1D p–n Junction Electronic and Optoelectronic Devices from Transition Metal Dichalcogenide Lateral Heterostructures Grown by One-Pot Chemical Vapor Deposition Synthesis

Lateral heterostructures of dissimilar monolayer transition metal dichalcogenides provide great opportunities to build 1D in-plane p–n junctions for sub-nanometer thin low-power electronic, optoelectronic, optical, and sensing devices. Electronic and optoelectronic applications of such p–n junction devices fabricated using a scalable one-pot chemical vapor deposition process yielding MoSe₂-WSe₂ lateral heterostructures are reported here. The growth of the monolayer lateral heterostructures is achieved by in situ controlling the partial pressures of the oxide precursors by a two-step heating protocol. The grown lateral heterostructures are characterized structurally and optically using optical microscopy, Raman spectroscopy/microscopy, and photoluminescence spectroscopy/microscopy. High-resolution transmission electron microscopy further confirms the high-quality 1D boundary between MoSe₂ and WSe₂ in the lateral heterostructure. p–n junction devices are fabricated from these lateral heterostructures and their applicability as rectifiers, solar cells, self-powered photovoltaic photodetectors, ambipolar transistors, and electroluminescent light emitters are demonstrated.     

Electrocatalytic applications of platinum-decorated TiO<Subscript>2</Subscript> nanotubes prepared by a fully wet-chemical synthesis

Pt-decorated \(\hbox {TiO}_{2}\) nanotubes Pt@TiO₂ are prepared only by applying a set of facile wet-chemical redox reactions to ion track-etched polycarbonate templates. First, a homogeneous layer of Pt nanoparticles is deposited onto the complex template surface by reducing potassium tetrachloroplatinate with absorbed dimethylaminoborane. Second, the template is coated with a conformal \(\hbox {TiO}_{2}\) layer, using a chemical bath deposition reaction based on titanium(III) chloride. After the removal of the template, the rutile-type \(\hbox {TiO}_{2}\) nanotubes remain decorated with Pt nanoparticles and nanoparticle-clusters on their outside. During the process, neither vacuum techniques nor external current sources or addition of heat are employed. The crystallinity, composition, and morphology of the composite nanotubes are analysed by X-ray diffraction, scanning and transmission electron microscopy as well as by energy-dispersive X-ray spectroscopy. Finally, the obtained materials are examplarily applied in the electrooxidation of ethanol and formic acid, and their performances have been evaluated. Compared to conventional carbon black-supported Pt nanoparticles, the Pt@TiO₂ nanotubes show higher reaction rates. Mass activities of 2.36 \(\hbox {A}\hbox { mg}_{\rm Pt}^{-1}\hbox { cm}^{-2}\) are reached in ethanol oxidation and 7.56 \(\hbox {A}\hbox { mg}_{\rm Pt}^{-1}\hbox { cm}^{-2}\) in the formic acid oxidation. The present structures are able to exploit the synergy of Pt and \(\hbox {TiO}_{2}\) with a bifunctional mechanism to result in powerful but easy-to-fabricate catalyst structures. They represent an easily producible type of composite nanostructures which can be applied in various fields such as in catalytics and sensor technology.     

EPDM based weatherable PVC impact modifiers

Graft polyblends of styrene, acrylonitrile or methyl methacrylate with EPDM rubbers are PVC impact modifiers. Specific compositions in PVC composites have unaged impact strengths similar to PVC composites with commercial ABS, polyacrylate, and chlorinated polyethylene modifiers at equivalent concentrations. Modifier efficiency and weatherability of the EPDM based modifiers are compared to ABS, polyacrylate, and chlorinated polyethylene.     

Plant availability of inorganic and organic selenium fertiliser as influenced by soil organic matter content and pH

The objective of the present study was to investigate the influence of soil organic matter content and pH on plant availability of both inorganic and organic selenium (Se) fertilisers. Further, the risk of Se leaching after application of inorganic Se fertiliser was evaluated. A new interpretation of an older field study at different sites in Southern Norway showed that organic C was correlated with grain Se concentration in wheat, barley and oats, explaining up to 60% of the variation in Se concentration. Pot experiments with a peat soil, a loam soil and a peat/loam soil mixture were conducted for the present study at a range of pH values between pH 5 and 7. Below pH 6, Se uptake from added Se fertiliser was higher in the soil types with high organic matter content than in the loam. The opposite occurred at a soil pH above 6, where Se uptake was higher in the loam than in the peat soil. A simple leaching experiment after one growing season confirmed the findings of the pot experiments that Se availability in the loam soil with a relatively low organic matter content increased with increasing pH, whereas it decreased in the peat soil. Neither Se yeast, nor pure Se methionine, used as organic Se fertiliser, resulted in any significant uptake of Se when added at concentrations similar to the inorganic Se applications.     

The effect of fatty acid composition on biodiesel oxidative stability

Concerning their environmental impact, native based fuels and lubricants show immense potential. In fact, these products are highly exposed to oxidative processes during storage or application [1, 2]. One way to raise oxidative stabilities is the addition of synthetic antioxidants. Another way may be the modification of the fatty acid composition, since polyunsaturated fatty acids show a much higher proneness to autoxidation. In order to decrease the content of polyunsaturated and to raise the content of saturated components, experiments for fractional distillation and crystallisation as well as for hydrogenation of fatty acid methyl esters have been carried out. In distillation experiments with separation columns the methyl esters performed good separation of the lower‐boiling esters with a chain‐length up to 16C‐atoms, from the C‐18 fraction, causing a degree of saturation up to 75 wt‐% in the distillate. In tests with fractional crystallisation, the rate of saturation could be raised up to 92.8 wt‐%. Using the process of catalytic hydrogenation, a rate of saturation up to 100 wt‐% could be achieved, depending on the duration of the hydrogenation process. By partial hydrogenation of the polyunsaturated components, products with high oxidation stability and low pour point could be produced within relatively short hydrogenation time.     

Polarization effects in a porous air cathode due to the influence of the anode in an alkaline air-metal cell

Experiments in 6 N KOH at room temperature with air-zinc and air-cadmium cells show clearly that the anodes have an influence on the polarization of the porous air cathode. The electrolyte volume is also found to have an effect. At a constant load of 30 mA/cm² the polarization curve for oxygen reduction at the air cathode was, depending on cell arrangement, shifted by up to about 150 mV in the direction of more negative values compared to that measured in the half-cell. Moreover, in some cases, this negative shift was followed by a smaller positive one. These effects are discussed in terms of the concentration of HO₂ ^–-ions, which are produced by Berl's reaction mechanism, and of the potential and the surface state of the anode.     

The microstructure of a ZnO varistor material

The microstructure of a ZnO varistor material has been investigated by a combination of X-ray diffractometry and analytical electron microscopy (SEM, TEM, STEM, EDX). The material was found to consist of: ZnO grains (doped with manganese, cobalt and nickel); smaller spinel grains which hinder the growth of ZnO grains during sintering; intergranular Bi-rich phases (namely -Bi₂O₃, pyrochlore and an amorphous phase); and a small proportion of ZnO-ZnO interfaces which did not have any intergranular film but to which bismuth had segregated. The intergranular microstructure is largely a result of processes which occur during liquid phase sintering and subsequent cooling to room temperature.     

Quantitative atom probe analysis of carbides

Compared to atom probe analysis of metallic materials, the analysis of carbide phases results in an enhanced formation of molecular ions and multiple events. In addition, many multiple events appear to consist of two or more ions originating from adjacent sites in the material. Due to limitations of the ion detectors measurements generally underestimate the carbon concentration. Analyses using laser-pulsed atom probe tomography have been performed on SiC, WC, Ti(C,N) and Ti₂AlC grains in different materials as well as on large M₂₃C₆ precipitates in steel. Using standard evaluation methods, the obtained carbon concentration was 6-24% lower than expected from the known stoichiometry. The results improved remarkably by using only the ¹³C isotope, and calculating the concentration of ¹²C from the natural isotope abundance. This confirms that the main reason for obtaining a too low carbon concentration is the dead time of the detector, mainly affecting carbon since it is more frequently evaporated as multiple ions. In the case of Ti(C,N) and Ti₂AlC an additional difficulty arises from the overlap between C₂⁺, C₄²⁺ and Ti²⁺ at the mass-to-charge 24 Da.     

A pilot-plant scale evaluation of potential precipitants in the secondary precipitation process

Chemical precipitation of presettled domestic wastewater (secondary precipitation) was studied in three pilot-plants operating in parallel with alum, ferric iron and lime as precipitants. With all precipitants phosphates were effectively removed down to less than 0·1 mg P l⁻¹. Total phosphorus removals were closely connected to the settling properties of the flocs. The factor that seemed to influence settling properties most was pH. In a favourable pH-range it was possible to achieve total phosphorus concentrations in the effluent of less than 0·5 mg P l⁻¹. The COD removal was at an average 70, 60 and 55% with alum, ferric iron and lime as precipitants.     

Exploring characteristics and transformational capabilities of InsurTech innovations to understand insurance value creation in a digital world

Recent developments in the insurance industry embrace various “Insurance Technology” (InsurTech) innovations. To date, there is a lack of structured assessments of InsurTech. Prior research on FinTech fails (1) to clarify how InsurTech can be characterized and what capabilities are employed, and hence, (2) to reveal implications for value creation on firm and industry level. We address this by inductively building a model of InsurTech innovation adopting the grounded theory method. Our empirical data includes 208 InsurTech innovations from a market analysis based on Twitter data and a multiple-case study. The resulting model comprises 52 characteristics and 14 transformational capabilities and is integrated with extant value networks and intermediation literature. The former explains how InsurTech affects firm-level value creation and suggests that disruptive potentials emerge from aligning the transformational capabilities along three interdependent activities. The latter explains the entrance of digital intermediaries and their roles in the personal insurance market.