Decrease In Activation Energy Research Articles

Irreversible Lattice Expansion Effects in Nanoscale Indium Oxide for CO2 Hydrogenation Catalysis.

Thermal energy has been considered the exclusive driving force in thermochemical catalysis, yet associated lattice expansion effects have been overlooked. To shed new light on this issue, variable temperature in situ high-resolution (scanning) transmission electron microscopy (HR-(S)TEM) and electron energy-loss spectroscopy (EELS) were employed to provide detailed information on the structural changes of an archetype nanoscale indium oxide materials and how these effects are manifest in reverse water gas shift heterogeneous catalytic reactivity. It is found that with increasing temperature and vacuum conditions, an irreversible surface lattice expansion is traced to the formation and migration of oxygen vacancies. Together, these changes are believed to be responsible for the decreased activation energy and improved reaction rate observed for the reverse water gas shift reaction. Studies of this kind provide new insight into how thermal energy affects thermochemical heterogeneous catalysis.

Synthesis and cyclic voltammetric studies of azo dye compounds derived from 1,5-dihydroxynaphthalene and their application as corrosion inhibitors for carbon steel in hydrochloric acid solution

New bis-azo dyes derived from 1,5-dihydroxynaphthalene were synthesized and characterized by elemental analysis, Fourier-transform infrared (FTIR) and proton nuclear magnetic resonance spectroscopy (1H NMR). These compounds were examined using differential pulse polarography (DPP) and cyclic voltammetry (CV) in Britton-Robinson buffer solutions with pH values ranging from 2 to 12. When the two NN centers of the examined azo compounds were cleaved to form the amine group, the bis-azo group was reduced with the loss of eight electrons, resulting in an irreversible diffusion-controlled cathodic peak. The reduction mechanism was postulated in view of the data obtained was found to be H+, e, e, H+. The application of these azo compounds as corrosion inhibitors for carbon steel in hydrochloric acid solution was investigated and the inhibition efficiency was found to be increasing with both time and concentration, reaching 97 % after 24 hours in the presence of 10−3 M for the three azo compounds. The Langmuir adsorption isotherm indicates that the suppression of corrosion is caused by the inhibitor molecules donating electrons to the empty d-orbitals of the surface of the carbon steel (chemical adsorption), as the calculated Gibbs free energy (∆Gads) is found to be around −40 kJ/mol. The influence of temperature on the parameters of corrosion was examined, and the thermodynamic parameters of corrosion were computed and examined. The results showed that increasing temperature causes increasing of the inhibition efficiency of the tested bis-azo dyes. The order of inhibition efficiency followed their donating affinity which increases in the order p-OCH3 > p-CH3 > m-CH3. Also, the results showed that these compounds causes decrease in entropy, enthalpy and activation energy due to their chemical interaction with the metal surface.

Influence of Ultrasound on the Rheological Properties, Color, Carotenoid Content, and Other Physical Characteristics of Carrot Puree

This study aimed to investigate the effect of ultrasonic frequencies (21 and 35 kHz) on the physical properties of carrot puree at different concentrations (9, 12, and 21 °Brix). The viscosity, total soluble content, density, color, and β-carotene content were tested. It was found that the viscosity of the puree, determined with respect to shear rate, concentration, and the use of ultrasonic treatment, indicates that the purees should be defined as shear thinning fluids. Moreover, a decrease in activation energy was observed with the increase in extract and ultrasonic treatment, which may cause changes in the rate of reactions occurring in the tested material. A significant effect of this may be the observed change in the color of the puree after ultrasonic treatment; the increase in frequency from 21 to 35 kHz caused an increase in redness and yellowness and a decrease in lightness, independently of concentration. The most significant color difference was noted in the puree with a 21 °Brix concentration, where a ΔE value of 21 was recorded. In contrast, the ΔE values for the other purees post-treatment remained below 5. The content of carotenoids did not change after sonication, independently of the concentration of carrot puree.

Cellulase immobilization on nano-chitosan/chromium metal-organic framework hybrid matrix for efficient conversion of lignocellulosic biomass to glucose

In the current work, cellulase from Aspergillus niger was successfully immobilized on a novel epoxy-affixed chromium metal-organic framework/chitosan (Cr@-MIL-101/CS) support via covalent method using glutaraldehyde as a crosslinker. The bare and cellulase-bound support was characterized by using various microscopic and spectroscopic techniques. Immobilized cellulase exhibited a high immobilization yield of 0.7 ± 0.01 mg/cm2, retaining 87.5 ± 0.04% of its specific activity and displaying enhanced catalytic performance. The immobilized enzyme was maximally active at pH 5.0, temperature 65 °C and 0.9 × 10–2 mg/ml saturating substrate concentration and the half-lives of free and immobilized cellulases were approximately 9 and 19 days, respectively. The decrease in activation energy, enthalpy change, and Gibbs free energy change, coupled with an increase in entropy change upon immobilization, indicated that the enzyme’s efficiency, stability, and spontaneity in catalyzing the reaction were enhanced by immobilization. Additionally, the immobilized cellulase efficiently converted rice husk cellulose to glucose, with a quantification limit of 0.05%, linear measurement ranging from 0.1 to 0.9%, and 8.5% conversion efficiency. The present method exhibited a strong correlation (R2 = 0.998) with the DNS method, validating its reliability. Notably, the epoxy/Cr@-MIL-101/CS-bound cellulase demonstrated impressive thermal and pH stabilities, retaining 50% of its activity at 75 °C and over 96% at pH levels of 4.5 and 5.0 after 12 h. Furthermore, it showed excellent reusability, preserving 80% of its activity after 15 cycles and maintaining 50% of its activity even after 20 days of storage. These results suggest that epoxy/Cr@-MIL-101/CS/cellulase composites could be very effective for large-scale cellulose hydrolysis applications.

A new AI-assisted data standard accelerates interoperability in biomedical research.

In this paper, we leveraged Large Language Models(LLMs) to accelerate data wrangling and automate labor-intensive aspects of data discovery and harmonization. This work promotes interoperability standards and enhances data discovery, facilitating AI-readiness in biomedical science with the generation of Common Data Elements (CDEs) as key to harmonizing multiple datasets. Thirty-one studies, various ontologies, and medical coding systems served as source material to create CDEs from which available metadata and context was sent as an API request to 4th-generation OpenAI GPT models to populate each metadata field. A human-in-the-loop (HITL) approach was used to assess quality and accuracy of the generated CDEs. To regulate CDE generation, we employed ElasticSearch and HITL to avoid duplicate CDEs and instead, added them as potential aliases for existing CDEs. The generated CDEs are foundational to assess the interoperability potential of datasets by determining how many data set column headers can be correctly mapped to CDEs as well as quantifying compliance with permissible values and data types. Subject matter experts reviewed generated CDEs and determined that 94.0% of generated metadata fields did not require manual revisions. Data tables from the Alzheimer's Disease Neuroimaging Initiative (ADNI) and the Global Parkinson's Genetic Program (GP2) were used as test cases for interoperability assessments. Column headers from all test cases were successfully mapped to generated CDEs at a rate of 32.4% via elastic search.The interoperability score, a metric for dataset compatibility to CDEs and other connected datasets, based on relevant criteria such as data field completeness and compliance with common harmonization standards averaged 53.8 out of 100 for test cases. With this project, we aim to automate the most tedious aspects of data harmonization, enhancing efficiency and scalability in biomedical research while decreasing activation energy for federated research.

The Electrical Conductivity Mechanisms and Dielectric Properties of Multiphase Co-synthesized CuV2O6–MnV2O6

AbstractMany research studies on photodegradation, energy storage applications, and biosensing have focused on single and mixed Cu and Mn divanadates (MV2O6, M2+ = Cu2+ and/or Mn2+). In this work, MV2O6 was synthesized, and its electrical conductivity and dielectric properties were studied. The electrical and dielectric properties were investigated in a frequency range of 0.1-300 kHz and a temperature range of 298 K to 573 K. The results indicate that the DC conductivity, AC conductivity, dielectric constant, dielectric loss factor, and loss tangent of the investigated materials increase with temperature, which support the contribution of grains and grain boundaries to the electrical properties. The materials exhibit non-Debye type relaxation, as indicated by the progression of the relaxation frequency. As frequency increases, the activation energy of AC conduction decreases, indicating that hopping conduction is the dominant mechanism. In all samples, the DC conduction activation energy is higher than the AC conduction activation energy. The circuit model was used to estimate the relaxation times. The results revealed remarkable dielectric characteristics, notably higher dielectric loss tangent values at frequencies below 1 kHz. Consequently, these materials can be used as electromagnetic attenuation absorbers. Graphical Abstract

Pyrolysis kinetics and thermodynamic analysis of bamboo, bagasse, and rice husk bio-chars: Implications for sustainable energy

This study focuses on the kinetic and thermodynamic analysis of bio-chars derived from popular and abundantly available biomasses like bamboo, bagasse, and rice husk. These bio-chars obtained by pyrolysis aim to be utilised without any refinement for combustion purposes minimising greenhouse gases and contributing towards sustainable development goals. However, understanding the kinetic and thermodynamic properties of bio-char is essential for optimizing its combustion performance. The results indicate a marked improvement in fixed carbon content and calorific value compared to the original biomass, alongside a reduction in average activation energy. For example, bamboo bio-char exhibited an increase in fixed carbon content from 16.02 % to 68.28 %, a rise in higher heating value from 16.84 to 25.48 MJ/kg, and a decrease in average activation energy from 183.63 to 121.22 kJ/mol in comparision to bamboo biomass. Additionally, the study introduces a novel approach that combines model-free and model-fitting techniques to simultaneously determine the reaction mechanism and pre-exponential factor such that the need for separate validation ends. This novel methodology offers a state-of-the-art framework for assessing the bioenergy potential of various biomasses, applicable for studies and comparisons on a global scale.

Enhanced functionalities of isovalently substituted 0.67(Bi1-xLaxFe0.97Ga0.03O3)-0.33(BaTiO3) relaxor piezoceramics synthesized via air quenching

The isovalently substituted lead-free binary solid solution, 0.67(Bi1-xLaxFe0.97Ga0.03O3)-0.33(BaTiO3) (BF-BT) (x ≤ 0.07), has been synthesized by solid state ceramic method via air quenching sintering. FTIR and XRD along with Rietveld structure refinement confirmed a pure perovskite phase with a pseudocubic structure (space group Pm3‾m) for developed compositions. SEM revealed a dense microstructure with fine grain size (<1.5 μm) and minimal porosity. XPS analysis reveals predominantly Bi+3 and Fe+3 states, along with oxygen vacancies (VO··). Ferroelectric studies demonstrated a maximum remanent polarization (Pr) of 12.3 μC/cm2 and coercive field EC of 30.95 kV/cm for La3+ concentration of x = 0.03. Overall decrement in Pr can be attributed to dipolar defect-induced random fields reducing the activation barrier for domain nucleation. Leakage current measurement reveals improved resistivity (∼108 Ω cm) up to an applied field of 30 kV/cm. Dielectric measurements unveiled two frequency-dependent anomalies in temperature dependence above room temperature, indicative of diffuse phase transitions. The Vogel-Fulcher model depicted an increasing freezing temperature (from 465 K for x = 0.01–551 K for x = 0.07) and decreasing activation energy (from ∼0.61 eV to 0.07 eV) with increasing La3+ concentration. The estimated diffuseness parameter around ∼2 suggested relaxor behavior. Doping with La resulted in increased dielectric permittivity at 10 kHz (from 4100 to 24066), showcasing the efficacy of site engineering in augmenting the functional properties of BF-BT for high-temperature dielectric and transducer applications.

Sintering activation energy and low-temperature sinterable process of Boron-lanthanide glass/Li2Zn3Ti4O12 ceramic composite systems for LTCC technology

This work investigates the characteristics of wettability, activation energy for sintering, evolution of phase structure, and behavior during the low-temperature sintering process of B2O3-La2O3-MgO-TiO2 (BLMT) glass/Li2Zn3Ti4O12 ceramic composites for low temperature co-fried ceramics technology (LTCC). As the BLMT glass content increases from 0 to 10 wt%, the average sintering activation energy (Ea) of the composite decreases from 450 ± 8 to 356 ± 37 kJ/mol. There are two phases the primary Li2Zn3Ti4O12 phase and the secondary LaBO3 phase, the latter precipitates from the BLMT glass after sintering at 700 °C. This indicates that BLMT glass promotes the sintering of Li2Zn3Ti4O12 ceramic below 900 °C. In composites containing 20 wt% or more glass, sintering is governed by both liquid-phase sintering and reactive viscous sintering. As the BLMT glass content increases, the impact of viscous flow on the densification process becomes more pronounced. Simultaneously, when the glass content is greater than 20 wt%, the glass precipitates LaBO3, TiO2, and MgLaB5O10 phases between 700 and 750 °C. After 850 °C, the glass melts and reacts with Li2Zn3Ti4O12 phase to produce a new TiO2 phase. Accordingly, the activation energy (Ea) of sintering the composite material increases from 393 ± 17 to 667 ± 1 kJ/mol.

Dynamics of heat transfer in complex fluid systems: Comparative analysis of Jeffrey, Williamson and Maxwell fluids with chemical reactions and mixed convection

This study addresses the complex dynamics of heat transfer in magnetohydrodynamic (MHD) systems involving Jeffrey, Williamson, Maxwell, and Newtonian fluids, focusing on how chemical reactions, activation energy, porosity, and mixed convection impact fluid behavior. The problem is critical due to the significant influence these factors have on industrial processes and applications involving non-Newtonian fluids. The developed a mathematical model represented by partial differential equations (PDEs), which were solved using similarity transformations and the fourth order Runge-Kutta (R-K) method combined with shooting technique, with MATLAB software facilitating the solution process. The results reveal that variations in magnetic field strength, porosity, and buoyancy force significantly affect fluid velocities, while radiation, Brownian motion, and thermophoresis alter temperature profiles. Furthermore, chemical reaction rates, Schmidt number, relaxation constant, and activation energy influence fluid concentrations. Key findings include that increasing porosity and magnetic field strength generally decreases fluid velocity, while higher radiation and Prandtl numbers reduce temperature. Chemical reactions and activation energy decrease fluid concentrations, with non-Newtonian fluids showing more pronounced effects compared to Newtonian fluids. The novelty of this work lies in its comprehensive analysis of multiple interacting parameters and their combined effects on heat transfer in MHD systems, providing insights that extend beyond previous studies in the literature. This research offers valuable implications for optimizing fluid dynamics in various industrial applications, including food processing, ink formulation, and friction reduction.

Evolution of activation energy for boron dissolution in the borosilicate glass during the initial leaching stage

Borosilicate glass is widely used for immobilizing high-level radioactive waste. In this study, two types of borosilicate glasses, Na-borosilicate and Zr-Na-borosilicate, were subjected to leaching within a temperature range of 50–90 °C, at 10 °C intervals. The rate of boron consumption was measured by Inductively Coupled Plasma Optical Emission Spectrometer (ICP-OES) and Fourier-Transform infrared spectroscopy (FTIR) techniques, and the boron activation energy was determined through the Arrhenius equation. The boron activation energies for Na-borosilicate and Zr-Na-borosilicate glasses are approximately 46 kJ/mol and 42 kJ/mol, respectively. The activation energy, which FTIR calculated, was consistent with that obtained by ICP-OES during the initial leaching time and decreased as the leaching time increased. The decrease in activation energy of boron is because the [BO3] structure was replaced by molecular water. The FTIR method offers an alternative approach for calculating the boron activation energy and contributes to understanding the leaching mechanism in the initial leaching stage.

Evaluation of Oxide|Sulfide Heteroionic Interface Stability for Developing Solid-State Batteries with a Lithium-Metal Electrode: The Case of LLZO|Li6PS5Cl and LLZO|Li7P3S11.

Developing solid-state batteries (SSB) with a lithium metal electrode (LME) using only one type of solid electrolyte (SE) is a significant challenge since no SE fits all the requirements imposed by both electrodes. A possible solution is using multilayer SSBs with an LME where the drawbacks of each SE are overcome by using layers of different SEs. However, research on inorganic SE1|SE2 heteroionic interfaces is still quite preliminary, especially regarding oxide|sulfide heteroionic interfaces. This work reports the electrochemical investigation of the heteroionic interface between Li6.25Al0.25La3Zr2O12 (Al-LLZO) and two representative materials for sulfide-based SEs: argyrodite-based Li6PS5Cl (LPSCl) and glass-like Li7P3S11 (LPS711). Through in-depth temperature- and pressure-dependent impedance analyses of multilayer symmetric cells at equilibrium (i.e., no current load), the electrical properties of the heteroionic interfaces are assessed. The pressure-dependent kinetic of the Al-LLZO|LPSCl pair is interpreted with the concept of geometric constriction resistance and show that its resistance is lower than for the Al-LLZO|LPS711 pair. Furthermore, the effect of Al-LLZO surface treatment on the electrical properties of the Al-LLZO|LPSCl heteroionic interface is evaluated. Such investigation shows that the value of the interface activation energy decreases when the Al-LLZO surface is heat treated, revealing a significant influence of the carbonate/hydroxide passivation layer on the heteroionic interface. Additionally, by cycling the symmetric cell for 900 h at 1.0 mAh·cm-2, it is revealed that the Al-LLZO|LPSCl interface has a lower impedance increase than the Al-LLZO|LPS711 interface, especially if the Al-LLZO is heat treated. With this work, we highlight that the oxide|argyrodite combination can be a promising candidate for multilayer SSBs with an LME. However, we show that an optimized LLZO surface treatment and chemical analysis of the interface are recommended for future research.

Assembling Zn2+ on surface of kevlar NanoFibers as functionalized separator for dendrite-free Zn anode and high-performance Zn metal batteries

The proliferation of wearable electronic products has made the development of flexible energy storage devices increasingly important. Among various options, aqueous Zn metal batteries are promising due to their low cost, safety, non-toxicity, environmental friendliness, and abundant element storage. However, the growth of dendrites on the anode surface of Zn metal batteries is a significant challenge to efficient transport of Zn2+, which leads to reduced battery capacity or even failure. This limitation hinders practical applications for these batteries. This study develops a functionalized separator with high ion transport performance and excellent mechanical performances by electrostatic assembling deprotonated PPTA− molecular chains with Zn2+ using Kevlar as a raw material. The successful assembly of Zn2+ is confirmed through chemical composition and functional group analysis. The prepared separator significantly shows the increased the transfer number of Zn2+ and decreased activation energy of Zn2+ deposition. The separator is used in Zn||Zn symmetric batteries, achieving a reversible deposition/stripping process of more than 180 h at a current density of 1 mA cm−2 and a deposition capacity of 1 mAh·cm−2. When applied to Zn||MnO2 batteries, an initial discharging specific capacity of up to 220 mAh·g−1 is obtained at a high current density of 2 A g−1, and the battery could be cycled stably for more than 1, 200 cycles, with a smooth and flat Zn anode surface and no obvious dendrite growth. The separator has good potential for flexible energy storage applications due to its excellent mechanical strength, which enables it to maintain high electrochemical activity even after bending 500 times at 180°. Overall, the functionalized separator effectively inhibits dendrite growth, improves the electrochemical stability of Zn metal batteries, and demonstrates significant application potential for other flexible energy storage applications.

Influence of stabilized zirconium dioxide and high hydrostatic pressure on the kinetics of sintering nanopowders of metastable aluminum oxide

The paper presents an analysis of the effect of processing powders with high hydrostatic pressure (HHP) (300, 500, 700 MPa) and stabilized zirconium dioxide (ZrO2 + 3 mol.% Y2O3, (YSZ)) doping on the compaction of metastable nanopowders mixture with γ+θ-Al2O3 + n% YSZ (n = 0, 1, 5, 10, 15 wt%) composition during sintering. The behavior of nanopowders at the initial stage of sintering was studied by dilatometry at a constant heating rate of 5 °C/min, in temperature range from 20 °C to 1500 °C. It has been determined that sintering of compacts occurs in two stages: compaction of γ + θ-Al2O3 (Ⅰ-st stage metastable phases), compaction of the stable α-Al2O3 (ⅠⅠ-nd stage), accompanied by inhibition between them. An “effect of mutual protection against crystallization” of powder mixtures was determined using the X-ray diffraction method. This is characteristic of systems obtained by co-precipitation. A connection between the above mentioned inhibition and an increase in the YSZ additive was found. That, also, correlates to the effect of “mutual protection against crystallization” of Al2O3 – YSZ powder mixtures. A study of the mechanisms and activation energies of γ+θ-Al2O3 + n% YSZ systems’ (n = 0, 1, 5, 10, 15 wt%) sintering depending on the YSZ additive amount and the HHP value showed that a dopant and pressure increase leads to activation energy decrease of the initial sintering stage, and the prevailing sintering mechanism is volumetric diffusion in corundum grains. Also, the work shows that for γ+θ-Al2O3 + ≥5 wt% YSZ systems, the optimal compaction pressure is HHP ≥500 MPa, which corresponds to the transition of the sintering mechanism from grain-boundary diffusion to volumetric diffusion.

Anomalous Temperature Dependence of the Triplet-Triplet Energy Transfer in Cereibacter sphaeroides I(L177)H Mutant Reaction Centers.

In photosynthetic reaction centers, quenching of the primary donor triplet state by energy transfer to the carotenoid molecule provides efficient suppression of generation of singlet-excited oxygen, potent chemical oxidant. This process in the Cereibacter sphaeroides reaction centers is thermoactivated, and discontinues at temperatures below 40K. In these reaction centers, substitution of amino acid residue isoleucine at the 177position of the L-subunit with histidine results in the sharp decrease of activation energy, so that the carotenoid triplets are populated even at 10K. Activation energy of the T-T energy transfer was estimated as 7.5cm-1, which is more than 10-fold lower than activation energy in the wild type reaction centers. At certain temperatures, the energy transfer in the mutant is decelerated, which is related to the increase of effective distance of the triplet-triplet transfer. To the best of our knowledge, the described mutation presents the first reaction center modification leading to the significant decrease in activation energy of the T-T energy transfer to carotenoid molecule. TheI(L177)H mutant reaction centers present a considerable interest for further studies of the triplet state quenching mechanisms, and of other photophysical and photochemical processes in the reaction centers of bacterial photosynthesis.

The effect of ethane on the chain reaction characteristics of methane–air mixtures explosions

In order to study the effect of ethane on gas explosions, the macroscopic properties, thermodynamics and kinetics of gas explosions were investigated using Chemkin numerical simulation software with the GRI-Mech 3.0 mechanism. Ethane was added to methane-air mixtures at seven different concentrations, such as 0%, 0.1%, 0.3% and so on, at constant initial temperature (1200 K) and pressure(0.9atm), respectively. The results show that the maximum explosion pressure, explosive power and ·H content was all maximized when the volume fraction of ethane was 3%, which was the most effective volume addition to promote gas explosion. Ethane reduced the time to peak energy of key radical reactions from 0.049s to 0.003s and reduced the sensitivity factors for reactions such as R155 and R158. When the added ethane was 8%, R158 and R98 shifted from inhibiting methane consumption to promoting methane consumption. Calculated by Arrhenius and Lindemann formulae found that ethane can act as the third molecule in unimolecular reactions, increasing the reaction rate constant and decreasing the activation energy, so accelerating the reaction. Due to the low addition of ethane, there was still a large amount of N2 acting as the third molecule, so the decrease in activation energy was small.

Relationship between structural, electrical properties and positron annihilation parameters of V2O5–Cu2O–P2O5 glasses

The structural and electrical properties of vanadium-copper-phosphate glasses with compositions of xV2O5–(40—x)Cu2O–60P2O5 (where x = 10, 20, 30, and 40 mol%) have been thoroughly investigated. As the amount of V2O5 increases, the density falls, and the molar volume rises. This effect may be attributed to the polarizing power strength, which reflects the ratio of the cation's charge to its diameter. As the concentration of V2O5 increases, the DC conductivity shows an upward trend while the activation energy decreases. Additionally, the microstructure—more specifically, the dimensions of vacancy-type defects-studied utilizing using positron annihilation lifetime (PAL) spectroscopy. A correlation was established between the sample characteristics and the PAL results. By computing the distribution of the long lifetime inferred from the PAL, the magnitude of the vacancy-type flaws was verified. The findings offer insightful information about how the PAL and sample characteristics relate to one another.

Effect of acidity of solid acid catalysts during non-oxidative thermal decomposition of LDPE

AbstractThermal decomposition of low-density polyethylene (LDPE) was monitored by thermogravimetry under N2 atmosphere in the presence of solid acid catalysts such as alumina (α-Al2O3, γ-Al2O3), crystalline silica-alumina (SA, molar ratio of Si/Al = 0.19) and amorphous silica-alumina catalysts (ASA, molar ratio of Si/Al = 4.9). Crystal structure and surface area of solid acid catalysts were measured by XRD and BET, respectively. The strength and distribution of acid sites of solid acid catalysts were estimated by NH3-TPD. It was observed that total acidity strength is in the order of ASA (1.77 μmmol NH3/g) &gt; AS (1.42 μmol NH3/g) &gt; γ-Al2O3 (1.06 μmol NH3/g) &gt; α-Al2O3 (0.06 μmol NH3/g). Thermal degradation behavior of LDPE with and without solid acid catalyst was monitored by TGA, where heating rates (β) of 5, 10, and 20 °C/min were employed under an inert atmosphere, and their activation energies (Ea), onset temperatures (Tinitial), decomposition temperatures (Tdecomp) were calculated and compared. The activation energy (Ea) was evaluated using the Coats-Redfern method. Solid acid catalysts with stronger acidity and higher surface area showed a decrease in activation energy and onset temperature. Activation energy of LDPE over ASA catalyst is decreased to 97.3 kJ/mol from thermal decomposition of LDPE without catalyst of 117.2 kJ/mol under heating rate of 10 °C/min. The isothermal decomposition of LDPE was monitored at 300 °C for 3 h with a heating rate of 10 °C/min, where 13.1% and 24.2% wt. loss were observed over SA and ASA, respectively, while only 0.7% wt. loss was observed for LDPE without a solid acid catalyst. Graphical abstract Single step decomposition of LDPE Thermal degradation behavior of LDPE monitored by TGA, with different heating rates (β) of 5, 10, 20 °C/min.

Optimization of d-p band centers as efficient active sites for solar energy conversion into H2 by tuning surface atomic arrangement

The lowered reaction energy barrier and accelerated dynamic behavior for photocatalytic H2O overall splitting (HOS) involving oriented chemisorption, activation and conversion of *H and oxyhydrogen intermediates are crucial for solar energy conversion into H2 (STH). Herein, the localized heterojunction (Cd-S-Ni) composed of NiS and CdS via. tuning surface atomic arrangement with S atoms as the shared ligands has been constructed to synchronously elevate and optimize Ni 3d (Ni ε3d) and S 2p (S ε2p) band centers as efficient active sites for chemisorption of oxyhydrogen and *H intermediates with a declined Cd 4d band center (Cd ε4d) to suppress reverse reaction. A sustainable STH of 3.21 % under AM 1.5 G has been completed over Cd-S-Ni with a decreased activation energy for H2 evolution, verified by fs-TAS, in situ DRIFTS and dynamic DFT. These results devote to solving the reaction energy barrier and dynamical bottleneck for HOS by optimizing εd and εp.

Effective rare-earth doping on semiconductor behavior for BaTiO3-based automotive MLCCs

Highly accelerated lifetime test (HALT) for lifetime evaluation was performed on the state-of-art automotive MLCC prototypes by varying Dy/Mg (donor/acceptor) ratio added to BaTiO3. The results clearly showed that the mean time to failure (MTTF) more than 280 times as the Dy/Mg ratio increased from 1.0 to 10.0. Since oxygen vacancies typically form in-gap state/defect at the donor level, the activation energy value under thermal activation process as a function of voltage was calculated and compared by non-destructive testing (I–V curve) for an accurate evaluation of the extrinsic behavior. It was found that barrier height at the Ni/BT interface decreases as the voltage increases, resulting in a decrease in activation energy. As the Dy/Mg ratio increases, the density of defects/in-gap states formed at the donor level in the bandgap by oxygen vacancies decreases, which may lead to a decrease in the number of electrons excited by the external voltage. Furthermore, it was verified that the calculated Schottky barrier height of the 10.0 Dy/Mg ratio under voltage has higher value than that of the 2.6 Dy/Mg ratio. Based on the results of this study, we propose a new indicator for the design of automotive MLCCs with high lifetime reliability that can be used for comparative analysis of additive compositions through non-destructive test (I–V curve) with low evaluation time/cost.