Core-shell Structure Research Articles

Heat transfer in a non-uniformly heated enclosure filled by NEPCM water nanofluid

Purpose This paper aims to focuses on by investigate the heat transmission and free convective flow of a suspension of nano encapsulated phase change materials (NEPCMs) within an enclosure. Particles of NEPCM have a core-shell structure, with phase change material (PCM) serving as the core. Design/methodology/approach The enclosure consists of a square chamber with an insulated wall on top and bottom and vertical walls that are differently heated. The governing equations are investigated using the finite element technique. A grid inspection and validation test are done to confirm the precision of the results. Findings The effects of fusion temperature (varying from 0.1 to 0.9), Stefan number (changing from 0.2 to 0.7), Rayleigh number (varying from 103 to 106) and volume fraction of NEPCM nanoparticles (changing from 0 to 0.05) on the streamlines, isotherms, heat capacity ratio and average Nusselt number are investigated using graphs and tables. From this investigation, it is found that using a NEPCM nano suspension results in a significant enhancement in heat transfer compared to pure fluid. This augmentation becomes more important for the low Stefan number, which is around 16.57% approximately at 0.2. Secondary recirculation is formed near the upper left corner as a result of non-uniform heating of the left vertical border. This eddy expands notably as the Rayleigh number rises. The study findings indicate that the NEPCM nanosuspension has the potential to act as a smart working fluid, significantly enhancing average Nusselt numbers in enclosed chambers. Research limitations/implications The NEPCM particle consists of a core (n-octadecane, a phase-change material) and a shell (PMMA, an encapsulation material). The host fluid water and the NEPCM particles are considered to form a dilute suspension. Practical implications Using NEPCMs in energy storage thermal systems show potential for improving heat transfer efficiency in several engineering applications. NEPCMs merge the beneficial characteristics of PCMs with the enhanced thermal conductivity of nanoparticles, providing a flexible alternative for effective thermal energy storage and control. Originality/value This paper aims to explore the free convective flow and heat transmission of NEPCM water-type nanofluid in a square chamber with an insulated top boundary, a uniformly heated bottom boundary, a cooled right boundary and a non-uniformly heated left boundary.

Innovative Core–Shell Tubular Structure in Polymer/Manganese–Nickel Oxide/Carbon Nanotube Blends for Electrochemical Components

ABSTRACTTo address the issue of electrochemical performance degradation resulting from redox reactions during the charging and discharging of supercapacitors, we introduced a novel electrode material featuring a core–shell attachment structure (PANI@(MnO2 + NiO)) with the incorporation of carbon nanotubes (CNTs). The introduction of CNT on top of the core–shell structure by a simple chemical synthesis method helps to improve the double‐layer capacitance and Faraday capacitance of the composite. Thus, multiple synergistic effects can be produced to improve charge storage capacity. The morphology structure and electrochemical properties of PANI@(MnO2 + NiO)@CNT were analyzed. In a three‐electrode configuration, the specific capacitance of the composite is 327 F g−1 at a current density of 0.5 A g−1. Remarkably, the capacitance retention rate exceeded 75% after 5000 charge–discharge cycles. Calculations indicate that in a supercapacitor employing a 1 M Na2SO4 electrolyte, the composite demonstrated energy and power densities of 48.1 W h kg−1 and 999.9 W kg−1, respectively. This kind of core–shell structural composites achieved electrochemical properties in line with expectations through a simple chemical synthesis method. As a practical application of supercapacitor electrode materials, PANI@(MnO2 + NiO)@CNT have better electrical properties than similar materials and have broad application prospects in industrial production.

Synthesis of silica-coated polygonal Fe3O4 nanoparticles

The small size, surface effect, and tunneling effect of nanomaterials enable their applications in various fields, including catalysis, sensing. Fe3O4 has been widely used in nanotechnology owing to its excellent photoelectromagnetic properties. In this study, polygonal Fe3O4 nanoparticles were prepared through a high-temperature synthesis method. Subsequently, silica coating was applied via the Stöber method to obtain a nanomaterial with uniform particles. The prepared Fe3O4 exhibited a distinct crystal structure and an ultra-high saturation magnetization, reaching up to 134.2 emu/g. Moreover, the dodecyl trimethyl ammonium bromide (DTAB) templating agent facilitated the coating of Fe3O4 with silica. The coated Fe3O4@SiO2 particles featured a well-defined core–shell structure and corrosion resistance, making them highly promising candidates for magnetic targeting medical tools, magnetic resonance imaging agents and other biological applications.

High order Fano resonance in the time domain for a freezing water microdroplet

Fog is a collection of micro drops of water suspended in the air, formed as a result of cooling of moist air. In supercooled air, water droplets freeze, forming ice fog at air temperatures below − 10–15° C. As the ice drop freezes, it forms a core-shell structure. In such a particle, a high-Q Fano resonance is possible, which entails the formation of a magnetic pulse. Our theoretical calculations have predicted the time-dependent formation of Fano resonances in a freezing the outside in water droplet. Time-varying unconventional Fano resonance with magnetic field enhancement yield new method to manipulate light–matter interactions in a freezing water droplet. To the best of our knowledge this mechanism was not discussed previously.

Co Hybrids modified piperazine pyrophosphate towards efficient flame retardancy, smoke suppression, and high mechanical properties of styrenic thermoplastic elastomer

The highly flammable nature of thermoplastic elastomers (TPE) results in poor fire safety performance. The large addition of flame retardants leads to a significant decrease in mechanical properties. To solve above challenges, we design a multilayer core-shell flame retardant, piperazine pyrophosphate@ tannic acid@ Co amorphous hybrids (PAPP@TA@Co-2-MIM) and add it to TPE to enhance the fire safety and mechanical performance simultaneously. It was found that the addition of 32 wt% PAPP@TA@Co-2-MIM achieved a UL-94 V-0 rating of TPE composites, with a limiting oxygen index of 27 %. Compared to pure TPE, the peak heat release rate, total heat release, total smoke production, and peak CO release rate of TPE/PAPP@TA@Co-2-MIM were reduced by 79.8 %, 37.1 %, 42.9 %, and 82.5 %, respectively, effectively suppressing the release of heat, smoke, and toxic gases. Besides, the flame-retardant mechanism was also explained. In terms of mechanical performance, benefiting by the bridging effect of the core-shell structure, the tensile strength of TPE/PAPP@TA@Co-2-MIM increased by 52.7 %, compared to TPE/PAPP. This study designed a TPE composite material that showed good thermal stability, high fire safety performance and enhanced mechanical properties.

Multi-Wavelength Excitable Multicolor Upconversion and Ratiometric Luminescence Thermometry of Yb3+/Er3+ Co-Doped NaYGeO4 Microcrystals.

Excitation wavelength controllable lanthanide upconversion allows for real-time manipulation of luminescent color in a composition-fixed material, which has been proven to be conducive to a variety of applications, such as optical anti-counterfeiting and information security. However, current available materials highly rely on the elaborate core-shell structure in order to ensure efficient excitation-dependent energy transfer routes. Herein, multicolor upconversion luminescence in response to both near-infrared I and near-infrared II (NIR-I and NIR-II) excitations is realized in a novel but simple NaYGeO4:Yb3+/Er3+ phosphor. The remarkably enhanced red emission ratio under 1532 nm excitation, compared with that under 980 nm excitation, could be attributed to the Yb3+-mediated cross-relaxation energy transfers. Moreover, multi-wavelength excitable temperature-dependent (295-823 K) upconversion luminescence realizes a ratiometric thermometry relying on the thermally coupled levels (TCLs) of Er3+. Detailed investigations demonstrate that changing excitation wavelength makes little difference for the performances of TCL-based ratiometric thermometry of NaYGeO4:Yb3+/Er3+. These findings gain more insights to manipulate cross-relaxations for excitation controllable upconversion in single activator doped materials and benefit the cognition of the effect of excitation wavelength on ratiometric luminescence thermometry.

Robust and Sustained STING Pathway Activation via Hydrogel-Based In Situ Vaccination for Cancer Immunotherapy.

The stimulator of interferon genes (STING) pathway is crucial for tumor immunity, leading to the exploration of STING agonists as potential immunotherapy adjuvants. However, their clinical application faces obstacles including poor pharmacokinetics, transient activation, and an immunosuppressive tumor microenvironment (TME). Addressing these limitations, our study aims to develop an injectable silk fibroin hydrogel-based in situ vaccine. It incorporates a nanoscale STING agonist, an immunogenic cell death (ICD) inducer, and an immunomodulator to ensure their controlled and sustained release. cGAMP nanoparticles (cGAMPnps) with a core-shell structure ensure optimal delivery of cGAMP to dendritic cells (DCs), thereby activating the STING pathway and fostering DC maturation. ICD-associated damage-associated molecular patterns amplify and prolong STING activation via enhanced type I IFN and other inflammatory pathways, along with delayed degradation of cGAMP and STING. Furthermore, the STING-driven vascular normalization by cGAMPnps and ICD, in conjunction with immunomodulators like antiprogrammed cell death protein 1 antibody (anti-PD-1 Ab) or OX40 ligand (OX40L), effectively remodels the immunosuppressive TME. This in situ gel vaccine, when used independently or with surgery as neoadjuvant/adjuvant immunotherapy, enhances DC and CD8+ T-cell activation, suppressing tumor progression and recurrence across various immunologically cold tumor models. It revolutionizes the application of STING agonists in cancer immunotherapy, offering substantial promise for improving outcomes across a broad spectrum of malignancies.

Bio-Templated Aerogel Fibers: Heterogeneous Spinodal Architecting and In Situ Fibrillation of Thermoplastic Polyurethane-Silica on Nanostructured Cellulose Nanofiber Scaffold for Enhanced Thermomechanical Performance.

This study addresses the inherent fragility and fractal limitations of traditional silica aerogels by developing a bio-templated aerogel fiber. Integrating cellulose nanofibers (CNFs), thermoplastic polyurethane (TPU), and silica aerogel (SA) in a dimethyl sulfoxide (DMSO) dispersion, a gel-spinning technique was employed to create aerogel fibers with superior thermomechanical performance. CNF also provided excellent rheological modification for successful spinnability, fast gelation, and fiber formation. The unique hierarchical structure of these fibers, formed through hot-stretching and surface modification, combined the superior mechanical strength and flexibility of TPU with the exceptional insulation properties of CNF and SA. The CNF network, encapsulated within the SA particles, formed a core-shell structure, axially aligned, that significantly enhances the thermal stability and mechanical performance of the fibers while maintaining a lightweight and porous architecture. Comprehensive morphological, thermal, and mechanical analyses were conducted to evaluate the properties of the developed aerogel fibers. Fourier transform infrared (FTIR) spectroscopy and nuclear magnetic resonance (NMR) spectroscopy verified the successful surface modification and grafting reactions on CNF, contributing to improved hydrophobicity and thermal insulation. Adjusting the CNF content allowed for tailoring of the thermomechanical characteristics, with a notable 294% increase in tensile strength from 5.3 to 15.6 MPa and an enhanced crystallization temperature from 106 to 119.97 °C. Furthermore, cyclic tensile and compression tests validated the durability and shape recovery capabilities of the aerogel fibers, making them promising candidates for high-performance applications in extreme environments. The thermal conductivity validated by experimental data further highlights the potential of CNF-based aerogel fibers as sustainable and multifunctional materials for advanced thermal insulation, mechanical reinforcement, and flexible structural applications.

Dressing AgNWs with MXenes Nanosheets: Transparent Printed Electrodes Combining High-Conductivity and Tunable Work Function for High-Performance Opto-Electronics.

High-work function transparent electrodes (HWFTEs) are key for establishing Schottky and Ohmic contacts with n-type and p-type semiconductors, respectively. However, the development of printable materials that combine high transmittance, low sheet resistance, and tunable work function remains an outstanding challenge. This work reports a high-performance HWFTE composed of Ag nanowires enveloped conformally by Ti3C2Tx nanosheets (TA), forming a shell-core network structure. The printed TA HWFTEs display an ultrahigh transmittance (>94%) from the deep-ultraviolet (DUV) to the entire visible spectral region, a low sheet resistance (<15 Ωsq-1), and a tunable work function ranging from 4.7 to 6.0eV. The introduction of additional oxygen terminations on the Ti3C2Tx surface generates positive dipoles, which not only increases the work function of the TA HWFTEs but also elevates the TA/Ga2O3 Schottky barrier, resulting in a high self-powered responsivity of 18mAW-1 in Ga2O3 diode DUV photodetectors, as demonstrated via experimental characterizations and theoretical calculations. Furthermore, the TA HWFTEs-based organic light-emitting transistors exhibit exceptional emission brightness of 5020cd m-2, being four-fold greater than that in Au electrodes-based devices. The innovative nano-structure design, work function tuning, and the revealed mechanisms of electrode-semiconductor contact physics constitute a substantial advancement in high-performance optoelectronic technology.

Analysis of mechanical properties and stress distribution in self-healing microcapsules using micro-compressive test, nanoindentation test, and finite element analysis

Abstract This study analyzed self-healing microcapsules composed of melamine, urea, and formaldehyde (MUF). The thin shell’s mechanical properties were predicted using various techniques to gain a comprehensive understanding of their behavior. The compressive behavior of the microcapsules was assessed through micro-compression testing. The elastic modulus of the thin shell was precisely determined using nanoindentation, a method known for its accuracy in measuring material properties. Finite element analysis (FEA) was then applied, modeling the microcapsule between two plates and treating the core, which contains the healing agent, as an incompressible liquid. The mechanical properties of the thin shell, based on the elastic modulus derived from the nanoindentation test, were incorporated into the FEA, and the results were compared with those from the micro-compression test. Additionally, we analyzed the von Mises stress distribution to evaluate stress concentration within the spherical core–shell structure, ensuring the reliability of our conclusions. The test methods and analysis techniques presented in this study provide guidelines for improving the stiffness of MUF microcapsules. They can be further applied to predict the properties of materials with a spherical core–shell structure.

Formation of core–shell structures and viscous fingering in cellulose beads regenerated from [DBNH][OAc]/DMSO

AbstractSuperbase Ionic Liquids (SBILs) are efficient direct-dissolution solvents for cellulose and have found applications such as manufacturing of man-made textile fibers. In this study cellulose beads were prepared from microcrystalline cellulose dissolved in a mixture of SBIL 1,5-diazabicyclo[4.3.0]non-5-enium acetate with dimethyl sulfoxide, [DBNH][OAc]/DMSO, by drop-wise regeneration using water as an antisolvent. This resulted in cellulose regeneration by spinodal decomposition phase separation. The cross-sections of freeze-dried beads were thoroughly investigated using SEM, revealing a complex internal bead structure. Special attention was paid to structures resulting from the inwards moving regeneration front, where the solvent and antisolvent interdiffuse in opposite directions. The phase boundary at the regeneration front showed evidence of Saffman–Taylor instability, i.e., viscous fingering. Altering the diffusion environment surrounding the bead during regeneration resulted in nested layers of cores and shells. The number and placement of the core–shell separations was regulated by the number of transfers between two antisolvent baths and the duration of alternating periods of fast and slow interdiffusion of water and [DBNH][OAc]/DMSO through the bead perimeter. Graphical abstract

LnIII/CuI Bimetallic Nanoclusters with Enhanced NIR-II Luminescence.

Coinage-metal clusters with excellent luminescence properties have attracted considerable interest due to their intriguing structures and potential applications. However, achieving strong near-infrared (NIR) luminescence in these clusters is highly challenging. Here, we have successfully synthesized the first LnIII/CuI bimetallic clusters, formulated as [LnCu54O6Cl3(2-MeO-PhC≡C)36] (ClO4)6 (Ln = Yb for YbCu54, Er for ErCu54, and Gd for GdCu54). Single crystal X-ray diffraction showed that the LnCu54 clusters have a three-layered core-shell structure, consisting of (LnO6)@Cu18Cl3@Cu36 units protected by 36 2-MeO-PhC≡C- ligands. Notably, the YbCu54 cluster exhibits significant NIR-II luminescence at 986 nm with the solid quantum efficiency of 33.3%, the highest among Cu clusters with NIR-II emission. This work not only reports the first category of LnIII/CuI clusters but also presents a method to enhance NIR luminescence in coinage-metal clusters through the incorporation of LnIII ions.

High Coverage Sub-Nano Iridium Cluster on Core-Shell Cobalt-Cerium Bimetallic Oxide for Highly Efficient Full-pH Water Splitting.

The construction of sub-nanometer cluster catalysts (<1nm) with almost complete exposure of active atoms serves as a promising avenue for the simultaneous enhancement of atom utilization efficiency and specific activity. Herein, a core-shell cobalt-cerium bimetallic oxide protected by high coverage sub-nanometer Ir clusters (denoted as Ir cluster@CoO/CeO2) is constructed by a confined in situ exsolution strategy. The distinctive core-shell structure endows Ir cluster@CoO/CeO2 with enhanced intrinsic activity and high conductivity, facilitating efficient charge transfer and full-pH water splitting. The Ir cluster@CoO/CeO2 achieves low overpotentials of 49/215, 52/390, and 54/243mV at 10mAcm-2 for hydrogen evolution reaction/oxygen evolution reaction (HER/OER) in 0.5m H2SO4, 1.0m PBS, and 1.0m KOH, respectively. The small decline in performance after 300h of operation renders it one of the most effective catalysts for full-pH water splitting. DFT calculations indicate that oriented electron transfer (along the path from Ce to Co and then to Ir) creates an electron-rich environment for surface Ir clusters. The reconstructed interface electronic environment provides optimized intermediates adsorption/desorption energy at the Ir site (for HER) and at the Ir-Co site (for OER), thus simultaneously speeding up the HER/OER kinetics.

Sub-10 nm PdNi@PtNi Core–Shell Nanoalloys for Efficient Ethanol Electro-Oxidation

By controlling the structure and composition of Pt-based nanoalloys, the ethanol oxidation reaction (EOR) performances of Pt alloy catalysts can be effectively improved. Herein, we successfully synthesis sub-10 nm PdNi@PtNi nanoparticles (PdNi@PtNi NPs) with a core–shell structure by a one-pot method. The sub 10 nm core–shell nanoparticles possess more effective atoms and exhibit a synergistic effect which can lead to a shift in the d-band center and alter binding energies toward adsorbates. Due to the synergistic effect and unique core–shell structure, the PdNi@PtNi NP catalysts exhibit excellent electrocatalytic performance for ethanol oxidation reactions in alkaline, achieving 9.30 times more mass activity and 7.05 times more specific activity that of the state-of-the-art Pt/C catalysts. Moreover, the stability of PdNi@PtNi NPs was also greatly improved over PtNi nanoparticles, PtPd nanoparticles, and commercial Pt/C. This strategy provides a new idea for improving the electrocatalytic performance of Pt-based catalysts for EORs.

Fast and on-site detection of fenthion in rice using core-shell Au@Ag nanoparticles and a portable Raman spectrometer

The residue of pesticide fenthion is a common issue in food safety, and how to conveniently detect it is a challenge in the food industry. Therefore, combined with a portable Raman spectrometer, a surface enhanced Raman spectroscopy (SERS) method based on a high-performance substrate Au@AgNPs had been designed for the rapid and sensitive detection of fenthion. Au@AgNPs can be induced to generate more hot spots to improve SERS signals because of their core-shell structure. The quantitative detection of fenthion was achieved under the optimal conditions: pH 7.0, 10−3 M CaCl2, 70 % Au@AgNPs concentration, and 4 min of incubation time. The results showed that the method had a wider detection range of 0.1–100 mg/L, a low detection limit (LOD) of 0.036 mg/L, excellent anti-interference ability, and reproducibility. In addition, the method was successfully validated with the actual sample rice. Therefore, the method had the advantages of being fast, on-site, and easy to use, which is useful for promoting its application.

Cascade enzyme-mimicking with spatially separated gold-ceria for dual-mode detection of superoxide anions

Metal-semiconductor nanozyme of dumbbell Au-CeO2 with spatially separated heterostructure has cascade superoxide dismutase (SOD)-like and peroxidase (POD)-like activities for superoxide anions detection. It was synthesized by selective growth of CeO2 at the ends of Au nanorod (Au NR). Taking advantage of the excellent local surface plasmon resonance (LSPR) effect of Au NR, the spatially separated Au-CeO2 has a higher photothermal effect than the continuously growing core-shell structure of Au@CeO2. Meanwhile, the hot electrons of Au NR could transfer to CeO2 under 808 nm laser irradiation, changing the ratio of Ce3+/Ce4+ redox couples over CeO2 and facilitating H2O2 decomposition thus enhancing POD-like activity. Based on the SOD-like activity of Au-CeO2, superoxide anion (O2·−) can be transformed into hydrogen peroxide (H2O2). Dual-mode including absorbance and temperature sensing detection of O2·−, with the detection range from nM to μM i.e., 0.1–150 μM and LOD of 0.033 μM (S/N = 3) was achieved through the cascade catalysis and photothermal effect. The as-proposed method was applicable to both cancer and normal cell samples with satisfactory accuracy and recovery.

A multifunctional platform based on ZIF-67 templated NiCo-LDH and Fe3O4 hollow spheres for photocatalytic CO2 conversion and supercapacitors

This work presented a series of hybrid materials F@P-LDHs exhibiting the core-shell structure with PPy as the interface modifier, explored as dual-functional materials for studying photocatalytic reduction of CO2 and electrochemical behaviors. F@P-LDHs served as photocatalysts, effectively convert CO2 into CO without using any sacrificial agents and photosensitizers via the gas-solid mode under the visible light irradiation. The generation rate of CO was as high as 10.32 μmol g−1h−1, which was 5.4 and 6.4 times higher than the original Fe3O4@PPy and NiCo-LDH. The well performance might be ascribed to the generation of type Z heterojunction with the interface modifier PPy, jointly accelerating the separation and migration of photo-generated charge carriers between Fe3O4@PPy and NiCo-LDH. Besides, F@P-LDHs were also developed as supercapacitors, and their electrochemical behaviors were investigated. Their good electrochemical performances were attributed to the synergistic effect among hollow Fe3O4 microspheres, polypyrrole and NiCo-LDH. Therefore, as dual-functional materials, the hybrid materials have great potential in the field of CO2 conversion and supercapacitors.

Effect of T’-YSZ@Al2O3 core-shell structure on fracture toughness of YSH24 ceramics

To meet the demands of higher operating temperatures in aero-engines, yttrium oxide fully stabilized cubic (C) phase hafnium oxide (YFSH) has emerged as a promising candidate for thermal barrier coatings due to its ultra-high melting and phase transition temperatures. However, its application is constrained by its inherently low fracture toughness. To enhance the fracture toughness of C-HfO2 phase ceramic, the metastable non-equilibrium tetragonal (T’) phase of Y0.08Zr0.92O1.96 (YSZ8) was synthesized using the sol-gel method. An Al2O3 layer was then coated on YSZ, forming a T’-YSZ@Al2O3 core-shell structure (with Al2O3 comprising 20 % of the YSZ volume). The phase organization stability and diffusion resistance of this T’-YSZ@Al2O3 core-shell structure were investigated. Composite ceramic bulks, with compositions x T’-YSZ@Al2O3/(1-x) YSH24 (where x is the volume fraction, x = 0, 0.1, 0.2, 0.3, 0.4), were prepared using spark plasma sintering (SPS). The impact of the T’-YSZ@Al2O3 addition on the fracture toughness of the YSH24 matrix and the toughening mechanisms were analyzed. The results indicate that the introduction of the T’-YSZ@Al2O3 core-shell structure with good structural integrity into YSH24 ceramics prevents phase transitions. As the volume fraction of the core-shell structure increases from x = 0–0.4, the fracture toughness initially rises and then decreases, reaching a maximum of 2.36 MPa·m1/2 at x = 0.3. This value represents a 38.8 % improvement compared to that of the single C-HfO2 phase YSH24 bulks. The primary toughening mechanism is attributed to the ferroelastic domain switching of T’-YSZ within the T’-YSZ@Al2O3 core-shell structure.

Core-shell MIL-53(Al)–NH2@UiO-66 coated solid-phase microextraction Arrow for the selective enrichment of nine alkylphenols in milk

Metal-organic frameworks (MOFs) hold significant potential for sample preparation, but single-MOF materials often face limitations in selectivity and extraction efficiency. To overcome these, a mesoporous MIL-53(Al)–NH2@UiO-66 composites with a core–shell structure was synthesized using an epitaxial growth strategy. This composite leverages the complementary properties of both MOFs, offering enhanced active sites and interaction forces for analytes. The structure and integration of the composite were characterized using Fourier-transform infrared spectroscopy, scanning electron microscopy, and X-ray diffraction, confirming their successful integration. To address the challenge of detecting alkylphenols (APs) in food matrices, known for their endocrine-disrupting properties and low concentrations, a new solid-phase microextraction (SPME) Arrow was fabricated using the MIL-53(Al)–NH2@UiO-66 composite combined with polyacrylonitrile as a binder. APs were detected using ultra-performance liquid chromatography and quadrupole time-of-flight tandem mass spectrometry (UPLC-ESI-Q-ToF/MS). The developed SPME Arrow-UPLC-ESI-Q-ToF/MS method exhibits good linearity (R2 ≥ 0.9958), wide linear range (0.01–1000 μg L–1), and high sensitivity (limits of detection ranging from 0.005 to 0.01 μg L–1) for APs determination. This method was validated for determining nine APs in milk samples from various packing materials, with spiked recoveries ranging from 85.2 % to 115 % and relative standard deviations from 3.4 % to 13.6 %. This study demonstrates the potential of MOF-on-MOF composites in enhancing the performance of adsorbents for SPME pretreatment, offering a promising approach for improving analytical methodologies in food safety.

Preparation of core-shell Si/C/graphene composite for high-performance lithium-ion battery anodes

One of the important objectives for the development of enhanced lithium-ion batteries is developing high-performance silicon-based anodes with durable operational capability. Herein, a three-dimensional graphene-decorated core-shell Si/C composite is fabricated by the in-situ polymerization of organic pyrrole molecule and pyrolysis process, in which the melamine formaldehyde resin is subtly used as three-dimensional porous framework to offer abundant loading area for the uniform dispersion of active silicon nanoparticles. Meanwhile, the core-shell structure deriving from polypyrrole in the composite can effectively buffer the volume change of silicon ingredient and avoid the direct contact with the electrolyte during the cycling process, leading to the improved structural stability and electrochemical performance. The outermost layer of graphene nanosheets is designed to enhance the electrical conductivity of the electrode. As a result, the synthesized Si/C/graphene composite exhibits a high capacity and excellent cycling performance. This work reveals that combining a three-dimensional carbon substrate with a core-shell structure might be a promising solution for anode materials with obvious volume transformation.