Non-toxic Alternatives Research Articles

An alternative to the use of lead for patient treatment shielding in superficial radiotherapy.

Lead shielding is commonly used in the delivery of superficial radiotherapy albeit that the toxicity of this substance is of concern. The feasibility of using a non-toxic alternative, AttenuFlex™, is assessed using Xstrahl and Sensus treatment units. A series of lead and AttenuFlex™ circular cut outs and applicators were used with superficial beams (1.0-8.5mm Al HVL) to measure percentage depth dose (PDD), output factors (OF) and surface dose correction factors (DCF). X-ray transmission for each material was determined for each beam quality. For these measurements an Advanced Markus chamber either embedded within a virtual water phantom (PDD, OF, transmission) or placed on the surface of the phantom with entrance window downstream (DCF), was used. The depth of the phantom is 10cm for PDD and surface OF measurements. DCF(t) measurements were obtained with underlying lead or AttenuFlex™ at depth t = 0.1-10cm. Additionally, using EBT3 film fluorescent surface doses, to non-target tissue, due to underlying lead or AttenuFlex™ were compared.PDDs and OFs for both materials were within ± 1%. Lead and AttenuFlex™ transmission differences were clinically acceptable, all transmission values were < 5% and non-target doses were comparable. The variation of DCF(t) for lead and AttenuFlex™ exhibit a minima for all beams. In the minima region energy and applicator dependent differences between DCF(lead) and DCF(AttenuFlex™) are observed. These differences do not preclude the use of AttenuFlex™ as an alternative to lead in superficial therapy.

Charge transfer balancing of planar perovskite solar cell based on a low cost and facile solution-processed CuOx as an efficient hole transporting layer

Planar perovskite solar cells are known for their ease of fabrication and considerable efficiency. Hole transport layer in these cells is however mostly either expensive organic spiro-OMeTAD or hydrophilic PEDOT: PSS polymer which reduces cell lifespan due to its acidic nature. Copper oxide, on the other hand, is a non-toxic inorganic alternative. It can be synthesized through a facile solution-based process, requiring no vacuum system or N2 glovebox, which makes it conveniently adaptable to large-scale production. Inverted planar perovskite solar cells with CuOx as hole transport layer were studied. To balance the charge transfer in the device and avoid the charge accumulation in the bulk and interfaces, CuOx layer was deposited with different thicknesses. As verified by PL tests, quenching of the deposited CuOx layer was comparable to PEDOT: PSS layer which signifies its effectiveness as a hole transport layer. Optimum observed results were for a cell with an efficiency of 6.26%, Voc of 0.71 V, Jsc of 12.87 mA/cm2, and fill factor of 0.69. Consistent with J–V measurements, electrochemical impedance spectroscopy indicated a significant increase in charge transport resistance between hole transport layer and perovskite film as the CuOx film thickness was increased from 55 nm to 75 nm.

Ecofriendly Synthesis of Silver Nanoparticles Using Aqueous Extracts of Zingiber officinale (Ginger) and Nigella sativa L. Seeds (Black Cumin) and Comparison of Their Antibacterial Potential

Applications of chemical synthetic methods for the preparation of metal nanoparticles involve toxic reagents, which are hazardous to both humans and the environment. On the other hand, ecofriendly plant-based techniques offer rapid, non-toxic, and suitable alternatives to the traditional methods. Herein, we report an eco-friendly method for the preparation of silver nanoparticles (Ag NPs) using two different aqueous extracts of Zingiber officinale (ginger) and Nigella sativa L. seeds (black cumin). Successful preparation of Ag NPs was confirmed by X-ray diffraction, ultraviolet–visible (UV-Vis) spectroscopy, and energy dispersive spectroscopy (EDX). Transmission electron microscopy (TEM) analysis revealed that Nigella sativa L. seed extract (NSE) produced a smaller size of NPs (~8 nm), whereas the ginger extract (GE) led to the formation of slightly larger Ag NPs (~12 nm). In addition, to study the effect of concentration of the extract on the quality of resulting NPs, two different samples were prepared from each extract by increasing the concentrations of the extracts while using a fixed amount of precursor (AgNO3). In both cases, a high concentration of extract delivered less agglomerated and smaller-sized Ag NPs. Furthermore, the antibacterial properties of as-prepared Ag NPs were tested against different bacterial strains. Notably, despite the slightly better quality of Ag NPs obtained from NSE (NSE-Ag), NPs prepared by using GE (GE-Ag) demonstrated superior antibacterial properties. In case of the plant-extract-based synthesis of nanoparticles, it is widely reported that during the preparation, the residual phytomolecules remain on the surface of resulting NPs as stabilizing agents. Therefore, in this case, the high antibacterial properties of GE-Ag can be attributed to the contributing or synergetic effect of residual phytomolecules of GE extract on the surface of Ag NPs, since the aqueous extract of GE has been known to possess higher intrinsic bactericidal properties when compared to the aqueous NSE extract.

(Keynote) Band-Edge Emission from AgInS2/Ga2S3 Core/Shell Quantum Dots and Enhancement of Their Quantum Yield

Semiconductor nanoparticles, diameter of which is 10 nm or less possess fascinate optical properties due to quantum confinement, causing, for instance, an increase in the band gap energy with decrease in the particle size that is called the quantum size effect. In case of semiconductor nanoparticles that emit photoluminescence (PL), their particle size determines the PL color. In other words, multiply color PL agents are producible from one kind of semiconductor. Such the fascinate optical properties were found mainly in II-VI semiconductors and they have been extensively studied as quantum dots (QDs). In particular, CdSe nanoparticles that became the first commercial products as QDs and the narrow band-edge emission from that materials attracts intense attention because they are one of ideal light sources for fabricating brilliant color displays. In fact, liquid-crystal displays including QDs backlights were on sale but they were discontinued because CdSe and related QDs containing toxic elements faced a ban in many countries. It was, therefore, necessary to search for non-toxic alternatives possessing comparable optical properties.In 2007, we have published a paper regarding the first luminescent I-III-VI ternary semiconductor QDs that are AgInS2 QDs. In addition, if ZnS and AgInS2 are alloyed, PL color is tunable by particle size as well as composition ratio of ZnS and AgInS2.[1] However, although the quantum yield (QY) of the obtained PL was as high as 80%,[2] the spectra was relatively broad with large width as shown by (1) in Fig 1, indicating that the PL was emitted from defect sites of the particles. Since it is quite natural to suppose that possibility of defect site generation in ternary semiconductor is much higher than that in binary semiconductor like CdSe, it was, then, thought to be difficult or impossible to eliminate the defect sites from the I-III-VI semiconductor QDs. Nevertheless, we made several attempts and significant achievements as presented in this paper were obtained.Modification of QDs with a shell material having wide band-gap is typical way to eliminate defect sites. ZnS is a frequently utilized but this is not appropriate because above-mentioned alloying reaction occurs between ZnS and I-III-VI semiconductor. Similarly, other materials that are often used as shell were useless. Then, we explored other materials that have never been employed as a shell material for QDs. One of them was In2S3 because the phase diagram predicted that this semiconductor and AgInS2 did not melt in each other. Then, PL spectrum of the prepared AgInS2/In2S3 QDs showed not only broad PL but also narrow PL peak that was located at shorter wavelength than the former, as shown by (2) in Fig. 1. Furthermore, when Ga2S3 having larger bandgap energy than In2S3 was chosen as a shell material, as shown by (3) in Fig. 1, the broad PL was almost suppressed, whereas the narrow PL peak distinctly appeared. However, QY of the narrow PL was as low as 29%, implying that defect sites causing non-radiative recombination were still remained.The first breakthrough to remove most of defect sites was found when tri-n-octylphosphine was added to the QDs solution, as shwon by (4) in Fig. 1, that exhibited 56.0% of QY. [3] In order to remove defect sites generated in the interior of the AgInS core, we are now changing the way to synthesize AgInS2 core. Change of S source from thiourea to dimethylthiourea was effective because the latter species had higher solubility in the solvent we used, enabling slow reaction with dropwise of the S source. The resulting AgInS2/Ga2S3 core/shell QDs gave only narrow PL with 73.2% of QY. [4] References [1] T. Torimoto, S. Kuwabata, et al., J. Am. Chem. Soc., 2007, 129, 12388-12389.[2] T. Torimoto, S. Kuwabata, et al., Chem. Commun, 2010, 46, 2082-2084.[3] T. Uematsu, S. Kuwabata, et al., NPG Asia Mater. 2018, 10, 713-726.[4] W. Hoisang, T. Uematsu, S. Kuwabata, et al., Nanomaterials, 2019, 9, 1763. Figure 1

Inside Back Cover: Next Generation of Zinc Bisguanidine Polymerization Catalysts towards Highly Crystalline, Biodegradable Polyesters (Angew. Chem. Int. Ed. 48/2020)

Many bioplastics are produced by metal-catalyzed ring opening polymerization. For a truly sustainable lifecycle the industrially used cytotoxic catalyst tin(II)-2-ethylhexanoate must be replaced by non-toxic alternatives. In their Research Article on page 21778, L. Hartmann, S. Herres-Pawlis, and co-workers report the fastest known robust catalyst for the polymerization of lactide (LA) and ϵ-caprolactone (CL). This zinc guanidine catalyst polymerizes technical LA and CL in the melt with high rate constants and molar masses, giving a colorless, transparent polymer.

Next Generation of Zinc Bisguanidine Polymerization Catalysts towards Highly Crystalline, Biodegradable Polyesters.

Polylactide and polycaprolactone are both biodegradable polymers produced through metal‐catalyzed ring‐opening polymerization. For a truly sustainable lifecycle of these polymers it is essential to replace the industrially used cytotoxic catalyst tin(II) bis(2‐ethylhexanoate) [Sn(Oct)2] with non‐toxic alternatives. Here, we report the fastest known robust catalyst in the polymerization of lactide and ϵ‐caprolactone. This zinc guanidine catalyst can polymerize non‐purified technical rac‐lactide and ϵ‐caprolactone in the melt at different [M]/[I] ratios with fast rate constants, high molar masses, and high yields in a short time, leading to colorless, transparent polymer. Moreover, we report that polylactide and polycaprolactone produced by zinc‐guanidine complexes have favorably high crystallinities. In fact, the obtained polylactide shows a more robust degradation profile than its Sn(Oct)2‐catalysed equivalent due to a higher degree of crystallinity.

Lead-Free Antimony Halide Perovskite with Heterovalent Mn2+ Doping.

Lead toxicity is hindering the applications of conventional lead halide perovskites (PVKs), and antimony (Sb) is a promising nontoxic Pb alternative, showing huge potential in optoelectronic devices. Herein, pure and Mn-doped Cs3Sb2Cl9 crystals are synthesized in a facile route and studied both experimentally and theoretically. All the pure and Mn-doped Cs3Sb2Cl9 crystals show good crystallinity and similar crystal structures, exhibiting visible photoluminescence (PL) characteristics with emission peaks at 422 and 613 nm, respectively. Combined density functional theory (DFT) calculations and experimental analyses reveal that the structure of the host PVK compound Cs3Sb2Cl9 is not influenced by the formation of [MnCl6]4- octahedra and that Mn 3d orbitals generate impurity states in the forbidden energy gap of Cs3Sb2Cl9. Therefore, energy transfer from Cs3Sb2Cl9 to Mn 3d states is observed, resulting in the d-d transition and bright red luminescence. Mn-doped Sb-based PVK can be utilized as a new platform for optoelectronic applications.

Defect and interface engineering of highly efficient La2NiMnO6 planar perovskite solar cell: A theoretical study

Abstract To be able to efficiently convert solar energy to electrical energy an in depth understanding of the working mechanism of the perovskite solar cell is indispensable. In this theoretical study, the factors which govern the losses associated with the active double perovskite material have been explored in detail. La2NiMnO6 has been proposed as inorganic, non-toxic alternatives to replace the conventional lead halide mixed organic-inorganic material. Interestingly, the results of the computation reveal that passivation of the trap states inside the La2NiMnO6 material is more important than interfacial defect passivation. Also the interfacial property of electron transport material/absorber interface is critical in achieving a high efficiency device. Capacitance-frequency analysis has been performed demonstrating how interface and defect passivation strengthens the recombination resistance of the cell. Furthermore it was established that an efficiency yield of over 22% can be achieved if the absorber layer thickness was suitably chosen. Finally based on the derived value of ideality factor, the exact reason for the loss in open circuit voltage of the cell could be deduced.

High‐throughput computational design of halide perovskites and beyond for optoelectronics

AbstractHalide perovskites have attracted great interest as promising next‐generation materials in optoelectronics, ranging from solar cells to light‐emitting diodes. Despite their exceptional optoelectronic properties and low cost, the prototypical organic–inorganic hybrid lead halide perovskites suffer from toxicity and low stability. Therefore, it is of high demand to search for stable and nontoxic alternatives to the hybrid lead halide perovskites. Recently, high‐throughput computational materials design has emerged as a powerful approach to accelerate the discovery of new halide perovskite compositions or even novel compounds beyond perovskites. In this review, we discuss how this approach discovers halide perovskites and beyond for optoelectronics. We first overview the background of halide perovskites and methodologies in high‐throughput computational design. Then, we focus on materials properties for different optoelectronic applications, and how they are assessed with materials descriptors. Finally, we review different studies in terms of specific materials types to discuss their design principles, screening results, and experimental verification.This article is categorized under: Structure and Mechanism &gt; Computational Materials Science Electronic Structure Theory &gt; Density Functional Theory

Fabrication and Characterization of Flexible Three-Phase ZnO-Graphene-Epoxy Electro-Active Thin-Film Nanocomposites: Towards Applications in Wearable Biomedical Devices

Perovskite oxides have been used as sensors, actuators, transducers, for sound generation and detection, and also in optical instruments and microscopes. Perovskite halides are currently considered as optoelectronic devices such as solar cells, photodetectors, and radiation detection, but there are major issues with stability, interfacial recombination, and electron/hole mobility. The following work looks into the fabrication of non-toxic ZnO-based lead-free alternatives to perovskite oxides for use as secondary sensors or electron transport layers along with perovskite halides for application in stacked biomedical wearable devices. Three-phase, lead-free, Zinc Oxide-Graphene-Epoxy electroactive nanocomposite thin films were fabricated. The volume fraction of the Graphene phase was held constant at 10%, while the volume fraction of the ZnO phase was varied from 10–70%. The dielectric constant, capacitance, impedance, resistance, and conductance of the samples were measured using an impedance analyzer, and the results were compared as a function of volume fraction of ZnO to understand the electron transport performance of these thin films. The impedance and dielectric spectra of the nanocomposites were recorded over a frequency range of 20 Hz to 10 MHz. The microstructural properties and cross-section of the thin films were analyzed using a Scanning Electron Microscope. The high sensitivity and electron transport properties of the composite could be potentially utilized in biomedical devices at low- and high-frequency ranges.

Using GPS and accelerometry data to study the diet of a top avian scavenger

ABSTRACT Capsule The Eurasian Griffon Vulture Gyps fulvus is an obligate scavenger relying on spatially and temporally unpredictable food resources. We demonstrate how high-frequency telemetry data can be efficiently used to identify vultures’ feeding locations in the wild and study their diet. Aims To study the Griffon Vulture diet composition, seasonal variations, and bathing frequency in an area with high natural food availability. Methods We used a remote-sensing technique based on GPS and accelerometry data to identify the feeding locations, and ground-truthing to identify the carcass species and investigate the causes of mortality. Results We identified 13 taxa in the diet of Griffon Vultures. Cattle comprised 48.5% of the diet, followed by sheep (24.3%), while wild animals were 13.1%. We observed seasonal variation in the proportion of small stock and game species in the diet. Predation was reported as the main cause of mortality (60.2%) for prey species, while natural causes accounted for 37.6%. Vultures were mainly feeding in areas south of their breeding colonies in Bulgaria and Greece. Natural springs and fountains were regularly used by the Griffon Vultures for bathing and drinking, especially in the summer. Conclusions Free-ranging livestock creates favourable feeding conditions for vultures, especially in areas with rugged terrain and a high density of predators. An increase in the number of wild ungulates can potentially buffer the fluctuations in livestock numbers and be beneficial for vultures, especially in the autumn and winter months. Lead ammunition must be substituted with non-toxic alternatives to reduce the exposure of vultures and other scavengers to lead poisoning.

K2CuX3 (X = Cl, Br): All-Inorganic Lead-Free Blue Emitters with Near-Unity Photoluminescence Quantum Yield

Recently, copper(I) halides have been gaining increased attention as highly luminescent nontoxic alternatives to lead halide perovskites for optoelectronic applications. Here, we report preparation...

A Potential Checkmate to Lead: Bismuth in Organometal Halide Perovskites, Structure, Properties, and Applications.

The remarkable optoelectronic properties and considerable performance of the organo lead‐halide perovskites (PVKs) in various optoelectronic applications grasp tremendous scientific attention. However, the existence of the toxic lead in these compounds is threatening human health and remains a major concern in the way of their commercialization. To address this issue, numerous nontoxic alternatives have been reported. Among these alternatives, bismuth‐based PVKs have emerged as a promising substitute because of similar optoelectronic properties and extended environmental stability. This work communicates briefly about the possible lead‐alternatives and explores bismuth‐based perovskites comprehensively, in terms of their structures, optoelectronic properties, and applications. A brief description of lead‐toxification is provided and the possible Pb‐alternatives from the periodic table are scrutinized. Then, the classification and crystal structures of various Bi‐based perovskites are elaborated on. Detailed optoelectronic properties of Bi‐based perovskites are also described and their optoelectronic applications are abridged. The overall photovoltaic applications along with device characteristics (i.e., V OC, J SC, fill factor, FF, and power conversion efficiency, PCE), fabrication method, device architecture, and operational stability are also summarized. Finally, a conclusion is drawn where a brief outlook highlights the challenges that hamper the future progress of Bi‐based optoelectronic devices and suggestions for future directions are provided.

Setting maximum levels for lead in game meat in EC regulations: An adjunct to replacement of lead ammunition

Each year, hunters from 12 of the 27 European Union (EU) countries and the UK shoot over 6 million large game mammals, 12 million rabbits and hares and over 80 million birds. They support an international game meat market worth over 1.1 thousand million Euros. Animals shot with lead ammunition frequently contain lead fragments in the carcass which contaminate meals made from game meat with concentrations of lead substantially above the maximum allowable level (ML) set by European Commission Regulation EC1881/2006 for meat from domesticated animals. This poses a health risk to frequent consumers of wild-shot game meat, with children and pregnant women being particularly vulnerable. Total replacement of lead rifle and shotgun ammunition with available non-toxic alternatives is needed for all hunting in EU nations to prevent exposure of humans and wildlife to ammunition-derived lead and to allow the depletion of the long-term environmental legacy of lead from spent ammunition. We propose that EC1881/2006 is amended to incorporate an ML for game meats as a supplementary measure to the replacement of lead ammunition. This would harmonise food safety standards for lead in meats traded across and imported into the EU.

Monitoring biofouling as a management tool for reducing toxic antifouling practices in the Baltic Sea

Over two million leisure boats use the coastal areas of the Baltic Sea for recreational purposes. The majority of these boats are painted with toxic antifouling paints that release biocides into the coastal ecosystems and negatively impact non-targeted species. Regulations concerning the use of antifouling paints differ dramatically between countries bordering the Baltic Sea and most of them lack the support of biological data. In the present study, we collected data on biofouling in 17 marinas along the Baltic Sea coast during three consecutive boating seasons (May–October 2014, 2015 and 2016). In this context, we compared different monitoring strategies and developed a fouling index (FI) to characterise marinas according to the recorded biofouling abundance and type (defined according to the hardness and strength of attachment to the substrate). Lower FI values, i.e. softer and/or less abundant biofouling, were consistently observed in marinas in the northern Baltic Sea. The decrease in FI from the south-western to the northern Baltic Sea was partially explained by the concomitant decrease in salinity. Nevertheless, most of the observed changes in biofouling seemed to be determined by local factors and inter-annual variability, which emphasizes the necessity for systematic monitoring of biofouling by end-users and/or authorities for the effective implementation of non-toxic antifouling alternatives in marinas. Based on the obtained results, we discuss how monitoring programs and other related measures can be used to support adaptive management strategies towards more sustainable antifouling practices in the Baltic Sea.

One-Pot Multicomponent Reaction of Catechols, Ammonium Acetate, and Aldehydes for the Synthesis of Benzoxazole Derivatives Using the Fe(III)-Salen Complex.

The Fe(III)-salen complex has been applied successfully as a catalyst for the novel, simple, efficient, and one-pot multicomponent synthesis of benzoxazole derivatives from catechols, ammonium acetate as the nitrogen source, and aldehydes (nontoxic and cheap alternatives of amines) for the first time. Using this procedure, a wide range of benzoxazoles was successfully synthesized in the presence of a catalyst in EtOH under mild conditions, and all products were obtained in excellent yields. To the best of our knowledge, this method is the first example of the multicomponent synthesis of benzoxazole derivatives using these starting materials. The notable features such as the use of air that is considered as a benign oxidant and EtOH as a green solvent, ease of product separation, readily available and inexpensive aldehydes, and mild conditions make our procedure more efficient and practical for organic synthesis. Moreover, the current protocol is successfully applied to synthesize desirable products on a large scale.

Bioderived Molecular Electrodes for Next-Generation Energy-Storage Materials.

Nature-derived organic small molecules, as energy-storage materials, provide low-cost, recyclable, and non-toxic alternatives to inorganic and polymer electrodes for lithium-/sodium-ion batteries and beyond. Some organic carbonyl compounds have met or exceeded the voltages and gravimetric storage capacities achieved by traditional transition metal oxide-based compounds due to the metal-ion coupled redox and facile electron-transport capability of functional groups. Stability issues that previously limited the capacity of small organic molecules can be remediated with reactions to form insoluble salts, noncovalent interactions (hydrogen bonding and π stacking), loading onto substrates, and careful electrolyte selection. The cost-effectiveness and sustainability of organic materials may further be improved by employing porphyrin-based electrodes and multivalent-ion batteries utilizing abundant metals, such as aluminum and zinc. Finally, redox flow batteries take advantage of the solubility of organics for the development of scalable, high power density, and safe energy-storage devices based on aqueous electrolytes. Herein, the advantages and prospects of small molecule-based electrodes, with a focus on nature-derived organic and biomimetic materials, to realize the next-generation of green battery chemistry are reviewed.

Nanoparticles of selenium as high bioavailable and non-toxic supplement alternatives for broiler chickens.

Selenium is commonly used in the poultry industry as an additive in broiler feed to improve immunity and overall health. The selenium comes in different forms, inorganic and organic selenium, as sodium selenite and selenomethionine, respectively. This study proposes the use of nanoparticles of selenium (nanoSe) for improved delivery and absorption of the trace element while causing no toxicity. Previous studies have shown the success in utilizing nanoSe in broiler feed, with increased absorption and diffusion of material into organs and tissues, and increased antioxidant capacity. However, the mechanism of nanoSe conversion remains unknown, and the gut microbiota is believed to play a significant role in the process. The use of inorganic selenium in poultry feed demonstrated a lower bioavailability in breast (P ≤ 0.01) and duodenum tissue (P ≤ 0.05), and increased accumulation in organs involved in detoxification processes as compared to organic selenium and selenium nanoparticle supplementation. Histopathological analysis showed that nanoSe did not cause any damaging effects to the tissues analysed, revealing intact epithelial cells in the digestive system and neuronal bodies in brain tissue. The results indicate that nanoparticles of selenium operate a similar way to organic selenium and could potentially be used in poultry feed as a trace element additive.

Electronic Structure and Optoelectronic Properties of Bismuth Oxyiodide Robust against Percent‐Level Iodine‐, Oxygen‐, and Bismuth‐Related Surface Defects

AbstractIn the search for nontoxic alternatives to lead‐halide perovskites, bismuth oxyiodide (BiOI) has emerged as a promising contender. BiOI is air‐stable for over three months, demonstrates promising early‐stage photovoltaic performance and, importantly, is predicted from calculations to tolerate vacancy and antisite defects. Here, whether BiOI tolerates point defects is experimentally investigated. BiOI thin films are annealed at a low temperature of 100 °C under vacuum (25 Pa absolute pressure). There is a relative reduction in the surface atomic fraction of iodine by over 40%, reduction in the surface bismuth fraction by over 5%, and an increase in the surface oxygen fraction by over 45%. Unexpectedly, the Bi 4f7/2 core level position, Fermi level position, and valence band density of states of BiOI are not significantly changed. Further, the charge‐carrier lifetime, photoluminescence intensity, and the performance of the vacuum‐annealed BiOI films in solar cells remain unchanged. The results show BiOI to be electronically and optoelectronically robust to percent‐level changes in surface composition. However, from photoinduced current transient spectroscopy measurements, it is found that the as‐grown BiOI films have deep traps located ≈0.3 and 0.6 eV from the band edge. These traps limit the charge‐carrier lifetimes of BiOI, and future improvements in the performance of BiOI photovoltaics will need to focus on identifying their origin. Nevertheless, these deep traps are three to four orders of magnitude less concentrated than the surface point defects induced through vacuum annealing. The charge‐carrier lifetimes of the BiOI films are also orders of magnitude longer than if these surface defects were recombination active. This work therefore shows BiOI to be robust against processing conditions that lead to percent‐level iodine‐, bismuth‐, and oxygen‐related surface defects. This will simplify and reduce the cost of fabricating BiOI‐based electronic devices, and stands in contrast to the defect‐sensitivity of traditional covalent semiconductors.

Amino Acids: Nontoxic and Cheap Alternatives for Amines for the Synthesis of Benzoxazoles through the Oxidative Functionalization of Catechols

AbstractThe nano magnetic Fe3O4 (NM−Fe3O4) was applied for the synthesis of benzoxazoles via a C(aryl)−OH functionalization of catechol derivatives and amines in ethanol at room temperature. In the next step, amino acids have been applied as nontoxic and cheap alternatives for amines. The obtained products were similar with the regular amines case. This is the first report about the application of amino acids as alternatives for primary amines in organic synthesis. Furthermore, the presented method was successfully applied toward the synthesis of desired products in large scales.magnified image