Abstract: CO2 conversion into value-added chemicals and fuels is considered as one of the great challenges of the 21st century. Due to the limitations of the traditional thermal approaches, several novel technologies are being developed. One promising approach in this field, which has received little attention to date, is plasma
technology. Its advantages include mild operating conditions, easy upscaling, and gas activation by energetic electrons instead of heat. This allows thermodynamically difficult reactions, such as CO2 splitting and the dry reformation of methane, to occur with reasonable energy cost. In this review, after exploring the traditional thermal approaches, we have provided a brief overview of the fierce competition between various novel approaches in a quest to find the most effective and efficient CO2 conversion technology. This is needed to critically assess whether plasma technology can be successful in an already crowded arena. The following questions need to be answered in this regard: are there key advantages to using plasma technology over other novel approaches, and if so, what is the flip side to the use of this technology? Can plasma technology be successful on its own, or can synergies be achieved by combining it with other technologies? To answer
these specific questions and to evaluate the potentials and limitations of plasma technology in general, this review presents the current state-of-the-art and a critical assessment of plasma-based CO2 conversion, as well as the future challenges for its practical implementation.

Abstract: We report on multi-level atomistic simulations for the interaction of reactive oxygen species (ROS) with the head groups of the phospholipid bilayer, and the subsequent effect of head group and lipid tail oxidation on the structural and dynamic properties of the cell membrane. Our simulations are validated by experiments using a cold atmospheric plasma as external ROS source. We found that plasma treatment leads to a slight initial rise in membrane rigidity, followed by a strong and persistent increase in fluidity, indicating a drop in lipid order. The latter is also revealed by our simulations. This study is important for cancer treatment by therapies producing (extracellular) ROS, such as plasma treatment. These ROS will interact with the cell membrane, first oxidizing the head groups, followed by the lipid tails. A drop in lipid order might allow them to penetrate into the cell interior (e.g., through pores created due to oxidation of the lipid tails) and cause intracellular oxidative damage, eventually leading to cell death. This work in general elucidates the underlying mechanisms of ROS interaction with the cell membrane at the atomic level.

Abstract: Radiation-induced modifications of nanostructures are of fundamental interest and constitute a viable out-of-equilibrium approach to the development of novel nanomaterials. Herein, we investigated the structural transformation of silica-coated CdSe/CdS nanorods (NRs) under femtosecond (fs) illumination. By comparing the same nanorods before and after illumination with different fluences we found that the silica-shell did not only enhance the stability of the NRs but that the confinement of the NRs also led to novel morphological and chemical transformations. Whereas uncoated CdSe/CdS nanorods were found to sublimate under such excitations the silica-coated nanorods broke into fragments which deformed towards a more spherical shape. Furthermore, CdS decomposed which led to the formation of metallic Cd, confirmed by high-resolution electron microscopy and energy dispersive X-ray spectrometry (EDX), whereby an epitaxial interface with the remaining CdS lattice was formed. Under electron beam exposure similar transformations were found to take place which we followed in situ.

Abstract: Doped Cr2O3 has been shown to be a p-type transparent conducting oxide (TCO). Its conductivity, however, is low. As for most p-type TCOs, the main problem is the high effective hole mass due to flat valence bands. We use first-principles methods to investigate whether one can increase the valence band dispersion (i.e. reduce the hole mass) by anion alloying with sulfur, while keeping the band gap large enough for transparency. The alloying concentrations considered are given by Cr(4)SxO(6-x), with x = 1-5. To be able to describe the electronic properties of these materials accurately, we first study Cr2O3, examining critically the accuracy of different density functionals and methods, including PBE, PBE+U, HSE06, as well as perturbative approaches within the GW approximation. Our results demonstrate that Cr4S2O4 has an optical band gap of 3.08 eV and an effective hole mass of 1.8 m(e). This suggests Cr4S2O4 as a new p-type TCO host candidate.

Abstract: The crucial requirement for diamond growth at low temperatures, enabling a wide range of new applications, is a high plasma density at a low gas pressure, which leads to a low thermal load onto sensitive substrate materials. While these conditions are not within reach for resonance cavity plasma systems, linear antenna microwave delivery systems allow the deposition of high quality diamond films at temperatures around 400 degrees C and at pressures below 1 mbar. In this work the codeposition of high quality plates and octahedral diamond grains in nanocrystalline films is reported. In contrast to previous reports claiming the need for high temperatures (T >= 850 degrees C), low temperatures (320 degrees C <= T <= 410 degrees C) were sufficient to deposit diamond plate structures. Cross-sectional high resolution transmission electron microscopy studies show that these plates are faulty cubic diamond terminated by large {111} surface facets with very little sp(2) bonded carbon in the grain boundaries. Raman and electron energy loss spectroscopy studies confirm a high diamond quality, above 93% sp(3) carbon content. Three potential mechanisms, that can account for the initial development of the observed plates rich with stacking faults, and are based on the presence of impurities, are proposed.

Abstract: Colloidal CsPbX3 (X = Br, Cl, and I) perovskite nanocrystals (NCs) have emerged as promising phosphors and solar cell materials due to their remarkable optoelectronic properties. These properties can be tailored by not only controlling the size and shape of the NCs but also postsynthetic composition tuning through topotactic
anion exchange. In contrast, property control by cation exchange is still underdeveloped for colloidal CsPbX3 NCs. Here, we present a method that allows partial cation exchange in colloidal CsPbBr3 NCs, whereby Pb2+ is exchanged for several isovalent cations, resulting in doped CsPb1−xMxBr3 NCs (M= Sn2+, Cd2+, and Zn2+; 0 < x ≤ 0.1), with preservation of the original NC shape. The size of the parent NCs is also preserved in the product NCs, apart from a small (few
%) contraction of the unit cells upon incorporation of the guest cations. The partial Pb2+ for M2+ exchange leads to a blue-shift of the optical spectra, while maintaining the high photoluminescence quantum yields (>50%), sharp absorption features, and narrow emission of the parent CsPbBr3 NCs. The blue-shift in the optical spectra is attributed to the lattice contraction that accompanies the Pb2+ for M2+ cation exchange and is observed to scale linearly with the lattice contraction. This work opens up new possibilities to engineer the properties of halide perovskite NCs, which to date are demonstrated to be the only known
system where cation and anion exchange reactions can be sequentially combined while preserving the original NC shape, resulting in compositionally diverse perovskite NCs.

Abstract: The ability of metal-organic frameworks (MOFs) to gelate under specific synthetic conditions opens up new opportunities in the preparation and shaping of hierarchically porous MOF monoliths, which could be directly implemented for catalytic and adsorptive applications. In this work, we present the first examples of xero-or aerogel monoliths consisting solely of nanoparticles of several prototypical Zr4+-based MOFs: UiO-66-X (X – H, NH2, NO2, (OH)(2)), UiO-67, MOF-801, MOF-808 and NU-1000. High reactant and water concentrations during synthesis were observed to induce the formation of gels, which were converted to monolithic materials by drying in air or supercritical CO2. Electron microscopy, combined with N-2 physisorption experiments, was used to show that irregular nanoparticle packing leads to pure MOF monoliths with hierarchical pore systems, featuring both intraparticle micropores and interparticle mesopores. Finally, UiO-66 gels were shaped into monolithic spheres of 600 mm diameter using an oil-drop method, creating promising candidates for packed-bed catalytic or adsorptive applications, where hierarchical pore systems can greatly mitigate mass transfer limitations.

Abstract: This study reports on the synthesis and characterization of MAX phases in the (Zr,Ti)n+1AlCn system. The MAX phases were synthesized by reactive hot pressing and pressureless sintering in the 1350–1700 °C temperature range. The produced ceramics contained large fractions of 211 and 312 (n = 1, 2) MAX phases, while strong evidence of a 413 (n = 3) stacking was found. Moreover, (Zr,Ti)C, ZrAl2, ZrAl3, and Zr2Al3 were present as secondary phases. In general, the lattice parameters of the hexagonal 211 and 312 phases followed Vegard’s law over the complete Zr-Ti solid solution range, but the 312 phase showed a non-negligible deviation from Vegard’s law around the (Zr0.33,Ti0.67)3Al1.2C1.6 stoichiometry. High-resolution scanning transmission electron microscopy combined with X-ray diffraction demonstrated ordering of the Zr and Ti atoms in the 312 phase, whereby Zr atoms occupied preferentially the central position in the close-packed M6X octahedral layers. The same ordering was also observed in 413 stackings present within the 312 phase. The decomposition of the secondary (Zr,Ti)C phase was attributed to the miscibility gap in the ZrC-TiC system.

Abstract: Chrome yellow refers to a group of synthetic inorganic pigments that became popular as an artists material from the second quarter of the 19th century. The color of the pigment, in which the chromate ion acts as a chromophore, is related to its chemical composition (PbCr1-xSxO4, with 0≤x≤0.8) and crystalline structure (monoclinic/orthorhombic). Their shades range from the yellow-orange to the paler yellow tones with increasing sulfate amount. These pigments show remarkable signs of degradation after limited time periods. Pure PbCrO4 (crocoite in its natural form) has a deep yellow color and is relatively stable, while the co-precipitate with lead sulfate (PbCr1-xSxO4) has a paler shade and seems to degrade faster. This degradation is assumed to be related to the reduction of Cr(VI) to Cr(III). We show that on increasing the sulfur(S)-content in chrome yellow, the band gap increases. Typically, when increasing the band gap, one might assume that a decrease in photo activity is the result. However, the photo activity relative to the Cr content, and thus Cr reduction, of sulfur-rich PbCr1-xSxO4 is found to be much higher compared to the sulfur-poor or non-doped lead chromates. This discrepancy can be explained by the evolution of the crystal and electronic structure as function of the sulfur content: first-principles density functional theory calculations show that both the absorption coefficient and reflection coefficients of the lead chromates change as a result of the sulfate doping in such a way that the generation of electron-hole pairs under illumination relative to the total Cr content increases. These changes in the material properties explain why paler shade yellow colors of this pigment are more prone to discoloration. The electronic structure calculations also demonstrate that lead chromate and its co-precipitates are p-type semiconductors, which explains the observed reduction reaction. As understanding this phenomenon is valuable in the field of cultural heritage, this study is the first joint action of photo-electrochemical measurements and first-principles calculations to approve the higher tendency of sulfur-rich lead chromates to darken.

Abstract: The noncentrosymmetric tungstate oxide, Ce18W10O57) was synthesized for the first time as high-quality single crystals via the molten chloride flux method and structurally characterized by single-crystal X-ray diffraction. The compound is a structural analogue to the previously reported La18W10O57, which crystallizes in the hexagonal space group P (6) over bar 2c. The +3 oxidation state of cerium in Ce18W10O57 was achieved via the in situ reduction of Ce(IV) to Ce(III) using Zn metal. The structure consists of both isolated and face-shared WO6 octahedra and, surprisingly, isolated WO6 trigonal prisms. A careful analysis of the packing arrangement in the structure makes it possible to explain the unusual structural architecture of Ce18W10O57, which is described in detail. The temperature-dependent magnetic susceptibility of Ce18W10O57 indicates that the cerium(III) f(1) cations do not order magnetically and exhibit simple paramagnetic behavior. The SHG efficiency of Ln(18)W(10)O(57) (Ln = La, Ce) was measured as a function of particle size, and both compounds were found to be SHG active with efficiency approximately equal to that of alpha-SiO2.

Abstract: Conventional carbon dioxide (CO2) separation in the petrochemical industry via cryogenic distillation is energy intensive and environmentally unfriendly. Alternatively, polymer membrane-based separations are of significant interest owing to low production cost, low-energy consumption and ease of upscaling. However, the implementation of commercial polymeric membranes is limited by their permeability and selectivity trade-off and the insufficient thermal and chemical stability. Herein, a novel type of amorphous mixed matrix membrane (MMM) able to separate CO2/CH4 mixtures with the highest selectivities ever reported for MOF based MMMs is presented. The MMM consists of an amorphised metal-organic framework (MOF) dispersed in an oxidatively cross-linked matrix achieved by fine tuning of the thermal treatment temperature in air up to 350 degrees C which drastically boosts the separation properties of the MMM. Thanks to the protection of the surrounding polymer, full oxidation of this MOF (i.e. ZIF-8) is prevented, and amorphisation of the MOF is realized instead, thus in situ creating a molecular sieve network. In addition, the treatment also improves the filler-polymer adhesion and induces an oxidative cross-linking of the polyimide matrix, resulting in MMMs with increased stability or plasticization resistance at high pressure up to 40 bar, marking a new milestone as new molecular sieve MOF MMMs for challenging natural gas purification applications. A new field for the use of amorphised MOFs and a variety of separation opportunities for such MMMs are thus opened.

Abstract: Quantum spin Hall (QSH) insulators with a large topologically nontrivial bulk gap are crucial for future applications of the QSH effect. Among these, group III-V monolayers and their halides, which have a chair structure (regular hexagonal framework), have been widely studied. Using first-principles calculations, we formulate a new structure model for the functionalized group III-V monolayers, which consist of rectangular GaBi-X-2 (X = I, Br, Cl) monolayers with a distorted hexagonal framework (DHF). These structures have a far lower energy than the GaBi-X-2 monolayers with a chair structure. Remarkably, the DHF GaBi-X-2 monolayers are all QSH insulators, which exhibit sizeable nontrivial band gaps ranging from 0.17 to 0.39 eV. The band gaps can be widely tuned by applying different spin-orbit coupling strengths, resulting in a distorted Dirac cone.

Abstract: Air pollutants from fossil fuel fired power plants harm the environment and human health. More than 91% of Irans electricity production is from thermal power plants that use natural gas, diesel, and fuel oil. We apply the impact pathway approach to estimate the health impacts arising from Iranian fossil-based electricity generation emission, and in a next step, we calculate monetary costs of the estimated damages, for a one-year period starting from 20 March 2016 through 2017. We use the new version of SIMPACTS (International Atomic Energy Agency, Vienna, Austria) to investigate the health effects from 61 major Iran fossil-based power plants separately. The selected plants represent 95.6% of total Iran fossil-based power generation. Using the individual and different power plant estimates, we avoid extrapolation and our results can be considered more reliable, taking into account spatial differences. The total damage cost is 723.42 million USD (2000). The damage cost per generated electricity varies from 0.06 to 22.41 USD/MWh and average plant damage cost is 2.85 USD/MWh. Accounting for these external costs indicates the actual costs of fossil energy. The results are useful for policy makers to compare the health costs from these plants and to decide on cleaner energy sources and to take measures to increase benefits for society.

Abstract: The conversion of atmospheric nitrogen into valuable compounds, that is, so-called nitrogen fixation, is gaining increased interest, owing to the essential role in the nitrogen cycle of the biosphere. Plasma technology, and more specifically gliding arc plasma, has great potential in this area, but little is known about the underlying mechanisms. Therefore, we developed a detailed chemical kinetics model for a pulsed-power gliding-arc reactor operating at atmospheric pressure for nitrogen oxide synthesis. Experiments are performed to validate the model and reasonable agreement is reached between the calculated and measured NO and NO2 yields and the corresponding energy efficiency for NOx formation for different N2/O2 ratios, indicating that the model can provide a realistic picture of the plasma chemistry. Therefore, we can use the model to investigate the reaction pathways for the formation and loss of NOx. The results indicate that vibrational excitation of N2 in the gliding arc contributes significantly to activating the N2 molecules, and leads to an energy efficient way of NOx production, compared to the thermal process. Based on the underlying chemistry, the model allows us to propose solutions on how to further improve the NOx formation by gliding arc technology. Although the energy efficiency of the gliding-arc-based nitrogen fixation process at the present stage is not comparable to the world-scale Haber–Bosch process, we believe our study helps us to come up with more realistic scenarios of entering a cutting-edge innovation in new business cases for the decentralised production of fertilisers for agriculture, in which lowtemperature plasma technology might play an important role.

Abstract: We investigate the role of transition metal atoms of group V-b (V, Nb, Ta) and VI-b (Cr, Mo, W) as n- or p-type dopants in anatase TiO$_2$ using thermodynamic
principles and density functional theory with the Heyd-Scuseria-Ernzerhof HSE06 hybrid functional. The HSE06 functional provides a realistic value for the band gap, which ensures a correct classification of dopants as shallow or deep donors or acceptors. Defect formation energies and thermodynamic transition levels are calculated taking into account the constraints imposed by the stability of TiO$_2$ and the solubility limit of the impurities.
Nb, Ta, W and Mo are identified as shallow donors. Although W provides two electrons, Nb and Ta show a considerable lower formation energy, in particular under O-poor conditions. Mo donates in principle one electron, but under specific conditions can turn into a double donor. V impurities are deep donors and Cr
shows up as an amphoteric defect, thereby acting as an electron trapping center in n-type TiO$_2$ especially under O-rich conditions. A comparison with the available experimental data yields excellent agreement.