Chemistry and Materials Science

Abstract: EPR measurements on Fe- and Mn-doped SiCN samples, annealed at various temperatures, revealed that they were superparamagnetic. As well, their EPR spectra depended significantly on the sizes of the nanoparticles. The magnetism of SiCN/Fe is due mainly to the presence of Fe5Si3 and α-Fe superparamagnetic nanoparticles, distributed within the SiCN matrix. On the other hand, the main source of magnetism in SiCN/Mn ceramics is the presence of Mn₅Si₃C_x and α-Mn nanoparticles. The magnetization measurements on SiCN/Fe reveal that the difference between the ZFC (zero-field cooling) and FC (field cooling) magnetizations decreased with increasing annealing temperatures of the samples, implying that the homogeneity in the distribution of the sizes of nanoparticles increased with increasing annealing temperature. This result can be exploited for practical applications of Fe-doped SiCN nanoceramics as functional materials by annealing these samples at temperatures even higher than 1400 °C. The magnetization and EPR studies of Mn-doped SiCN ceramic indicate the presence of a variety of Mn-containing nanocrystallites, mainly ferromagnetic Mn₅Si₃C_x nanoparticles. There is also the possibility of presence of ferromagnetic Mn₅Si₃ nanoparticles with a rather high Curie temperature. The EPR spectra reveal that both Fe- and Mn-doped SiCN nanoparticles exhibit superparamagnetism, or single domain ferromagnetism, depending on their average sizes. They are thus potentially useful in being developed as high-temperature magnetic sensor devices due to SiCN being very stable to temperature variations, and being suitable functional materials for applications to electronics, spintronics and tunable soft magnetics for MEMS/NEMS (micro/nanoelectromechanical systems) devices, requiring homogeneous and uniform material.

Abstract: Stainless steel is widely used in biomedical and implant-related applications, but cor-rosion in physiologically relevant media can limit its long-term performance. In this study, ZnO-containing chitosan/gelatin composite coatings were fabricated on stain-less steel by electrophoretic deposition from stable water–ethanol suspensions. The coating-forming particles were obtained through chitosan/gelatin complexation in the presence of ZnO nanoparticles, enabling incorporation of an inorganic functional phase into a biopolymer matrix. The water–ethanol medium was used to suppress parasitic water electrolysis and promote the formation of continuous coatings. Sus-pension stability and electrophoretic behavior were evaluated by dynamic light scat-tering and zeta-potential measurements, while coating morphology and elemental composition were examined by scanning electron microscopy and energy-dispersive X-ray analysis. X-ray photoelectron spectroscopy was applied after 60 days of immer-sion in phosphate-buffered saline at pH 7.0 to assess the surface chemical state. Corro-sion behavior was followed by polarization resistance measurements over the same period. The ZnO-containing coating showed higher polarization resistance than both bare stainless steel and the ZnO-free chitosan/gelatin coating. The improved protection is attributed to the combined barrier effect of the biopolymer coating and the presence of ZnO within the deposited layer.

Abstract: The study investigates the effects of high-energy laser treatment on titanium-based alloys, TiAlV, TiNbZr, and TiNbSnTa, materials of high interest for medical applications such as implants and dental devices due to their exceptional strength-to-weight ratio, corrosion resistance, and biocompatibility. In this research, a unique high-energy laser was used for Ti-based surface activation. The laser exposure induced significant changes in both surface morphology and chemistry while preserving the bulk properties of the substrate. The modified surfaces were evaluated for their impact on cyto-compatibility and antibacterial activity. It was found that viability of U-2 OS cells incubated with laser-treated Ti-based substrates was not negatively affected and was comparable or slightly enhanced than that of control samples, indicating very good cytocompatibility of the prepared materials. Further, antibacterial evaluation against E. coli and S. epidermidis demonstrated that laser-treated samples had improved activity, especially against S. epidermidis, relative to untreated controls. Thus, these results demonstrate that high-energy laser treatment can simultaneously enhance biocompatibility and antibacterial properties of titanium alloys, highlighting its potential as a versatile surface modification strategy for advanced biomedical devices.

Abstract: This study investigated the effects of incorporating a novel amino acid compound (CM) into a reductive hair-straightening formulation on hair shape stability, mechanical properties, and surface characteristics. Hair trees from Brazilian donors were treated with a cysteamine-based straightening system, with or without CM, and evaluated under high-temperature, high-humidity conditions (40 °C, 75% relative humidity). CM-treated hair remained straight after 24 h of humidity exposure, whereas the control group exhibited partial or complete loss of the straightening effect. The mean hair spread width significantly decreased in the CM-treated group, indicating improved macroscopic shape stability. Mechanical analysis revealed a significant increase in bending rigidity (p < 0.05), whereas torsional rigidity and torsional hysteresis were significantly decreased (p < 0.01), suggesting direction-dependent changes in fiber mechanics. Furthermore, the coefficient of friction was significantly reduced following CM treatment, and the combing resistance tended to decrease. Scanning electron microscopy images revealed suppression of cuticle deterioration induced by repeated thermal and mechanical stress. Collectively, reduced torsion, improved shape retention, increased bending stiffness, and decreased fiber–fiber friction contributed to the improved combability and enhanced durability of straightening performance. Overall, CM enhanced humidity-resistant straightening while improving the surface and mechanical properties of the hair fibers. These findings suggest that CM is a promising additive for the development of humidity-resistant hair-straightening formulations.

Abstract: The photocatalytic conversion of CO₂ into multi-carbon (C₂+) fuels provides a sustainable route for carbon utilization but is often limited by poor charge separation, inefficient CO₂ activation, and sluggish carbon–carbon coupling. Herein, a vacancy-regulated Fe–Cu dual single-atom covalent organic framework/graphitic carbon nitride (COF/g-C₃N₄) S-scheme heterostructure was rationally designed and synthesized to enhance solar-driven artificial photosynthesis. Nitrogen-vacancy engineering generated abundant defect sites that improved visible-light harvesting and CO₂ adsorption, while atomically dispersed Fe–Cu dual sites embedded within the COF promoted efficient CO₂ activation and stabilized key *CO intermediates for C–C coupling. The intimate COF/g-C₃N₄ interface established an S-scheme heterojunction that facilitated directional charge transfer while preserving strong redox potentials. Comprehensive characterization using XRD, FESEM, TEM, HAADF-STEM, XPS, XANES/EXAFS, EPR, Raman spectroscopy, UV–Vis diffuse reflectance spectroscopy, photoluminescence spectroscopy, BET analysis, electrochemical impedance spectroscopy, and transient photocurrent measurements confirmed the successful formation of nitrogen vacancies, atomic Fe–Cu dispersion, and strong interfacial electronic coupling. The optimized heterostructure exhibited enhanced visible-light absorption with a narrowed band gap of approximately 2.18 eV, a 3.2-fold increase in photocurrent density, 61% lower charge-transfer resistance, and a 4.5-fold longer photoluminescence lifetime than pristine g-C₃N₄, indicating substantially improved charge separation. Under simulated AM 1.5G solar irradiation, the optimized catalyst achieved a total CO₂ reduction rate of ≈820 μmol g⁻¹ h⁻¹, with a C₂+ product selectivity of 83.6%, producing ethylene, ethanol, and acetate as the dominant products while maintaining over 93% of its initial activity after ten consecutive cycles. Density functional theory calculations revealed that nitrogen vacancies redistributed the electronic structure, Fe–Cu dual single-atom sites reduced the activation barrier for *CO dimerization, and the S-scheme interface promoted efficient charge migration, collectively accelerating carbon–carbon bond formation. This work demonstrates that integrating vacancy engineering, dual single-atom catalysis, and S-scheme heterojunction construction provides an effective strategy for highly selective solar-driven CO₂ conversion and offers new design principles for next-generation photocatalysts for artificial photosynthesis and renewable solar-fuel production.

Abstract: Combining the advantages of nickel cobalt sulfide and layered double hydroxide ex-hibits great potentials in designing of high-performance electrode materials for super-capacitors. Here, a representative nickel cobalt sulfide/layered double hydroxide het-erostructure has been deposited on carbon cloth to construct free-standing electrode for supercapacitor, marked as NCS@NCOH/CC. Benefited from the nanoporous struc-ture and ultrathin nanosheets, especially the enhanced electronic transfer kinetics due to heterostructure design, the electrode presents potential capacitive performance. Specifically, when increasing the current density from 1 to 20 A g-1, the DSC declines from 1339.1 to 1149.9 F g-1, corresponding to a retention of 85.9%, manifesting excep-tional rate performance. When charging and discharging under 10 A g-1 for 10,000 cy-cles, the DSC can maintain 71.3%, illustrating good cycle durability. Moreover, the fabricated NCS@NCOH/CC//AC/NF hybrid capacitor also demonstrates unique cyclic stability of 86.9% energy retention after 10,000 cycles under 5 A g-1. And an energy density of 20.52 Wh kg-1 at 1604.2 W kg-1 can be realized, corresponding to a tenfold increase compared with AC/NF//AC/NF symmetric capacitor. This work proves the feasibility of fabricating high performance transition metal sulfide@ hydroxide hetero-structure electrode by an electrodeposition method.

Abstract: The recyclability of entirely bio-based pots made from brewer's grains (BSG) and poly(butylene succinate) (PBS) in a weight ratio of 70:30, hereinafter referred to as MIXr, was evaluated. The resulting pots exhibited performance comparable to that of fos-sil-based plastics. The study aimed to determine the maximum percentage of recycled ma-terial that could be incorporated into virgin PBS (PBSv) while maintaining acceptable properties, thereby extending the material's life cycle through mechanical recycling before disposal via biodegradation or composting. For comparison, reference blends of virgin and recycled PBS (PBSv–PBSr) were prepared with identical compositions. The materials were characterized in terms of processability, tensile properties, thermal stability (TGA), chemi-cal group analysis (FTIR), and surface properties. The results showed that the presence of BSG significantly influences the recyclability of the biocomposite. While PBSv can contain up to 10 wt.% recycled PBS without significant losses in ductility or thermal stability, PBSv–MIXr blends exhibit reduced deformability (~20–30%) at MIXr contents between 2 and 20 wt.% and a reduction in thermal stability ranging between 16-22% at levels of in-corporation ranging between 10wt.% and 40 wt.%.

Abstract: SrAl₂O₄: Eu²⁺, Dy⁺³ polymeric composites are the reference photoluminescent materials in passive signaling due to their high emission intensity and long luminescent persistence. But their real long-term outdoor durability is still poorly understood. This study analyzes a strontium aluminate polymer composite exposed to real weathering for 15 years to evaluate its degradation threshold, exceeding the frameworks of accelerated tests. Using FTIR, Raman, FE-SEM, colorimetry and phosphorescence decay, the weathered material was compared with its reference material. Results show that the luminescent composite retains the structural properties, optical functionality improving its mechanical properties (increases the flexural strength between 23-64% and microhardness between 136-164%), suffering only a small yellowing suggesting a longer service life than expected. Finally, it was established that the loss in the optical performance is not due to irreversible degradation of the polymer or pigment but is caused by the accumulation of surface dust and the formation of an opaque outer layer. The application of a mechanical surface polishing removes this polluting layer, restoring optical transmittance and effectively recovering almost the original luminosity of the photoluminescent system.

Abstract: Metal–Organic Frameworks (MOFs) have undergone remarkable development in recent decades, transforming them into one of the most dynamic classes of emerging composite materials. These crystalline, porous coordination networks built from metal ions or metal clusters interconnected by organic linkers, form architectures with tunable porosity, large specific surface area, and chemical functionality. Due to their remarkable stability and customizable functionalities, the MOFs have attracted significant attention in recent years as promising materials for different applications. In 2025, Susumu Kitagawa, Omar Yaghi, and Richard Robson were awarded the Nobel Prize in Chemistry for pioneering the development of MOF crystalline materials with spacious internal cavities that can store, filter or catalyze molecules. This review systematically consolidates key developments since 2020 in the MOFs synthesis approaches, in their morphology and structures, luminescent properties and applications. The rapid yearly increase in MOFrelated publications, continuing strongly into 2026, reflects the growing global interest and highlights the rising importance of their design and applications. This trend motivates the central focus of this paper, which emphasizes the integrated use of MOFs in sensing, water treatment, and hydrogen storage. Finally, the future perspectives of MOF-based materials will be highlighted with the aim of providing guidelines for their further development and additional applications.

Abstract: Semi-transparent electrodes are a key enabling component for optoelectronic and photovoltaic architectures requiring light coupling through the top contact. Here, copper ultrathin films were deposited by thermal evaporation on glass substrates, systematically varying the thickness (40, 100 and 250 nm), and assessed through a combined structural, morphological, chemical and optoelectronic characterization. X-ray diffraction shows the formation of polycrystalline fcc Cu with the expected (111), (200), and (220) peaks, while scanning electron microscopy reveals compact, nanogranular morphologies whose continuity increases with homogeneity. X-ray photoelectron spectroscopy indicates the presence of surface oxidation/adsorbates in air-exposed films, highlighting the relevance of surface chemistry for contact engineering. Electrical measurements show a strong reduction of sheet resistance with thickness (from ∼30 Ω/□ at 40 nm to ∼0.5 Ω/□ at 250 nm), while optical transmittance in the visible decreases accordingly, making the thinnest film the most suitable compromise for semi-transparent operation. These results provide practical design guidelines and quantitative benchmarks for implementing evaporated copper as a cost-effective semi-transparent electrode in PV-related and general optoelectronic devices.

Abstract: This study aims to construct patterns with defined shapes on perfluoro ethylene propylene (FEP) via a replication process that has potential applications in tissue engineering. Our focus was on creating ripple periodic submicron-scale structures and subsequently activating them with argon plasma. Plasma activation of the replicated pattern on FEP substrates proved to be an effective, easy-to-execute and cost-efficient treatment method. Structured and activated carriers were prepared to study targeted cell growth in terms of cell adhesion and proliferation. Furthermore, the carriers were used to influence cell shape and the direction of the cell growth based on the properties of the pattern, primarily its morphology and dimensions. The carriers were seeded with human Wharton´s jelly stromal cells and their metabolic activity and morphology were studied using a resazurin assay and fluorescence staining of the actin cytoskeleton and cell nuclei. We found that plasma treatment improves cell colonization of the material more effectively than patterning the material with submicron-scale grooves (approximately 500 nm wide). However, this patterning enhances the susceptibility of the material to plasma modification, as evidenced by the subsequent improvement in the cell colonization.

Abstract: 1,2-Dichloroethane was found to stabilize the lattice of chloride anions associated with the protonated porphyrin of formula [C₄₄H₃₂N₄]Cl₂ 4C₂H₄Cl₂. The synthesis and X-ray characterization of this compound are reported and compared with analogous solvates. The porphyrin macrocycle displays a distorted saddle conformation, with chloride anions positioned above and below the mean plane of the ring, further surrounded by two dichloroethane molecules that stabilize the crystal packing. Second Harmonic Generation response was evaluated using the Kurtz−Perry powder technique with a ND:YAG laser (1064 nm).

Abstract: Electrochemically induced stress and strain energy are key factors governing mechanical degradation in battery electrodes during repeated ion insertion and extraction. However, their quantitative evaluation remains challenging. In this work, we present theoretical frameworks for describing the evolution of stress, strain energy, and elastic modulus in battery electrodes during electrochemical cycling. First, we discuss the general concepts of chemical strain, stress, and strain energy developed in substrate-bonded thin-film electrodes during ion insertion under the assumptions of elasticity and small deformation. Second, we present a general framework for estimating the apparent Young’s modulus of porous composite electrodes, which also enables inverse identification of the Young’s modulus of active materials when the apparent Young’s modulus of the porous composite electrode is experimentally available. Then, frameworks for estimating mechanical work and elastic strain energy of a substrate-constrained electrode during ion insertion with concentration-dependent thickness and modulus are discussed. Finally, we present inverse chemo-mechanical frameworks for diffusion-induced stress and concentration-dependent modulus in substrate-constrained electrodes under single-step galvanostatic ion insertion/extraction and galvanostatic insertion–extraction cycling. When combined with experimental measurements, these frameworks provide quantitative methods for understanding the evolution of stress, modulus, and strain energy in practical battery electrodes and offer guidance for the mechanical design of high-performance electrode materials.

Abstract: Rice husk–derived biochars produced at 550 °C and 700 °C were evaluated for methylene blue adsorption from aqueous solutions using a full factorial experimental design. The effects of pH (7–9), initial dye concentration (25–75 mg L-1), and adsorbent mass (0.05–0.15 g) and their interactions were systematically analyzed. Initial concentration and adsorbent mass were the most significant factors, followed by the pH–concentration interaction. Equilibrium time depended strongly on operating conditions and biochar type. For RH550, equilibrium times were 6 h at the central point and 8 h under conditions maximizing adsorption capacity. For RH700, equilibrium was reached in 6 h at the central point and reduced to 2 h under optimal conditions, indicating improved kinetics at higher pyrolysis temperature. Isotherm modeling indicated that Toth and Redlich–Peterson models best described the system, suggesting heterogeneous adsorption with mixed mono- and multilayer behavior. However, the Toth model overestimated adsorption capacity (70.8 mg g-1), whereas the Langmuir model provided a more realistic value (28.1 mg g-1), consistent with monolayer adsorption assumptions. Overall, rice husk biochars show strong potential as low-cost adsorbents for dye removal in aqueous systems.

Abstract: Thermal treatment of clay minerals induces a sequence of dehydration, dehydroxylation, and recrystallization reactions that control the properties of ceramic materials, calcined clays, and other high-temperature products. This review examines how vibrational spectroscopic techniques, particularly Fourier-transform infrared (FTIR), Raman, and infrared emission spectroscopy (IES), have advanced the molecular-level understanding of these transformations. Unlike conventional thermal analysis methods, these techniques directly monitor changes in hydroxyl groups, interlayer water, silicate frameworks, and newly formed phases during heating, providing real-time insight into reaction pathways and intermediate structures. The thermal behavior of major clay mineral groups, including kaolinite-group minerals, serpentines, smectites, illite, palygorskite, sepiolite, and mixed-layer clays, is compared in terms of their characteristic spectroscopic responses to increasing temperature. Particular attention is given to band shifts, intensity variations, band disappearance, and the appearance of new vibrational features associated with structural reorganization and phase development. The reviewed studies demonstrate that thermal stability is primarily governed by octahedral composition, cation–OH bond strength, vacancy distribution, and crystallinity. Integration of spectroscopic observations with complementary diffraction and thermal analysis data provides a unified framework for understanding clay mineral transformations and for optimizing thermal processing in ceramic manufacture and calcined clay applications.

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The use of the thermoelectric effect is a sustainable form of energy generation, as it allows waste heat to be harnessed to produce electrical energy. This study contributes to the replacement of the expensive and geopolitically risky metals currently used on an industrial scale with inexpensive and more environmentally friendly polymer-based composites. Composites based on singlewalled carbon nanotubes (SWCNTs) are being investigated, in which the polymer - here thermoplastic polyurethane (TPU) - modifies the thermoelectric properties of the SWCNTs. Three different types of TPU were selected by the Shore hardness, and the composition of the soft segments. The quantitative characterization of the TPU composition was performed using Infrared spectroscopy (IR). This allowed the urethane, ester, and ether content to be determined. SWCNT contents ranging from 1 to 5 wt% were incorporated into the TPU grades via melt-mixing. It can be shown that an increasing proportion of urethane groups in the TPU leads to a reduction in the Seebeck coefficient from around 40 µV·K^-1 up to 10 µV·K^-1, which indicates an n-type doping effect. Furthermore, it has been shown that the contents of ether and ester groups have a minor effect on thermoelectric properties. A power factor of 0.1 µW·m^-1·K^-2 could be achieved.

Abstract: Developing efficient and stable oxygen evolution reaction (OER) electrocatalysts is crucial to the practical application of water electrolysis for hydrogen production. Herein, tubular array of mesoporous NiMoO₄@NiFeS heterostructure was anchored on nickel foam through successive hydrothermal processing, liquid etching and direct sulfur vulcanization. The efficient charge transfer, phase transition and full exposure of active sites at the heterostructure’s interfaces as well as its superhydrophilic surface, engender NiMoO₄@NiFeS a highly effective OER electrocatalyst. A series of electrochemical experiments indicate that in 1.0 mol·L^-1 KOH NiMoO₄@NiFeS delivers overpotentials as low as 180 and 223 mV at current densities of 10 and 100 mA cm^-2, respectively, and that a Tafel slope merely 25.9 mV dec^-1 is achieved on NiMoO₄@NiFeS, evidencing that the tubular array of mesoporous NiMoO₄@NiFeS heterostructure significantly facilitates the interfacial transfer of charge/mass and the decrease in the energy barrier of the rate-determining step. This work provides valuable insights for the construction of efficient and low-cost electrocatalyst with hierarchical mesoporous core-shell structures.

Abstract: Highly filled magnetic filaments require binder systems that balance powder loading, melt flow, filament strength, and strand stability during material extrusion (MEX). Here, a polyolefin-based binder composed of a thermoplastic elastomer and grafted polyolefin (TPE + gPO) was used to prepare SmFeN- and SrFe12O19-based magnetic filaments. The feedstocks were compounded, extruded into 2.85 mm filaments using a single-screw extrusion line with automatic spooling, and printed by MEX into ring-shaped specimens. Thermogravimetric analysis confirmed high powder contents, with residual masses of approximately 89 wt.% for SmFeN and 85 wt.% for SrFe12O19. The filaments showed good dimensional control, with a diameter of 2.85 ± 0.07 mm and ovality <= 0.017 mm. Small-amplitude oscillatory rheology at 200-240 °C showed pronounced shear-thinning behavior and an elastic-dominant response (G’ > G’’) over 0.01-100 Hz, supporting flow through the nozzle and shape retention after deposition. Mechanical testing confirmed sufficient handling performance, with maximum flexural stress of 36.1 ± 0.1 MPa for SrFe12O19 and flexural modulus up to 5.5 ± 0.2 GPa for SmFeN. The results demonstrate that the TPE + gPO binder provides a suitable processing window for highly filled magnetic filaments for MEX-printed bonded magnets.

Abstract: This study demonstrates the rapid microwave-assisted upcycling of diverse bio-wastes — including aloe vera industrial leaf waste, corn cob agricultural residues, and soft slaughterhouse by-products (pork liver, lung, and heart) into high-surface-area activated carbons for efficient hexavalent chromium removal. To process the challenging high-moisture animal organs, a hybrid approach combining microwave-assisted hydrothermal pre-treatment with subsequent ZnCl₂-activated microwave pyrolysis was developed. Structural characterization by N₂ porosimetry, FT-IR, Raman and XRD confirmed the formation of stable, amorphous porous networks, with surface development strongly dependent on both precursor type and pyrolysis temperature. The prepared carbons exhibited excellent water dispersibility and long-term colloidal stability. Cr(VI) adsorption studies followed the Langmuir model, with thermodynamic analysis confirming spontaneous and endothermic uptake. Agricultural-derived carbons outperformed slaughterhouse-derived ones in terms of surface area and adsorption capacity, while all materials remained highly competitive with reported adsorbents in literature. These findings highlight a sustainable circular economy approach for converting animal by-products and biomass wastes into effective environmental adsorbents.

Abstract: Nanoplastics (NPs) in drinking water should be interpreted as the downstream analytical endpoint of a broader continuum of aquatic plastic pollution rather than as an isolated problem. Their detection remains analytically immature because environmentally relevant concentrations are low, particle chemistries are heterogeneous, natural colloids and treatment residuals interfere with measurement, and no single method can simultaneously resolve size, morphology, polymer identity, and mass concentration. Unlike occurrence-centered reviews, this PRISMA-guided review treats drinking-water nanoplastics as a metrological and molecular-identification problem in which preprocessing, particle-level confirmation, polymer-specific quantification, and uncertainty reporting must be integrated. A formal search was closed on 11 April 2026 using prespecified query families across publicly accessible scholarly records and backward citation chaining; 33 unique records were screened, 25 full texts were assessed, and 22 studies were included in the qualitative synthesis. Current evidence indicates that conventional FTIR and routine Raman workflows are inadequate for true nanoscale analysis, whereas advanced Raman-based approaches, AFM-IR, optical photothermal infrared spectroscopy, surface-enhanced Raman spectroscopy, and pyrolysis-gas chromatography-mass spectrometry offer complementary strengths but still have major limitations in throughput, particle-level information, or quantification. The main conclusion is that current uncertainty reflects unresolved analytical chemistry and metrological constraints as much as environmental variability. Regulatory progress will depend on orthogonal workflows, contamination-controlled preprocessing, validated reference materials, LOD/LOQ reporting, and interlaboratory harmonization.