Thermal Activation Research Articles

Defect-engineered indium-organic framework displays the higher CO2 adsorption and more excellent catalytic performance on the cycloaddition of CO2 with epoxides under mild conditions.

In order to achieve the high adsorption and catalytic performance of CO2, the direct self-assembly of robust defect-engineered MOFs is a scarcely reported and challenging proposition. Herein, a highly robust nanoporous indium(III)-organic framework of {[In2(CPPDA)(H2O)3](NO3)·2DMF·3H2O}n (NUC-107) consisting of two kinds of inorganic units of chain-shaped [In(COO)2(H2O)]n and watery binuclear [In2(COO)4(H2O)8] was generated by regulating the growth environment. It is worth mentioning that [In2(COO)4(H2O)8] is very rare in terms of its richer associated water molecules, implying that defect-enriched metal ions in the activated host framework can serve as strong Lewis acid. Compared to reported skeleton of [In4(CPPDA)2(μ3-OH)2(DMF)(H2O)2]n (NUC-66) with tetranuclear clusters of [In4(μ3-OH)2(COO)10(DMF)(H2O)2] as nodes, the void volume of NUC-107 (50.7%) is slightly lower than the one of NUC-66 (52.8%). However, each In3+ ion in NUC-107 has an average of 1.5 coordinated small molecules (H2O), which far exceeds the average of 0.75 in NUC-66 (H2O and DMF). After thermal activation, NUC-107a characterizes the merits of unsaturated In3+ sites, free pyridine moieties, solvent-free nanochannels (10.2 × 15.7 Å2). Adsorption tests prove that the host framework of NUC-107a has a higher CO2 adsorption (113.2 cm3/g at 273K and 64.8 cm3/g at 298K) than NUC-66 (91.2 cm3/g at 273K and 53.0 cm3/g at 298K). Catalytic experiments confirmed that activated NUC-107a with the aid of n-Bu4NBr was capable of efficiently catalyzing the cycloaddition of CO2 with epoxides into corresponding cyclic carbonates under the mild conditions. Under the similar conditions of 0.10mol% MOFs, 0.5mol% n-Bu4NBr, 0.5 MP CO2, 60°C and 3h, compared with NUC-66a, the conversion of SO to SC catalyzed by NUC-107a increased by 21%. Hence, this work offers a valuable perspective that the in situ creation of robust defect-engineered MOFs can be realized by regulating the growth environment.

Thermal kinetic, mechanical and wear properties of glass fiber reinforced polyamide 6 thermoplastic composites

AbstractPolyamide 6 (PA6) thermoplastic‐based composites are often used in automobile, aerospace, marine, and biomedical applications. Here, PA6 and its composites with varied chopped glass fiber (GF) concentrations of 5, 10, and 20 mass% were fabricated by injection molding. The specimens were characterized by structural, thermal kinetic, mechanical, as well as tribological analyses. Tribological performance was evaluated in dry pin‐on‐disc test apparatus with three different levels of time, speed, and load factors. The PA6/GF composites showed high decomposition activation energy compared to pure PA6. Thermal activation, Ea increased to 46.16% with increasing of GF content up to 10 mass% in the composites compared to PA6. PA6/5GF exhibited best mechanical properties (e.g., strength = 44.46 MPa and Hardness = 45.2). Addition of GF in PA6 significantly improved tribological properties, coefficient of friction (COF) and specific wear rate (WR) besides thermal stability and mechanical properties of the composites. Especially, COF and WR of PA6/5GF composite decreased by 17%–65% and 68%–92%, respectively, compared to PA6. ANOVA statistical results determined the significant contribution of the tribological factors to the performance metrics of the composites for COF and WR. Therefore, the PA6/5GF composite would highly be useful for tie‐rod gears and bearings as a crucial structural component in automotive bodywork.

Lignin-based vitrimer containing dynamic borate ester bonds with intrinsic photoconversion and excellent photothermal remoldability

The development of photoresponsive shape memory materials based on the photothermal conversion properties of lignin and the low activation energy of the dynamic covalent borate bond is of great importance. In this paper, a kind of lignin-based vitrimer polymer (LBP) containing dynamic boronic ester bonds was prepared by a “sulfhydryl-epoxy” click reaction and etherification reaction. The results show that the rigid segment EP-EL (lignin-based epoxy resin) and BDB (2,2′-(1,4-phenylene)-bis-[4-mercapto-1,3,2-dioxaneborane]) with benzene ring structure can impart tensile strength (20.8 MPa) to the LBP, while the flexible segment PEG imparts good elongation at break (15 %). The dynamic binding and dissociation exchange mechanism of the boronic ester bonds enables LBP to exhibit thermal remodelling properties (up to 36.2 %) and water-assisted self-healing properties at room temperature (up to 49.0 %). In addition, LBP exhibits excellent thermal and light-responsive shape memory properties due to its own photothermal conversion performance (photothermal conversion efficiency up to 18.2 %) and the dynamic boronic ester bond thermal activation bond exchange mechanism. The insulating properties of LBP make it suitable for use in high temperature protection circuit devices and light-responsive circuit devices. This study provides new insights into the design and application of Vitrimer and photoresponsive shape memory polymers, and also offers a new avenue for high-value utilization of lignin.

Plastic deformation and heat-enabled structural recovery of monolithic silica aerogels

Drying shrinkage during ambient pressure drying of silica gels is made reversible by preventing condensation reactions of surface silanol groups via surface modification. This partial recovery of the gel volume and structure is referred to as the spring-back effect (SBE) and enables the production of monolithic silica aerogels by evaporative drying. The SBE is sometimes completed by annealing at mild temperatures. Similarities between drying-related deformations and deformations induced by mechanical stimuli suggest analogous underlying mechanisms. While the causes of drying shrinkage are relatively well-known, it remains unclear how the relaxation of the structure by drying and annealing occurs across the different length scales. Here we show a complete structural recovery of silica aerogels at the macro- and nano-scale enabled by annealing. We propose that residual deformations after drying and mechanical compression are caused by the entanglement of silica clusters that can be unraveled by annealing at 230 °C. The deformation under loading is interpreted as two different re-arrangement mechanisms for dry and annealed gels, by the sliding of the silica clusters along the loading direction and by the compression of large pores beyond the fractal structure, respectively. Our results demonstrate how the shape and structure of silica aerogels can be restored and controlled by thermal activation, broadening the various applications of these materials. We also emphasize how tuning silica gels to promote a two-step SBE by annealing can pave the way toward the production of larger monolithic aerogels by APD.Graphical

Enhancing Compressive Strength of Very High Volume Fly Ash Concrete Using Low Molarity Alkali Solution and Thermal Activation

Enhancing Compressive Strength of Very High Volume Fly Ash Concrete Using Low Molarity Alkali Solution and Thermal Activation

Effect of Thermoactivated Recycled Cement, Hardened Cement Powder and Hydrated Lime on the Compressive Strength of Mortars.

Thermoactivated recycled cement (RC) is a growing area of research and development in the cement industry. The approach represents a reversible process of cement hydration in which dehydrated compounds with similar characteristics to cement are obtained by means of thermal activation. To avoid CO2 emissions during the production of such RC, this study assesses the possibility of replacing ordinary Portland cement (OPC) with hardened cement powder (HCP) prepared with different proportions of hydrated lime (HL), relying on a second pozzolanic reaction, and compares it with RC mortars. Due to the thermal activation of HCP, the compressive strength increases by 11.5%. The addition of 8% HL produced an important increase in strength from 28 days to 90 days by 12.8%, although without surpassing the strength values of mortar produced only with HCP or with RC. The compressive strength results suggest the existence of a secondary pozzolanic reaction when using HCP from a cement paste source, but such a pozzolanic reaction was fully perceived in XRD patterns when using concrete as parent material, unlike cement paste, possibly due to large crystalline sand peaks that could have hindered the effective identification of smaller crystalline peaks.

Destruction of the Lithosphere beneath the SW Margin of the São Francisco Craton Evidenced by Refertilized and Deformed Mantle Xenoliths

Abstract The destruction of the cratonic root has been documented for multiple cratons worldwide and is characterized by severe lithospheric thinning, extensive extensional deformation, and intense thermal activity. Here, we present detailed petrography accompanied by comprehensive geochemical and isotopic data for peridotites, pyroxenites, and eclogites from the SW margin of the São Francisco Craton that has also been severely thinned. The diamond-bearing Canastra-1 kimberlite represents a Cretaceous intrusion from the Alto Paranaíba Igneous Province and hosts garnet-bearing mantle xenoliths from different mantle sources, revealing a complex history of metasomatism/refertilization related to superimposed tectonic events since the cratonic consolidation. Eclogites (T = 978–982°C; P ~ 4.0 GPa) and pargasite-bearing websterites (T = 875–926°C; P = 2.0–3.0 GPa) represent the shallower and colder cratonic lithosphere. Mantle-derived high-MgO eclogitic clinopyroxenes show a light rare earth element (LREE)-enriched pattern (Ce/YbN = 60.90–93.63) while both clinopyroxene and garnet present high 87Sr/86Sr ratios (0.70842–0.70912) and negative εNd values (−5.6 to −7.3). These features, supported by the reconstructed whole-rock composition, suggest a mafic protolith probably metasomatized by fluid/melt derived from the overlying sedimentary rocks. Pargasite websterites are cumulates from an evolved (SiO2-rich) and hydrated basaltic andesitic magma. These xenoliths are characterized by high concentration of LREE relative to heavy-REE (HREE) in clinopyroxene (Ce/YbN = 10.52–50.61) and pargasite (Ce/YbN = 10.26–57.06), and by the presence of Al-rich orthopyroxene. As observed in eclogites, clinopyroxene and garnet from pargasite websterites display high 87Sr/86Sr ratios (0.70894–0.71094) and strong negative εNd values (−7.2 to −13.3). Trace elements (i.e. Zr, Ti, and Y) in garnets of both rock types indicate the role of a depleted component affected by a metasomatic agent. Although we were unable to date the formation of these rocks or the metasomatic events, we suggest a possible relationship with the consolidation of Gondwana during the Neoproterozoic. Sheared lherzolites, clinopyroxenites, anhydrous websterites, and dunite are deeper fragments from the lithosphere-asthenosphere boundary (LAB: 1191–1290°C; 5.3–5.6 GPa). They have abundant kelyphitic rims around garnet grains, which indicate metasomatism promoted by the percolation of a high-temperature proto-kimberlite melt enriched in Ti, Zr, and Y. The presence of kelyphitic phlogopite with high-Ti-Cr contents reinforces this assumption. LREE-enriched clinopyroxenes (Ce/YbN = 12.06–48.02) confirm the enriched character of the silicate melt responsible for the refertilization process within the cratonic root. The proto-kimberlite metasomatism is further supported by the preferential enrichment of 87Sr/86Sr ratios (0.70560–0.70869) accompanied by positive εNd values (+1.8 to +10.10). Two-point clinopyroxene-garnet Sm–Nd isochrons yielded an average age of 120 ± 5 Ma, representing the kimberlite eruption/emplacement age of the host kimberlite. These deeper LAB xenoliths reveal intense lithospheric thinning triggered by percolation of a high-temperature proto-kimberlite melt since the early stages of Gondwana break-up during the Cretaceous, shortly before the kimberlite emplacement at 120 Ma. Therefore, they provide remarkable evidence of the destruction of the São Francisco Craton through thermal-mechanical erosion that triggered its rejuvenation.

The Impact of Biomass-Derived Graphene-like Porous Carbon Decorated with NiO Nanoparticles on the Electrochemical Performance of Lithium-Sulfur Batteries

Lithium-sulfur batteries are considered a promising next-generation energy storage system, boasting high theoretical capacity and energy density, approximately double that of LiBs [1,2]. However, challenges such as low sulfur conductivity, significant volume expansion during cycling, and the lithium polysulfides shuttle effect hinder their practical use [3]. These issues result in side reactions, irreversible loss of active material, and anode degradation, leading to a rapid decline in cell capacity stability [4].In this research, we successfully developed a sulfur cathode carbon matrix and separator modifier from rice husk through carbonization and thermal activation. The resulting graphene-like porous carbon (GPC) exhibited high efficiency as a sulfur host, enhancing the electrochemical performance of the cathode. The GPC-NiO composite also served effectively as a separator modifier, catalyzing lithium polysulfides' redox reactions and improving the overall cycling stability of lithium-sulfur batteries. In particular, the GPC@S/GPC-NiO-20 cell demonstrated an excellent initial discharge capacity of 1519 mAh g-1 at 0.2 C. Also, it delivered excellent long-term cycling, maintaining a discharge capacity of 661 mAh g-1 even after 400 cycles at 1 C, with a Coulombic efficiency exceeding 97%. It exhibited a promising rate capability of 568 mAh g-1 at 2 C and retained a discharge capacity of 603 mAh g-1 over 100 cycles at 0.2 C with a sulfur loading of 4.0 mg cm-2. Acknowledgments This research is funded by the Science Committee of the Ministry of Science and Higher Education of the Republic of Kazakhstan (Grant No. AP19677708).

(Invited) Breaking the Activity-Durability Tradeoff of Fe-N-C Fuel Cell Catalysts Via Controlling Thermal Activation Atmosphere

Fe-N-C catalysts, the most promising platinum group metal (PGM)-free oxygen-reduction catalysts, often simultaneously contain pyrrolic N- (S1) and pyridinic N (S2) -coordinated FeN4 sites. These two types of active sites show significantly different intrinsic activity and stability. S1 sites are more active but less stable compared to S2 sites. Designing a Fe-N-C catalyst, which exclusively contains active S1 sites with enhanced intrinsic stability, is highly desirable to break the activity-stability trade-off. Herein, we report a Fe-N-C model catalyst that solely comprises S1 sites prepared by adding H2 in the pyrolysis atmosphere (i.e., 10% H2/Ar). A membrane electrode assembly (MEA) with the Fe-N-C cathode demonstrated compelling activity and generated a current density of 50.8 mA cm−2 at 0.9 ViR-free (H2-O2) and 211 mA cm−2 at 0.8 V (H2-air), which have significantly exceeded the U.S. DOE 2025 targets. The highly active Fe-N-C catalyst also demonstrated improved stability during life tests and accelerated stability tests (ASTs). The knowledge obtained from experimental and theoretical results elucidates that the FeN4 site formation process can be controlled by thermal activation atmospheres, which is essential to breaking activity-stability trade-off and design viable Fe-N-C catalysts with adequate activity and stability for proton exchange membrane fuel cells.

(Invited) Atomically Dispersed Metal Electrocatalysts for CO2 to CO Conversion: From Single to Dual Metal Sites

Carbon-supported nitrogen-coordinated single-metal site catalysts (i.e., M−N−C, M: Fe, Co, or Ni) are active for the electrochemical CO2 reduction reaction (CO2RR) to CO.(1) We comprehensively engineered FeN4 and NiNx sites for electrochemical CO2 reduction to CO considering the particle sizes of the catalysts, metal content, and the M−N (M: Fe or Ni) bond structures.(2, 3)The unique M-N-C model allows us to elucidate each factor′s role exclusively regarding the promotion of CO2 reduction.(4)Optimal particle sizes and Fe content provide favorable external factors to improve mass activity. Structural changes of M−N bonds controlled by thermal activation temperatures can intrinsically enhance CO selectivity and kinetic activity. Notably, the NiN3 active sites with optimal local structures formed at higher temperatures (e.g., 1200 °C) are intrinsically more active and CO-selective than NiN4, providing a new opportunity to design a highly active catalyst via populating NiN3 sites with increased density. Further improving their intrinsic activity and selectivity by tuning their N−M bond structures and coordination is limited. We further expand the coordination environments of M−N−C catalysts by designing dual-metal active sites.(5)The Ni-Fe catalyst exhibited the most efficient CO2RR activity and promising stability compared to other combinations. Advanced structural characterization and theoretical prediction suggest that the most active N-coordinated dual-metal site configurations are 2N-bridged (Fe-Ni)N6, in which FeN4 and NiN4 moieties are shared with two N atoms. Two metals (i.e., Fe and Ni) in the dual-metal site likely generate a synergy to enable more optimal *COOH adsorption and *CO desorption than single-metal sites (FeN4 or NiN4) with improved intrinsic catalytic activity and selectivity.References Pan F, Zhang H, Liu K, Cullen D, More K, Wang M, et al. Unveiling Active Sites of CO2 Reduction on Nitrogen-Coordinated and Atomically Dispersed Iron and Cobalt Catalysts. ACS Catalysis. 2018;8(4):3116-22.Li Y, Adli NM, Shan W, Wang M, Zachman MJ, Hwang S, et al. Atomically dispersed single Ni site catalysts for high-efficiency CO2 electroreduction at industrial-level current densities. Energy & Environmental Science. 2022;15(5):2108-19.Mohd Adli N, Shan W, Hwang S, Samarakoon W, Karakalos S, Li Y, et al. Engineering Atomically Dispersed FeN4 Active Sites for CO2 Electroreduction. Angewandte Chemie International Edition. 2021;60(2):1022-32.Li J, Zhang H, Samarakoon W, Shan W, Cullen DA, Karakalos S, et al. Thermally Driven Structure and Performance Evolution of Atomically Dispersed FeN4 Sites for Oxygen Reduction. Angewandte Chemie International Edition. 2019;58(52):18971-80.Li Y, Shan W, Zachman MJ, Wang M, Hwang S, Tabassum H, et al. Atomically Dispersed Dual-Metal Site Catalysts for Enhanced CO2 Reduction: Mechanistic Insight into Active Site Structures. Angewandte Chemie International Edition. 2022;61(28):e202205632.

Carbon Cloth Electrodes for Vanadium Redox Flow Batteries

Renewable energy sources such as wind and solar are playing an increasingly important role as the decarbonization of the energy industry moves forward. However, wind and solar-based energy production fluctuates daily and seasonally. For a stable electrical grid, a large-scale energy storage system is required. One promising technology for this is the Vanadium Redox Flow Battery (VRFB), developed in the late 1980s by Maria Skyllas-Kazacos (1), which has been continuously researched and improved over the last decades.VRFBs are already commercially available but must overcome significant lifetime and efficiency challenges. Polarization and pumping losses account for a large part of the efficiency losses due to the high flow-through resistance of the electrolyte in the electrode (2). Therefore, the electrode material must be optimized to achieve high catalytic activity and excellent flow properties to enhance the battery's performance.In a previous study, we identified key factors such as the electrode's structure, wettability, and electrochemical performance. Therefore, we developed a suitable set of characterization techniques (3). This multimodal characterization approach has been applied to evaluate woven and knitted carbon cloths. We designed electrode materials with specific fiber structures and weaving and knitting patterns. The raw material for the fibers is cellulose from hemp. To successfully commercialize VRVBs, the manufacturing process of the material must be low-cost and easy to fabricate on an industrial scale. Here, the electrode materials are fabricated by weaving or knitting, a well-established technique in the textile industry for centuries, and are ideally suited for the large-scale industrial production of electrodes. After weaving or knitting, the cloths are subsequently carbonized.To understand the influence of the fabrication pattern, the flow direction, and the 3D electrode structure on the flow behavior, we used Electrochemical Impedance Spectroscopy (EIS) coupled with the Distribution of Relaxation Times (DRT) analysis (4,5). This method allows simultaneously investigating the electrochemical performance, wettability, and structure in an application-oriented, in-house-designed setup. To develop a deeper understanding of the microscopic structure of the fiber and its influence on the key factors, Scanning Electron Microscopy (SEM) and nano-X-ray computed tomography (nano-CT) were utilized. These results were combined with Dynamic Vapor Sorption measurements (DVS), which are used to investigate the wettability of the material, and Cyclic Voltammetry (CV), which accesses the electrochemical performance. Additionally, we studied the effect of thermal activation on these parameters with EIS and DRT analysis, SEM, nano-CT, DVS, CV, and X-ray photoelectron spectroscopy.The materials presented in this paper exhibited excellent electrode performance, demonstrating good wettability, high catalytic activity, and large electrochemically active surface area. These are promising examples of electrode engineering as a pathway to optimal designs of VRFBs.1. M. Skyllas‐Kazacos, M. Rychcik, R. G. Robins, A. G. Fane and M. A. Green, J. Electrochem. Soc., 133(5), 1057–1058 (1986).2. N. Bevilacqua, L. Eifert, R. Banerjee, K. Köble, T. Faragó, M. Zuber, A. Bazylak and R. Zeis, Journal of Power Sources, 439, 227071 (2019).3. K. Köble, M. Jaugstetter, M. Schilling, M. Braig, T. Diemant, K. Tschulik and R. Zeis, Journal of Power Sources, 569, 233010 (2023).4. M. Schilling, M. Braig, K. Köble and R. Zeis, Electrochimica Acta, 430, 141058 (2022).5. M. Schilling and R. Zeis, submitted. Figure 1

Exploring thermal comfort and pleasure in outdoor shaded spaces: Inspiration for improving thermal index models

Engaging in outdoor activities offers numerous benefits for physical and mental well-being, highlighting the importance of prioritizing outdoor comfort and safety. Shaded spaces are sought after during hot summers due to their lower surface temperatures and improved thermal comfort. This study conducted group walking experiments in both overhead layers and tree-shaded areas to investigate variations in thermal comfort based on different thermal environments and activity levels. The findings reveal significant differences in the thermal environment between the two areas, with tree shading reducing mean radiant temperature by approximately 3 °C and wind speed by about 1 m/s. Regardless of the walking space, the lowest thermal pleasure and comfort are experienced at a speed of 1.80 m/s. Moreover, the study demonstrates that thermal pleasure (Tp) is influenced by both the objective thermal environment and the human body's thermoregulatory mechanisms. It is also affected by subjective psychological expectations, reflecting the combined outcome of metabolic heat production, external thermal stimuli, and psychological emotions. Thus, pedestrians experienced different levels of thermal pleasure based on their walking speeds and the type of shaded space. These findings underscore the importance of integrating physiological and psychological factors into thermal index models to accurately evaluate outdoor thermal comfort conditions. The study contributes to developing improved thermal index models by enhancing their correlation with the perceived thermal sensations and considering the emotional aspect of thermal pleasure. The implications of this research can guide urban planning efforts to provide more comfortable and enjoyable outdoor shaded spaces.

Fennel (Foeniculum vulgare Mill.) essential oil: The chemical profile, biological activity, and utilization of the commercial products

Laboratory-isolated essential oils are commonly used in experiments regarding their utilization as natural antioxidant and antimicrobial agents. This study analyzed commercially available essential oils (Serbian-FSR and Russian-FRU) of fennel (Foeniculum vulgare Mill.) and added to the pork patties to investigate their possible role as natural antioxidant and antimicrobial agents. Chemical analysis of the samples showed significant differences in profiles caused by geographical origin and other environmental factors. The main compound in both samples was trans-Anethole, but it had a much higher content in Serbian oils. On the contrary, Russian oil had a high portion of anisaldehyde and linalool. These diversities are the main reason for thermal behavior and biological activity differences. The thermal analysis has shown that FSR had a crystalline form in the solid state, while FRU had an amorphous form. During heating, in FSR, a single-step weight loss was detected, while in FRU, a two-step weight loss was observed, indicating that, in addition to evaporation, components in FRU interacted with each other, forming lesser volatile molecules. After adding pork patties, Russian oil showed higher potency and better protective behavior than Serbian oil. Moreover, mixtures of these oils were added to the patties samples, and results showed higher potency when compared to individual oil samples. This indicated that minor compounds from both oils interacted and synergistically acted to prolong the shelf life of the meat samples. Commercial essential oils could be successfully utilized to prolong shelf life and provide additional intake of natural compounds significant for the human diet.

Advancing Volcanic Activity Monitoring: A Near-Real-Time Approach with Remote Sensing Data Fusion for Radiative Power Estimation

The global, near-real-time monitoring of volcano thermal activity has become feasible through thermal infrared sensors on various satellite platforms, which enable accurate estimations of volcanic emissions. Specifically, these sensors facilitate reliable estimation of Volcanic Radiative Power (VRP), representing the heat radiated during volcanic activity. A critical factor influencing VRP estimates is the identification of hotspots in satellite imagery, typically based on intensity. Different satellite sensors employ unique algorithms due to their distinct characteristics. Integrating data from multiple satellite sources, each with different spatial and spectral resolutions, offers a more comprehensive analysis than using individual data sources alone. We introduce an innovative Remote Sensing Data Fusion (RSDF) algorithm, developed within a Cloud Computing environment that provides scalable, on-demand computing resources and services via the internet, to monitor VRP locally using data from various multispectral satellite sensors: the polar-orbiting Moderate Resolution Imaging Spectroradiometer (MODIS), the Sea and Land Surface Temperature Radiometer (SLSTR), and the Visible Infrared Imaging Radiometer Suite (VIIRS), along with the geostationary Spinning Enhanced Visible and InfraRed Imager (SEVIRI). We describe and demonstrate the operation of this algorithm through the analysis of recent eruptive activities at the Etna and Stromboli volcanoes. The RSDF algorithm, leveraging both spatial and intensity features, demonstrates heightened sensitivity in detecting high-temperature volcanic features, thereby improving VRP monitoring compared to conventional pre-processed products available online. The overall accuracy increased significantly, with the omission rate dropping from 75.5% to 3.7% and the false detection rate decreasing from 11.0% to 4.3%. The proposed multi-sensor approach markedly enhances the ability to monitor and analyze volcanic activity.

Efficient extraction of Li and Rb from zinnwaldite via thermal activation and acid leaching

Lithium and its associated rubidium are regarded as the strategic metal resource, which have a wide use in many commercial products. Nowadays, the continuing growth in demand for Li resources, propelling the object of industrial exploitation will focus on low-grade, complex minerals composition and unwieldy ores. Zinnwaldite has received increasing attention as a potential lithium-containing resource in recent years. However, there are a lack of effective extraction processes for zinnwaldite. Hence, this paper proposes an effective method to extract metal cleanly and efficiently from zinnwaldite by using CaO and B2O3 as thermal activation additives and H2SO4 as the leaching agent. The results showed that the destruction of Fe-O and Si-O-Si bonds led to increased extraction efficiency. The breathing vibrations of oxygen atoms symmetric in 4- and 3-membered rings and Si-O symmetric stretch could influence the Li separation from silica skeleton. Ultimately, the 91.32 % Li, 93.09 % Rb, 81.14 % Fe, 95.00 % Al and 71.12 % K were recovered under the optimal conditions. Meanwhile, about 10 % F escaped into the air during thermal activation and the concentration of F in the leaching solution was lower than 2 mg/L. The use of B2O3 provides a valuable reference for the efficient and clean treatment of lepidolite using the salt roasting method.

Evaluating thermal activated coal gangue as alternative filler in asphalt binder using rheological experiments and molecular dynamic simulation

Asphalt mastic, an important raw material in asphalt pavement, is a mixture of asphalt binder and mineral filler. This study utilized coal gangue (CG) as alternative of natural filler in asphalt mastic, which has benefits to recycling solid waste and saving non-renewable resource. In order to achieve performance improvement of CG asphalt mastic (CGAM), thermal activation approach was applied to treat CG particles from 450 ℃ to 900 ℃. Before and after treatment, the surface morphology, mineral components and size distribution were characterized via scanning electron microscopy (SEM), X-ray diffraction (XRD), X-ray fluorescence (XRF) and laser particle size analyzer. Meanwhile, the dynamic shear rheometer (DSR) and bending beam rheometer (BBR) experiments were conducted to compare the rheological responses of CGAM at high and low temperatures. Further, the interfacial behavior between asphalt binder and CG filler is simulated by molecular dynamic (MD) method, aiming to explore the interaction mechanism at atomistic scale. Results show that the activated CG possesses a smaller particle size and a rougher surface by comparison in virgin one (i.e., unactivated CG). And the calcination process results in the crystal phase transition of CG and the proportion increase of alkali minerals, contributing to the stronger interaction ability and higher adhesion energy with asphalt binder. Owing to the positive changes of CG during calcination process, the corresponding CGAM exhibits superior deformation resistance property under recycling loads at high temperature and flexural creep ability at low temperature, especially when the calcination temperature rises to 750 ℃.

Enhanced passivity of reinforcing steel in cementitious materials with thermally-activated red mud

Red mud (RM) is a solid waste from aluminium industry that can be used as an emerging supplementary cementitious material, and it has beneficial effects on the corrosion resistance of reinforcing steel in concrete. However, the low reactivity of RM reduces the comprehensive performance of cementitious materials, thereby limiting its widespread application in concrete. In this study, RM was thermally activated and the phase transformation behavior of the thermally-activated RM (TA-RM) was studied. Additionally, the passivation behavior of steel in extract solutions and mortars containing RM with and without thermal activation was investigated using electrochemical methods, surface characterization techniques and compositional analysis. The results showed that the reactivity of RM was effectively improved by the thermal activation treatment due to the phase transformation, and the enhanced steel passivity was observed in both extract solution and mortar with TA-RM. Compared to steel exposed to extract solutions, the mortar containing TA-RM could provide an additional protection for the embedded steel by forming a compact steel-mortar interface, further improving its passivation ability.

Regulating the Scaling Relations in Ammonia Synthesis through a Light-Driven Bendable Seesaw Effect on Tailored Iron Catalyst.

Advancing the energy-intensive Haber-Bosch process faces significant challenges due to the intrinsic constraints of scaling relations in heterogeneous catalysis. Herein, we reported an approach of bending the "seesaw effect" to regulate the scaling relations over a tailored α-Fe metallic material (α-Fe-110s), realizing highly efficient light-driven thermal catalytic ammonia synthesis with a rate of 1260 μmol gcatalyst -1 h-1 without additional heating. Specifically, the thermal catalytic activity of α-Fe-110s was significantly enhanced by the novel stepped {110} surface, exhibiting a 3.8-fold increase compared to the commercial fused-iron catalyst with promoters at 350 °C. The photo-induced hot electron transfer further accelerates the dinitrogen dissociation and hydrogenation simultaneously, effectively overcoming the limitation of scaling relation over identical sites. Consequently, the ammonia production rate of α-Fe-110s was further enhanced by 30 times at the same temperature with irradiation. This work designs an efficient and sustainable system for ammonia synthesis and provides a novel approach for regulating the scaling relations in heterogeneous catalysis.

Self-driving photothermal anode electrocatalyst towards the robust OER for water electrolysis

The hydrogen production of water electrolysis is a potential technique route of clean energy exchange, but suffering from the sluggish oxygen evolution reaction (OER) owing to its four-electron step. In this work, we presented a significant improvement in the OER activity by photothermally triggering P-doped NiFe2O4 (NFO–P) electrocatalyst. As compared to the NiFe2O4 (NFO) catalyst, the excellent PEC performance of robust NFO–P is a result of more readliy generated active sites (Ni(III)), evidencing by the in-situ Raman spectra and polarization curves. With the near-infrared (λ = 808 nm) irradiation, the NFO–P surface temperature increases from 37 to 73 °C, and the NFO–P delivers a current density of 10 mA cm−2 at a pretty low overpotential of 191 mV (10 W/cm2), outperforms most OER catalysts including noble oxides. Photothermal enhancement in OER is attributed to photogenerated hot carriers and thermal activation. The thermal effect accelerates the kinetics, while with the assistance of the hot carrier, the rate-determining step (RDS) transforms from the O* to OOH* formation, reducing the activation energy. This study offers a thorough understanding of the combined contributions of hot carriers and thermal effects to the OER and also opens avenues for enhancing electrochemical efficiency and diminishing techno-economic costs in future applications.

Unveiling the secrets of non-evaporable getter films: Activation temperature, activation time, and achievable activation degree

Non-evaporable getter films play an important role in the creating and maintaining of high or ultra-high vacuum environments in advanced scientific disciplines. Prior to application, thermal activation in a vacuum environment is essential. Despite numerous attempts to reduce the film activation temperature, uncertainty remains as to whether extending the activation time at a relatively lower activation temperature will ensure a fully-activated state of the film. To address this issue, the microstructure and activation performance of the film has been investigated. Techniques, such as scanning electron microscopy, grazing incidence X-ray diffraction, energy dispersive spectroscopy, and in-situ X-ray photoelectron spectroscopy were employed. Experimental investigations show that a fully-activated state of the film cannot be achieved at around 150°C, regardless of the activation time. Further analysis shows that, at activation temperatures below about 200°C, the migration trend of oxygen atoms within TiZrV/TiZrHfV films exhibits asynchronous features. This process was accompanied by boundary effects of foreign atom migration channels. In addition, the achievable activation degree of the film shows a step characteristic. These results improve the understanding of the relationship between activation temperature, activation time, and the achievable activation degree of the film.