Calcination Conditions Research Articles

Influence and Mechanism of Structural Characteristics of Limestone on Quicklime Reaction Activity

Quicklime (CaO) is extensively used in metallurgy, chemical engineering, materials science, and greenhouse gas reduction due to its high reactivity, low energy consumption, and environmental benefits. It is considered as one of the most promising raw materials for nanomaterial synthesis and carbon dioxide capture. Previous studies have predominantly focused on the impact of limestone composition and calcination condition. Recent research, however, suggests that the structural characteristics of limestone also play a crucial role in determining the reactivity of quicklime. This study investigates the effect of limestone structure on quicklime reactivity and provides a mechanistic analysis. Three types of limestone with varying structures—clastic-structured, transitional-crystalline-structured, and crystalline-structured—were selected for experiments under different calcination times. The results indicate that quicklime produced from clastic-structured limestone exhibits the highest reactivity. The observed differences in quicklime reactivity can primarily be attributed to the following factors: (1) Clastic-structured limestone possesses larger pore volume and specific surface area, which enhance heat conduction and ensure the uniform decomposition of calcite across various regions. (2) The rock-forming calcite particles are fine and small, allowing for the simultaneous decomposition of the outer shell, middle, and core during heating. This prevents “overburning” of the shell or “underfiring” of the core, thereby improving the overall reactivity. Based on these findings, we propose that fine-grained, high-purity clastic-structured limestone is more favorable for producing high-activity quicklime.

Corrigendum to “Influence of calcination conditions on deep eutectic solvents (DES) leaching efficiency of light rare earth elements in bastnasite ore” [Miner. Eng. 220 (2025) 109087

Corrigendum to “Influence of calcination conditions on deep eutectic solvents (DES) leaching efficiency of light rare earth elements in bastnasite ore” [Miner. Eng. 220 (2025) 109087

Structure, and Phase Transformations of HPM-3: A Layered Precursor of the Neutral Aluminophosphate with JSN Topology.

The structure of HPM-3, a layered aluminophosphate prepared using 1,2,3-trimethylimidazolium (123TMI) as an organic structure-directing agent by the fluoride route, has been solved by continuous rotation electron diffraction (cRED), and Rietveld refined against synchrotron powder X-ray diffraction data. Charge balance of the occluded cation is achieved through F- anions and dangling Al(OP)3OH groups. Half of the Al is pentacoordinated in negatively charged Al(OP)4-F-Al(OP)4 pairs. The layers in HPM-3, denoted as jsn, are observed in the fully connected metalloaluminophosphate molecular sieves with JSN topology. Thus, HPM-3 can be a precursor to a JSN metal-free aluminophosphate if a topotactic condensation can be reached, which proved to be difficult but feasible. Treatments under different conditions resulted in a number of known (PST-27 and AlPO4-5 by a disruptive transformation) or new phases (through mild thermal treatments). Among the latter, a layered phase with a shorter interlayer space, denoted as HPM-3S, contains half the amount of organic as HPM-3. This is afforded by the capability of 123TMI compounds to sublimate at relatively low temperatures. HPM-3S still contains the same jsn layers. Therefore, the transformation of HPM-3 into HPM-3S is topotactic but without reaching condensation. Among the phases appearing under calcination conditions at relatively low temperature (<350 °C), we observed solids compatible with the JSN topology, but with poor crystallinity. This is attributed to a wrong alignment in HPM-3 of the dangling Al(OP)3OH and P(OAl)3═O that should connect adjacent layers in a topotactic condensation, which favors 1-dimensional stacking disorder by random shifts of layers during the thermal treatments. However, detemplation at a much lower temperature (175 °C) using O3 finally afforded an aluminophosphate molecular sieve with JSN topology with only moderate stacking disorder. This is just the third reported 2D-to-3D topotactic condensations in aluminophosphates.

Optimizing calcination for low-grade calcined kaolinite clay: Reactivity and energy consumption

The cement industry is actively seeking sustainable strategies to enhance efficiency and reduce its environmental influences. Calcined kaolinite clay (CC) has emerged as a promising supplementary cementitious material (SCM) that offers significant cost and carbon emission reduction emissions compared to traditional materials. However, the variability in calcination conditions due to differing procedures and clay properties often leads to sub-optimal outcomes, diminishing pozzolanic reactivity and strengths. To address this, we developed an empirical model that accurately predicts energy consumption in relation to the metakaolin (MK) transformation ratio, enabling more efficient and sustainable production processes. Our study investigates the effects of different calcination conditions on low-grade CC by analyzing its physical and chemical characteristics, thermal decomposition, reactivity, and thermodynamics. We identified optimal calcination conditions at 800°C for 180 minutes using an electric furnace, achieving the highest pozzolanic reactivity and mechanical strength while enhancing the slump value by up to 40 %. The proposed model demonstrates a robust correlation coefficient of approximately 0.97, providing reliable energy consumption predictions across various calcination scenarios. This research provides valuable insights into balancing energy efficiency with material performance in low-grade CC calcination processes to augment sustainable development initiatives of the cement industry.

Promoting Sustainability in the Cement Industry: Evaluating the Potential of Portuguese Calcined Clays as Clinker Substitutes for Sustainable Cement Production

The cement industry significantly contributes to global CO2 emissions, posing several challenges for a future low-carbon economy. In order to achieve the target established by the European Sustainable Development Goals of reaching carbon neutrality by 2050, the European Cement Association (Cembureau) has devised a comprehensive roadmap based on five key approaches, referred to as the 5C strategies. Portland clinker is one of the crucial concerns, since its production emits over 60% of the cement manufacturing emissions. Therefore, supplementary cementitious materials (SCMs) to partially replace clinker content in cement have gained significant attention in providing alternatives to traditional clinker in cement production. This paper evaluates the potential of Portuguese calcined clays (CCs) as viable substitutes for clinker to enhance sustainability in cement manufacturing. More than 50 clays were characterised through chemical and mineralogical analyses to assess their reactivity and suitability for calcination using the strength activity index (SAI), along with XRD, XRF, and TGA techniques. This study investigated the calcination conditions that provide the best clay reactivity, which were subsequently used for calcination. This investigation is part of a project to evaluate the behaviour of calcined clays through mechanical, hydration, and durability properties. The findings indicate that Portuguese calcined clays exhibit promising pozzolanic activity. Furthermore, these clays could significantly reduce CO2 emissions and raw material consumption in cement production. This research underscores the potential of local calcined clays as a sustainable clinker substitute, promoting eco-friendly practices in the construction industry.

Highly Active Iridium Doped Titanium-Spinels for the Acidic Oxygen Evolution Reaction in PEM-Water Electrolysers

Introduction: In proton exchange membrane water electrolysers (PEMWE) the oxygen evolution reaction (OER) is the rate determining step and currently catalysed by scarce and expensive iridium oxides. Because of the high iridium price and limited iridium availability, electrolysers using pure IrO2 will struggle to fulfil the growing demand of affordable green hydrogen.[1] However, in the harsh environment inside a PEMWE anode, no non-noble metal catalyst with sufficient activity and stability is known.[2] A promising approach to reduce the iridium needed for the OER is to embed iridium into different titanium containing non-noble host oxides (e.g., Mg2TiO4) as we show for spinels in this work. In this way, the iridium atoms are ultimately dispersed in the host matrix. In line, the iridium mass specific activity increases and the iridium sites are stabilized through the presence of titanium inside the oxide.[3] This leads to catalysts that maintain high activity and stability with significantly lower iridium content than pure IrO2, even at thermodynamically favoured elevated temperatures.[4]Materials and methods: Metal-oxides with different iridium molar fractions are synthesized via a modified sol-gel approach. The successful inclusion of iridium in the non-noble oxide crystal structure is proven by XRD and ICP measurements. After further analysis (e.g., SEM, conductivity, surface area (N2-physisorption and ECSA)), the OER-activity is determined by half-cell experiments on a rotating-disc-electrode (RDE). Additionally, the catalysts are aged for one to several days at elevated temperature (> 150 °C) in a wet atmosphere to get an idea of the catalyst’s structural behaviour for the subsequent application. First attempts to test the catalyst in a full PEMWE-cell are performed as well. AlfaAesar® IrO2 (AA-IrO2) is used as a reference catalyst.Results and discussion: The different investigated iridium containing spinels show an enhanced iridium mass specific activity compared to the commercially available iridium oxide. Our best performing material Mg2Ti0.7Ir0.3O4 has around triple the iridium mass specific activity at 1.575 V vs. RHE than the IrO2 reference (figure 1a and b). For the activity normalized to the electrocatalytic surface area the performance increase of our catalyst is even more pronounced, indicating highly active Ir-sites. The iridium to titanium ratio as well as the calcination conditions show a strong influence on the crystallite size, ECSA and consequently the electrocatalytic activity of the system. As can be seen in the XRDs in figure 1c and d, lower calcination hold times (tcalc_hold, figure 1c) and temperatures (Tcalc, figure 1d) favour the insertion of iridium in the spinel leading to highly active catalysts. Once a second phase, assigned to rutile IrO2 forms at slightly harsher calcination conditions the OER performance drops. This depicts the importance of the right synthesis parameters. The observed highly active Ir-sites can, in line with literature, be attributed to either the restructuring of the catalyst surface[5], an activation of previously inert titanium[1] or to the interactions of the IrO6-octahedra with neighbouring metals inside the crystal structure.[6]Conclusion: Our approach significantly enhances the iridium mass specific activity of the single Ir-sites. Embedding iridium into a non-noble titanium containing host matrix therefore is a promising approach to achieve high electrocatalytic activity. Therefore, the iridium demand for the acidic OER in PEMWE decreases.

Optimizing calcination temperature to improve the compressive strength of coal gasification slag-based alkali-activated materials by reducing carbon content and adjusting polymerization degree

The efficient utilization of coal gasification slag (CGS) to prepare alkali-activated materials (AAMs) presents a significant opportunity for addressing the challenges associated with solid waste accumulation and environmental degradation. However, the aluminosilicate glass in CGS is highly polymerized, rendering it challenging to stimulate its potential reactivity. Additionally, the presence of residual carbon impedes the hydration process in AAMs, thereby limiting its applicability. This study focuses on the residual carbon content and polymerization degree of CGS after calcination treatment to overcome these challenges and improve the reactivity of CGS. Results revealed that residual carbon in CGS underwent thermal decomposition, increasing the proportion of aluminosilicate glass components. The degree of polymerization of CGS was reduced by 25 % under calcined conditions at 550°C, whereas at 700°C, CGS recrystallized, and the aluminosilicates were again highly polymerized. The highest reactivity of CGS was observed after calcination at 550°C. The 28 days compressive strength of the prepared AAM paste reached 47.5 MPa, representing an increase of 18.45 % compared to the control. This study innovatively elucidates the physicochemical properties of calcined CGS. It highlights the critical importance of controlling calcination conditions to manage the polymerization degree and phase transformations during carbon removal, thereby enhancing the reactivity and performance of AAMs.

Preparation of N-Containing Shell on Carbon Via Polymer-Coating and Application for Pt Supporting Materials

It is challenging to synthesize Pt nanoparticles supported on carbon materials (Pt/C) that are highly durable, efficient and affordable for use in proton exchange membrane fuel cells (PEMFC). The leading electrocatalysts consist of Pt supported on conductive carbon materials but existing carbon supports are prone to corrosion during repetitive start-stop cycles, leading to performance degradation [1]. Thus, stability of carbon supports used as an electron conductive Pt supporting material is also essential to improve Pt stability since carbon corrosion catalyzed by Pt also takes place at a high potential which triggers the detachment of Pt and subsequent agglomeration. The use of durable carbon supports against the oxidation is crucial to increase the PEMFC durability [2].To address this challenge, over the past decade we have developed that PEMFC Pt catalyst having poly[2,2'-(pyridine-2,6-diyl)bibenzimidazole-5,5'-diyl](PyPBI)-coated carbon as a carbon support showed excellent durability upon fuel cell accelerated durability test [3].PyPBI are selected as the N-containing precursor because PBIs having phenyl-linked and pyridyl-linked structures are used to explore the effect of N-content and the Pt metal binding affinity of PBls toward the oxygen reduction reaction (ORR) activity.In this study, we have developed a strategy to introduce a facile synthesis method for forming N-containing carbon support based on a PyPBI physisorption approach, followed by calcination. The work aimed to identify the influence of the N-containing carbon support on the resulting structure of the Pt electrocatalyst and the direction of the ORR durability.In previous study, we reported the fabrication of a metal free N-containing carbon around multi-walled carbon nanotubes and single-walled carbon nanotubes by calcination of carbon nanotube coated with metal-coordinated PyPBI [4].In this study, we applied this method to carbon balck (CB) to fabricate CB wrapped with the N-containing CB (denote N-CB) as a catalyst support with Pt. First, carbon wrapped with PyPBI were prepared according to our previous method [5]. After coordination of the composite with cobalt(Il) in methanol, the obtained complex was calcined at 600 °C for 60 min under N2 to provide the N-CB that cobalt(Il) ions served as the catalyst to promote the formation of the catalytic sites. As synthesized N-CB was subjected to the Pt depositions using H2PtCI6·6H20 and ethylene glycol as a Pt source and reducing agent, respectively, to fabricate Pt/N-CB. All investigated calcination conditions resulted in the formation of carbon structures containing nitrogen atoms. Electronic structure of Pt confirmed by X-ray photon-electron spectroscopy and the amounts of Pt in the catalysts were estimated by thermogravimetric analysis. From the transmission electron microscope, homogeneous dispersion of the Pt nanoparticles for Pt/N-C was observed. The electrochemical measurements were performed with potentiostat connected in a three-electrode configuration at room temperature using a Pt wire and an Ag/AgCl as the counter and reference electrodes, respectively. All rotating disk electrode measurements were conducted in 0.1 M HCIO4 solution. We demonstrate here that, the N-C electrocatalyst with Pt exhibits comparable ORR catalytic activity to commercial Pt/C counterpart.

N-alkylation of amines with alcohols over hydrothermally prepared Nb-W mixed oxides

Hydrothermally synthesized Nb-W mixed oxides (Nb-W-O) have been employed as a cost-effective and recyclable alternative to noble metals and homogeneous catalysts for the N-alkylation of amines with alcohols, with the model reaction of aniline and benzyl alcohol. The synergistic roles of Nb and W and the influence of calcination conditions were explored. Nb-W-O exhibited a linear packing of corner-sharing octahedra, analogous to the hexagonal tungsten bronze (HTB) structure, but without the long-range order of the HTB in the ab plane, characteristic of pseudo-crystalline materials. Calcination at 773 K in an N2 flow preserved the pseudo-crystalline phase and generated additional Brønsted acid sites, associated with reduced tungsten oxide species stabilized by Nb. The primary reaction pathway involved the activation of the benzyl alcohol by Brønsted acid sites, followed by a nucleophilic attack of the formed carbocation by the aniline. Nb-W-O demonstrated superior activity to other solid acids including metal oxides, silica-alumina, and zeolites in the N-alkylation reaction.

Promoting role of residual organic structure directing agent in skeletal butene isomerization over ferrierite

This work examines how acid site concentration (FT-IR) and strength (NH3-TPD) as well as pore mouth accessibility modulate the activity of the microporous zeolite ferrierite (H-FER) during the skeletal isomerization of 1-butene to iso-butene. Restricting the accessibility of catalyst pores and strong acid sites is achieved by selective oxidation of residual organic structure directing agent (OSDA) through precise control of calcination conditions. Because this reaction is mediated by catalytically active carbonaceous deposits, residual OSDA affects their formation. This work demonstrates that small amounts of residual OSDA (∼ 0.2 wt%) are beneficial to the reaction under industrially relevant reaction conditions in three ways. Selective poisoning of strong BAS with OSDA nearly halves the amount of dimerization and cracking byproducts and improves catalyst lifetime. Simultaneously, carbonaceous fragments of the OSDA act as coke precursors and help shorten the startup time. Hence, catalyst lifetime may be significantly improved through both optimal pretreatment conditions and by designing catalysts with an increased number of accessible pore mouths.

Densely populated single‐atom catalysts for boosting hydrogen generation from formic acid

AbstractThe single‐atom M‐N‐C (M typically being Co or Fe) is a prominent material with exceptional reactivity in areas of catalysis for sustainable energy. However, the formation of metal nanoparticles in M‐N‐C materials is coupled with high‐temperature calcination conditions, limiting the density of M‐Nx active sites and thus restricting the catalytic performance of such catalysts. Herein, we describe an effective decoupling strategy to construct high‐density M‐Nx active sites by generating polyfurfuryl alcohol in the MOF precursor, effectively preventing the formation of metal nanoparticles even with up to 6.377% cobalt loading. This catalyst showed a high H2 production rate of 778 mL gCat−1 h−1 when used in the dehydrogenation reaction of formic acid. In addition to the high density of the active site, a curved carbon surface in the structure is also thought to be the reason for the high performance of the catalyst.

Modulation of calcination conditions on the defluorination performance of nano Ce-based adsorbents: The key roles of Ce valence state and oxygen vacancy

Excessive fluoride (F−) in water environment is a widespread concern, and economical and efficient adsorption is widely used defluorination technology. In this study, a series of cerium-based adsorbents (Ce@C) with different structural properties were synthetized by adjusting the calcination conditions to explore their effect on the F− adsorption capacity of Ce@C and intrinsic mechanism. Results indicated that the best performing Ce@C had the maximum adsorption capacity (340.71 mg/g) and a wide pH working range (2–12). The adsorption process of F− conformed to the pseudo-second-order model and the Temkin model, proving that F− adsorption onto Ce@C was mainly dominated by chemisorption. Different calcination conditions altered the content of Ce(III) and oxygen vacancies in Ce@C, and their contents exhibited a significant effect on the F− adsorption performance of Ce@C, which showed a strong positive correlation (R2 = 0.982 and 0.933). Density functional theory (DFT) calculations further proved that the presence of Ce(III) and oxygen vacancies could provide richer coordination numbers to promote the complexation of F− and Ce@C. This work re-reveals the F− adsorption behavior and intrinsic mechanism onto cerium-based adsorbents, and also provides a theoretical basis for the subsequent design of cerium-based adsorbent materials for defluorination.

Balancing layered ordering and lattice oxygen stability for electrochemically stable high-nickel layered cathode for lithium-ion batteries

Despite the high-capacity nature of high-nickel cathode materials, achieving their practical implementation is challenging due to the susceptibility of atomic arrangement to calcining conditions. Extensive studies have enlightened the correlation between layered ordering and calcining conditions; nevertheless, the alterations in the electronic structure of lattice oxygen remain obscure. In this study, by comparing cathode materials with varying degrees of layered ordering, achieved through adjustments in calcination temperature and lithium equivalent, it is shown that although layered ordering increases, it compromises the electronic structure, creating a labile lattice oxygen environment. Fine structural analysis reveals that a higher local Li/O ratio in highly ordered cathode subsequently alters the band structure by narrowing the band gap between Ni 3d and O 2p, which enhances transition metal–oxygen covalency, and reduces the oxygen vacancy formation energy, adversely affecting cyclability. In highly ordered cathode, the tendency of lattice oxygen to reside within a Li-enriched environment arises from the changes in the favorability of non-paired antisite defects contingent upon the calcination temperature and lithium equivalent. This research underscores the need to balance layered ordering and lattice oxygen stability, offering important insights for the future design of high-nickel cathodes.

Hydrothermal synthesis of three-dimensional snowflake-like MgCO3@MnCO3@Mn3N2 composite materials and their application in aqueous zinc-ion battery cathodes

Aqueous zinc-ion batteries have attracted considerable interest in the energy storage sector due to their distinctive advantages. The use of water as an electrolyte enhances their environmental friendliness, and the abundant and low-cost nature of zinc resources confers a significant economic edge. Manganese-based materials, utilized as cathode materials in these batteries, offer favorable electrical conductivity, high theoretical capacity, and superior stability. The paper describes the hydrothermal synthesis of magnesium- and manganese-based composite material MgCO3@MnCO3@Mn3N2, through the optimization of the amounts of magnesium nitrate and urea, as well as the hydrothermal and calcination conditions. Under the optimal synthesis conditions, the composite material achieved a high capacity of 457.8 mAh/g at the current density of 50 mA/g, with capacity of 391.5 mAh/g at the current density of 100 mA/g. Notably, even at the current density of 200 mA/g, the capacity remained above 300 mAh/g. The SEM tests reveal that the MgCO3@MnCO3@Mn3N2 composite material exhibits three-dimensional snowflake-like morphology at the microscopic level. The EDS tests indicate a very uniform distribution of manganese and magnesium elements. Both infrared and Raman spectroscopy tests detected characteristic peaks of carbonate groups. The XPS tests show that the oxidation states of Mn and Mg elements are consistent with those of MgCO3 and MnCO3. In the XRD test, data fitting analysis indicates that the predominant components of the composite material are MgCO3 and MnCO3, with a ratio approximating 5:4. The presence of a small quantity of Mn3N2 is also identified within the composite material. The composite material synthesized under this composition exhibits superior electrochemical performance.

Precisely designed 3-stage calcination strategy for lithium-rich manganese-based cathodes with improved cycling performance

The poor cycling performance of Li-rich manganese-based (LMR) cathodes is one of the challenges that need to be urgently overcome. Enhancing the stability of the layered structure responsible for lithium-ion diffusion is an effective way to improve the cycling performance. Layered structures are mainly formed during the high-temperature solid-phase reaction, whereas the prolonged and constant-high-temperature calcination conditions in conventional calcination procedure may pose a threat to the layered structural stability. Thus, in order to optimize the formation environment of layered structures under high-temperature solid-phase reaction, we have designed suitable temperature-controlled strategies for each stage of layered structure formation, gradual maturation, and post-treatment, respectively, referred to as the 3-stage calcination strategy. This calcination strategy contributes to the formation of a more ordered and stable layered structure, which significantly improves the cycling performance of LMR cathodes (capacity retention rate of 85.2 % after 200 cycles at 1C). The shortening of the constant high temperature calcination time helps to further reduce the production cost of the batteries. The design concept of this work is to regulate the formation process of layered structures in stages, which provides inspiration for the efficient and controllable synthesis of electrode materials with excellent structural stability at low production cost.

Advanced Synthesis of Hierarchically Porous Zeolite Catalysts Utilizing Biomass Templates for the Catalytic Pyrolysis of Stearic Acid into Short-Chain Olefins.

In this study, hierarchically porous ZSM-5 catalysts were fabricated by one-pot assembling ZSM-5 particles onto diverse biomass templates (e.g., rice husk, tea seed husk, tung shell, and coconut shell), wherein the biomass template was transformed into bio-SiO2 or biochar depending on the calcination conditions. The biotemplated ZSM-5 variants, including ZSM-5(RH), ZSM-5(TSH), ZSM-5(TS), and ZSM-5(CS), exhibited significantly improved deoxygenation performance, achieving ∼100.0% deoxygenation efficiency as compared to the untemplated ZSM-5 catalyst (85.3%). Among them, the ZSM-5(TSH) catalyst exhibited the best performance, accompanied by 100% conversion, 99.6% deoxygenation rate, and 82.3% olefin selectivity. Interestingly, the product distribution over biotemplated ZSM-5 was dominant C4=-C8= (selectivity of ∼100% in total olefins), while long-chain olefins (C9=-C17=) was the major product (selectivity of 57.3%) over the untemplated ZSM-5. Moreover, molecular dynamics (MD) simulations revealed that biotemplated ZSM-5 exhibited superior diffusion coefficients of stearic acid (reaction substrate) and anthracene (coke precursor) compared to the untemplated ZSM-5, indicating higher self-diffusion rates and consequently superior activity and stability in the catalytic pyrolysis reactions. Furthermore, in situ DRIFTS results showed stearic acid over ZSM-5(TSH) primarily was converted to the C17H36 intermediate mainly via the decarboxylation route, followed by dehydrogenation pyrolysis and C-C breaking reactions into C4=-C8= products. Overall, this work developed an effective strategy for manufacturing hierarchically porous zeolite catalysts using biomass-derived bio-SiO2 or biochar as the platform.

A way to macroporous and alveolar geopolymer foams elaboration: Influence of operating parameters on porosity characteristics

Alveolar cellular foams are widely used in a wide range of applications, from aeronautics and filtration systems to chemical and transformation processes. Their porous characteristics make them a prime candidate for reactions, radiative transfer and flow. Geopolymeric foams, which have their origins in civil engineering, are materials with promising potential in terms of mechanical, thermal and acoustic resistance. As they are mainly used in civil engineering, the structures currently being developed are mainly closed-pore matrices. However, if they are to invert the field of photocatalytic oxidation processes, solar collectors or concentrated solar power plants, the supports need to develop a high exchange surface area. Metal alveolar foams have been identified as ideal but very costly supports. Geopolymeric foams could meet these requirements, but their surface areas are currently too limited for photoreactors. In this study, it is proposed to develop and optimize the operating conditions for geopolymer foam synthesis in order to impart macroporous properties and an interconnected alveolar structure. Based on two well-established synthesis methods (direct foaming and replication), operating conditions such as foaming agent and surfactant content, and drying and calcination conditions, are studied. Geopolymer foams are produced with different macroporous characteristics. We aim to define the synthesis conditions required to produce interconnected macroporous alveolar foams with milimetric pores. In civil engineering, these materials have the advantage of being easy to design, use and shape according to the application.

Beyond dopant selection: The critical grain size window as a key performance dictator for Co-free, Ni-rich cathode materials

Despite the immense potential of cobalt-free, nickel-rich cathode materials to replace their cobalt-containing counterparts in lithium-ion batteries (LIBs), their widespread adoption remains hindered by performance limitations. While extensive research has explored various doping strategies to address this challenge, the reported benefits vary significantly, suggesting an incomplete understanding of dopant influence and thus hindering the full potential of these additives. Our investigation into the effect of various dopants on Li(Ni0.95Mn0.05)O2 performance yielded a surprising discovery: the LIB performance of transition metal-doped Li(Ni0.95Mn0.05)O2 becomes remarkably consistent across different dopant types, provided the calcination conditions are optimized. Regardless of dopant type, a critical grain size window is identified as a key factor influencing the performance of the doped Li(Ni0.95Mn0.05)O2. Calcination within a specific temperature range is paramount to control this previously overlooked performance determinant, which significantly impacts grain growth, primary particle morphology, and lattice structure. This novel insight allows us to demonstrate that cost-effective dopants such as Ti can achieve performance in stabilizing Li(Ni0.95Mn0.05)O2 comparable to that of more expensive, higher-valence alternatives (e.g., Nb, Ta, W, and Mo). This discovery paves the way for developing practical material design processes that meet the stringent requirements of the LIB industry.

Effective electromagnetic wave absorption strategy: Unlocking the potential of NiCo2O4 as an absorber

This study addresses a scientific challenge by elucidating the influence of calcination temperature on the properties and electromagnetic wave absorption capabilities of NiCo2O4, a material whose performance is inherently tied to its preparation process. Specifically, we systematically investigate how varying calcination temperatures not only diversify the material’s composition and morphology but also enhance its electromagnetic wave absorption properties. By controlling the calcination temperature, we not only achieve the successful synthesis of NiCo2O4 but also unravel intricate correlations among calcination conditions, material composition, and wave absorption performance. Notably, NiCo2O4 sample calcined at 400 °C exhibits remarkable electromagnetic wave absorption, marked by an exceptional maximum reflection loss of −53.93 dB and a broad absorption bandwidth spanning 6.24 GHz. These insights contribute to advancing the frontiers of NiCo2O4 utilization, particularly in the realm of electromagnetic wave absorption and beyond, underscoring the novelty and impact of our research.

Ag-TiO2 Photovoltaic Synergistic Field-catalyzed Degradation Performance of Tetracycline

Background: Tetracycline (TC), a commonly used antibiotic, is extensively utilized in the medical sector, leading to a significant annual discharge of tetracycline effluent into the water system, which harms both human health and the environment. Objective: A novel technique was developed to address the issues of photogenerated carrier complexation and photocatalyst immobilization. Compared to traditional photocatalytic photoelectrodes, the suspended catalyst used in the photovoltaic synergy field is more stable and increases the solidliquid contact area between the catalyst and the pollutant. Methods: This paper uses sol-gel-prepared Ag-TiO2 materials for the photoelectric synergistic fieldcatalyzed degradation of TC. The study examined how the Ag doping ratio, calcination conditions, catalyst injection, pH, electrolytes, and electrolyte injection affected photoelectric synergistic fieldcatalyzed degradation. The experiments were performed in a photocomposite field with a constant 50 mA current and a 357 nm UV lamp for 60 minutes. The composites underwent characterization using XRD, TEM, and XPS techniques. Results: Ag-TiO2 photoelectric synergistic field-catalyzed reaction with 357 nm ultraviolet lamp irradiation for 60 min and a constant current of 50 mA degraded 5 mg/LTC under preparation conditions of molar doping ratio of Ti: Ag=100:0.5, roasting temperature of 500 °C, and roasting time of 2 h. The photoelectric synergistic field-catalyzed degradation process achieved a degradation rate of 90.49% for 5 mg/L TC, surpassing the combined degradation rates of electrocatalysis and photocatalysis. The quenching experiments demonstrated that the degradation rate of TC decreased from 90.49% in the absence of a quencher to 53.23%, 42.58%, and 74.52%. The presence of •OH had a more significant impact than h+ and •O2 -. Conclusion: The findings suggest that Ag-TiO2 significantly enhanced the efficacy of photoelectric synergistic field-catalyzed degradation and can be employed to treat high-saline and lowconcentration TC. This establishes a benchmark for using photoelectrocatalytic materials based on titanium in treating organic wastewater.