Composite Formation Research Articles

Ensemble Machine Learning for Predictive Accuracy and Experimental Corroboration on transition metal-based electrodes for Supercapacitor

Machine learning (ML) proves highly effective in refining the electrochemical performance of electrode materials through precise tuning of compositional parameters. This study employs a data-driven ensemble learning approach, integrating classification and regression techniques to investigate the electrochemical behavior of transition metal-based electrodes with varying Ni:Co stoichiometry. A resample filter is introduced to the dataset to enhance predictive accuracy, yielding closely aligned classification and regression predictions. ML predictions discern that Ni-rich electrodes are apt for high-capacity, while Co-rich excels in high-rate applications. The characterizations of developed electrode materials XRD, FT-IR, EDS, and XPS confirmed the formation of desired compositions. The XPS analysis indicates that nickel and cobalt are in variable Ni2+/Ni3+ and Co2+/Co3+ oxidation states, enabling a reversible charge storage mechanism, while phosphorus is present in the pentavalent state. The TEM micrograph suggests that the nanoparticle size is extremely small, in the range of 1-3 nm, which is significant for providing a high surface-to-volume ratio, thereby enhancing specific capacitance (Csp). Experimental findings highlight N1C2 as the superior electrode, exhibiting impressive capacitance (2247.6 F g−1 at 3 A g−1), robust rate retention (78.6% from 3 to 20 A g−1), and substantial capacitance retention (91.3% after 10,000 charge-discharge cycles), which is in line with ML prediction. The experimental validation highlights the excellent agreement (percentage error: 2.48 to 8.46%) between the capacitance that was predicted, and the capacitance achieved experimentally. Predicted rate and cyclic retention curves align closely with experimental results, with minimal errors (0.03 to 19.3% and 3.95 to 19.64%, respectively). Lastly, the introduction of reverse structural and operational feature engineering contributes to the optimization of electrode material performance.

Unlocking the Potential of Ti3C2Tx MXene: Present Trends and Future Developments of Gas Sensing

In recent years, the need for future developments in sensor technology has arisen out of the changing landscape, such as pollution monitoring, industrial safety, and healthcare. MXenes, a 2D class of transition metal carbides, nitrides, and carbonitrides, have emerged as a particularly promising group in part due to their exceptionally high conductivity, large area, and tunable surface chemistry. Proposed future research directions, including material modification and novel sensor designs, are presented to maximize Ti3C2Tx MXene-based sensors for various gas sensing applications. While recent progress in Ti3C2Tx MXene-based gas sensors is reviewed, we consolidate their material properties, fabrication strategy, and sensing mechanisms. Further, the significant progress on the synthesis and applications of Ti3C2Tx MXene-based gas sensors, as well as the innovative technologies developed, will be discussed in detail. Interestingly, the high sensitivity, selectivity, and quick response times identified in recent studies are discussed, with specificity and composite formation highlighted to have a significant influence on sensor performance. In addition, this review highlights the limitations witnessed in real-life implementability, including stability, the possibility of achieving reproducible results, and interaction with currently available technologies. Prospects for further work are considered, emphasizing increased production scale, new techniques for synthesis, and new application areas for Ti3C2Tx MXenes, including electronic nose and environmental sensing. Contemplating the existing works, further directions and the development framework for Ti3C2Tx MXene-based gas sensors are discussed.

Effect of Fe doping on structural, optical and magnetic properties of CdS quantum dots

Abstract Pure CdS nanoparticles and Fe-doped CdS quantum dots (Cd₁₋ₓFeₓS, where x = 0.0, 0.03, 0.06, 0.09, and 0.12) were successfully synthesized using the co-precipitation method. X-ray diffraction (XRD) analysis confirmed the cubic phase structure of CdS without additional peaks, indicating the effective incorporation of Fe ions into the CdS lattice. The crystallite size exhibited a gradual increase with increasing Fe content. High-resolution transmission electron microscopy (HR-TEM) revealed a well-defined spherical morphology for pure CdS, while Fe doping induced notable agglomeration in the quantum dots. X-ray photoelectron spectroscopy (XPS) confirmed the formation of the CdFeS composition and provided insights into the valence states of Cd, Fe, and S. UV-Vis diffuse reflectance spectroscopy (DRS) demonstrated a decrease in the optical band gap from 2.29 eV to 2.18 eV with Fe doping, indicating a modification of the electronic structure. Magnetization studies revealed a transition from diamagnetic behavior in pure CdS to ferromagnetic behavior in Fe-doped samples. Additionally, Fe doping significantly influenced the magnetic parameters, including saturation magnetization, remanence, and coercivity. These results highlight the structural, optical, and magnetic properties of CdS can be tuned through Fe doping, making these materials promising candidates for optoelectronic and spintronic applications.
Keywords: CdS quantum dots, XRD, XPS, optical energy gap, ferromagnetism.

Monolayer MoS2 with S vacancy defects doped with Group V non-metallic elements (N, P, As): a first-principles study.

This study systematically investigated the effects of single S-atom vacancy defects and composite defects (vacancy combined with doping) on the properties of MoS2 using density functional theory. The results revealed that N-doped S-vacancy MoS2 has the smallest composite defect formation energy, indicating its highest stability. Doping maintained the direct band gap characteristic, with shifts in the valence band top. The Fermi level slightly shifted down in N- and P-doped systems, with N-doped MoS2 showing a larger increase in valence band top energy. Doping also significantly altered the density of states at the Fermi level and weakened the dielectric properties of MoS2. The maximum dielectric peaks of doped systems appeared near 2.7 eV with reduced intensities and red-shifted energies. Optical properties were significantly changed, with decreased reflectance, narrower reflectance spectra, and blue-shifted absorption spectra. These findings suggest that introducing composite defects can effectively reduce the forbidden bandwidth of MoS2, enhancing electrical conductivity. This research provides theoretical guidance for novel material design and offers insights into composite defect behavior in other two-dimensional materials. The Materials-Studio CASTEP module was used to calculate density functional theory (DFT). A plane wave ultrasoft pseudopotential is used to optimize the crystal structure, and the generalized gradient approximation (GGA) in the form of Perdew-Burke-Ernzerhof (PBE) is used to characterize the exchange correlation energy. After the convergence test, the truncation energy and dot settings were finally selected to be 450 eV and 3 × 3 × 1, respectively, the convergence accuracy was set to 1.0e-5eV/atom, and the convergence criterion for the interatomic interaction force was 0.02 eV/Å. The parameters were all at or better than the accuracy settings. The vacuum layer between the layers wasset to 18 Å to avoid interactions caused by the periodic calculation method.

Review of Layered Transition Metal Oxide Materials for Cathodes in Sodium-Ion Batteries

The growing interest in sodium-ion batteries (SIBs) is driven by scarcity and the rising costs of lithium, coupled with the urgent need for scalable and sustainable energy storage solutions. Among various cathode materials, layered transition metal oxides have emerged as promising candidates due to their structural similarity to lithium-ion battery (LIB) counterparts and their potential to deliver high energy density at reduced costs. However, significant challenges remain, including limited capacity at high charge/discharge rates and structural instability during extended cycling. Addressing these issues is critical for advancing SIB technology toward industrial applications, particularly for large-scale energy storage systems. This review provides a comprehensive analysis of layered sodium transition metal oxides, focusing on their structural properties, electrochemical performance, and degradation mechanisms. Special attention is given to the intrinsic and extrinsic factors contributing to their instability, such as structural phase transitions, and cationic/anionic redox behavior. Additionally, recent advancements in material design strategies, including doping, surface modifications, and composite formation, are discussed to highlight the progress toward enhancing the stability and performance of these materials. This work aims to bridge the knowledge gaps and inspire further innovations in the development of high-performance cathodes for sodium-ion batteries.

Enhancing the Photocatalytic Efficacy of g-C3N4 Through Irradiation Modification and Composite Construction with Ti3C2 for Photodynamic Therapy

Photodynamic therapy (PDT) holds considerable promise for advancing anticancer treatment, owing to its precision and minimally invasive nature. In this study, we successfully synthesized a series of titanium carbide (Ti3C2, TC)/graphitic carbon nitride (g-C3N4, CN) nanocomposite through a synergistic approach combining electron beam irradiation and 2D/2D composite formation. According to the results, 1TC/200-CN (1TC, which TC was 1, referred to the mass ratio; 200-CN, which CN was 200 kGy, referred to the irradiation metering) displayed a 94% degradation rate of methylene blue (10 mg/L) in 100 min. Furthermore, the proliferation rate of CAL-27 cells was suppressed to just 23.3% at a concentration of 320 μg/mL of 1TC/200-CN. Notably, the group treated with this concentration exhibited the largest residual scratch area, accompanied by a notable decrease in mitochondrial membrane potential. These enhanced effects were attributed to the efficient transfer of electron-hole pairs facilitated by the TC/CN composite. Our findings not only contribute to the development of efficient and stable nanocomposites for PDT applications but also provide valuable insights into the utilization of nanomaterials in the biomedical field, thereby paving the way for potential breakthroughs in cancer treatment.

PH-Triggered Phase Transitions, Coexposure of (001) and (110) Facets, and Oxygen Vacancies in BiOCl Photocatalysts.

Bismuth oxychloride (BiOCl) is known for its unique layered microstructure, which plays a pivotal role in enhancing its photocatalytic properties. This study introduces a novel strategy for controlling the phase composition, facet orientation, and oxygen vacancy formation in BiOCl through precise pH adjustment during the synthesis. By employing a hydrothermal method, we systematically varied the pH to produce distinct BiOCl phases and conducted detailed structural and photocatalytic analyses. Remarkably, BiOCl synthesized at pH = 7 demonstrated superior photocatalytic activity on rhodamine B (RhB) degradation, which can be attributed to the coexposure of the (001) and (110) facets, as well as an increased concentration of oxygen vacancies. Density functional theory study also revealed that a high concentration of oxygen vacancies leads to enhanced charge separation, which is beneficial for photocatalytic activity. These results indicate that optimizing the pH during synthesis is a viable approach to enhancing the photocatalytic efficiency of BiOCl, offering significant potential for advanced applications in environmental remediation and solar energy conversion.

BiVO4-Based Systems Magnetron Sputtered with Silver Nanoparticles for the Artificial Photosynthesis Reaction

The incorporation of Ag nanoparticles onto BiVO4 (a known H2O oxidising photocatalyst) through magnetron sputtering to form a composite was studied. ICP-OES results showed that the loading of Ag on BiVO4 was below 1% in all cases. UV-Vis DRS and CO2-TPD analyses demonstrated that upon incorporation of Ag onto BiVO4, an increase in the extent of visible light absorption and CO2 adsorption was seen. TEM imaging showed the presence of Ag particles on the surface of larger BiVO4 particles, while XRD analysis provided evidence for some doping of Ag into BiVO4 lattices. The effect of the composite formation on the activity of the materials in the artificial photosynthesis reaction was significant. BiVO4 alone produces negligible amounts of gaseous products. However, the Ag-sputtered composites produce both CO and CH4, with a higher loading of Ag leading to higher levels of product formation. This reactivity is ascribed to the generation of a heterojunction in the composite material. It is suggested that the generation of holes in BiVO4 following photon absorption is used to provide protons (from H2O oxidation), and the decay of an SPR response on the Ag NPs provides hot electrons, which together with the protons reduce CO2 to produce CH4, CO, and adsorbed hydrocarbonaceous species.

Effect of the Ti2CT x (T x = O, OH, and H) Functionalization on the Formation of (TiO2)5/Ti2CT x Composites.

First-principles density functional theory calculations are carried out on the (TiO2)5 cluster supported on the Ti2CT x (0001) surface with different chemical terminations, i.e., -H, -O, and -OH, to study the interaction and understand the Ti2CT x functionalization effect on the formation of (TiO2)5/Ti2CT x composites. Results show an exothermic interaction for all cases, whose strength is driven by the surface termination, promoting weaker bonds when the MXene is functionalized with H atoms. For Ti2CH2 and Ti2C(OH)2 MXenes, the interaction is accompanied by a charge transfer towards the titania cluster. All adsorptions are accompanied by a significant structural deformation of the titania nanocluster. The analysis of the density of states of (TiO2)5/Ti2CH2 and (TiO2)5/Ti2C(OH)2 composites shows a clear almost metallic character with titania-related states close to the Fermi level. However, for (TiO2)5/Ti2CO2, the band positions are similar to those of a Type-I heterojunction. Overall, the MXene surface termination influence on the TiO2/MXene interaction is unveiled, providing more stable composite formations when the MXene surface is functionalized with -H and -OH groups, where the adsorption process is accompanied by significant charge transfer.

Comparison of In Situ and Postsynthetic Formation of MOF-Carbon Composites as Electrocatalysts for the Alkaline Oxygen Evolution Reaction (OER).

Mixed-metal nickel-iron, NixFe materials draw attention as affordable earth-abundant electrocatalysts for the oxygen evolution reaction (OER). Here, nickel and mixed-metal nickel-iron metal-organic framework (MOF) composites with the carbon materials ketjenblack (KB) or carbon nanotubes (CNT) were synthesized in situ in a one-pot solvothermal reaction. As a direct comparison to these in situ synthesized composites, the neat MOFs were postsynthetically mixed by grinding with KB or CNT, to generate physical mixture composites. The in situ and postsynthetic MOF/carbon samples were comparatively tested as (pre-)catalysts for the OER, and most of them outperformed the RuO2 benchmark. Depending on the carbon material and metal ratio, the in situ or postsynthetic composites performed better, showing that the method to generate the composite can influence the OER activity. The best material Ni5Fe-CNT was synthesized in situ and achieved an overpotential (η) of 301 mV (RuO2η = 354 mV), a Tafel slope (b) of 58 mV/dec (RuO2b = 91 mV/dec), a charge transfer resistance (Rct) of 7 Ω (RuO2 Rct = 39 Ω), and a faradaic efficiency (FE) of 95% (RuO2 FE = 91%). Structural changes in the materials could be seen through a stability test in the alkaline electrolyte, and chronopotentiometry over 12 h showed that the derived electrocatalysts and RuO2 have good stability.

The role of light in regulating plant growth, development and sugar metabolism: a review.

Light provides the necessary energy for plant photosynthesis, which allows plants to produce organic matter and energy conversion, during plant growth and development. Light provides material energy to plants as the basis for cell division and differentiation, chlorophyll synthesis, tissue growth and stomatal movement, and light intensity, photoperiod, and light quality play important roles in these processes. There are several regulatory mechanisms involved in sugar metabolism in plants, and light, as one of the regulatory factors, affects cell wall composition, starch granules, sucrose synthesis, and vascular bundle formation. Similarly, sugar species and genes are affected in the context of light-regulated sugar metabolism. We searched the available databases and found that there are fewer relevant reviews. Therefore, this paper provides a summary of the effects of light on plant growth and development and sugar metabolism, further elaborates on the mechanisms of light effects on plants, and provides some new insights for a better understanding of how plant growth is regulated under different light conditions.

Investigation of the Synergistic Effect of Doping and Composite Formation on Electrochemical OER Performance of g-C3N4 for Sustainable Energy

Investigation of the Synergistic Effect of Doping and Composite Formation on Electrochemical OER Performance of g-C₃N₄ for Sustainable Energy

Recent Advances in the Tunable Optoelectromagnetic Properties of PEDOTs.

Conducting polymers represent a crucial class of functional materials with widespread applications in diverse fields. Among these, poly(3,4-ethylenedioxythiophene) (PEDOT) and its derivatives have garnered significant attention due to their distinctive optical, electronic, and magnetic properties, as well as their exceptional tunability. These properties often exhibit intricate interdependencies, manifesting as synergistic, concomitant, or antagonistic relationships. In optics, PEDOTs are renowned for their high transparency and unique photoelectric responses. From an electrical perspective, they display exceptional conductivity, thermoelectric, and piezoelectric performance, along with notable electrochemical activity and stability, enabling a wide array of electronic applications. In terms of magnetic properties, PEDOTs demonstrate outstanding electromagnetic shielding efficiency and microwave absorption capabilities. Moreover, these properties can be precisely tailored through molecular structure modifications, chemical doping, and composite formation to suit various application requirements. This review systematically examines the mechanisms underlying the optoelectromagnetic properties of PEDOTs, highlights their tunability, and outlines prospective research directions. By providing critical theoretical insights and technical references, this review aims to advance the application landscape of PEDOTs.

Construction of enzyme-MOFs composite with carbon dots: A strategy to enhance the activity and increase the growth rate of the enzyme-ZIF-8 composite.

Encapsulating enzymes in metal-organic frameworks (MOFs) enhances enzyme protection and improves the accuracy of inhibitor recognition and screening. Zeolitic imidazolate framework-8 (ZIF-8) has been widely used as a host matrix for enzyme immobilization. However, challenges such as the microporous structure and hydrophobicity of ZIF-8, along with the protonation of 2-methylimidazole, hinder the maintenance of activity and the rapid formation of composite. Herein, a new strategy to synthesize novel enzyme-MOFs composite by encapsulating carbon dots (CDs)-modified enzyme and Fe3O4 nanoparticles within ZIF-8 is presented for the first time. The contribution of CDs in enzyme-MOFs composite was investigated. Characterizations reveal that the CDs-modified enzymes compete with imidazole for Zn ions, inducing mesoporous structures that alleviate diffusion limitations. Modification of enzyme with CDs also modulates enzyme-MOFs interfacial interactions, accelerating the formation of composite. Activity evaluation shows that enzyme-MOFs composite (THR@CDs/Fe3O4@ZIF-8) retains 81.76% enzyme activity under harsh conditions and maintains 66.0% of the initial enzyme activity after 10 reuse cycles. This synthesis strategy for the novel enzyme-MOFs composite was proven to be universal. The Km value of THR@CDs/Fe3O4@ZIF-8 (19.32μM) is lower than that of THR/Fe3O4@ZIF-8, indicating that modification with CDs significantly increases the affinity of enzyme. Furthermore, THR@CDs/Fe3O4@ZIF-8 was effectively utilized for enzyme inhibitor recognition and screening. These results demonstrate that the proposed method is a universal approach for rapidly and controllably fabricating enzyme-ZIF-8 composite with elevated activity and exceptional stability, offering promising potential for advanced drug recognition and screening platforms.

Mechanical and Thermal Properties of Poly (Butylene Adipate-co-Terephthalate) / Poly (Lactic Acid) Blend and Montmorillonite Functionalized by Ionic Liquids Composites

The composites of poly (butylene adipate co-terephthalate) / poly (lactic acid) (PBAT/PLA) blend and montmorillonites functionalized using imidazole-derived ionic liquids with different carbon chain sizes (butyl, octyl, and dodecyl) proved to be a promising alternative for improving the thermal and mechanical properties of the polymer blend. Functionalization of montmorillonites by ionic liquids was confirmed by increasing the basal spacing, and spectroscopical and thermal analysis evidence. The composite synthesis was carried out by casting technique generating homogeneous polymeric films. X-ray diffraction analyses suggested that montmorillonite functionalization with the ionic liquid of the butyl carbon chain fostered exfoliation and incorporation of the clay into the polymer. Furthermore, an increase in the thermal stability and mechanical properties of the material was observed. The other composites formed between the PBAT/PLA blend and the montmorillonite functionalized by ionic liquids of higher carbonic chain showed micro composites formation. Thus, their thermal and mechanical properties had no significant improvements.

Origin of the formation of isostructural bcc-Fe+bcc-Cu nanocomposites in Fe–Cu alloy via vacuum co-deposition

This study examined the influence of substrate temperature and the ratio of iron and copper vapor flow on the structural state of Fe–Cu vacuum condensates. XRD patterns of the condensates deposited under specific electron beam physical vapor deposition process parameters revealed peaks corresponding to either bcc or bcc+fcc phases. Analysis of the lattice parameter of the single bcc structure indicates that only a portion of the copper atoms dissolve in the bcc-Fe lattice, while undissolved copper atoms form bcc-Cu inclusions that are coherent with the bcc-Fe lattice. A model for the formation of the bcc-Cu structure as an adaptive phase is proposed. The formation of the adaptive phase in vacuum condensates is driven by the bcc-Cu epitaxy on the surface of bcc-Fe crystallites and excess vacancies in the condensate structure. As the copper concentration in the isostructural Fe–Cu composite increases, the level of microstrain in its bcc crystal lattice also increases. The transformation of bcc-Cu particles into fcc-Cu via a shear mechanism occurs when heated above 400 °C. It was found that increasing the deposition temperature reduces the concentration range for the formation of the isostructural composite. It is suggested that higher deposition temperatures and increased copper concentration lead to larger copper particle sizes and reduced excess vacancy concentration, which disrupts their coherence with the bcc-Fe matrix. As a result, a composite with a eutectic-like microstructure consisting of bcc-Fe and fcc-Cu phases forms directly during vapor phase condensation.

Template‐Free Synthesis of Mesoporous Iron‐Nickel‐Cobalt Oxide Microspheres via Ultrasonic Spray Pyrolysis Across Temperature Gradients for Enhanced Visible Light Photocatalytic Activity

AbstractThis study explores the synthesis of template‐free mesoporous FeNiCo oxide microspheres through a direct and efficient ultrasonic spray pyrolysis (USP) technique. USP method includes precise control over particle size, the formation of mesoporous structures, multimetallic compositions, and high synthesis speed, all of which can contribute to enhanced photocatalytic activity. The analysis of the resulting microspheres involved a thorough exploration of their phase structure, texture, morphology, and photocatalytic properties. This investigation employed various analytical techniques, including X‐ray diffraction (XRD), Raman spectroscopy, field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), and nitrogen adsorption−desorption. The microspheres displayed a well‐crystallized cubic crystal structure, as evidenced by the X‐ray diffraction pattern, with a corresponding crystallite size ranging from 6.0 to 7.4 nm. The FESEM images revealed the synthesis of uniform‐sized particles with spherical shapes. N2 adsorption and desorption highlighted the mesoporous structure of FeNiCo oxide microspheres, indicating diverse surface areas and pore distributions, influencing catalytic performance and dye adsorption. The capability of the synthesized photocatalysts to degrade methylene blue was examined under both UV and visible light irradiation. The FeNiCo oxide microspheres exhibited a band gap of 2.34 eV. Photocatalytic evaluation revealed that the FeNiCo oxide nanoparticles achieved a 65% degradation of methylene blue within 110 min.

Synthesis of a Hierarchical FeBTC/FeS Structure with Enhanced Water Stability for Environmental Remediation

AbstractAn iron metal‐organic framework (MOF) was synthesized and tested for the photocatalytic degradation of organic dyes using methylene blue (MB) standard. The iron 1,3,5‐benzenetricarboxylate (BTC) MOF was synthesized using a simple and low‐cost electrochemical method, aligned with the green chemistry principles, 64% yield. FeBTC was modified in the presence of Na2S solutions (0.01 and 0.02 mmol L−1), giving FeBTC/FeS composites. SEM analysis showed the MOF structure preservation and the homogeneous dispersion of the sulfur on the composite surface. FeBTC MOF and FeBTC/FeS composites were characterized by XRD, FTIR, TGA, EDX, XPS, and EPR spectroscopy. The FeBTC MOF exhibited 25.1% of MB removal by adsorption (dark), whereas 43.4% (removal/degradation) was observed under simulated solar light. The modification with Na2S promoted the formation of composites containing iron polysulfide species, as observed by XPS. The FeBTC/FeS‐1 and FeBTC/FeS‐2 composites showed superior performance, achieving MB removal efficiencies of 86.0% and 82.4%, respectively, after an irradiation time of 120 min. Compared to photo‐Fenton processes, FeBTC and FeBTC/FeS‐1 composite demonstrated MB removal efficiencies of 96.9% and 99.6%, respectively. Thus, the FeBTC photocatalytic activity was increased by iron polysulfides formation on the MOF structure. FeBTC/FeS‐1 composite exhibited excellent adsorptive/photocatalytic activity, demonstrating its decolorizing potential for MB‐containing effluents.

Utilizing biomass-derived activated carbon hybrids for enhanced thermal conductivity and latent heat storage in form-stabilized composite PCMs

ABSTRACT In this study, the focus was on developing multifunctional organic form-stabilized composite phase change materials (PCMs) to efficiently manage thermal energy and promote sustainable energy utilization. The novel composite PCMs were designed and synthesized by incorporating Methyl stearate (MtS) as the PCM with pristine activated carbon derived from coconut shells (CAC) and thermally enhanced CAC@Graphene nanoplatelets (GnP) hybrid matrices. Particularly, the combination of CAC90@GnP10/MtS allowed the composite PCM to exhibit excellent thermophysical responses, capitalizing on the unique properties and synergistic effects of each component. The resulting composite PCM from this combination demonstrated remarkable performance, with a high loading ratio of 70% and a latent heat of 160.87 J/g, which is 27.52% higher than that of the pristine CAC-supported PCM. The test results indicated that the chemical and crystal structure of MtS remained unaffected after the composite formation. The thermal conductivity of CAC90@GnP10/MtS was found to be 102.85% higher than CAC/MtS and 195.83% higher than MtS alone. The enhancement in thermal conductivity was further validated through observed reductions in melting and solidification times, as well as analysis using infrared thermal imaging. In conclusion, the development of these intelligent, multifunctional composite PCMs, which utilize CAC@GnP hybrids as supporter scaffolds and thermal conductivity enhancers for MtS, holds great promise for effective sustainable energy usage and thermal energy management systems in various fields like waste heat utilization, energy-saving buildings, constant temperature protection, thermal management of electronic devices, aerospace industry, textiles, automotive, and renewable energy systems.

Geochemistry and formation conditions of the natural water composition in the nothern outskirts of Kazan

Kazan is located on the left bank of the Kuibyshev water reservoir in the east of the Russian Plain. The Blue Lakes, which are unique salt-water karst lakes in the Middle Volga region, appear to be a real natural treasure in the northern outskirts of the city. On the basis of field and analytical data obtained in 2023, the geochemical composition of the natural water is studied in the Blue Lakes, the Solonka and Kazanka rivers, uprising springs, and snow cover. Significant variations in the hydrochemical field are controlled by the effect of discharging relatively deep sulfate calcium groundwater from the lower Permian carbonate-sulfate deposits with a mineralization of about 2.5 g/l. The shares of these artesian waters in the river discharge have been determined. They are about 80% for the mouth of the Solonka River in the initial period of summer low water and about 50–60% for the lower reaches of the Kazanka River in the initial period of winter low water. Maximum values of deep water inflows are observed in river valleys along fracture zones of submeridional and northeastern orientation. The stability of hydrochemical parameters in the studied water bodies over time is shown, which is due to a high rate of water exchange and a low anthropogenic impact on the environment. Complexes of microcomponents concentrated in artesian and near-surface waters have been identified. In artesian waters such components are: Ca, Sr, Mg, Li, U, Re, Se; and in the near-surface – K, Fe, Mn, Ba, As, Co. It is noted that in order to determine the degree of surface water pollution, it is important to take into account the conditions of their composition formation and to distinguish between excess concentrations caused by natural and anthropogenic factors.