Composite Films Research Articles

Enhanced charge storage in supercapacitors using carbon nanotubes and N-doped graphene quantum dots-modified (NiMn)Co2O4

The integration of ternary metal oxides into carbon materials is anticipated to significantly boost the electrochemical performance of supercapacitor electrodes. This article synthesized carbon nanotubes (CNT)/(NiMn)Co2O4 composite materials using a straightforward hydrothermal method and subsequently prepared composite thin films of CNT/P-(NiMn)Co2O4@NGQD by phosphating and incorporating nitrogen-doped graphene quantum dots (NGQD). These films served as the functional electrode material for supercapacitors, enhancing their performance capabilities. The specific capacity of CNT/P-(NiMn)Co2O4@NGQD was measured at 2172.0 F g−1 at a current density of 1 A g−1, maintaining a capacitance of 1954.0 F g−1 at 10 A g−1, thus demonstrating excellent rate performance. Electrochemical impedance spectroscopy (EIS) further revealed enhancements in electrolyte flow dynamics and capacitance behavior post-NGQD introduction. The energy density of the composite material reached 94.4 Wh kg−1 at power density of 800 W kg−1, demonstrating superior electrochemical performance. The enhancement in these electrochemical properties is attributed to the high specific surface area and active sites of CNT/P-(NiMn)Co2O4@NGQD films, along with the synergistic effects of NGQD and metal ions facilitating rapid electrons and charge transfer. This work provides new insights into developing high-performance supercapacitors.

Enhancing output performance of triboelectric nanogenerators with ZnFe2O4 nanoparticles in biodegradable polylactic acid for sustainable energy harvesting

ABSTRACT The development of triboelectric nanogenerators (TENGs) using sustainable materials addresses the global electronic waste issue. This research focuses on fabricating a TENG device with biodegradable polylactic acid (PLA) as the tribopositive material and polytetrafluoroethylene (PTFE) as the tribonegative material. ZnFe2O4 nanoparticles are incorporated into the PLA matrix to enhance surface charge density and synthesised via a simple combustion method. PLA-ZnFe2O4 composite films were prepared by solvent casting with varying nanofiller content (0.25, 0.45, 0.65, and 0.85 g). Prepared composites were characterised by Powder X-ray Diffraction (PXRD) for crystalline nature and phase purity, Fourier Transform Infrared Spectroscopy (FTIR) for vibrational analysis, and Scanning Electron Microscopy (SEM) for surface morphology. The inclusion of ZnFe2O4 nanoparticles improves TENG output performance, with a maximum output voltage of 18.4 V and a current of 1.57 µA observed for a PLA (poly(lactic acid)) composite with 39.39% nanoparticle content. Electrical studies on the optimised device show successful charging of various capacitors and powering 20 LEDs and a calculator. Body movements like walking and jumping were also tested to measure voltage and current outputs. These findings highlight new possibilities for developing smart, self-powered electronic devices.

Enhancing self-induced polarization of PVDF-based triboelectric film by P-doped g-C3N4 for ultrasensitive triboelectric pressure sensors

Progress in wearable energy devices has reached the point of popularity over a few decades, as reflected by the rise of numerous sensors and storage devices driven by the urgent need for Internet of Things (IoT) applications. Triboelectric sensor (TES), on the basis of triboelectric nanogenerators (TENGs), exhibits high sensitivity and stability for pressure detection. Maximizing the sensitivity of the TES hinges upon the triboelectric layer selection capable of harnessing triboelectrification and electrostatic induction. Among them, PVDF has gained attention owing to its exceptional flexibility and tribo-negativity. However, the multiphase of pristine PVDF poses challenges, limiting its potential for TES with higher sensitivity. Tackling this issue, herein, we introduced phosphorus-doped graphitic carbon nitride (PCN) into the PVDF films to achieve self-induced polarization to enhance the sensitivity of the triboelectric pressure sensor. Through a controlled annealing temperature, phosphorus atoms are incorporated into the g-C3N4 (CN) matrix, enhancing the electronegativity of PVDF/PCN composite film while inducing a polarized β crystal phase in PVDF, thereby enabling greater attraction of positive charges. Consequently, the triboelectric output with PVDF/PCN composite film exhibited a significant improvement compared to the pristine PVDF film, achieving over a 100 V increment and the ability to power more than 100 LEDs. Furthermore, for the pressure-sensing applications, the TES with flexible PVDF/PCN triboelectric film exhibits a pressure sensitivity of 1.48 V/kPa, which shows a threefold increase in sensitivity compared to the pristine PVDF film (0.51 V/kPa), suggesting their great potential in self-powered wearable pressure sensors.

Fabrication and thermomechanical property investigations of polypropylene/silica and polypropylene/modified silica composite films

In this study, we fabricated polypropylene/silica (PP/S) and polypropylene/modified silica (PP/MS) composite films using the extrusion technique, and characterized, and investigated their thermomechanical behaviors. The characterization of the neat materials and prepared composites was successfully conducted using some advanced spectroscopic techniques. The thermal stability and thermomechanical behaviors of the composites were investigated through thermogravimetry analysis (TGA) and dynamic mechanical analysis (DMA). The tensile tests revealed that the PP/MS composites exhibited the highest strength values, reaching 22.23 MPa with 1.0 % MS. Higher tensile strength was obtained with PP/MS composites compared to PP/S composites, proving the clear effect of the hexadecyltrimethylammonium bromide (HTAB) binder in the composition of the composites. The highest strength values obtained with the PP/S composites were 20.10 MPa at a ratio of 2.5 %.

Silane modified Cr2O3/polyimide nanocomposite films with excellent surface insulation performance for space applications

The exploration of deep space significantly increases the probability of spacecraft failures due to surface electrostatic discharge, which imposes higher vacuum insulation protection requirements on polyimide (PI), the external insulation material of spacecrafts. To address this challenge, this study proposes using silane coupling agent KH550 for organic grafting treatment of Cr2O3nanoparticles, which are then used to dope and modify PI to enhance the vacuum surface insulation of PI films. The KH550 grafting improves the interface strength between the fillers and the matrix, allowing the fillers to be uniformly dispersed in the matrix. Compared to pure PI films, the prepared PI-Cr2O3@KH550 composite films exhibit significantly enhanced vacuum surface flashover voltage, improved surface/volume resistivity, and dielectric properties. The results demonstrate that PI composite films with 0.8% by mass of Cr2O3@KH550 show the most notable performance improvement, with the DC flashover voltage and impulse flashover voltage in vacuum increasing by 20.7% and 27.8%, respectively. The doping of chromium oxide nanoparticles introduces more deep traps into the PI films and reduce the surface resistivity. The higher deep trap density inhibits charge migration, thereby alleviating secondary electron emission and surface electric field distortion. Simultaneously, the lower surface resistivity facilitates dissipating surface charges and improves the surface insulation. These findings are of significant reference value for promoting the enhancement of aerospace insulation performance.

Selecting a target for obtaining films of higher manganese silicide using magnetron sputtering

A film of manganese silicides on mica was obtained using a magnetron sputter from three types of targets. Microstructure and elemental composition of targets and films studied by scanning electron microscopy and electron reflection diffraction methods. The phase composition and texture of films by thickness (cross sections) were controlled by scanning and transmission electron microscopy. It has been shown that when depositing films from a poly- and single-crystalline target of higher manganese silicide, in contrast to a target of sintered Mn and Si powders, after successive annealing at a temperature of 800 K and a temperature of 10–3 Pa for 1 hour, polycrystalline films of higher silicide can be obtained. manganese composition Mn4Si7.

Preparation and Keep-Refreshing Effect of Chitosan/Sea Buckthorn Polysaccharide Composite Film on the Preservation of Yellow Cherry Tomatoes.

In this study, sea buckthorn polysaccharides (SBP) were added as functional substances to chitosan (CS), and chitosan/sea buckthorn polysaccharide (SCS) composite films were prepared using the casting method. The effects of SBP addition on the optical properties, physical properties, mechanical properties, structure, antioxidant activity, and antibacterial activity of the SCS composite films were studied, and the prepared SCS composite films were used to preserve yellow cherry tomatoes. The results showed that SCS composite films exhibited good UV resistance, water solubility, and antioxidant activity, but its apparent structure, hydrophobicity, and mechanical properties needed further improvement. Meanwhile, SBP has inhibitory effects on all 8 experimental strains. In addition, the SCS composite film with the addition of 200 mg/L SBP could reduce the weight loss rate of yellow cherry tomatoes, maintain hardness, delay the decrease of total soluble solids, titratable acid, and Vitamin C content, and inhibit the accumulation of malondialdehyde. SCS composite films are beneficial for enhancing the quality of yellow cherry tomatoes during storage, and their application in fruit and vegetable preservation has development prospects.

Self‐cleaning films of biopolymer polyhydroxybutyrate with different semiconductors incorporation: Development, characterization, and photocatalytic activity evaluation

AbstractSelf‐cleaning hydrophobic films were developed using polyhydroxybutyrate (PHB), enhanced with titanium dioxide (TiO2), bismuth oxyiodide (BiOI), and a BiOI/α‐Fe2O3 heterojunction. This is the first study to analyze the photoactivity of BiOI and BiOI/α‐Fe2O3 immobilized into PHB. Alternative solvents for dissolving PHB were investigated. Additionally, formation methods such as casting in Petri dishes, as well as controlled thickness casting through non‐solvent‐induced phase separation (NIPS), and evaporation‐induced phase separation (EIPS), were employed and compared. Despite differing morphologies, both NIPS and EIPS films exhibited similar photocatalytic activity, suggesting that only the catalyst on the external surface of the film is active. The highest pseudo first‐order apparent kinetic constant (0.1468 ± 0.0015 min−1 g−1) was found in films with the lowest polymer and catalyst concentrations analyzed (5% and 3% ). A double‐layer film preparation method was proposed to enhance photocatalytic activity, resulting in a 70% increase in the kinetic constant (0.2506 ± 0.0019 min−1 g−1). Double‐layer composite films with BiOI and BiOI/α‐Fe2O3 showed photocatalytic activity comparable to TiO2 under UV–visible light. Furthermore, their photocatalytic activity under visible light was confirmed, unlike TiO2, which exhibits a negligible kinetic constant in this wavelength range.

Anti-Oxidant and Anti-Bacterial Behavior of Sodium Alginate Patches Fortified with Polyurethane and Ag-MOF as Potential Future Wound Healing Material

ABSTRACT Sodium Alginate (SA) is a natural polysaccharide with a high degree of biocompatibility, biodegradability, water absorption properties and stiffness. The inherent brittleness of SA limits its applications in the field of wound healing. The blending of highly flexible polyurethane (PU) with SA could alter the nature of film. In addition, the incorporation of Ag-Metal Organic Framework (Ag-MOF) synthesized via the solvothermal method can help in the enhancement of stability and biological characteristics. The SA and its composite films were obtained through a feasible phase inversion technique. In addition, the Ag-MOF@SA/PU film demonstrates the strongest bacteriostatic impact on E. faecalis and P. aeruginosa, with percentages of approximately 96.9% and 96.41%, respectively. Furthermore, the film demonstrates a radical scavenging efficiency of 83.96%. Moreover, the Ag-MOF@SA/PU film exhibited a significant increase in the production of oxidative stress, attaining a value of 84.89%. Owing to the results, Ag-MOF@SA/PU was taken for in-vitro degradability analysis and visible surface erosion was observed over time. Thus, the Ag-MOF@SA/PU film could be considered for future wound healing therapy.

2D TMDC aging: a case study of monolayer WS2 and mitigation strategies.

Due to their unique properties, two-dimensional transition metal dichalcogenides (2D TMDCs) are considered for diverse applications in microelectronics, sensing, catalysis, to name a few. A common challenge in 2D TMDC research is the film's inherent instability i.e., spontaneous oxidation upon ambient exposure. The present study systematically explores the effect aging on the film composition and photoluminescent properties of monolayer WS2, synthetically grown by metal-organic chemical vapor deposition. The aging rate is investigated for different oxygen (i.e., O2 gas concentration and humidity) and light-controlled environments. Simple mitigation strategies that do not involve capping the 2D TMDC layer are discussed, and their effectiveness demonstrated by benchmarking the evolution in photoluminescence response against ambient exposed monolayer WS2. These results highlight the need to store 2D TMDCs in controlled environments to preserve the film quality and how future studies can account for the aging effect.

Cascaded dual-parameter SPR fiber sensor for RI and pH simultaneous detection based on Ag film and an Ag/self-assembled nanofilm structure

To achieve more accurate analysis and detection of changes in liquid parameters, we propose a dual-parameter surface plasmon resonance (SPR) sensor that can measure refractive index (RI) and pH simultaneously. In this paper, we compare and analyze the transmission spectrum when the SPR effect is excited by the cladding mode of a photonic crystal fiber (PCF) and the core mode of the no-core fiber. The results show that the SPR effect excited using the cladding mode is stronger and the sensor has better loss peaks, which is more conducive to realizing the detection of the external environment. Therefore, the sensor uses PCF as the substrate and utilizes a cascade composite film structure, and the area where a silver film is deposited on the surface of the PCF is selected as the RI sensing area. Another part of the PCF, after the silver film is deposited, uses a high-sensitivity polyacrylic acid/chitosan self-assembled nanofilm as the pH-sensitive film. Experimental results show that the maximum sensitivity is 4122.44 nm/RIU and -57.82 nm/pH when the RI range is between 1.333 and 1.385 and the pH range is between 3.11 and 8.63, respectively. In addition, we experimentally verified that the sensor had good stability and repeatability. The design of the sensor provides new possibilities for real-time monitoring and precise control, helping to advance scientific research and the development of industry.

Reconstruction and Solidification of Dion-Jacobson Perovskite Top and Buried Interfaces for Efficient and Stable Solar Cells.

Quasi-two-dimensional (Q-2D) perovskites show great potential in the field of photonic and optoelectronic device applications. However, defects and local lattice dislocation still limit performance and stability improvement by nonradiative recombination, unpreferred phase distribution, and unbonded amines. Here, a low-temperature synergistic strategy for both reconstructing and solidifying the perovskite top and buried interface is developed. By post-treating the 1,4-phenylenedimethanammonium (PDMA) based (PDMA)MA4Pb5I16 films with cesium acetate (CsAc) before thermal annealing, a condensation reaction between R-COO- and -NH2 and ion exchange between Cs+ and MA+ occur. It converts the unbonded amines to amides and passivates uncoordinated Pb2+. Meanwhile, it adjusts film composition and improves the phase distribution without changing the out-of-plane grain orientation. Consequently, performance of 18.1% and much-enhanced stability (e.g., stability for photo-oxygen increased over 10 times, light-thermal for T90 over 4 times, and reverse bias over 3 times) of (PDMA)MA4Pb5I16 perovskite solar cells are demonstrated.

Wireless and Opto-Stimulated Flexible Implants: Artificial Retina Constructed by Ferroelectric BiFeO3-BaTiO3/P(VDF-TrFE) Composites.

The degeneration of retinal photoreceptors is one of the primary causes of blindness, and the implantation of retinal prostheses offers hope for vision restoration in individuals who are completely blind. Flexible bioelectronic devices present a promising avenue for the next generation of retinal prostheses owing to their soft mechanical properties and tissue friendliness. In this study, we developed flexible composite films of ferroelectric BiFeO3-BaTiO3 (BFO-BTO) particles synthesized by the hydrothermal method and ferroelectric poly(vinyldene difluoride-trifluoroethylene) (P(VDF-TrFE)) polymer and investigated their applications in artificial retinas. Owing to the coupling of the photothermal effect of BFO-BTO particles and the pyroelectric effect of the P(VDF-TrFE) polymer, the composite films demonstrate a strong photoelectric response (a maximum peak-to-peak photovoltage > 80 V under blue light of 100 mW/cm2) in a wide wavelength range of light (from visible to infrared) with the inherent flexibility and ease of preparation, making it an attractive candidate for artificial retinal applications. Experimental results showed that blind rats implanted with artificial retinas of the composites display light-responsive behavior, showcasing the effectiveness of vision restoration. This study demonstrates a novel approach for employing ferroelectric materials in vision restoration and offers insights into future artificial retina design.

The Method That Makes Oils and Fats Healthier: Interesterification

Lipids, which provide various additives to the food industry, are developed with various modification techniques. In addition to hydrogenation and fractionation techniques, interesterification has become widespread in recent years. This technique, which has been used for more than a century, is classified as chemical or enzymatic interesterification, depending on the use of metal alcoholate or enzyme as a catalyst during the redistribution of fatty acids in the triglyceride ester on glycerol. Since the partial hydrogenation technique has been abandoned due to the formation of trans fatty acid, interesterification is carried out in the production of trans fat-free oil, in the production of breast milk substitutes, in the optimization of cocoa butter substitutes and equivalents, in the formation of structured lipids with nutritional advantages and in the lipid composition in the edible film. With its expanding area of use, its effect on health has been investigated, and the information obtained from studies on humans is that it does not have a negative effect. However, more work is needed on this subject. On the other hand, the World Health Organization recommends consumption of interesterified fats in order to reduce trans fat consumption. The objective of this review was to gather information about interesterification which has become widespread in the oil industry and has been used in new products. The outcome of this study could help better understanding and utilization of interesterification for future research and applications.

Microwave reflective properties of amorphous nanogranular composites (CoTaNb)x(MgO)1-x

The most important task of flexible and stretchable electronics is to modify the structure in nanoheterogeneous metal-dielectric media to control the properties of materials and create new small-sized devices based on them. In this paper, we present the results of experimental studies of the structure and microwave reflective properties in the frequency range of 8–12 GHz of amorphous nanogranulated composites (CoTaNb)x(MgO)1−x, 21.73 ≤ x ≤ 73.27 at.% with a thickness of 311–1040 nm. Niobium and tantalum, which are part of the metal alloy, are the most promising metals used in aircraft and rocket engineering, as well as in radio electronics and microprocessor technology, for example, as capacitors. The AFM method revealed a granular structure with a granule size from 70 to 200 nm at a metal alloy content of up to 51.70 at.%. The spectra of the microwave reflectivity as a function of frequency, the dependence of the reflectivity on the metallic phase content and the effective thickness of the composite layer are obtained. It is shown that a significant increase in the microwave reflectivity and its saturation are determined to a greater extent by the metallic phase content than by the effective layer thickness. The results of the experimental effect of magnetic fields with induction up to 0.3 T on the microwave reflectivity of composite films are presented. It is shown that magnetic fields can most effectively change the reflective properties of composites (from 8 % to 29 %) at the extremes of the microwave reflectivity of films with the lowest metallic phase content of 22.61–21.73 at.%. With an increase in the metallic phase content, the maximum change in the microwave reflectivity decreases exponentially.

Enhanced antibacterial photodynamic therapy with Qu/Ce6@ZIF-8 nanoplatform for Staphylococcus aureus control in food preservation

Antimicrobial Photodynamic Therapy (aPDT) effectively combats Staphylococcus aureus (S. aureus) infections and mitigates antibiotic resistance. However, the application of aPDT is constrained by challenges related to photosensitizers, such as poor water solubility, a tendency to aggregate, and low bioavailability. In response, we have developed a nanoplatform using ZIF-8 nanocomposites. Through in-situ synthesis, we incorporated the chlorin e6 (Ce6) into the ZIF-8 matrix based on competitive coordination strategy, significantly enhancing its photocatalytic activity. The bioactivity of quercetin (Qu), through competitive inhibition of Sortase A (SrtA), enhances bacterial cell membrane permeability, thereby boosting the efficacy of the Qu/Ce6@ZIF-8 nanoparticles. This dual antibacterial strategy markedly suppresses S. aureus growth (MIC = 150 μg/mL). Moreover, we have engineered a polycaprolactone (PCL) composite film embedding these nanoparticles, which, under red light irradiation, substantially inhibits S. aureus proliferation on chilled chicken surfaces, thus extending shelf life to eight days. This innovative approach offers a promising strategy for antimicrobial food preservation, employing a multifunctional nano-antibacterial platform.

Improving mango shelf-life using PVA composite films prepared with Zn-doped carbon quantum dots derived from crayfish shells

Food packaging plays a vital role in preserving various agricultural and food commodities for postharvest management. This study aimed to investigate postharvest preservation technologies for mangoes using composite films made from polyvinyl alcohol (PVA) and Zn-doped carbon quantum dots (Zn-CQDs). The results showed a marked increase in the antibacterial potential of the composite films after Zn doping. Furthermore, the addition of Zn-CQDs significantly improved the mechanical properties, thermal stability and ultraviolet absorption of the Zn-CQDs/PVA composite films. In addition, the mango preservation experiment demonstrated that the 5% Zn-CQDs/PVA composite film was effective in delaying the decline in mango hardness (the composite film group was 63.2% higher than the control), VC content (the composite film group was 27.5% higher than the control), titratable acid content (the composite film group was 149% higher than the control), and the incline of disease index (the composite film group was 23.1% lower than the control), total soluble solids (the composite film group was 27.3% lower than the control), and weight loss rate (the composite film group was 25.7% lower than the control). These findings suggest that the Zn-CQDs/PVA composite films hold great potential as a new type of active packaging in the food industry.

Sandwich-Structured Carbon Nanotube Composite Films for Multifunctional Sensing and Electrothermal Application.

Electro-conductive films with excellent flexibility and thermal behavior have great potential in the fields of wearable electronics, artificial muscle, and soft robotics. Herein, we report a super-elastic and electro-conductive composite film with a sandwich structure. The composite film was constructed by spraying Polyvinyl alcohol (PVA) polymers onto a buckled conductive carbon nanotube-polydimethylsiloxane (CNTs-PDMS) composite film. In this system, the PVA and PDMS provide water sensing and stretchability, while the coiled CNT film offers sufficient conductivity. Notably, the composite film possesses high stretchability (205%), exceptional compression sensing ability, humility sensing ability, and remarkable electrical stability under various deformations. The produced CNT composite film exhibited deformation (bending/twisting) and high electro-heating performance (108 °C) at a low driving voltage of 2 V. The developed CNT composite film, together with its exceptional sensing and electrothermal performance, provides the material with promising prospects for practical applications in wearable electronics.

Synchronously enhanced breakdown strength and energy storage ability of cellulose acetate flexible films via introducing ultra-low content of carbonized polymer dots

Developing green and environmentally friendly biomass materials for energy storage and application is of great significance to sustainable development. Novel composite films containing cellulose acetate (CA) and carbonized polymer dots (CPDs) are reported herein. The CPDs have strong hydrogen bonding interactions with CA matrix, in which CPDs act as the physical crosslinking points and enhance the entanglement density of the matrix. And the composite films demonstrate a significant enhancement in breakdown strength (Eb), reaching up to 520.58 MV/m with the addition of 0.1 wt% CPDs (1.62 times higher than 321.94 MV/m of pure CA). Furthermore, the discharging energy density (Ud) achieves 2.55 J/cm3 at 450 MV/m, which is 1.36 times higher than that of the pure CA film (1.87 J/cm3 at 400 MV/m) and simultaneously, the energy efficiency (η) is maintained at 73.3 %. The Coulomb-blockade effect induced by the ultra-low content of CPDs effectively inhibiting carrier migration, and the enhanced entanglement density of the matrix improving mechanical properties and reducing polarization loss, mainly contribute to the enhanced dielectric performances. Furthermore, CPDs also improve the mechanical properties of the composite films apparently. This work provides some references for the fabrication of the next generation of environmentally friendly dielectric composite films.

Green synthesized CeO2 nanoparticles-based chitosan/PVA composite films: Enhanced antimicrobial activities and mechanical properties for edible berry tomato preservation.

The current study is intended to enhance unique bioactive and eco-friendly composite films following a simple solvent-casting approach by incorporating cerium oxide nanoparticles (CeO2 NPs) with a chitosan (CS)/polyvinyl alcohol (PVA) matrix. Antimicrobial activity, preservation impact, mechanisms for the edible berry tomatoes and physicochemical properties of the produced films were tested. FTIR, SEM-EDX, XRD, UV–vis spectroscopy and contact angle were used to characterize the films. Incorporated (3.0 wt%) CeO2 NPs practically developed composite film's thermal stability, structural, mechanical, bioactive, antioxidant, barrier and wettability properties. The tomatoes' look, weight loss and stiffness were better preserved after 25 days of storage at room temperature (25 ± 5 °C) when 3.0 wt% CeO2 NPs films were used instead of the original CS/PVA film. CS and CeO2 NPs have unique physiochemical and antibacterial properties. Food packaging extensively investigates the modified films as antimicrobials and preservatives to increase the shelf life of packaged foods, owing to their ability to inhibit gram-positive bacteria (Bacillus cereus and Staphylococcus aureus), gram-negative bacteria (Klebsiella pneumoniae and Pseudomonas aeruginosa), and filamentous fungi (Bipolaris sorokiniana, Fusarium op., and Alternaria sp.). Our findings indicated that the CeO2/CS/PVA composite films could be used as effective wrapping materials for food preservation.