Low Calcination Temperature Research Articles

Improved Electrochemical Performance of Spinel LiNi0.5Mn1.5O4 Cathode Materials with a Dual Structure Triggered by LiF at Low Calcination Temperature.

High-voltage spinel LiNi0.5Mn1.5O4 (LNMO), which has the advantages of high energy density, low cost, environmental friendliness, and being cobalt-free, is considered one of the most promising cathode materials for the next generation of power lithium-ion batteries. However, the side reaction at the interface between the LNMO cathode material and electrolyte usually causes a low specific capacity, poor rate, and poor cycling performance. In this work, we propose a facilitated method to build a well-tuned dual structure of LiF coating and F- doping LNMO cathode material via simple calcination of LNMO with LiF at low temperatures. The experimental results and DFT analysis demonstrated that the powerful interface protection due to the LiF coating and the higher lithium diffusion coefficient caused by F- doping effectively improved the electrochemical performance of LNMO. The optimized LNMO-1.3LiF cathode material presents a high discharge capacity of 140.3 mA h g-1 at 1 C and 118.7 mA h g-1 at 10 C. Furthermore, the capacity is retained at 75.4% after the 1000th cycle at 1 C. Our research provides a concrete guidance on how to effectively boost the electrochemical performance of LNMO cathode materials.

Hierarchical Zeolite from Coal Fly Ash Using the Biosurfactant Manosyleritritol Lipids-B as a Novel Green Mesoporogen Agent

The hierarchical zeolite 13X (SiAl = 1.50) was synthesized from coal fly ash using an alternative template for the first time. The manosyleritritol lipids-B (MEL-B) > 95% purity, a biosurfactant from Pseudozyma tsukubaensis, was used as a pore directing agent in a two-step process. The hierarchical zeolite was pre-treated with oxalic acid and subsequently subjected to desilication with ammonium hydroxide aided by MEL-B using a hydrothermal reactor at 150 ºC for 5 h. The acid pretreatment was effective with 12.10% structural aluminium removal, since it increased the Si/Al ratio from 1.50 to 1.71 and also preserved the crystalline structure for the dealuminated zeolite with 20 mM oxalic acid. The zeolite, treated with 0.55 g of MEL-B, showed remarkable textural properties, with a pore diameter of 3.72 nm, a mesopore volume of 0.520 cm3/g, a high surface area of 418 m2/g and a total volume of 0.787 cm3/g. Thermal analysis showed that the biosurfactant degrades at 172 ºC, lower temperature than the synthetic surfactants. Regarding the experiments with 0.25 g of MEL-B, it was possible to increase the pore diameter by 40.8% due to the high molecular weight of the biosurfactant (893.9 g/mol), which provided a notable increase in the textural and morphological properties of the zeolites. The high performance in the generation of secondary porosity, low environmental impact, lower calcination temperature, low biosurfactant mass required to generate hierarchical pores are promising technical implementation on inorganic-bio-nanomaterials technology.

Effect of Calcination Temperature and Time on the Synthesis of Iron Oxide Nanoparticles: Green vs. Chemical Method

Nowadays, antioxidants and antibacterial activity play an increasingly vital role in biosystems due to the biochemical and biological reactions that involve free radicals and pathogen growth, which occur in many systems. For this purpose, continuous efforts are being made to minimize these reactions, including the use of nanomaterials as antioxidants and bactericidal agents. Despite such advances, iron oxide nanoparticles still lack knowledge regarding their antioxidant and bactericidal capacities. This includes the investigation of biochemical reactions and their effects on nanoparticle functionality. In green synthesis, active phytochemicals give nanoparticles their maximum functional capacity and should not be destroyed during synthesis. Therefore, research is required to establish a correlation between the synthesis process and the nanoparticle properties. In this sense, the main objective of this work was to evaluate the most influential process stage: calcination. Thus, different calcination temperatures (200, 300, and 500 °C) and times (2, 4, and 5 h) were studied in the synthesis of iron oxide nanoparticles using either Phoenix dactylifera L. (PDL) extract (green method) or sodium hydroxide (chemical method) as the reducing agent. The results show that calcination temperatures and times had a significant influence on the degradation of the active substance (polyphenols) and the final structure of iron oxide nanoparticles. It was found that, at low calcination temperatures and times, the nanoparticles exhibited small sizes, fewer polycrystalline structures, and better antioxidant activities. In conclusion, this work highlights the importance of green synthesis of iron oxide nanoparticles due to their excellent antioxidant and antimicrobial activities.

Quasi-HKUST-1 Nanostructures with Enhanced Catalytic Activity and Water Stability for Bacteria-Infected Diabetic Wound Therapy

Metal–organic frameworks (MOFs), a type of nanomaterial, are generating increasing interest in mimicking the structure and function of natural enzymes for sensors and therapeutics. Their catalytic and therapeutic efficiencies, however, are subpar due to their limited catalytic activity and structural stability. Quasi-MOFs (Q-MOFs) exhibit improved metal–carrier interactions and provide synergistic catalysis by exposing inorganic nodes to the object species while retaining a portion of the porous structure of MOFs. In this work, a quasi-Cu-based metal–organic framework was designed to improve bacteria-infected diabetic wound therapy. A series of quasi-HKUST-1 (QHKUST-1) that were created from the low-temperature calcination of HKUST-1 were used for the initial catalytic reaction. Then, the optimal QHKUST-1 has enhanced peroxidase activity to catalyze H2O2 to generate hydroxyl groups for antibacterial therapy. Comparing the previously water-sensitive HKUST-1 to the enhanced moisture stability and catalytic capabilities of QHKUST-1. Furthermore, cell migration experiments demonstrate that QHKUST-1 can promote cell migration more effectively than HKUST-1. Finally, animal experiments indicated that QHKUST-1 can effectively facilitate bacteria-infected diabetic wound healing with good antibacterial activity and biocompatibility. This work highlights the potential of Q-MOF for antibacterial therapy and shows significant promise for the future management of bacterially infected wounds.

Fabrication of TiO2/Fe2O3/g-C3N4 ternary photocatalyst via a low-temperature calcination and solvothermal route and its visible light assisted photocatalytic properties

This study reported the fabrication of TiO2/Fe2O3/g-C3N4 ternary Z-scheme photocatalyst via low-temperature calcination followed by a nonaqueous route with tunable particle size and strong interfacial contact. The subsequent Fe2O3/g-C3N4 and TiO2/Fe2O3/g-C3N4 were investigated in terms of structure, morphology, optical properties, and surface chemical composition analysis via transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), energy dispersive x-ray spectroscopy (EDX), UV–visible spectroscopy, and photoluminescence spectroscopy (PL). The crystalline nature of the samples was investigated by X-ray diffraction (XRD) and HRTEM. Under visible light, the photocatalytic capabilities of as-fabricated TiO2/Fe2O3/g-C3N4 were examined by degrading Rhodamine B (RhB), and an enhancement in photocatalytic efficacy was found. TiO2 works as a primary photosensitizer, providing extra photoinduced electrons, while Fe2O3 acts as a “bridge” for electron transport from the TiO2 moiety to the g-C3N4 thereby establishing an indirect charge transport pathway based on the Z-scheme. Radical scavenging tests were conducted to further explore the cause of increased activity and degradation mechanisms. The proposed technique might be a viable option for the removal of rhodamine b compounds and remedying freshwater reservoirs.

Investigation of the properties of reactive MgO-based cements and their effect on performance

Reactive MgO cement (RMC) is a promising alternative cementitious material benefiting from a relatively low calcination temperature during its production and strength development in concrete formulations linked with its CO2 sequestering capacity. One of the main challenges with RMC is the variations in its performance in line with the significant differences observed in the properties of the main phase, MgO. To identify and analyze the effects of these properties on the performance of RMC, this study presents a detailed characterization of 9 commercial RMC powders from different sources and precursors and an investigation of their performance in terms of reaction mechanisms and strength development. The results showed that the progress of hydration was highly dependent on the reactivity of RMC, whilst the early stages of the reaction were influenced by the purity. Additionally, agglomeration ratio revealed a strong correlation with the strength after 7 days of carbonation curing and 28 days of hydration. Finally, a regression analysis was employed to propose a model for the prediction of strength based on the initial properties of the RMC powder. The results emerging from this study can serve as a guideline for the selection of most suitable RMC-based binders for various building applications.

Effect of dehydroxylation/amorphization degree of bentonite on the microstructure, thermal stability, and mechanical strength of basalt epoxy composites

Calcination of smectite clays such as bentonite is tricky due to their 2:1 aluminosilicate structure. Low calcination temperature has minimal effect on the dehydroxylation, specific surface area (SSA), and crystalline nature of bentonite clays whereas high calcination temperature leads to removal of structural water (dehydroxylation) and amorphous nature but significant agglomeration of clay particles. The synergy between the dehydroxylation and amorphization of calcined bentonite clays in improving the thermal, mechanical, and wear properties of basalt epoxy composites was investigated. The process of dehydroxylation/amorphization of bentonite clay was characterized by XRD, FTIR, and BET. The performance of basalt epoxy composites with as received bentonite (ARB) clay were compared with calcined bentonites. The composites with calcined bentonite at 800 °C showed improved microstructure in HR-FESEM due to the synergy between dehydroxylation and amorphization of bentonite clays which further improves the thermal stability and mechanical performance of basalt epoxy composites.

Dielectric properties of low-temperature sintered forsterite (Mg2SiO4) using high-dispersion and nanoparticle-based solid-state reaction process

Dielectric materials with low dielectric constant and low loss are in high demand due to the rapid development of telecommunication systems toward 5G and 6G. In this work, a modified solid-state reaction method is reported for the synthesis of low dielectric constant forsterite (Mg2SiO4) at low calcination temperatures by using MgO and fumed silica nanoparticles (NPs). The forsterite phase was obtained at 1000 °C, where the sintering temperature was reduced from 1500 °C to 1200 °C. As-synthesized forsterite has a low dielectric constant of 3.9 with low tan δ = 0.00047 at 1 GHz. Low-temperature sintered forsterite is suitable for microelectronics applications.

Hydrogen-sieving zeolitic films by coating zeolite nanosheets on porous polymeric support

The synthesis of high-performance gas-sieving zeolitic film is challenging because it involves seeded secondary growth which is complex and difficult to reproduce. Additionally, expensive asymmetric inorganic porous supports are often needed for calcination of the zeolite films. Herein, scalable preparation of H2-sieving RUB-15 nanosheet films is reported bypassing the need for secondary growth and expensive supports. A novel, low-cost, thermally-robust, porous polybenzimidazole copolymer (PBI-AM Fumion®) support is prepared which allows deposition of thin, compact, and oriented RUB-15 nanosheets films without cracks or pinhole defects. The film hosts two transport pathways, H2-sieving six-membered silicate rings in the nanosheets and nonselective intersheet gaps maintained by the organic guest species in the gallery spacing. The latter is eliminated by a low-temperature (330 °C) calcination where the crystalline order in the nanosheets is preserved. The resulting zeolitic films yielded H2 permeances of 100–400 GPU and H2/CO2 selectivities above 20 at temperatures above 200 °C. The facile and scalable fabrication procedure with an attractive H2-sieving performance at elevated temperatures make these membranes promising for pre-combustion carbon capture.

Interface and Defect Engineering of a Hollow TiO2@ZnIn2S4 Heterojunction for Highly Enhanced CO2 Photoreduction Activity

Rational engineering of the interfaces or defects of heterojunctions provides an effective strategy to improve their photocatalytic performance but is still a challenge. Herein, we present an ingenious calcination strategy of simultaneously introducing sulfur vacancies and enhancing the interfacial interaction for a hollow TiO2@ZnIn2S4 heterojunction, thus greatly improving the photocatalytic CO2 reduction activity. The low-temperature calcination strategy makes the heterojunction possess both abundant sulfur vacancies and strong interfacial interaction, which lead to an enhanced CO2 photoreduction activity with a CO evolution rate of 1330 μmol g–1 h–1, much higher than that of the sample without calcination treatment (639 μmol g–1 h–1). The significantly boosted photocatalytic performance can be ascribed to the improved transfer and separation of photogenerated charges resulting from the intimate heterojunction interface, as well as the strengthened visible-light absorption due to the rich sulfur vacancies. This work presents a feasible and convenient method to optimize the performance of the heterojunction photocatalysts by designing the interfaces and defects.

Grain Boundary-Rich Copper Nanocatalysts Generated from Metal-Organic Framework Nanoparticles for CO2 -to-C2+ Electroconversion.

Due to severe contemporary energy issues, generating C2+ products from electrochemical carbon dioxide reduction reactions (eCO2 RRs) gains much interest. It is known that the catalyst morphology and active surface structures are critical for product distributions and current densities. Herein, a synthetic protocol of nanoparticle morphology on copper metal-organic frameworks (n-Cu MOFs) is developed by adjusting growth kinetics with termination ligands. Nanoscale copper oxide aggregates composed of small particulates are yielded via calcining the Cu-MOF nanoparticles at a specific temperature. The resulting nanosized MOF-derived catalyst (n-MDC) exhibits Faradaic efficiencies toward ethylene and C2+ products of 63% and 81% at -1.01V versus reversible hydrogen electrode (RHE) in neutral electrolytes. The catalyst also shows prolonged stability for up to 10h. A partial current density toward C2+ products is significantly boosted to -255mA cm-2 in an alkaline flow cell system. Comprehensive analyses reveal that the nanoparticle morphology of pristine Cu MOFs induces homogeneous decomposition of organic frameworks at a lower calcination temperature. It leads to evolving grain boundaries in a high density and preventing severe agglomeration of copper domains, the primary factors for improving eCO2 RR activity toward C2+ production.

In situ insight into the low-temperature promotion of ZIF-67 in electrocatalytic oxygen evolution reaction

An efficient electrocatalyst is crucial for sustainable hydrogen-fuel production, where cobalt oxyhydroxide is one of the most active catalysts for alkaline water splitting. Here, we designed a series of Co-based catalysts fabricated by direct low-temperature calcination of ZIF-67 for electrocatalytic oxygen evolution reaction (OER). Interestingly, the treatment of the pristine ZIF-67 by the temperature of only 200 °C was found to induce the most electroactive composition with a high electrochemically active surface of 373.5 cm2 and turnover frequency of 129.7 s−1, while a high specific surface area (1745 m2·g−1) is preserved. It resulted in a robust catalyst with a low overpotential of 317.8 mV at 10 mA·cm−2 and accelerated charge transfer, leading to improved performances in electrochemical energy conversion from water. Moreover, using in situ spectroscopy, XRD and microscopic techniques the active intermediates, for example, M-O, M-OH, and M-OOH were revealed and thus the exact mechanism of the reaction was proposed. Due to the formation of active species a lattice oxygen mechanism (LOM) was revealed.

Effect of low calcination temperature on the corrosion inhibition performance of biomass based Na 2 SiO 3 on mild steel immersed in tap water

Effect of low calcination temperature on the corrosion inhibition performance of biomass based Na ₂ SiO ₃ on mild steel immersed in tap water

Sintering Properties of Tetragonal Zirconia Nanopowder Preparation of the NaCl + KCl Binary System by the Sol–Gel–Flux Method

Tetragonal zirconia nanopowders (3Y-TZP NPs) stabilized by 3 mol % Y2O3 were synthesized by a novel sol–gel–flux method. The effects of calcination temperature, Y2O3 content, and molten salt system (NaCl + KCl binary system and NaCl unary system) on the phase composition and morphology of nanopowders (NPs) were investigated. Meanwhile, the sintering properties of the prepared 3Y-TZP NPs were studied. The 3Y-TZP NPs and sintered ceramics were characterized by thermogravimetry-differential scanning calorimetry (TG-DSC), X-ray diffraction (XRD), Raman spectroscopy, scanning electron microscopy (SEM), transmission electron microscopy (TEM), Brunauer–Emmett–Teller (BET) analysis, and X-ray fluorescence (XRF) spectroscopy. The results show that the optimum calcination temperature for obtaining dispersed ZrO2 NPs is reduced from 800 to 660 °C when the NaCl unary system is substituted by the NaCl + KCl binary system. 3Y-TZP NPs with a single tetragonal phase are obtained in the NaCl + KCl binary system when Y2O3 content in the raw material is 5 mol %. The average particle size of the obtained ZrO2 NPs is reduced from 47.25 nm in the unary system to 26.18 nm in the binary system because of the lower calcining temperature. Furthermore, the 3Y-TZP NPs obtained in the binary system have narrower particle size distribution and better sintering performance than ZrO2 NPs obtained in the unary system. After sintering for 4 h at 1200 °C, the former generated 3Y-TZP ceramics with higher density and finer grain size. This work produced narrow-distributed well-dispersed 3Y-TZP NPs with quasi-spherical morphology, which are good candidates for the applications, including oxygen sensors and thermal barrier coatings.

Flexible droplet printing of prominently luminescent patterns of europium-doped yttrium oxide nanospheres

Flexible techniques for producing luminescent patterns with high-resolution and moderate efficiency at the microscale are potentially important for pattern display, customized anti-counterfeiting and data security. An innovative droplet-based aerosol jet printing procedure has been developed for the creation of prominently luminescent patterns of europium-doped yttrium oxide (Y2O3:Eu3+) inorganic phosphors in case of a rather low calcining temperature. Microscale luminescent patterns of pomegranate-shaped Y2O3:Eu3+ nanospheres were effectively created by synchronizing the droplet deposition behavior and the microreactions therein. The deposition temperature was crucial to the pattern development accompanying a morphological transformation from dense film to spherical nanostructures by providing an anisotropic evaporation regime. The red emission of the printed luminescent patterns was nearly identical to that of the equivalents calcined at 1000 °C, indicating the possibility for future applications in flat panel display systems.

Case Study on the Reproducibility of Characterizing the Electrocatalytic Activity of La1−xSrxMnO3 in ORR

The electrocatalytic activity characterization of the oxygen reduction reaction (ORR) is commonly characterized using a rotating disk electrode (RDE) with linear sweep voltammetry (LSV) or cyclic voltammetry (CV) measurements. Despite the wide application of this method in the literature, its reproducibility and comparability are rarely mentioned in articles. LSV and CV are sensitive to experimental conditions, thus the reproducibility is a significant concern. In this article, the perovskite oxides La1−xSrxMnO3 (LSMOx, x = 0, 0.1, 0.2, 0.3, 0.4, 0.5) are chosen for the case study to measure their electroactivity using the RDE method. The main elements that influence the reproducibility of the experiment are presented and the corresponding explanations as well as the means for ensuring the reproducibility are given. Through the case study of LSMOx with variations in x and calcination temperatures, the values for the kinetic current of ORR on different catalysts are compared. It is found that doping ratios above 0.1 are associated with higher ORR electroactivity, with around a 50 mV difference in ORR onset potential between x > 0.1 and x = 0.1, which is in accordance with the results of reported works, whereas there is no significant difference when x = 0.2–0.5. Calcination temperature has little influence on the electroactivity of LSMOx, resulting in only a slight advantage at lower calcination temperatures, with an ORR onset potential that is around 10 mV more positive.

Metal organic framework derived NiO x nanoparticles for application as a hole transport layer in perovskite solar cells.

NiO x as a hole transport layer (HTL) has gained a lot of research interest in perovskite solar cells (PSCs), owing to its high optical transmittance, high power conversion efficiency, wide band-gap and ease of fabrication. In this work, four different nickel based-metal organic frameworks (MOFs) using 1,3,5-benzenetricarboxylic acid (BTC), terephthalic acid (TPA), 2-aminoterephthalic acid (ATPA), and 2,5-dihydroxyterephthalic acid (DHTPA) ligands respectively, have been employed as precursors to synthesize NiO x NPs. The employment of different ligands was found to result in NiO x NPs with different structural, optical and morphological properties. The impact of calcination temperatures of the MOFs was also studied and according to field emission scanning electron microscopy (FESEM), all MOF-derived NiO x NPs exhibited lower particle size at lower calcination temperature. Upon optimization, Ni-TPA MOF derived NiO x NPs calcined at 600 °C were identified to be the best for hole transport layer application. To explore the photovoltaic performance, these NiO x NPs have been fabricated as a thin film and its structural, optical and electrical characteristics were analyzed. According to the findings, the band energy gap (E g) of the fabricated thin film has been found to be 3.25 eV and the carrier concentration, hole mobility and resistivity were also measured to be 6.8 × 1014 cm-3; 4.7 × 1014 Ω cm and 2.0 cm2 V-1 s-1, respectively. Finally, a numerical simulation was conducted using SCAPS-1D incorporating the optical and electrical parameters from the thin film analysis. FTO/TiO2/CsPbBr3/NiO x /C has been utilized as the device configuration which recorded an efficiency of 13.9% with V oc of 1.89 V, J sc of 11.07 mA cm-2, and FF of 66.6%.

The synthesis of zeolitic imidazolate framework/prussian blue analogue heterostructure composites and their application in supercapacitors

ZIF-67/PBA heterostructure composites was prepared by the ion-exchange method with ZIF-67 nanoparticles as host MOFs. The electrochemical performance of the ZIF-67/PBA heterostructure composites improved after low-temperature calcination.

Low-dimensional high entropy oxide (FeCoCrMnNi)3O4 for supercapacitor applications.

Previous studies have found that high entropy oxides can be used as electrode materials for supercapacitors. However, there is still the problem of their low energy density. We tried to increase the energy density while increasing the specific capacitance of high entropy oxides from the potential window. Transition metal elements Fe, Co, Cr, Mn and Ni were selected for their electrochemical activity, and high entropy oxides were prepared by a sol-gel method under different calcination temperatures. The calcination temperature affects the structural morphology and crystallinity of the high entropy oxides and thus also affects the electrochemical performance. The spinel-phase (FeCoCrMnNi)3O4 with a high specific surface area of 63.1 m2 g-1 was prepared at a low calcination temperature of 450 °C. The specific capacitance is 332.2 F g-1 at a current density of 0.3 A g-1 in 1 M KOH electrolyte with a wide potential window of (-1, 0.6). An improved energy density of 103.8 W h kg-1 is reached via the designed microstructure of the high entropy oxide electrode.

Influence of low-temperature calcination of coal ash with alkaline agents on efficiency of valuable component recovery

Influence of low-temperature calcination of coal ash with alkaline agents on efficiency of valuable component recovery