs) are promising for engineering new optoelectronic properties through control of interchromophore coupling. Zn‐based SBUs are especially relevant in this case because they avoid quenching the chromophore's luminescence. We find that layer‐by‐layer spin‐coating using Zn acetate dihydrate and benzene‐1,4‐dicarboxylic acid (H2BDC) and biphenyl‐4,4'‐dicarboxylic acid (H2BPDC) linkers readily produces crystalline thin films. However, analysis of the grazing‐incidence wide‐angle X‐ray scattering (GIWAXS) data reveals the structures of these films vary significantly with the linker, and with the metal‐to‐linker molar ratio used for fabrication. Under equimolar conditions, H2BPDC creates a type of structure like that proposed for SURMOF‐2, whereas H2BDC generates a different metal‐hydroxide‐organic framework. Large excess of Zn2+ ions causes the growth of layered zinc hydroxides, irrespective of the linker used. Density functional theory (DFT) calculations provide structural models with minimum total energy that are consistent with the experimentally observed diffractograms. In the broader sense, this work illustrates the importance in this field of careful structure determination, e. g., by utilizing GIWAXS and DFT simulations to determine the structure of the obtained crystalline metal‐organic thin films, such that properties can be rationally engineered and explained. [ABSTRACT FROM AUTHOR]

The surface structure and chemical properties of Y‐stabilized zirconia (YSZ) have been subjects of intense debate over the past three decades. However, a thorough understanding of chemical processes occurring at YSZ powders faces significant challenges due to the absence of reliable reference data acquired for well‐controlled model systems. Here, we present results from polarization‐resolved infrared reflection absorption spectroscopy (IRRAS) obtained for differently oriented, Y‐doped ZrO2 single‐crystal surfaces after exposure to CO and D2O. The IRRAS data reveal that the polar YSZ(100) surface undergoes reconstruction, characterized by an unusual, red‐shifted CO band at 2132 cm−1. Density functional theory calculations allowed to relate this unexpected observation to under‐coordinated Zr4+ cations in the vicinity of doping‐induced O vacancies. This reconstruction leads to a strongly increased chemical reactivity and water spontaneously dissociates on YSZ(100). The latter, which is an important requirement for catalysing the water‐gas‐shift (WGS) reaction, is absent for YSZ(111), where only associative adsorption was observed. Together with a novel analysis Scheme these reference data allowed for an operando characterisation of YSZ powders using DRIFTS (diffuse reflectance infrared Fourier transform spectroscopy). These findings facilitate rational design and tuning of YSZ‐based powder materials for catalytic applications, in particular CO oxidation and the WGS reaction. [ABSTRACT FROM AUTHOR]

We investigate the electronic and vibrational properties of bottom-up synthesized aligned armchair graphene nanoribbons of N = 7 carbon atoms width periodically doped by substitutional boron atoms (B-7AGNRs). Using angle-resolved photoemission spectroscopy and density functional theory calculations, we find that the dopant-derived valence and conduction band states are notably hybridized with electronic states of Au substrate and spread in energy. The interaction with the substrate leaves the bands with pure carbon character rather unperturbed. This results in an identical effective mass of ≈0.2 m0 for the next-highest valence band compared with pristine 7AGNRs. We probe the phonons of B-7AGNRs by ultrahigh-vacuum (UHV) Raman spectroscopy and reveal the existence of characteristic splitting and red shifts in Raman modes due to the presence of substitutional boron atoms. Comparing the Raman spectra for three visible lasers (red, green, and blue), we find that interaction with gold suppresses the Raman signal from B-7AGNRs and the energy of the green laser (2.33 eV) is closer to the resonant E22 transition. The hybridized electronic structure of the B-7AGNR-Au interface is expected to improve electrical characteristics of contacts between graphene nanoribbon and Au. The Raman fingerprint allows the easy identification of B-7AGNRs, which is particularly useful for device fabrication.

The basic modules for materials research are systems for the design, synthesis, preparation, analysis, and application of materials and materials systems. To be efficient and produce findable, accessible, interoperable, and reusable (FAIR) data, state‐of‐the‐art materials research needs to consider the integration of research data management (RDM) workflows and, in the end, the implementation of process automation concepts for all parts of the main modules. Here, the state‐of‐the‐art methods of RDM in academia are described and a perspective on the future of digitalized molecular material systems workflows is given. The different elements of an integrated research data management strategy are described, and examples of automated processes are depicted. As such, the use of electronic lab notebooks for comprehensive documentation, the use of data‐integration and data‐conversion strategies, and the establishment of two platforms that enable the automated synthesis of chemical components for materials and the analysis of materials by electron microscopy, are highlighted. Two examples of beneficial effects of successful RDM strategies are presented, showing a sophisticated tool for data prediction based on machine learning and options for creating community‐driven databases by extracting and re‐using data from different scientific projects. [ABSTRACT FROM AUTHOR]

Layer‐by‐layer synthesis of surface‐coordinated metal–organic frameworks (SURMOF) enables the assembly of asymmetric, dipolar linkers into non‐centrosymmetric pillar‐layered structures. Using appropriate substrate terminations can yield oriented growth with the dipoles aligned perpendicular to the surface. The aligned pillar linkers give rise to a built‐in electrostatic field. In addition, the non‐centrosymmetric structure of the SURMOF gives rise to intriguing nonlinear optical features, such as second harmonic generation. Previous research with methyl‐functionalized bipyridine pillar linkers have demonstrated that this approach works in principle, but so far the total degree of alignment is only very small. Herein, a multiscale modelling approach is presented for in‐silico SURMOF assembly to identify and overcome limitations in the growth of pillar‐layered SURMOFs and to develop a strategy to maximize linker alignment. Using master equation models and kinetic Monte Carlo simulations, it is found that the formation of a highly ordered state corresponding to the thermodynamic equilibrium is often prevented by long‐lasting transient effects. Based on ab initio binding energies for a wide selection of hypothetical pillar linkers, a fast‐binding, slow‐relaxation scheme is able to be identified during the SURMOF growth for a range of different pillar linkers. These observations allow them to derive a rational strategy for the design of novel linkers to yield SURMOF‐based non‐centrosymmetric materials with substantially improved properties. [ABSTRACT FROM AUTHOR]

The development of new functional materials is crucial for addressing global challenges such as clean energy or the discovery of new drugs and antibiotics. Functional material systems are typically composed of functional molecular building blocks, organized across multiple length scales in a hierarchical order. The large design space allows for precise tuning of properties to specific applications, but also makes it time‐consuming and expensive to screen for optimal structures using traditional experimental methods. Machine learning (ML) models can potentially revolutionize the field of materials science by predicting chemical syntheses and materials properties with high accuracy. However, ML models require data to be trained and validated. Methods to automatically extract data from scientific literature make it possible to build large and diverse datasets for ML models. In this article, opportunities and challenges of data extraction and machine learning methods are discussed to accelerate the discovery of high‐performing functional material systems, while ensuring that the predicted materials are stable, synthesizable, scalable, and sustainable. The potential impact of large language models (LLMs) on the data extraction process are discussed. Additionally, the importance of research data management tools is discussed to overcome the intrinsic limitations of data extraction approaches. [ABSTRACT FROM AUTHOR]

Many properties of the emerging class of metal‐organic frameworks (MOFs) depend crucially on defect concentrations, as in case of other solids. In order to provide reference systems with nearly perfect structure and low defect density, a procedure to grow MOFs epitaxially on cm‐sized Si(111) single crystals is developed. The crystalline metal‐organic thin films are in high registry with the substrate's crystal lattice, as demonstrated by synchrotron‐based grazing incidence X‐ray diffraction (GI‐XRD) experiments. The corresponding reduction of MOF defect density is shown to have striking effects on the properties of these porous frameworks. The most pronounced difference concerns mass transport. An increase in the diffusion coefficient of guest molecules by one order of magnitude relative to the same MOF materials with normal defect densities is observed. [ABSTRACT FROM AUTHOR]

Electronic circular dichroism is an important optical phenomenon offering insights into chiral molecular materials. On the other hand, metal–organic frameworks (MOFs) are a novel group of crystalline porous thin‐film materials that provide tailor‐made chemical and physical properties by carefully selecting their building units. Combining these two aspects of contemporary material research and integrating chiral molecules into MOFs promises devices with unprecedented functionality. However, considering the nearly unlimited degrees of freedom concerning the choice of materials and the geometrical details of the possibly structured films, urgently it needs to complement advanced experimental methods with equally strong modeling techniques. Most notably, these modeling techniques must cope with the challenge that the material and devices thereof cover size scales from Ångströms to mm. In response to that need, a computational workflow is outlined that seamlessly combines quantum chemical methods to capture the properties of individual molecules with optical simulations to capture the properties of functional devices made from these molecular materials. The focus is on chiral properties and applying work to UiO‐67‐BINOL MOFs, for which experimental results are available to benchmark the results of the simulations and explore the optical properties of cavities and metasurfaces made from that chiral material. [ABSTRACT FROM AUTHOR]

Electron‐phonon interactions, crucial in condensed matter, are rarely seen in Metal–Organic Frameworks (MOFs). Detecting these interactions typically involves analyzing luminescence in lanthanide‐ or actinide‐based compounds. Prior studies on Ln‐ and Ac‐based MOFs at high temperatures revealed additional peaks, but these were too faint for thorough analysis. In our research, we fabricated a high‐quality, crystalline uranium‐based MOF (KIT‐U‐1) thin film using a layer‐by‐layer method. Under UV light, this film showed two distinct "hot bands," indicating a strong electron‐phonon interaction. At 77 K, these bands were absent, but at 300 K, a new emission band appeared with half the intensity of the main luminescence. Surprisingly, a second hot band emerged above 320 K, deviating from previous findings in rare‐earth compounds. We conducted a detailed ab‐initio analysis employing time‐dependent density functional theory to understand this unusual behaviour and to identify the lattice vibration responsible for the strong electron‐phonon coupling. The KIT‐U‐1 film's hot‐band emission was then utilized to create a highly sensitive, single‐compound optical thermometer. This underscores the potential of high‐quality MOF thin films in exploiting the unique luminescence of lanthanides and actinides for advanced applications. [ABSTRACT FROM AUTHOR]

Organic semiconductors, specifically polycyclic aromatic chromophores like pentacene, coronene, and nanographenes (hexa‐peri‐hexabenzocoronene, HBC), are often utilized in optoelectronic applications due to their intriguing single‐molecule properties. However, the integration of these aromatic compounds into optoelectronic devices frequently encounters significant obstacles, primarily due to the unpredictable and challenging control over the structure and morphology of their condensed phase. Rather than resorting to chemical modifications or advanced thin‐film manufacturing methods such as chemical vapor deposition, the so‐called metal‐organic framework (MOF) approach is employed to create a highly photoresponsive, nanographene‐based thin film employing a layer‐by‐layer, liquid‐phase epitaxy method. It is demonstrated that the novel Cu‐HBC MOF thin film exhibits excellent photoresponsive behavior under ultraviolet illumination, including a fast response time (˂ 0.02 s) and high current switching ratio (≈104), which significantly outperforms an isostructural MOF Zn‐HBC. Furthermore, it is demonstrated that the metal nodes inside the MOF can be used to enhance the photoresponse by efficient exciton splitting. [ABSTRACT FROM AUTHOR]

Metal–organic frameworks (MOFs) have gained substantial attention as promising materials for gas separation membranes due to their exceptional porosity, tailorability, and functionalizability. In this study, we present a novel approach to further enhance the properties of porous polymer membranes emerging from MOFs through crosslinking of the organic linker molecules and subsequent metal-atom removal. To ensure reproducibility of the multi-step synthesis process and high quality of the resulting polymeric membranes, we automated the process and followed a machine learning optimization approach. The high-quality MOF-thin films (SURMOFs) were prepared in a layer-by-layer fashion directly on gold-coated porous alumina substrates. This direct synthesis proved crucial to preserve the structural integrity of the membranes and thus avoiding defect formation caused by a substrate-transfer process, which is usually required when advanced materials are used to fabricate a membrane. The initial SURMOF membrane exhibits moderate gas separation performance, once crosslinked, its gas selectivity could be significantly enhanced although with the compromise of lower gas permeance. Interestingly, once we removed the metal centers and thereby converted the SURMOF into a purely organic polymeric membrane, the membrane gas permeance could be restored almost to its initial condition while preserving the enhanced selectivities. In particular, the resulting polymeric membrane outperforms most commercially available polymer membranes for H2/CO2 gas separation. This research outlines a promising approach to employ MOFs as template in the generation of advanced polymer membranes for various gas and liquid phase separation applications. [ABSTRACT FROM AUTHOR]

The unique properties of 2D‐materials like graphene are exploited in various electronic devices. In sensor applications, graphene shows a very high sensitivity, but only a low specificity. This shortcoming can be mastered by using heterostructures, where graphene is combined with materials exhibiting high analyte selectivities. Herein, this study demonstrates the precise deposition of nanoporous metal‐organic frameworks (MOFs) on graphene, yielding bilayers with excellent specificity while the sensitivity remains large. The key for the successful layer‐by‐layer deposition of the MOF films (SURMOFs) is the use of planar polyaromatic anchors. Then, the MOF pores are loaded with ionic liquid (IL). For functioning sensor devices, the IL@MOF films are grown on graphene field‐effect transistors (GFETs). Adding a top‐gate electrode yields an ion‐gated GFET. Analysis of the transistor characteristics reveals a clear Dirac point at low gate voltages, good on‐off ratios, and decent charge mobilities and densities in the graphene channel. The GFET‐sensor reveals a strong and selective response. Compared to other ion‐gated‐FET devices, the IL@MOF material is relatively hard, allowing the manufacturing of ultrathin devices. The new MOF‐anchoring strategy offers a novel approach generally applicable for the functionalization of 2D‐materials, where MOF/2D‐material hetero‐bilayers carry a huge potential for a wide variety of applications. [ABSTRACT FROM AUTHOR]