Black goes green: single-step solvent exchange for sol-gel synthesis of carbon spherogels as high-performance supercapacitor electrodes.

Nanoporous carbon materials with customized structural features enable sustainable and electrochemical applications through improved performance and efficiency. Carbon spherogels (highly porous carbon aerogel materials consisting of an assembly of hollow carbon nanosphere units with uniform diameters) are desirable candidates as they combine exceptional electrical conductivity, bespoke shell porosity, tunability of the shell thickness, and a high surface area. Herein, we introduce a novel and more environmentally friendly sol-gel synthesis of resorcinol-formaldehyde (RF) templated by polystyrene spheres, forming carbon spherogels in an organic solvent.

Tannin-Based Nanoscale Carbon Spherogels as Electrodes for Electrochemical Applications.

A promising route to monolithic, hollow sphere carbon assemblies based on sustainable precursors with a tailored nanostructure is presented. These carbon assemblies, recently termed carbon spherogels, are generated via a polystyrene sphere template-based sol-gel process of mimosa tannin and biomass-derived 5-(hydroxymethyl)furfural. By completely replacing petroleum-based precursors (especially toxic formaldehyde) highly porous, nanoscale carbon monoliths are obtained, which are investigated as state-of-the-art, sustainable electrode materials for energy storage.

Development of foam-like emulsion phases in porous media flow.

Hypothesis: While surfactant solutions mobilize residual oil under optimal conditions by lowering the water-oil interfacial tension, emulsion phases outside of the optimum tend to be immobile. How are mobility and texture of such phases related, and how can the stability of these phases be understood? Can non-optimized surfactant solutions improve displacement processes through mobility control?

Experiment: Emulsification and miscibility during surfactant flooding were investigated in microfluidics with generic oil and surfactant solutions. The salt concentration was varied in an exceptionally wide range across the optimal displacement conditions.

Hybrid carbon spherogels: carbon encapsulation of nano-titania.

Extraordinarily homogeneous, freestanding titania-loaded carbon spherogels can be obtained using Ti(acac)(OiPr) in the polystyrene sphere templated resorcinol-formaldehyde gelation. Thereby, a distinct, crystalline titania layer is achieved inside every hollow sphere building unit. These hybrid carbon spherogels allow capitalizing on carbon's electrical conductivity and the lithium-ion intercalation capacity of titania.

A new device for high-temperature in situ GISAXS measurements.

A heating stage originally designed for diffraction experiments is implemented into a Bruker NANOSTAR instrument for in situ grazing incidence small-angle x-ray scattering experiments. A controlled atmosphere is provided by a dome separating the sample environment from the evacuated scattering instrument. This dome is double shelled in order to enable cooling water to flow through it.

Biological fabrication of cellulose fibers with tailored properties.

Cotton is a promising basis for wearable smart textiles. Current approaches that rely on fiber coatings suffer from function loss during wear. We present an approach that allows biological incorporation of exogenous molecules into cotton fibers to tailor the material's functionality.

Pore shape and sorption behaviour in mesoporous ordered silica films.

Mesoporous silica films templated by pluronic P123 were prepared using spin and dip coating. The ordered cylindrical structure within the films deforms due to shrinkage during calcination. Grazing-incidence small-angle X-ray scattering (GISAXS) measurements reveal that both the unit cell and the cross section of the pores decrease in size, mainly normal to the surface of the substrate, leading to elliptical cross sections of the pores with axis ratios of about 1:2.

Passive and active mechanical properties of biotemplated ceramics revisited.

Living nature and human technology apply different principles to create hard, strong and tough materials. In this review, we compare and discuss prominent aspects of these alternative strategies, and demonstrate for selected examples that nanoscale-precision biotemplating is able to produce uncommon mechanical properties as well as actuating behavior, resembling to some extent the properties of the original natural templates. We present and discuss mechanical testing data showing for the first time that nanometer-precision biotemplating can lead to porous ceramic materials with deformation characteristics commonly associated with either biological or highly advanced technical materials.

Cantilever bending based on humidity-actuated mesoporous silica/silicon bilayers.

We use a soft templating approach in combination with evaporation induced self-assembly to prepare mesoporous films containing cylindrical pores with elliptical cross-section on an ordered pore lattice. The film is deposited on silicon-based commercial atomic force microscope (AFM) cantilevers using dip coating. This bilayer cantilever is mounted in a humidity controlled AFM, and its deflection is measured as a function of relative humidity.

Moisture-Driven Ceramic Bilayer Actuators from a Biotemplating Approach.

The former ovuliferous scales of biotemplated cones of Pinus nigra show moisture-driven actuation similar to their biological templates, demonstrating a facile route to obtain ceramic moisture-sensitive bilayer actuators. Based on comparative analysis of their hierarchical nanometer-precision replica structures, using, e.g.

Random Lasing with Systematic Threshold Behavior in Films of CdSe/CdS Core/Thick-Shell Colloidal Quantum Dots.

While over the past years the syntheses of colloidal quantum dots (CQDs) with core/shell structures were continuously improved to obtain highly efficient emission, it has remained a challenge to use them as active materials in laser devices. Here, we report random lasing at room temperature in films of CdSe/CdS CQDs with different core/shell band alignments and extra thick shells. Even though the lasing process is based on random scattering, we find systematic dependencies of the laser thresholds on morphology and laser spot size.

Crystal Phase Transitions in the Shell of PbS/CdS Core/Shell Nanocrystals Influences Photoluminescence Intensity.

We reveal the existence of two different crystalline phases, i.e., the metastable and the equilibrium phase within the CdS-shell of PbS/CdS core/shell nanocrystals formed by cationic exchange.

Transparent cellulose sheets as synthesis matrices for inorganic functional particles.

Transparent cellulose sheets were prepared through tape-casting a solution of cellulose. Flexible, luminescent sheets were produced by adding europium trichloride to the casting solution and treating the sheets with an aqueous solution of ammonium fluoride. Scanning electron micrographs of the resulting sheets showed europium trifluoride particles with diameters from 200nm to 500nm.

Dilution induced thickening in hydrotrope-rich rod-like micelles.

Dilution induced changes in the microstructure and rheological behavior of micelles formed by a cationic surfactant-anionic hydrotrope mixture has been investigated in the hydrotrope-rich region. The surfactant used is cetyltrimethylammonium bromide (CTAB) and the hydrotropic salt is sodium 3-hydroxy naphthalene 2-carboxylate (SHNC). The concentration of the mixture is varied from 0.

Infrared emitting and photoconducting colloidal silver chalcogenide nanocrystal quantum dots from a silylamide-promoted synthesis.

Here, we present a hot injection synthesis of colloidal Ag chalcogenide nanocrystals (Ag(2)Se, Ag(2)Te, and Ag(2)S) that resulted in exceptionally small nanocrystal sizes in the range between 2 and 4 nm. Ag chalcogenide nanocrystals exhibit band gap energies within the near-infrared spectral region, making these materials promising as environmentally benign alternatives to established infrared active nanocrystals containing toxic metals such as Hg, Cd, and Pb. We present Ag(2)Se nanocrystals in detail, giving size-tunable luminescence with quantum yields above 1.

Real space functions from experimental small angle scattering data.

A model free evaluation of small angle scattering data of interacting particles results in real space curves that are often difficult to interpret. It is then easier to use a model for the inter and/or the intra particle effects. Such a procedure requires the selection of appropriate models.

Large-area ordered superlattices from magnetic Wustite/cobalt ferrite core/shell nanocrystals by doctor blade casting.

Although a large diversity of single-component and binary superlattices from colloidal nanocrystals have been demonstrated, applications of such ordered nanocrystal assemblies are still hampered due to a lack of control over the self-assembly processes over large areas. A reel-to-reel compatible large-area coating technique for solutions is given by doctor blade casting, which is applied here to deposit colloidal nanocrystals onto various substrates. The self-assembly process is demonstrated for magnetic nanocrystals, having a high potential for applications in magnetic memory devices.

Exploring the structural properties of simple aldehydes: a Monte Carlo and small-angle X-ray scattering study.

The structure of simple linear alkanals from propanal to nonanal was studied utilizing configurational bias Monte Carlo (MC) simulations of the aldehydes modeled according to the transferable potential for phase equilibria-united atom force field (TraPPE-UA) and was compared to experimental small-angle X-ray scattering (SAXS) results. This was done by exploiting a recently developed approach for calculating the scattering intensities from theoretically obtained MC data by utilizing the Debye equation (Tomsic et al. J.

Structural characterization of nonionic mixed micelles formed by C12EO6 surfactant and P123 triblock copolymer.

A structural characterization of mixed micelles formed in aqueous solution by the PEO-PPO-PEO triblock copolymer P123 and the nonionic surfactant C(12)EO(6) was carried out using various techniques, including ultralow shear viscosimetry, depolarized dynamic light scattering (VH-DLS), depolarized static light scattering (VH-SLS), and small-angle X-ray scattering (SAXS). The sphere-to-rod transition of the mixed micelles was studied in a diluted regime (P123 concentrations ranging from 0.5 to 10 wt %) at C(12)EO(6)/P123 molar ratios of 2.