SEM Mapping Research Articles

Unveiling high resistivity mechanism in (0.8-x)BaTiO3-0.2BiScO3-x(Bi0.5Li0.5)TiO3 ceramics with good dielectric temperature-stability

Focusing on the high resistivity together with low intrinsic conduction in BaTiO3–BiMeO3 materials, it can contribute to the development of reliable high-temperature capacitor materials. In this work, x(Bi0·5Li0.5)TiO3-(0.8-x)BaTiO3-0.2BiScO3 (where x ranges from 0 to 0.2) ceramics were fabricated by a solid reaction method. The temperature stability of dielectric permittivity and resistance are improved significantly by the introduce of (Bi0·5Li0.5)TiO3 (referred to as BL) compared to BaTiO3–BiMeO3. The composition discrepancy due to chemical inhomogeneity can be determined by SEM and EDS mapping although XRD exhibit a single perovskite phase. The characteristics of distinct conductivity behaviors in micro-regions was measured by kelvin probe force microscopy (KPFM). The non-stoichiometry gives rise to two kinds of defects for charge compensation: an ionic compensation and oxygen-vacancy compensation in different grains. The increase of the hopping activation energy of charged carries enhances the high-temperature resistance of the system. The sample of x = 0.15 shows very good temperature stability of dielectric permittivity in the temperature range from 200 °C to 400 °C, and that of x = 0.1 exhibits the highest resistivity of 3.6 MΩ cm at 570 °C. The proposed method gives an efficient strategy for improving the dielectric temperature stability and insulation by the special defect compensation in the perovskite oxides.

Detection of Microplastic Contamination in Commercial Insect Meals

Background: Escalating global plastic production, expected to reach 34,000 million tons by 2050, poses a significant threat to human and environmental well-being, particularly in aquatic ecosystems. Microplastics (MP) and nanoplastics (NP), which originate from the degradation of plastics, are of concern due to their potential bioaccumulation and uptake of pollutants. This study addresses identification methods and focuses on insect meal, a raw material for aquaculture feed. Methods: By using different techniques, the study was able to detect MP and NP in insect meal samples. Chemical digestion with KOH at 60 °C efficiently removed organic matter without affecting the synthetic polymer polyethylene (PE). Filtration, confocal Raman microscopy, SEM, and TEM were used for comprehensive analysis, and integrity tests on PE films were performed using Raman and FTIR spectroscopy. The results showed the presence of PE microplastic particles in the insect meal, which was confirmed by correlative Raman and SEM mapping on a positively charged surface. In addition, the increased resolution of the Raman microscope identified submicrometric PE NP (800 nm). Transmission electron microscopy (TEM) with energy-dispersive X-ray spectroscopy (EDX) confirmed plastic-like structures in the insect meal, highlighting the presence of PE plastics characterized by irregular shapes and some agglomeration. The higher carbon concentration in the EDX analysis supported the plastic nature, which was also confirmed by Raman spectroscopy. Conclusions: The study provides a robust method for the detection of MP and NP in insect meal and provides valuable insight into the possible presence of plastics in insect-based aquafeeds. The combination of different analytical methods increases the reliability of the results and sets the stage for future investigations that could focus on the quantification of NP and the assessment of their potential environmental impact.

Transparent high entropy garnet ceramics by SPS

High entropy or multi-principles component oxides as a new class of materials have been widely investigated for various applications due to their unique properties and multi-functionalities in recent years. In this study, a high entropy transparent ceramics ((Gd0.2Tb0.2Y0.2Lu0.2Yb0.2)3Al5O12) has been fabricated by spark plasma sintering (SPS) using co-precipitation synthesized powders. The powder preparation process was studied by TAG-DSC and FTIR. The phase structure, morphology, and element distribution of the obtained powder and ceramic samples are explored by XRD, SEM, and EDS mapping. It shows that the high entropy oxide (HEO) ceramic powder has a pure garnet phase, nanoparticle size, and homogenous elements distribution. The sintered ceramic exhibits the highest in-line transmittance in the visible and IR range of approximately 52 % at 700 nm and 74 % at 3.6 μm, respectively. In addition, characteristic optical properties of the final ceramics were demonstrated by photoluminescence spectroscopy. This work indicated that high-entropy garnet transparent ceramics with multi-wavelength emissions will provide more possibilities for multifunctional optical applications in the future.

Nickel-doped magnetic carbon aerogel derived from xanthan gum: a competent catalyst for the degradation of single and binary dye-based water pollutants.

Toxic organic dyes (colorants) are one of the main causes of water pollution that releases destructive effluents in the environment. To overcome this issue, a fundamental need to produce a novel, efficient catalyst for the degradation and mineralization of dye mixtures has arisen. The objective of this research is to develop an eminent Ni-doped magnetic carbon aerogel (Ni-MCA) catalyst using graft co-polymerization method having xanthan gum as backbone doped with Ni-magnetic nanoparticles (Ni-MNPs), that do not show agglomeration and easy to separate. The examination revealed that Ni-MCA provided exceptional magnetic characteristics (Ms = 52.75emu/g) and potent catalytic activity for the degradation of mono- as well as binary-dye solutions of Congo red (CR) and methyl green (MG) dyes. The formation was verified by various characterization techniques such as FTIR, VSM, XRD, XPS, SEM, TEM, and EDX mapping. Interestingly, Ni-MCA shows faster result on anionic dye CR up to 97% with degradation rate of 5.647 × 10-1min-1, and MG dye shows degradation of 95.7% with the degradation rate of 2.169 × 10-1min-1, while dye mixture is showing 90% degradation with rate of 2.159 × 10-1min-1.

The synthesis of new polyhydroquinoline derivatives using nano-[Fe3O4@SiO2/N-propyl-1-(thiophene-2-yl) ethanimine][CoCl2] as a novel supported magnetite catalyst

In this work, nano-[Fe3O4@SiO2/N-propyl-1-(thiophene-2-yl) ethanimine][CoCl2] was prepared as a new supported nano magnetite catalyst and fully characterized by various analyses such as Fourier transform infrared spectroscopy (FT-IR), energy-dispersive X-ray spectroscopy (EDX), thermal gravimetric analysis (TGA), vibrating sample magnetometry (VSM), field emission scanning electron microscopy (FE-SEM), SEM coupled EDX (SEM mapping), and transmission electron microscopy (TEM). The prepared supported nano magnetite catalyst was successfully tested on the synthesis of new polyhydroquinoline derivatives containing of benzyloxy moieties by the reaction of aldehyde with dimedone, ethylacetoacetate and ammonium acetate. The products were prepared in short reaction times (20–45 min) and high yields (74–98 %) and identified by melting point, FT-IR, 1H NMR, 13C NMR spectroscopy and also mass spectroscopy for new compounds.

Synthesis and Investigation of the Hydration Degree of CA2 Phase Modified with Boron and Fluorine Compounds.

This study investigated the effect of fluoride and boron compound additives on the synthesis and hydration process of calcium aluminate (CA2). The analysis showed that the temperature of the full synthesis of CA2 without mineralizing additives was 1500 °C. However, the addition of fluorine and boron compounds at 1% and 3% significantly reduced the synthesis temperature to a range of 1100-1300 °C. The addition of fluoride compounds did not result in the formation of fluoride compounds from CaO and Al2O3, except for the calcium borate phase (Ca3(BO3)2) under certain conditions. In addition, the cellular parameters of the synthesized calcium aluminate phases were not affected by the use of these additives. Hydration studies showed that fluoride additives accelerate the hydration process, potentially improving mechanical properties, while boron additives slow down the reaction with water. These results highlight the relevance of fluoride and boron additives to the synthesis process and hydration kinetics of calcium aluminate, suggesting the need for further research to optimize their application in practice. TG studies confirmed the presence of convergence with respect to X-ray determinations made. SEM, EDS and elemental concentration maps confirmed the presence of a higher Al/Ca ratio in the samples and also showed the presence of hexagonal and regular hydration products.

Enhanced electrochemical performance of the electrodeposited nickel sulfide on ZIF-67@RGO composite for supercapacitor applications

Zeolitic imidazolate frameworks (ZIF), as a form of metal-organic frameworks (MOFs), are promising materials used as electrodes for energy storage devices. Their high electrical conductivity results from numerous conjugated systems and the collaboration between the ligand and cobalt significantly enhances their redox capacity. The bulk electrical conductivity and specific capacitance of ZIF materials can be enhanced by the incorporation of rGO and metal sulfide, respectively. Herein, ZIF-67@RGO nanocomposite was fabricated and then modified with 20.0 wt% Ni nanoparticles followed by co-electrodeposition of sulfur as a novel electrocatalyst. The prepared composites were analyzed using various techniques, including FT-IR, XRD, XPS, SEM, and EDX mapping. The electrochemical performance of the prepared composite electrodes was measured using different techniques such as cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), and galvanostatic charge-discharge (GCD). The S-Ni/ZIF-67@RGO electrode displayed excellent electrochemical behaviour which is evident in the high value of the specific capacitance of 1142.3 F g−1 at a current density of 1 A g−1. On the other hand, an asymmetric supercapacitor (ASC) was assembled by employing the unique composite material in conjunction with conductive carbon black. The power and energy densities of the ASC device were 774 W kg−1 and 88.2 Wh kg−1, respectively. The capacitance of S-Ni/ZIF-67-RGO is retained at 90.8% even after 3000 cycles, suggesting remarkable cycle stability. This study expands the application scope of ZIF-67 and introduces a new method for fabricating novel electrode materials.

A highly selective and sensitive trimethoprim sensor based on surface molecularly imprinted nanocavities coordinated polydopamine/gold nanorods-functionalized acupuncture needle microelectrode

Excessive amount of antibiotics have serious detrimental effects on the environment, making precise monitoring and removal increasingly crucial. Trimethoprim (TMP) is a typical kind of antibiotic. Herein, a novel microdetector was fabricated on the matrix of acupuncture needle (AN). The functional interface was constructed using a green electrosynthesis method, incorporating three-dimensional coral-like gold nanorods (3D-CAuNRs), polydopamine (pDA), polypyrole (pPY) and TMP molecules. Characterization was performed using electrochemistry, high-resolution SEM and elemental mapping techniques. Notably, nanocavities were formed through electropolymeric molecular imprinting, resulting in highly selective and sensitive detecting of TMP. This was attributed to the structure-complementary and configuration-suitable microenvironment, facilitating specific electron-transfer. The intrinsic properties of the microsensor were thoroughly investigated. Under optimized conditions, the sensor exhibited a wide linear range of 0.05 ∼ 50 µmol/L with a low limit detection of 0.017 µmol/L (S/N = 3) for TMP, along with high selectivity, reproducibility, and stability. Furthermore, the sensor demonstrated applicability for detecting TMP in environmental water, soil and cefalexin and trimethoprim capsules.

Synthesis of N,N′-alkylidene bisamides and Suzuki–Miyaura coupling reaction derivatives with Pd organometallic catalyst anchored to channels of mesoporous silica MCM-41

At first, an organometallic catalyst namely, Pd-DPyE@MCM-41@MNP was prepared through magnetic (Fe3O4) nanoparticles-doped into channels of mesoporous silica MCM-41 and then, anchoring a novel complex composed of di(4-pyridyl)ethylene and palladium on the inner surface of the support. This immobilized catalyst was successfully identified via VSM, ICP-OES, TEM, FTIR, TGA, SEM, BET, XRD, EDX and elemental mapping analyses. After that, it was used as a versatile, heterogeneous, and magnetically reproducible catalyst in the generation of N,N′-alkylidene bisamides (1a-13a, 8–20 min, 90–98%, 50 °C, solvent-free) and Suzuki–Miyaura coupling (SMC) reaction derivatives (1b-26b, 10–140 min, 86–98%, 60 °C, PEG-400). The VSM plot of Pd-DPyE@MCM-41@MNP displays that this nanocatalyst can be easily recycled by applying an external magnetic field. In both synthetic paths, this nanocatalyst was reused at least seven times without palladium leaching and significantly reducing its catalytic performance. Also, stability and heterogeneous nature of catalyst were approved via ICP-OES technique and hot filtration test.

Study on the wear characteristics of INCO939 alloy manufactured by laser powder bed fusion and casting.

This study examines the wear characteristics of INCO939 specimens spanning temperatures from 24 °C to 600 °C. Hardness measurements revealed higher values for laser powder bed fusion (LPBF) fabricated and heat-treated samples compared to cast ones. Friction tests indicated increasing coefficient of friction (COF) values for cast samples at high temperatures, while LPBF-fabricated and heat-treated samples exhibited gradual decreases. SEM and EDS mapping analyses highlighted oxidation as a protective mechanism against wear at elevated temperatures. Surface roughness worsened with temperature for cast samples but remained superior for LPBF-fabricated ones. Heat-treated specimens showed improved surface roughness at lower temperatures, decreasing from 30 µm at room temperature to smoother surfaces at 500 °C, but increased to 44 µm at 600 °C.

Strategically tailored double S-scheme heterojunction in h-MoO3 doped Bi7O9I3 decorated with Cr–CdS quantum dots for efficient photocatalytic degradation of phenolics

Phenolic compounds are widely used in various industrial processes, but they can be harmful to the environment if released without proper treatment. In this study, we developed a ternary nanocomposite (NCs) consisting of molybdenum trioxide, bismuth oxoiodide, and chromium-doped cadmium sulphide quantum dots h-MoO3/Bi9O7I3/Cr–CdS QDs (MBC) nanocomposite (NCs) to enhance the photocatalytic degradation of p-chlorophenol (p-CP). The nanomaterial morphology, distribution of depositing material, and heterojunction formation were investigated using SEM, TEM, SAED, and elemental mapping. Further, the structural characterization was done by XRD, XPS, and Raman spectroscopy which confirmed its purity, chemical states, bonding nature, and the presence of oxygen vacancies (OVs) and sulphur defects. The 30-MBC NCs exhibited the highest surface area of 354.5 m2/g and pore volume of 0.76 cm3/g, with the H3 hysteresis loop indicating their mesoporous nature. The Kubelka-Munk plot determined the band gap of the NCs to be 2.22 eV and ensured successful visible-light sensitization. PL and ESR studies revealed that 30-MBC NCs had the lowest charge carrier recombination and highest ROS production. The photocatalytic degradation of p-CP by 30-MBC NCs achieved 94% in 300 min. The highest efficiency was observed at 75 mg/L NCs, 150 mg/L p-CP, and pH 6. Additionally, NCs retained activity in the presence of different ions and degraded 82% p-CP even after six consecutive cycles. •O2− was the dominant ROS involved in the degradation process, while OVs and sulphur defects played a crucial role in ameliorating charge transfer in the 30-MBC NCs. GC-MS/MS analysis identified the possible degradation pathways of p-CP, and ECOSAR showed that less toxic by/end products were produced. Overall, this study highlights the promising potential of 30-MBC NCs for extensive wastewater treatment.

Construction and characterization of Fe3O4@BAAH-CuCl nanomagnetic catalyst: catalysis research in synthesis of 2-aryl quinazolines from prepared benzylamines

We have constructed Fe3O4@BAAH-CuCl nanomagnetic catalyst in ChCl-Urea (choline chloride deep eutectic as solvent) as a highly efficient catalytic system for the preparation of 2-aryl quinazoline derivatives through one-pot, three-component reactions of 2-bromobenzaldehyde with primary amines and sodium azide under molecular oxygen. FT-IR, VSM, SEM, TEM, TGA, XRD, EDX, ICP-OES and elemental mapping analyses confirmed the fabrication of Fe3O4@BAAH-CuCl nanomaterial. In this project, we first prepared various derivatives of benzylamines from reduction of aryl nitriles, then used the benzylamine products as substrates in the three-component synthesis of 2-aryl quinazoline derivatives in the presence of Fe3O4@BAAH-CuCl/ChCl-Urea as an efficient catalytic system. Although the synthesized products (primary amines and 2-aryl quinazolines) were known, their physical state was confirmed with the reported samples in the literature and the structure of all the products confirmed by 1HNMR and 1CNMR.

Crack-alleviated gold-assisted silica-titania three-layered fiber optic pH sensor

Gold-assisted silica-anatase (Au/AS) nanocomposite was synthesized by a sol-gel route at a low temperature (90 °C). Owing to sensing assessment, the mixture of indicators (bromophenol blue, phenol red, and creosol red) is encapsulated in Au/AS nanocomposite and deposited in three layers on optical fiber. TGA analysis confirmed the D-Au/AS nanocomposite thermal stability at higher temperatures ≤500 °C. SEM and EDX mapping confirmed the self-assembly of icosahedron structures at the nanometer scale. AFM revealed a porous triangular texture of three layers with RMS around 6 nm. The sensitivity of the three layers was estimated at around 17.7 counts/pH. The three layers of coated fiber revealed reversibility, stability, and fast response at 0.56 s in pH 12. The dynamic pH range of three-layer coated fiber was optimized at pH 1–12 and suggested that it has fast responsive sensing potential for applied fields.

Study on the pathway of performance improvement and mechanism of Gd2O2S:Tb3+ green phosphor

To improve the luminescence performance of Gd2O2S:Tb3+, Gd2O2S:Tb3+, Tm3+, Gd2O2S:Tb3+, Dy3+, Tm3+ and Gd2O2S:Tb3+, Dy3+, Tm3+@SiO2 phosphors have been prepared by molten salt method. The samples are characterized using XRD, SEM, TEM, FT-IR, UV-Vis absorption spectroscopy, photoluminescence, cathodoluminescence and thermal stabilization tests. XRD tests and refinement results show that the crystal structure of the phosphor is still the hexagonal Gd2O2S crystalline phase and the lattice parameter decrease due to Dy3+/Tm3+ occupying the Gd3+ sites. SEM images and mapping of each element show that the particle grain and all expected elements distribute uniformly. TEM results illustrate that SiO2 coating is in an amorphous form on the surface of the powder grains. FT-IR tests indicate that SiO2 is present on the powder surface through Si-O-Gd bonding. The results of photoluminescence and cathodoluminescence show that the luminescence intensity increase 50% while adding Tm3+ into Gd2O2S:Tb3+, Gd2O2S:Tb3+, Dy3+ phosphors caused mainly by the energy transfer from Dy3+/Tm3+ to Tb3+. The core-shell structure of Gd2O2S:Tb3+, Dy3+, Tm3+@SiO2 has better photoluminescence and cathodoluminescence and the fluorescence lifetime remains unchanged while SiO2 coats phosphor. And it has good thermal stability. Its luminescence intensity at 425 K reaches 71.4% of that at room temperature, which is better than the corresponding value (46.4%) for the uncoated sample.

Preparation of ionic liquid modified graphene composites and their adsorption mechanism of arsenic (V) in aqueous solution.

Graphene (GR) is a new type of carbon-based material that combines many excellent properties. In order to give full play to the excellent properties of graphene and expand its application scope, this study used ionic liquid SbF6 to modify it and successfully prepared ionic liquid modified graphene composites (H/GR), and studied its adsorption mechanism of arsenic in aqueous solution. By investigating the effects of reaction temperature, reaction time, pH, adsorbent (H/GR) dosage, and humic acid concentration on the removal rate of arsenic in aqueous solution, the experimental results showed that when the reaction temperature was 30°C, reaction time was 1h, pH was 6, H/GR dosage was 0.1g·L-1, and humic acid (HA) concentration was 10mg·L-1, the best arsenic removal effect was achieved with a maximum. The removal rate was 99.4%. The equilibrium adsorption capacity was well modeled by the Langmuir, Freundlich, and Tenkin models at 30°C. The Langmuir adsorption isotherm was the most consistent, with a calculated maximum value of 137.95 mg·g-1, which is higher than most adsorbents in the field. In addition, it was determined that the graphene surface was indeed immobilized with the ionic liquid [Hmim]SbF6 by SEM mapping and EDS energy spectroscopy observation, and the adsorption isotherms and pore size distribution maps of graphene before and after the loading of the ionic liquid were analyzed by BET, which further confirmed a significant increase in the microporosity and porosity of the modified H/GR, and furthermore, it was demonstrated that the arsenic ions are chemically bonded with and indeed adsorbed on the surface of the H/GR by FT-IR and XPS characterization analyses. The results of all experimental data studies indicate that the main mechanism of As(V) removal from water by H/GR is due to electrostatic adsorption, ion exchange, and complexation between the modified graphene itself and the ionic liquid [Hmim]SbF6 itself.

Efficient toluene degradation using Bacillus subtilis biofilm-supported Mn–Ce/zeolite catalysts

This study investigated a new approach for synthesizing Bacillus subtilis biofilm-supported Mn–Ce/zeolite catalysts for the degradation of gaseous toluene. Four different metal oxide nano-catalysts (ZMn, ZMnCe-10%, ZMnCe-20%, and ZMnCe-30%) were synthesized with varying ratios of manganese (Mn) and cerium (Ce) on zeolite nanoparticles. TEM, SEM, XRD, BET, XPS, and EDX mapping were used to examine these four samples, as well as simple zeolite. Based on these analyses, the catalytic activity of the prepared samples ZMn, ZMnCe-10%, ZMnCe-20%, and ZMnCe-30% for the complete oxidation of toluene and toluene intermediate products were tested with Non-thermal plasma (NTP) technology in a dielectric barrier discharge (DBD) reactor. Among all, ZMnCe-20% showed the highest toluene degradation efficiency (89%) at low concentrations (200 ​ppm) and humidity (>50%). Later, highly efficient and hydrophobic nano-biocatalysts were prepared by combining B. subtilis biofilm wild-type (WT) and engineered B. subtilis biofilm EPS with ZMnCe-20% catalyst. EPS is the main component found in biofilm matrix and plays a key role in influencing properties such as biofilm stability, electron transfer, surface roughness and hydrophobicity. Compared to WT B. subtilis biofilm, EPS overexpressed B. subtilis biofilm showed stronger growth and development on ZMnCe-20% nanocatalyst. Moreover, the NTP system packed with ZMnCe-20%/biofilm (EPS+) nano-biocatalyst exhibited the highest toluene degradation activity (99%) with (83%) CO2 selectivity, (up to 50%) reduction in NOx concentration and complete ozone decomposition at (250 ​ppm) toluene concentrations and increased humidity (>90%). High-energy electrons generated in the NTP system break the C–H and C–C bond between the rings of the toluene molecule, forming several byproducts which are later reacted with active radical species such as O, OH, and O3 and further converted into final degradation products (CO2 and H2O). The results demonstrated successful biofilm development and growth on the ZMnCe-20% catalyst with advanced features such as superhydrophobicity, H2O resistance, improved surface roughness, and electron generation. In short, the study's approach combines bioengineering and material science to develop sustainable nano-biocatalysts for removing VOCs in industrial and environmental settings.

The preparation of CuM/SiO2 (M = Bi, Mg, Mn) catalysts applied in ethynylation of formaldehyde for 1,4-butynediol synthesis: the positive interface effect of CuO and Bi2O3.

The ethynylation of formaldehyde catalyzed by Cu-based catalysts is an important synthesis method for 1,4-butynediol relating to high-value-added chemicals. In this work, a series of CuM/SiO2 (M = Bi, Mg, Mn) catalysts were prepared by a deposition-precipitation method and applied in the ethynylation reaction. The effects of different promoters (Bi, Mg, Mn) on the catalytic activity were investigated. The relationship between the catalyst structure and performance is systematically studied using XRD, TEM, SEM mapping, N2 low-temperature adsorption/desorption, FT-IR, XPS, and TG-DTA characterization analyses. The results show that 30Cu2Bi/SiO2 exhibits the highest 1,4-butynediol yield (70%) and selectivity (97%) after the ethynylation reaction for 7 h. Furthermore, compared with the commercial catalyst, 30Cu2Bi/SiO2 shows similar cyclic stability, 47% yield, and 98% selectivity for 1,4-butynediol after 8 times for about 60 h. It is suggested that small CuO particles are uniformly dispersed in 30Cu2Bi/SiO2 with the biggest specific surface area (446.37 m2 g-1). Moreover, the Cu-Bi interface existing in 30Cu2Bi/SiO2 plays an important role in stabilizing cuprous, not excessively reduced to metallic Cu. Therefore, during the ethynylation reaction, 30Cu2Bi/SiO2 has the most active Cu2C2 and the least polyacetylene by-products. In addition, the richest oxygen vacancies arising in 30Cu2Bi/SiO2 also contribute to the ethynylation reaction of formaldehyde.

Upconversion luminescence and temperature sensing properties of Ho3+,Yb3+-codoped Bi2WO6.

Ho3+ and Yb3+-codoped Bi2WO6 upconversion luminescent materials at different concentrations were prepared via a high-temperature solid-phase method. The X-ray diffraction patterns showed that Ho3+ and Yb3+ doping basically did not affect the orthorhombic crystal system structure of the Bi2WO6 matrix material. Scanning electron microscopy images showed that 3%Ho3+,10%Yb3+:Bi2WO6 consisted of irregular bulk particles with sizes in the range of 0.5-2 μm and some powder agglomeration. SEM mapping and EDS measurements of the powder showed that the elements were relatively uniformly distributed. Under 980 nm excitation, the emission intensity of Ho3+ was the largest for the 3%Ho3+- and 10%Yb3+-doped sample. With an excitation power ranging from 45 mW to 283 mW for the 3%Ho3+,10%Yb3+:Bi2WO6 sample, the relationship between the luminescence intensity and pump power was determined; the results indicated that the Ho3+ (538 nm, 546 nm, 660 nm, 756 nm) emission peaks originated from two-photon absorption. In the temperature range of 298 K-573 K, under 980 nm laser excitation, the maximum absolute temperature sensitivity Sa was 0.029% K-1 (373 K), the maximum relative temperature sensitivity Sr was 0.034% K-1 (348 K) for the Ho3+ thermally coupled energy levels 5F4/5S2, and the minimum temperature resolution δT was 1.2857 K (298 K). Under the same conditions, the maximum Sa was 51.02% K-1 (573 K), the maximum Sr was 1.85% K-1 (523 K) for the Ho3+ nonthermally coupled energy levels 5F5/5F4, and the minimum δT is 0.2477 K (448 K). The colour coordinates showed that the luminescence of the 3%Ho3+,10%Yb3+:Bi2WO6 sample gradually shifted from the green region to the red region with increasing temperature.

Minimizing defect states through multidentate coordination and morphology regulation for enhancing the performance of inverted perovskite solar cells.

The diversity of the defects present in perovskite materials negatively impacts both the power conversion efficiency (PCE) and the long-term stability of perovskite solar cells (PSCs). The chemical passivation of these defects has been addressed through a multifunctional molecule, 4-((trifluoromethyl)thio)benzoic acid, that contains the carbonyl (CO) group, which exhibits a strong passivation effect by interacting with both the organic cation (FA+) and uncoordinated Pb2+ ionic defects while the sulfur (S) heteroatom passivates Pb2+ defects at the grain boundary and on the surfaces of the perovskite layer. Additionally, the CF3 group protects the perovskite film from ambient degradation as well as stabilizing the perovskite framework by forming hydrogen and coordination bonds with the FA+ cation and Pb2+ ions, respectively. The interaction between CO and Pb2+ forms a Lewis acid-base adduct that regulates grain growth during crystallization, enhancing the perovskite film's surface morphology as confirmed by SEM, AFM, and PL mapping. This reduces trap-assisted recombination of charged carriers, thereby enhancing their lifetime and transport, as observed from TRPL, KPFM, and c-AFM analyses. As a result of the combined effect of the additive molecule, the optimized device showed a marked improvement in efficiency rising from 16.54% in the pristine device to 20.87% with a reduction in hysteresis. Moreover, the optimized device shows enhancement of stability by retaining ∼86% normalized PCE after 40 days of storage under ambient conditions at 25 ± 3 °C and a relative humidity of ∼45-55%.

A new Schiff base 2-benzoylpyridine-based copper complex on boehmite nanoparticles as a recoverable nanocatalyst for the homoselective synthesis of 5-substituted tetrazoles.

In this study, boehmite nanoparticles (B-NPs) were prepared by a simple process and then their surface was modified by (3-aminopropyl)triethoxysilane (3-APTES). The modified B-NPs (3-APTES@B-NPs) were functionalized by 2-benzoylpyridine Schiff-base ligand toward the immobilization of the Schiff-base 2-benzoylpyridine ligand on the 3-APTES@B-NPs's surface (2BP-Schiff-base@B-NPs). Finally, copper ions were coordinated with the supported Schiff-base ligand on B-NPs toward the formation of the final catalyst (Cu-2BP-Schiff-base@B-NPs). The prepared Cu-2BP-Schiff-base@B-NPs were characterized using FT-IR spectroscopy, BET analysis, XRD, SEM, AAS, TGA, EDX and elemental mapping. Further, Cu-2BP-Schiff-base@B-NPs were applied as a homoselective and recyclable catalyst for the synthesis of a diverse range of 5-substituted tetrazoles in PEG-400 as a green solvent. The main benefits of this protocol are high homoselectivity attributes, short reaction times, high product yields and TOF values, and further addition to the catalyst ability to be recycled at least four times without significantly losing catalytic efficiency.