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The need to develop clean-energy storage systems, harvesting technologies, and new functional materials are but a few of the many contemporary challenges in the domain of science today. To address these challenges, problem solving has become a key skill of the 21st century. It is generally documented, however, that experts and students differ in terms of their problem-solving skills. Experts in a domain are fluent in the use of different resources to solve domain-specific problems, whereas students stumble when using formulas, devices, or measurement methods. In most cases, the students are not aware if and why the resources are appropriate to solve the given problem. To acquire expertise in a domain, it is necessary to become fluent in the domain-specific resources. This means being aware of various resources and how they can be used reflectively in problem solving. In this study, we investigated how students' awareness of various domain-specific resources developed within minimally guided, authentic research projects in an undergraduate materials chemistry course that focuses on crystal structures and its characterisation. By monitoring participants' problem solving through audio-diaries and in-depth qualitative interview data, we examined to what extent their awareness of domain-specific resources developed. We further characterised productive moments of failure and uncertainty during students' problem-solving processes that influenced their awareness. Thick descriptions of these moments facilitate understanding of how students' awareness develops in a minimally guided, authentic learning environment and how students can become fluent in a given domain. [ABSTRACT FROM AUTHOR]

A parametrization algorithm to determine chord-length distributions (CLD) from small-angle scattering data is used to characterize details of the pore structure, pore size, and morphology of porous carbon materials. This approach is applied to various carbon processing procedures, such as steam activation, tempering, and contacting with polymer binders. It is found that this CLD method reveals, compared to previous small angle x-ray scattering evaluation approaches, fine changes in the pore structure and morphology of porous carbons with higher accuracy and physical significance. © 2002 American Institute of Physics. [ABSTRACT FROM AUTHOR]

In recent years, the usage of ionic liquids (ILs) in the synthesis of metal oxides has been extensively studied, especially with respect to their possible advantageous effects in comparison to conventional syntheses protocols. Herein, an overview is given on the variety of different syntheses of TiO2-based materials, which correlates to the diversity of different ionic liquids. Special emphasis is put on the historic development of the IL-based synthesis of TiO2 materials in the general context of research on IL-based materials synthesis. Also, the assumed advantages of both, the synthesis and the resulting TiO2 materials, are critically revised. It can be concluded that the application of ILs exerts a direct influence on several parameters, namely the phase composition, the dopants or the nanostructuring of the material. Importantly, the research on TiO2-based materials enables fundamental insights into IL-specific effects in the synthesis of inorganic materials in general. [ABSTRACT FROM AUTHOR]

Mesostructured oxide films were prepared by dip-coating from colloidal solutions on ultrathin Si wafers and solidified by heating at various temperatures. Two-dimensional small-angle X-ray scattering measurements were carried out in transmission under selected tilt angles and evaluated by comparison with analytical expressions. The films are composed of oriented mesophases, the structures of which are defined in terms of lattice type, preferred orientation, deformation and imperfection, notably stacking faults. [ABSTRACT FROM AUTHOR]

Abstract: Non-graphitic carbon materials produced by pyrolyzing wood at temperatures from 400 to 2400°C and various types of commercial carbon fibers were examined by X-ray diffraction and Raman spectroscopy. The specimens cover a wide range of crystallite sizes L a, in particular also very small sizes below 2nm. The X-ray data were evaluated using the Scherrer equation and by an advanced approach using full curve fitting. The ratio of the D/G band intensities was determined from the Raman data by different evaluation techniques. A critical assessment of the classical linear relationship between 1/L a and the D/G ratio shows that the relationship breaks down for crystallite sizes below 2nm in accordance with recent theoretical predictions. The results are compared with data from the literature, showing that there are additional discrepancies between the data from various carbon types at large L a due to different methods of data evaluation. [Copyright &y& Elsevier]

In a recent paper [Ruland & Smarsly (2002). J. Appl. Cryst. 35, 624–633], an advanced method for the evaluation of the small-angle X-ray scattering (SAXS) from oriented lamellar systems was presented. In the present work, a comparable method is developed for the study of oriented cylinder arrays. Basic differences between the two methods are found in the way in which the preferred orientation affects the intensity distribution. The method is applied to the SAXS of SiO2-surfactant nanocomposite films which contain highly oriented arrays of cylinders. It is shown that up to eight structural parameters can be obtained by this method which characterize size, imperfection and preferred orientation of the two-dimensional hexagonal lattice formed by the cylinders, the radius and the polydispersity of the cylinders, and the interface boundary. [ABSTRACT FROM AUTHOR]

Oriented lamellar nanocomposites formed of alternating organic and inorganic layers were prepared by evaporation-induced self-assembly and studied by small-angle X-ray scattering in symmetrical and asymmetrical reflection. Analytical expressions were used for a quantitative fit of the experimental data. The fitting procedure leads to a comprehensive characterization of the lamellar two-phase system in terms of the average thicknesses of the lamellae, the average period and the corresponding variances, using both the stacking model and the lattice model. Furthermore, the width of the domain boundary and the preferred orientation were determined. No significant differences could be found between the parameters obtained for the two models, but the lattice model leads to a better curve fitting. The effects of finite stack height and of instrumental broadening were found to be indistinguishable. [ABSTRACT FROM AUTHOR]

Porous silica materials were prepared through nanocasting of stable isolated pseudopolyrotaxanes from α-cyclodextrin and polyamines. The characterization by transmission electron microscopy, nitrogen sorption and small angle X-ray scattering shows that the obtained silica materials possess quite high porosity and elongated pores. [Copyright &y& Elsevier]

In 1987, Rius, Plana & Palanques [J. Appl. Cryst. (1987), 20,457-460] devised an X-ray powder diffraction method based on the 'least-squares' determination of calibration constants using only the diffracted intensities and the calculated absorption coefficients of the components. This method was developed for 'infinitely thick' samples, a condition which is seldom met by airborne particulates because of the small amount of material normally available. Since the analysis of such samples may become one of the principal applications of the method, this condition represents a serious limitation. The simplest way to overcome this limitation is by correcting the measured intensities. This can be done either by direct measurement of the sample transmission, or alternatively, by using refined transmission values. In the latter case no experimental values are necessary. With the help of some test calculations, the viability of both possibilities has been explored. [ABSTRACT FROM AUTHOR]

MoS2 and WS2 have gathered significant attention due to their tunable properties and wide range of applications. Liquid‐phase exfoliation (LPE) is a facile method to prepare 2D MoS2 and WS2. Currently, the principally employed solvents for LPE of MoS2 and WS2 are expensive and toxic, and have high boiling points. These drawbacks encourage to find more sustainable alternatives to the liquid medium used for the preparation of 2D material inks. Water is the best option, but surfactants are necessary for LPE in water, since MoS2 and WS2 are hydrophobic. Organic molecules with amphoteric character such as sodium dodecyl sulfate, sodium dodecylbenzene sulfonate, and sodium hexadecyl sulfonate (SHS) are selected as suitable candidates for the role. However, the study of these surfactants used in LPE is barely systematically reported. In this work, a detailed investigation is presented on their impact on the LPE of MoS2 and WS2, which are representatives of transition‐metal dichalcogenides. By characterizing and qualifying the products from average number of layers, it is found that all the surfactants work efficiently to exfoliate MoS2 and WS2 into few layers, and SHS stabilizes the 2D layers better than the other two. However, in terms of yield and relative surfactant concentration, a real trade‐off is not identified between maximized quantity of exfoliated materials and minimized surfactant concentration, which prompts to select the colloidal ink based on the specific further needs for processing. [ABSTRACT FROM AUTHOR]

In this study, the preparation of anatase TiO2 nanocrystals via a facile non-aqueous sol–gel route and their characterization are reported. The 3–4 nm particles are readily dispersable in aqueous media and show excellent photoreactivity in terms of rhodamine B degradation. The catalytic performance can be further increased considerably by doping with iron and UV-light irradiation as a pre-treatment. The effect of surface ligands (blocked adsorption sites, surface defects etc.) on the photoreactivity was thoroughly probed using thermogravimetric analysis combined with mass spectrometry. Photoelectrochemical characterization of thin-film electrodes made from the same TiO2 nanocrystals showed the opposite trend to the catalytic experiments, that is, a strong decrease in photocurrent and quantum efficiency upon doping due to introduction of shallow defect states. [ABSTRACT FROM AUTHOR]

Organocatalysis via the enamine mechanism developed to one of the most relevant tools in carbonyl chemistry and is widely used in asymmetric organic synthesis. In this work, a strategy is presented to conveniently immobilize a peptide‐based catalyst on silica supports for use in continuous flow catalysis reactions. A set of different porous silica supports is investigated spanning from mesoporous silica particles with defined pore sizes suitable for packed bed column reactors to silica monoliths with hierarchical meso‐macropore spaces. While the silica supports are functionalized with norbornene entities, the peptide‐based organocatalyst is modified with a tetrazine moiety, enabling the immobilization via inverse electron‐demand Diels‐Alder (IEDDA) reaction. The ligation results in catalyst loadings up to 0.2 mmol g‐1, without compromising the mesopore network. The catalytic activity of the materials is proven by the asymmetric C−C coupling reaction of n‐butanal to ß‐nitrostyrene proceeding in high yield and enantioselectivity in both batch and continuous flow setups. [ABSTRACT FROM AUTHOR]

A rational synthetic approach is introduced to enable hydrogen insertion into oxides by forming a solid solution of a reducible oxide with a less reducible oxide as exemplified with RuO2 and TiO2 (Ru_x, a mixture of x% RuO2 with (100−x)% TiO2). Hydrogen exposure at 250 °C to Ru_x (Ru_x_250R) results in substantial hydrogen incorporation accompanied by lattice strain that in turn induces pronounced activity variations. Here, we demonstrate that hydrogen incorporation in mixed oxides promotes the oxidation catalysis of propane combustion with Ru_60_250R being the catalytically most active catalyst. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • TiO 2 nanoparticle multiphase heterojunctions have been prepared from ionic liquids. • Heterojunctions of bronze-TiO 2 and anatase are formed at different ratios. • Control of the TiO 2 (B)/anatase ratio solely by IL mixture. • 3:2 ratio of TiO 2 (B)/anatase exhibits highest hydrogen evolution performance. • Physical mixtures (3:2) cannot compete with the in-situ prepared heterojunction. Abstract We report on the immense influence of interfacial contact on the photocatalytic performance of TiO 2 nanoparticle multiphase heterojunctions. The composition of anatase and TiO 2 (B) in the final nanoparticles can be tuned, depending on the mixture of different Ionic Liquids. A ratio of 3:2 TiO 2 (B) to anatase exhibits the most pronounced enhancement in photocatalytic hydrogen evolution activity. As a comparative study, different physical mixtures in the ratio of 3:2 have been investigated in order to prove the formation of the heterojunction between anatase and TiO 2 (B). None of the physical mixtures can reach similar hydrogen evolution rates as the IL-based, in-situ prepared mixture proving the beneficial impact of interphase connections on charge carrier separation and therefore on photocatalytic efficiency by suppression of charge carrier recombination. [ABSTRACT FROM AUTHOR]

Studies the self assembly of an environmentally-responsive nanocomposite of polymer and silica. Key issues of interest; Analysis of pertinent topics and relevant issues; Implications on biochemistry.

CarbX is an open‐source program designed for the analysis of wide‐angle X‐ray scattering (WAXS) data of non‐graphitic carbons (NGCs). As knowledge of their microstructure is crucial for tuning desired properties, an `easy‐to‐use' analysis tool is essential for effective research in this field. Using CarbX one can retrieve up to 14 microstructural parameters from a single WAXS pattern without having to master the associated complicated mathematics. CarbX was developed to serve as a convenient graphical user interface, translating a complex evaluation algorithm introduced by Ruland & Smarsly [J. Appl. Cryst. (2002), 35, 624–633] into software which can be operated by non‐experts. Besides the core functionality of displaying data and manually fitting WAXS curves by user‐editable parameters, CarbX offers additional features such as visualization of the deviation between data and fit, the possibility to choose the wavelength used in the measurement, and automatic fitting (using Wolfram Mathematica). One of the key features of the comfortable usability is the functionality to display templates. This allows the user to visually compare measurement data with typical types of NGC WAXS curves which are presented graphically around the measurement data. The authors believe that this program will provide a useful tool for scientists dealing with the characterization of NGCs. [ABSTRACT FROM AUTHOR]

The majority of particle synthesis methods are based on nucleation and growth processes in solvents. Whereas the role of capping agents has been investigated extensively regarding control particle size and shape, the unique role of the solvent is understood to a much lesser extent. Compared to other polar solvents, e.g. water, ionic liquids (ILs) are unique because their properties can be fine-tuned precisely by appropriate choice and modification of cation and anion. This makes ILs also interesting for particle synthesis. We present the generation of zinc oxide (ZnO) in imidazolium ILs starting from molecular precursors. A hydrolytic, sol-gel based synthesis route is suitable to achieve nanocrystalline ZnO. We find by in-situ synchrotron wide angle X-ray diffraction that in ILs an unusual ZnO phase with α-boron nitride structure acts as an intermediate prior to crystallization of the thermodynamically stable Wurtzite. This special mechanism leads to organic-inorganic hybrid IL/ZnO nanoparticles with plate-like morphology. Because of the large content of IL embedded in the ZnO matrix the novel particles gain ionogel properties, e.g. ion conductivity probed by impedance spectroscopy. [ABSTRACT FROM AUTHOR]

The ortho-, meta- and para-isomers of bis(trimethoxysilyl)benzene and bis((trimethoxysilyl)phenyl)dimethoxysilane were synthesized from their corresponding diarylbromides. Mixtures of these bis(trimethoxysilyl)arenes and tetramethoxysilane (TMOS) were used as organosilica precursors for the preparation of macro-mesoporous silica monoliths using different amounts of the porogen poly(ethylene glycol) to investigate the effect on the porosity of the final materials. The prepared samples were characterized by nitrogen and dibromomethane sorption measurements, mercury intrusion porosimetry and scanning electron microscopy. The analysis of dibromomethane isotherms indicated a significantly lower polarity of the mesopore surface compared to that of pure SiO2 monoliths, proving the presence of arene units at the mesopore surfaces. [ABSTRACT FROM AUTHOR]

Semiconducting copper oxide (CuO) gas sensing layers show a remarkable conductance behavior if exposed to hydrogen sulfide (H 2 S) gas at low operating temperature (180 °C). At first conductance decreases as expected for a p-type semiconducting metal oxide offering reducing test gas. After a certain exposure time, however, a sudden steep increase in conductance can be observed. In a first approach this behavior is explained by the formation of metallic conducting copper sulfide (CuS, degenerate p-type semiconductor) clusters which eventually form conducting pathways across the sensing layers short-circuiting the remaining CuO phase. In the field of statistical physics such behavior can be described by the so-called percolation theory. Here we present a detailed experimental and theoretical analysis of the observed effect utilizing RF-magnetron-sputtered copper oxide films with different stoichiometry (CuO, Cu 4 O 3 and Cu 2 O) as model systems. The layers are exposed to H 2 S for different time spans and analyzed with respect to their morphology (SEM, XRD) and chemical composition (XPS, ToF-SIMS). Analysis of the transient behavior of the conductance by means of a percolation model and comparison of the results to the experimental data allow the identification of different processes. For CuO samples first the formation of different non-CuS copper–sulfur–oxygen phases is observed followed by the percolation regime with the steep conductance increase. Afterwards diffusion processes superimposing the percolation leading to a slower conductance increase and eventually the process is dominated by diffusion of copper ions from the bulk. For oxides with other stoichiometry (Cu 2 O, Cu 4 O 3 ) no percolation regime is observed which is attributed to higher diffusion rate of copper ions weakening the percolation effect in these samples. Based on these observations a model for the electronic conductance behavior of copper oxide gas sensors under exposure to hydrogen sulfide (H 2 S) at temperatures below 200 °C is proposed. A better understanding of these systems will enable the preparation of reliable sensors with inherent thresholds. [ABSTRACT FROM AUTHOR]

Long-term stability is a major issue in the development of new catalysts and in the improvement of existing catalysts. In general, high-surface-area materials in catalysis are not well suited as model materials for testing catalyst stability, because changes in the morphology are difficult to recognize with electron microscopy. Therefore, we developed a new type of model catalyst in the form of nanofibers for assessing structural changes of CeO 2 -based catalysts under highly corrosive Deacon reaction conditions. In the Deacon process, chlorine is recycled by heterogeneously catalyzed gas-phase oxidation of HCl, using metal oxide catalysts. The Deacon process generally suffers from degradation of the catalyst due to in-depth chlorination. One-dimensional CeO 2 -based nanofibers with a well-defined morphology and surface enable direct visualization of structural changes before and after the Deacon reaction, simply employing scanning electron microscopy supported by X-ray diffraction and physisorption measurements. Preparing solid solutions of CeO 2 and ZrO 2 has shown to improve both the chemical stability and the activity of the catalyst. [ABSTRACT FROM AUTHOR]

Mixed oxide catalysts RuxIr1‐xO2 with varying composition x (x=0, 0.25, 0.5, 0.75, 1.0) supported on CeO2, γ‐Al2O3 or ZrO2 are successfully prepared and tested in the catalytic propane combustion in terms of activity and stability. Pure IrO2 reveals a significantly lower activity than RuxIr1‐xO2 with x≥0.25. For low conversion, pure RuO2 on CeO2 turns out to be the most active catalyst, while at higher conversion, Ru0.75Ir0.25O2 on ZrO2 is found to be more active than RuO2, pointing towards synergism of Ru and Ir sites. Long‐term stability and also the resistance against water poisoning are highest for ZrO2‐supported catalysts. The higher the Ir concentration in the active component RuxIr1‐xO2 the more susceptible is the catalyst to water poisoning. Water poisoning is shown to be reversible, consistent with a blocking of catalytically active sites by water adsorption. [ABSTRACT FROM AUTHOR]

Here, we demonstrate that oxide thin film devices could be affected by humidity in their in-plane stress and in substrate curvature. We prepared silica glass and ceria crystalline thin films on Si(100) wafers by the sol-gel method. Both films had "tensile" in-plane residual stress. We cycled the relative humidity between ca. 20% and 80% in the square wave and monitored the substrate curvature in situ, from which in-plane stress was calculated. The increase and decrease in humidity resulted in a decrease and an increase in tensile stress, respectively. In situ ellipsometric measurements during humidity cycles showed that both thickness and refractive index increase and decrease on the increase and decrease in humidity, respectively. This guarantees that the volume expansion and shrinkage caused by water molecule adsorption/absorption and desorption, respectively, are the origins of the response of the stress to humidity. Responding to the change in humidity, thicker silica glass films with low porosities of 1%–3% showed more sluggish change in stress, suggesting absorption/desorption of water via diffusion in siloxane network in such dense films. Silica glass films with a larger porosity showed more quick response to humidity, indicating adsorption/desorption on the pore wall as the primary cause of the response. "Compressive" stress in a silica glass film with ca. 1% porosity exhibited very slight response in stress to humidity, which was attributed to the hard diffusion of water in compressed siloxane network. [ABSTRACT FROM AUTHOR]

We present a new concept for the detection of hydrogen sulfide (H2S) doses based on percolation effects in semiconducting (p-type) copper (II) oxide (CuO) thin films. Under H2S exposure at 180 °C CuO undergoes a chemical reaction to metallic conducting copper (II) sulfide (CuS). Reaching a certain dose of H2S (concentration × exposure time) the conductance increases rapidly by two orders of magnitude which is attributed to the formation of CuS percolation paths. This study focuses on the reproducibility of this effect as well as on theoretical modeling of the assumed underlying percolation mechanism. Analysis of conductance data reveals a behavior that is qualitatively very similar to standard scaling theory, but with a lower conductance exponent of µ ≈ 0.85 (instead of 1.3 for 2D systems). The deviation can be explained by a superimposing diffusion process and by deviations of the experimental systems from standard percolation systems. Nevertheless, the CuO thin films exhibit intrinsic structure controlled thresholds for H2S doses, which allows the utilization as H2S dosimeter. Conductance behavior of a CuO thin film exposed to 20 ppm H2S at 180 °C. The percolation threshold pc is reached 1054 s after start of the measurement. [ABSTRACT FROM AUTHOR]

We report the immobilization of 4‐dimethylaminopyridine (DMAP), a versatile organocatalyst for sterically demanding esterifications, on mesoporous silica particles and macro‐mesoporous silica monoliths, both possessing optimized properties for continuous flow synthesis. An alkyne‐functionalized DMAP derivative was immobilized via click chemistry; the materials were characterized by physisorption analysis, diffuse reflectance infrared Fourier transform spectroscopy (DRIFT) and elemental analysis. While silica particles were functionalized in batch and packed into a packed‐bed reactor, monoliths were cladded with a polyether ether ketone (PEEK) tube after sol‐gel synthesis and functionalized in a circulating flow process. Samples with three different catalyst loadings were prepared, in order to study the impact of the catalyst amount on the mesopore space as well as the catalytic performance. In continuous flow experiments, complete conversion of 1‐phenylethanol to phenylethylacetate was achieved with both materials and short contact times. Monoliths exhibited far lower pressures than packed bed reactors (7 bar at a flow rate of 1 mL min−1) and reached turnover rates up to 9.3x10−2 s−1, which is almost twice as high as a comparable batch experiment. The absence of diffusion limitations in monoliths made investigations on reaction kinetics with microkinetics‐dominated experiments possible. This study demonstrates that all properties needed for a successful transfer of immobilized organocatalysts to sophisticated flow syntheses with complex organocatalysts can be met with functionalized meso‐macroporous monoliths. [ABSTRACT FROM AUTHOR]

Well-ordered 3D mesoporous indium tin oxide (ITO) films obtained by a templated sol-gel route are discussed as conductive porous current collectors. This paper explores the use of such films modified by electrochemical deposition of zinc oxide (ZnO) on the pore walls to improve the electron transport in dye-sensitized solar cells (DSSCs). Mesoporous ITO film were dip-coated with pore sizes of 20-25 nm and 40-45 nm employing novel poly(isobutylene)-b-poly(ethylene oxide) block copolymers as structure-directors. After electrochemical deposition of ZnO and sensitization with the indoline dye D149 the films were tested as photoanodes in DSSCs. Short ZnO deposition times led to strong back reaction of photogenerated electrons from non-covered ITO to the electrolyte. ITO films with larger pores enabled longer ZnO deposition times before pore blocking occurred, resulting in higher efficiencies, which could be further increased by using thicker ITO films consisting of five layers, but were still lower compared to nanoporous ZnO films electrodeposited on flat ITO. The major factors that currently limit the application are the still low thickness of the mesoporous ITO films, too small pore sizes and non-ideal geometries that do not allow obtaining full coverage of the ITO surface with ZnO before pore blocking occurs. [ABSTRACT FROM AUTHOR]

The precise detection of the toxic gas H2S requires reliable sensitivity and specificity of sensors even at minute concentrations of as low as 10 ppm, the value corresponding to typical exposure limits. CuO can be used for H2S dosimetry, based on the formation of conductive CuS and the concomitant significant increase in conductance. In theory, at elevated temperature the reaction is reversed and CuO is formed, ideally enabling repeated and long‐term use of one sensor. Yet, the performance of CuO tends to drop upon cycling. Utilizing defined CuO nanorods we thoroughly elucidated the associated detrimental chemical changes directly on the sensors, by Raman and electron microscopy analysis of each step during sensing (CuO→CuS) and regeneration (CuS→CuO) cycles. We find the decrease in the sensing performance is mainly caused by the irreversible formation of CuSO4 during regeneration. The findings allowed us to develop strategies to reduce CuSO4 formation and thus to substantially maintain the sensing stability even for repeated cycles. We achieved CuO‐based dosimeters possessing a response time of a few minutes only, even for 10 ppm H2S, and prolonged life‐time. [ABSTRACT FROM AUTHOR]

Abstract: Analytical columns (4.6mm i.d.) packed with core–shell particles have shown a significantly reduced eddy dispersion contribution to band broadening compared to conventional fully porous particles. It has been speculated if this is caused by the narrow particle size distribution (PSD) of the core–shell particles, as an intrinsic advantage, or by an improved packing structure that specifically reduces the transcolumn velocity biases caused by wall effects. A recent simulation study has pointed against the former proposition [A. Daneyko et al., Anal. Chem. 83 (2011) 3903]. It is more likely that the slurry packing process for core–shell particles results in bed morphologies with reduced wall effects compared to the fully porous particles with a wide PSD. To access the latter proposition experimentally we slurry packed capillary columns (100μm i.d.) with different fully porous (wide PSDs) and core–shell (narrow PSDs) particles and imaged their bed structures three-dimensionally using confocal laser scanning microscopy. This allowed us to resolve and analyze the bed morphology in these columns locally on all length scales contributing to eddy dispersion. On the transcolumn scale we observed a systematic difference between core–shell and fully porous particles: In the vicinity of the column wall the core–shell particles packed denser (closer to the bulk packing densities) and with a higher regularity than the fully porous particles. The bulk regions of all packings were effectively indistinguishable. This provides experimental evidence that the reduced eddy dispersion contribution with core–shell packings should be attributed to a higher transcolumn homogeneity rather than to an improved bed morphology on smaller length scales, e.g., to a reduced short-range disorder. [Copyright &y& Elsevier]

A detailed study is given on the synthesis of a hierarchical porous carbon, possessing both meso- and macropores, using a mesophase pitch (MP) as the carbon precursor. This carbon material is prepared by the nanocasting approach involving the replication of a porous silica monolith (hard templating). While this carbon material has already been tested in energy storage applications, various detailed aspects of its formation and structure are addressed in this study. Scanning electron microscopy (SEM), Hg porosimetry and N2 physisorption are used to characterize the morphology and porosity of the carbon replica. A novel approach for the detailed analysis of wide-angle x-ray scattering (WAXS) from non-graphitic carbons is applied to quantitatively compare the graphene microstructures of carbons prepared using MP and furfuryl alcohol (FA). This WAXS analysis underlines the importance of the carbon precursor in the synthesis of templated porous carbon materials via the nanocasting route. Our study demonstrates that a mesophase pitch is a superior precursor whenever a high-purity, low-micropore-content and well-developed graphene structure is desired. [ABSTRACT FROM AUTHOR]

Abstract: We report an experimental study on the structural (especially radial) heterogeneity of eleven 100μm i.d. capillary tetramethoxysilane–methyltrimethoxysilane hybrid silica monoliths with different pore and skeleton sizes, which were imaged by an optimized confocal laser scanning microscopy method. This method allows the optical sectioning of the monoliths, which is a prerequisite for quantitative morphological image analysis. Both radial porosity profiles and chord length distributions were calculated in the macropore domain for each column from at least 100 complete cross-sectional views along the column axis. The statistical approach visualized radial heterogeneities on different length scales in the monolithic structures. Chord length distributions followed a simplified k-gamma function, and a structural parameter obtained from this function is introduced to provide a scalar measure of column heterogeneity. It enables the comparison of monoliths with different pore sizes and helps to establish correlations between the microscopic properties of a column, eddy dispersion, and its separation efficiency. [Copyright &y& Elsevier]

Porous LiFePO4has been prepared via a solution-based templating technique. Beads of poly(methyl methacrylate) were synthesized with diameters of 100, 140, and 270 nm and used to form colloidal crystal templates to produce LiFePO4, which featured pores spanning from 10 to 100 nm. The use of colloidal crystal templates allowed an examination of the effects of pore size on the electrochemical properties. The templated LiFePO4samples were fully characterized using SEM, TEM, XRD, Rietveld analysis, and nitrogen sorption prior to electrochemical testing. The materials with the largest pores, around 100 nm diameter, gave the best discharge capacities, with 160 mA h g−1at 0.1Cand 115 mA h g−1at 5Cbeing achieved. This compares with a theoretical discharge capacity of 170 mA h g−1. [ABSTRACT FROM AUTHOR]

Abstract: Thin films of ITO distinguished by an accessible uniform mesoporosity providing an unhindered access to well-defined inner surface, high transparency and good electrical conductivity were prepared by a template-assisted synthesis procedure. Indium acetylacetonate serving as the source of indium oxide made it possible to slow down the crystallization of indium oxide as compared to inorganic salt precursors. The preparation procedure included the following steps: (1) slow condensation step at 100–300 ∘C in air, providing the amorphous ITO precursor with a high level of 3D-organization around the template micelles; (2) treatment in air at 450–550 ∘C necessary for the removal of the template and opening the mesoporosity; (3) treatment in nitrogen at 450 ∘C required for the improvement of the film’s conductivity. [Copyright &y& Elsevier]

Innovative strategies to produce well-defined nanoparticles and other nanostructures such as nanofibres, quantum wells and mesoporous materials have revitalized materials science for the potential benefit to society. Here, we report a controlled process, involving soft-chemistry-based deposition, template-assisted mesostructured growth, and tuned annealing conditions that allows the preparation of ordered mesoporous crystalline networks and mesostructured nano-island single layers, composed of multicationic metal oxides having perovskite, tetragonal or ilmenite structures. This strategy to obtain meso-organized multi-metal-oxide nanocrystalline films (M3NF) bridges the gap between conventional mesoporous materials and the remarkable properties of crystalline ternary or quaternary metallic oxides. Nanocrystalline mesoporous films with controlled wall thickness (10–20 nm) of dielectric SrTiO3, photoactive MgTa2O6 or ferromagnetic semi-conducting CoxTi1−xO2−x were prepared by evaporation-induced self-assembly (EISA) using a specially designed non-ionic block-copolymer template. A tuned thermal treatment of the mesoporous films permits the transfer of the wall structure into nanocrystallites, with all tectonic units being tightly incorporated into mechanically stable ordered tri- or bidimensional nanocrystalline networks. This methodology should allow multifunctionalization, miniaturization and integration during development of devices such as smart sensors and actuators, better-performing photocatalysts, and fast electrochromic devices. On the other hand, organized arrays of dispersed ferromagnetic or ferroelectric nanoparticles are promising materials for spintronics and for cheap, non-volatile 'flash' memories. [ABSTRACT FROM AUTHOR]

The solid-state structures of polystyrene–poly(Z-l-lysine) block copolymers were examined with respect to the polymer architecture and the secondary structure of the polypeptide using circular dichroism, quantitative small- and wide-angle X-ray scattering, and electron microscopy. Linear block copolymers exhibit a hexagonal-in-lamellar structure where folded and packed polypeptide α-helices form lamellae which extend over an exceptional broad range of the composition diagram. Star- or bottlebrush-shaped copolymers are able to stabilize a larger interface area than linear ones which promotes the formation of undulated lamellar mesophases. Depending on the secondary structure of polypeptide segments, plane lamellar, superundulated lamellar, or corrugated lamellar phases are formed. These results indicate the importance of a secondary structure and packing of polymer chains for the formation of new phases and ordering far from the ‘classical’ phase behavior. [Copyright &y& Elsevier]

Even after centuries-old experience in carbonizing materials we can still learn new lessons and find new applications for carbonized materials. In the past decades, laser-assisted syntheses of materials have emerged as versatile tools for the fabrication of micro- and nanostructured functional devices. In this regard, laser-carbonization is of particular interest, as it provides a method for patterning eco-friendly and potentially biodegradable electronic materials for future applications in comparison to the state-of-the-art in flexible electronics. However, using molecular precursors for laser-carbonization has been a challenge for many years. We identified a set of three different precursors and conducted an in-depth morphological and compositional study to understand how molecular precursors must be prepared for the high-speed carbonization reactions used in laser-patterning. The resulting laser-patterned carbons (LP-C) or N-doped carbons (LP-NC) are different from their conventionally pyrolyzed reference products mostly in terms of morphology. A generally porous structure and a carbonization gradient induced by the top-to-bottom energy input are the most remarkable features. Additionally, the microstructure, the elemental composition and the resulting electronic properties are different as demonstrated by X-ray photoelectron spectroscopy (XPS) and wide-angle X-ray scattering (WAXS) analysis. [Display omitted] [ABSTRACT FROM AUTHOR]

Halloysite nanotubes (HNTs) have been treated with piranha solution, in order to activate their surface and enable a higher grafting of aminopropyl silane and, in turn, a higher loading of Au nanoparticles. The resulting nanocomposites display better performance, in terms of stability and activity, for both reduction and oxidation reactions, than the non-treated HNTs. • HNTs etching with piranha solution increases the surface area and Au nanoparticles loading. • The increased amount of amino propyl groups on HNTs stabilizes positively charged Au nanoparticles. • The etched heterogeneous catalyst performs better for both reduction and oxidation. Halloysite nanotubes (HNTs) can be conveniently used as scaffolds to load catalytic units, to enable efficient heterogeneous catalytic processes. In this contribution, we report a facile strategy to prepare a composite system based on Au nanoparticles (NPs) supported on piranha-etched HNTs. The resulting nano-system was characterized by FTIR, XPS and nitrogen physisorption to highlight its surface properties and porosity. Compared to the non-treated reference HNTs, the increase of hydroxyl groups on the etched HNTs walls allowed to graft a double amount of 3-aminopropyl silane (5.7 wt% vs. 2.8 wt%) and, consequently, to load 15.5 wt% more gold NPs. On the other hand, the interaction of the amino groups with Au NPs stabilizes positively charged NPs, thus leading to excellent catalytic activity and stability. The resulting nano-hybrid can catalyse the reduction of 4-nitrophenol to 4-aminophenol with a kinetic rate constant 53% higher than the reference reaction. In addition, it can be reused for 8 times without significant loss of activity. The supported system also demonstrates its potential in the oxidation of a sugar-derived molecule, i.e., furfural, which is converted into furoic acid with turnover frequency (TOF) 25% higher than the reference. [ABSTRACT FROM AUTHOR]

A new derivative of the ligand (2‐aminoethyl)bis(2‐pyridylmethyl)amine (uns‐penp), capable for covalent immobilization on silica, was synthesized. Silica powder for column chromatography and mesoporous monoliths served as surface material. Functionalized silica was sufficiently characterized with reflectance UV/Vis and FTIR techniques. Copper(I) was successfully complexed with the immobilized ligand and exhibits reversible reactivity towards dioxygen at low temperatures. Suspending the oxygen species with toluene at low temperatures led to selective oxygenation to benzaldehyde, determined by GC‐MS. Copper(I) complexes with the ligands Me‐PTS‐uns‐penp and Me‐Prop‐uns‐penp were prepared and characterized to model the reaction behavior towards dioxygen in solution. Additionally, solid copper peroxido complexes with these ligands were obtained by precipitation with the sterically demanding anion tetraphenylborate. Furthermore, these complexes could be obtained in a reversible reaction by treating corresponding copper(I) complexes with dioxygen. With all oxygenated copper complexes catalytic oxidation of toluene was observed. [ABSTRACT FROM AUTHOR]

The preparation of carbons for technical applications is typically based on a treatment of a precursor, which is transformed into the carbon phase with the desired structural properties. During such treatment the material passes through several different structural stages, for example, starting from precursor molecules via an amorphous phase into crystalline-like phases. While the structure of non-graphitic and graphitic carbon has been well studied, the transformation stages from molecular to amorphous and non-graphitic carbon are still not fully understood. Disordered carbon often contains a mixture of sp3-, sp2-and sp1-hybridized bonds, whose analysis is difficult to interpret. We systematically address this issue by studying the transformation of purely sp3-hybridized carbons, that is, nanodiamond and adamantane, into sp2-hybridized non-graphitic and graphitic carbon. The precursor materials are thermally treated at different temperatures and the transformation stages are monitored. We employ Raman spectroscopy, WAXS and TEM to characterize the structural changes. We correlate the intensities and positions of the Raman bands with the lateral crystallite size L a estimated by WAXS analysis. The behavior of the D and G Raman bands characteristic for sp2-type material formed by transforming the sp3-hybridized precursors into non-graphitic and graphitic carbon agrees well with that observed using sp2-structured precursors. Image 1 [ABSTRACT FROM AUTHOR]

The influence of the cation of imidazolium‐derived ionic liquids (ILs) on a low‐temperature solution‐based synthesis of hexagonal tungsten bronze (HTB) type Ti(OH)OF ⋅ 0.66 H2O and bronze‐type TiO2(B) is investigated. The IL (Cxmim BF4) acts as solvent and also as reaction partner with respect to the decomposition of [BF4]−, releasing F−. In the present study, the chain length of the alkyl chain side groups attached to the imidazolium ring was varied (C2mim BF4 to C10mim BF4), and the obtained solids were analyzed by Powder X‐Ray diffraction (PXRD) followed by Rietveld refinement. As a main finding these analyses indicate a transformation of Ti(OH)OF ⋅ 0.66 H2O into TiO2(B), and upon prolonged reaction time finally also into anatase TiO2. Rietveld analysis suggests that when using ILs with longer alkyl chains, the conversion of Ti(OH)OF ⋅ 0.66 H2O is slower compared to syntheses performed with smaller alkyl chains. Hence, Ti(OH)OF ⋅ 0.66 H2O appears to be metastable and is stabilized by long‐chain ILs serving as surfactant attached to the crystallites' surface. In this view, the ILs shield the nanoparticles and thus slow down the conversion into the more stable compounds. This confirms previous findings that ILs act as both, solvent and reaction medium in this reaction, thus enabling the synthesis of peculiar Ti‐oxides. [ABSTRACT FROM AUTHOR]

Deactivation of CeO2‐based catalysts in the HCl oxidation reaction proceeds via selective bulk chlorination of the active CeO2 component to form CeCl3×nH2O. We study the reactivation of two bulk‐chlorinated CeO2‐based Deacon catalysts by oxygen treatment at 430 °C, namely pure CeO2 and 20 mol % of CeO2 supported on preformed ZrO2 particles (20CeO2@ZrO2), with a dedicated experiment. In the flow reactor setup we determine in‐situ the degree of chlorination of the catalyst by quantifying down‐stream with in‐situ UV‐Vis spectroscopy the total amount of chlorine in the catalyst that is exchanged by reoxidation at 430 °C. The activity of deactivated 20CeO2@ZrO2 can be fully restored by oxygen exposure at 430 °C, while that of pure CeO2 declines steadily. Since the UV‐Vis analytics is fast and sensitive, we can follow the kinetics of reoxidation. To rationalize the observed kinetics, we develop a modified Johnson‐Mehl‐Avrami‐Kolmogorov (JMAK) model based on a nucleation‐and‐growth approach for the reoxidation of the catalyst starting from the chlorinated phase. The fast reoxidation kinetics of chlorinated 20CeO2@ZrO2 is traced to a fast nucleation rate. [ABSTRACT FROM AUTHOR]

Carbon aerogels find application in many fields. In most of the applications, they are used as powders and thus need to be pulverized. However, the pulverization could induce various changes in the microstructure of carbon aerogels. The extent of changes depends not only on the dominant forces of used technique, but also on the mechanical and structural properties of initial monolithic samples. In the present work, we discuss the influence of grinding, milling in shaker cryo-mill, and planetary ball mill on stiff, ductile and flexible carbon aerogels. Scanning electron microscopy and transmission electron microscopy images, gas sorption techniques, wide-angle X-ray scattering, and Raman spectroscopy show a strong dependency of the introduced energy amount while pulverization on the structure modification. Results show that stiff carbon aerogels do not undergo noticeable changes. In contrast, ductile carbon aerogels are very sensitive to friction forces. Soft and flexible carbon aerogels undergo drastic changes in the microstructure. [ABSTRACT FROM AUTHOR]

We study the transformation from molecular to crystalline of (non-)graphitic carbons synthesized from organic precursors by heat-treatment. Easy assessment of structural properties resulting from heat-treatment protocols is mandatory for industrial process monitoring. We demonstrate that Raman spectroscopy, in particular, the Raman lineshape analysis of G and D mode, offers quick assessment of the average sheet size of such carbons. We validate this method by performing Raman, WAXS and EPR measurements of series of resin and pitch-based carbons synthesized. The crystallite sizes of the WAXS analysis for the individual samples are related to corresponding positions and linewidths of G and D Raman modes and show excellent agreement between experiment and modelling from large sizes down to 4 nm. The theoretical master curves are independent of the precursor used in the synthesis, in contrast to models for the intensity ratio of D and G band versus size. We show that the latter are not universally valid and differ for each class of precursors. For sizes below 4 nm, our lineshape model fails as it is based on the bandstructure and phonon dispersions of ideal graphene. Thus, 4 nm corresponds to the fundamental transition from molecular to crystalline character for non-graphitic carbons. Image 1 [ABSTRACT FROM AUTHOR]

In this work a facile ionic liquid-based synthesis towards titanium oxyhydroxyfluoride Ti(OH)OF is presented. The synthesis is carried out as a one-pot synthesis at a relatively low temperature (95 °C). The ionic liquids are used as both the reaction medium and fluorination source. Powder X-ray diffraction (PXRD) followed by Rietveld refinement revealed a hexagonal crystal structure similar to the hexagonal tungsten bronze (HTB) structure known in the literature. We also show that water is present inside the channels of the crystal structure. Additionally, we performed transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS) and thermogravimetric analysis coupled with mass spectrometry (TGA-MS) measurements. The results of the different methods are in agreement with the HTB-Ti(OH)OF structure. In addition to the structural analysis, the electrochemical performance of the material was studied by measuring galvanostatic charge/discharge profiles and cyclic voltammetry using Li+. We found a rather high specific capacity in the range above 200 mA h g−1 (at 0.1 A g−1) and an excellent rate capability (more than 110 mA h g−1 at 5 A g−1), which makes this material a promising material for future electrochemical applications (e.g. batteries). [ABSTRACT FROM AUTHOR]

Nanostructured ZnO particles were prepared through a straightforward, quick and low‐temperature synthesis route involving coprecipitation of the metal precursor salts with oxalic acid, followed by hydrothermal treatment at 135 or 160 °C. The synthesised nanostructured powders were thoroughly characterised by a wide array of analytical techniques from the morphological (Scanning Electron Microscopy ‐SEM‐, Transmission Electron Microscopy ‐TEM‐, Energy‐dispersive X‐ray Spectroscopy ‐EDXS‐), structural (Powder X‐ray Diffraction ‐PXRD‐, Selected Area Electron Diffraction ‐SAED‐), compositional (X‐ray Photoelectron Spectroscopy ‐XPS‐) and physical (thermal stability) point of view. As far as functional applications are concerned, the powders were tested as gas sensor materials for H2S detection. Thereby these ZnO particles showed unexpected gas dosimeter behaviour at 150 °C. Based on these observations and on a comparison with literature a new model for the interaction of ZnO nanostructures with H2S is proposed. Nanostructured ZnO was synthesised through a quick, easy, low‐temperature and green hydrothermal route, showing an interesting gas‐sensing behaviour. At an operation temperature of 450 °C, the material exhibits a significant response to H2S gas exposure as expected for a semiconducting n‐type gas sensor. However, at an operating temperature of 150 °C the material shows gas dosimeter‐type behaviour. [ABSTRACT FROM AUTHOR]

Sr3Fe2WO9 and Ba3Fe2WO9 triple perovskites have been prepared in nanocrystalline form using a modified sol–gel route with citric acid as a chelating agent. These materials have been studied by X-ray powder diffraction (PXRD), energy-dispersive X-ray (EDX) spectroscopy, transmission electron microscopy (TEM), scanning electron microscopy (SEM), and unpolarized Raman spectroscopy, while their magnetic properties have been determined using SQUID measurements. At room temperature, the crystal structure of 6H-perovskite Ba3Fe2WO9 is hexagonal, space group P63/mmc, with a = 5.7577(2) and c = 14.1095(5) Å, whereas Sr3Fe2WO9 presents a tetragonal lattice, space group I4/m, with a = 5.5803(1) and c = 7.8745(3) Å. Both compounds are nanocrystalline with average crystallite sizes of 25.6(1) nm for Ba3Fe2WO9 and 35.9(1) nm for Sr3Fe2WO9 with moderate microstrain. They exhibit a disordered perovskite structure, in which Fe3+ and W6+ cations distribute randomly at the B-sites of the perovskite lattice: Sr2[Fe0.72W0.28]2a[Fe0.61W0.39]2bO6 and Ba6[Fe1.71W0.29]2a[Fe2.29W1.71]4fO18. The detected hysteresis loops with non-zero remanent magnetization and a rather large coercive field reveal ferrimagnetic ordering with ordering temperatures of 373 K for Sr3Fe2WO9 and 330 K for Ba3Fe2WO9. Magnetic measurements show the onset of ferrimagnetic ordering at relatively high temperatures of 717 and 711 K for the Sr and Ba compounds, respectively; however the magnetization isotherms at 2 K exhibit, for H = 50 kOe, maximum magnetization values close to 0.8 μB (f.u.)−1 and 0.35 μB (f.u.)−1 for Sr and Ba compounds, respectively, although full saturation is not reached. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • Mixed Ce 1-x Zr x O 2 nano-rods are active in the Deacon process at 430 °C. • Chlorine is incorporated in the surface-near region of Ce 1-x Zr x O 2 nano-rods: active phase. • The stability of Ce 1-x Zr x O 2 nano-rods depend strongly on the Zr-concentration. • Thermodynamic modelling of Zr-induced stabilization of Ce 1-x Zr x O 2 nano-rods. Abstract Mixed Ce 1-x Zr x O 2 nano-rod particles with varying Zr doping levels of up to 20% were exposed to Deacon reaction mixtures with high HCl concentration at a reaction temperature of 430 °C. The mixed Ce 1-x Zr x O 2 nano-rod samples were characterized before and after Deacon reaction by x-ray diffraction (XRD), transmission electron microscopy (TEM), and x-ray photoelectron spectroscopy (XPS). Pure CeO 2 nano-rods are shown to suffer from bulk-chlorination of the catalyst (CeCl 3 x6H 2 O) for reaction mixtures HCl:O 2 > 2 that is accompanied by dramatic activity losses. For a reaction mixture of HCl:O 2 = 2.5:1, already 5% Zr doping suffices to stabilize the structure Ce 1-x Zr x O 2 nano-rods against bulk chlorination. Although ZrCl 4 is volatile above 330 °C, we do not encounter discharge of Zr from the fixed bed flow reactor as long as severe bulk chlorination of the Ce 1-x Zr x O 2 catalysts in the form of CeCl 3 is not observed in XRD. With a simple quasi steady-state model we can corroborate the stabilizing effect of Zr assuming that ZrCl 4 evaporation is limited by diffusion of Zr4+ in the ceria-zirconia subsurface. As qunatified with XPS the chlorine concentration of stable and active Ce 1-x Zr x O 2 nano-rods with 5% Zr is too high to be solely ascribed to on-surface chlorine. The incorporation of Cl into the surface-near region is further supported by XPS experiments performed after oxygen plasma treatment. For even more harsh reaction conditions HCl:O 2 = 3:1 none of the Ce 1-x Zr x O 2 nano-rods was stable at 430 °C. However, an increase of the reaction temperature to 500 °C enables even pure CeO 2 nano-rods to be stable under such harsh reaction conditions. [ABSTRACT FROM AUTHOR]

We pyrolyzed and activated novolac beads in one single step with ammonia at different temperatures (750–950 °C), which leads to a highly porous carbon with nitrogen-doping. The chemical and physical properties were characterized and correlated with the electrochemical performance as supercapacitor electrodes. The average pore size varied at 0.6–1.4 nm dependent on the synthesis temperatures. Three different electrolytes (aqueous, organic, and an ionic liquid) were tested. The specific capacitance in a symmetrical supercapacitor reached up to 173 F g −1 and was strongly dependent on the porosity of the electrode material and the kind of electrolyte. We found that the presence of nitrogen enhanced the electrochemical performance stability and led to a high specific energy of 50 Wh·kg −1 using an ionic liquid as electrolyte. [ABSTRACT FROM AUTHOR]

MFe2O4 spinel ferrites (M = Co, Mn, Ni, Zn) were synthesised through a low-temperature aqueous route combining co-precipitation of oxalates and hydrothermal treatment at 135 °C. With the objective of gaining a deeper understanding of the structural evolution of the compounds to crystalline materials during the synthetic process, samples were prepared within different reaction times, showing in most cases a fully crystalline habit already after short treatment times. The resulting solids were characterised through several state-of-the-art analytical techniques, both on the atomic (XAS) and mesoscopic (XRPD, SAXS) scales. In parallel, temperature-programmed characterisation was carried out to investigate the evolution of the compounds during the heating process. [ABSTRACT FROM AUTHOR]

Abstract: Poly(divinylbenzene) (PDVB) nanofibers are synthesized by electrospinning dispersions of PDVB nanoparticles (diameter 40–90 nm) derived by miniemulsion polymerization. Interparticle crosslinking is achieved by addition of a radical starter after electrospinning endowing the fibers with high solvent‐stability. The fibers exhibit a Brunauer–Emmett–Teller (BET) surface area in the range of ≈30–70 m2 g−1 due to internal mesoporosity, which originates from the interparticle space. Spinning parameters like the concentrations of spin polymer and nanoparticles, as well as the nanoparticle diameter, are systematically varied to investigate the influence of these parameters on the mesopore structure. The fiber morphology is studied by scanning electron microscopy and the mesopore size, volume, and BET surface area are determined by nitrogen physisorption measurements. The findings indicate that the pore size mainly depends on the PDVB nanoparticle diameter. As a main finding, the fiber diameter can be adjusted by the concentration of spin polymer or nanoparticles without changing the mesopore diameter. Chlorine‐functionalized fibers are synthesized by electrospinning of poly(divinylbenzene‐co‐4‐vinylbenzyl chloride) nanoparticle dispersions. Chlorine groups are further used for the covalent immobilization of an organocatalyst (2,2,6,6‐tetramethylpiperidine‐1‐oxyl (TEMPO)). [ABSTRACT FROM AUTHOR]

Temporary storage of oxygen in a solid catalyst is imperative for many important industrial oxidation reactions in the gas phase, for instance the post-treatment of automotive exhaust gas. A peculiar mixed Ce-Zr (1:1) oxide, the ordered κ-Ce2Zr2O8 phase, is a promising catalytic material exhibiting an extraordinarily high oxygen storage capacity (OSC) and high thermal and chemical stability. We elucidate the temperature-dependent transformation between the pyrochlore pyr-Ce2Zr2O7 and κ-Ce2Zr2O8 phase upon oxygen uptake by in situ X-ray diffraction, X-ray absorption, and in situ Raman spectroscopy, providing insights into the electronic and structural changes on the atomic level, which are at the heart of the extraordinarily high OSC. We demonstrate that the Ce3+ concentration can be followed during transformation in situ by Raman spectroscopy of the electronic spin flip in the f-shell of Ce3+. The catalytic activity of the κ-Ce2Zr2O8 phase was investigated without an additional active component such as noble metals (Pt, etc.). While the high OSC of the κ-phase is beneficial for the oxidation of CO, the oxidation of HCl turns out to be unaffected by the high OSC. [ABSTRACT FROM AUTHOR]

In this work, we present detailed investigations on the influence of binary ionic liquid (IL) mixtures on sol-gel syntheses of metastable metal oxide phases. The synthesis of the metastable TiO2 bronze phase and anatase as well as the rutile modification is followed via in situ diffraction methods coupled with thermal gravimetric analysis. The variation of the composition of mixtures of ILs allows for the adjustment of TiO2 phase composition at low temperatures. On the basis of these results, the synthesis of the hexagonal tungsten bronze-like titanium hydroxyl oxy fluoride was achieved. Our results pave the way for a deeper understanding of IL participation in the syntheses of inorganic nanomaterials, going further than treating them as solvents. [ABSTRACT FROM AUTHOR]