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Ultra-high temperature ceramics (UHTCs), most notably transition metal carbides and borides, exhibit melting temperatures exceeding 3000 °C, making them appropriate candidates to withstand the extreme temperatures (∼2000 °C) expected to occur at the leading edges of hypersonic vehicles. However, their propensity to react rapidly with oxygen limits their sustained application. The high entropy paradigm enables the exploration of novel UHTC compositions that may improve on the oxidation resistance of conventional refractory mono-carbides and -diborides. The oxidation kinetics of candidate high entropy group IV + V (HfZrTiTaNb)C and (HfZrTiTaNb)B2 materials were evaluated at 1500–1800 °C using Joule heating in one atmosphere 0.1%–1% oxygen/argon gas mixtures for times up to 15 min. Possible mechanisms based on the resulting complex time, temperature, and oxygen partial pressure dependencies are discussed. The carbides formed porous and intergranular oxides. Oxidation resistance was improved upon a continuous external scale formation. The diborides formed dense external scales and exhibited better oxidation resistance compared to the carbides. This improvement was attributed to the formation of liquid boria. Both compositions showed an unexpected reduction in material consumption at 1800 °C for all times tested, compared to results at lower temperatures. An in-depth analysis of the composition and morphology of the oxide scale and sub-surface regions for specimens tested at 1800 °C revealed that the formation of denser group IV-rich (Hf, Zr, Ti) oxides mitigated the formation of the otherwise detrimental liquid-forming group V (Ta, Nb) oxides, leading to the improved oxidation resistance. [ABSTRACT FROM AUTHOR]

Ultra-high temperature ceramics (UHTCs), most notably transition metal carbides and borides, exhibit melting temperatures exceeding 3000 °C, making them appropriate candidates to withstand the extreme temperatures (∼2000 °C) expected to occur at the leading edges of hypersonic vehicles. However, their propensity to react rapidly with oxygen limits their sustained application. The high entropy paradigm enables the exploration of novel UHTC compositions that may improve on the oxidation resistance of conventional refractory mono-carbides and -diborides. The oxidation kinetics of candidate high entropy group IV + V (HfZrTiTaNb)C and (HfZrTiTaNb)B2 materials were evaluated at 1500–1800 °C using Joule heating in one atmosphere 0.1%–1% oxygen/argon gas mixtures for times up to 15 min. Possible mechanisms based on the resulting complex time, temperature, and oxygen partial pressure dependencies are discussed. The carbides formed porous and intergranular oxides. Oxidation resistance was improved upon a continuous external scale formation. The diborides formed dense external scales and exhibited better oxidation resistance compared to the carbides. This improvement was attributed to the formation of liquid boria. Both compositions showed an unexpected reduction in material consumption at 1800 °C for all times tested, compared to results at lower temperatures. An in-depth analysis of the composition and morphology of the oxide scale and sub-surface regions for specimens tested at 1800 °C revealed that the formation of denser group IV-rich (Hf, Zr, Ti) oxides mitigated the formation of the otherwise detrimental liquid-forming group V (Ta, Nb) oxides, leading to the improved oxidation resistance. [ABSTRACT FROM AUTHOR]

[Display omitted] • A novel ZnCoAl-LDH/Ti-Fe 2 O 3 photoanode is designed and constructed. • The ZnCoAl-LDH/Ti–Fe 2 O 3 photoanode achieved a photocurrent density of 3.51 mA/cm2 at 1.23 V vs. RHE. • The separation and transport behavior of photogenerated charges was investigated. • The synergistic effects among the three metals were revealed. The efficiency of photoelectrochemical (PEC) water splitting is hindered by the slow kinetics of the oxygen evolution reaction (OER). This study developed a composite photoanode for water oxidation by incorporating ternary LDHs (ZnCoAl-LDH) onto Ti-Fe 2 O 3 as a cocatalyst. The ZnCoAl-LDH/Ti–Fe 2 O 3 photoanode achieved a photocurrent density of 3.51 mA/cm2 at 1.23 V vs. RHE, which is 9.8 times higher than that of bare Ti-Fe 2 O 3. Through a series of characterizations, the synergistic effects among the three metals were revealed. Furthermore, the addition of Zn can induce the formation of more high-valent Co, increasing the conductivity of CoAl-LDH and significantly reducing the surface charge transfer resistance. These advantages significantly enhance the injection efficiency of ZnCoAl-LDH/Ti-Fe 2 O 3 (82 %), thereby accelerating the OER kinetics of Ti-Fe 2 O 3. Our work introduces new approaches for selecting photoelectrochemical cocatalysts and designing high-performance photoanodes for water splitting. [ABSTRACT FROM AUTHOR]

Dialkyl carbonates (DACs) own an environmentally friendly synthesis route, making them potential candidates as alternative fuels. However, for DACs to be widely accepted as an alternative fuel, a comprehensive understanding of their combustion behavior is essential. Dipropyl carbonate (DPrC) represents a transition from short‐chain to mid‐chain carbonates, understanding its combustion behaviors holds significance in unraveling the combustion chemistry of carbonates. In this study, the oxidation of DPrC was investigated with the initial fuel mole fraction of 0.5% at three equivalence ratios of 0.5, 1.0, and 2.0 within a temperature range of 550–1100 K in a jet‐stirred reactor for the first time. Gas chromatography was utilized for the quantitative detection of reactants, intermediates, and products. A detailed DPrC mechanism was first developed, and good agreements between measurements and simulations were obtained. A notable negative temperature coefficient (NTC) behavior was first observed in the oxidation of DACs. Such NTC phenomenon occurred at fuel‐lean conditions in the temperature range of 620–660 K, while only a weak low‐temperature consumption was observed at the stoichiometric condition. Kinetic modeling studies showed that this unique low‐temperature chemistry of DPrC can be attributed to the differences in the RO2 isomerization reactions between DPrC and short‐chain DACs. The RO2 isomerization via a six‐member ring transition state could happen in DPrC oxidation but not in dimethyl carbonate and diethyl carbonate oxidation, due to the different fuel molecular structure. Therefore, the subsequent reaction pathways via QOOH → O2QOOH → HO2Q = O + OH → OQ = O + OH were promoted and two OH radicals were released in this process. Moreover, it is conceivable that mid or long‐chain DACs could also exhibit an NTC phenomenon due to the increased potential for RO2 isomerization via a six‐ or seven‐member ring transition state, thereby increasing the likelihood of RO2 isomerization occurrence. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Wuhan University of Science & Technology is the property of Wuhan University of Science & Technology and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The objective of the present study is the treatment of pistachio processing industry wastewaters (PPIW) using the supercritical water oxidation method. The experiments were conducted within a 400–600°C temperature range and a 30–150 s reaction time range, while maintaining a constant pressure of 25 MPa and using an O2/COD ratio of 1:1. To observe the effects of the initial PPIW and O2 concentrations on the treatment efficiency, experiments were also conducted with O2/COD ratios ranging from 0.5 to 3, while maintaining a constant reaction temperature and time of 500°C and 60 s, respectively. The influence of reaction temperature, reaction time and O2/COD ratio on the total organic carbon (TOC) and total nitrogen (TN) contents of the liquid PPIW effluents were investigated. Treatment efficiencies up to 99.75% regarding TOC conversion and 78.72% regarding TN conversion were obtained in very short reaction times. Additionally, the kinetics of oxidation of PPIW was studied, and reaction rate expressions based on TOC and TN were proposed. [ABSTRACT FROM AUTHOR]

Developing electrocatalysts with fast reaction kinetics for the urea oxidation reaction (UOR) in the field of sustainable hydrogen production through urea-assisted water splitting remains challenging. Here, Ni1−xO/ Ni(OH)2 supported on nickel foam (Ni1−xO/Ni(OH)2/NF) is prepared via a defect engineering strategy by combining Zn doping and acid etching. The doped Zn species are partially removed, facilitating the formation of NiOOH during acid etching. Residual Zn species modulate the electronic structure of nickel sites, which intrinsically accelerate the reaction kinetics of Ni1−xO/Ni(OH)2/NF. Ni1−xO/Ni(OH)2/NF exhibits excellent performance for the UOR with a low potential of 1.346 V versus the reversible hydrogen electrode to attain 100 mA cm−2, fast reaction kinetics (18.7 mV dec−1), and excellent stability in an alkaline electrolyte. The enhanced reaction kinetics of Ni1−xO/Ni(OH)2/NF are clearly elucidated by operando electrochemical impedance spectroscopy and in situ Raman spectroscopy. Our study offers an effective approach for designing promising Ni-based UOR catalysts for the practical application of urea-assisted water splitting. [ABSTRACT FROM AUTHOR]

Unveiling the key influencing factors towards electrode/electrolyte interface control is a long‐standing challenge for a better understanding of microscopic electrode kinetics, which is indispensable to building up guiding principles for designer electrocatalysts with desirable functionality. Herein, we exemplify the oxygen evolution reaction (OER) via water molecule oxidation with the iridium dioxide electrocatalyst and uncovered the significant mismatching effect of pH between local electrode surface and bulk electrolyte: the intrinsic OER activity under acidic or near‐neutral condition was deciphered to be identical by adjusting this pH mismatching. This result indicates that the local pH effect at the electrified solid–liquid interface plays the main role in the “fake” OER performance. This local pH effect on the OER electrode process is further verified by integrating a wide spectrum of analytical approaches. This study will accelerate the understanding of the local proton‐induced effect on electrode interface processes and the development of advanced electrochemical activity. [ABSTRACT FROM AUTHOR]

Nickel–Iron Layered Double Hydroxides (NiFe LDH)-based electrocatalysts have evinced tremendous interest towards oxygen evolution reaction (OER) to overcome sluggish water oxidation kinetics. This study reports (i) engineering coordination environment of NiFe LDH by varying Ni–Fe ratios (3:1 to 1:3) and (ii) heterostructuring by growing the optimal 1:1 NiFe LDH in situ on multiwalled carbon nanotubes (MWCNT)-modified Ni foam via urea-assisted hydrothermal method and decorating with carbon quantum dots (CQD). The hybrid 0D-CQD/3D-NFL/1D-MWCNT shows unique 3D urchin-morphology comprising 2D nanoribbons with an electrochemical surface area of 252.72 cm2/cm2 geometric area and exhibits best overpotential of 172 mV at 100 mAcm−2, Tafel slope (37.2 mVdec−1), and stability (1.44V vs. RHE for 100 h at 100 mAcm−2). Effectively transferring electrons O H − → t h r o u g h C Q D N i F e L D H → M W C N T → N i F o a m , the heterostructured CQD/NFL/CNT exhibits minimal change in overpotentials even at higher current densities (204 mV at 500 mAcm−2 and 212 mV at 750 mAcm−2), demonstrating its enhanced OER properties. [Display omitted] • In Situ hydrothermal growth – NiFe LDH@Ni Foam – varying Ni:Fe ratios (3:1 to 1:3). • 0D Carbon QDs-3D NiFe (1:1) LDH urchins-1D MWCNT heterostructures. • Exceptional 252.72 cm2 electrochemical surface area on 1 cm2 geometric area. • Low overpotentials: 172 and 212 mV at 100 and 750 mAcm−2, 37.2 mVdec−1 Tafel slope. • Excellent stability with 1.44V vs. RHE for 100 h at 100 mAcm−2. [ABSTRACT FROM AUTHOR]

Residual Cu in steel, stemming from electrified products, is not only difficult to remove but is well known for its potential to impact the surface quality, property profile, and production efficiency by causing cracks during thermomechanical processing of steels. Less well understood, however, are the precise mechanisms of hot shortness taking place in specific steel grades in view of their complex chemical concentrations affecting oxidation kinetics, phase formation, and elemental partitioning. Furthermore, evaluating the susceptibility of hot shortness is notoriously difficult due to the elevated temperatures and oxidizing atmospheres, and no widely accepted testing methodology has been established yet. This article aims to contribute to both fields through investigations on the effects of 1 wt% Cu addition to the medium carbon quench and tempering steel 42CrMo4. Two different hot tensile test variants are performed and resulting microstructures and oxide layers are analyzed. Electron backscatter diffraction and energy‐dispersive spectroscopy measurements reveal the formation of wuestite and magnetite, as well as a complex layer containing multiple oxide types. Metallic Cu is found embedded in this multiphase layer as well as within the matrix, decorating internally formed oxides. The complex interactions between oxide scale formation and the liquid metallic copper are outlined and discussed. [ABSTRACT FROM AUTHOR]

A Solar Corrosion Fenton reactor (SCFr) was developed by packing an iron-carbon steel filament inside the reactor to enable the in situ release of Fe2+. A Box–Behnken experimental design was used to optimize the effect of HRT (20, 30, and 40 min), the mass ratios of the packed filament inside the reactor with respect to volume (0.1, 0.2, 0.3 w/v), and the peroxide dosage added (500, 1000, and 1500 mg/L), the response variables were the percentage removal of COD, color, and turbidity. The optimum conditions for SCFr were an HRT of 24.5 min, a ratio of 0.16 (0.0032 m2/L), and a peroxide dose of 1006.9 mg/L. The removal was 91.8%, 98.4%, and 87.3% COD, color, and turbidity, respectively. Without solar radiation, the percentage removal was reduced by 16.3%, 47.9%, and 34.0% in terms of COD, color, and turbidity, respectively. The concentration of Fe2+ released was 25.4 mg/L of Fe2+. Prolonged HRT increases Fe2+ concentration and turbidity, which increase COD. The oxidation kinetics were fitted to a Behnajady–Modirshahla–Ghanbery (BMG) model, which indicated a high oxidation rate that is reflective of low treatment times. The w/v ratio was the most significant factor; the release of Fe2+ was stimulated by UV radiation and the chloride concentration of wastewater, which prevents the formation of an oxide layer, thus allowing its continuous release, taking advantage of solar radiation and the pH and chloride concentration of the raw sample. [ABSTRACT FROM AUTHOR]

This study aims to employ the deconvolution method to investigate the thermal oxidation kinetics of fullerene C60 under non-isothermal conditions where STA (TGA-DSC) with various heating rates was used. Results revealed that the oxidation rate curves consisting of two overlapped peaks are composed of three steps deconvoluted by the Frazer-Suzuki function. Afterward, the kinetic analyses were conducted for each step to determine kinetic parameters. The kinetic model F1 (first-order reaction; g(α) = −ln(1-α)) was identified for steps (I) and (II) with E ≈ 115 and 108 kJ mol−1 and lnA = 12.2, and 11.4 min−1, respectively, and the model R3 (contracting sphere model; g (α) = 1-(1-α)1/3) was determined as the rate-controlling mechanism of step (III), with E ≈ 122 kJ mol−1 and lnA = 13.8 min−1. Electron microscopes like FESEM and TEM were employed to confirm the models obtained for the oxidation process. The results obtained in the case of fullerene C60, with presented thermal oxidation kinetic analyses based on the deconvolution method, indicate that this method can be regarded as a very valuable technique for studying thermal stabilities and complex oxidation kinetics of solid nanomaterials. [ABSTRACT FROM AUTHOR]

Electrochemical formic acid oxidation reaction (FAOR) is a pivotal model for understanding organic fuel oxidation and advancing sustainable energy technologies. Here, we present mechanistic insights into a novel molecular‐like iridium catalyst (Ir−N4−C) for FAOR. Our studies reveal that isolated sites facilitate a preferential dehydrogenation pathway, circumventing catalyst poisoning and exhibiting high inherent activity. In situ spectroscopic analyses elucidate that weakly adsorbed intermediates mediate the FAOR and are dynamically regulated by potential‐dependent redox transitions. Theoretical and experimental investigations demonstrate a parallel mechanism involving two key intermediates with distinct pH and potential sensitivities. The rate‐determining step is identified as the adsorption of formate via coupled or sequential proton‐electron transfer, which aligns well with the observed kinetic properties, pH dependence, and hydrogen/deuterium isotope effects in experiments. These findings provide valuable insights into the reaction mechanism of FAOR, advancing our understanding at the molecular level and potentially guiding the design of efficient catalysts for fuel cells and electrolyzers. [ABSTRACT FROM AUTHOR]

Oxidation resistance is crucial to the potential applications of high‐entropy carbides (HECs) at elevated temperatures. Here, we realize the exploration of (Hf, Ta, Zr, Cr)C high‐entropy carbides (HEC‐TM, TM = Hf, Zr, Ta, and Cr) with good oxidation resistance by optimizing their compositions. To be specific, 21 kinds of HEC‐xTM (x = 0–25 mol%) samples are fabricated by a high‐throughput ultrafast high‐temperature sintering technique, followed by oxidation testing at 1673 K for 30 min. Among all the HEC samples, the as‐fabricated HEC‐0Zr samples are proved to possess the best oxidation resistance with an oxidation depth of only 53 µm. Further study on isothermal oxidation kinetics demonstrates that the as‐fabricated HEC‐0Zr samples follow a linear oxidation law. The good oxidation resistance of the as‐fabricated HEC‐0Zr samples is believed to result from the (Ta, Me)2O5 phase with a low melting point, which can promote the densification of the oxide layer. This research opens up a new way for efficiently discovering new HECs for extreme applications. [ABSTRACT FROM AUTHOR]

High‐activity TiB2 submicron powders were synthesized via microwave‐assisted carbothermal reduction, and their oxidation behavior at 550°C–1000°C for 0.5–1.5 h in air atmosphere was carried out by the isothermal oxidation test. The phase composition and microstructure evolution of the oxidation products were performed by X‐ray diffraction (XRD), X‐ray photoelectron spectroscopy (XPS), and scanning electron microscopy (SEM). It was established that TiB2 submicron powders had been significantly oxidized at 550°C, and the oxidation products were TiO2 and B2O3. Hexagonal plate‐like TiB2 grains had been completely disappeared, and fragmented into uniform nano‐scale spherical TiO2 particles after being oxidized at 1000°C for 1 h, accompanied by the violent evaporation of B2O3 products at temperatures above 1000°C. In addition, the corresponding oxidation kinetics was investigated by using a non‐isothermal thermogravimetric (TG)–differential scanning calorimetry (DSC) technique. The results showed that the Mample power law (n = 1) was the most probable mechanism function, and the oxidation activation energy E of TiB2 submicron powders was 640.58 kJ/mol. [ABSTRACT FROM AUTHOR]

Copyright of Canadian Metallurgical Quarterly is the property of Taylor & Francis Ltd and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Iron–nickel-based superalloy is an ideal substitute for the expensive Inconel 625 and Inconel 751 alloys. To elucidate the evolution of the microstructure and properties of Ni30 alloy under different thermal treatment conditions, a systematic study was conducted on the microstructural transformation of the alloy's strengthening γ′ phase following solution treatment and aging, as well prolonged exposure at 750 °C, and the oxidation behavior of the Ni30 alloy was examined. During prolonged thermal exposure, grain growth occurs mainly in the initial stage, and after 200 h, the prolonged exposure time leads to a significant coarsening of γ′ precipitates, whose area fraction increases by more than 10 times compared to their unaged state. After 100 h of aging, the alloy reaches a peak tensile strength of 1270 MPa and a yield strength of 820 MPa; after 2000 h, the alloy maintains a relatively high strength with a slight decrease in ductility. The oxidation kinetic curve of Ni30 alloy follows the quasi-parabolic oxidation law at 750 °C, and its oxidation rate is consistently lower than 0.1 g·m−2·h−1 throughout the whole oxidation process, which indicates that it has excellent oxidation resistance. The external oxide layer of Ni30 alloy shows a bilayered structure, and no obvious surface porosity or flaking of oxidation products were observed throughout the high-temperature oxidation test. This study not only contributes to the improvement of material properties, but also promotes innovation and development in the field of high-temperature engineering applications that will help to meet the increasingly stringent requirements of high-temperature working environments. [ABSTRACT FROM AUTHOR]

Aqueous zinc–sulfur (Zn─S) batteries represent a promising technology for grid‐scale energy storage because of the advantages of environmental friendliness, low cost, and high theoretical capacity. However, the practical applications of Zn─S batteries are hindered by the sluggish oxidation kinetics of zinc sulfide (ZnS) during the charge process. Herein, a strategy of nucleophilic regulation is proposed to modulate the oxidation kinetics of ZnS by adjusting the Zn─S bonding strength. By screening different nucleophilic groups, it is found that tetramethylene sulfone (TMS) can not only strongly interact with Zn atoms of ZnS through sulfone group to lower the oxidation energy barrier but also effectively suppress the side reactions by shielding ZnS from the active water molecules, thus facilitating the complete conversion from ZnS to sulfur. Benefiting from these advantages, the aqueous Zn─S batteries assembled with TMS as a multifunctional electrolyte additive demonstrate a superior specific capacity of 799 mAh g−1 at a current density of 2.0 A g−1 and 649 mAh g−1 at a current density of 4.0 A g−1 with an enhanced capacity retention after long cycles. This work demonstrates the promise of nucleophilic regulation for modulating the cathode conversion reaction in aqueous Zn─S batteries and beyond. [ABSTRACT FROM AUTHOR]

Dry reforming of methane carried out via the chemical looping concept and employing microwave heating is a sustainable syngas (a mixture comprising hydrogen and carbon monoxide) production technology. Understanding the intrinsic reaction kinetics of reduction and oxidation is essential for successful scale-up of this technology. By employing magnetite as a microwave absorber oxygen carrier, we investigated the reaction kinetics at bulk temperatures in the range of 650–800 °C for reduction and 500–650 °C for oxidation. Results indicated both reactions followed a phase-boundary controlled (contracting sphere) reaction mechanism. Upon developing the reaction kinetics based on solid temperature relevant to microwave-heated particles, we estimated the activation energy to be 85 kJ/mol for the reduction reaction and 22 kJ/mol for the oxidation reaction. By developing the reaction kinetic of the reduction under microwave heating and based on bulk temperature, we estimated 68 kJ/mol as the activation energy of the reduction reaction. Comparing these values with the activation energy of magnetite reduction by methane under conventional heating (around 90 kJ/mol) indicated that microwave irradiation apparently decreased the activation energy. Consequently, by developing the reaction kinetics based on an appropriate temperature, i.e., solid temperature, we demonstrated that microwave primarily had a thermal effect in our study, increasing the reaction rate constant, rather than a non-thermal effect, like altering the activation energy. [Display omitted] • Dry reforming of methane through microwave-heated chemical looping. • Reduction and oxidation reaction kinetics. • Magnetite as an oxygen carrier and microwave absorber. • Phase-boundary reaction mechanism for reduction and oxidation reactions. • Enhancing reaction kinetics by microwave heating. [ABSTRACT FROM AUTHOR]

In coal mining areas, the ambient atmospheric and aqueous oxidation of pyrite minerals (FeS2) associated with coal as well as the other accompanying strata is significant in understanding the extent of acid mine drainage (AMD), the cause of severe environmental pollution. Therefore, in this paper, the oxidation kinetics of the coal-associated pyrite (CAPy) present in a coal sample (TpHM1) has been studied via aqueous leaching depyritization experiments at variety of temperatures and time intervals without the incorporation of any oxidizer. The outcomes obtained are juxtaposed with the standard pyrite mineral (SPM) oxidation at the same experimental conditions. Also, the coal and SPM slurry residues and filtrates obtained after aqueous leaching at 25 °C and 90 °C for 0 h and 24 h, respectively, were extensively analyzed through high-resolution transmission electron microscopy (HR-TEM), Powder X-ray diffraction (P-XRD), and X-ray-photoelectron spectroscopy (XPS) for evaluation of the mineralogical composition and proportions of iron and sulfur components during progression of the oxidation reaction. Both the reactions obey pseudo first-order kinetics during pyrite (FeS2) oxidation but a significant difference in the experimentally found activation energies (Ea) and rate constants (k) values of oxidation kinetics of both CAPy and SPM may be attributed to the varied geochemical compositions of the coal associated pyrite (CAPy). The rate constant for CAPy is much greater than that of SPM implying a higher Ea around 10.838 kJ/mol for SPM as compared to 1.941 kJ/mol for CAPy. The CAPy in coal (TpHM1) is more susceptible to atmospheric oxidation than that of SPM, leading to the formation of acid mine drainage with lower pH. In this paper, the pH values on the basis of stoichiometric pyrite oxidation reaction were calculated and compared with the pH values obtained after aqueous leaching of CAPy to interpret the extent of acid formation and pyrite dissolution. Hence, with the assistance of the current study, further studies on the effects of mineral impurities, whereabouts of pyrite minerals in coal seams, the significance of compositional differences in the CAPy, the effect of metal oxides, and the role of alkalinity producing neutralizing agents of coal in the oxidative dissolution process of pyrite can be investigated. [ABSTRACT FROM AUTHOR]

The challenges encountered by Pt‐based electrocatalysts in alkaline hydrogen oxidation reaction include high Pt dosage and conflicting demands for modulating adsorption strengths among diverse intermediates. Here, an ultrasmall Pt cluster grafted on antimony tin oxide nanocrystalline with strong electron donor ability to minimal Pt dosage yet maximized electrocatalytic performance is developed. Mechanism studies show that the formation of Pt–Sn/Sb interaction at the heterointerface and the resultant reversed electron transfer selectively enhance the adsorption for OH‐ while concurrently weakening the binding strength for *H and CO toward Pt clusters. This accelerates the kinetics of H2/CO oxidation by promoting the binding of OH species with *H/*CO, yielding the catalyst with up to 5.7‐fold higher mass‐specific activity than benchmark Pt/C and increased resistance to CO poisoning. This work demonstrates the rational design of the synergistic multi‐site interactions towards advanced Pt‐based catalysts. [ABSTRACT FROM AUTHOR]

Constructing bifunctional sites through heterojunction engineering to accelerate water formation has become a pivotal strategy to improve the alkaline hydrogen oxidation reaction (HOR) kinetics, which is mainly focused on the synergistic effect of neighboring sites and the energetics of the surface reaction steps. However, the roles of the surface migration of key intermediates that go beyond the bifunctional mechanism limited to neighboring atoms have usually been ignored. Using the heterostructured Ni3C−Ni catalyst as a model, we found that the rapid surface migration of OHad species from the positively charged Ni3C to the negatively charged Ni component played a decisive role in facilitating water formation. Such unprecedented surface migration of OHad is induced by the large discrepancy between the local surface charge densities and interfacial environments of the Ni3C and Ni components under operating conditions. Benefiting from this, the resultant Ni3C−Ni exhibited outstanding mass activity for the alkaline HOR, which was approximately 19‐fold and 21‐fold higher than those of Ni and Ni3C, respectively. These findings not only provide novel insights into the alkaline HOR mechanism of heterostructured catalysts but also open new avenues for developing advanced electrocatalysts for alkaline fuel cells. [ABSTRACT FROM AUTHOR]

The poor carrier separation capability and sluggish water oxidation reaction kinetics are two critical factors that impact the photoelectrochemical (PEC) water splitting performance of the bismuth vanadate (BiVO4) photoanode. Previous studies have demonstrated that doping with rare‐earth elements to induce lattice distortions and loading oxygen evolution reaction (OER) co‐catalysts are effective strategies for enhancing carrier separation capabilities and accelerating the kinetics of the water oxidation reaction. Herein, Cu2+‐doped RuO2 (Cu‐RuO2) particles are anchored onto rare earth element Thulium (Tm)‐doped BiVO4 (Tm‐BiVO4) photoanode substrates, constructing an integrated Cu‐RuO2‐Tm‐BiVO4 photoanode. The newly integrated photoanode not only achieves a photocurrent density of 5.3 mA cm−2 at 1.23 V versus a reversible hydrogen electrode (vs RHE), but also exhibits exceptional stability. A series of detailed physical and chemical characterizations as well as density‐functional theory (DFT) calculations demonstrate that Tm doping induces lattice distortion in BiVO4, enhancing the internal electric field and thereby facilitating carrier separation. Moreover, the anchored Cu‐RuO2 particles not only lattice‐match with the Tm‐BiVO4 photoanode, reducing interfacial transfer resistance, but also expedite the kinetics of the water oxidation reaction. The profound significance of this work is that it offers a reference for the future design and fabrication of novel integrated photoanodes. [ABSTRACT FROM AUTHOR]

The effects of varied aging treatments are investigated on microstructure and properties in a ZL702A/SUS304 steel bimetal. Si and Al2Cu precipitates are detected in aluminum matrix after peak aging at 80 °C, 120 °C, and 160 °C, all of which yield close hardness within 77 ~ 79 HV. Notably, 80 °C peak aging produces finer, denser, and more uniform precipitates, stemming from the better thermodynamic and kinetic precipitation conditions. A thin oxidation layer is generated at AlFe(Si) transition layer/steel matrix interface after solid solution treatment. The layer remains in thinness (< 1 μm) under 80 °C peak aging but seriously thickens under 120 °C (avg. 16.2 μm) and 160 °C (avg. 12.9 μm), ascribed to the varied diffusion and oxidation kinetics. This generates higher average shear strength of 38.2 MPa in former than that of 28.5 MPa in latter. Fractography indicate fracture under shear loading propagates at thin oxidation layer and occasionally to steel side in 80 °C low temperature bimetal, relieving the devastating fracturing completely through thick fragile oxidation layer in 120 °C and 160 °C peak-aged ones. This work highlights low temperature aging strategy for fine precipitation hardening in aluminum and meantime maintaining a good interfacial bonding of aluminum/steel bimetal. [ABSTRACT FROM AUTHOR]

Lemon IntegroPectin sourced via hydrodynamic cavitation of lemon industrial processing waste in water only shows high antibacterial activity against Gram‐negative Escherichia coli. Insight on the antibacterial mechanism gained by investigating the oxidation kinetics of the phytocomplex at 0.5 mg/mL concentration in contact with the bacteria indicates that the oxidative stress, measured by reactive oxygen species (ROS) produced at the bacterial surface, is significantly higher than that generated by H2O2 0.5 M. Given the nontoxic and mitoprotective nature of this bioconjugate sustainably extracted from an abundant biological resource, these findings are promising toward a new antimicrobial treatment against polymicrobial infections unlikely to develop drug resistance. [ABSTRACT FROM AUTHOR]

The exposure to spontaneous combustion of coal subjected to high ground temperatures increases as the depth of mine excavation increases. To research the oxidative heat release characteristics of deep coal, a study was carried out to characterize the oxidation kinetics and thermal effects on coal in deep thermal environments; deep coals (heat-treated coals) in 30°C (T30), 45°C (T45) and 60°C (T60) environments were prepared using a simultaneous thermal analysis, and the thermal weight characteristics (TG) and thermal release characteristics (DSC) of heat-treated coals were tested by simulating coal samples in different deep thermal environments; the thermal effects of heat-treated coals were analyzed by oxidation kinetic theory. The findings indicated that the characteristic point temperature of the coal gradually reduces (T60 has the lowest oxidation characteristic temperature) as the heat treatment temperature increases, and the maximum mass loss (63.76%) during thermal treatment coal oxidation occurs in the combustion stage. The oxidation reaction mechanism function for the low-temperature oxidation phases of the deep coal conforms to the Z-L-T equation with a three-dimensional diffusion reaction mechanism. As the temperature of the thermal environment is increased, the apparent activation energy of the coal decreases and the exothermic heat increases. This increases the tendency for oxidation of the deep coal, making it more amenable to spontaneous combustion as the ambient temperature at depth rises. The results contribute to a theoretical framework for monitoring and preventing coal spontaneous combustion fires in deep mine excavations. [ABSTRACT FROM AUTHOR]

The redox state of the plastoquinone (PQ) pool in thylakoids plays an important role in the regulation of chloroplast metabolism. In the light, the PQ pool is mostly reduced, followed by oxidation after light cessation. It has been believed for a long time that dark oxidation depends on oxygen, although the precise mechanisms of the process are still unknown and debated. In this work, we analyzed PQ pool oxidation kinetics in isolated pea (Pisum sativum) thylakoids by tracking the changes in the area above the OJIP fluorescence curve (Afl) over time intervals from 0.1 s to 10 min in the dark following illumination. Afl served as an indirect measure of the redox state of the PQ pool that enabled quantification of the rate of PQ pool oxidation. The results showed a two-phase increase in Afl. The "fast" phase appeared to be linked to electron flow from the PQ pool to downstream acceptors of the photosynthetic electron transport chain. The "slow" phase involved oxidation of PQH2 through oxygen-dependent mechanisms. Adding octyl gallate, an inhibitor of plastid terminal oxidase (PTOX), to isolated thylakoid suspensions decreased the rate of the "slow" phase of PQ pool oxidation in the dark after illumination. The addition of either H2O2 or catalase, an enzyme that decomposes H2O2, revealed that H2O2 accelerates oxidation of the PQ pool. This indicates that under conditions that favor H2O2 accumulation, H2O2 can contribute substantially to PQ pool oxidation in the dark after illumination. The contribution of PTOX and H2O2 to the modulation of the PQ pool redox state in plants in the dark after illumination is discussed. [ABSTRACT FROM AUTHOR]

The oxidation of ammonium sulfite obtained from ammonia-based flue gas desulfurization by hydrogen peroxide in aqueous solutions was studied using a stirred reactor. An experimental study of the kinetic parameters of the oxidation process was investigated in the pH of 4.2–5.2 at 25–50°C. $r = {k_3}\left[{{H^ + }} \right]\left[{HSO_3^ - } \right]\left[{{H_2}{O_2}} \right]$ r = k 3 H + HS O 3 − H 2 O 2 is valid at sulfite concentrations of 10−4 mol/L for the pH range 4.2–5.2. At 298K and pH of 5.0, third-order rate constant k3 was found to be (6.9 ± 0.21)×107 (mol/L)−2s−1. When the concentration of sulfite is 0.01 mol/L, the reaction first-order with respect to sulfite and hydrogen peroxide, and the second-order reaction rate constant at pH of 4.2–5.4 is $\lg {k_2} = - 1.0135pH + 7.4862$ lg k 2 = − 1.0135 pH + 7.4862. Activation energy of Ea = 32.26 kJ/moL. Kinetic data were compared with previous studies. A semi-empirical formula can express the effect of ionic strength on k3. The kinetic data of ammonium sulfite oxidation with hydrogen peroxide have potential applications in the wet ammonia desulfurization process. [ABSTRACT FROM AUTHOR]

The sluggish kinetics of methanol oxidation reaction (MOR) required high‐performing catalysts in the development of direct methanol fuel cells. Herein, a phosphorus‐doped MoO2 nanorods‐supported Pt catalyst was proposed which exhibited remarkably enhanced catalytic performance toward MOR in comparison with Pt/MoO2 and commercial Pt/C. Specifically, the Pt/MoO2‐P possessed the highest peak current density of 62.63 mA cm−2, about 1.38 and 2.21 times higher than that of Pt/MoO2 (45.24 mA cm−2) and Pt/C (28.40 mA cm−2), respectively. Meanwhile, the Pt/MoO2‐P possessed high intrinsic activity expressed by specific activity and mass activity, and largely improved catalytic kinetics. Moreover, the chronoamperometry and CO‐stripping testing successfully revealed the superior stability and CO‐poisoning resistance of Pt/MoO2‐P, rendering Pt/MoO2‐P a promising catalyst for MOR. The theoretical calculation revealed the electron redistribution and strong metal‐support interaction among Pt/MoO2‐P catalysts. The greatly enhanced catalytic performance could be attributed to the heteroatom doping engineering, greatly enhancing the conductivity, and inducing electron redistribution, thereby leading to the strong metal‐support interaction and high CO‐anti poisoning ability. [ABSTRACT FROM AUTHOR]

Electromagnetic wave (EMW) absorbing materials play an increasingly crucial role in mitigating electromagnetic pollution. In this study, the laser‐induced self‐propagating synthesis (LSS) method was employed to successfully produce Al3BC3 powders with a purity of up to 98.8 wt.% using aluminum powder, boron carbide powder, and carbon powder as raw materials. The preparation efficiency was increased by approximately 20–360 times compared to conventional heating methods. Additionally, the as‐synthesized Al3BC3 powder exhibited remarkable oxidation resistance, with an apparent oxidation activation energy (E) of 213.04 kJ/mol and a preexponential factor of 5.38. Moreover, the powder demonstrated superior EMW absorption performance at 973 K, with a reflection loss below –10 dB within the frequency range of 6.74–7.97 GHz and a minimum reflection loss reaching –45.86 dB at a thickness of 2.9 mm. These results suggest that the as‐synthesized Al3BC3 powder is a promising candidates for high‐temperature EMW absorption applications. [ABSTRACT FROM AUTHOR]

AbstractThe oxidation of [RuII(pic)3]- (pic- = picolinate) with peroxydisulfate (S2O82-) was studied spectrophotometrically and kinetically in aqueous solution. The rate of the reaction followed via absorbance at 466 nm (a metal-to-ligand charge transfer band of [RuII(pic)3)]-) and was found to be first-order in the Ru(II)-complex. The values of the observed rate constant (kobs) increased linearly with an increase in [S2O82-]. The rate of the reaction was found to be independent of pH in the studied range of 3.0 to 7.5. Alkali metal ions were found to have a positive influence (K+ > Na+ > Li+) on the rate of the oxidation. Kinetic data and activation parameters (ΔH≠ = 37 ± 1 kJ mol−1 and ΔS≠ = −129 ± 3 J mol−1 deg−1) are interpreted in terms of a mechanism involving outer-sphere electron transfer between the reaction partners. A detailed reaction mechanism in agreement with the spectral and kinetic data is presented and discussed with reference to that reported for the oxidation of [RuII(pic)3]- with H2O2. [ABSTRACT FROM AUTHOR]

A pulsed electrodeposition was performed on mild steel surfaces to prepare Ni-W-based composite coatings consisting of TiO2 and ZrO2 oxide nanoparticles. To evaluate the oxidative properties of coatings, isothermal oxidation studies were performed on the coatings at 873, 973, and 1073 K in the air for 30 h. The coatings' phase evolution, morphology, and chemistry were investigated by x-ray diffraction, field emission scanning electron microscopy, and energy-dispersive spectroscopy, respectively. As a result of examining the microstructure changes after the oxidation test, it was found that the oxide formation increased according to the oxidation temperature. To determine the oxidation kinetics of the respective coatings, Arrhenius plots were drawn and activation energies were calculated. The final results confirmed that the oxidation resistance of the Ni-W-TiO2-ZrO2 nanocomposite coatings (NiWNC) increased with the addition of ZrO2 (0 − 15 g/L). In this study, better oxidation resistance was observed for the Ni-W-5 g/L TiO2-15 g/L ZrO2 nanocomposites compared to the rest of the coatings. These findings highlight the potential of producing highly oxidation-resistant coatings using a cost-effective method on commercially available metal surfaces such as mild steels. [ABSTRACT FROM AUTHOR]

The macroscopic and microscopic surface morphology, products, kinetics, and reaction mechanism of one typical aero-engine material 0Cr18Ni9 in the cases of high-temperature oxidation and hot corrosion by a novel superhydrophobic and oleophobic ultrafine dry powder extinguishing agent (SHOU DPEA) are studied in a simulated aircraft engine compartment working environment. The results demonstrate that the oxidation and corrosion products both contain FeCr2O4, Fe2O3, and Fe3O4. However, the presence of SHOU DPEA accelerates the corrosion within the alloy. The 0Cr18Ni9 substrate shows a L-shaped segregation phenomenon and a chromium-poor layer. Furthermore, the oxidation and corrosion kinetic curves of 0Cr18Ni9 are both parabolic. In particular, the high-temperature oxidation behavior of 0Cr18Ni9 can be divided into two stages: a rapid oxidation stage (0-96 hours) and an oxidation equilibrium stage (96-192 hours), and the hot corrosion process can be divided into two stages: an initial slow incubation stage from 0 to 48 hours, and an accelerated corrosion stage from 48 to 192 hours. Additionally, the chemical reaction mechanisms for oxidation/corrosion are illustrated. [ABSTRACT FROM AUTHOR]

As part of advancing oxygen–hydrogen combustion power generation technology, a study was carried out to evaluate the oxidation behavior of a novel developed Ni–Cr–W alloy as the structural material candidate. Tungsten is utilized in the alloy as a solid solution-strengthened element and as an α2-W precipitate former. The examination involved exposing the developed alloy and commercial alloys, Hastelloy X and Nimonic 263, to air and steam environments at 1273 K. The results show a different oxidation behavior of the developed alloy. Considering the air oxidation kinetics, the performance of the developed alloy was on par with that of Hastelloy X and superior to Nimonic 263. A single outer chromia scale was established with an intergranular oxide. Whereas steam exposure resulted in the formation of outer and inner chromia scales with a deeper intergranular oxide penetration. Thicker chromia formation with a lower mass gain indicates the evaporation of chromia under a steam atmosphere. [ABSTRACT FROM AUTHOR]