Electrostatic Method Research Articles

Self-Assembled Serpentine Ni3Si2O5(OH)4 Hybrid Sheets with Ammonium Polyphosphate for Fire Safety Enhancement of Polylactide Composites.

Biodegradable polylactide (PLA) has been widely utilized in people's daily lives. In order to improve the fire safety of PLA, ammonium polyphosphate (APP) was self-assembled onto the surface of serpentine Ni3Si2O5(OH)4 through the electrostatic method, followed by mixing with PLA by melt compounding. The APP-modified serpentine (serpentine@APP) dispersed uniformly in the PLA matrix. Compared with pure PLA, the PLA composite with 2 wt% serpentine@APP reduced the peak heat release rate (pHRR) and total heat release (THR) by 43.9% and 16.3%, respectively. The combination of APP and serpentine exhibited suitable synergistic flame-retardant effects on the fire safety enhancement of PLA. In addition, the dynamical rheological tests revealed that the presence of APP and serpentine could reduce the viscosity of PLA composites. The plasticizing effects of APP and serpentine benefited the processing of PLA. The mechanical properties of PLA/serpentine@APP maintained suitable performance as pure PLA. This study provided a feasible way to enhance the fire safety of PLA without sacrificing its mechanical properties.

Microplastics in soil: Current status and evaluation of the greenness of various analytical methods of identification

• Terrestrial environments can be considered as potential sinks of Microplastics (MPs). • Both primary and secondary sources of MPs contribute to a significant amount of MPs in soil. • The greenness of analytical methods can be evaluated using AGREE software. • The electrostatic separation method of MPs can be considered as green quantification method. Microplastics (MPs) have received increasing attention because of their ubiquitous and persisting nature and high degree of resistance to degradation, and bioaccumulation. There has been growing evidence of their direct and indirect impacts on the ecosystem's health. Although the extensive research has been carried out to assess the impact of MPs on aquatic environment, terrestrial environment is a significant research hotspot that needs to be focused more as it is highly polluted by anthropic plastic usage. The overarching aim of this study was to assess the current research trends on MPs analysis and the evaluation of the greenness of existing quantification methods, particularly in soil samples. In the last three years the trend in the quantification of MPs in soil media is found to be exponential and few studies have reported significant concentration of MPs of about 85,000 particles per kg dry weight of soil samples, raising an alarm to the policy makers to implement stringent policies. It has been observed that the existing quantification methodologies are not following the sustainable principles of green analytical chemistry due to their low score obtained from AGREE method. In this context, the electrostatic method of separation of MPs can be considered green, while the magnetic and Olive oil-based separation methods are classified as worse based on the greenness parameter. This paper attempts to provide some new information on the implementation of sustainable methods of MP quantification.

Structural, optical and electronic properties of copper doped TiO2: Combined experimental and DFT study

• Electronic properties of TiO 2 with the low doping concentration of Cu has been calculated. • The microstructures of the Cu-TiO 2 nanoparticles deposited on film. In this paper, we demonstrate that the low Cu doping concentration modifies electronic properties of TiO 2 through experimental and computational studies (Density Functional theory-DFT). Cu-to-TiO 2 thin films with different Cu wt% were prepared by electrostatic spray pyrolysis method. The effect of Cu doping on TiO 2 were analyzed using various characterizations such as X-ray diffraction (XRD), ultraviolet-visible (UV-Vis) spectroscopy, Raman spectroscopy, and scanning electron microscopy. The XRD reveals that the Cu-doped TiO 2 crystallizes in a tetragonal structure with an anatase phase. Raman spectroscopy confirmed the presence of strong chemical bonds and functional groups at the TiO 2 interface. UV-Vis spectroscopy was used to record the optical characteristics of doped and undoped samples. Uv-Vis spectroscopy revealed a reduction in band gap after doping. Surface morphology of the Cu-doped TiO 2 thin films were analysis using SEM. SEM images revealed no significant changes in particle size or microstructures of the synthesized materials. Additionally, DFT modelling was carried out to confirm the effects of dopants on electronic properties of the thin film. The results were analyzed, and the experimental results were corroborated, by the analysis.

Silica decorated with Ti3C2Tx nanosheets for reinforcing epoxy resin dielectric properties and energy density

Advances in electronic technology and power devices have placed increased demands on the performance of polymer dielectrics. The preparation of dielectric polymer composites with high dielectric constant and breakdown strength remains a critical challenge. Herein, SiO 2 @Ti 3 C 2 T x hybrids were prepared by decorating few-layer Ti 3 C 2 T x nanosheets on the surface of modified silica nanospheres by electrostatic self-assembly method. A series of EP/SiO 2 @Ti 3 C 2 T x composites were prepared by using the heterohybrids as fillers, and the composites demonstrated the enhanced dielectric constant and breakdown strength. After filling with 7 wt% of SiO 2 @Ti 3 C 2 T x , the dielectric constant of the composite was 4.25. At this point, the breakdown strength of the composite is 41.6 kV/mm, and the dielectric loss at 1 kHz is 0.005. The improved performance of epoxy resin-based composites can be attributed to the fact that Ti 3 C 2 T x nanosheets contain surface hydroxyl groups capable of improving the dispersion of fillers in epoxy resin, while the addition of Ti 3 C 2 T x nanosheets improves the interfacial polarization behavior. The reasonably designed nano-hybrid filler has broadened the application of polymer dielectric in energy storage, power equipment and other engineering fields. • Hybrid with core-shell structure was synthesized by electrostatic assembly strategy. • The effect of dielectric parameter control on the energy storage property is exposed. • The relationship between filler content and resin intrinsic properties is studied. • The maximum U dis of the composite is 6.45×10 -2 J/cm 3 when the filling is 7 wt%.

Rational designed microstructure pressure sensors with highly sensitive and wide detection range performance

• High sensitivity (26.55 kPa −1 ) and wide work range (0.9 Pa-140 kPa) pressure sensor was demonstrated. • Micro-nano hierarchical structure sponge surface with random uneven pattern. • PDMS sponge fabricated via mixed sacrifice template and electrostatic self-assembly methods. • The pressure sensor has great potential for healthcare and human-machine interfaces. Highly sensitive pressure sensors are often deployed in human-machine interaction area, touch screen and human motion detection. However, there are still great challenges to fabricating with high sensitivity pressure sensor with wide-range detection. Herein, we developed a new strategy to fabricate a highly sensitive pressure sensor using sandpaper and improve its detection range using a sacrificial template. It was the fthatirst time to combine microstructure processing with the sacrificial template method to fabricate pressure sensor. The microstructure of sandpaper endowed the sensor with high sensitivity, and the elastic substrate enhanced the sensor ability to resist high pressure without being damaged. The fabricated sensor device exhibits a superior sensitivity of 39.077 kPa −1 in the range from 50 kPa to 110 kPa with a broad linear response. Remarkably, high pressure ceiling (<160 kPa) ensures that the sponge could be applied in different practical conditions to monitor a range of subtle human motions including finger, wrist bending, and pulse. For applications, the sensor device can not only detect the foot stepping behavior (0.7 MPa) but also produce an obvious response to an extremely slight paper (9 mg, ∼0.9 Pa). The successful preparation of this micro-structured elastic sponge material provided new ideas for exploring its potential applications in pressure sensors and flexible wearable electronic devices.

Atomically dispersed Co/C3N4 for boosting aerobic cyclohexane oxidation

The atomically-dispersed and high-loading Co on graphitic carbon nitrogen (Co/C3N4-w, w representing the molar ratio of Co to melamine in the synthesis recipe) was synthesized by coupling the one-pot strategy with the electrostatic adsorption method and used for the solvent-free aerobic oxidation of cyclohexane. The characterization results of Co/C3N4-w revealed that the single-atom Co with the positive charge existed in the sixfold cavities of C3N4 and was stabilized by the CoN interaction along with the electron transfer from Co atoms to C3N4. The catalytic activity of Co/C3N4-w presented the positive correlation with the loading of the single-atom Co, and the superior catalytic performance with 21 % conversion and 95 % overall selectivity was obtained over Co/C3N4-0.02, which also exhibited the excellent universality to the aerobic oxidation of other cycloalkanes and alkyl aromatics. Experiments combined with density functional theory calculations demonstrated that the favored O2 dissociation and intermediate cyclohexylhydroperoxide decomposition on the low-coordinated single-atom Co, and the promoted adsorption of cyclohexane on the electron-rich C3N4 surface, synergically boosted the cyclohexane oxidation. Distinctively, the high stability of Co/C3N4-0.02 in the cyclohexane oxidation originated from the robust single-atom Co structures and hydrophobic C3N4 surface.

Bismuth-Based BiOBrxI1–x/Ti3C2 MXene Schottky Nanocomposites for Hg2+ Photoelectrochemical Sensors

BiOBrxI1–x/Ti3C2 Schottky heterojunction nanocomposites were prepared through a simple electrostatic adsorption and self-assembly method. The Schottky heterojunction was used as a sensitive material in the fabrication of a photoelectrochemical (PEC) sensor for mercury ion detection. Due to the large specific surface area, excellent electrical conductivity, and abundant surface chemical groups of the 2D nano Ti3C2 in the Schottky heterojunction, the in situ growth of solid solution BiOBrxI1–x on its surface enabled the nanocomposites to form a high Schottky barrier to improve the sensitivity of the PEC response. The addition of glutathione (GSH) caused it to adhere to the surface of the nanocomposites where it hindered the transfer of electrons and reducing the photocurrent by reacting with the bismuth ions on their surface through its carboxyl groups. During the Hg2+ assay, Hg2+ ions reacted to GSH on the surface of the heterojunction nanocomposites, and then captured more GSH in a solution to form a complex with 3D structure. This complex further hindered electron transfer and led to a sharp decrease in photocurrent. A trace amount of Hg2+ was detected based on the change of photocurrent, with a linear range of 1.0 × 10–10 mol/L to 1.0 × 10–6 mol/L and a detection limit of 4.21 × 10–11 mol/L. This method was one of the most sensitive methods reported for Hg2+ detection. The sensor had been applied to determine trace mercury in environmental water samples.

Quantifiable Effect of Interparticle Plasmonic Coupling on Sensitivity and Tuning Range for Wavelength-Mode LSPR Fiber Sensor Fabricated by Simple Immobilization Method

Herein a gold nanosphere (AuNS)-coated wavelength-mode localized surface plasmon resonance (LSPR) fiber sensor was fabricated by a simple and time-saving electrostatic self-assembly method using poly(allylamine hydrochloride). Based on the localized enhanced coupling effect between AuNSs, the LSPR spectrums of the AuNS monolayer with good dispersity and high density exhibited a favourable capability for refractive index (RI) measurement. Based on the results obtained from the optimization for AuNS distribution, sensing length, and RI range, the best RI sensitivity of the fiber modified by 100 nm AuNS reached up to about 2975 nm/RIU, with the surrounding RI range from 1.3322 to 1.3664. Using an 80 nm AuNS-modified fiber sensor, the RI sensitivity of 3953 nm/RIU was achieved, with the RI range increased from 1.3744 to 1.3911. The effect of sensing length to RI sensitivity was proven to be negligible. Furthermore, the linear relationship between the RI sensitivity and plasma resonance frequency of the bulk metal, which was dependent on the interparticle plasmon coupling effect, was quantified. Additionally, the resonance peak was tuned from 539.18 nm to 820.48 nm by different sizes of AuNSs-coated fiber sensors at a RI of 1.3322, which means the spectrum was extended from VIS to NIR. It has enormous potential in hypersensitive biochemistry detection at VIS and NIR ranges.

Preparation and properties of polylactic acid (PLA) antibacterial nanofiber membrane with Ag@TP composite antibacterial agent

This paper presented the composite antibacterial agent of nano-silver (Ag) and tea polyphenol (TP) by bioreduction method. Then polylactic acid (PLA) nanofiber membranes with different antibacterial content were prepared by electrostatic spinning method. The morphologies, structural characteristics and properties of electrostatic spun fiber membranes were investigated by scanning electron microscope (SEM), infrared spectroscopy (FTIR), electronic single fiber strength machine and flat colony counting method. The results showed that Ag@TP was loaded with silver nanoparticles with uniform particle size distribution. When the content of Ag@TP of electrospun fiber was less than 2.0%, the diameter of electrostatic spinning fiber was uniformly distributed and had smooth surface. It could be seen from the FTIR spectrum that Ag@TP and PLA were well compounded through valence bonds. As the content of antibacterial agent increased, the elongation at break of the fiber membrane first decreased and then increased. While the breaking strength was found to first decrease, then increase and decrease again. The water contact angle of the fiber membrane was gradually decreased with the increase of the antibacterial agent content. When the amount of Ag@TP was added 2.0%, the relative antibacterial rate of the electrospun fiber membrane to E.coli and S.aureus was as high as 95%, indicating an excellent antibacterial effect.

Spontaneous and Electrically Induced Anisotropy of Composite Agarose Gels.

Agarose gels containing and not bacteriorhodopsin purple membranes (incorporated before gelling) manifest spontaneous optical anisotropy. The dependencies of the anisotropy on the agarose concentration and time have been studied. The rise in the anisotropy is explained by the predominant orientation of the agarose fibers during the gelling and subsequent deformation of the gel net. In the electric field, additional optical anisotropy rises, which is caused by the orientation of the membranes. A procedure has been developed to separate electrically induced and spontaneous anisotropy in composite gels. The isoelectric points and surface electric potential of bacteriorhodopsin trimer and purple membranes are calculated by the method of protein electrostatics to explain their electric asymmetry, which leads to perpendicular orientation in the direct electric field and longitudinal in the kilohertz sinusoidal field. The results allow for an increase in the separation capability of composite gels of electrophoresis for macromolecules with different sizes by applying an appropriate electric field to modulate the effective pore size.

Constructing Z-scheme Fe3N/BiVO4 heterojunction via electrostatic self-assembly toward high visible-light photocatalytic hydrogen evolution

Fe3N/BiVO4 nanocomposites without noble metals were synthesized by a simple electrostatic self-assembly method. The morphology, crystal structure, composition and properties of the samples were studied by XRD, SEM, TEM, UV–vis and XPS. Under visible light irradiation, the average hydrogen production efficiency of 9 wt% Fe3N/BiVO4 nanocomposites reached 1420.7 μmol h−1 g−1, about 4 times than that of pure BiVO4. After four cycle experiments, the hydrogen production of 9 wt% Fe3N/BiVO4 is basically the same, indicating that the sample has good cycle stability. The enhancement of the activity and stability of the photocatalyst is mainly due to the fact that Fe3N is loaded on the surface of BiVO4, forming a Z-scheme heterojunction, which hinders the recombination of photogenerated electron hole pairs and greatly improves the separation efficiency of charge carriers.

Constructing a perfect, efficient heterojunction catalyst with HNO3 protonated C3N4 and GO-derived GOQDs via electrostatic self-assembly

To improve the photocatalytic performance, carbon nitride (C3N4) heterojunctions with carbon nanomaterials are being developed. Here, the electrostatic self-assembly method was used to create the GOQDs (graphene oxide quantum dots)/Hp-C3N4 (HNO3 protonated carbon nitride) heterojunctions. Poor dispersion and weak interface bonding were addressed by using GOQDs, a derivative of graphene oxide (GO). The specific surface area of the GOQDs/Hp-C3N4 heterojunction increased from 7.445 m2/g to 33.634 m2/g, and the valence band potential increased from 2.016 eV to 2.367 eV. The GOQDs/Hp-C3N4 could generate higher levels of •OH and superoxide radicals (•O2-). The degradation efficiency of the heterojunction for pollutants (MO) under visible light was increased by 343, 9, and 4 times in comparison to C3N4, Hp-C3N4, and GO/Hp- C3N4, respectively. Our results showed that GOQDs derived from GO with smaller sizes and higher abundances of oxygen-containing functional groups make better co-catalysts for constructing heterojunctions with C3N4 to boost photocatalytic performance.

Post treatment and properties of PVA/SS composite nanofibers

Using deionized water as a solvent, the polyvinyl alcohol/silk sericin (PVA/SS) mixed solution was prepared, and the PVA/SS composite nanofiber membrane was spun by the electrostatic spinning method. The characteristics and properties of the PVA/SS composite nanofiber membrane untreated and treated with methanol and ethanol steam were analyzed by scanning electron microscope, infrared spectrum and X-ray diffraction. The results showed that the morphology of the PVA/SS composite nanofibers was fine in this experiment. The average diameter and standard deviation of diameter first increased, then decreased and at last increased with the increase of the SS content. The average diameter of nanofibers treated with methanol and ethanol steam was smaller than that without treatment. The infrared spectrum showed that the peak value of SS in the PVA/SS composite nanofibers treated with methanol steam and ethanol steam for 3 d changed. X-ray diffraction showed that the crystallization of the PVA/SS composite nanofiber membrane after being treated with methanol and ethanol vapor was changed. The results provide theoretical support for biomedical materials and tissue engineering scaffolds.

Self-assembled double core-shell structured zeolitic imidazole framework-8 as an effective flame retardant and smoke suppression agent for thermoplastic polyurethane

The addition of traditional flame retardant additives can usually significantly reduce the flammability of thermoplastic polyurethane (TPU) but has a limited contribution to suppressing smoke release during combustion. To overcome this obstacle, a double core-shell structured zeolite imidazole framework-8 (ZIF-8) in combination with negatively charged phytic acid and positively charged hyperbranched polysiloxane (NH2-HBPSi) was layer-by-layer self-assembled through the electrostatic method. The decorated NH2-HBPSi layer effectively improved the interfacial compatibility between the fillers and the TPU matrix. The peak heat release rate (PHRR), total heat release (THR), total smoke production (TSP), and total CO production (TCOP) of the TPU composite containing 2.0 wt% ZIF-8@PA@NH2-HBPSi were reduced by 35.2%, 25.2%, 65.5%, and 52.8%, respectively, as compared to those of pure TPU. The distinguished fire resistance and smoke suppression were ascribed to the flame retardant effects of Zn, N, P, and Si elements in the ZIF-8@PA@NH2-HBPSi hybrid. In addition, the TPU/ZIF-8@PA@NH2-HBPSi composite maintained a high elongation at break of 2178.2% and tensile strength of 46.87 MPa due to the steric effect of NH2-HBPSi. This work presents a feasible strategy for the design and development of flame retardant fillers to improve fire resistance and inhibit smoke emission while maintaining the high ductility of TPU.

Sea-urchin-like NiCo2S4 modified MXene hybrids with enhanced microwave absorption performance

The development of electromagnetic wave absorbing materials with lightweight and high absorption capacity is an effective way to solve electromagnetic wave pollution. Although the two-dimensional MXene material has become one of the most attractive electromagnetic wave absorbing materials due to its unique structure, the poor impedance matching makes it difficult to obtain both lightweight and efficient absorption capacity. Herein, few-layer MXene sheets and sea-urchin-like NiCo2S4 (NCS) hybrids were successfully synthesized by a simple electrostatic self-assembly method. MXene/NCS hybrids achieve good absorption performances. The maximum absorption bandwidth is 5.6 GHz at a matching thickness of only 1.53 mm with a filling ratio of only 10 wt%. In addition, the excellent microwave absorption performance is attributed to the improved impedance matching of MXene and the synergistic effects of dielectric loss and interfacial polarization. This work provides new ideas for the design and synthesis of materials with lightweight and efficient electromagnetic wave absorption.

Near-infrared light-responsive MnOx/Ag3PO4 heterojunction for rapidly eradicating sternal fracture implant infection

Bacterial infection in open implant surgery usually causes surgery failure and afflicts patient. Herein, a near-infrared light-responsive MnOx/Ag3PO4 heterojunction is designed for rapidly eradicating sternal fracture implant infection. Specifically, MnOx and Ag3PO4 coatings on Ti substrate are prepared by one-step low-temperature hydrothermal method and ion exchange and electrostatic adsorption methods, respectively. Notably, the internal electric field in the MnOx/Ag3PO4 heterointerface facilitates the migration of photogenerated electrons. Correspondingly, this heterojunction can produce abundant reactive oxygen species and local heat (∼53 °C) against Staphylococcus aureus (antibacterial rate is 99.5%) and Escherichia coli (antibacterial rate is 98.8%) for 15 min 808 nm NIR light irradiation. The in vivo experiment also confirmed the hybrid coating on sternal fracture implant exhibits good biosafety and effectively eradicates bacterial infection. This strategy may provide new insight into light-responsive antibacterial implant in open surgery.

Hollow porous Co3O4/NC@rGO derived from reuleaux tetrahedral ZIF-67 as a promising anode material for Li-ion batteries

Constructing advanced nanostructures and combining various active materials are effective strategies to obtain high-performance anode materials for lithium-ion batteries (LIBs). Herein, we report a surface-coordinated polymerization method to synthesize ZIF-67 nanoparticles with a reuleaux tetrahedron morphology, and combine the electrostatic adsorption method and heat treatment, nitrogen-doped hollow porous Co3O4 (HP-Co3O4/NC) nanoparticles were anchored on reduced graphene oxide (rGO) to obtain HP-Co3O4/NC@rGO composites. This deliberate structural design can significantly improve the electrochemical performance of lithium (Li) storage. When applied as an anode material in LIBs, HP-Co3O4/NC@rGO nanocomposite renders a reversible capacity of 809 mAh g−1 after 200 charge/discharge cycles at a current density of 1000 mA g−1. The excellent electrochemical performance is mainly attributed to the synergistic effect of the hollow nanostructure and graphene network. A hollow nanostructure can provide abundant active sites and enhance structural stability. As a conductive network, graphene tightly wraps Co3O4, which can not only increase the electronic and ionic transport but also alleviates the volumetric changes of Co3O4 during the charge/discharge process, thereby improving the rate performance and cyclic stability.

절연유 내 이온 주입을 통한 미세입자 크기별 제거 특성

Since contamination of insulating oil causes partial discharge and mechanical malfunction, it is necessary to remove internal fine particles. Currently an electrostatic filter method is being actively studied to remove particles inside the non-conductive liquids, however this method has the drawback of being time-consuming. Recently an electrostatic filter with ion injection has been created to deal with the issue of taking a long time, however there hasn’t been enough research on removing particles of various sizes. This study used an electrostatic filter with an ion injection to remove particles of various sizes. Up to 72% of the 100 mesh-sized particles were removed after using a needle-plate electrode for 180 seconds after adding PE particles to the transformer oil. This result can be applied to studies on electrostatic force-based removal of fine dielectric particles from non-conductive liquids.

The turbulent-flow-assisted electrostatic collection and alignment of recycled short-chopped carbon fiber in gaseous phase

Short-chopped carbon fiber is a main recycled product of carbon fiber materials that shows great advantage of anisotropy on mechanical or functional properties; however, their considerable agglomeration leads to limitations of separating and controlling individual fiber’s placement and orientation to fine-tune properties of final composite materials. Here we report a turbulent-flow-assisted electrostatic collection and alignment method that results in exceptional disentanglement efficiency, good collection and launching efficiency with great orientation performance in the gaseous phase. The pneumatic dispersion shows a nearly complete disentanglement efficiency (97 %) at a pressure reduction of 0.5 MPa, which ensures full utilization of electrostatic property for each disentangled fiber. By energization of the dielectric layer at different voltage levels, re-entrainment of conductive carbon fiber was avoided, while the collection and launching efficiency could reach 62 % and 47 %, respectively. By fast-frame imaging, the disentanglement, migration, landing and launching process was studied. The electrostatic polarization for launching leads to free-angle flocking that over 97 % of short fibers were controlled to be aligned within azimuthal angle from 60° to 90° regardless of launching angle. The combined disentanglement and alignment offer an attractive material system for recycling short-chopped carbon fibers and fabricating reinforced or functionalized composite materials.

Carbon Nanocoils and Polyvinyl Alcohol Composite Films for Fiber-Optic Fabry–Perot Acoustic Sensors

Carbon nanocoils (CNCs) are widely used in functional devices due to their helical morphology, which can be utilized in the fabrication of functional materials with unique properties. In this study, CNCs/polyvinyl alcohol (PVA) composite films were prepared using an electrostatic spinning method and used to form a diaphragm for Fabry–Perot acoustic sensors. With the addition of CNCs, the fabricated composite film showed enhanced mechanical performance responding to acoustic wave pressure. Considering the optical and mechanical response, the content of CNCs was set as 0.14 wt.%; the highest acoustic wave pressure response of the sensor was 1.89 V/Pa at 16.2 kHz, which was relatively higher than that of devices with pure polymer films. Additionally, the sensor had a broadband frequency response from 2 to 10 kHz. The results indicate that the proposed composite film acoustic sensor is suitable for low-frequency acoustic sensing, which lays the foundation for the extended application of functional sensors based on CNCs.