Optimum Calcination Temperature Research Articles

Effect of Calcination Temperature on the Structural and Electrochemical Properties of NMC Cathodes for Lithium-Ion Batteries

The electrochemical and thermal properties of Li[NixMnyCoz]O2 are strongly dependent on its composition and structural characteristics [1]. Among many options available there is no observed middle ground since each of the component cations has a different, specific function in the cathode material [2]. Developing an ideal cathode material with both high capacity and safety is a challenging task that requires precise control of microstructure and physicochemical properties of the electrode [3]. Firstly, the most promising amendment is the increase of nickel content as it enhances the specific discharge capacity, although the gradual safety characteristics decrease over cycling [4]. The optimum composition of NMC has not yet been found, thus, research aiming at improving its properties is still ongoing. The aim of this study is to analyze the impact of calcination temperature on the structural, morphological, and electrochemical properties of lithium nickel-manganese-cobalt oxides. The research focuses on optimization of the last step of the synthesis process. The results will be further used for the gradient structure material design based on nickel-rich core, since in that case the calcination step seems to be crucial for final material properties.Materials were prepared by coprecipitation method of the complex metal hydroxide precursor NixMnyCoz(OH)2, subsequently mixed with lithium hydroxide and annealed at different temperatures in air to obtain the lithiated powders. Constant monitoring of the conditions, such as synthesis temperature, solution pH, stirring frequency and calcination temperature, enable to control the particle morphology, which has a significant impact on lithium cations migration capability, and performance characteristics of the assembled Li-ion cells. To control the optimization process and furtherly investigate the material structure we used various methods. All NMC samples were analyzed using in-situ temperature dependent XRD, followed by the SEM and chronopotentiometry investigation. As the thermal and electrochemical stabilities are related to the structural stability, the various synthesized NMC materials were subjected to variable temperature measurements of X-ray diffraction (VT-XRD). The nickel-rich NMC are supposed to be calcinated in lower temperatures than its nickel-poor NMC analogs. The VT-XRD makes it possible to presume one optimal calcination temperature for both: nickel-poor and nickel-rich phases within the gradient NMC structure. X-ray powder diffraction was used to characterize the crystal structure of the prepared materials, giving general information about the phases present and their crystallographic parameters. Furthermore, scanning electron microscopy (SEM) was used to explore the morphologies of the prepared powders, both before, and after calcination at different temperatures. Understanding the influence of grain and particle as well as grain boundaries characteristics on overall material properties is also crucial, as small primary particle sizes with high surface areas contribute essentially to discharge capacities. To validate the formed hypothesis electrochemical tests have been conducted. Chronopotentiometry allowed for determination of battery cycling parameters, such as specific discharge capacity and cyclability. The combination of these three methods helps to identify the material characteristics and shows a direction for further material development.A detailed analysis will be presented during the conference. This work was funded by the National Science Center in Poland through the Sonata 17 programme (No. UMO-2021/43/D/ST5/03094).Reference: Amalia Christina Wagner et al. Hierarchical Structuring of NMC111-Cathode Materials in Lithium-Ion Batteries. ACS Applied Energy Materials 2020 3 (12), 12565-12574.Thomas Entwistle et al. Co-precipitation synthesis of nickel-rich cathodes for Li-ion batteries, Energy Reports, Volume 8, Supplement 11, 2022, Pages 67-73, 2352-4847.Dong Ren, et al. Systematic Optimization of Battery Materials. ACS Applied Materials & Interfaces 2017 9 (41), 35811-35819. Hyung-Joo Noh et al. , Comparison of the structural and electrochemical properties of layered Li[NixCoyMnz]O2 cathode material for lithium-ion batteries, Journal of Power Sources, Volume 233, 2013, Pages 121-130, 0378-7753.

Reactivity of kaolinitic clays calcined in the 650 °C–1050 °C temperature range: Towards a robust assessment of overcalcination

Using calcined clays as supplementary cementitious materials is one of the main solutions available for a substantial and widespread reduction of the clinker factor in cement. Thus, understanding the phenomena governing their production process and reactivity is crucial for a successful technological deployment. In this study, the mineralogical and physical changes experienced by kaolinitic clays calcined within 650 and 1050 °C were explored, with emphasis on the identification of overcalcination. It was observed that the decrease in reactivity above the optimum calcination temperature is associated with the formation of Al–Si spinel and a decrease in specific surface area, which is linked to a modification of the pore size distribution within the particles. Differential scanning calorimetry (DSC) was identified as the most robust, and repeatable technique to identify an overcalcined kaolinitic clay. In combination with thermogravimetric analysis (TGA), it can provide a complete calcination process overview, relevant for quality control purposes.

Regulating afterglow of LiGa5O8:Cr3+ for dynamic anti-counterfeiting

Fluorescent materials are widely used in the field of anti-counterfeiting. However, conventional fluorescent materials are limited in anti-counterfeiting applications due to their static mode. Here, LiGa5O8:Cr3+ phosphors were prepared at different calcination temperatures by high-temperature solid-state reaction and further fabricated into dynamic anti-counterfeiting films. Samples can emit red light with main emission peak at 719 nm due to 2E → 4A2 transition of Cr3+ ions. By adjusting calcination temperature from 1300 °C to 1550 °C, red afterglow of the film was controlled with respect to luminescence intensity and duration. In addition, 1450 °C was identified as the optimum calcination temperature to prepare LiGa5O8:Cr3+ phosphors with the best luminescent performance. Based on this control strategy, the application of LiGa5O8:Cr3+ in the field of dynamic anti-counterfeiting can be realized.

Effect of Calcination Temperature on the Powder of Freshwater Snail Shells (Sulcospira testudinaria) Properties

Gastropod shells, such as those from the freshwater snail (Sulcospira testudinaria), have garnered interest as potential sources of calcium precursors. These shells are rich in calcium carbonate (CaCO3), which can be thermally decomposed into calcium oxide (CaO) through calcination. However, more information is needed on optimizing calcium extraction from the Sulcospira testudinaria (SST) shells. This study aims to investigate the influence of calcination temperature on the characteristics of powder of these shells. The study involves two sample treatments: uncalcined shells and shells calcined at temperatures ranging from 500°C to 1100°C for 1 hour. Fourier transform infrared spectroscopy (FTIR) analysis of uncalcined shell powder revealed the presence of aragonite functional groups within the CaCO3 structure. X-ray diffraction (XRD) analysis provided insights into the transformation of crystalline phases of CaCO3, starting from aragonite to calcite and eventually to calcium oxide, explaining the material's weight loss during calcination. The conversion of aragonite to calcite occurs between 500°C and 700°C, while optimal decomposition into CaO is achieved at 1000°C. X-ray fluorescence (XRF) analysis indicated reduced impurities in the samples post-calcination. Scanning electron microscopy (SEM) detailed the morphological characteristics of the shell powders, highlighting temperature-dependent surface features. In conclusion, the optimal calcination temperature for extracting calcium from SST shells is 1000°C. The resulting calcium oxide can be a valuable precursor for various material applications. This research contributes to the efficient utilization of biowaste resources, emphasizing the potential of freshwater snail shells in the sustainable production of calcium-derived materials.

Characterization of net-zero pozzolanic potential of thermally-derived metakaolin samples for sustainable carbon neutrality construction

Metakaolin (MK) is one of the most sustainable cementitious construction materials, which is derived through a direct heating procedure known as calcination. Calcination process takes place substantially lower temperatures than that required for Portland cement, making it a more environmentally sustainable alternative to traditional cement. This procedure causes the removal of hydroxyl water from the naturally occurring kaolin clay (Al2Si2O5(OH)4 with MK (Al2O3·2SiO2) as its product. Kaolin naturally exists in large amount within 5°29′N–5°35′N and 7°21′E–7°3′E geographical coordinates surrounding Umuoke, Obowo, Nigeria. Alumina and silica are the predominant compounds in MK, which provide it with the pozzolanic ability, known as the 3-chemical pozzolanic potential (3CPP), with high potential as a cementitious material in concrete production and soil stabilization. Over the years, researchers have suggested the best temperature at which MK is derived to have the highest pozzolanic ability. Prominent among these temperature suggestions were 800 °C (3CPP of 94.45%) and 750 °C (3CPP of 94.76%) for 2 h and 5 h’ calcination periods, respectively. In this research paper, 11 different specimens of Kaolin clay obtained from Umuoke, Nigeria, were subjected to a calcination process at oven temperatures from 350 to 850 °C in an increment of 50 °C for 1 h each to derive 11 samples of MK. The MK samples and Kaolin were further subjected to X-ray fluorescence), scanning electron microscopy (SEM) and X-ray diffraction (XRD) Brunauer–Emmett–Teller (BET) tests to determine the microstructural behaviour and the pozzolanic properties via the 3CPP as to exploit the best MK with the highest cementing potential as a construction material. The results show that the MK heated at 550 °C and 800 °C produced the highest pozzolanic potentials of 96.26% and 96.28%, respectively. The enhancement in pozzolanic potential at optimum calcination temperature is attributed to an increase in the specific surface area upon calcination of kaolinite confirmed by BET results. The SEM and XRD results further supported the above result with the strengthened crystal structure of the MK at these preferred temperatures. Generally, 550 °C is more preferred due to the less heat energy needed for its formulation during 1 h of calcination, which outperforms the previous results, that suggested 750 °C and 800 °C in addition to longer hours of heat exposure.

Substitution of cement by marine clay in spray-based 3D concrete printing

Spray-based 3D concrete printing (S-3DCP) is a type of 3D concrete printing specifically for automated constructions on vertical and overhanging surfaces, e.g. facades and ceilings. In this study, cement is partially substituted by calcined marine clay to develop a high-performance mixture for S-3DCP. Through setting, rheological, and tack tests, the fresh properties of the mixtures with marine clays calcined after different temperatures have been assessed. Considering pumping and deposition performance, tackiness, and sustainability, the optimum calcination temperature of marine clay is determined as 700 °C. The subsequent spray-based printing test shows that compared with the mixture without marine clay, the mixture with the marine clay calcined at 700 °C has a more uniform thickness distribution and 185% higher building capacity. The study contributes to the deeper understanding of the rheological and tack properties of the mixtures with calcined marine clay, which guides the future utilization of marine clay.

Porous scaffold hydroxyapatite from sand lobster shells (Panulirus homarus) using polyethylene oxide/chitosan as polymeric porogen for bone tissue engineering.

The hydroxyapatite (HAp; Ca10 (PO4 )6 (OH)2 )) has good biocompatibility, bioactivity, and osteoconductivity as a bone implant because the main inorganic mineral of human bone is HAp. The use of scaffold HAp from biogenic resources that contain high calcium and polymer as a pore forming agent to support bone growth is a longstanding area of interest. In this study, porous scaffolds based on HAp were synthesized from sand lobster (SL; Panulirus homarus) shells as a source of calcium using the porogen leaching method with polyethylene oxide (PEO) and chitosan (Chs) as polymeric porogen. The present study aims to synthesize HAp derived from SL shells and evaluate the effect variations of PEO on the physicochemical properties of the scaffold and cytotoxicity in cell viability assay. Briefly, the SL shell powder was calcinated with temperature variations of 600°C, 800°C, and 1000°C for 6 h. Based on the characterization, it was shown that 1000°C was the optimum calcination temperature for SL shells to synthesize HAp using the precipitation method. The characterization results of HAp using energy dispersive x-ray (EDX) revealed that the molar ratio of Ca/P was 1.67. The Fourier transform infrared (FTIR) and x-ray diffractometer (XRD)spectral patterns indicated that HAp had been successfully synthesized with minor β-tricalcium phosphate (β-TCP), a calcium phosphate with high biocompatibility. Porous scaffolds were synthesized by varying the concentration of PEO at 0, 5, 10, and 15 wt %. Physicochemical analysis revealed that a higher concentration of PEO affected decreased crystallinity and compressive strength, but on the other hand, the porosity and pore sizes increased. Based on the physicochemical analysis, the synthesized porous scaffold showed that HAp/PEO/Chs 15 wt % had the most potential as a scaffold for biomedical applications. MTT Assay, after 24 h incubation, revealed that the scaffold was safe for use at low concentrations on the MC3T3E1 osteoblast cells, with a percentage of cell viability of 83.23 ± 3.18% at 23.4375 μg/mL. Although the cell viability decreased at higher concentrations, the HAp/PEO/Chs 15 wt % scaffold was cytocompatible with the cells. Thus, in the present study, HAp/PEO/Chs 15 wt % was the best scaffold based on pore structure, chemical composition, mechanical and crystalographic properties and cell viability.

Visible-Light-Driven Photocatalytic Degradation of High-Concentration Ammonia Nitrogen Wastewater by Magnetic Ferrite Nanosphere Photocatalysts

In this study, magnetic CuFe2O4, MgFe2O4, and ZnFe2O4 nanosphere photocatalysts were prepared by the sol–gel method at 300 °C, 400 °C, and 500 °C, respectively (named as CF300, CF400, CF500, MF300, MF400, MF500, ZF300, ZF400, and ZF500). The characterization by X-ray diffraction (XRD) revealed that the optimal calcination temperature was 400 °C. Then, CF400, MF400, and ZF400 were used to treat high-concentration ammonia nitrogen wastewater (HCAW, 1000 mg/L) at different pH levels. The result showed that the optimal pH for CF400, MF400 and ZF400 to degrade HCAW was 9.0, and CF400 required a shorter illumination time (80 min) than MF400 and ZF400 (120 min) to completely remove ammonia nitrogen from HCAW. However, CF400 was unstable and decomposed, and a blue substance was observed during the magnetic recovery experiment. The recovery rate of ZF400 (66.7%) was higher than MF400 (53.2%) with no decomposition phenomenon, and the ammonia nitrogen removal rate of ZF400 remained above 90% after five cycles. Additionally, the ammonia nitrogen removal rate of ZF400 could reach 80.2% when the ammonia nitrogen concentration was as high as 5000 mg/L. Therefore, compared with CF400 and MF400, ZF400 was more suitable for treating HCAW.

Enhanced photodegradation of CuCo2O4 nanoflower for the dye degradation of Rhodamine B and Methyl Violet

The investigation examined into the effect of different hydrothermal reaction temperatures and durations on the formation of nanoflower-shaped CuCo2O4 nanostructures (CCO NPs). The structural, morphological, functional, optical, and magnetic properties of the synthesized CCO NPs were thoroughly examined. The optimal calcination temperature was determined using Thermogravimetric and Differential Thermal Analysis (TG/DTA), which identified 400 °C as the ideal temperature. Following X-ray Diffraction (XRD) analysis, pure CuCo2O4 samples were formed, with calculated average crystallite sizes of 27 nm for CCO-A, 48 nm for CCO-B, 30 nm for CCO-C, and 31 nm for CCO-D samples. Fourier Transform Infrared (FTIR) analysis provided additional confirmation of pure CuCo2O4 formation, with characteristic bands in the 665–662 cm-1 and 583–567 cm-1 ranges indicating the presence of CuO and CoO bonds. SEM, High-Resolution SEM (HRSEM) and High-Resolution Transmission Electron Microscopy (HRTEM) all supported the observation of a distinct flower-like structural morphology. The optical properties of an optimized sample were revealed by UV–Visible Diffuse Reflectance Spectroscopy (UV-DRS) analysis, which revealed a band gap of 3.3 eV. According to Vibrating Sample Magnetometer (VSM) results, the magnetic behavior of CCO-D nanostructures at room temperature exhibited paramagnetic characteristics. The saturation magnetization (Ms), remanent magnetization (Mr) and coercivity (Hc) values were determined to be 0.26218 emu/g, 2.7214 × 10–3 emu/g and 29.787 Oe, respectively. To evaluate photocatalytic performance, the CCO-D photocatalyst was used to degrade Methyl Violet and Rhodamine B dyes. CCO-D degraded MV dye with greater efficiency (93%) than RhB (85%) when exposed to sunlight. These findings highlight CCO-D's potential as a photocatalyst for the degradation of organic dyes.

Improving the electrochemical properties of Ti3C2Tx MXene for H2S electrochemical sensor by calcination

The existence level and metabolic mechanism of hydrogen sulfide (H2S) have been proved to have an important impact on organisms, even affecting the generation and development of many neurological diseases. Therefore, it is essential to develop sensitive and accurate H2S sensors to detect H2S concentration at trace level and provide effective research tools for studying the mechanism of action of H2S on organisms. MXene is a class of two-dimensional transition metal carbonitrides with a graphene-like structure, which indicating great application prospects as a biosensor due to its large specific surface area and good conductivity. In this work, the properties of multilayer Ti3C2Tx MXene materials are optimized concerning their physical structure and functional groups. Based on the Li + intercalation method, SL-Ti3C2Tx MXene is prepared by a mild route, and its electrochemical performance is optimized by high temperature calcination under high purity argon conditions. The change in material properties at high temperature is discussed through structural and chemical analysis, and the optimal calcination temperature is determined to be 700 °C. The constructed H2S electrochemical sensor exhibits high stability and reproducibility in applications, with a detection range of 0.1–500 μM, and the detection limit is reduced to 5.77 nM.

Effect of Calcination Temperature on Prepared Γ-Al2O3 as Support Catalyst

The effect of calcination temperature on the surface properties of gamma alumina was investigated in this study, which is used as a support for multiple metal-loaded catalysts. The Sol-gel technique was used to create -Al2O3 support from aluminum nitrate as a precursor at various calcination temperatures (500, 550, 600, and 650°C). Then, for each sample, characterization tests such as X-Ray fluorescence (XRF), X-Ray diffraction (XRD), Thermal gravimetric analysis (TGA), and surface area (BET) are performed to determine the optimal calcination temperature to produce highly active composite catalyst support. It has been discovered that samples calcined at 600 and 650°C have very similar properties in terms of mechanical strength, thermal stability, crystallinity, high purity, and surface properties or morphology. However, the surface area and pore volume of 600°C are thought to be superior to those of 650°C.

Scalable Synthesis of Oxygen Vacancy-Rich Unsupported Iron Oxide for Efficient Thermocatalytic Conversion of Methane to Hydrogen and Carbon Nanomaterials.

Thermocatalytic methane decomposition (TCMD) involving metal oxides is a more environmentally friendly and cost-effective strategy for scalable hydrogen fuel production compared to traditional methane steam reforming (MSR), as it requires less energy and produces fewer CO/CO2 emissions. However, the unsupported metal oxide catalysts (such as α-Fe2O3) that would be suited for this purpose exhibit poor performance in TCMD. To overcome this issue, a novel strategy was developed as a part of this work, whereby oxygen vacancies (OVs) were introduced into unsupported α-Fe2O3 nanoparticles (NPs). Systematic characterization of the obtained materials through analytical techniques demonstrated that mesoporous nanostructured unsupported α-Fe2O3 with abundant oxygen vacancies (OV-rich α-Fe2O3 NPs) could be obtained by direct thermal decomposition of ferric nitrate at different calcination temperatures (500, 700, 900, and 1100 °C) under ambient conditions. The thermocatalytic activity of the resulting OV-rich α-Fe2O3 NPs was assessed by evaluating the methane conversion, hydrogen formation rate, and amount of carbon deposited. The TCMD results revealed that 900 °C was the most optimal calcination temperature, as it led to the highest methane conversion (22.5%) and hydrogen formation rate (47.0 × 10-5 mol H2 g-1 min-1) after 480 min. This outstanding thermocatalytic performance of OV-rich α-Fe2O3 NPs is attributed to the presence of abundant OVs on their surfaces, thus providing effective active sites for methane decomposition. Moreover, the proposed strategy can be cost-effectively scaled up for industrial applications, whereby unsupported metal oxide NPs can be employed for energy-efficient thermocatalytic CH4 decomposition into hydrogen fuel and carbon nanomaterials.

Boosting the electrochemical performances of LiNi1/3Co1/3Mn1/3O2 cathodes via optimizing calcination temperature for lithium-ion batteries

Boosting the electrochemical performances of LiNi1/3Co1/3Mn1/3O2 cathodes via optimizing calcination temperature for lithium-ion batteries

Simultaneous fluorination and carbonation to approach a high infrared transparent magnesium fluoride

In this research study, magnesium fluoride nanoparticles were successfully produced by the fluorination and carbonation method. MgF2 nanoparticles were calcined at temperature of 100, 300, 400, 500, 600, 640, and 680 °C. Also, polycrystalline magnesium fluoride ceramics were prepared using a hot-pressing process from calcined powders. The optical, structural, and mechanical characteristics of the magnesium fluoride samples were then investigated. The X-ray diffraction proved that magnesium fluoride nanoparticles were formed with a single-phase structure and no impurities. By using simultaneous fluorination and carbonation technique, crystalline MgF2 nanoparticles with a particle size of 50–60 nm were synthesized at a minimum temperature of 100 °C. Increasing the calcination temperature led to the evaporation of the volatile products and increased the crystallinity and particle size of MgF2 nano-particles. The optimal calcination temperature of 640 °C created a ceramic MgF2 with a hardness of 560 HV, and considerable relative density of 100%, and a high transmittance of over 90% in the 3.2–5.5 μm range. The obtained results, thus, revealed that the transparency of MgF2 ceramics was a function of the porosity and the grain size distribution. The microstructure of hot-pressed MgF2 confirmed a Gaussian grain size distribution in the range of 100–1000 nm, contributing to the enhancement of densification. An intra-granular fracture occurred in magnesium fluoride, which was related to the fine-grained structure of MgF2.

Eco-efficient cement production: Investigating water treatment plant sludge and eggshell filler use in LC3 systems

The purpose of the present study was to evaluate the use of water treatment plant sludge (WTPS) (0–30% wt) and eggshell filler (0–15% wt) as replacements for clay and limestone in the limestone calcined clay cement (LC3) system, reducing the extraction of natural resources and negative environmental impacts of waste. The optimal calcination temperature of WTPS, 700 °C, was determined using the R3 test. Rheological, compressive strength, microstructural (X-ray diffraction and thermogravimetry analysis), and environmental analyses of the cement pastes were performed. For high replacement percentages (45% wt), WTPS dominated the rheological behaviour due to its high surface area. Compressive strength was satisfactory (reductions ∼10%) at 91 days, with almost total portlandite consumption by WTPS pozzolanic reactions. CO2 equivalent emissions were reduced by ∼41%, and the CO2 intensity index was decreased by ∼34%. The combined use of WTPS and eggshell filler in the LC3 system allows for high replacement percentages with satisfactory results, contributing to eco-efficient construction.

Study on catalytic degradation of toluene by copper manganese composite oxide

AbstractHerein, Cu–Mn catalysts were used to study the catalytic oxidation system of toluene, revealing the optimal preparation conditions for catalytic oxidation of toluene and the effects of other factors on catalytic performance (oxygen concentration, toluene concentration, temperature, humidity, space velocity). The as‐synthesized Cu2Mn1Ox exhibited the best catalytic activity and stability. The BET, XRD, and O2‐TPD results indicated that the synthesized Cu2Mn1 catalyst can effectively form the Cu1.4Mn1.6O4 phase at the optimal calcination temperature (500–600°C) and accelerate the toluene degradation at 220°C. Although water vapor can promote the progress of catalytic reactions, excessive water vapor tends to form competitive adsorption at active sites, inhibiting the progress of catalytic reactions. In addition, oxygen concentration plays a key role in catalytic reactions. Based on the results, it was found that at lower oxygen concentrations or higher toluene concentrations, the catalyst was easy to react with toluene to generate Cu and MnO, resulting in catalyst deactivation.

Understanding the Impact of Sintering Temperature on the Properties of Ni–BCZY Composite Anode for Protonic Ceramic Fuel Cell Application

Understanding the impact of sintering temperature on the physical and chemical properties of Ni-BaCe0.54Zr0.36Y0.1O3-δ (Ni-BCZY) composite anode is worthy of being investigated as this anode is the potential for protonic ceramic fuel cell (PCFC) application. Initially, NiO–BCZY composite powder with 50 wt% of NiO and 50 wt% of BCZY is prepared by the sol–gel method using citric acid as the chelating agent. Thermogravimetric analysis indicates that the optimum calcination temperature of the synthesised powder is 1100 °C. XRD result shows that the calcined powder exists as a single cubic phase without any secondary phase with the lattice parameter (a) of 4.332 Å. FESEM analysis confirms that the powder is homogeneous and uniform, with an average particle size of 51 ± 16 nm. The specific surface area of the calcined powder measured by the Brunauer–Emmett–Teller (BET) technique is 6.25 m2/g. The thickness, porosity, electrical conductivity and electrochemical performance of the screen-printed anode are measured as a function of sintering temperature (1200–1400 °C). The thickness of the sintered anodes after the reduction process decreases from 28.95 μm to 26.18 μm and their porosity also decreases from 33.98% to 26.93% when the sintering temperature increases from 1200 °C to 1400 °C. The electrical conductivities of the anodes sintered at 1200 °C, 1300 °C and 1400 °C are 443 S/cm, 633 S/cm and 1124 S/cm at 800 °C, respectively. Electrochemical studies showed that the anode sintered at 1400 °C shows the lowest area specific resistance (ASR) of 1.165 Ω cm2 under a humidified (3% H2O) gas mixture of H2 (10%) and N2 (90%) at 800 °C. Further improvement of the anode’s performance can be achieved by considering the properties of the screen-printing ink used for its preparation.

Enhanced alpha-amylase inhibition activity of amine-terminated PAMAM dendrimer stabilized pure copper-doped magnesium oxide nanoparticles

The present work aims to prepare copper-doped MgO nanoparticles via a sol-gel approach and study their antidiabetic alpha-amylase inhibition activity with undoped MgO nanoparticles. The ability of G5 amine-terminated polyamidoamine (PAMAM) dendrimer for the controlled release of copper-doped MgO nanoparticles to exhibit alpha-amylase inhibition activity was also evaluated. The synthesis of MgO nanoparticles via sol-gel approach and optimization of calcination temperature and time has led to the formation of nanoparticles with different shapes (spherical, hexagonal, and rod-shaped) and a polydispersity in size ranging from 10 to 100 nm with periclase crystalline phase. The presence of copper ions in the MgO nanoparticles has altered their crystallite size, eventually modifying their size, morphology, and surface charge. The efficiency of dendrimer to stabilize spherical copper-doped MgO nanoparticles (ca. 30 %) is higher than in other samples, which was confirmed by UV–Visible, DLS, FTIR, and TEM analysis. The amylase inhibition assay emphasized that the dendrimer nanoparticles stabilization has led to the prolonged enzyme inhibition ability of MgO and copper-doped MgO nanoparticles for up to 24 h.

Green utilization of biomass by-product poplar leaf ash: A novel eco-friendly cementitious material for cement mortar replacement

The use of biomass for power generation is increasing. However, solving the solid biomass waste generated during the combustion process is a challenge. In order to reduce costs and the use of forestry waste, the replacement of cement in cement mortars with the same quality of poplar leaf ash was studied. The present study documents the potential of biomass ash obtained from calcined leaf ash as a supplementary cementitious. By thermogravimetric tests, 20 °C, 310 °C, 470 °C, and 650 °C were selected as the calcination temperatures. The effects of biomass ash on uniaxial compressive strength, crack extension, acoustic emission, and the microstructure of specimens at different curing ages of 7 d and 28 d were investigated. The results show that the strength of specimens mixed with 20 wt% poplar leaf ash is about 60% of cement mortar. The porosity of cement mortar specimens with biomass ash is higher than that of cement mortar. The hydration products of C-S-H and AFt are slightly less than cement mortar. To achieve the same flowability, the water-binder ratio is higher when mixed with biomass ash. As a result, the biomass ash specimens have higher porosity and lower strength. The strength of 310 °C and 470 °C is approximately 8.41% and 4.70% lower than that of 650 °C. The optimum calcination temperature for the pozzolanic activity of poplar leaf biomass ash is 650 ℃. This promotes the efficient use of biomass solid waste and the construction industry is green development.

Regulating metal-support interactions of Pd/MgAl2O4 for efficient selective hydrogenation of acetylene

Selective hydrogenation of a trace amount of acetylene to ethylene is a green and economical process to purify the ethylene stream in the olefin industry. Pd-based catalysts are widely explored for this process due to their excellent H2 and C2H2 activation abilities. However, the strong adsorption of C2H4 on metallic Pd sites often leads to the undesired over-hydrogenation product (i.e., ethane). Herein, we fabricated Pd/MgAl2O4 catalysts with tunable metal-support interactions by changing calcination temperatures to efficiently modify the electronic structure of Pd species. The Pd/MgAl2O4 with the optimized calcination temperature exhibits 96 % acetylene conversion and enhanced ethylene selectivity of 87 % due to weak adsorption of intermediates at 120 ℃, and shows excellent stability with negligible activity decay during a 50 h test. This work provides a strategy for designing catalysts with regulated metal-support interactions for selective hydrogenation processes.