Targeting interstitial atoms in n-type Mg 3 (Bi, Sb) 2 single crystals for robust ambient energy conversion

Recently, alkali metal doped ZnO has received much positive attention owing to its high performance and good electrical stability. In particular, since alkali metals such as Li and Na are general elements and show good potential as doping elements in ZnO semiconductors, several researchers have been interested in alkali metal doping process of polycrystalline zinc oxide semiconductors. However, only a few studies have been reported the doping mechanism to enhance the mobility. In addition, there have been few studies on alkali metal doping mechanism in amorphous metal oxide semiconductors. Most studies about alkali metal doped oxide semiconductor have been inquired in term of crystallinity, oxygen vacancy, and surface morphology properties. For these reasons, we also studied the mechanism of alkali metal doping in view of oxygen vacancy by spectroscopic study using XPS and surface morphology using AFM. However, although we observed that oxygen vacancy contents are reduced slightly with a correlation by interstitial or substitutional mechanism, it seems to be difficult to identify the correlation between the enhancement of electrical properties induced by interstitial doping and the changes of oxygen vacancy contents, because the difference of XPS spectra in doped ZTO films is too small. Also, as the decrease of oxygen vacancy contents means the decrease of electron mobility in metal oxide semiconductors, the tendency of oxygen vacancy spectra in XPS is inconsistence with general phenomena. It means that other mechanisms are required to precisely explain the electrical properties of the doped amorphous ZTO TFTs related to alkali metal doping mechanism. Otherwise, the change in the optical band gap supported by the Burstein-moss theory showed successfully that the enhancement of mobility was related to the interstitial doping of alkali metals. This result shows that the change of the optical band gap clearly applied to the study of the relationship between the change in mobility and interstitial doping concentrations.Here in, we introduce alkali metals doped and solution processed amorphous zinc tin oxide (ZTO) semiconductor TFTs, which show better electrical properties, such as field effect mobility and conductivity, than that of intrinsic amorphous ZTO based TFTs. We also analyze that the doping mechanism of alkali metals in the amorphous ZTO based TFTs using various techniques such as, atomic force microscopy (AFM), X-ray photoemission spectroscopy (XPS), Hall mobility. Furthermore, through the UV-visible spectroscopy, we suggest a comprehensive technique for investigating the enhanced electrical performance induced by alkali metal doping in terms of the change in optical band gap. Specially, we showed that UV-visible spectroscopic analysis for investigating the electrical performance of alkali metal doped metal oxide semiconductor TFTs has good potential as a fast and non-destructive analytical technique.

Thermal energy storage utilizing the adsorption of moisture from air is a promising energy storage technology due to its high energy density and minimum heat losses. Salt hydrates and salt hydrate composites, such as calcium chloride (CaCl2) and CaCl2-based composites, have shown favourable energy storage properties in this area of research. However, these materials have shown issues with stability due to swelling and deliquescence. In this work, CaCl2 was stabilized using three methods: impregnation into silica gel, encapsulation in methyl cellulose, and both impregnation and encapsulation stabilization techniques used simultaneously. Therefore, three CaCl2-based composites were synthesized. For the first composite, silica gel was impregnated with CaCl2. For the second composite, CaCl2 was encapsulated by methyl cellulose. For the third composite, silica gel was impregnated with CaCl2 and the CaCl2 was encapsulated with methyl cellulose. These samples were structurally characterized using scanning electron microscopy as well as Brunauer-Emmett-Teller (BET) to determine surface area, pore size distribution and nitrogen adsorption isotherms at 77 K. Water vapour adsorption isotherms were also determined at 25 °C for different relative humidities by dynamic vapor sorption (DVS). Similarly, LiCl-based composites were also synthesized and examined in this work, but issues of deliquescence, swelling, and agglomeration made the materials impractical to work with. To determine the prepared materials’ thermal energy storage performance, 2–6 g of each sample was tested in a lab-scale apparatus. This process uses the exothermic adsorption of moisture from ambient air in an open thermal energy storage system. The CaCl2 impregnated silica gel that was encapsulated in methyl cellulose showed reasonably high stability and energy storage performance after 3 hydration and dehydration cycles with minimum agglomeration. An energy storage density of 241 kWh/m3 (0.87 GJ/m3) and specific energy of 630 Wh/kg (2268 kJ/kg) was achieved with this material for 90% inlet relative humidity after a regeneration at 90 °C.

Metal oxide thin-film transistors are increasingly used in the driving backplanes of organic light-emitting diode displays. Commercial devices currently rely on metal oxides processed via physical vapour deposition methods, but the use of solution-based processes could provide a simpler, higher-throughput approach that would be more cost effective. However, creating oxide transistors with high carrier mobility and bias-stable operation using such processes has proved challenging. Here we show that transistors with high electron mobility (50 cm2 V−1 s−1) and operational stability can be fabricated from solution-processed multilayer channels composed of ultrathin layers of indium oxide, zinc oxide nanoparticles, ozone-treated polystyrene and compact zinc oxide. Insertion of the ozone-treated polystyrene interlayer passivates electron traps in the channel and reduces bias-induced instability during continuous transistor operation over a period of 24 h and under a high electric-field flux density (2.1 × 10−6 C cm−2). Furthermore, incorporation of the pre-synthesized aluminium-doped zinc oxide nanoparticles enables controlled n-type doping of the hybrid channels, providing additional control over the operating characteristics of the transistors.

GeTe Thermoelectrics

Cypermethrin, fenvalerate, permethrin, (S)‐α‐cyano‐3‐phenoxybenzyl (1R,cis)‐3‐(2, 2‐dibromovinyl)‐2, 2‐dimethylcyclopropanecarboxylate (NRDC 161) and (R,S)‐α‐cyano‐3‐phenoxybenzyl 2, 2,3, 3‐tetramethylcyclopropanecarboxylate (S‐3206; WL 41706) have been tested against adult mosquitoes (Anopheles stephensi) and tsetse flies (Glossina austeni). They possess many of the necessary characteristics such as high intrinsic toxicity, low volatility, and high stability but vary considerably in the contact action of their spray residues.

<p>Surveillance systems, both based on radio<br> frequencies (Radio Detection and Ranging: radar) and optical<br> signals (Light Detection and Ranging: lidar), are evolving toward<br> multiband multifunctional systems that are putting electronic<br> technologies under pressure. Thanks to its intrinsic high stability,<br> ultra-wide bandwidth, low loss propagation, EMI insensitivity,<br> and high frequency of the optical carrier, photonics can be<br> exploited not only for optical systems but also for facing these<br> new requirements in RF systems. In fact, microwave photonics<br> technologies play a crucial role in the generation of very stable<br> multi-band radiofrequency (RF) sources, and in very precise and<br> wideband RF signal detection and digitization, guaranteeing a<br> higher level of flexibility and reconfigurability, and the complete<br> software-defined configuration of radar systems. At the same<br> time they allow to implement multifrequency lidars able to<br> synthesize tunable RFs on optical carriers, for the exploitation of<br> RF radar techniques in lidar systems. Moreover solutions based<br> on integrated photonic circuits allow for a reduction of power<br> consumption and footprint thanks to the subsystems’<br> implementation on a chip.</p>

With the fast development of diverse electronics, the demand for safe energy storage systems with high energy density and high stability has increased rapidly. So far, lithium-ion batteries (LIBs) have dominated the market, from small smart electronics to electric vehicles. Nevertheless, LIBs have several limitations, such as high cost, limited raw material resources, high flammability, and harsh environmental impact. Therefore, novel rechargeable batteries which can mitigate these shortcomings must be explored. Aqueous zinc-ion batteries (ZIBs) have shown a promising future. Zinc with high theoretical volumetric capacity (5855 mAh cm-3) and high stability in aqueous electrolytes should enable high-performing, safe, and low-cost batteries. Additionally, the simple assembly of ZIBs in the ambient environment results in low capital costs. Despite these attractive merits, developing cathode materials with high capacity, rate performance, and stability in order to build commercial high-performing ZIBs, remains a great challenge.Cathode materials directly influence the electrochemical performance of ZIBs. Manganese oxide (MnO2) has been investigated as a promising cathode in ZIBs research due to its good specific capacity, low cost and high safety. However, the low ionic conductivity, slow diffusion kinetics, and low stability of MnO2 severely deteriorate the electrochemical performance and cycling stability of zinc-ion batteries. Recently, a series of studies have revealed the high effectiveness of coating on improving MnO2 cathode stability, including polymer coatings, carbon-based material coatings, artificial cathode-electrolyte interfaces, and metal oxide coatings.[1] Nevertheless, the improvement of other parameters, such as the rate performance, could be further improved for practical usage. In this research, we develop a novel modification method combining coating and doping strategies to induce MnO2 cathode with high capacity, high rate performance and low capacity decay after long-term operation. First, we utilize a facile one-step hydrothermal synthesis for Ag-doped α-MnO2. Different amounts of AgNO3 are added into reactors with KMnO4 and MnSO4 (n(Ag):n(Mn)=1:100-4:100) to investigate the influence of doping on capacity and rate performance. Subsequently, the doped tunnel-type MnO2 cathodes are mixed with precursor solutions of Al2O3 and then thoroughly stirred. Finally, an annealing process is conducted to achieve a nanoscale Al2O3 coating on the tunnel type MnO2. The coating configurations influence the electrochemical performance of cathodes;[2] thus, we test precursor solutions with different concentrations (1-3 wt% Al2O3) and annealing temperatures (500-700 °C) to investigate the influence of coating thickness and annealing treatment.With the assistance of scanning and transmission electron microscopes, the nanoscale Al2O3 layer coating on the doped active material is verified. The stable Al2O3 coating protects active materials from dissolution and structural collapse, improving cycling stability and resulting in high capacity retention after long-term operation. Moreover, a significant improvement in rate performance compared to unmodified MnO2 is verified through electrochemical tests. The X-ray photoelectron spectroscopy (XPS) and EPR spectra showed that the doped Ag+ ions lead to oxygen vacancies due to the formation of Ag-O-Mn.[3] The abundant vacancies act as active sites, significantly improving conductivity and ion insertion rates. The ex-situ X-ray diffractometer (XRD) and electrochemical tests are used to investigate the ion insertion mechanism during charging/discharging operations. The Ag-MnO2 @ Al2O3 cathode is synthesized through a facile methodology with environment-friendly materials. The modified cathode exhibits promising performance, especially regarding cycling stability and rate performance, which will be a crucial step for developing high-performing cathodes in aqueous zinc-ion batteries.Reference:[1] Shi, W., Lee, W. S. V., & Xue, J. (2021). Recent development of Mn‐based oxides as zinc‐ion battery cathode. ChemSusChem, 14(7), 1634-1658.[2] Zhou, A., Xu, J., Dai, X., Yang, B., Lu, Y., Wang, L., ... & Li, J. (2016). Improved high-voltage and high-temperature electrochemical performances of LiCoO2 cathode by electrode sputter-coating with Li3PO4. Journal of Power Sources, 322, 10-16.[3] Pu, X., Li, X., Wang, L., Maleki Kheimeh Sari, H., Li, J., Xi, Y., ... & Wu, Y. (2022). Enriching Oxygen Vacancy Defects via Ag–O–Mn Bonds for Enhanced Diffusion Kinetics of δ-MnO2 in Zinc-Ion Batteries. ACS Applied Materials & Interfaces, 14(18), 21159-21172. Figure 1

The preparation and characterization of gel-mixed matrix membranes (g-MMMs) with high CO2 permeability and stability performance

Metal – air battery chemistry defers by the electrolyte of choice. Zn – Air, Al – Air and Fe – Air batteries were already reported utilizing aqueous alkaline and brine solutions as electrolytes. The main advantage of these specific electrolyte of choice is theirs high ionic conductivity and the ability to efficiently reduce oxygen into hydroxide anions. Nevertheless, such batteries systems suffers from major drawbacks, such as comparably low voltage and specific energy, for Zn and Fe, and extremely high corrosion rates under open circuit condition, for Al. To deal with such challenges a fairly new approach has been taken. The approach is based on Room Temperature Ionic Liquids (RTIL) utilization as electrolyte in Metal – air batteries research. Among these, one could find Na –and Si – air battery systems. RTILs offer unique properties, while serving as electrolytic media. Among the properties one can count their low vapor pressure, even at considerably elevated temperatures, the high intrinsic ionic conductivity, non-flammability, thermal and chemical stability with considerably large electrochemical windows (in some cases as much as 5 V) what makes them remarkable electrolytes for high-end electrochemical applications. In our recent report[1], a new Al – air battery was presented applying 1-ethyl-3-methylimidazolium oligoflourohydrogenat (EMIm(HF)2.3F) RTIL. The specific conductivity of this exact stoichiometry is 100 mS cm-1 at 298 K, one the highest of all RTIL family, comparable to that of 0.5 M KCl aqueous solution. The presented novel Al – air battery can sustain current densities up to 1.5 mA cm-2, producing capacities above 140 mA h cm-2, and thus utilizing above 70% of the theoretical Al capacity. This is equivalent to outstanding energy densities of 2300 W h kg-1 and 6200 W h L-1. In the current work a further investigation of the RTIL based Al – air battery is presented. Combining surface characterization with electrochemical experiments, both in half cell and also a full battery discharge, an ongoing progress in the study of this unique battery is shown. One of the main achievements in the study is related to the understanding of the operation voltage drop (deep). Conditions for elimination of this voltage deep were established and will be reported. [1] D. Gelman, B. Shvartsev, Y. Ein-Eli, J. Mater. Chem. A. 2.47 (2014) 20237-20242.

The beta gamma-crystallin superfamily of eye lens proteins comprises a class of structurally related members with a wide variety of different functions. Common features of these proteins are 1. the Greek-key motif of antiparallel beta-sheets, called the crystallin fold, and 2. the high intrinsic long-term stability. Spherulin 3a (S3a), a dormant protein from the spherules of Physarum polycephalum, is the only known single-domain protein within the beta gamma-crystallin family. Based on sequence homology and 'domain swapping', it has been proposed to represent an evolutionary ancestor of present-day eye lens crystallins. Since S3a is highly expressed in spherulating plasmodia of P. polycephalum under a variety of stress conditions, it can be assumed that the protein may serve as a compatible solute in the cytosol of the slime mold. In order to investigate the stability and other physicochemical properties of a single-domain all-beta protein, we isolated natural S3a. For the large-scale purification, the recombinant protein was cloned and expressed in Escherichia coli. The detailed spectral and biochemical analysis proved the recombinant protein to be authentic. In its native form, S3a is dimeric. Due to its exposed cysteine residues (Cys4), in the absence of reducing agents intermolecular disulfide cross-linking leads to the formation of higher oligomers. In order to preserve the native quaternary structure without aggregation artifacts in denaturation/renaturation experiments, the Cys4-->Ser mutant (S3a C4S) was produced. Both the wild-type protein and its mutant are indistinguishable in their physicochemical properties. At pH 3 - 4, both proteins form a stable compact intermediate (A-state). Concentration-dependent thermal and chemical denaturation showed that the equilibrium unfolding of S3a obeys the simple two-state model with no significant occurrence of folding intermediates.

Controlled synthesis of nickel carbide nanoparticles and their application in lithium storage

Lithium titanate (LTO) is a promising candidate as an anode material in future generations of lithium ion batteries due to its high intrinsic safety and stability. In this work, we investigate the diffusion barriers for lithium ions in two different crystal structures of LTO using the density functional theory. Our calculations show that the activation barriers vary between 0.30--0.48 eV for the spinel phase ${\mathrm{Li}}_{4}{\mathrm{Ti}}_{5}{\mathrm{O}}_{12}$ and between 0.20--0.51 eV in the lithiated rocksalt phase ${\mathrm{Li}}_{7}{\mathrm{Ti}}_{5}{\mathrm{O}}_{12}$. The origins of the rather broad ranges of activation energies are related to different chemical environments of the diffusion channels due to mixed occupancies of some sites in LTO. Our results reveal that the determination of lithium diffusion constants in LTO can not be carried out by using a single activation barrier. Instead, the local environment of the diffusion paths must be considered to correctly capture the variety of activation barriers. Moreover, we find the sites which have mixed occupation in LTO to trap lithium vacancies in the spinel phase. This effect is not observed in the rocksalt phase. This behavior explains the low lithium diffusivity found in experiments for lithium concentrations in the vicinity of the spinel phase.

Biocatalysts play an important role in modern biotechnology because of their specificity, selectivity, efficiency and sustainability. One of the industrially most exploited and important groups of biocatalysts are the esterases. These enzymes catalyze, in the presence of water, the hydrolysis of an ester-bond resulting in the formation of an alcohol and a carboxylic acid. The use of enzymes in industrial processes also has its restrictions. Many processes are operated at elevated temperatures or in the presence of organic solvents. These conditions are detrimental to most enzymes and therefore there is a growing demand for enzymes with an improved stability. In this regard, there is a special interest from industry in enzymes of thermophilic origin since these enzymes generally display a high intrinsic thermal and chemical stability. This thesis describes the results of biochemical and structural analyses of thermostable esterases. Bioinformatics was used to identify new ester-hydrolyzing enzymes in the genomes of the hyperthermophilic bacterium Thermotoga maritima and the hyperthermophilic archaeon Archaeoglobus fulgidus. These potential esterases were cloned and heterologously expressed in Escherichia coli. Different types of ester hydrolyzing enzymes were found, including carboxylesterases, an acetyl esterase and a lipase. The biochemical properties of these enzymes were studied in detail. In addition, crystallization trials were performed, resulting in the three-dimensional structures of several of these enzymes. New structural features were revealed, such as the combination of an esterase domain with an immunoglobulin-like domain. The information obtained in this study provides fundamental knowledge, which may act as a basis for modern methods of enzyme engineering, with the aim to improve the applicability of these enzymes.

Heterogeneous Electro-Fenton catalysis with HKUST-1-derived Cu@C decorated in 3D graphene network.

Clusters with closed electronic shells are highlystable, and this is a robust property with far-reachingimplications for cluster abundance, cluster shapes, dynamicalresponse to electric fields and cluster dissociation. Clusterswith closed shells are also good candidates for the synthesis ofnovel materials. The density functional formalism is currentlyused to investigate the self-assembling of metallic clusters toyield cluster solids. A high intrinsic stability is not the onlyrequirement for expecting a successful assembling, and weinvestigate additional conditions by performing computersimulations for selected examples. The study of the assemblingof hydrogen-doped icosahedral aluminium clusters shows that anoptimized relative orientation of each cluster unit with respectto all its neighbour clusters becomes a favourable condition. Theanalysis of the clustering effects observed in crystallinealloys formed by Pb and alkali metals (tetrahedral Pb4clusters surrounded by the alkali cations form in those alloys)provides further insight: coating passivates the clusters andhelps to stabilize the assembled material.