High Activation Energy Research Articles

Impact of calcination temperature, organic additive percentages, and testing temperature on the rheological behaviour of dried sewage sludge

Abstract The main objective of the present work is to evaluate the influence of calcination pretreatment (600–1,000°C), organic additive incorporation (4% methocel, 4% amijel, and 8% starch), and testing temperature (20–60°C) on the rheological flow behaviour of dried sewage sludge and sewage sludge ashes. Besides, the dependency of sludge systems rheology on total solid content (4–15%) and methocel percentage (3–6%) was also evaluated. Furthermore, characterization techniques such as thermal gravimetric analysis-differential scanning calorimetry, X-ray fluorescence, X-ray diffraction, Brunauer–Emmett–Teller, and scanning electron microscopy were employed to investigate, respectively, the thermal decomposition, the chemical composition, the structural variations, the specific surface area, the surface morphology, and microstructure of sludges. The analysis of rheological characteristics according to best-fitting rheological models such as Herschel–Bulkley, Ostwald–de Waele, Cross, and Carreau models revealed that the yield stress (τ 0) and infinite apparent viscosity (η ∞) increase with an increase in TS or methocel percentage and decrease with increasing calcination or testing temperature. The strong impact of testing temperature concerning the reduction of the viscosity involves high activation energy (E a). This last criterion was used to compare the inter-particle strength of sludge systems.

Synthesis and Luminescence Characterization of Novel Red-Emitting Phosphors Based on Eu3+-Activated K2Sr(MoO4)2 Molybdates for w-LEDs.

In this work, trivalent europium (Eu3+) ion activated K2Sr(MoO4)2 red phosphors have been synthesized through high-temperature solid-state reaction method at 750 ℃. Detailed analysis was conducted on the phase purity, morphology, and luminescence properties of the synthesized phosphors. X-ray diffraction (XRD) confirmed the successful formation of K2Sr(MoO4)2:Eu3+ phosphors with pure phase with space group С2/c. The photoluminescence (PL) spectroscopy was used to record the excitation and emission spectrum of Eu3+ activated K2Sr(MoO4)2 phosphor. Under the excitation of 280nm, the resultant samples exhibited the characteristic emissions of Eu3+ ions corresponding to the 5D0→7FJ transitions. The optimal doping concentration of Eu3+ ions was determined to be 35mol%. Concentration quenching mechanism was identified as the interaction of near-neighbor ions. The chromaticity coordinates of K2Sr(MoO4)2:35mol%Eu3+ were (0.659, 0.340) with a corresponding high color purity of 99.8%. The prepared K2Sr(MoO4)2:35mol%Eu3+ phosphor had good thermal stability with temperature quenching temperature (T0.5 > 420K) and high activation energy (Ea = 0.267eV). The exhaustive findings from this study form the basis for advocating the application of these phosphors in light-emitting devices.

Speedy synthesis of magnetite/carbon dots for efficient chromium removal and reduction: a combined experimental and DFT approach

Abstract Magnetic carbon dots (Fe3O4/N–CQDs) was prepared by and eco-friendly and one-step microwave method using sugarcane bagasse (SB) as a starting material, and applied to remove ad reduce Cr(VI) in wastewater. The magnetization process was performed by a novel microwave method instead of the long time conventional co-precipitation method. The prepared Fe3O4/N–CQDs showed high saturated magnetization (Ms ~ 38.047 emu/g). When neat N–CQDs and Fe3O4/N–CQDs were applied to adsorb Cr(VI), the R% was slightly higher in the case of Fe3O4/N–CQDs (93.86%) compared to N–CQDs (91.73%). Moreover, the reduction rate of Cr(VI) by Fe3O4/N–CQDs was higher than the N–CQDs. The study confirmed the presence of magnetic iron oxide (Fe-O) in the N–CQDs at 655 cm−1 using FTIR spectroscopy. Interestingly, XRD analysis revealed peaks indicative of elemental iron (Fe(0)) alongside the iron oxide. Furthermore, TGA/DTG analysis showed a significantly higher weight residue (∑RW) for Fe3O4/N–CQDs compared to N–CQDs alone, suggesting enhanced thermal stability due to the Fe3O4 component. This stability is further supported by higher activation energy (∑A) and pre-exponential factor (∑s) obtained for Fe3O4/N–CQDs compared to N–CQDs. The prepared Fe3O4/N–CQDs showed higher fluorescence compared to the N–CQDs, which make them suitable as a chemosensor for the future work. In addition, DFT calculations confirmed the high stability of the Fe3O4/N–CQDs compared to N–CQDs. Graphical Abstract

Synthesis and photophysical characterization of push-pull azobenzene derivatives featuring different π-bridges for photoresponsive applications

This study presents the synthesis, development, and comprehensive evaluation of a series of novel azobenzene derivatives – DMAC, DMAF, and DMAT – engineered with push-pull configuration by varying π-bridge substituents (benzene, furan, and thiophene, respectively). The research employs a combination of computational and experimental methods, including density functional theory (DFT) and time-resolved UV–Vis absorption spectroscopy, to explore the impact of these π-bridge modifications on the electronic, photophysical, and isomerization properties of the derivatives. Interestingly, the findings suggest that the π-bridge structure significantly influences the charge transfer characteristics, with DMAC exhibiting the most effective charge transfer and the highest photoisomerization efficiency. Time-resolved UV–Vis absorption spectroscopy demonstrates that all derivatives exhibit rapid initial E-to-Z isomerization upon light irradiation, followed by a slower approach to the photostationary state (PSS). Thermal Z-to-E isomerization kinetics are consistent with the activation energy barriers predicted by potential energy surface (PES) scans, with DMAC showing the slowest reversion due to its highest activation energy. This study contributes valuable insights into the structural influences on the photochemical dynamics of azobenzene derivatives, with implications for their applications in photoresponsive technologies.

Understanding degradation mechanisms and hydrogenation kinetics of intrinsic γ-FeTiH2

Understanding the fundamental reasons behind the degradation of FeTi material is crucial for its engineering applications. Regretfully, efforts to explain the origins of this behavior through experimental research have been limited mainly because of the difficulty of identifying the precise location that gives rise to such a phenomenon. To explore if the material's enthalpy change could meet DOE standards, we performed biaxial strain calculations along the (a)- and (b)-axes. The findings were promising, as we achieved a ΔH in the range of −0.5 % and −1 %, with values of −39 and −42 kJ/mol·H2, and desorption temperatures of 285.36 K and 330.53 K. These results align well with DOE criteria for effective hydrogen storage materials. Additionally, we confirmed the stability of our material under strain conditions through AIMD simulations, which showed that the material maintained its structural integrity without any broken bonds or significant deformations. Employing first-principles calculations, we conducted an in-depth exploration of various potential hydrogen diffusion pathways within the FeTiH2 compound. Our findings reveal that the most favorable migration sites are from the (4e)-site to (4e)-site and (2c)-site to (4e)-site, with fast diffusion energies of 0.32 eV and 0.35 eV, respectively. The stable site for hydrogen is situated at the (2c)-site, characterized by a notably high activation energy of 1.91 eV. This significant energy barrier indicates that the (2c)-site is the most stable for hydrogen atoms, which helps to explain the material's degradation over hydrogenation/dehydrogenation cycles.

Green corrosion inhibitors for nickel in acidic media utilizing novel imine ligand and its Zn (II) metal chelate supported by DFT calculation

L and ZnL complex act as corrosion inhibitors were synthesized and their structural elucidation were characterized via various spectroscopic and physicochemical tools. Correlation of experimental data with DFT calculation affords that ZnL complex is octahedral. L and ZnL compounds were used as essential components and environmentally benign inhibitors to reduce the rate at which Nickel as metal and its alloys corroded. In the investigative research, 0.5 M H2SO4 was used as the corroding medium. Electrochemical impedance spectroscopy and the Tafel plot were used to analyse the electrochemical performances of L, its complex with Zn, and the inhibitory effect in the acid under test. Processes of Ni corroding in an acidic solution have been examined in relation to additive existence and deficiency. The obtained data demonstrate that while the inhibitory effect increases as the dose of the additives is increased, density of corrosion current Icorr. gradually decreases. It is noted that inhibition efficiency decreases with increasing temperature especially at high temperature (55 °C) in the case of presence of 1 × 10−3 M of L as an additive (η = 70.4 %). Although, in the case of utilizing ZnL complex as an additive, it in noted that inhibition efficiency η% is nearly the same and slightly changed with raising temperature. In the case of existence high dose of ZnL, η% slightly increases with temperature indicating chemisorption process of the additive on Ni surface in the acidic medium. When the additives are present in the solution, both the cathodic and anodic reaction processes are impacted. Furthermore, the presence of the ligand or its complex reduces the amount of NiO that forms on the electrode’s exterior sides. This finding implies that the adsorption mechanism of ZnL additive species follows Langmuir model and that kind of ligand and its complex adsorption on its outside are chemical in nature. These results have also been confirmed by electrochemical impedance spectroscopy. The ligand and its complex were included as additives, which significantly improved nickel’s corrosion resistance, according to the results. Studies on the effects of temperature have been done with different additive doses and Tafel plot method. High activation energy value of (−79.3 kJ. mol−1) was achieved when using 1 × 10−4 M of the L as well as (−82.8kJ. mol−1) in the presence of 1 × 10−3 M of ZnL in 0.5 M H2SO4. The standard enthalpy change ΔH0ads. for Ni in the acidic medium taking many dosages of L and ZnL were −31.16 and –32.72 kJ/mol, respectively. In light of this result, the adsorption process was chemisorption and the adsorption method was exothermic. Positive ΔS0ads values are correlated with an increase in solvent energy and a rise in the water desorption entropy. Employing scanning electron microscopy, the outward side morphology of the corroded samples was examined. Through a scanning electron microscope, the framework and texture of the films of oxide that are generated on Ni after potentiodynamic polarisation at different doses of ZnL additive are apparent.

Using Near‐Infrared Irradiation for Heating Mechanochemical Reactions in Organic‐Dye‐Doped Epoxy Milling Jars

Albeit mechanochemistry is a novel promising technology that give access to reactivity under solvent‐free conditions, heating such reactions is sometimes compulsory to obtain satisfactory results in terms of conversion, selectivity and/or yield. In this work, we developed a novel approach using a dye that absorbs NIR photons and release the energy as heat. Hence, de novo milling jars in epoxy resin doped with the dye were thus produced to obtain reactors that would produce heat upon irradiation at 850 nm. Temperature profiles were recorded, depending on the irradiance, dye charge in the resin, and milling frequency, showing an excellent control of the temperature. The usefulness of the heating jar was then demonstrated in mechanochemical reactions that are known to require heat to yield the desired product, namely Diels‐Alder reactions with high activation energies and the newly developed rearrangement of a sydnone into corresponding 1,3,4‐oxadiazolin‐2‐one.

Using Near-Infrared Irradiation for Heating Mechanochemical Reactions in Organic-Dye-Doped Epoxy Milling Jars.

Albeit mechanochemistry is a novel promising technology that give access to reactivity under solvent-free conditions, heating such reactions is sometimes compulsory to obtain satisfactory results in terms of conversion, selectivity and/or yield. In this work, we developed a novel approach using a dye that absorbs NIR photons and release the energy as heat. Hence, de novo milling jars in epoxy resin doped with the dye were thus produced to obtain reactors that would produce heat upon irradiation at 850 nm. Temperature profiles were recorded, depending on the irradiance, dye charge in the resin, and milling frequency, showing an excellent control of the temperature. The usefulness of the heating jar was then demonstrated in mechanochemical reactions that are known to require heat to yield the desired product, namely Diels-Alder reactions with high activation energies and the newly developed rearrangement of a sydnone into corresponding 1,3,4-oxadiazolin-2-one.

Optical imaging of the stochastic nucleation kinetics and intrinsic activation energy of single spin-crossover nanoparticles

Cooperative spin crossover (SCO) compounds are one of the most promising molecular bistable solids due to their intriguing thermal hysteresis phenomena around room temperature. It is well known that hysteresis is an essential kinetic effect, however, accurate assessment of the spin transition kinetics of SCO nanomaterials remains scarce. Herein, we developed a thermal-optical methodology to image the thermally induced spin transition kinetics of single SCO nanoparticles in a quantitative, repeatable, and high-throughput manner. Single-particle measurement revealed an intrinsic nucleation-dominated spin transition mechanism, where a highly stochastic nucleation process was clearly observed during the repeatable measurements. By quantifying the dependence of nucleation time on temperature, the activation energy barriers for nucleation were further extracted at a single particle level. Based on this foundation, the high throughput of the optical imaging not only contributed to uncovering the significant nanoparticle-to-nanoparticle heterogeneity, with implications for a negative correlation between apparent activation energy barriers for nucleation and size of the SCO nanoparticles, but also facilitated identifying a minority with high activation energy at least twice the average value. The extraordinary performance was then attributed to the fewer defects within their structures, as confirmed by further results from the in situ creation of defects by thermal ablation, thereby setting the lower limit for the intrinsic activation energy of ideal SCO crystals and promising their potential for future applications in high-performance molecular devices.

Thermogravimetric Assessment of Biomass: Unravelling Kinetic, Chemical Composition and Combustion Profiles

Thermogravimetric analysis (TGA) was performed on six samples of pine wood, poplar sawdust and olive residue, and the kinetic parameters were evaluated by using isoconversional models. The hemicellulose, cellulose and lignin contents were also estimated using the Fraser–Suzuki deconvolution method. In addition, a range of thermodynamic parameters and combustion indices was calculated. Significant correlations were found between the kinetic, thermodynamic and combustion parameters. The ignition index showed an inverse relationship with the activation energy, whereas the burnout index correlated with enthalpy values for most samples. Higher heating rates during TGA increased ignition and combustion efficiencies but decreased combustion stability. Differences in behaviour were detected between the olive residues, which had a much higher lignin content (51.2–56.9%), and the woody biomass samples (24.2–29.2%). Moreover, the sample with the highest ash content also exhibited some distinctive characteristics, including the lowest high heating value and ignition index, coupled with the highest activation energy, indicating a less favourable combustion behaviour than the other samples. The particle size of the samples was also found to be critical for both combustion efficiency and safety.

Diffusion and Spectroscopy of H2 in Myoglobin

The diffusional dynamics and vibrational spectroscopy of molecular hydrogen (H2) in myoglobin (Mb) is characterized. Hydrogen has been implicated in a number of physiologically relevant processes, including cellular aging or inflammation. Here, the internal diffusion through the protein matrix was characterized, and the vibrational spectroscopy was investigated using conventional empirical energy functions and improved models able to describe higher-order electrostatic moments of the ligand. Depending on the energy function used, H2 can occupy the same internal defects as already found for Xe or CO (Xe1 to Xe4 and B-state). Furthermore, four additional sites were found, some of which had been discovered in earlier simulation studies. Simulations using a model based on a Morse oscillator and distributed charges to correctly describe the molecular quadrupole moment of H2 indicate that the vibrational spectroscopy of the ligand depends on the docking site it occupies. This is consistent with the findings for CO in Mb from experiments and simulations. For H2, the maxima of the absorption spectra cover ∼20 cm−1 which are indicative of a pronounced Stark effect of the surrounding protein matrix on the vibrational spectroscopy of the ligand. Electronic structure calculations show that H2 forms a stable complex with the heme iron (stabilized by ∼−12 kcal/mol), but splitting of H2 is unlikely due to a high activation energy (∼50 kcal/mol).

Corrosion Inhibition and Adsorption Behaviour of Centrosema pubescens Leaf Extract for Copper in HCl Solution

Study’s Excerpt In this study, Centrosema pubescens leaf extract (CPE) has been confirmed as eco-friendly and efficient green inhibitor for copper corrosion in hydrochloric acid. Detailed thermodynamic analysis, revealed that CPE adsorption follows a Freundlich isotherm model. SEM-EDX and FTIR characterizations confirmed the formation of a protective layer confirming the potentials of the plant extracts in sustainable corrosion prevention. Full Abstract The anti-corrosion behaviour of Centrosema pubescens leaf extract (CPE) on copper in 1.5 M hydrochloric acid was investigated using weight loss method at different temperatures, followed with scanning electron microscopy (SEM) surface characterization connected with energy dispersive X-ray spectroscopy (EDX). The Fourier transform infrared spectrum of CPE was obtained. CPE inhibition effectiveness depends on the temperature and its concentration. CPE restrains the copper corrosion with 94.26 % inhibition efficiency at 1.0 g/L of CPE and at 303 K. For the CPE-inhibited system, a higher activation energy (Ea) value (range of 31.09 to 38.70 kJmol-1) compared to 20.34 kJmol-1 of the blank solution was obtained. The reaction process is spontaneous and endo thermic, as indicated by the ΔH, ΔS and ΔG values calculated. CPE adsorption behaviour fitted best into Freundlich isotherm.

Entropy generation outcomes in peristalsis of Carreau–Yasuda nanofluid flow with activation energy

AbstractThis paper focuses on the study of activation energy and entropy generation in the peristaltic flow of a Carreau–Yasuda nanofluid. Peristaltic transport, coupled with entropy generation and activation energy in a curved geometry, has significant applications in biomedical and industrial processes involving non‐Newtonian fluids. Blood flow in the arteries, the movement of chyme in the gastrointestinal tract, and peristaltic motion replicate the natural muscular contractions that drive fluid flow in the physiological systems. The integration of entropy generation allows for the evaluation of energy efficiency and the analysis of losses due to viscous dissipation. Activation energy plays a crucial role in processes such as drug delivery, where temperature‐sensitive reactions or biochemical changes affect fluid behavior. In industrial applications, like peristaltic pumps in chemical reactors or polymer processing, the consideration of entropy and activation energy aids in optimizing thermal management and reaction rates. The mathematical model is developed under these assumptions, and the governing equations are numerically solved using the NDSolve function in Mathematica. Graphical results show that higher activation energy and concentration reduce the reaction rate, while the Bejan number and entropy generation increase with a larger Brinkman number. Velocity and temperature increase under slip conditions, whereas concentration decreases, and a stronger radial magnetic field reduces both velocity and the size of the trapped bolus.

Controllable preparation of hexanitrostilbene (HNS) microspheres with multi-cavity structure to enhance safety and combustion performance

Controlling the structure to meet the demand for high-energy, low-sensitivity energetic materials in modern military and civilian applications is an effective method. In this study, hexanitrostilbene (HNS) microspheres with a multi-cavity structure were prepared using nitrocellulose (NC) and fluororubber (F2604) as binders via microjet droplet technology. The effects of flow rate, receiving liquid temperature, and suspension concentration on the morphology, particle size, and cavity of the HNS microspheres were investigated. Furthermore, the impact of the multi-cavity structure on the microspheres' specific surface area, dispersibility, thermal properties, safety performance, and combustion performance was studied. Results showed that the multi-cavity HNS microspheres retained the raw materials' crystal structure while exhibiting improved dispersibility, higher activation energy, and shorter ignition delay. Moreover, the multi-cavity structure outperformed the solid structure in terms of specific surface area, safety performance, and combustion performance. This study opens up a new direction for the preparation of multi-structured energetic microspheres.

Corrosion study of cola soft drink cans

The study of corrosion in aluminium packaging is fundamental to ensuring the quality and safety of the product. The varnish layer present on metal packaging aims to minimize any interaction between the food or drink and the metal, as well as minimizing the corrosion process. The acidic nature of soft drinks, as well as the ions present in solution, such as phosphates, benzoates or chlorides, play a strong role in the oxidative process of aluminum. This study evaluated the corrosion of the body of aluminum cola cans. The beverage was first characterized and the results obtained were: pH =2.5; 7.5 oBrix; chloride concentration of 0.17g/L, acidity 0.17 %m/m; density 1.04 g/mL and concentration of reducing sugars was 11.3 %m/m. The corrosion of aluminum in model solutions with different concentrations of citric acid and NaCl was studied via linear polarization for samples with and without varnish. The statistical analysis carried out, via factorial design 23 with a triplicate at the center point, showed that the corrosion rate (CR) of the sample with varnish was significantly influenced by temperatures above 45 oC in the range of chlorides studied. On the other hand, the CR of the sample without varnish was strongly influenced by the combination of high temperatures and high chloride concentrations. Removing the varnish resulted in a higher activation energy (AE = 67.48 kJ/mol) when removed with acetone and then polished with sandpaper compared to the sample with varnish (AE = 88.92 kJ/mol). From a kinetic point of view, this showed the protective effect of this layer and its effectiveness against corrosion. The ΔHo and ΔGo activation parameters of the process were positive, showing that corrosion is an endothermic process with increased disorder when the varnish is removed, respectively. It is therefore important to buy the product with the packaging in good condition to guarantee the integrity of the protective layer and its quality, since oxidation of the aluminum can lead to products that compromise the quality of the food or drink.

Stacking fault energy during DRV-DRX competition in high-nitrogen austenitic stainless steel used in orthopedic implants

High-nitrogen (high-N) austenitic stainless steels (ASS) are used in orthopedic implants due to their mechanical properties, human biocompatibility, and affordable cost. However, the high content of (Ni–Nb–N)-rich precipitates can cause allergic reactions and significant challenges in the manufacturing of prostheses. This study investigates the competition between work hardening (WH), dynamic recovery (DRV), and dynamic recrystallization (DRX) during the physical simulation of an ASTM F-1586 steel by thermomechanical processing, using the Kocks-Mecking and Avrami constitutive models. The parameters were obtained through continuous isothermal torsion tests at the temperature range of 900–1200 °C, strain rates between 0.01 and 10 s−1 and a total deformation of 4.0. Determined by compositional-analytical methods, the stacking fault energy (γsfe) was correlated with the stress level (σi) according to the Uesugi and Dai models. Results indicated a high activation energy for hot deformation (Qdef = 587 kJ/mol), affecting the shape of the curves. The γsfe value varied along the curves, delaying the onset of the DRX (σc = 0.928σp). Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) analyses revealed a direct competition between work-hardened and recrystallized grains in the early part of the curves, due to WH-DRV synergy. After the peak stress (σp), the progress of DRX was slow, with the Avrami exponent (n) between 1.1 and 1.9, completing only after large deformations (σss = 0.714σp). The moderate γsfe value (69 mJ/m2) and fine precipitates of the Z-phase (CrNbN) (<20 nm) influence the grain boundary mobility during the DRV-DRX competition, delineating the stress-strain curve shape.

Efficient Oxygen Evolution Reaction on Catalyst‐Free Acid‐Functionalized Plastic Chip Electrodes

Innovative electrode design is critical for improving the oxygen evolution reaction (OER) and meeting rising global energy demands. Despite the development of numerous carbon materials for water splitting, their potential is hampered by sluggish kinetics, primarily due to high activation energy compounded by various smaller factors, including additives or binders used in electrode modification. To address these limitations, a catalyst‐free plastic chip electrode (PCE) for OER is developed. PCE is functionalized by oxidizing it in acidic media at 1.8 V versus Ag/AgCl and eliminates the need for additives, offering a more accurate industrial representation. The oxidation process enhances the electrode's surface area and introduces electrochemically active oxygen‐containing functional groups. Characterization of the modified PCE is conducted using scanning electron microscope, X‐ray photoelectron spectroscopy, Fourier transform infrared spectroscopy, X‐ray diffraction, Raman, and thermogravimetric analysis, while electrolyte analysis utilizes UV–vis spectroscopy and NMR. The PCE oxidized for 6 h (PCE@6) demonstrates improved OER performance, with an onset overpotential of 260 mV, an overpotential of 1.06 V versus reversible hydrogen electrode at 10 mA cm−2, and a Tafel slope of 494 mV decade−1. The modified PCE reduces overpotential and minimizes bubble formation, enhancing efficiency and showcasing its potential as a cost‐effective solution for alkaline water electrolysis systems.

A durable cobalt catalyst supported on Ni foam coated with Al2O3 for hydrogen generation from NaBH4 hydrolysis

A durable cobalt catalyst supported on Ni foam coated with Al2O3 (Co/Al2O3–Ni foam) is developed and analyzed using various analytical methods. In addition, the catalyst is tested to investigate the effects of the Al2O3 coating cycle, Co reduction cycle, and reaction temperature on hydrogen generation from NaBH4 hydrolysis. The Al2O3 coating cycle considerably affects hydrogen generation and the catalyst area required for a hydrogen generation rate of 1 L/min. However, the Co reduction cycle and reaction temperature slightly affect hydrogen generation and the catalyst area required for a hydrogen generation rate of 1 L/min. The catalyst exhibits an apparent activation energy of 64.3 kJ/mol, which is relatively higher than those of the other catalysts. Furthermore, the catalyst exhibits durability comparable to that of other catalysts. Thus, the Co/Al2O3–Ni foam catalyst with high apparent activation energy and comparable catalytic durability is suitable for the NaBH4 hydrogen generation system.

Cutting-edge applications of oleic acid-modified CdSiO3: Ce3+ phosphors: Artificial intelligence enhanced latent fingerprint detection, anti-counterfeiting and optical thermometry

A series of (1–11 mol%) Ce³⁺ doped CdSiO₃ phosphors are synthesized via a solution combustion method, and the sample with the optimal doping concentration underwent surface modification with oleic acid (OA). X-ray diffraction (XRD) analysis confirmed the formation of high-purity, well-crystallized CdSiO3:Ce3+ phosphors. Upon 347 nm UV excitation, the phosphor exhibited intense blue emission at 400 nm, with an optimized Ce³⁺ concentration of 5 mol%, attributed to dipole-dipole interactions. The OA-modified phosphor demonstrated significantly enhanced properties, achieving a color purity (CP) of 97.2% and Internal quantum efficiency (IQE) of 82.5%. The phosphor also exhibited excellent thermal stability, retaining 93.0% of its emission intensity at 423 K and a thermal quenching temperature exceeding 483 K, with a high activation energy (Eₐ) of 0.384 eV. In practical applications, the OA modified phosphor showed exceptional performance in latent fingerprints (LFPs) detection and anti-counterfeiting (AC) across different substrates, offering high resolution, contrast, and minimal background interference. MATLAB based analysis yielded a matching score of 94.52%, surpassing conventional benchmarks, underscoring the phosphor's potential for advanced fingerprint identification. These results demonstrate that the CdSiO₃:5Ce³⁺ phosphor is a promising candidate for applications in white light-emitting diodes (w-LEDs), optical thermometry, forensic analysis and AC technologies.

Novel Lewis Acid-Base Interactions in Polymer-Derived Sodium-Doped Amorphous Si-B-N Ceramic: Towards Main-Group-Mediated Hydrogen Activation.

Interest is growing in transition metal-free compounds for small molecule activation and catalysis. We discuss the opportunities arising from synthesizing sodium-doped amorphous silicon-boron-nitride (Na-doped a-SiBN). Na+ cations and 3-fold coordinated BIII moieties were incorporated into an amorphous silicon nitride network via chemical modification of a polysilazane followed by pyrolysis in ammonia (NH3) at 1000 °C. Emphasis is placed on the mechanisms of hydrogen (H2) activation within Na-doped a-SiBN structure. This material design approach allows the homogeneous distribution of Na+ and BIII moieties surrounded by SiN4 units contributing to the transformation of the BIII moieties into 4-fold coordinated geometry upon encountering H2, potentially serving as frustrated Lewis acid (FLA) sites. Exposure to H2 induced formation of frustrated Lewis base (FLB) N-= sites with Na+ as a charge-compensating cation, resulting in the in situ formation of a frustrated Lewis pair (FLP) motif (≡BFLA⋅⋅⋅Hδ-⋅⋅⋅Hδ+⋅⋅⋅:N-(Na+)=). Reversible H2 adsorption-desorption behavior with high activation energy for H2 desorption (124 kJ mol-1) suggested the H2 chemisorption on Na-doped a-SiBN. These findings highlight a future landscape full of possibilities within our reach, where we anticipate main-group-mediated small molecule activation will have an important impact on the design of more efficient catalytic processes and the discovery of new catalytic transformations.