Synthetic Conditions Research Articles

Structural Design and Energy and Environmental Applications of Hydrogen-Bonded Organic Frameworks: A Systematic Review.

Hydrogen-bonded organic frameworks (HOFs) are emerging porous materials that show high structural flexibility, mild synthetic conditions, good solution processability, easy healing and regeneration, and good recyclability. Although these properties give them many potential multifunctional applications, their frameworks are unstable due to the presence of only weak and reversible hydrogen bonds. In this work, the development history and synthesis methods of HOFs are reviewed, and categorize their structural design concepts and strategies to improve their stability. More importantly, due to the significant potential of the latest HOF-related research for addressing energy and environmental issues, this work discusses the latest advances in the methods of energy storage and conversion, energy substance generation and isolation, environmental detection and isolation, degradation and transformation, and biological applications. Furthermore, a discussion of the coupling orientation of HOF in the cross-cutting fields of energy and environment is presented for the first time. Finally, current challenges, opportunities, and strategies for the development of HOFs to advance their energy and environmental applications are discussed.

Hybrid Nickel‐Copper Oxide Nanoparticles: A Multiparametric Study for the Influence of Synthetic Parameters on the Optical and Physical Properties

AbstractThe hybrid nanoparticles of nickel and copper oxide are optimized by varying synthetic conditions such as precursor salt concentration, rate of reagent addition, pH, and temperature. The resulting nanoparticles are characterized by using UV‐Visible and fluorescence spectroscopy, hydrodynamic size, zeta potential, polydispersity index, SEM, EDX, XRD, and FTIR spectroscopy. The control over composition and physical properties of these hybrid oxides are analyzed through careful variations in the synthetic parameters. UV‐Vis analysis demonstrated the successful synthesis of NiO‐CuO hybrid nanoparticles at various concentrations. NiO dominant hybrids are obtained by quick addition of the reagent and at higher pH, while CuO dominant hybrids require slower addition of reagent and lower pH. The increase in the temperature causes a hypochromic shift in the UV‐Vis absorption, whereas fluorescence is enhanced with increase in the CuO concentration. The fluorescence generally remained stable by varying time of reagent addition, pH, and temperature. More stable and least‐sized NiO‐CuO hybrid nanoparticles are obtained at ratios of 75 : 25 and 25 : 75, by quick addition of reagent, at higher pH levels, and at higher temperatures. A better understanding of their physical and optical properties obtained by varying synthetic parameters may potentially result in their enhanced applications.

Tuning Surface, Phase, and Magnetization of Superparamagnetic Magnetite by Ionic Liquids: Single-Step Microwave-Assisted Synthesis.

Achieving colloidal and chemical stability in ferrofluids by surface modification requires multiple steps, including purification, ex situ modification steps, and operation at high temperatures. In this study, a single-step microwave-assisted methodology is developed for iron oxide nanoparticle (IONP) synthesis utilizing a series of imidazolium-based ionic liquids (ILs) with chloride, bis(trifluoromethylsulfonyl)imide, and pyrrolide anions as the reaction media, thus eliminating the use of volatile organics while enabling rapid synthesis at 80 °C as well as in situ surface functionalization. The characterized surface functionality, hydrodynamic particle size, magnetization, and colloidal stability of the IONPs demonstrate a strong dependence on the IL structure, ion coordination strength, reactivity, and hydrophilicity. The IONPs present primarily a magnetite (Fe3O4) phase with superparamagnetism with the highest saturation magnetization at 81 and 73 emu/g at 10 and 300 K, respectively. Depending on the IL coating, magnetization and exchange anisotropy decrease by 20 and 2-3 emu/g (at 35 wt % IL), respectively, but still represent the highest magnetization achieved for coated IONPs by a coprecipitation method. Further, the surface-functionalized superparamagnetic magnetite nanoparticles show good dispersibility and colloidal stability in water and dimethyl sulfoxide at 0.1 mg/mL concentration over the examined 3 month period. This study reports on the intermolecular and chemical interactions between the particle surface and the ILs under synthetic conditions as they relate to the magnetic and thermal properties of the resulting IONPs that are well suited for a variety of applications, including separation and catalysis.

Research on Brake Energy Recovery Strategy Based on Working Condition Identification

As a transitional vehicle between fuel and electric vehicles, hybrid vehicles achieve energy savings and emission reductions without range anxiety. Regenerative braking has a direct impact on the fuel consumption of the whole vehicle; however, the current regenerative braking strategy for commercial vehicles is not yet perfect and has a poor adaptability in terms of working conditions and whole-vehicle load changes. Therefore, this paper proposes a regenerative braking strategy based on the identification of working conditions, by considering the influence of the vehicle load state and driving conditions on braking. Firstly, historical driving data of commercial vehicles were obtained from GPS data, driving conditions were classified using principal component analysis (PCA) and K-means, and a working condition recogniser was constructed using a back propagation neural network (BPNN) optimised with the Coati optimisation algorithm (COA). The recognition accuracy of the COA-BPNN was 7.6% better than that of the BPNN. Secondly, front and rear axle braking force distribution strategies are proposed, according to the braking intensity magnitude and load state under empty-, half-, and full-load conditions. Finally, a genetic algorithm (GA) was used to find the optimal control parameters for each category of working conditions, and the COA-BPNN condition recogniser identified the current category of working conditions needed to retrieve the corresponding optimal control parameters in the offline parameter library. The simulation results under C-WTVC and synthetic conditions show that the energy recovery rate of the proposed strategy in this paper reached up to 69.65%, which is at most 206.3% higher than that of the fixed-ratio strategy and at most 37.4% higher than that of the fuzzy control strategy.

Abundance of Low-Energy Oxygen Vacancy Pairs Dictates the Catalytic Performance of Cerium-Stabilized Zirconia.

Cerium-stabilized zirconia (Ce1-xZrxOy, CZO) is renowned for its superior oxygen storage capacity (OSC), a key property long believed to be beneficial to catalytic oxidation reactions. However, 50% Ce-containing CZO recorded with the highest OSC has disappointingly poor performance in catalytic oxidation reactions compared to those with higher Ce contents but lower OSC ability. Here, we employ global neural network (G-NN)-based potential energy surface exploration methods to establish the first ternary phase diagram for bulk structures of CZO, which identifies three critical compositions of CZO, namely, 50, 60, and 80% Ce-containing CZO that are thermodynamically stable under typical synthetic conditions. 50% Ce-containing CZO, although having the highest OSC, exhibits the lowest O vacancy (Ov) diffusion rate. By contrast, 60% Ce-containing CZO, despite lower OSC (33.3% OSC compared to that of 50% Ce-containing CZO), reaches the highest Ov diffusion ability and thus offers the highest CO oxidation catalytic performance. The physical origin of the high performance of 60% Ce-containing CZO is the abundance of energetically favorable Ov pairs along the ⟨110⟩ direction, which reduces the energy barrier of Ov diffusion in the bulk and promotes O2 activation on the surface. Our results clarify the long-standing puzzles on CZO and point out that 60% Ce-containing CZO is the most desirable composition for typical CZO applications.

A graded structure of silicon/carbon composite powder for highly stable lithium ion battery anode

Silicon has much higher theoretical specific capacity than traditional graphite materials (3579 mAh g−1vs. Graphite: 372mAh g−1). However huge volumetric expansion (∼300%) of silicon seriously reduces its cyclic stability as anode in lithium-ion batteries. Though reduce the size of silicon based composites to nanoscale and tuning their porosity have been extensively studied, above strategies reduce the vibration density of the anode material unsurprisingly, which is not conducive to the advantage of high volumetric capacity anode. In this work, we design a unique graded silicon/carbon powder to maintain excellent energy storage performance at high vibration density. The composite of graded structure is constructed by first particles and second particles. The construction strategy is proved to be adoptable to achieve cost effective production of high performance silicon/carbon composite anode for development of advanced lithium-ion battery. Under the premise of industrial powder materials’ production technologies, a graded structure silicon/carbon composite with optimized synthetic condition shows high-reversible capacity of 827.4 mAh g−1 at 200 mAh g−1 (equal to 1464.5 Ah L−1) and it capacity remains at 715.0 mAh g−1 after 800 cycles, with a capacity retention rate of 86.37%, which shows high cycle life.

Hydrazine-Assisted Synthesis, Structures, Photoelectricity, and Photocatalysis of Ternary Mercury-Tellurostannate Hybrids with Transition-Metal Complexes.

Tellurostannates are traditionally prepared by multistep reactions using the tellurides SnTe, SnTe2, K4SnTe4, or A6SnTe6 (A = K, Rb, or Cs) as precursors, which are usually prepared by the molten reaction of alkali metals Sn and Te under harsh synthetic conditions. Differently, ternary Hg-tellurostannate hybrids [Mn(en)3]HgSnTe3(Te2) (1) (en = ethylenediamine), [Mn(dien)2]HgSnTe3(Te2) (2), and [Fe(dien)2]HgSnTe3(Te2) (3) (dien = diethylenetriamine) were synthesized by one-pot reactions using Sn and Te powders as starting materials in the presence of hydrazine under mild solvothermal conditions. In 1, HgTe3 and SnTe4 units are joined via Te-sharing to form a 1-D polymeric chain [HgSnTe3(Te2)]n2n-, while the [HgSnTe3(Te2)]n2n- chains in 2 and 3 are composed of HgTe4 and SnTe4 units. The common feature of the [HgSnTe3(Te2)2-]n chains in 1-3 is that they are constructed by both the telluride anion Te2- and the polytelluride anion Te22-. 1-3 exhibited strong photocurrent responses with current densities of 5.26, 3.38, and 3.94 μA cm-2, respectively. They showed effective photocatalytic activities for methylene blue degradation with degradation ratios in the range of 85.3-94.6% after light irradiation for 80 min. Investigation of the photocatalytic mechanism showed that •O2- radicals and h+ holes were the main active substances in the photodegradation.

Interfacial polymerization of self-standing ABC-stacking Covalent organic framework membranes for dye separation

Covalent organic framework (COF)-based membranes are burgeoning candidates for separation technologies owing to their well-ordered channel structures. However, it is still a significant challenge to obtain high-quality COF membranes with a mild and convenient preparation strategy. In this paper, we adopted a simple liquid-liquid interfacial polymerization method to manufacture a self-standing COF membrane with decent crystallinity at room temperature. Aldehyde monomer and catalyst were dissolved in water as the bottom layer and the amine monomer was dissolved in ethyl acetate as the top layer, and new COF membranes were subsequently obtained by interfacial polymerization in the two-phase interface. The synthetic conditions including precursor and catalyst dosage were further optimized, and thus-synthesized PDA-TAPB-ABC membrane displayed a stable rejection to MB of 97.57% with a high water permeance of up to 101. 32 L m−2h−1bar−1. Its dyes separation performance was much better than their AA-stacking counterpart. Moreover, the prepared membrane endowed favorable chemical stability and long-term durability.

The Overlooked Potential of Sulfated Zirconia: Reexamining Solid Superacidity Toward the Controlled Depolymerization of Polyolefins.

Closed-loop recycling via an efficient chemical process can help alleviate the global plastic waste crisis. However, conventional depolymerization methods for polyolefins, which compose more than 50% of plastics, demand high temperatures and pressures, employ precious noble metals, and/or yield complex mixtures of products limited to single-use fuels or oils. Superacidic forms of sulfated zirconia (SZrO) with Hammet Acidity Functions (H0) ≤ - 12 (i.e., stronger than 100% H2SO4) are industrially deployed heterogeneous catalysts capable of activating hydrocarbons under mild conditions and are shown to decompose polyolefins at temperatures near 200 °C and ambient pressure. Additionally, confinement of active sites in porous supports is known to radically increase selectivity, coking and sintering resistance, and acid site activity, presenting a possible approach to low-energy polyolefin depolymerization. However, a critical examination of the literature on SZrO led us to a surprising conclusion: despite 40 years of catalytic study, engineering, and industrial use, the surface chemistry of SZrO is poorly understood. Ostensibly spurred by SZrO's impressive catalytic activity, the application-driven study of SZrO has resulted in deleterious ambiguity in requisite synthetic conditions for superacidity and insufficient characterization of acidity, porosity, and active site structure. This ambiguity has produced significant knowledge gaps surrounding the synthesis, structure, and mechanisms of hydrocarbon activation for optimized SZrO, stunting the potential of this catalyst in olefin cracking and other industrially relevant reactions, such as isomerization, esterification, and alkylation. Toward mitigating these long extant issues, we herein identify and highlight these current shortcomings and knowledge gaps, propose explicit guidelines for characterization of and reporting on characterization of solid acidity, and discuss the potential of pore-confined superacids in the efficient and selective depolymerization of polyolefins.

Rapid, efficient, and accurate determination of aflatoxins and capsaicinoids in vegetable oils by immunomagnetic sorbents coupled with UHPLC–MS/MS

AbstractA fast, simple, and sensitive analytic method was proposed for the simultaneous quantification of aflatoxins (AFTs) and capsaicinoids in vegetable oils by immunomagnetic sorbent coupled with ultra‐performance liquid chromatography coupled with tandem mass spectrometry. The immunomagnetic solid phase extraction (IMSPE) sorbents were synthesized with the monoclonal antibodies via cyanogen bromide magnetic sorbents, which could modify the surface magnetic sorbents under mild synthetic condition. The IMSPE procedure had the following aspects such as ease manipulation, easy disperse, quick isolation, eco‐friendly, and cost‐effective. The major conditions of IMSPE procedure were systemically studied, and the optimized pretreatment was accomplished in 15 min avoding complicated condition or sophisticated equipment. Excellent linearities were achieved by the correlation (R2) more than 0.9983. The limits of quantifications of all analytes ranged from 0.03 to 0.20 µg kg−1, and the recoveries were satisfactory ranging from 75.7% to 124.0% with the intra‐day and inter‐day precisions less than 10.1%. Additionally, the proposed method was used to analyze AFTs and capsaicinoids in retail oil samples. Overall, 25% of soybean and peanut oils and 12.5% of corn and blended oil were detected with AFTs, and no capsaicinoid was found. The content of AFTs was under the MRLs set by EU and China regulation for food quality and safety. The validated results indicated that this method could be utilized for a rapid, efficient, and accurate quantification of AFTs and capsaicinoids in complex lipid‐based matrix.

Perovskite versus Nonperovskite: Modulating the Nature and Optical Properties of One-Dimensional Chiral Lead-Bromide Networks.

In the last 5 years, low-dimensional chiral metal-halide semiconductors have attracted great interest in the generation of chiroptical activity. Among this new family of materials, one-dimensional (1D) networks have appeared as the best candidates for strong circular dichroism (CD) and circularly polarized luminescence (CPL). Here, we present a new family of 1D chiral lead-bromide materials prepared from organic S/R/rac-1-hydroxypropyl-2-ammonium (S/R/rac-HP2A) cations. The presence or absence of polarity in the crystal structure as well as the perovskite or nonperovskite nature of the inorganic network depends on the initial stoichiometry of metal-halide salt and chiral amine during the crystallization. The perovskite-type networks exhibit strong CD and second harmonic generation (SHG) responses, while the nonperovskite compounds show the presence of polymorphism in the crystal phase and weak natural optical activity in the final material. These results underline the impact of synthetic conditions and thin film morphology on the structural and optical properties of metal-halide hybrid networks.

Large-scale synthesis of dense Fe3C via ultra-high pressure method

In this work, a highly-dense cementite (Fe3C) was synthesized via ultra-high pressure method (UHPM). Different raw batches were prepared under identical synthetic conditions (1000 °C and 4.0 GPa for 10 min). Large amounts of Fe3C were produced from the raw material consisting of ∼ 6 µm iron powder with ∼ 1.5 µm graphite, illustrating that the particle size and carbon source are critical for synthesizing Fe3C via UHPM. The crystal size of the synthesized Fe3C was estimated to be approximately 19 nm by peak broadening of the X-ray diffraction pattern. Additionally, the synthesis of Fe3C was confirmed by electron probe microanalysis analyzer (EPMA) and X-ray photoelectron spectroscopy (XPS). Scanning electron microscopy (SEM) images showed clearly shaped grain boundaries. The excellent mechanical properties of the prepared Fe3C were confirmed based on an ultrasonic pulse reflecting method. According to the magnetic-hysteresis loop of the Fe3C, it displayed soft ferromagnetic properties.

Engineering Matrix-Free Drug Protein Nanoparticles with Promising Penetration through Biobarriers for Treating Corneal Neovascularization.

Protein drugs have been widely used in treating various clinical diseases because of their high specificity, fewer side effects, and favorable therapeutic effect, but they greatly suffer from their weak permeability through tissue barriers, high sensitivity to microenvironments, degradation by proteases, and rapid clearance by the immune system. Herein, we disrupted the standard protocol where protein drugs must be delivered as the cargo via a delivery system and innovatively developed a free entrapping matrix strategy by simply mixing bevacizumab (Beva) with zinc ions to generate Beva-NPs (Beva-Zn2+), where Beva is coordinatively cross-linked by zinc ions with a loading efficiency as high as 99.2% ± 0.41%. This strategy was universal to generating various protein NPs, with different metal ions (Cu2+, Fe3+, Mg2+, Sr2+). The synthetic conditions of Beva-NPs were optimized, and the generated mechanism was investigated in detail. The entrapment, releasing profile, and the bioactivities of released Beva were thoroughly studied. By using in situ doping of the fourth-generation polyamindoamine dendrimer (G4), the Beva-G4-NPs exhibited extended ocular retention and penetration through biobarriers in the anterior segment through transcellular and paracellular pathways, effectively inhibiting corneal neovascularization (CNV) from 91.6 ± 2.03% to 13.5 ± 1.87% in a rat model of CNV. This study contributes to engineering of protein NPs by using a facile strategy for overcoming the weaknesses of protein drugs and protein NPs, such as weak tissue barrier permeability, low encapsulation efficiency, poor loading capacity, and susceptibility to inactivation.

Magnetic Multienzyme@Metal-Organic Material for Sustainable Biodegradation of Insoluble Biomass.

Biodegradation of insoluble biomass such as cellulose via carbohydrase enzymes is an effective approach to break down plant cell walls and extract valuable materials therein. Yet, the high cost and poor reusability of enzymes are practical concerns. We recently proved that immobilizing multiple digestive enzymes on metal-organic materials (MOMs) allows enzymes to be reused via gravimetric separation, improving the cost efficiency of cereal biomass degradation [ACS Appl. Mater. Interfaces 2021, 13, 36, 43085-43093]. However, this strategy cannot be adapted for enzymes whose substrates or products are insoluble (e.g., cellulose crystals). Recently, we described an alternative approach based on magnetic metal-organic frameworks (MOFs) using model enzymes/substrates [ACS Appl. Mater. Interfaces 2020, 12, 37, 41794-41801]. Here, we aim to prove the effectiveness of combining these two strategies in cellulose degradation. We immobilized multiple carbohydrase enzymes that cooperate in cellulose degradation via cocrystallization with Ca2+, a carboxylate ligand (BDC) in the absence and presence of magnetic nanoparticles (MNPs). We then compared the separation efficiency and enzyme reusability of the resultant multienzyme@Ca-BDC and multienzyme@MNP-Ca-BDC composites via gravimetric and magnetic separation, respectively, and found that, although both composites were effective in cellulose degradation in the first round, the multienzyme@MNP-Ca-BDC composites displayed significantly enhanced reusability. This work provides the first experimental demonstration of using magnetic solid supports to immobilize multiple carbohydrase enzymes simultaneously and degrade cellulose and promotes green/sustainable chemistry in three ways: (1) reusing the enzymes saves energy/sources to prepare them, (2) the synthetic conditions are "green" without generating unwanted wastes, and (3) using our composites to degrade cellulose is the first step of extracting valuable materials from sustainable biomasses such as plants whose growth does not rely on nonregeneratable resources.

Bromopyrene Symphony: Synthesis and Characterisation of Isomeric Derivatives at Non-K Region and Nodal Positions for Diverse Functionalisation Strategies.

Pyrene, a renowned aromatic hydrocarbon, continues to captivate researchers due to its versatile properties and potential applications across various scientific domains. Among its derivatives, bromopyrenes stand out for their significance in synthetic chemistry, materials science, and environmental studies. The strategic functionalisation of pyrene at non-K region and nodal positions is crucial for expanding its utility, allowing for diverse functionalisation strategies. Bromo-substituted precursors serve as vital intermediates in synthetic routes; however, the substitution pattern of bromoderivatives significantly impacts their subsequent functionalisation and properties, posing challenges in synthesis and purification. Understanding the distinct electronic structure of pyrene is pivotal, dictating the preferential electrophilic aromatic substitution reactions at specific positions. Despite the wealth of literature, contradictions and complexities persist in synthesising suitably substituted bromopyrenes due to the unpredictable nature of substitution reactions. Building upon historical precedents, this study provides a comprehensive overview of bromine introduction in pyrene derivatives, offering optimised synthesis conditions based on laboratory research. Specifically, the synthesis of mono-, di-, tri-, and tetrabromopyrene isomers at non-K positions (1-, 3-, 6-, 8-) and nodal positions (2-, 7-) is systematically explored. By elucidating efficient synthetic methodologies and reaction conditions, this research contributes to advancing the synthesis and functionalisation strategies of pyrene derivatives, unlocking new possibilities for their utilisation in various fields.

Free‐Standing Janus Nanosheets: Ultrafast Self‐Assembly and Versatile Biphase‐Application

AbstractThe development of stable Janus architectures suitable for biphasic applications holds significant importance. A novel approach is introduced for interfacial supramolecular self‐assembly, resulting in 2D Janus nanosheets (OA‐TA/Fe) exhibiting an amphiphilic nature. These nanosheets consist of hydrophilic coordination complexes of ferric ions (Fe3+) and tannic acid (TA) on one side of both surfaces and hydrophobic alkyl chains on the other side of both surfaces. The synthesis of these 2D Janus nanosheets involves a simple, ultrafast, and environmentally benign process, eliminating the need for time‐consuming multistep procedures and harsh synthetic conditions typically associated with Janus architecture formation. By exploiting the inherent singular anisotropic wettability inherent in OA‐TA/Fe‐2, the efficacy of these innovative Janus nanosheets in the efficient separation of various organic liquid‐in‐water and water‐in‐organic liquid emulsions is elucidated. Subsequent post‐modification of OA‐TA/Fe has facilitated the highly efficient remediation of contaminated oily wastewater, serving as a model biphasic catalysis reaction, wherein the Janus nanosheets function simultaneously as emulsifiers and catalysts within biphasic mixtures. The methodology establishes a rapid self‐assembly approach for the creation of amphiphilic free‐standing Janus nanosheets, offering compelling prospects for their application in diverse fields, as exemplified by, but not limited to, the case studies presented herein.

Volatile acetic acid selective adsorption by biomass-derived activated carbon with humidity-resistance: Tunable implanting and activation approach of activator

The selective adsorption and capture of polar organic acid gas by activated carbon (AC) absorbent could solve the challenge of irritant volatile organic compound discharge. However, volatile acid gas selective adsorption by traditional activated carbon with humidity resistance remains challenged. In this study, we developed an innovative one-step chemical synthesis method using discarded banana peels as a carbon source to create porous carbon materials. The selection of activators including sodamide and potassium hydroxide along with tunable implanting means of activator under different activated temperatures were modulated to optimize the fabrication of activated carbon. The results reveal that the low dosage of NaNH2 activator (NaNH2/carbon precursor = 1) implanted into carbon precursor through one-step ball-milling could contribute an excellent structural properties, and higher activated temperature makes the mesoporous behavior of activated carbon more obvious. Based on various optimization conditions, the optimal sample, BAC900, displays remarkable structural features (SBET = 2302 m2/g, Vtotal = 1.968 cm3 g−1, V>2nm = 1.474 cm3 g−1), achieving exceptional acetic acid adsorption efficiency (24.105 mmol g−1). Comparative analysis under various synthetic conditions revealed a close linear relationship between the structural characteristics (total pore volume) of adsorbent and acetic acid adsorption efficiency. We further explored the role of mesopores in facilitating acetic acid adsorption at relatively high pressures and their contribution to enhancing the hydrophobicity of the adsorbent. Additionally, we employed the Differential Isothermal Heat (DIH) technique to predict adsorption selectivity at varying relative humidity, revealing the higher adsorption heat (57 kJ mol−1) of acetic acid compared to water vapor (36 kJ mol−1). This comprehensive study emphasizes the outstanding adsorption selectivity of adsorbent for acetic acid, even in humid environments. Furthermore, the low adsorption heat of the BAC900 indicates good reversibility and reusability, paving the way for the practical application of biomass-derived functional biochar adsorbents in the environmental management of threatening acid VOCs pollutants.

Application of Eu(III) activated tungstates in solid state lighting

Tungstates play a major role in the, now for more than 60 years, ongoing scientific research of Eu(III) activated phosphors. Similarly, to other compounds featuring a closed shell transition metal anion like molybdates, vanadates, niobdates, tantalates, and tungstates are a family of materials that offer a wide range of potential host matrices for rare earth ions. Furthermore, tungstates provide several favourable characteristics like facile synthetic conditions via solid state synthesis, the possibility of high activator concentrations (low concentrations quenching), as well as intrinsic sensitization of lanthanides ions through a ligand-to-metal charge transfer (W6+/O2−). This review sets in by discussing the fundamentals of Eu(III) luminescence followed by a closer look at some general features of tungstates and their respective intrinsic luminescence. Various Eu(III) activated tungstates are explored in detail regarding their synthesis conditions and optical properties. Their compositional makeups and structures are correlated to the resulting optical properties. Potential strategies to improve the luminescent efficiency of new rare earth doped tungstates are derived from these correlations. In the closing section some general remarks regarding thermal quenching, concentration quenching, and charge transfer energies are discussed. Finally, comparisons to the related molybdates are drawn and the prospects of commercial application towards different fields of optical technologies are explored.

Investigation of the effect of off-stoichiometric composition on oxygen transport in layered perovskite materials for SOFC cathode

Layered perovskite materials are of significant interest for potential use as cathodes in solid oxide fuel cells. This study employs deep-learning-aided molecular dynamics simulations to investigate the impact of off-stoichiometric composition in praseodymium barium cobalt oxide and samarium barium cobalt oxide on O-ion transport properties. It is observed that increasing the deficiency of lanthanide-site atoms while suppressing the formation of O vacancies enhances O-ion mobility. This finding suggests adjusting synthetic conditions to achieve this state by controlling the design composition and heating atmosphere. The underlying mechanisms for the simulation results are explored, including the migration energy barrier of O ions, Co’s oxidation state change, and alterations in crystal structure, which indicate that structural changes and secondary phase formation are closely linked to O-ion mobility. Ba and Co infiltrate vacant lanthanide sites in the crystals under conditions of high lanthanide site deficiency and low O vacancy concentrations, promoting the formation of secondary phases composed of Ba, Co, and O, thereby creating favorable conditions for O-ion migration.

Insight biological prospects of silver@graphene oxide nanocomposite synthesized by Muntingia calabura leaf extract: Stunning ROS-related antibacterial mechanism under visible light

In this study, silver@graphene oxide (Ag@GO) nanocomposite was synthesized using Muntingia calabura leaf extract with temperature controlled at normal conditions. It was accounted that the optimal synthetic conditions were recorded at 0.9 mL AgNO3 (5 mg/mL) solution, GO:AgNO3 = 1:1 (v/v), and reaction time of 20 min, as a witness of the uniform distribution of AgNPs on the GO sheets with the average size of 17.79 ± 3.95 nm. Afterward, the bioactivities of the Ag@GO were determined via the assays of antioxidant, anti-inflammatory, antifungal, antibacterial, and cytotoxicity performances. Along with this, the antibacterial mechanism was also examined through the addition of various scavengers into the Ag@GO suspension at visible illumination. As a result, the Ag@GO exhibited outstanding biological inhibition in all experiments in comparison with individual precursors of the extract, AgNPs, and GO. Interestingly, regarding the bacteriostatic effects of the Ag@GO on Pseudomonas aeruginosa and Staphylococcus aureus, the Ag@GO performed the highest antibacterial efficiency, especially under the photo-excitation of visible-light irradiation. As well, the generation of various radicals, namely hydroxyl (•OH), hydroperoxyl (•OOH), and superoxide (• O2−), as well as the non-radical hydrogen peroxide (H2O2) evidently promotes the bactericidal inhibition of the Ag@GO. Furthermore, the stability of the Ag@GO after three months of storage under the suspension system and with the foregoing results declared the prospects in biomedicine of nanomaterials from the green synthesis approach.