Conduction Channel Research Articles

Enhancing Supercapacitor Performance of NiCoMn‐Layered Double Hydroxide with Ag–Citrate/Polyaniline Nanocomposites

Layered double hydroxide (LDH) has a layered structure, which makes it a strong candidate for supercapacitors (SC) due to its high surface area. However, they suffer from low conductivity due to insufficient charge transfer across their layers. This research aims to overcome this obstacle by introducing conductive channels among the layers by the addition of Ag–citrate and polyaniline (PANI). Consequently, five electrodes (S1–5) were made from NiCoMn LDH (referred to as LDH henceforth) and 2:1 Ag–citrate and PANI composite (Ag/PANI) in different ratios and made into electrodes. Electrochemical analysis revealed successful improvement in the performance of LDH as the fraction of Ag/PANI increased until it equaled Ag/PANI where the highest specific capacitance of 617 F g−1 was obtained, which is 12% greater than the value for solely LDH electrode (550 F g−1). A device was fabricated with the best electrode (S3) and activated carbon electrode, which demonstrated energy densities and power densities of 41 WhKg−1 and 412.5 W Kg−1 and 14 WhKg−1and 8250 W Kg−1 at 0.5 and 10 A g−1 current densities, respectively. It also exhibited a capacitive retention of about 75% at 3000 galvanostatic charge–discharge cycles. These results encourage the use in of NiCoMn LDH, in a 1:1 ratio with Ag/PANI in SCs due to its remarkable performance.

Transport chirality generated by a tunable tilt of Weyl nodes in a van der Waals topological magnet.

Chirality - a characteristic handedness that distinguishes 'left' from 'right'-is a fundamental property of quantum particles under broken symmetry intimately connected to their spins. Chiral fermions have been identified in Weyl semimetals through their unique electrodynamics arising from 'axial' charge imbalance between pairs of chiral Weyl nodes-the topologically protected 'relativistic' crossings of electronic bands. Chiral magnetotransport phenomena critically depend on the details of electronic band structure. However, the putative emergence of chiral electronic channels through shape altering of Weyl nodes is yet to be revealed. Here, we detect chirality-endowed linear conduction channels promoted by a tilt of Weyl bands in inversion-symmetric Weyl ferromagnet MnSb2Te4. The tuning of Weyl nodes is controlled with ionic hydrogen, which heals the system's (Mn-Te) bond disorder and lowers the internode scattering. The reshaped Weyl states feature a doubled Curie temperature ≳50 K and a strong angular transport chirality synchronous with a rare field-antisymmetric longitudinal resistance-a low-field tunable 'chiral switch' that is rooted in the interplay of Berry curvature, chiral anomaly and a hydrogen-mediated form of Weyl nodes.

Temperature-Dependent Characterization of Long-Range Conduction in Conductive Protein Fibers of Cable Bacteria.

Multicellular cable bacteria display an exceptional form of biological conduction, channeling electric currents across centimeter distances through a regular network of protein fibers embedded in the cell envelope. The fiber conductivity is among the highest recorded for biomaterials, but the underlying mechanism of electron transport remains elusive. Here, we performed detailed characterization of the conductance from room temperature down to liquid helium temperature to attain insight into the mechanism of long-range conduction. A consistent behavior is seen within and across individual filaments. The conductance near room temperature reveals thermally activated behavior, yet with a low activation energy. At cryogenic temperatures, the conductance at moderate electric fields becomes virtually independent of temperature, suggesting that quantum vibrations couple to the charge transport through nuclear tunneling. Our data support an incoherent multistep hopping model within parallel conduction channels with a low activation energy and high transfer efficiency between hopping sites. This model explains the capacity of cable bacteria to transport electrons across centimeter-scale distances, thus illustrating how electric currents can be guided through extremely long supramolecular protein structures.

Native Cellular Membranes Facilitate Channel Activity of MscL by Enhancing Slow Collective Motions of Its Transmembrane Helices.

Mechanosensitive channels of large conductance (MscL) serve as a mechanoelectrical valve of cells in response to the membrane tension. The influence of membrane environments on the MscL channel activity and the underlying mechanism remains unclear. Herein, we developed a new sample preparation protocol that allows for the detection of high-quality 1H-detected solid-state NMR spectra of MscL in cellular membranes, enabling site-specific analysis of its dynamics. Dipolar order parameters and spin relaxation rates are measured for 51 residues of MscL in synthetic and native membranes. The dynamics data reveal that while MscL maintains a similar rigidity in both membrane environments, it exhibits enhanced slow collective motions in the native cellular membranes. Molecular dynamics simulations demonstrate the critical role of slow motions in the mechanosensitivity of MscL by promoting protein-membrane interactions. This study examines atomic-resolution dynamics of a membrane-protein in cellular membranes and provides novel insights into the functional significance of membrane-protein dynamics.

Novel Graphene‐Epoxy Composite with Aligned Architecture and Ultrahigh Thermal Conductivity

AbstractBecause of the surge in the power density of electronic devices, there is an urgent need for improvements in the thermal conductivity of packaging materials. Nowadays, epoxy composites supplemented with thermally conductive fillers are widely used for this purpose, but unfortunately, none of them can satisfactorily meet industrial requirements. Herein, this article reports on a novel method to prepare well‐shaped and highly ordered graphene‐epoxy composite architecture; that is, the epoxy infiltrates into tubular graphene columns that have been restored to the high thermally conductive structure of graphene. As a result, the newly developed graphene‐epoxy composite exhibits record‐high thermal conductivity of 69.74 W m−1 K−1 with filler content of only 11.22 wt.%. The unprecedentedly high thermal conductivity stems from the construction of thermally conductive channels and restoration of the inherent π–π conjugate structure of graphene. These findings not only offer a breakthrough in packaging materials with significantly enhanced thermal conductivity but also provide a promising avenue for the development of other advanced graphene‐added composites.

Sulfide/Polymer Composite Solid‐State Electrolytes for All‐Solid‐State Lithium Batteries

AbstractThis review introduces solid electrolytes based on sulfide/polymer composites which are used in all‐solid‐state lithium batteries, describing the use of polymers as plasticizer, the lithium‐ion conductive channel, the preparation methods of solid‐state electrolytes (SSEs), including dry methods and wet methods with their advantages and disadvantages. In addition, the physicochemical stability of sulfide/polymer composite based solid‐state electrolytes is analyzed. The sulfide/polymer composite based solid‐state electrolyte can be utilized in lithium metal or lithium sulfur batteries. However, there are still many problems left to be solved in practical applications of these solid‐state electrolytes. In this review, several solutions are explored. Firstly, the ultra‐long life cycle of batteries can be achieved by thinning the composite electrolyte. Secondly, when sulfur is applied as the positive electrode, the thinning electrolyte can reduce polarization and other problems. Finally, an integrated battery is employed to reduce the interface impedance. By addressing these aspects, the review aims to provide valuable insights into the future development of high‐performance solid‐state electrolytes in lithium battery technology.

Conduction channel creation by interstitial site engineering in otherwise insulating Na6ZnS4 for Na-conducting solid-state electrolytes

Na5.6Zn0.6Ga0.4S4, which retains the crystalline structure of its parent form Na6ZnS4, is described as a new class of Na-conducting solid-state electrolytes (SSEs) for all-solid-state batteries. We demonstrate that while Na6ZnS4 is ionically insulating (1.4 nS cm-1), Ga-substitution results in an astonishing improvement of ionic conductivity (σion) to 70.1 μS cm-1, making Na5.6Zn0.6Ga0.4S4 a practical SSE. This dramatic increase in σion (5 × 104 fold) is associated with an increased Na+ occupancy in interstitial sites as ‘x’ increases in Na6-xZn1-xGaxS4, where interstitial Na ions facilitate long-range Na+ conduction, which is otherwise immobile. Ga-substitution also results in phase-pure Na6-xZn1-xGaxS4, contributing at least partially to the enhancement of σion. Furthermore, Na6-xZn1-xGaxS4 exhibits neither releasing H2S gas nor compromising its crystalline structure for several hours under ambient conditions. Ga-substitution also enhances electrochemical stability. While the anodic limit remains largely unchanged, the cathodic limit is significantly lowered from 0.99 V vs. Na2Sn in Na6ZnS4 to 0.35 V in Na5.6Zn0.6Ga0.4S4, resulting in stable Na alloying/dealloying reactions in a symmetric Na2Sn ‖ Na2Sn cell. These findings are comprehensively supported by various experimental and theoretical methods. Finally, we construct a full cell (Na2Sn ‖ TiS2) and demonstrate the practicality of Na5.6Zn0.6Ga0.4S4 as a promising SSE in all solid-state Na ion batteries.

Preparation of high temperature proton exchange membrane through covalent organic framework doped polyvinylidene fluoride nanofibers

Covalent organic framework (COF) exhibits the great potential to promote proton conduction under low relative humidity for proton exchange membranes (PEMs). In this research, quick and stable proton conduction has been achieved since the prepared COF and polyvinylidene fluoride (PVDF) nanofibers are believed to constitute successive proton conduction channels. The PVDF-COF nanofibers membrane is prepared through the in-situ growth of COF along PVDF nanofibers. The fine compatibility can drive the stable combination of COF with the PVDF nanofibers in PVDF-COF nanofibers. Most importantly, the fibrous PVDF nanofibers accelerate proton conduction through confining the proton conduction pathways. Additionally, ionic liquids of 1-butyl-3-methylimidazolium chloride (BmimCl) and 1-butyl-3-methylimidazole hexafluorophosphate (BmimPF6) as proton conduction carriers have been introduced to accelerate proton conduction in the prepared PVDF-COF/BmimCl/PA and PVDF-COF/BmimPF6/PA membranes. Phosphoric acid (PA) molecules are combined by COF and ionic liquid cations with the formation of intermolecular hydrogen bonds. As a result, the PVDF-COF/BmimPF6/PA membrane exhibits the proton conductivity of (1.81 ± 0.07) × 10−1 S/cm at 160 °C. The long-term proton conductivity stability is determined, deriving from the proton conductivities of 1.77×10−2 S/cm at 80 °C and 1.42×10−2 S/cm at 110 °C in the 400 h non-stop measurement. The single fuel cell equipped with the PVDF-COF/BmimPF6/PA membrane represents the open circuit voltage of 0.927 V and the peak power density of 178.8 mW/cm2 at 100 °C, 0.907 V and 326.5 mW/cm2 at 120 °C.

Prospective assessment of risk factors for appropriate ICD intervention in patients with ischemic cardiomyopathy: results of PARCADIA trial

Abstract Background There is still a big unmet need for better risk stratification tools to identify patients at high risk for sudden cardiac death in the era of primary prevention ICD therapy. Scar burden on late gadolinium enhancement (LGE) cardiac magnetic resonance (CMR) imaging may be a risk marker for the prediction of ventricular arrhythmia in post-myocardial infarction (MI) patients. Purpose The aim of the PARCADIA trial was to assess whether scar characteristics, determined via LGE-CMR, or other baseline risk markers are associated with appropriate ICD therapy. Methods In this prospective, multi-center, clinical trial, we enrolled post-MI patients with an indication for de novo primary prevention ICD. Main exclusion criteria were indication for cardiac resynchronization therapy and NYHA class IV. Prior to the ICD implantation, LGE-CMR was performed to analyze the amount of scar tissue (LGE core mass + grey zone mass) and LV function / volumes. A 24h Holter recording was performed to collect information on potential triggers like premature ventricular beats (PVB) and sympathetic-vagal balance based on heart rate variability (HRV). Follow-ups were performed in-office every 6 months, including remote monitoring. Appropriate ICD therapy was used as primary endpoint and adjudicated by a clinical event committee. Results 199 patients were enrolled at 5 investigational sites in Europe. Patients mean age was 64.3 years, with a mean LVEF of 27.7 %, timing from the index MI was 9.1 years, and 42.7% received a primary PCI on index MI. After a median follow-up duration of 47.7 months, 23.1% of patients received appropriate ICD therapy. In 135 patients (67.8%), quality of LGE-CMR was sufficient for detailed analysis. The mean LGE core mass (20.5 vs. 19,7 g) and grey zone mass (10.5 vs. 11.4 g) was not different in patients with or without appropriate ICD therapy, also not when corrected for LV mass. However, LVEF (28.5 vs. 32.9 %) was lower, while diastolic myocardial mass (141 vs. 125 g), and end-diastolic volume (265.0 vs. 226.7 ml) were significantly higher in patients with appropriate ICD therapy. On 24h Holter the mean PVB burden (3695 vs. 1643 beats), and non-sustained ventricular tachycardia (12 vs. 0.9), were higher in patients with appropriate ICD therapy, while the HRV (96.1 vs. 113.1 SDNN) was lower. In univariate analysis the variables LVEF, timing to index MI, primary PCI on index MI, PVB burden and HRV appeared to be predictors for appropriate ICD intervention, while in multivariate analysis LVEF and PVB burden remained predictive. Conclusion In post-MI patients with appropriate ICD therapy, scar burden was not different from patients without appropriate ICD therapy. Only LVEF and PVB burden were independent predictors of increased arrhythmogenicity. Improved CMR analysis on scar characteristics (conduction channels) to identify potential arrhythmogenic regions might be the topic for future research.

An Investigation into the Behavior of Cathode and Anode Spots in a Welding Discharge

The effective development of modern welding technologies and the improvement of equipment and materials inevitably require deep theoretical knowledge about the physical phenomena occurring in the electric arc column and in the near-electrode region. However, there is still no convincing theoretical description of an arc discharge. This article demonstrates, through the generalization of known experimental facts and studies using a high-speed camera, that the conductive channel of an electric arc has a discrete structure, consisting of a set of thin channels through which the main discharge current passes. The cathode spot of an arc discharge is a highly heated and brightly glowing area on the cathode’s surface. Electron emission occurs from this region, which supports the discharge as well as the removal of the cathode material. We propose a new technique to study the reverse side of the cathode spot, revealing a structure consisting of individual cells or fragments of the cathode spot. For the first time, we present the anode spots captured by a high-speed camera. We carry out an analysis of the spots’ structure. We determine the parameters affecting the mobility of cathode and anode spots. We propose a hypothesis based on the obtained experimental facts about the heterogeneous structure of cathode and anode spots in an arc discharge and the existence of current filaments that affect the mobility of spots during arc combustion.

Role of Point Defects and Ion Intercalation in Two-Dimensional Multilayer Transition Metal Dichalcogenide Memristors.

Two-dimensional materials, in particular transition metal dichalcogenides (TMDs), have attracted a nascent interest in the implementation of memristive architectures. In addition to being functionally similar to synapses, their nanoscale footprint promises to achieve the high density of a biological neural network in the context of neuromorphic computing. However, in order to advance from the current exploratory phase and reach reliable and sound memristive performances, an understanding of the underlying physical mechanisms in TMD memristors seems imperative. Despite the distinctive transport medium inherent to multilayer TMDs, the memristance is routinely attributed to defects or metal atoms present in the system, with their precise contribution remaining elusive. Specifically, the role of intrinsic point defects in the formation of conductive channels, although shown for monolayer TMDs, is not conclusively studied for multilayer samples. In this work, using density functional theory (DFT) and nonequilibrium Green's function (NEGF) formalism, a systematic study is carried out to analyze the impact that defects and metal atoms produce on the out-of-plane conductivity of multilayer TMDs. MoS2, a representative of the 2H structural configuration, and PtS2, a representative of the 1T structure, the most common crystal arrangements among TMDs, are used for this analysis. It is found that the intrinsic sulfur vacancies, which are the dominant defects present in both TMDs, appear to be insufficient in causing resistive switching on the application of an external bias. The claim that the intrinsic point defects on their own can realize a valence change memory-type device by providing a controllable conductive channel through the van der Waals structure seems, according to our study, improbable. The presence of metallic atoms is demonstrated to be essential to trigger the memristive mechanism, emphasizing the proper choice of a metal electrode as being critical in the fabrication and optimization of memristors using TMDs.

Synergistic Dual-Cross-Linking Gelation: Exploring the Impact of Metal-Ligand Complexation on Ionogel Performance.

Owing to the growing interest in wearable ionotronics, the demand for ionogels with outstanding mechanical and electrochemical characteristics has increased dramatically. Nevertheless, it remains challenging to simultaneously enhance the mechanical robustness and conductivity of ionogels because of their trade-off relationship. In this work, we propose physically/chemically dual-cross-linked ionogels designed to improve the mechanical strength without reducing ionic conductivity by introducing metal-ligand complexation only within the physically cross-linked domains. In particular, the impact of metal-ligand complexation, a crucial parameter in this strategy, on ionogel performance is systematically examined using various metal ions. The mechanical resilience and thermal stability of ionogels are effectively enhanced with Co3+ having the highest coordination number, which can be explained by the highest metal-ligand complexation (i.e., chemical cross-linking) density. Additionally, there is no degradation in ionic conductivity when compared to the pristine ionogel because these complexations occur within physically cross-linking domains that are irrelevant to the ion conductive channels. The dual-cross-linked ionogels are successfully applied to alternating-current electroluminescent displays (ACEDs). Moreover, a versatile mixed-emitter strategy is suggested to improve practicality, enabling the realization of frequency-controlled multicolor ACEDs.

Conductance Channels in a Single-Entity Enzyme.

For a long time, the prevailing view in the scientific community was that proteins, being complex macromolecules composed of amino acid chains linked by peptide bonds, adopt folded structure with insulating or semiconducting properties, with high bandgaps. However, recent discoveries of unexpectedly high conductance levels, reaching values in the range of dozens of nanosiemens (nS) in proteins, have challenged this conventional understanding. In this study, we used scanning tunneling microscopy (STM) to explore the single-entity conductance properties of enzymatic channels, focusing on bilirubin oxidase (BOD) as a model metalloprotein. By immobilizing BOD on a conductive carbon surface, we discern its preferred orientation, facilitating the formation of electronic and ionic channels. These channels show efficient electron transport (ETp), with apparent conductance up to the 15 nS range. Notably, these conductance pathways are localized, minimizing electron transport barriers due to solvents and ions, underscoring BOD's redox versatility. Furthermore, electron transfer (ET) within the BOD occurs via preferential pathways. The alignment of the conductance channels with hydrophilicity maps, molecular vacancies, and regions accessible to electrolytes explains the observed conductance values. Additionally, BOD exhibits redox activity, with its active center playing a critical role in the ETp process. These findings significantly advance our understanding of the intricate mechanisms that govern ETp processes in proteins, offering new insights into the conductance of metalloproteins.

Transport in a Two-Channel Nanotransistor Device with Lateral Resonant Tunneling.

We study field effect nanotransistor devices in the Si/SiO2 material system which are based on lateral resonant tunneling between two parallel conduction channels. After introducing a simple piecewise linear potential model, we calculate the quantum transport properties in the R-matrix approach. In the transfer characteristics, we find a narrow resonant tunneling peak around zero control voltage. Such a narrow resonant tunneling peak allows one to switch the drain current with small control voltages, thus opening the way to low-energy applications. In contrast to similar double electron layer tunneling transistors that have been studied previously in III-V material systems with much larger channel lengths, the resonant tunneling peak in the drain current is found to persist at room temperature. We employ the R-matrix method in an effective approximation for planar systems and compare the analytical results with full numerical calculations. This provides a basic understanding of the inner processes pertaining to lateral tunneling transport.

Expression of the grapevine anion transporter ALMT2 in Arabidopsis root decreases shoot Cl-/NO3- ratio under salt stress.

Grapevines (Vitis vinifera, Vvi) are economically important crop plants which, when challenged with salt (NaCl) in soil and/or irrigation water, tend to accumulate Na+ and Cl- in aerial tissues impacting yield, and berry acceptability for winemaking. Grapevine (Vitis spp.) rootstocks vary in their capacity for shoot Cl- exclusion. Here, we characterise two putative anion transporter genes - Aluminium-activated Malate Transporter VviALMT2 and VviALMT8 - that were differentially expressed in the roots of efficient (140 Ruggeri) and inefficient (K51-40) Cl- excluding rootstocks, to explore their potential for impacting shoot Cl- exclusion. Using the Xenopus laevis oocyte expression system, VviALMT2 and VviALMT8 formed conductive channels that were highly permeable to NO3-, slightly-to-moderately permeable to other substrates including Cl- and malate, but impermeable to SO42-. RT-qPCR analyses revealed that VviALMT2 was more highly expressed in the root vasculature and up-regulated by high [NO3-] re-supply post starvation, while fluorescently tagged translational fusion VviALMT2 localised to the plasma membrane. As VviALMT8 showed no such features, we selected VviALMT2 as our salt exclusion candidate and assessed its function in planta. Expression of VviALMT2 in Arabidopsis thaliana root vasculature reduced shoot [Cl-]/[NO3-] after NaCl treatment, which suggests that VviALMT2 can be beneficial to plants under salt stress.

Effect of traps and conductive pathways on electron emission from copper broad-area composite emitters

This study investigates electron emission from copper broad-area emitters (CBAEs) and copper broad-area composite emitters (CBACEs) based on the principles of trapping and conductive pathways. Emission current measurements were conducted on two CBACEs, which consisted of copper coated with a 300–400 μm epoxy resin and subjected to high voltages up to 15 kV. The research specifically examines the ‘switch-on’ and collapse phenomena occurring within the epoxy layer. Field emission microscopy (FEM) was utilized in a high-vacuum environment ( 10−6 mbar) to observe these effects. A comprehensive model is developed to explain the formation of conductive pathways within the epoxy layer, allowing electrons transfer from traps to the surface. This model treats the composite emitter as a trap-rich capacitor. The study also clarifies the effects of trap density and epoxy layer thickness on the collapse process. To gain a deeper understanding of the model, changes in the I-V curve were examined. Simulations, scanning electron microscopy-energy dispersive x-ray spectroscopy (SEM-EDX) images, and Fourier transform infrared spectroscopy (FTIR) analysis were employed to understand the collapse mechanism of the epoxy collapse. Additionally, Nyquist and Cole–Cole plots were analyzed across frequencies ranging from 1 to 106 Hz before and after applying a high electric field on the samples, revealing changes in the capacitive component and the role of diodes in the formation of conductive channels.

High-performance proton exchange membrane derived from N-heterocycle poly(aryl ether sulfone)s with ether-free hydrophilic blocks and exhibiting good stability and proton-conducting performance

The trade-off issue between proton conduction properties and stability is a constraint on the commercial application of non-fluorinated proton exchange membranes for fuel cells. To alleviate the issue, the multi-block N-heterocycle poly(aryl ether sulfone)s with ether-free hydrophilic blocks (b-SPDPESs), which is composited by diphenyl sulfone moieties and biphthalazindione structures with dense pendant benzenesulfonic groups, are developed to prepare high-performance membranes. The self-assembly effect of block copolymers not only improves the membrane stability but also constructs regular proton conduction channels. Moreover, the conduction channel consists of hydrophilic blocks without ether bonds, which effectively improves the tolerance of the membrane to radicals. The hydrogen-bond network between sulfonic groups and N-heterocycles in the channel improves the proton conduction efficiency, inhibits the swelling of the membrane, and improves the stability of the membrane. As a result, the swelling degree of b-SPDPESs membrane is only 15.8 %, the proton conductivity is as high as 238 mS cm−1, the membrane aging broken time at 80 °C is between 4 and 6.6 h, and the fuel cells loading the membranes and feeding with hydrogen and air perform the max power density of between 0.65 and 1.25 W cm−2. Modulating the sequence structure of chains and constructing multiblock polymers containing ether-free N-heretrocyclic blocks with sulfonic groups improve the stability of membranes while ensuring their proton conductivity.

Design and analysis of central gate organic thin film transistor

Abstract This paper presents a novel central gate organic thin-film transistor (OTFT) with electrodes in top-bottom configuration and its comparative performance analysis with conventional single and dual gate OTFTs. The central gate OTFT is comprised of a single gate electrode configured to be the center thin film. A pair of identical dielectric layers viz. top dielectric layer and a bottom dielectric layer on both sides of gate electrode to facilitate the further deposition top and bottom organic semiconductor layer over them respectively. The organic semiconductor layers (OSC) are configured as top OSC layer and a bottom OSC to accommodate two independent conduction channels. The source and drain electrodes are also deposited in pairs in top and bottom configurations. Due to the subtle modifications in the architecture the resultant output drain current of the central gate (CG) OTFT has increased manifold. It has been found in the study that the CG OTFT produces 94%, 76.36%, 80.58% higher drain current than bottom gate bottom contact (BGBC), top gate bottom contact (TGBC) and bottom gate top contact (BGTC) OTFT respectively of similar size, operating under identical voltage regime. Similarly in the case of dual gate (DG) OTFT an improvement of 5.10% has been recorded without any additional gate electrode at the same operating voltages.

Field Ion Microscopy of Tungsten Nano-Tips Coated with Thin Layer of Epoxy Resin

This paper presents an analysis of the field ion emission mechanism of tungsten–epoxy nanocomposite emitters and compares their performance with that of tungsten nano-field emitters. The emission mechanism is described using the theory of induced conductive channels. Tungsten emitters with a radius of 70 nm were fabricated using electrochemical polishing and coated with a 20 nm epoxy resin layer. Characterization of the emitters, both before and after coating, was performed using electron microscopy and energy-dispersive X-ray spectroscopy (EDS). The Tungsten nanocomposite emitter was tested using a field ion microscope (FIM) in the voltage range of 0–15 kV. The FIM analyses revealed differences in the emission ion density distributions between the uncoated and coated emitters. The uncoated tungsten tips exhibited the expected crystalline surface atomic distribution in the FIM images, whereas the coated emitters displayed randomly distributed emission spots, indicating the formation of induced conductive channels within the resin layer. The atom probe results are consistent with the FIM findings, suggesting that the formation of conductive channels is more likely to occur in areas where the resin surface is irregular and exhibits protrusions. These findings highlight the distinct emission mechanisms of both emitter types.

Constructing house-of-cards-like networks with BNNS confined in interlocking Al2O3 platelet skeletons for thermally conductive epoxy composites

The construction of 3D filler networks is an effective strategy to improve the thermal conductivity of epoxy resins, yet it is still severely limited by the disconnection of conduction channels. In this contribution, an original interlocking hybrid skeleton with continuous conduction channels was developed by assembling BNNS into an in situ-formed interlocking Al2O3 platelet skeleton using commercial polyurethane as a template, where large intergranular contact areas of Al2O3 platelets were established by sintering to greatly decrease the contact thermal resistance. Besides, the interlocking Al2O3 skeleton coupled with BNNS under hydrogen bonding endowed further improvement of its thermal conductivity. The optimized Al2O3/BNNS/EP composite displayed an excellent thermal conductivity of 5.01 W/mK at 15.3 vol% of Al2O3 and 11.4 vol% of BNNS loading, far higher than that of neat epoxy resin by 1904.0 %. Meanwhile, the interlocking hybrid skeleton provided the epoxy resin with low dielectric loss, satisfactory thermal stability and flame retardancy.