Correction: Time-, space- and energy-resolved in situ characterization of catalysts by X-ray absorption spectroscopy.

Correction for 'Time-, space- and energy-resolved in situ characterization of catalysts by X-ray absorption spectroscopy' by Stefan Peters et al., Chem. Commun., 2023, 59, 12120-12123, https://doi.org/10.1039/D3CC03277A.

Fundamental Structural and Electronic Understanding of Palladium Catalysts on Nitride and Oxide Supports.

The nature of the support can fundamentally affect the function of a heterogeneous catalyst. For the novel type of isolated metal atom catalysts, sometimes referred to as single-atom catalysts, systematic correlations are still rare. Here, we report a general finding that Pd on nitride supports (non-metal and metal nitride) features a higher oxidation state compared to that on oxide supports (non-metal and metal oxide). Through thorough oxidation state investigations by X-ray absorption spectroscopy (XAS), X-ray photoelectron spectroscopy (XPS), CO-DRIFTS, and density functional theory (DFT) coupled with Bader charge analysis, it is found that Pd atoms prefer to interact with surface hydroxyl group to form a Pd(OH)x species on oxide supports, while on nitride supports, Pd atoms incorporate into the surface structure in the form of Pd-N bonds. Moreover, a correlation was built between the formal oxidation state and computational Bader charge, based on the periodic trend in electronegativity.

Cobalt nanoparticle-catalysed N-alkylation of amides with alcohols.

A protocol for efficient N-alkylation of benzamides with alcohols in the presence of cobalt-nanocatalysts is described. Key to the success of this general methodology is the use of highly dispersed cobalt nanoparticles supported on carbon, which are obtained from the pyrolysis of cobalt(ii) acetate and o-phenylenediamine as a ligand at suitable temperatures. The catalytic material shows a broad substrate scope and good tolerance to functional groups. Apart from the synthesis of a variety of secondary amides (>45 products), the catalyst allows for the conversion of more challenging aliphatic alcohols and amides, including biobased and macromolecular amides. The practical applicability of the catalyst is underlined by the successful recycling and reusability.

Fundamentals of Unanticipated Efficiency of Gd2O3-based Catalysts in Oxidative Coupling of Methane.

Improving the selectivity in the oxidative coupling of methane to ethane/ethylene poses a significant challenge for commercialization. The required improvements are hampered by the uncertainties associated with the reaction mechanism due to its complexity. Herein, we report about 90 % selectivity to the target products at 11 % methane conversion over Gd2O3-based catalysts at 700 °C using N2O as the oxidant. Sophisticated kinetic studies have suggested the nature of adsorbed oxygen species and their binding strength as key parameters for undesired methane oxidation to carbon oxides. These descriptors can be controlled by a metal oxide promoter for Gd2O3.

Heterogenized Molecular Electrocatalyst Based on a Hydroxo-Bridged Binuclear Copper(II) Phenanthroline Compound for Selective Reduction of CO2 to Ethylene.

Molecular copper catalysts have emerged as promising candidates for the electrochemical reduction of CO2 . Notable features of such systems include the ability of Cu to generate C2+  products and the well-defined active sites that allow for targeted structural tuning. However, the frequently observed in situ formation of Cu nanoclusters has undermined the advantages of the molecular frameworks. It is therefore desirable to develop Cu-based catalysts that retain their molecular structures during electrolysis. In this context, a heterogenized binuclear hydroxo-bridged phenanthroline Cu(II) compound with a short Cu···Cu distance is reported as a simple yet efficient catalyst for electrogeneration of ethylene and other C2 products. In an aqueous electrolyte, the catalyst demonstrates remarkable performance, with excellent Faradaic efficiency for C2 products (62%) and minimal H2 evolution (8%). Furthermore, it exhibits high stability, manifested by no observable degradation during 15 h of continuous electrolysis. The preservation of the atomic distribution of the active sites throughout electrolysis is substantiated through comprehensive characterizations, including X-ray photoelectron and absorption spectroscopy, scanning and transmission electron microscopy, UV-vis spectroscopy, as well as control experiments. These findings establish a solid foundation for further investigations into targeted structural tuning, opening new avenues for enhancing the catalytic performance of Cu-based molecular electrocatalysts.

A general and robust Ni-based nanocatalyst for selective hydrogenation reactions at low temperature and pressure.

Catalytic hydrogenations are important and widely applied processes for the reduction of organic compounds both in academic laboratories and in industry. To perform these reactions in sustainable and practical manner, the development and applicability of non-noble metal-based heterogeneous catalysts is crucial. Here, we report highly active and air-stable nickel nanoparticles supported on mesoporous silica (MCM-41) as a general and selective hydrogenation catalyst. This catalytic system allows for the hydrogenation of carbonyl compounds, nitroarenes, N-heterocycles, and unsaturated carbon─carbon bonds in good to excellent selectivity under very mild conditions (room temperature to 80°C, 2 to 10 bar H2). Furthermore, the optimal nickel/meso-silicon dioxide catalyst is reusable (4 cycles) without loss of its catalytic activity.

Experiment and Theory in Concert To Unravel the Remarkable Electronic Properties of Na-Doped Eu11Zn4Sn2As12: A Layered Zintl Phase.

Low-dimensional materials have unique optical, electronic, mechanical, and chemical properties that make them desirable for a wide range of applications. Nano-scaling materials to confine transport in at least one direction is a common method of designing materials with low-dimensional electronic structures. However, bulk materials give rise to low-dimensional electronic structures when bonding is highly anisotropic. Layered Zintl phases are excellent candidates for investigation due to their directional bonding, structural variety, and tunability. However, the complexity of the structure and composition of many layered Zintl phases poses a challenge for producing phase-pure bulk samples to characterize. Eu11Zn4Sn2As12 is a layered Zintl phase of significant complexity that is of interest for its magnetic, electronic, and thermoelectric properties. To prepare phase-pure Eu11-xNaxZn4Sn2As12, a binary EuAs phase was employed as a precursor, along with NaH. Experimental measurements reveal low thermal conductivity and a high Seebeck coefficient, while theoretical electronic structure calculations reveal a transition from a 3D to 2D electronic structure with increasing carrier concentration. Simulated thermoelectric properties also indicate anisotropic transport, and thermoelectric property measurements confirm the nonparabolicity of the relevant bands near the Fermi energy. Thermoelectric efficiency is known to improve as the dimensionality of the electronic structure is decreased, making this a promising material for further optimization and opening the door to further exploitation of layered Zintl phases with low-dimensional electronic structures for thermoelectric applications.

Time-, space- and energy-resolved in situ characterization of catalysts by X-ray absorption spectroscopy.

A setup for dispersive X-ray absorption spectroscopy (XAS) with spatial, temporal and energy resolution is presented. Through investigation of a Mo/HZSM-5 catalyst during the dehydroaromatization of methane we observed a reduction gradient along the packed bed. Our new method represents an unprecedented addition to the analytical toolbox for in situ characterizations.

Tailoring Active Cu2 O/Copper Interface Sites for N-Formylation of Aliphatic Primary Amines with CO2 /H2.

Heterogeneously catalyzed N-formylation of amines to formamide with CO2 /H2 is highly attractive for the valorization of CO2 . However, the relationship of the catalytic performance with the catalyst structure is still elusive. Herein, mixed valence catalysts containing Cu2 O/Cu interface sites were constructed for this transformation. Both aliphatic primary and secondary amines with diverse structures were efficiently converted into the desired formamides with good to excellent yields. Combined ex and in situ catalyst characterization revealed that the presence of Cu2 O/Cu interface sites was vital for the excellent catalytic activity. Density functional theory (DFT) calculations demonstrated that better catalytic activity of Cu2 O/Cu(111) than Cu(111) is attributed to the assistance of oxygen at the Cu2 O/Cu interface (Ointer ) in formation of Ointer -H moieties, which not only reduce the apparent barrier of HCOOH formation but also benefit the desorption of the desired N-formylated amine, leading to high activity and selectivity.

Development of a General and Selective Nanostructured Cobalt Catalyst for the Hydrogenation of Benzofurans, Indoles and Benzothiophenes.

The selective hydrogenation of benzofurans in the presence of a heterogeneous non-noble metal catalyst is reported. The developed optimal catalytic material consists of cobalt-cobalt oxide core-shell nanoparticles supported on silica, which has been prepared by the immobilization and pyrolysis of cobalt-DABCO-citric acid complex on silica under argon at 800 °C. This novel catalyst allows for the selective hydrogenation of simple and functionalized benzofurans to 2,3-dihydrobenzofurans as well as related heterocycles. The versatility of the reported protocol is showcased by the reduction of selected drugs and deuteration of heterocycles. Further, the stability, recycling, and reusability of the Co-nanocatalyst are demonstrated.

Oxidative dehydrogenation of cyclohexene on atomically precise subnanometer Cu4-nPdn (0 ≤ n ≤ 4) tetramer clusters: the effect of cluster composition and support on performance.

The pronounced effects of the composition of four-atom monometallic Cu and Pd and bimetallic CuPd clusters and the support on the catalytic activity and selectivity in the oxidative dehydrogenation of cyclohexene are reported. The ultra-nanocrystalline diamond supported clusters are highly active and dominantly produce benzene; some of the mixed clusters also produce cyclohexadiene, which are all clusters with a much suppressed combustion channel. The also highly active TiO2-supported tetramers solely produce benzene, without any combustion to CO2. The selectivity of the zirconia-supported mixed CuPd clusters and the monometallic Cu cluster is entirely different; though they are less active in comparison to clusters with other supports, these clusters produce significant fractions of cyclohexadiene, with their selectivity towards cyclohexadiene gradually increasing with the increasing number of copper atoms in the cluster, reaching about 50% for Cu3Pd1. The zirconia-supported copper tetramer stands out from among all the other tetramers in this reaction, with a selectivity towards cyclohexadiene of 70%, which far exceeds those of all the other cluster-support combinations. The findings from this study indicate a positive effect of copper on the stability of the mixed tetramers and potential new ways of fine-tuning catalyst performance by controlling the composition of the active site and via cluster-support interactions in complex oxidative reactions under the suppression of the undesired combustion of the feed.

How droplets move on laser-structured surfaces: Determination of droplet adhesion forces on nano- and microstructured surfaces.

HYPOTHESIS: Lateral adhesion forces are a fundamental property of liquid-solid interactions and a key aspect of dynamic droplet mobility. But, commonly applied conventional wetting analysis is limited to static and quasi-static methods and cannot resolve dynamic and spatial liquid-solid interactions. However, droplet mobility is assumed to be affected by chemical and topographic surface inhomogeneities introduced by femtosecond laser treatment. EXPERIMENTS: In this study, we used a customized droplet adhesion force instrument to determine lateral adhesion forces on various femtosecond laser-structured surface designs to obtain a deeper understanding of the dynamic droplet motion with regard to chemical and topographic surface features. FINDINGS: We show that the droplet motion was highly affected by the chemical and topographical surface design and local inhomogeneities. The droplet mobility on femtosecond laser-structured surfaces could be classified into a static, a transfer, and a kinetic regime, which is essential for designing surfaces with extreme wetting characteristics and a wide range of scientific and industrial processes. Furthermore, with proper tailoring of surface structures and chemical modification, we were able to provoke adhesion forces on self-organized laser microstructures similar to those found on the natural lotus leaves.

Stable and reusable Ni-based nanoparticles for general and selective hydrogenation of nitriles to amines.

Silica supported ultrasmall Ni-nanoparticles allow for general and selective hydrogenation of all kinds of nitriles to primary amines under mild conditions. By calcination of a template material generated from Ni(ii)nitrate and colloidal silica under air and subsequent reduction in the presence of molecular hydrogen the optimal catalyst is prepared. The prepared supported nanoparticles are stable, can be conveniently used and easily recycled. The applicability of the optimal catalyst material is shown by hydrogenation of >110 diverse aliphatic and aromatic nitriles including functionalized and industrially relevant substrates. Challenging heterocyclic nitriles, specifically cyanopyridines, provided the corresponding primary amines in good to excellent yields. The resulting amines serve as important precursors and intermediates for the preparation of numerous life science products and polymers.

Mild and Efficient Heterogeneous Hydrogenation of Nitroarenes Facilitated by a Pyrolytically Activated Dinuclear Ni(II)-Ce(III) Diimine Complex.

We communicate the assembly of a solid, Ce-promoted Ni-based composite that was applied as catalyst for the hydrogenation of nitroarenes to afford the corresponding organic amines. The catalytically active material described herein was obtained through pyrolysis of a SiO2-pellet-supported bimetallic Ni-Ce complex that was readily synthesized prior to use from a MeO-functionalized salen congener, Ni(OAc)2·4 H2O, and Ce(NO3)3·6 H2O. Rewardingly, the requisite ligand for the pertinent solution phase precursor was accessible upon straightforward and time-saving imine condensation of ortho-vanillin with 1,3-diamino-2,2'-dimethylpropane. The introduced catalytic protocol is operationally simple in that the whole reaction set-up is quickly put together on the bench without the need of cumbersome handling in a glovebox or related containment systems. Moreover, the advantageous geometry and compact-sized nature of the used pellets renders the catalyst separation and recycling exceptionally easy.

Diastereoselective hydrogenation of arenes and pyridines using supported ruthenium nanoparticles under mild conditions.

A convenient and practical diastereoselective cis-hydrogenation of multi-substituted pyridines and arenes is reported. Applying a novel heterogeneous ruthenium catalyst, the corresponding piperidines and cyclohexanes are obtained in high yields (typically >80%) with a good functional group tolerance under mild conditions. The robust ruthenium supported catalyst is smoothly prepared and can be reused multiple times without activity loss.

Manganese-Catalysed Deuterium Labelling of Anilines and Electron-Rich (Hetero)Arenes.

There is a constant need for deuterium-labelled products for multiple applications in life sciences and beyond. Here, a new class of heterogeneous catalysts is reported for practical deuterium incorporation in anilines, phenols, and heterocyclic substrates. The optimal material can be conveniently synthesised and allows for high deuterium incorporation using deuterium oxide as isotope source. This new catalyst has been fully characterised and successfully applied to the labelling of natural products as well as marketed drugs.

Oxygen vacancies in Ru/TiO2 - drivers of low-temperature CO2 methanation assessed by multimodal operando spectroscopy.

Hydrogenation of CO2 is very attractive for transforming this greenhouse gas into valuable high energy density compounds. In this work, we developed a highly active and stable Ru/TiO2 catalyst for CO2 methanation prepared by a solgel method that revealed much higher activity in methanation of CO2 (ca. 4-14 times higher turnover frequencies at 140-210°C) than state-of-the-art Ru/TiO2 catalysts and a control sample prepared by wetness impregnation. This is attributed to a high concentration of O-vacancies, inherent to the solgel methodology, which play a dual role for 1) activation of CO2 and 2) transfer of electrons to interfacial Ru sites as evident from operando DRIFTS and in situ EPR investigations. These results suggest that charge transfer from O-vacancies to interfacial Ru sites and subsequent electron donation from filled metal d-orbitals to antibonding orbitals of adsorbed CO are decisive factors in boosting the CO2 methanation activity.

Scalable and selective deuteration of (hetero)arenes.

Isotope labelling, particularly deuteration, is an important tool for the development of new drugs, specifically for identification and quantification of metabolites. For this purpose, many efficient methodologies have been developed that allow for the small-scale synthesis of selectively deuterated compounds. Due to the development of deuterated compounds as active drug ingredients, there is a growing interest in scalable methods for deuteration. The development of methodologies for large-scale deuterium labelling in industrial settings requires technologies that are reliable, robust and scalable. Here we show that a nanostructured iron catalyst, prepared by combining cellulose with abundant iron salts, permits the selective deuteration of (hetero)arenes including anilines, phenols, indoles and other heterocycles, using inexpensive D2O under hydrogen pressure. This methodology represents an easily scalable deuteration (demonstrated by the synthesis of deuterium-containing products on the kilogram scale) and the air- and water-stable catalyst enables efficient labelling in a straightforward manner with high quality control.

Copper-catalysed low-temperature water-gas shift reaction for selective deuteration of aryl halides.

The introduction of deuterium atoms into organic compounds is of importance for basic chemistry, material sciences, and the development of drugs in the pharmaceutical industry, specifically for identification and quantification of metabolites. Hence, methodologies for the synthesis of selectively labelled compounds continue to be a major area of interest for many scientists. Herein, we present a practical and stable heterogeneous copper catalyst, which permits for dehalogenative deuteration via water-gas shift reaction at comparably low temperature. This novel approach allows deuteration of diverse (hetero)aryl halides with good functional group tolerance, and no reduction of the aromatic rings or other easily reducible formyl and cyano groups. Multi-gram experiments show the potential of this method in organic synthesis and medicinal chemistry.

Color Tuning of Electrochromic TiO2 Nanofibrous Layers Loaded with Metal and Metal Oxide Nanoparticles for Smart Colored Windows.

Co-axial electrospinning was applied for the structuring of non-woven webs of TiO2 nanofibers loaded with Ag, Au, and CuO nanoparticles. The composite layers were tested in an electrochromic half-cell assembly. A clear correlation between the nanoparticle composition and electrochromic effect in the nanofibrous composite is observed: TiO2 loaded with Ag reveals a black-brown color, Au shows a dark-blue color, and CuO shows a dark-green color. For electrochromic applications, the Au/TiO2 layer is the most promising choice, with a color modulation time of 6 s, transmittance modulation of 40%, coloration efficiency of 20 cm2/C, areal capacitance of 300 F/cm2, and cyclic stability of over 1000 cycles in an 18 h period. In this study, an unexplored path for the rational design of TiO2-based electrochromic device is offered with unique color-switching and optical efficiency gained by the fibrous layer. It is also foreseen that co-axial electrospinning can be an alternative nanofabrication technique for smart colored windows.