Abstract The increasing demand for high-performance and sustainable lithium-ion batteries has led to the exploration of alternative anode materials beyond traditional graphite. Hard carbon, a disordered form of carbon characterized by expanded interlayer spacing and a high density of defect sites, exhibits promising electrochemical properties, particularly under fast-charging and low-temperature operation conditions. In this study, waste polyethylene terephthalate (PET) was converted into hard carbon anodes through pyrolysis at two different temperatures: 1000 °C and 1500 °C. The objective was to examine how the thermal treatment affects the structural characteristics and lithium ion storage behavior of the materials. X-ray diffraction (XRD), Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), and transmission electron microscopy (TEM) analyses indicated that the lower-temperature (1000 °C) heat-treated PET-derived hard carbon (pHC-L) had a more disordered structure with larger interlayer spacing and a higher concentration of defects. In contrast, the higher-temperature (1500 °C) heat-treated sample PET-derived hard carbon (pHC-H) showed increased graphitic ordering and fewer surface-active sites. At 20 mA g-1, the hard carbon produced at the lower heat-treatment temperature delivered 186.94 mAh g-1, compared with 130.15 mAh g-1 for the higher-temperature product; this improvement is attributed to the larger interlayer spacing and higher defect/micropore population, which promote sloping-type lithium-ion adsorption and pore-filling. Meanwhile, pHC-H demonstrated better rate performance with reduced polarization and enhanced reversibility. Both electrodes displayed a gradual increase in capacity during cycling, indicating structural activation attributed to solid-electrolyte interphase stabilization and improved accessibility of the electrolyte. These findings indicate that waste PET-derived hard carbon can be effectively optimized through pyrolysis temperature to achieve a balance between capacity and rate capability. This presents a sustainable and versatile platform for anode materials in next-generation lithium-ion batteries.

Abstract Piezoelectric composite-based nanogenerators are attracting attention as self-powered sources for next-generation wearable and portable electronic devices. The performance of piezoelectric composites is highly dependent on the connectivity structure. Conventional 0–3 type composites, in which piezoelectric fillers are randomly dispersed within a polymer matrix, suffer from reduced piezoelectric performance due to inefficient stress transfer. This review paper systematically investigates research that has enhanced piezoelectric performance by strategically designing the connectivity structure of piezoelectric composites. The correlation between various connectivity patterns, such as 1–3, 2–2, 3–1, and 3–3 types, and the piezoelectric output performance is analyzed. In particular, the three-dimensionally interconnected 3–3 structure has been demonstrated to be effective in improving output performance by facilitating continuous pathways for mechanical stress transfer. Additionally, fabrication strategies for designing these structures using various manufacturing techniques are discussed. In conclusion, this paper suggests the potential applicability of these high-performance composites in fields such as self-powered sensors, biomedical devices, and wearable electronics.

Abstract Manganese-based cathode materials suffer from irreversible manganese dissolution during cycling, leading to rapid capacity decay and poor long-term stability. To address this issue, a zinc-alginate-polyacrylamide (ZAP) gel film is in-situ polymerized on the surface of Ni–Co co-doped δ -MnO 2 cathodes. The ZAP gel forms a tightly bonded three-dimensional network through Zn 2+ -alginate coordination, uniformly encapsulating the cathode surface. Meanwhile, hydrogen bonding between hydroxyl groups in the gel and MnO 2 combines with numerous tiny pores that facilitate redox reactions while inhibiting irreversible manganese leaching. Following ZAP gel coating, the cathode demonstrates improved long-term cycling performance, retaining a specific capacity of 165.0 mAh · g −1 after 4000 cycles with a capacity retention rate of 85.94%. This corresponds to increases of 70.80% in specific capacity and 91.57% in capacity retention compared to pristine δ -MnO 2 . The hydrogel coating approach offers a feasible modification direction for designing materials with enhanced cycling lifetimes.

Abstract Polyaniline and polyamide have electron-active sites, which make them one of the most attractive materials for the adsorption of Cr (VI) from aqueous media. Their adsorption capacity for Cr (VI) can be enhanced through modification and blending techniques. In this study, sulfonated polyaniline–nylon 6 (SPAN–Ny6) nanocomposites were synthesized via in-situ oxidative polymerization of aniline using ammonium persulfate as an initiator in a formic acid medium. Concentrated sulfuric acid was added dropwise in the presence of 15%, 30%, 50%, and 70% aniline relative to nylon 6. Then, these nanocomposites were identified and characterized using Fourier transform infrared spectroscopy, x-ray diffraction, and thermogravimetric analysis, and their morphology was studied by field emission scanning electron microscopy (FE-SEM). Conductivity of the prepared nanocomposites was also measured using the four-point method, and the highest measured conductivity was 0.248 S cm −1 for the SPAN-Ny6-70% nanocomposite. Additionally, the processability of the nanocomposites was studied by the electrospinning technique in formic acid as a solvent. Morphology of the nanofibers was identified by FE-SEM. The hydrophilicity of the nanofibers was investigated by contact angle analysis, which indicated a significant decrease in hydrophilicity of the nanocomposites with increasing percentage of polyaniline sulfonate. Subsequently, the synthesized nanocomposites were used to absorb the Cr (VI) contamination from aqueous solutions after optimizing the adsorption pH, time, temperature, and initial chromium ion concentration. The adsorption isotherm and kinetics were studied in optimized conditions, which revealed that the adsorption process was consistent with the Langmuir isotherm and pseudo-second-order kinetic model.

Abstract Minor changes in process variables, such as temperature, processing speed, and cooling rate, can significantly impact the properties of the final product in a sheet extrusion process. As a result, many optimization efforts focus on each of these variables. This study explored a machine learning-assisted process design for a polypropylene/carbon black composite sheet. The extrusion process parameters were selected as input variables, while tensile strength, void content, width, and thickness were measured, resulting in a dataset of 180 entries. A deep learning neural network was employed to identify and propose optimal combinations of process parameters and validate these proposals by comparing predicted values to experimental data. The polymer melt index had a significant effect on tensile strength, which is attributed to the degree of crystallinity. The process optimization led to a 20% increase in the tensile strength of continuous fiber composites, enhancing the matrix's toughness and improving interfacial load-carrying capacity.

Abstract Recently, there have been various threats using sharp tools such as knives, and anti-stab clothing and shields have been used to counter these threats. This study created a stab-resistant panel using a carbon fiber-reinforced plastic (CFRP) composite with lightweight and high-strength properties. Specifically, the panel was coated with a high-hardness layer using lacquer and plate-shaped alumina (Al2O3) particles for a bioinspired structure of abalone shells. The hardness allows for fewer layers of carbon fabric to reduce the weight of the panel. The coating layer was successfully bonded to the CFRP panels with epoxy to maintain a stable structure during the penetration of sharp tools. The stab-proof performance was evaluated using the National Institute of Justice standards' single-edged knife blade (P1). The P1 blade penetrated the panel 13.46 mm, but the high-hardness layer significantly reduced the penetration depth by 70.2% to 4.01 mm.

Abstract Wearable sensors based on the triboelectric effect have been developed as powerful tools for healthcare monitoring recently, enabling the acquisition of physiological signals. However, in the case of the pulse, the mechanical characteristics make it imperative due to the tiny pressure and low-frequency that the sensor measuring it be highly sensitive. This work focuses on designing a highly sensitive, diameter-tuned triboelectric pressure sensor (DPS) by controlling the applied voltage during P(VDF-TrFE) electrospinning, to achieve a higher triboelectric effect and thus greater sensitivity of the DPS. Specifically, by varying the applied voltage, we quantitatively compared changes in fiber diameter, β -phase fraction, and crystallinity. We present that higher electrospinning voltage yields thinner fibers with increased β -phase content and crystallinity, which enhance dielectric polarization and strengthen charge retention, thereby boosting the triboelectric effect. Consequently, the resulting high-sensitivity DPS precisely detects human pulse signals. The fabricated DPS achieved remarkable sensitivity (0.03044 nA · Pa −1 ) and a high coefficient of determination (∼99.7%), maintaining stable performance over 20 000 cycles. Reliable pulse waveforms can be detected at the carotid, radial, and brachial arteries, and validation against a commercial pulse sensor confirmed its accuracy of 97%. The DPS exhibits excellent sensitivity, durability, and validated applicability in human pulse monitoring, underscoring its potential for integration into next-generation wearable healthcare and self-powered physiological monitoring systems.

Abstract In this work, we have synthesised ZnO nanoparticles (Nps) with an average diameter of 9.5 nm via a soft chemical route. These ZnO Nps were encapsulated within a mesoporous SiO 2 matrix through a microemulsion-assisted sol–gel procedure to form ZnO@SiO 2 (ZS) composite. Then, silver Nps were successfully impregnated onto the SiO 2 matrix surface to form ZnO@SiO 2 @Ag (ZSAg) nanocomposite. Transmission electron micrographs and scanning electron microscope analysis confirmed that nano-sized Ag of size about 5 nm is homogeneously incorporated into the SiO 2 matrix, which formed a Schottky barrier in the structure and narrowed the band gap energy from 3.1 to 2.58 eV. The samples have been evaluated for photocatalytic degradation of methylene blue (MB) under irradiation of UV and sunlight. ZnO demonstrated excellent photocatalytic performance for the degradation of MB under both UV and sunlight irradiation with degradation rates of 0.04 and 0.03 min −1 , respectively and swiftly degraded the MB within 90 min. On the other hand, ZSAg degraded the MB dye faster with a rate of 4.5 × 10 −3 under sunlight as compared to UV light with a rate of 3.5 × 10 −3 . In addition, ZSAg with NaBH 4 exhibited superior catalytic activity for the reduction of Rhodamine B and 2-nitrophenol. These research findings highlight that the ZSAg composite is a promising potential catalyst, providing stability, reduction capability and utilising sunlight for the catalysis process.

Abstract Lightweight mechanical metastructures are widely used in the automotive industry and related transportation equipment due to their high specific strength, high specific stiffness, and designability. This study presents an auxetic cylindrical metastructure designed as a lightweight mechanical system with tunable stiffness and strength, offering promising applications in the automotive industry for energy absorption and structural components. The structure employs polylactic acid as the matrix material owing to its favorable printability and mechanical properties. Multiple samples with varying geometric parameters are fabricated via fused deposition modeling to validate the corresponding finite element models. Axial and lateral compression tests reveal distinct deformation mechanisms. Under axial loading, the metastructure exhibits significant necking behavior accompanied by auxetic expansion, with parameter T 3 critically influencing axial stiffness and strength through control of local buckling patterns. During lateral compression, pronounced bending deformation emerges, forming high elastic strain regions near connecting nodes and enabling adjustable lateral deformation. Parameters T 2 and T 3 primarily govern lateral nominal stiffness and strength by affecting deformation mode transitions. Multi-objective optimization using NSGA-II demonstrates a trade-off between the volume fraction and mechanical performance. The optimized design achieves significant mechanical property improvement, as numerically confirmed. This auxetic metastructure provides a novel approach for programmable lightweight system design, with potential applications spanning automotive industry, aerospace, biomedical, and impact-absorption engineering fields.

Abstract This review provides analysis of polymer composite scintillators, examining their fabrication techniques, optical and scintillation properties. Polymer composite scintillators represent an important class of radiation detection materials that combine the mechanical flexibility and processability of polymers with the high stopping power and scintillation efficiency of inorganic materials. Recent advances in nanomaterial synthesis, interface engineering, and manufacturing technologies have significantly expanded the performance envelope. This review systematically examines solution processing, melt processing, electrospinning, and additive manufacturing approaches for fabrication; light yield, energy resolution, and radiation hardness as critical performance metrics. Future research directions involving novel materials, advanced manufacturing techniques, and artificial intelligence-driven optimization are explored.