AbstractContinuous-flow biocatalysis utilizing immobilized enzymes emerged as a sustainable route for chemical synthesis. However, inadequate biocatalytic efficiency from current flow reactors, caused by non-productive enzyme immobilization or enzyme-carrier mismatches in size, hampers its widespread application. Here, we demonstrate a general-applicable and robust approach for the fabrication of a high-performance enzymatic continuous-flow reactor via integrating well-designed scalable isoporous block copolymer (BCP) membranes as carriers with an oriented and productive immobilization employing material binding peptides (MBP). Densely packed uniform enzyme-matched nanochannels of well-designed BCP membranes endow the desired nanoconfined environments towards a productive immobilized phytase. Tuning nanochannel properties can further regulate the complex reaction process and fortify the catalytic performance. The synergistic design of enzyme-matched carriers and efficient enzyme immobilization empowers an excellent catalytic performance with >1 month operational stability, superior productivity, and a high space-time yield (1.05 × 105 g L−1 d−1) via a single-pass continuous-flow process. The obtained performance makes the designed nano- and isoporous block copolymer membrane reactor highly attractive for industrial applications.

Air Springs are deployed in many technical areas today. In the premium segment of the automotive industry in particular, they are being used more and more frequently. The load-independent spring rate results in a better ride comfort. Since the stiffness of the Air Spring is significantly influenced by the enclosed air volume, this usually leads to a conflict of objectives between the available installation space and the stiffness optimum. To reduce the spring stiffness while maintaining the same design space, Coackley and Elliot describe in their patent the use of adsorbents such as activated carbon in the enclosed air volume of the spring. By binding air molecules to the adsorbent, more air molecules fit into the enclosed Air Spring volume, while the size and pressure of the Air Spring remain the same. This paper describes how the so-called “virtual volume” is created by adsorption and how it can be determined by simplified measurements using a gas pycnometer. Furthermore, it is shown how these measurements are related to the static stiffness of an Air Spring, so that a prediction of the static stiffness of an Air Spring filled with sorbent, in this case activated carbon, is possible by simple pycnometric measurements.

This paper illustrates the gas adsorption properties of newly synthesized nanoporous cross-linked polymer networks (CPNs). All synthesized CPNs possess N-rich functional groups and are used for the utilization of carbon dioxide and methane. Good gas adsorption and selectivities are obtained for all of the samples. Among the materials, HEREON2 outperforms better selectivity for methane separation from nitrogen rather than zeolites, activated carbons, molecular sieves, covalent organic frameworks, and metal-organic frameworks (MOFs). The accessibility of the N-rich functionalities makes these materials potential candidates for the separation of hydrocarbons via increased polarizabilities. High-pressure adsorption experiments showed that the synthesized two-dimensional nanoporous materials also have a high affinity toward carbon dioxide. HEREON2 powders showed an increased experimental CO2/N2 selectivity of ∼25,000 at 50 bar due to the presence of nitrogen groups in the structure. Fourier-transform infrared spectroscopy (FTIR), solid-state NMR, X-ray diffraction, thermogravimetric analysis, energy-dispersive X-ray spectroscopy (EDX), transmission electron microscopy (TEM), and scanning electron microscopy (SEM) were applied for the characterization of the synthesized nanoporous CPNs. The results show a potential new pathway for future CPN membrane development.

Bismuth vanadate (BiVO 4 ) offers high photon efficiencies in solar photo-anodes, due to its suitable semiconductor band gap energies and associated visible light absorption. In well-tuned conditions, such anodes enable green hydrogen generation in photoelectrochemical water splitting cells. Bismuth vanadate films have to ensure high efficiencies in electron/hole pair generation and sufficiently high rates of charge transfer to the conducting substrate and the electrolyte, respectively. Thus, the tuning of coating properties has to aim for high phase purity, good layer integrity as well as optimum diffusion path lengths. In order to explore the potential of aerosol deposition to produce BiVO 4 films with high photoelectrochemical activity and to elucidate influences on microstructure and application properties, powder sizes and spraying parameters had to be tailored. By ball milling over durations of up to 20 min, particles sizes in the range from 8.3 down to 0.6 µm were obtained. With respect to spray conditions, the process gas pressure was varied from 1.0 to 2.1 bar corresponding to gas flow rates of 10-40 l/min. The wide range of powder sizes and parameters in aerosol deposition allowed for developing a window of deposition in order to derive the most promising combinations for layer build-up. Optimum parameter sets in application on stainless steel substrates were transferred to FTO-coated glass substrates for backlit cell layouts. The thickness and conductivity of the layers were adjusted to a layer thickness range of 200-500 nm in order to achieve maximum photocurrents. The production of homogeneous, large-scale prototypes demonstrates that aerosol deposition is suitable for processing layers for solar energy harvesting with high photo current densities of up to 3.55 mA/cm 2 .

Due to its suitable semiconductor band gap energies and associated visible light absorption, bismuth vanadate offers high photon efficiencies in solar photo-anodes, enabling green hydrogen generation in photoelectrochemical water splitting cells. Respective bismuth vanadate films have to ensure high efficiencies in electron / hole pair generation, and sufficiently high rates of charge transfer, for both, electrons to the conducting substrate, as well as holes to the electrolyte. Thus, tuning of coating properties has to aim for high phase purity and good layer integrity. So far, respective films are mainly produced by thin film techniques, but at rather high costs and low deposition rates. Less costly processing routes are opened by thermal spraying or sol-gel techniques, however, these cannot guarantee the required phase purity or absence of remnants from the binder. As solid state and binderless alternative, Aerosol Deposition (AD) offers several advantages: comparative low costs, high deposition rates, no undesired phase transformations, and no impurities or residues that could reduce the photoelectrochemical activity. Under the scope of this research on photo-electrochemically active bismuth vanadate films, powder sizes were tailored by milling, and spray parameter sets like the process gas pressure were varied, in order to elucidate their influence on microstructure and application properties. Covering a wide parameter range in aerosol deposition allowed for the development of a window of deposition. Most promising combinations for layer build-up were derived. The results on stainless steel substrates were transferred to FTO-coated glass substrates, as needed in backlit cell layouts. For fine tuning of maximum photocurrents, layer thickness and conductivity were then systematically adjusted. Homogeneous large-scale prototypes demonstrate that aerosol deposition is suitable for processing layers for solar energy harvesting.

Crystallization of poly(phenylene sulfone) (PPSU) occurs given that the solvent quality is low. This may be the case through adding a nonsolvent to a good solvent like N-methyl-2-pyrrolidone (NMP) or by choosing a poor solvent like N,N'-dimethylacetamide (DMAc) or N,N'-dimethylformamide (DMF). Wide-angle X-ray scattering (WAXS) investigations revealed the degree of crystallinity of PPSU in DMF and DMAc, and the lattice spacing for the structures was calculated to be 5.30 and 5.24 angstrom, respectively. Poly(phenylene sulfone) in DMAc formed well-defined banded spherulites with typical maltese crosses as observed by polarized light microscopy. For PPSU in DMF, crystalline plates were found by means of atomic force microscopy (AFM) with a thickness of 21 nm for a single plate. Both structures consist of lamellar fibrils with a thickness of 10 nm and a length in the order of 100-150 nm. The authors propose the reason for the crystallization to be pi-pi stacking of the rather stiff biphenylene groups.

Hydrogen generation from renewable energy sources will play a key role in the concerted endeavor to constrain climate change. One environmentally friendly route, powered by sunlight, is the photoelectrochemical water splitting cell (PEC). This technology employs electrodes coated with thin films of semiconductor materials to capture light and generate charge carriers that directly drive the water splitting reaction. Bismuth vanadate is a promising metal oxide semiconductor, as it absorbs visible light, and is abundant, non-toxic and cost-effective. The present study investigates the formation of bismuth vanadate thin films by the aerosol deposition (AD) method. Operating with layer formation at room temperature, AD offers advantages over other routes for the fabrication of photoactive thin film coatings, as no binders or sintering processes need to be applied. Furthermore, compared to traditional cold spraying, micrometer-sized particles can be used, resulting in coatings with thicknesses below 1 µm. Additionally, the lower kinetic energy of the feedstock powder particles enables the use of delicate substrates, such as FTO-coated glass, expanding the range of possible PEC device configurations. The process parameters explored in this study had considerable influence on the resulting coating microstructure, which in turn showed a significant impact on the photoelectrochemical performance.

In order to enable mass production of photocatalytically active electrodes for direct conversion of solar energy into hydrogen, abundant materials and inexpensive preparation methods are needed. BiVO4 photoelectrodes prepared by aerosol deposition satisfy these requirements, in addition offering reasonable photocurrent densities, and can potentially contribute to the establishment of a prospective economy based on hydrogen as energy source. Nevertheless, in order to allow the economically feasible implementation of BiVO4 electrodes for direct water splitting, there is need for further improvement of the electrodes efficiency. In particular, an increased understanding of factors limiting the photocurrent is needed. In this work, BiVO4 photoelectrodes, prepared by aerosol deposition of BiVO4 particles on FTO-substrates, were investigated by surface photovoltage (SPV) as well as photocurrent and Mott-Schottky measurements. Surface photovoltage spectroscopy under front and back illumination gives evidence of limitation of charge transport by a significant lower mobility of electrons compared to holes, leading to a nearly tenfold higher photocurrent, when illuminated from the back, compared to illumination from the front. Furthermore, the presence of traps for holes as well as for electrons on the BiVO4 surface has been confirmed by transient surface photovoltage spectroscopy and their influence on the photocurrent is discussed. Figure 1

Graphene oxide is functionalized with poly(2-diethylaminoethyl) methacrylate (PDEAEMA), and the resulting material is used as a selective layer of a thin-film composite membrane (TFCM). The polymer synthesis is carried out by surface-initiated atom transfer radical polymerization (SI-ATRP) from bulk and also from single-layer graphene oxide (GO). The polymer brushes synthesized by the "grafting from" method are characterized by size exclusion chromatography (SEC), nuclear magnetic resonance spectroscopy (NMR), Fourier-transform infrared (FTIR) spectroscopy, thermal gravimetric analysis (TGA), and TGA-FTIR. The TFCMs are prepared by the deposition of the selective layer from a stable polymer solution. The molecular weight of the polymer is sufficiently high to obtain a continuous defect-free layer on a porous support. The thickness of the selective layer is approximate to 400 nm, as found in morphological investigations by scanning electron microscopy (SEM). The obtained membranes are utilized for gas and water vapor transport experiments in a wide temperature range. The water vapor permeability coefficient of the investigated materials is up to 4500 Barrer; this value increases threefold upon quaterization of the amine. The high permeance and selectivity for water vapor make this type of thin-film membranes a potential candidate for membrane distillation.

In this work, the hydrogen sorption properties of the LiBH4–Mg2NiH4 composite system with the molar ratio 2:2.5 were thoroughly investigated as a function of the applied temperature and hydrogen pressure. To the best of our knowledge, it has been possible to prove experimentally the mutual destabilization between LiBH4 and Mg2NiH4. A detailed account of the kinetic and thermodynamic features of the dehydrogenation process is reported here.

Lithium borohydride (LiBH4) and sodium borohydride (NaBH4) were synthesized via mechanical milling of LiBO2, and NaBO2 with Mg–Al-based waste under controlled gaseous atmosphere conditions. Following this approach, the results herein presented indicate that LiBH4 and NaBH4 can be formed with a high conversion yield starting from the anhydrous borates under 70 bar H2. Interestingly, NaBH4 can also be obtained with a high conversion yield by milling NaBO2·4H2O and Mg–Al-based waste under an argon atmosphere. Under optimized molar ratios of the starting materials and milling parameters, NaBH4 and LiBH4 were obtained with conversion ratios higher than 99.5%. Based on the collected experimental results, the influence of the milling energy and the correlation with the final yields were also discussed.

Dense, nanostructured bismuth vanadate thin films were successfully deposited by aerosol deposition at room temperature. Aerosol deposition offers an alternative route for fabrication of photoactive metal oxide coatings as no binders or sintering processes are employed. A micron-sized bismuth vanadate powder was used to spray photoactive films (< 1 µm) on conductive fluor-doped tin oxide layers on glass and titanium substrates. The thin films are photocatalytically active under solar light due to the band gap energies of bismuth vanadate, and their nanosized structure increases surface area and catalytic activity. The coatings obtained were assessed based on microstructure, layer thickness, mechanical integrity, and photoelectrochemical activity.

Aromatic polyimides containing different ratios of ortho-hydroxy to ortho-allyloxy units were prepared and thermally rearranged.

Solid-state hydride compounds are a promising option for efficient and safe hydrogen-storage systems. Lithium reactive hydride composite system 2LiBH(4) + MgH2/2LiH + MgB2 (Li-RHC) has been widely investigated owing to its high theoretical hydrogen-storage capacity and low calculated reaction enthalpy (11.5 wt % H-2 and 45.9 kJ/mol H-2). In this paper, a thorough investigation into the effect of the formation of nano-TiAl alloys on the hydrogen-storage properties of Li-RHC is presented. The additive 3TiCl(3)center dot AlCl3 is used as the nanoparticle precursor. For the investigated temperatures and hydrogen pressures, the addition of similar to 5 wt % 3TiCl(3)center dot AlCl3 leads to hydrogenation/dehydrogenation times of only 30 min and a reversible hydrogen-storage capacity of 9.5 wt %. The material containing 3TiCl(3)center dot AlCl3 possesses superior hydrogen-storage properties in terms of rates and a stable hydrogen capacity during several hydrogenation/dehydrogenation cycles. These enhancements are attributed to an in situ nanostructure and a hexagonal AlTi3 phase observed by high-resolution transmission electron microscopy. This phase acts in a 2-fold manner, first promoting the nucleation of MgB2 upon dehydrogenation and second suppressing the formation of Li2B12H12 upon hydrogenation/dehydrogenation cycling.

Electronic states in BiVO4 powders and in cold gas sprayed BiVO4 coatings were characterized by modulated and transient surface photovoltage (SPV) spectroscopy. The SPV signals measured in the spectral ranges between 2.2 and 2.5-2.6 eV and above 2.6 eV were negative and positive, respectively. Therefore, electrons (holes) photo-generated from defect states near the surface or photo-generated by fundamental absorption in the bulk were predominantly separated towards the bulk (surface) or towards the external surface (bulk), respectively. Bulk defect states dominating the modulated SPV signals between 1.8 and 2.2 eV were observed after cold gas spraying but disappeared after moderate post-annealing. Random walk simulations of SPV signals gave evidence for transport limitation by hopping for excitation from defect states.

Cold gas spraying (CGS) is presented as an innovative approach to deposit semiconductor particles onto substrates in order to produce photoelectrodes for electrochemical applications, e.g. the oxygen evolution reaction (OER). The spraying technique is characterized by high velocity particles which impact and deposit on a surface at relatively low temperature. Compared to established wet-chemical techniques, an increased photoelectrochemical activity is observed due to an enhanced particle-to-substrate bonding. For closer investigation of the influence of the process parameters on the photoelectrochemical activity, TiO2 electrodes (P25-20 by Evonik Industries) sprayed with different carrier gases (nitrogen, argon, helium) are analyzed. Due to different acceleration conditions of the particles in the de Laval nozzle, these carrier gases allow to investigate the influence of the impact energy of the particles on the binding mechanism and thus the resulting photocurrent density in the OER. Photoelectrochemical activities, structural properties as well as the electrode structure are correlated in order to discuss the history of the semiconductor and its photoelectrochemical properties evoked in the CGS process. Surface photovoltage measurements are considered to analyze the charge carrier dynamics in the porous TiO2 film. For the gas carrier nitrogen, beneficial conditions for the particle-to-particle and particle-to-substrate coupling are provided due to the sufficient temperature and velocity of the particles. (C) 2015 Elsevier B.V. All rights reserved.

New CO2 selective blend materials were tested for gas transport properties as thick film and thin film composite membrane.

This paper considers Pebax® MH 1657 as a material for the CO2/N2 separating layer in thin film composite (TFC) membranes. The CO2 permeability of Pebax® can be improved via blending with various poly(ethylene oxide) (PEO) based materials without loss of CO2/N2 selectivity. Analogous blends containing PEOs with reactive end groups have been investigated for the possibility of a network formation within the Pebax® matrix. The formation of network is possible through the reaction between two types of additives containing two reactive end groups. The thick film samples and TFC membranes were prepared from mixtures of Pebax® MH 1657, PEG DG526 and JEFFAMINE® with different molecular weights. The samples were characterized by single gas permeation measurements, DSC, and NMR. The samples with incorporated networks show improved and stable gas transport properties compared to the original polymer for both thick films and TFC membranes.