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CuO nanoparticles (NPs) stand out due to their inherent antibacterial activity, cost-effectiveness, and tunable bandgap, rendering them promising for medical, disinfection, environmental, and industrial applications. Our study aimed to synthesize CuO NPs using fish scale (FS) waste and assess the impact of calcination temperature (100 °C, 300 °C, 500 °C, and 700 °C) on their structural and antibacterial properties. XRD analysis confirmed the formation of monoclinic structured CuO, corroborated by XPS analysis indicating a Cu2+ oxidation state. Crystallographic parameters such as lattice dimensions, the volume of the unit cell, the density of the unit cell, micro-strain, and dislocation density for all four CuO NP samples were calculated using established equations. The crystallite size was estimated by employing the Scherrer equation, linear straight-line method (LSLM), Williamson–Hall (W–H) method, Halder–Wagner (H–W) method, Monshi–Scherrer (M–S) method, and size–strain plot (SSP) method. Based on the highest value of the coefficient of determination (R2), the appropriateness of the measurement techniques was determined, and the crystallite sizes were found to be 10 nm, 11 nm, 24 nm, and 35 nm, respectively. The particle size was estimated based on the FESEM and TEM images, both of which showed an increase in size with calcination temperature. FTIR detected the presence of amide bands, which originated from the FS, and the EDX analysis provided qualitative and quantitative elemental measurements. The antibacterial activity was investigated against two Gram-negative (E. coli and S. typhi) and two Gram-positive (B. megaterium and S. aureus) bacterial strains. Increasing the calcination temperature resulted in increased particle size, which led to reduced antibacterial activity. [ABSTRACT FROM AUTHOR]

A series of Ni-substituted LaCu1-xNixO3 (x = 0, 0.1, 0.3, 0.5 and 0.7) catalysts were prepared by a mechanochemical synthesis method and the prepared samples were used in catalytic combustion of methane. The catalytic results indicated that the partial substitution of Ni affected the catalytic performance and the increase in nickel content increased the catalytic activity and among the prepared catalysts the LaCu0.5Ni0.5O3 sample possessed the highest catalytic activity and thermal stability. The results showed that methane conversion reached from 7.8 to 73.8% at 500 °C with the substitution of Ni in the amount of x = 0.5. Also, the addition of Ni instead of Cu in the LaCu1-xNixO3 led to an increase in total pore volume and specific surface area and a decrease in average crystalline size. According to O2-TPD profiles of the LaCu1-xNixO3 catalysts, mobility of lattice oxygen (O2−) has a crucial role in determining the performance of these catalysts. The H2-TPR results indicated that the addition of Ni slightly improved the reducibility of catalysts. Furthermore, a decrease in calcination temperature of LaCu0.5Ni0.5O3 catalyst resulted in an increase in the catalytic activity due to the enhancement in the concentration of oxygen vacancy and specific surface area. Also, the results revealed that the increase in feed ratio (CH4/O2) leads to an increment in methane conversion. [ABSTRACT FROM AUTHOR]

The interaction between refractories and molten steel in tundish has significant influence on quality of steel. The calcined dolomite and fused magnesia were adopted as raw materials to prepare MgO–CaO based refractories for tundish. Then the reaction behavior between refractories with different contents of calcined dolomite and molten steel was investigated. After reaction with different refractories at 1550 °C for 90 min, the total O and P in steels reduced by 33.9 % and 77 % respectively when increasing calcined dolomite from 0 to 60 wt%, the average size and area proportion of inclusions decreased from 4.92 μm and 9.98 ‰ to 2.47 μm and 4.73 ‰ respectively. Inclusions of FeO wrapped by FeO–P 2 O 5 –MnS translated to FeO coated by FeO–MnS. The CaO introduced by calcined dolomite could reduce the increase of oxygen to molten steel owing to better thermodynamic stability compared with MgO. Meanwhile, CaO could absorb [P] to form Ca 3 (PO 4) 2 on the surface of calcined dolomite particles, which was beneficial for dephosphorization of molten steel. [ABSTRACT FROM AUTHOR]

This paper has successfully employed a hydrothermal method to synthesize spinel LiMn1.5Ni0.5O4 (LMNO) cathode materials. Calcination at 600, 700, and 800 °C is performed to evaluate microstructure properties compared to as-prepared LMNO. The samples are investigated by XRD, SEM, TGA, FTIR. The crystallite sizes are smaller than the particle size of LMNO, revealing their polycrystalline nature. The TGA analysis supports the structural changes after calcined as revealed by XRD spectra. The FTIR spectrum indicates that the LMNO disorder-order transition occurs within the investigated temperature range. The peak broadening is attributable to the contribution of crystallite size and lattice strain, further analyzed according to Scherrer, Williamson-Hall, Size-Strain plot, and Halder-Wagner methods. Additionally, the results gained from different analysis methods are contrasted and discussed, which is the primary focus of this study. Generally, all analysis models indicate that the crystallite grows monotonously larger as temperature increases. The lowest lattice strain is observed in the as-prepared LMNO. However, calcining at 600 °C exhibits the highest developed lattice strain and gradually decreases as temperature increases further. This study also highlights the importance of convolution of size and strain contributions in determining the suitable method for calculating crystallite size and lattice strain. [ABSTRACT FROM AUTHOR]

This article discusses the thermal technological processes occurring in petroleum coke calcination furnaces, as well as issues of causes of destruction of the refractory material of the calcination furnace lining. The survey showed that the main factors influencing the duration of the work campaign of the lining are the temperature stresses that arise in the lining during sudden temperature changes during heating or cooling, as well as the chemical effect of the process material on the lining. It was revealed that in the inlet zone, where the drying of technological raw materials is carried out, the wear of the lining occurs evenly, and there is no significant damage. On thermal imaging images, this zone is displayed as uniform temperature fields on the outer surface of the furnace. In the calcination zone, the lining is characterized by the presence of main cracks that run along the seams. These cracks indicate the occurrence of significant thermal stresses when the furnace is heated. Work was done to determine the dependence of tensile strength on temperature, in the temperature range from 20 °C to 650 °C. Analysis of the results of determining the tensile strength showed a general tendency for it to increase with increasing temperature. This is explained by changes in the structure of the refractory material with increasing temperature and load. Taking into account the obtained dependence of the tensile strength on temperature allows one to adjust the heating schedules of the calcination furnace to reduce the temperature stress during the heating process. [ABSTRACT FROM AUTHOR]

Doping Sr has the potential to enhance bioceramic properties. However, controlling purity, Sr concentration, and properties is crucial. Therefore, precise evaluation of synthesis variables is essential, achieved through experimental design techniques. This study synthesized Sr-doped calcium silicate wollastonite using a Plackett–Burman design with 11 variables to identify key factors affecting synthesis yield and physical, structural, and chemical attributes for tissue engineering. Results indicate that the strontium proportion significantly impacts material properties, affecting porosity, surface area, and pore volume. Moreover, observations reveal that calcination temperature contributes to heightened crystallinity and strontium doping. Adjusting calcium and strontium precursor concentrations while reducing the silicon to calcium and strontium ratio improves efficiency crystallinity, purity, and promotes the formation of the preferred β-CaSiO 3 phase. Overall, consistent and reproducible findings provide valuable insights into the variables influencing the process and facilitate optimization for future ceramic synthesis. [Display omitted] [ABSTRACT FROM AUTHOR]

The catalytic efficiency of CeO2 in soot oxidation was significantly affected by its grain morphology and calcination temperature. Nanocube-shaped and nanorod-shaped CeO2 catalysts were synthesized via a hydrothermal method with different calcination temperatures. Activity tests revealed that the nanorod-shaped CeO2 exhibited superior catalytic activity compared to the nanocube-shaped catalysts at equivalent calcination temperatures. Furthermore, an inverse relationship between the catalytic activity and the calcination temperature was observed in the nanorod-shaped CeO2 catalysts, with those calcined at 300 °C exhibiting the most effective low-temperature catalytic performance. Combined characterization techniques and density functional theory calculations showed that the improved catalytic performance can be attributed to the increased abundance of oxygen vacancies, enhanced lattice oxygen mobility and higher surface energy due to their unique surface defect structure and electronic structural feature, in addition to the reduction in grain size. [ABSTRACT FROM AUTHOR]

Gadolinium Zirconate nanoparticles were synthesized by Co-precipitation and Ball milling techniques. In this study, the effect of the synthesis technique and calcination temperature on the structural, morphological and thermal properties were investigated. The thermal properties examined showed that the GZ nanoparticles obtained from CP technique suffered two-fold weight loss as compared to BM technique. The SEM results revealed the formation of agglomerated particles. However, TEM results confirms the formation of nanoparticles of 10.5 nm and 8 nm by BM and CP techniques respectively. GZ particles obtained through CP technique showed better uniformity of particle size over BM technique. The functional groups of the nanoparticle were studied using FT-IR spectroscopy analysis. The XRD results confirm the formation of defect-fluorite structure and pyrochlore structure for the samples calcined at 1100 °C and 1400 °C (BM) respectively. The formation of the corresponding structures was further confirmed by Raman Spectroscopy. The thermal conductivity of the nanoparticle produced by ball milling and co-precipitation technique is almost same. As compared to NiCrAlY and uncoated substrate materials, the micro hardness of the GZ coatings has the maximum hardness of 594.6 HV, indicating the improved hardness behavior of TBC system. [ABSTRACT FROM AUTHOR]

For the first time, it is discovered that the calcination products of the mixture containing titanium dioxide (TiO 2) and cuprous chloride (CuCl) were a novel kind of anode materials of LIBs. Herein, a mixture containing TiO 2 and CuCl with a Ti/Cu mole ratio of 2:1 was calcined at different temperatures in air to harvest the samples. The samples sintered at 350°C, 400°C and 450°C were respectively classified as sample a, b and c. As analyzed, TiO 2 , CuO and CuCl 2 were the principal components of all resultant samples. Interestingly, as compared to the pure TiO 2 , all prepared samples, especially sample b, delivered a markedly enhanced electrochemical property. For instance, the initial DC (discharge capacity) of sample b at 0.1 A g−1 was 487 mAh g−1, being much better than that of sample a, c and the pure TiO 2 (sample o). Impressively, the DC value of sample b was around 101 mAh g−1 at 1.0 A g−1 after 100 cycles, which, respectively, was about 1.5, 2.0 and 5.3 times that of sample a (66 mAh g−1), c (49 mAh g−1) and o (19 mAh g−1). After a thorough investigation, the reduced R ct and the evidently increased D Li+ were considered as the main causes providing all samples, especially sample b, a satisfied electrochemical performance. To summarize, the electrochemical properties of all as-produced samples were better than that of the pure TiO 2. That is, a groundbreaking concept, that using a calcination product containing TiO 2 , CuO and CuCl 2 rather than a pure substance as the anode materials of LIBs, was developed here. [ABSTRACT FROM AUTHOR]

This study focuses on the synthesis of a monocarboaluminate (MCA)-based binder by treating marble waste (MW) powder with sodium aluminate (SA). The aim is to investigate the influence of various parameters, including the alumina modulus (MA) of SA, different contents of calcined clays with varying alumina levels, and curing temperatures, on the performance and phase composition of the resulting binder. The results demonstrate that the combination of SA and MW leads to the formation of an MCA-based binder, which exhibits a high compressive strength of up to 28 MPa after seven days of curing. Additional phases such as gibbsite, pirssonite, and gaylussite are observed, indicating the occurrence of a cationic exchange reaction between MW and SA, as confirmed by X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FT-IR). The stability of the resulting binder is primarily influenced by the MA value, with higher values associated with greater stability. Regardless of the type of calcined clay used, incorporating calcined clay results in the formation of a calcium aluminate silicate hydrate (CSAH) phase alongside MCA, contributing to the improved stability of the hardened binder over time. Notably, calcined clay with a higher alumina content exhibits the highest strength at all curing ages. Furthermore, increasing the curing temperature up to 100 °C significantly enhances the early strength, which correlates with the formation of the kotoite phase at the expense of the MCA phase. [ABSTRACT FROM AUTHOR]

Converting carbon dioxide into valuable chemicals requires suitable catalysts to perform efficiently under severe reaction conditions. Developing suitable supported copper catalysts can potentially improve catalytic performance for CO 2 reduction by interacting with copper active components. Herein, we investigate Cu/ZrO 2 catalysts, synthesized by wet-impregnation (WI) method with various copper contents, for the reverse water-gas shift (RWGS) reaction. It is anticipated that metal-support interaction, surface defects, and oxygen vacancies in oxide catalysts play critical roles in defining catalytic activity. To understand this, various ZrO 2 -supported catalysts with different crystallite sizes were prepared by altering the calcination temperature and assessing their catalytic performance. The results showed that 2 wt%Cu/ZrO 2 catalyst calcined at 800 °C had the highest CO 2 conversion to CO of ∼37 % at 600 °C, with less than 0.25 % coke formation. Kinetics studies showed that the redox model agreed better with experimental data when considering equilibrium conditions. [Display omitted] • Volcano correlations in CO 2 conversion curves with peaks at 2 wt%Cu and 800 °C. • Better reducibility, high dispersion, and stronger MSI in 2 wt%Cu/ZrO 2 -800 sample. • ZrO 2 phase change from monoclinic to tetragonal by raising calcination temperature. • 37 % conversion at 600 °C with 2 wt%Cu/ZrO 2 -800 catalyst, stable for 72 h TOS. • Redox mechanism of the 2 wt%Cu/ZrO 2 -800 catalyst in RWGS, based on kinetic studies. [ABSTRACT FROM AUTHOR]

High-performance hydrogen sulfide (H2S) sensors are mandatory for many industrial applications. However, the development of H2S sensors still remains a challenge for researchers. In this work, we report the study of a TiO2-based conductometric sensor for H2S monitoring at low concentrations. TiO2 samples were first synthesized using the sol-gel route, annealed at different temperatures (400 and 600 °C), and thoroughly characterized to evaluate their morphological and microstructural properties. Scanning electronic microscopy, Raman scattering, X-ray diffraction, and FTIR spectroscopy have demonstrated the formation of clusters of pure anatase in the TiO2 phase. Increasing the calcination temperature to 600 °C enhanced TiO2 crystallinity and particle size (from 11 nm to 51 nm), accompanied by the transition to the rutile phase and a slight decrease in band gap (3.31 eV for 400 °C to 3.26 eV for 600 °C). Sensing tests demonstrate that TiO2 annealed at 400 °C displays good performances (sensor response Ra/Rg of ~3.3 at 2.5 ppm and fast response/recovery of 8 and 23 s, respectively) for the detection of H2S at low concentrations in air. [ABSTRACT FROM AUTHOR]

Due to their tremendous industrial, environmental, and biological applications, research focusing on the synthesis and applications of silver nanoparticles (Ag NPs) has attracted increased interest from researchers over the past two decades. Their structural as well as textural properties can be easily tuned depending on the synthesis protocol utilized. Combustion synthesis has received increased attention as a one-pot route for the synthesis of a wide spectrum of nanomaterials. In this study, we present the results of synthesizing Ag NPs employing urea as a combustion fuel. The effect of the temperature of calcination on the formation and structural features of Ag NPs has been checked over the 400–700 °C temperature range. The characterization of the synthesized Ag NPs has been performed using XRD, SEM, TEM, and XPS techniques. It was found that Ag NPs, with a crystallite size of 40 nm, start to form at around 400 °C. Conducting the calcination at the 500–700 °C range results in the persistence of the obtained Ag NPs. Moreover, the obtained nanomaterials are characterized by a membrane-like morphology. The activity performance of the synthesized Ag NPs was examined for the hydrolysis of sodium borohydride (NaBH4) over a temperature range of 35–50 °C. Increasing the calcination temperature has led to a decrease in the activity of the Ag NPs during the NaBH4 hydrolysis. [ABSTRACT FROM AUTHOR]

[Display omitted] • Glass fiber wind turbine blades (WTBs) can provide raw material to produce cement. • Glass fiber WTBs can serve as fuel and replace coal to produce cement. • High boron in some glass fiber WTBs might limit replacement rates. • Combustion of fossil-fuel polymer in WTBs can slightly reduce plant CO 2 emissions. • Glass fiber wind turbine blades are compatible with the cement production process. The objective of this paper is to evaluate the feasibility of co-processing wind turbine blade (WTB) material in cement manufacturing to provide an end-of-life means to divert the solid waste of decommissioned WTBs from landfills. Many WTBs consist primarily of glass fiber reinforced thermoset polymers that are difficult to recover or recycle. Portland cement is produced world-wide in large quantities, requiring immense quantities of raw materials (mostly calcium oxide and silicon oxide) and kiln temperatures approaching 1,450 °C. This work contributes analyses of WTB material composition, and predicts the energy provided through the combustible components of the WTBs and raw material contributions provided by incorporating the incombustible components of the WTBs to produce cement. Approximately 40 to 50 % of the WTB material will contribute as fuel to cement production, and approximately 50 to 60 % of the WTB material is expected to be incombustible. One tonne of WTB material can displace approximately 0.4 to 0.5 tonne of coal, while also contributing approximately 0.1 tonne of calcium oxide and 0.3 tonne of silicon oxide as raw material to the cement production process. The glass fiber WTB tested had an average boron content of 4.5 % in the ash. The effects of this high boron content on the cement and its production process should be evaluated. Co-processing WTBs in cement plants will slightly reduce combustion-related CO 2 emissions due to avoided calcination. It seems feasible to co-process glass-fiber reinforced WTBs in cement production as WTBs provide suitable raw materials and compatible fuel for this process. [ABSTRACT FROM AUTHOR]

Iron red, a traditional Jingdezhen overglaze color, is primarily colored with iron oxide (Fe2O3). In traditional processes, the main ingredient for the iron red overglaze color, raw iron red, is produced by calcining iron vitriol (FeSO4·7H2O). Analysis of ancient iron red porcelain samples indicates that the coloration is unstable, ranging from bright red to dark red and occasionally to black. Addressing this, the present study, from a ceramic technology standpoint, conducts a series of calcination experiments on industrial iron vitriol at varying temperatures. Utilizing methodologies such as differential scanning calorimetry-thermogravimetry (DSC-TG), Raman spectroscopy, X-ray diffraction (XRD), scanning electron microscopy with X-ray energy dispersive spectrometry (SEM-EDS), and optical microscopy (OM), this research scientifically explores the impact of iron vitriol's calcination temperature on the coloration of traditional Jingdezhen iron red overglaze color. The findings indicate that from room temperature to 550 °C, the dehydration of iron vitriol resulted in the formation of Fe2(SO4)3 and a minimal amount of α-Fe2O3, rendering the iron red overglaze color a yellowish-red shade. At 650 °C, the coexistence of Fe2(SO4)3 and α-Fe2O3 imparted a brick-red color to the iron red. As the temperature was elevated to 700 °C, the desulfurization of Fe2(SO4)3 produced α-Fe2O3, transitioning the iron red to an orange red. With further temperature increase to 750 °C, the particle size of α-Fe2O3 grew and the crystal reflectivity decreased, resulting in a purplish-red hue. Throughout this stage, the powder remained in a single α-Fe2O3 phase. Upon further heating to 800 °C, the crystallinity of α-Fe2O3 enhanced, giving the iron red overglaze color a dark red or even black appearance. [ABSTRACT FROM AUTHOR]

Self-made agglomerated nanometer CeO2-Y2O3-ZrO2 (CYSZ) powders for plasma spray–physical vapor deposition (PS-PVD) were prepared by spray-drying, followed by calcination treatment at four different temperatures (600 °C, 700 °C, 800 °C, 900 °C). The physical properties, microstructure, and phase composition of the calcined powders were investigated using a laser particle size analyzer, scanning electron microscopy (SEM), and X-ray diffraction (XRD). The results showed that compared to the agglomerated powders obtained through spray-drying, the particle size of the agglomerated powders changed with increasing calcination temperature, accompanied by an increase in the self-bonding force of the agglomerated powder particles. The proper calcination temperature improved the sprayability of the powders. Additionally, with the increase in the calcination temperature, a transformation from the m-phase to the t-phase occurred in the powder, with Ce4+ partially entering the Zr lattice to form the t-Zr0.84Ce0.16O2 phase, which facilitated the suppression of the m-phase and improved the high-temperature phase stability. It was also found that the PS-PVD coatings prepared using the aforementioned powders exhibited coarser columnar structures with increasing powder calcination temperature. [ABSTRACT FROM AUTHOR]

Using magnetic nanoparticles (MNPs) for extracorporeal heating applications results in higher field strength and, therefore, particles of higher coercivity can be used, compared to intracorporeal applications. In this study, we report the synthesis and characterization of barium hexa-ferrite (BaFe12O19) nanoparticles as potential particles for magnetic heating. Using a precipitation method followed by high-temperature calcination, we first studied the influence of varied synthesis parameters on the particles' properties. Second, the iron-to-barium ratio (Fe/Ba = r) was varied between 2 and 12. Vibrating sample magnetometry, scanning electron microscopy and X-ray diffraction were used for characterization. A considerable influence of the calcination temperature (Tcal) was found on the resulting magnetic properties, with a decrease in coercivity (HC) from values above 370 kA/m for Tcal = 800–1000 °C to HC = 45–70 kA/m for Tcal = 1200 °C. We attribute this drop in HC mainly to the formation of entirely multi-domain particles at high Tcal. For the varying Fe/Ba ratios, increasing amounts of BaFe2O4 as an additional phase were detected by XRD in the small r (barium surplus) samples, lowering the particles' magnetization. A decrease in HC was found in the increased r samples. Crystal size ranged from 47 nm to 240 nm and large agglomerates were seen in SEM images. The reported particles, due to their controllable coercivity, can be a candidate for extracorporeal heating applications in the biomedical or biotechnological field. [ABSTRACT FROM AUTHOR]

This study focuses on the utilization of activated carbon (AC) as a catalyst support after undergoing treatment with HNO 3. The treated AC exhibited a microporous structure and a high specific surface area (S BET) of 1483.8 m2 g−1. In this study, supported nickel-based catalysts were synthesized using the wet impregnation method with varying amounts of NiO (2.5, 5, 7.5, 10, 12.5, and 15 wt%). The calcined catalyst samples were then evaluated for their performance in the dry reforming of methane (DRM). Characterization of the catalysts was conducted through FESEM, TPO, H 2 -TPR, XRD, and N 2 adsorption-desorption (BET) analyses. The results revealed that catalytic efficiency increased with an increase in the nickel loading percentage, up to 12.5 wt%. The NiO (12.5)/AC catalyst demonstrated the highest CH 4 (60%) and CO 2 (68%) conversions and exhibited good stability at 700 °C during 10 h of reaction. Additionally, the catalyst's efficiency decreased with an increase in the calcination temperature from 400 to 600 °C. However, alterations in the CH 4 /CO 2 molar ratio from 0.5 to 1.5 indicated that CH 4 and CO 2 conversions decreased from 85% to 40% and increased from 63% to 74% at 700 °C, respectively. Moreover, the findings demonstrated that elevating the gas hourly space velocity (GHSV) from 12,000 to 18,000 ml h−1.g−1 cat resulted in a decline in catalytic efficiency at a temperature of 700 °C. Moreover, the catalytic efficiency declined with an increase in the reduction temperature from 500 to 600 °C. [Display omitted] • AC treated with HNO 3 exhibited a high surface area (1483.8 m2/g), making it an ideal catalyst support. • The NiO (12.5)/AC catalyst showed high performance, achieving conversions of CH 4 (60%) and CO 2 (68%) at 700 °C in DRM. • Higher T calcination altered the catalyst's morphology and increased the size of nickel particles. [ABSTRACT FROM AUTHOR]

The present work reported the bioinspired synthesis of Bi2O3 nanoparticles (NPs) using Ziziphus mauritiana leaves aqueous extract at four annealing temperatures (300, 400, 500, and 600C°) and examined annealing temperatures effect of on various physicochemical characteristics and photocatalytic activities of NPs. The XRD and Raman results reveal the existence of α and β polymorphs of Bi2O3 in all samples but with increase of calcination temperature the extent of α-phase, particle size, and crystallinity were increased while band gap value decreased. The BET results confirmed the mesoporous structure of all samples. Further, decolorization experiments conducted with crystal violet (CV) dye showed an observable effect of annealing temperature on the adsorption and photocatalytic efficacy of the prepared samples, and the utmost (99.88 %) removal of CV dye was computed with the Bi2O3 nanoparticles calcined at 300oC (B-300). The main active species involved in the photo-mineralization of dye was h+ followed by •OH.. [ABSTRACT FROM AUTHOR]

• Ru-Na 2 CO 3 -CaO/Al 2 O 3 DFMs for CO 2 adsorption and hydrogenation to CH 4 are synthesized. • DFMs are subjected to different calcination protocols in static or dynamic streams. • The calcination atmosphere influences the DFM physicochemical properties. • Calcination under N 2 stream accommodates better the adsorbent and Ru phases. • RuNaCa-N 2 is most efficient for CH 4 production (449 µmol g−1 at 370°C) with high selectivity. Integrated CO 2 capture and utilization (ICCU) technology requires dual functional materials (DFMs) to carry out the process in a single reaction system. The influence of the calcination atmosphere on efficiency of 4% Ru-8% Na 2 CO 3 -8% CaO/γ-Al 2 O 3 DFM is studied. The adsorbent precursors are first co-impregnated onto alumina and calcined in air. Then, Ru precursor is impregnated and four aliquotes are subjected to different calcination protocols: static air in muffle or under different mixtures (10% H 2 /N 2 , 50% H 2 /N 2 and N 2) streams. Samples are characterized by XRD, N 2 adsorption-desorption, H 2 chemisorption, TEM, XPS, H 2 -TPD, H 2 -TPR, CO 2 -TPD and TPSR. The catalytic behavior is evaluated, in cycles of CO 2 adsorption and hydrogenation to CH 4 , and temporal evolution of reactants and products concentrations is analyzed. The calcination atmosphere influences the physicochemical properties and, ultimately, activity of DFMs. Characterization data and catalytic performance discover the acccomodation of Ru nanoparticles disposition and basic sites is mostly influencing the catalytic activity. DFM calcined under N 2 flow (RuNaCa-N 2) shows the highest CH 4 production (449 µmol/g at 370°C), because a well-controlled decomposition of precursors which favors the better accomodation of adsorbent and Ru phases, maximizing the specific surface area, the Ru-basic sites interface and the participation of different basic sites in the CO 2 methanation reaction. Thus, the calcination in a N 2 flow is revealed as the optimal calcination protocol to achieve highly efficient DFM for integrated CO 2 adsorption and hydrogenation applications. [Display omitted] [ABSTRACT FROM AUTHOR]

In this study, the best conditions for synthesizing the cobalt oxide nanofibers using the electrospinning method was investigated. For this purpose, the effect of various factors such as solvent, calcination temperature, and polymer concentration on the crystal structure, morphology, and size of the synthesized samples was evaluated. An extensive characterization of the products was performed using x‐ray diffractometry, scanning electron microscopy, ultraviolet‐visible spectroscopy, and photoluminescence. X‐ray diffractometry results of fabricated samples at different temperatures confirm cobalt oxide synthesis. Scanning electron microscopy analysis shows that the best fibers are synthesized from a polymer solution prepared at room temperature with a dual solvent of deionized water and ethanol under a calcination temperature of 600 °C. Also, some shifts were observed by examining the optical properties using ultraviolet‐visible and photoluminescence spectroscopy. These results show that the proper selection of reaction conditions in the electrospinning method can be very effective for the synthesis of cobalt oxide fibers with morphology in nanometer sizes. [ABSTRACT FROM AUTHOR]

The heat treatment condition has been known to have significant influence on the catalysts applied in high-temperature application. In this work, after studying the effect of Ni loading on ZrO2 in CO2 methanation reaction, the effect of calcination and reduction treatment on the characterization and catalytic activity was investigated. The catalysts were characterized by X-ray diffraction, energy-dispersive X-ray spectroscopy, scanning electron microscopy, high-resolution transmission electron microscopy (HR-TEM), thermogravimetric analysis-DSC, isotherm N2 adsorption, H2 temperature program reduction, CO2 temperature program desorption and Raman spectroscopy. By studying different nickel loading, heat treatment temperatures and duration, these factors were found out to have correlation with the ZrO2 phases formation (tetragonal ZrO2 phase and monoclinic ZrO2 phase). Changing the calcination and reduction condition can alter the surface morphology, ZrO2 phase composition, the crystal sizes of ZrO2, NiO and Ni, as well as metal–support interaction, which can further improve the performance of the catalysts. Suitable heat treatment mode showed the ability to induced higher catalytic conversion of CO2 (70% at 400 °C) in the CO2 methanation. The superior catalytic activity was subjected to the enhanced reducibility of NiO species and the improved Ni dispersion and subjected to the co-existence of m-ZrO2 and t-ZrO2. Furthermore, the as-synthesized Ni/ZrO2 catalyst with higher specific surface area (26.2 m2/g) than several other literature's catalysts and an apart of Ni embedded in the ZrO2 pores exhibited good stability and high coke resistance, subjected to a 2.041% coke deposition after 100 h on stream. [ABSTRACT FROM AUTHOR]

Lightweight ceramic proppants are prepared using coal gangue, fly ash, and bauxite as raw materials, and a mixture of manganese dioxide and magnesium oxide is used as composite additives. The total content of the coal gangue and fly ash in the raw materials reaches up to 70 wt%. The effects of coal gangue and fly ash precalcination, sintering temperature, and composite additive content on the phase compositions, microstructures, and performances of the resulting ceramic proppants are studied in detail. The ceramic proppant prepared at 1285 °C using 1 wt% of the composite additive is composed of quartz, corundum, and mullite. It also presents the desired sphericity, roundness, and microstructure. The apparent density, bulk density, and breakage ratio of the ceramic proppant described above are 2.55 ± 0.06 g/cm3, 1.03 ± 0.02 g/cm3, and 8.30 ± 0.68% at 35 MPa, respectively. This ceramic proppant belongs to lightweight ceramic proppants and meets the requirement of the 5K grade in the standards of SY/T 5108-2014 and API STD 19C-2018. [ABSTRACT FROM AUTHOR]

The recycling of graphite from spent lithium-ion batteries (LIBs) is overlooked due to its relatively low added value and the lack of efficient recovering methods. To reuse the spent graphite anodes, we need to eliminate their useless components (mainly the degraded solid electrolyte interphase, SEI) and reconstruct their damaged structure. Herein, a facile and efficient strategy is proposed to recycle the spent graphite on the basis of the careful investigation of the composition of the cycled graphite anodes and the rational design of the regeneration processes. The regenerated graphite, which is revitalized by calcination treatment and acid leaching, delivers superb rate performance and a high specific capacity of 370 mAh g-1 (~99% of its theoretical capacity) after 100 cycles at 0.1 C, superior to the commercial graphite anodes. The improved electrochemical performance could be attributed to unchoked Li+ transport channels and enhanced charge transfer reaction due to the effective destruction of the degraded SEI and the full recovery of the damaged structure of the spent graphite. This work clarifies that the electrochemical performance of the regenerated graphite could be deteriorated by even a trace amount of the residual “impurity” and provides a facile method for the efficient regeneration of graphite anodes. [ABSTRACT FROM AUTHOR]

In order to improve the treatment effect of dielectric barrier discharge (DBD) on chlorinated volatile organic compounds (CVOCs), the NiO/α-Mn3O4 composite catalyst was prepared by co-precipitation method, and the gaseous o-chlorotoluene was catalyzed by DBD. The catalyst was characterized by X-ray diffraction (XRD), scanning electron microscope (SEM), and specific surface area and aperture analyzer (BET). The effects of gas flow rate, applied voltage, initial concentration, and relative humidity on the degradation efficiency and energy yield of o-chlorotoluene were investigated. The results showed that the NiO/α-Mn3O4 composite catalyst had the best catalytic performance when the molar ratio of Ni/Mn was 0.3 and the calcination temperature was 400 °C. When the initial concentration of o-chlorotoluene was 140 mg/m³, the applied voltage was 8 kV, the gas flow rate was 0.9 m³/h and the relative humidity was 65%, the degradation efficiency and mineralization rate of o-chlorotoluene were increased by 33.9% and 13.1%, respectively, compared with that of DBD system alone. The concentration of O3 and NO2 decreased by 48.2 mg/m³ and 12.3 mg/m³ respectively, and the CO2 selectivity increased by 12%. [ABSTRACT FROM AUTHOR]

A potential anode material for lithium‐ion batteries (LIBs), Co3O4 has been widely considered by many scholars because of its excellent properties in terms of electrochemical characteristics and theoretical specific capacity. However, according to the existing research results, we found that the improvement of the electrochemical performance of Co3O4 has encountered a bottleneck because its intrinsic conductivity is not high enough, and more importantly, the volume expansion is too significant during the charge and discharge process, which leads to the material structure breaking. Therefore, this paper proposes a simple and scalable solvothermal and subsequent calcination method to prepare Co3O4 and reduced graphene oxide (RGO) composite nanoparticles with superior microstructures, and their morphological and electrochemical properties were investigated at different calcination temperatures. As a high‐performance anode material for lithium‐ion batteries, the Co3O4/RGO nanoparticles obtained at 550 °C exhibited terrific initial discharge capacity of 1714.2 mAh g−1, the reversible specific capacity of 1191.9 mAh g−1 with quality coulombic efficiency 98.17 % at 0.5 A g−1 after 100 cycles and extraordinary rate performance (907.6 mAh g−1 with a coulombic efficiency of 99.2 % at 2 A g−1). The facile synthesis method and excellent findings have led to better application prospects for Co3O4/RGO nanoparticles. [ABSTRACT FROM AUTHOR]

Developing cathode materials with high performance in oxygen reduction reaction (ORR) is desirable for proton ceramic fuel cells (PCFCs) for energy conversion technology. BaCo0.4Fe0.4Zr0.1Y0.1O3–δ (BCFZY) is widely investigated as a cathode. Herein, BCFZY cathode is used as a paradigmatic example to study the impact of calcination temperature on microstructure, electronic structure, and ORR performance. Ion beam‐scanning electron microscopy indicates BCFZY prepared at 800 °C (BCFZY800) exhibits the largest specific surface area and cathode/electrolyte contact area. BCFZY800 exhibits a peak power density of 1.32 W cm−2 at 650 °C, which is 37% and 193% higher than that of BCFZY prepared at 700 °C (BCFZY700) and 1100 °C (BCFZY1100), respectively. Furthermore, BCFZY800 demonstrates high long‐term stability over 500 h. Soft X‐Ray absorption spectra indicate that the oxidation state of BCFZY800 is reduced, suggesting more catalytically active sites than those of BCFZY700 and BCFZY1100 after the ORR. This work provides a new understanding for enhanced PCFCs performance by proper porosity structure via fine‐tuning the calcination temperature. [ABSTRACT FROM AUTHOR]

Global efforts to minimise carbon dioxide emissions are also leading to attempts to use calcined clays (CC) as a partial substitute for cement in concrete. While the hydration mechanism of such CC blended cements is now well understood, the range of effective admixtures like polycarboxylate ethers (PCE) is limited. There are PCE types that promise relatively high effectiveness, but the mechanisms of action are not yet sufficiently understood. For a detailed understanding of the adsorption of such PCEs, spatially resolved studies of the binder were performed using a combination of fluorescence and scanning electron microscopy. In a comparison of two superplasticisers, the investigations have shown different sites of preferred adsorption in a CC blended system and the results can be correlated with flow tests and setting behaviour. The investigations have shown that a certain PCE type has a higher adsorption on CC and other components of a blended system in comparison to other types. LAY DESCRIPTION: Efforts to reduce carbon dioxide emissions globally are driving attempts to use calcined clays as a partial replacement for cement in concrete. Although the hardening mechanism of cements blended with calcined clays is well understood, the range of effective admixtures, such as plastisicing agents, is limited. While some plastisicing agent types show relatively high effectiveness, their mechanisms of action are not yet fully understood. To understand how these plastisicing agents interact with the compounds, fluorescence and scanning electron microscopy has been used to study this interaction. Two different plastisicing agent types have been compared and it was found that they prefer different sites of the compounds to interact with in a blended cement. These results can be correlated with flow tests and setting behaviour. The investigations have shown that one particular type of plastisicing agents has a higher affinity to calcined clay and other components of a blended system compared to other types. [ABSTRACT FROM AUTHOR]

Recently, CaO‐doped (≤4 mol.%) tetragonal zirconia (CaSZ) ceramic was recommended as a potential alternative to yttria‐stabilized ZrO2 (YSZ). Here, we investigate the limits of starting particle sizes on the stability of tetragonal (t) phase and other associated benefits on measured properties. Synthesized CaSZ powders calcined with different temperatures were used as a mono‐sized or mixed (i.e., two different calcination temperatures) batch fraction for making dense CaSZ ceramic. The mixed‐batch powders were found to be far more efficient in stabilizing the t‐phase in ceramic. Compared to YSZ, CaSZ recorded remarkable enhancement in toughness (up to 8.3 MPa m$\sqrt {\mathrm{m}} $). Contrary to YSZ, CaSZ ceramic demonstrated outstanding thermal stability. [ABSTRACT FROM AUTHOR]

[Display omitted] • A new 3-D bi-metal organic framework was synthesized by hydrothermal method. • After pyrolysis, binary metal oxides were prepared and applied to the anode materials of LIBs. • CeCo-700 has the highest specific capacity of 952 mAh g−1 at 100 mA g−1 after 150 cycles. Precursor method is a well-known technology for preparing certain functional materials. In this work, a novel 3d-4f bimetallic organic framework, denoted as 45MCeCo (45 M representing 4,5-imidazole dicarboxylic acid), was successfully synthesized via a hydrothermal technique. The compound thus obtained has the molecular formula of C 10 H 11 CeCoN 4 O 12. By meticulously controlling the amounts of the experimental materials, it was feasible to prepare flower-like crystals possessing identical single crystal structures and significantly larger specific surface areas. As a precursor for electrode materials, this structure underwent calcination at different temperatures to prepare Co 3 O 4 /CeO 2 composites with in situ composite heterostructures. Post-electrochemical tests revealed that CeO 2 remains unreactive across all potentials, thereby contributing to the stabilization of the electrode material structure. In contrast, Co 3 O 4 participated in redox reactions to provide a specific capacity to the sample. In addition, when comparing the performance of the electrode material under different calcination conditions, it became evident that the material exhibited optimal electrochemical performance when subjected to a temperature of 700 °C for 2 h. [ABSTRACT FROM AUTHOR]

Cerium oxide (CeO2) was synthesized using the precipitation method at various calcination temperatures ranging from 500 to 700°C. Cerium(III) nitrate hexahydrate (Ce(NO)3.6H2O) was used as the precursor for cerium, while Cetyltrimethylammonium bromide (CTAB) acted as the morphology-directing agent. Characterization results indicated that pure CeO2 was obtained at all calcination temperature variations. Calcination temperature influences crystallinity, crystal size, and CeO2 crystal parameters. The crystallinity and crystal size of CeO2 increased with the rising calcination temperature, reaching values of 81.1-84.5% and 15.58-23.12 nm, respectively, along with larger crystal parameters as the temperature increased (a = 5.406-5.410 Å). Surface morphology showed irregular shapes of CeO2 particles, with decreasing sizes as the calcination temperature increased, ranging from 0.2-5.6 μm at 600°C to 0.12-2.9 μm at 700°C. The Ce/O ratio on the surface increased with the rising calcination temperature, reaching a range of 0.48-0.57. CeO2 obtained from calcination at 600°C exhibited the highest fluorescence emission intensity (λ= 496 nm), indicating the least oxygen vacancies presence. Therefore, for antioxidant and catalyst applications, it is preferable to calcinate CeO2 at 700°C. [ABSTRACT FROM AUTHOR]

The problem of electromagnetic pollution is becoming more and more serious with the coming of the 5G era. The development of high-performance electromagnetic absorbing materials is an effective way to solve that problem. In this study, disposable gauze masks are used as raw materials to prepare Ni particles/carbon composites by impregnation process and subsequent calcination for microwave absorption application. Ni particle/carbon composites consist mainly of lamellar carbon and Ni particles. Ni particles in Ni particles/carbon composites are surrounded by graphite phase to form Ni/C core–shell structure. The strong RL of − 42.8 dB at 1.5 mm thick and an effective absorption bandwidth of 3.63 GHz are obtained from Ni particle/carbon composites calcined at 850 °C. This work provides a new idea for the application of disposable gauze masks. [ABSTRACT FROM AUTHOR]

The utilization of calcined coal gangue (CCG) and limestone for the preparation of blended cement is an efficient approach to address the issue of coal gangue disposal. However, the compressive strength development of blended cement is slow, particularly at high substitution levels of CCG. Therefore, this study aimed to promote the hydration and mechanical properties of the calcined coal gangue–limestone blended cements by increasing the curing temperature. In this study, the samples were cured at two different temperatures, namely 20 and 40 °C. The four groups of samples contained 15 wt.%, 30 wt.%, 45 wt.% and 60 wt.% cement substitutions using CCG and limestone (2:1 mass ratio). The compressive strength, hydration and microstructure were investigated at the ages of 1 to 28 d. X-ray diffraction (XRD) and thermogravimetry (TG) were used to study the hydration behavior of samples. Mercury intrusion porosimetry (MIP) and scanning electron microscopy (SEM) were used to determine the microstructure of the samples. The results indicate that an increase in curing temperature significantly promotes the compressive strength of the calcined coal gangue–limestone blended cements from 1 to 28 d. The microstructural analysis indicates that increasing the curing temperature not only promotes cement hydration but also facilitates the reaction of CCG, which precipitated more hydrates such as C-A-S-H gel, Hc and Mc. These hydrates are conducive to refining the pore structures and densifying the microstructure, which sufficiently explains the enhanced compressive strength of the calcined coal gangue–limestone blended cements. [ABSTRACT FROM AUTHOR]

In this work, the effects of calcination temperatures ranging from 600°C to 1,000°C on the changes in mineralogical phases and mechanical characteristics of calcined impure kaolinite clay blended cement mortars were investigated. The impact of calcining temperature on pozzolanic activity of impure kaolinite clay was evaluated using direct and indirect methods. The findings demonstrated that at 700°C, kaolinite changed from a crystalline to an amorphous metakaolin phase. Specific surface, water demand, and setting time of the blended cements decreased as calcining temperature increased. The compressive strengths of blended cement mortar containing low-grade clay calcined at 700°C, 800°C, and 900°C were found to be greater than that of 600°C and 1,000°C. Based on the results of pozzolanic reactivity evaluations and compressive strength development, the most effective calcining temperature was shown to be between 800°C and 900°C. [ABSTRACT FROM AUTHOR]

As a successor to LiFePO4, the research interest in LiMn1−yFeyPO4 has been sustained due to its higher working voltage and safety features. However, its further application is limited by the low compaction density caused by uncontrolled particle size. In this study, the high-quality LiMn0.69Co0.01Fe0.3PO4 (LMFP) materials were prepared using the freeze-drying method to process the LMFP precursor synthesized through a solvothermal crystallization method followed by a calcination process at different temperatures (400–550 °C). The results demonstrate that the obtained particles exhibit a spheroidal shape with a low specific surface area after secondary crystallization calcination at 700 °C. The compaction density increased from 1.96 g/cm3 for LMFP precursor (LMFP-M1) to 2.18, 2.27, 2.34, and 2.43 g/cm3 for samples calcined at 400, 450, 500 and 550 °C, respectively, achieving a maximum increase of 24%. The full cell constructed with the high-compaction-density material calcined at 500 °C displayed discharge capacities of 144.1, 143.8, and 142.6 mAh/g at 0.5, 1, and 3 C rates, respectively, with a retention rate of 99% at 3 C rate. After undergoing charging and discharging cycles at a rate of 1 C for up to 800 cycles, the capacity retention rate was found to be 90%, indicating an expected full cell life span exceeding 2500 cycles. [ABSTRACT FROM AUTHOR]

To improve the hot properties of magnesia-zirconia materials, magnesia-zirconia sand was pre-synthesized with Xiuyan second grade magnesite and desilicated zirconia, and then magnesia-zirconia materials were prepared using the pre-synthesized magnesia-zirconia sand and fused magnesia, mixing, molding, drying and calcining. The effects of the pre-synthesized magnesia-zirconia sand addition (10%, 20% and 30%, by mass) and calcination temperature (1 500, 1 600 and 1 700 °C) on the bulk density, apparent porosity, linear shrinkage rate on heating, cold modulus of rupture, thermal shock resistance and slag resistance of the materials were investigated. The phase composition and microstructure were also analyzed. The results show as follows: (1) as the pre-synthesized magnesia-zirconia sand addition and calcination temperature increase, the bulk density and cold modulus of rupture increase, while the apparent porosity decreases; (2) the linear shrinkage rate decreases with the increasing pre-synthesized magnesia-zirconia sand addition and increases with the increasing calcination temperature; (3) when the pre-synthesized magnesia-zirconia sand addition is 20% and the calcination temperature is 1 600 °C, the sample performs the best thermal shock resistance, which is improved due to microcrack toughening induced by the pre-synthesized magnesia-zirconia sand; (4) when the pre-synthesized magnesia-zirconia sand addition is 20% and the calcination temperature is 1 700 °C, the sample shows the optimal slag resistance, which is mainly due to the fact that ZrO2 reacts with the slag to generate CaZrO3 and spinel, preventing the further corrosion and penetration of the steel slag. [ABSTRACT FROM AUTHOR]

CeO2 is an outstanding support commonly used for the CuO-based CO oxidation catalysts due to its excellent redox property and oxygen storage–release property. However, the inherently small specific surface area of CeO2 support restricts the further enhancement of its catalytic performance. In this work, the novel mesoporous CeO2 nanosphere with a large specific surface area (~190.4 m2/g) was facilely synthesized by the improved hydrothermal method. The large specific surface area of mesoporous CeO2 nanosphere could be successfully maintained even at high temperatures up to 500 °C, exhibiting excellent thermal stability. Then, a series of CuO-based CO oxidation catalysts were prepared with the mesoporous CeO2 nanosphere as the support. The large surface area of the mesoporous CeO2 nanosphere support could greatly promote the dispersion of CuO active sites. The effects of the CuO loading amount, the calcination temperature, mesostructure, and redox property on the performances of CO oxidation were systematically investigated. It was found that high Cu+ concentration and lattice oxygen content in mesoporous CuO/CeO2 nanosphere catalysts greatly contributed to enhancing the performances of CO oxidation. Therefore, the present mesoporous CeO2 nanosphere with its large specific surface area was considered a promising support for advanced CO oxidation and even other industrial catalysts. [ABSTRACT FROM AUTHOR]

Nickel chloride (NiCl2) is a typical hexagonal layered semiconductor material with wide application. However, it is mainly restricted by complicated technological process within ultrahigh dehydration temperature. Utilizing copper doping, a sort of high purity and remarkable crystallinity NiCl2 is fabricated using a simple low‐temperature calcination technique. The dehydration temperature is decreased from 600 to 400 °C because the adsorbed copper ions on NiCl2 dihydrate surface can weaken NiO bond strength. Serving for thermal battery cathode, copper‐doped NiCl2 exhibits remarkable discharge ability at 500 mA cm−2, equipped with supernormal power density of 16.27 kW kg−1 and energy density of 717 Wh kg−1 simultaneously. Its energy density is increased by 28% compared to NiCl2. Copper doping optimizes thermodynamics process of discharge reaction and modifies local electronic structure of NiCl2. For copper‐doped NiCl2, the shift of Ni 3d and Cl 3p to lower energy level results in elevated redox potential, and the reduction of bandgap accelerates the carrier mobility, further promoting discharge degree. Utilizing metal ions dopant, this research surmounts the low‐temperature synthesis of NiCl2 and addresses its inferior electrochemical performance, ensuring high energy‐power output. This will expand the application scenarios of NiCl2‐based cathode materials. [ABSTRACT FROM AUTHOR]

Calcination temperature is a crucial parameter that can be easily controlled to induce a change in material properties. Herein, iron tungstate (FeWO4) was synthesized via a hydrothermal method using iron(II) sulfate heptahydrate and sodium tungstate dihydrate as precursors and calcined at the temperature between 300 oC and 700 oC. With increasing calcination temperature, the saturation magnetization of FeWO4 nanoparticles decreased from 6.6 emu/g for FeWO4 to 0.4 emu/g for FeWO4_700, whereas their band gaps increased from 1.95 eV for FeWO4 to 2.20 eV for FeWO4_700. More crystallinity and crystal defects, and morphological changes at higher calcination temperatures contributed to varying magneto-optical properties of FeWO4 nanoparticles. [ABSTRACT FROM AUTHOR]

Pyrite exhibits considerable potential as an adsorbent in wastewater treatment. However, few pyrite adsorbents are directly obtained from natural pyrite, as most are composite materials that require a complex preparation process. To develop a pyrite-based adsorbent with a simple preparation process, pyrite was processed by calcination at 400, 600, and 800 °C for 4 h and ball-milled into a fine powder. The adsorption properties of the pyrite powder were systematically explored. The calcined pyrite powder was characterized by SEM-EDS and XRD. The results revealed that the pyrite calcined at 600 °C exhibited excellent adsorption properties and was primarily composed of Fe7S8. The optimum conditions for Cr(VI) removal were a temperature of 45 °C, an adsorbent dosage of 1 g, an equilibration time of 60 min, and an initial pH of 3. Moreover, the calcined pyrite powder exhibited excellent reusability, and the Cr(VI) removal rate exceeded 65% after three cycles. The Cr(VI) adsorption on pyrite can be well described by the Freundlich model and pseudo-second-order kinetic equation. The calcination temperature is the main factor affecting the adsorption performance of pyrite. Therefore, the calcined pyrite powder is expected to be an excellent adsorbent for Cr(VI) in the wastewater treatment industry. Pyrite has shown promising development prospects in the field of wastewater purification. However, the preparation of most pyrite-based adsorbents is complicated. Upon high-temperature calcination, pyrite is used in traditional Chinese medicine clinics to promote the healing of fractures. The efficiency and underlying mechanism of Cr(VI) adsorption from water using calcined pyrite was investigated. The adsorbent was prepared using a simple method and exhibited excellent adsorption performance, thus allowing its application in preparing ore-based adsorbents for water pollution treatment. [ABSTRACT FROM AUTHOR]

Defect‐engineering is a viable strategy to improve the activity of nanocatalysts for the oxygen evolution reaction (OER), whose slow kinetics still strongly limits the broad market penetration of electrochemical water splitting as a sustainable technology for large‐scale hydrogen production. High‐entropy spinel oxides (HESOs) are in focus due to their great potential as low‐cost OER electrocatalysts. In this work, electrospun HESO nanofibers (NFs), based on (Cr,Mn,Fe,Co,Ni), (Cr,Mn,Fe,Co,Zn) and (Cr,Mn,Fe,Ni,Zn) combinations, with granular architecture and oxygen‐deficient surface are produced by calcination at low temperature (600 or 500 °C), characterized by a combination of benchtop analytical techniques and evaluated as electrocatalysts for OER in alkaline medium. The variation of HESO composition and calcination temperature produces complex and interdependent changes in the morphology of the fibers, crystallinity and inversion degree of the spinel oxide, concentration of the oxygen‐vacancies, cation distribution in the lattice, which mirror on different electrochemical properties of the fibers. The best electrocatalytic performance (overpotential and Tafel slope at 10 mA cm−2: 360 mV and 41 mV dec−1, respectively) pertains to (Cr1/5Mn1/5Fe1/5Co1/5Ni1/5)3O4 NFs calcined at 500 °C and results from the lower outer 3d‐electron number, eg filling closer to its optimal value and higher occupation of 16d sites by the most redox‐active species. [ABSTRACT FROM AUTHOR]

In this study, the impact of varying calcination temperatures on the structural, impedance spectroscopy, and optical properties of Ni0.4Cd0.3Co0.3Fe2O4 spinel ferrites was examined. The experimental XRD results indicated that increasing the calcination temperature resulted in an increase in both grain size and cell parameters. The samples display direct optical transitions based on the Tauc method. With increasing grain size, band-gap energy (Eg) and activation energy (Ea) decrease. Increased calcination temperature also reduces Urbach energy (Eu) due to the decrease in defects and disorder in the samples. Besides, optical dielectric constants, conductivity, penetration depth, loss factor, refractive index and extinction coefficient are also studied. The Nyquist diagram modeling revealed that the conduction mechanism in the samples is influenced by both grain and grain-boundary contributions. To explain the conduction process, the Overlapping-Large Polaron Tunneling model (OLPT) was employed. Additionally, the materials exhibited high electrical resistivity and low dielectric constants and losses at higher frequencies. These properties make the Ni0.4Cd0.3Co0.3Fe2O4 samples well-suited for applications involving high-frequency and microwave absorption. [ABSTRACT FROM AUTHOR]