Conduction Channel Research Articles

Effect of graphene sheet diameter on the microstructure and properties of copper-plated graphene-reinforced 6061-aluminum matrix composites

Herein, graphene with two different average sheet diameters was ultrasonically dispersed, mechanically stirred, and copper-plated. The pretreated graphene was mixed with 6061-aluminum (6061Al) powder to fabricate copper-plated graphene (0.5 wt%) reinforced 6061Al matrix composites by spark plasma sintering. The resulting composites were characterized in terms of their microstructure, tensile properties, electrical conductivity, and thermal conductivity. The incorporation of graphene facilitated load transfer and hindered dislocation movement, thereby enhancing the mechanical properties of the composites. Notably, the composite reinforced by larger-sized graphene achieved a favorable combination of high tensile strength (218 MPa) and fracture strain (17.2 %). Moreover, the addition of graphene also ameliorated the electrical conductivity of 6061Al. The composite reinforced by the larger-sized graphene achieved the highest electrical conductivity of 47.7 %IACS, attributed to the formation of a wider range of conductive channels. Additionally, the introduction of larger-sized graphene increased the thermal conductivity of 6061Al from 161.4 W/(m·K) to 183.2 W/(m·K), whilst the smaller-sized graphene contributed to a modest enhancement of 15.3 W/(m·K). In conclusion, graphene with a larger sheet diameter exhibits a remarkable reinforcement effect on the overall performance of 6061Al.

Effect of SiO2 Surface Passivation on the Performance of GaN Polarization Superjunction Heterojunction Field Effect Transistors

In this article, the effects of the SiO2 surface passivation layer are reported on normally‐on 1.2 kV GaN polarization superjunction (PSJ) heterojunction field effect transistors (HFETs) by comparing the electrical performances of PSJ HFETs with and without SiO2 surface passivation. A slight recovery of the 2D electron gas sheet density is observed in the slight negative shift of Vth after SiO2 surface passivation. Passivation also increases the breakdown voltage. This improvement may result from removing positive surface charges in defects along the P‐GaN gate sidewall and top u‐GaN layer after the specifically designed SiO2 surface passivation. Furthermore, the SiO2 surface passivation can also effectively suppress the surface gate leakage currents in the PSJ HFETs by eliminating the conductive channel created by the positive surface charges in defects.

HfO2-Based RRAM with In Situ Conductive Channels Induced by Nanoparticles to Improve Stability

HfO₂-Based RRAM with In Situ Conductive Channels Induced by Nanoparticles to Improve Stability

Fe2O3 Embedded in N-Doped Porous Carbon Derived from Hemin Loaded on Active Carbon for Supercapacitors.

The high power density and long cyclic stability of N-doped carbon make it an attractive material for supercapacitor electrodes. Nevertheless, its low energy density limits its practical application. To solve the above issues, Fe2O3 embedded in N-doped porous carbon (Fe2O3/N-PC) was designed by pyrolyzing Hemin/activated carbon (Hemin/AC) composites. A porous structure allows rapid diffusion of electrons and ions during charge-discharge due to its large surface area and conductive channels. The redox reactions of Fe2O3 particles and N heteroatoms contribute to pseudocapacitance, which greatly enhances the supercapacitive performance. Fe2O3/N-PC showed a superior capacitance of 290.3 F g-1 at 1 A g-1 with 93.1% capacity retention after 10,000 charge-discharge cycles. Eventually, a high energy density of 37.6 Wh kg-1 at a power density of 1.6 kW kg-1 could be delivered with a solid symmetric device.

Sn–3Ag–0.5Cu/TiO2/Ti wire-tube structure with memristive response by ultrasonic soldering

High-performance memristors have become the next generation of memory devices with potential application to ultra-high-speed, large-capacity, high-density computing requirements. However, devices with low operating voltage, high switching ratio, and long cycle life have not yet been achieved. A novel Sn–3Ag–0.5Cu/TiO2/Ti wire-tube memristor was fabricated using ultrasonic soldering. Ultrasound application changes the wetting conditions of the filler by using the instantaneous high temperature and pressure generated by ultrasonic cavitation, which induces Sn–3Ag–0.5Cu filler metal into anodized TiO2 nanotubes to prepare a wire-tube structure. The Sn–3Ag–0.5Cu/TiO2/Ti device showed bipolar hysteresis with a clear storage window. The maximum switching ratio was 33, which is slightly lower than the value of 36 for a Ag/TiO2/Ti device made using a conventional anodizing method. Seventeen cycles were achieved, which is 143% higher that of the Ag/TiO2/Ti device. The operating voltage of the Cu–3Ag–0.5Cu/TiO2/Ti device was significantly lower than that of the Ag/TiO2/Ti device. The structure and electrochemical performance of the device was evaluated by Raman spectrometry (LAMAN), X-ray photoelectron spectroscopy (XPS) and Electrochemical impendence spectroscopy (EIS) analysis. Formation of the conductive channels of the TiO2 wire-tube structure memristor was studied using transmission electron microscopy and high-resolution transmission electron microscopy, and a model of the mechanism of formation of the conductive filaments was established.

Enabling high-temperature application of Nafion membrane via imitating ionic clusters in proton conduction channels

Nafion membranes, representative of perfluorosulfonic acid (PFSA) proton exchange membranes are not effective in dehydrated state and high-temperature condition (>100 oC). The traditional hybrid modification would lower the mechanical strength of the membrane due to the large-scale phase separation. In this work, a hyperbranched polyamide (HBM) featuring high sulfonate concentration and nanoparticle morphology is synthesized and non-destructively filled into Nafion matrix to imitate the “ionic cluster” to accelerate the proton conduction at elevated temperature. During the non-destructively membrane modification, the Nafion PFSA membrane is swelled in the solution and the main chain structure is expanded, the HBM macromolecules is simultaneously filled into the membrane together with the solvent. After the removal of solvent, HBM end-capped with –COOH forms strong hydrogen bonds with the sulfonate groups in Nafion matrix. As a result, proton conductivity of the composite membrane can reach 0.047 S/cm, which is 1.9 times higher than that of the pristine Nafion membrane, at 110 oC and 60% RH. Given the excellent overall stability, fuel cell performance of the HBM-modified Nafion membrane is studied and a 30% increase in power density is observed, suggesting a viable strategy to expand the operation temperature of PFSA-based fuel cells.

Mns-MWCNT Composite, as a Superior Electrode Material for Asymmetric Flexible Quasi Solid-State Supercapacitors

Nowadays, renewable and sustainable energy sources are being explored and promoted to curb global pollution and to solve the issue of depleting fossil fuel resources. However, these renewable energy sources are intermittent in supply, therefore, it becomes necessary to store them for future usage. The traditional storage devices for electrical energy storage are different kinds of batteries but the sluggish performance of batteries, use of toxic heavy metals, issues pertaining to safety and low cycling efficiency are some of its major drawbacks. Recent proliferation of portable, wearable and flexible electronics and adoption of electric vehicles have forced the scientists to look for fast charging, light weight, leak proof, safe, toxic material free, durable energy storage devices like supercapacitors. Supercapacitors possess fast charge-discharge characteristics, high cycling stability and eco-friendliness in comparison to batteries. But they suffer from extremely low energy density (<10 Wh kg-1), high cost, bulk size, high self-discharge and significant drop in power density while increasing its energy density. The rational synthesis of electrode-materials has a significant impact on the development of high-performance electrodes for energy storage devices. Traditionally semiconducting materials like transition metal oxides are used as pseudocapacitive materials but transition metal oxides have very low electronic and ionic conductivity. Recently, transition metal sulfides, another class of semiconductors, are being investigated as they exhibit better conductivity and reaction kinetics compared to oxides. In this work, α-MnS is selected as an alternative to transition metal oxides. α-MnS is the most stable polymorph among other possible crystal structures of MnS, and has a hexagonal sheet like structure along with high operational potential window than many other metal sulfides. Although it is more conducting than transition metal oxides, it still needs conductivity enhancers like activated carbon, graphene, multiwall carbon nanotubes (MWCNT) etc. External mixing of conductivity enhancers is not effective enough to enhance the conductivity. Hence, MWCNT is mixed during the synthesis step to have a better bonding with α-MnS and create high conductivity channels. α-MnS + MWCNT composite shows a specific capacitance of 115 F g-1 at 1 A g-1 in 3 M KOH electrolyte under 3 electrode configuration. α-MnS + MWCNT composite is deposited on flexible conducting carbon cloth as cathode material and Vulcan carbon is deposited on carbon cloth as anode material. A mixture of poly vinyl alcohol PVA+ 3 M KOH is used as the gel type electrolyte. X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), cyclic voltammetry (CV), galvanostatic charge discharge (GCD), electrochemical impedance spectroscopy (EIS), cycling stability are performed to characterize the active material and the device performance. The assembled device shows a potential window of 1.4 V, alongside a specific capacitance of 27.7 F g-1 at 1 A g-1 and with 80% of capacity retention after 10,000 cycles. These results prove that transition metal sulfides can be viable alternative materials for supercapacitor application. This quasi-solid state or gel type electrolyte significantly reduces the conductivity and specific capacitance. Enhancing the ionic conductivity of the gel and finding out the optimum thickness of gel electrolyte layer between the electrodes are expected to open new pathways in enhancing the performance of the device. Figure 1

Non-destructively incorporating ceria in Nafion membrane as hydroxyl radical scavenging agent for long-term PEMFC application

Aiming at enhancing the long-term operation of proton exchange membrane fuel cell (PEMFC), Nafion as a typical example of perfluorosulfonic acid proton exchange membrane is non-destructively modified by sulfonated ceria (CeO2-DS) nanoparticles via a swelling-filling strategy. CeO2-DS nanoparticles in Nafion matrix can not only act as radical scavenging agent to improve the durability of Nafion, but also assist the re-construction of the efficient proton conduction channel in the composite Nafion membrane. Both oxidative stability and proton conductivity of the Nafion membrane are therefore remarkably improved with the great mechanical and thermal stability of Nafion maintained. PEMFC equipped with the modified Nafion membrane therefore outperforms that with the pristine Nafion membrane in terms of both power output and durability. Specifically, the maximum power density of the PEMFC equipped with modified Nafion after Fenton accelerated degradation test was significantly improved by ca. 25 % compared with that of the pristine Nafion membrane. This work hence provides a facile way to improve the durability of the PEMFC for practical applications.

(Invited) GaN Photoconductive Semiconductor Switches for Efficient High-Voltage Power Conversion Applications

Gallium nitride (GaN) photoconductive switch (PCSS) technology can revolutionize high-voltage, efficient power-switching capabilities. PCSSs are optically driven, which advantageously isolates sensitive control circuitry from electromagnetic interference (EMI) resulting from rapidly switching high voltages and currents (high dI/dt or dV/dt). Fast switching times and extremely low on-resistances are achievable in PCSSs. The conductive channel region during on-state (under illumination) also serves as the voltage hold-off region in the off-state (dark) and does not require an additional drift layer that limits conventional unipolar device performance. In addition, the on-state resistivity can be further reduced by increasing the driving optical power density. Carbon-doped GaN (GaN:C) can result in extremely low dark currents, high blocking voltages, as well as support very low on-resistances.Lateral and vertical GaN PCSSs are fabricated. Lateral GaN:C PCSS structures consist of a 4 µm thick GaN:C layer grown by metal organic chemical vapor deposition (MOCVD) on a SiC substrate. Vertical GaN:C PCSS structures consist of a 100 µm thick GaN:C layer grown by hydrive vapor phase epitaxy (HVPE) on a native GaN substrate. Contacts were formed by evaporation of Ti/Au (25 nm /250 nm). The PCSS devices are driven with a 3 W commercial off-the-shelf (COTS) ultraviolet (UV) light emitting diode (LED) with peak output at 365 nm and a 10 nm full width half maximum.Vertical GaN PCSSs demonstrate exceptional on-state characteristics with an on-state current density of ~150A/cm2 , or an on-state resistivity of 66 mΩ-cm2. The off-state (dark) blocking capability exceeds 1 kV (maximum value tested). The transient switching characteristics of GaN:C PCSS will be characterized, and discussion will be provided relating to device design and optical driving conditions, including GaN:C carbon doping density, GaN:C layer thickness considerations, design for reduced contact resistance, illumination power density, and illumination wavelength.

Anion Exchange Membrane Using Fused Expanded Pyridinium As Their Cationic Unit

Ion conductivity is expressed as a function of the Faraday constant, ion concentration, and mobility. Thus, an increase in both ion concentration and mobility is crucial for increasing the ion conductivity. Ion mobility reflects ionic motion in the restricted area of ion conduction channels. The general approach to expand ion conduction channels in AEM is to introduce a large number of ionic groups, i.e., to increase ion-exchange capacity (IEC). Because the increase of IEC also increase ion concentration, increase of IEC have been major strategy for increasing ion conductivity. However, this approach causes softening of the AEM because high IEC involves large amount of water uptake (WU).On the other hand, the ion concentration in AEM is also affected by the dissociation constant of the ionic groups. However, conventional ionic groups in AEMs, such as ammonium cations, suffer from a low dissociation constant that leads to low ion conduction in AEM. Previously, we found that a fused expanded pyridinium cation (FEP) having a delocalized positive charge showed high dissociation of OH– owing to the weak interaction between the soft acid (FEP) and the hard base (OH–) which can be explained based on the Pearson Hard Soft Acid Base (HSAB) principle. As the result, AEM with FEP unit exhibited excellent ion conductivity of 123.4 ±13.3 mS cm–1 at 80 °C with very low IEC (0.77 mmol g-1).Recently, we synthesized alkylated fused expanded pyridinium (CxFEP) with alkyl chain lengths (x) of 0, 6, 12, and 18 and introduced into polymers as side chains for AEM applications. FEP is characterized by a large π cation that offers weak electrostatic interactions with anions such as hydroxide (OH–) ions and therefore leads to high OH– conductivity in AEM. CxFEP shows synergetic effect between the π-π interactions of FEP and van der Waals interactions of the alkyl chains and forms a strong assembly, particularly for C6FEP. On the other hand, when CxFEP was introduced into the polymers, C12FEP formed an ordered stacking assembly in the films, whereas the other polymers with shorter (C0 and C6) and longer (C18) alkyl chains exhibited no such ordered structure. For the AEM, all the polymers showed higher ion conductivities than that of commercial ammonium-based AEM, even with their low ion exchange capacities (IEC), probably because of their characteristic weak interactions between the FEP cation and OH–. In particular, the AEM with C12FEP showed the highest ion conductivity of 143.3 ± 27.3 mS cm-1 even with a very low IEC of 0.41 mmol g-1. In addition to the high ion dissociation of FEP, the molecular assembly of FEP provides ionic conduction paths. This study demonstrates the importance of high ion dissociation and formation of a conduction pathway for AEM with high conductivity.

Dark Current Mechanisms and Suppression Strategies for Infrared Photodetectors Based on Two‐Dimensional Materials

AbstractNarrow‐bandgap 2D materials and semimetals, for example, graphene, black phosphorus (BP), tellurium (Te), and some novel transition metal dichalcogenides (TMDs), have been demonstrated to be promising building blocks for constructing next‐generation state‐of‐the‐art infrared (IR) photodetectors. However, these devices suffer from a significant dark current, primarily attributed to the intrinsic thermal excitation‐induced high carrier concentration. Suppressing the dark current is an essential issue in pursuing higher specific detectivity of IR photodetectors. Here, the authors demonstrate recent advances in suppressing dark current for 2D IR photodetectors. First, a brief insight into the dark current composition and mechanisms of 2D IR photodetectors is illustrated. Then, the varied band alignment for blocking dark current by the interfacial barrier is discussed. Next, localized electric field modulation by applying a gate voltage and ferroelectric materials is discussed. This method can effectively tune the concentration and distribution of carriers in the device conductive channel. Following that, interfacial engineering is summarized, by which interfacial defects can be passivated and interlayer defect‐induced dark current can be suppressed. Finally, the challenges and an outlook are delivered for developing state‐of‐the‐art IR photodetectors.

Aligning TiO2 nanofiber for high ionic conductivity in cellulose acetate gel electrolytes

The escalating need for sustainable energy storage systems has prompted enhanced investigations into the advancement of environmentally acceptable, flame-retardant, and high-performing polymer gel electrolytes. The present study examines the ionic conductivity and electrochemical characteristics of gel polymer electrolytes (GPEs) based on cellulose acetate (CA) incorporated with disordered and electric-field-induced aligned TiO2 nanofibers. The results of our study indicate that the arrangement of nanofibers within the CA matrix significantly affects the electrical properties of these electrolytes. The highest ionic conductivity of GPEs containing randomly distributed nanofibers is 5.48 × 10−4 S/cm when the nanofiber content is 2.5 wt%. On the other hand, 2.5 wt% aligned nanofibers containing GPE shows a slightly higher room temperature ionic conductivity of 6.2 × 10−4 S/cm. Nevertheless, the alignment of these nanofibers strategically leads to a gradual enhancement in ionic conductivity, ultimately reaching its maximum value of 5.99 × 10−3 S/cm at a concentration of 10 wt% at room temperature. Significantly, the level of conductivity exhibited in this case is more than 1.5 orders higher than the conductivity observed in disordered nanofiber dispersion within the CA matrix. The improved performance can be due to the creation of long-distance conduction channels enabled by the alignment of nanofibers. The incorporation of well-aligned nanofibers into GPEs results in a high Li+ ion transference number of 0.71, an excellent electrochemical stability window of 4.9 V, and exceptional interfacial compatibility with metal electrodes. In addition, the polymer electrolytes exhibit improved flame-retardant properties when 10 wt% aligned nanofibers are added, enabling the samples to endure exposure to a flame for a period of 10 s. These results indicate the potential suitability of the nanocomposite gel polymer electrolytes (NCGPEs) for application in future advanced energy-storing systems. XRD, FTIR, and XPS investigations further confirm the ion-conduction features of the produced NCGPEs. The investigation of increased electrical characteristics of NCGPEs was supported by a detailed computer simulation conducted using density functional theory (DFT).

Blooming flower like BiOBr decorated RGO nanocomposite as advanced electrode material for high performance supercapattery applications

The present work deals with a synthesis and characterization of bismuth oxybromide decorated reduced graphene oxide (BiOBr/RGO) nanocomposite as working electrode for supercapattery applications. where solvothermal method was adopted for the preparation of BiOBr/RGO nanocomposite. The prepared BiOBr depicts blooming flower-like microspheres and the presence of voids between petals could enable more adsorption of electrolyte ions and also act as conductive channels for easy ion diffusion. Further, the addition of GO with BiOBr resulted in an unfurling flower like morphology for BiOBr/RGO nanocomposite. The BiOBr/RGO (BiOBr – 3 wt% of GO) nanocomposite exhibits supreme specific capacity (Cs) of 3254 C/g at 1 A/g, energy density of 207 Wh/kg at 1 A/g and cyclic stability of 1000 cycles with a capacity retention rate of 97%. These outstanding electrochemical performances suggest that the prepared BiOBr/RGO nanocomposite may serve as a promising working electrode for supercapattery applications in the near future.

MoS2 Quantum Dot-Optimized Conductive Channels for a Conjugated Polymer-Based Synaptic Memristor.

Donor-acceptor-type conjugated polymers are widely used in memristors due to their unique push-pull electron structures and charge transfer mechanisms. However, the inherently inhomogeneous microstructure of polymer films and their low crystallinity produce randomness that destabilizes formed conductive channels, giving polymer-based memristors unstable switching behavior. In this contribution, we prepared a synaptic device based on PM6-MoS2 QD (molybdenum disulfide quantum dot) nanocomposites. In the composites, MoS2 QDs provided the active centers for forming conductive channels via electron trapping and detrapping. They also controlled the directional formation of conductive channels between PM6 and MoS2 QDs, reducing randomness and giving devices a narrow switching voltage range and cycling longevity. The device exhibited continuous multistage conductance states under a direct current voltage sweep and simulated a variety of synaptic functions, including long-term potentiation, long-term depression, short-term potentiation, short-term depression, paired-pulse facilitation, spiking-rate-dependent plasticity, and "learning experience" behavior. The memristor could also perform arithmetic, including "counting" and "subtraction" operations. This work provides a new approach to improving the performance of memristors for neuromorphic computing.

Charge Transport in Conjugated and Saturated Hydrocarbons: Comparing Ballistic and Cotunneling Contributions.

The comparison between electrical transport in CnH2n+2S2 alkane and CnHn+2S2 alkene (n = 4, 6, 8, 10) is studied by using a generalized Breit-Wigner approach and considering coherent transport mechanisms and eventual changes in the state of charge (i.e., cotunneling processes) for both molecules. In general, the conductance of alkanes tends to be smaller than that of similar-sized alkenes. However, cotunneling processes have an important participation in the overall transport in the case of alkanes but not for the alkene family. The progressive changes in both the eigenenergies of the relevant frontier molecular orbitals of the charged species and their spatial localization play decisive roles in the observed differences. While the molecular orbitals of the charged species of the conjugated molecules are hardly affected by the applied voltage, their saturated counterparts are quite sensitive to the external field. With this, successive avoided-crossing events between the molecular orbitals of the single-charged alkane molecules can lead to the appearance of nonballistic conduction channels that make no negligible contributions to the molecular transport.

Proximity induced band gap opening in topological-magnetic heterostructure (Ni80Fe20/p-TlBiSe2/p-Si) under ambient condition

The broken time reversal symmetry states may result in the opening of a band gap in TlBiSe2 leading to several interesting phenomena which are potentially relevant for spintronic applications. In this work, the quantum interference and magnetic proximity effects have been studied in Ni80Fe20/p-TlBiSe2/p-Si (Magnetic/TI) heterostructure using physical vapor deposition technique. Raman analysis shows the symmetry breaking with the appearance of A21u mode. The electrical characteristics are investigated under dark and illumination conditions in the absence as well as in the presence of a magnetic field. The outcomes of the examined device reveal excellent photo response in both forward and reverse bias regions. Interestingly, under a magnetic field, the device shows a reduction in electrical conductivity at ambient conditions due to the crossover of weak localization and separation of weak antilocalization, which are experimentally confirmed by magnetoresistance measurement. Further, the photo response has also been assessed by the transient absorption spectroscopy through analysis of charge transfer and carrier relaxation mechanisms. Our results can be beneficial for quantum computation and further study of topological insulator/ferromagnet heterostructure and topological material based spintronic devices due to high spin orbit coupling along with dissipationless conduction channels at the surface states.

Numerical Investigation on Thermal Performance in Low-Enthalpy Geothermal System Under the Impact of Anisotropic Reservoir Heterogeneity and Well Layout

Abstract The utilization of low-enthalpy geothermal systems holds substantial potential for mitigating the greenhouse effect. However, the thermal efficiency of geothermal systems is significantly influenced by the spatial distribution of reservoir property, particularly permeability and porosity. In this work, we systematically investigate the impact of anisotropic heterogeneity in porosity and permeability on geothermal performance using numerical method. The thermal performance is evaluated based on parameters such as thermal production lifetime, thermal breakthrough time, and thermal production energy. Our findings indicate that with an increase in correlation length from 100 to 500 m, highly heterogeneous reservoirs tend to regionalize pores, forming highly conductive fluid flow channels. This led to shorter thermal production lifetime and thermal breakthrough time. Moreover, the thermal performance varied significantly with different rotation angles in a double well layout, displaying a maximum difference of 41.17% compared to a homogeneous reservoir. This difference decreased with the number of wells, reaching 32.82% and 16.66% in triple and quadruple well layouts, respectively. Consequently, the thermal performance was more stable under uncertain well positions in the quadruple well layout, but with reduced heat extraction efficiency. Our research results provide valuable insights into the impact of anisotropic heterogeneity on thermal performance in low-enthalpy geothermal systems.

WOx channel engineering of Cu-ion-driven synaptic transistor array for low-power neuromorphic computing

The multilevel current states of synaptic devices in artificial neural networks enable next-generation computing to perform cognitive functions in an energy-efficient manner. Moreover, considering large-scale synaptic arrays, multiple states programmed in a low-current regime may be required to achieve low energy consumption, as demonstrated by simple numerical calculations. Thus, we propose a three-terminal Cu-ion-actuated CuOx/HfOx/WO3 synaptic transistor array that exhibits analogously modulated channel current states in the range of tens of nanoamperes, enabled by WO3 channel engineering. The introduction of an amorphous stoichiometric WO3 channel formed by reactive sputtering with O gas significantly lowered the channel current but left it almost unchanged with respect to consecutive gate voltage pulses. An additional annealing process at 450 °C crystallized the WO3, allowing analog switching in the range of tens of nanoamperes. The incorporation of N gas during annealing induced a highly conductive channel, making the channel current modulation negligible as a function of the gate pulse. Using this optimized gate stack, Poole–Frenkel conduction was identified as a major transport characteristic in a temperature-dependent study. In addition, we found that the channel current modulation is a function of the gate current response, which is related to the degree of progressive movement of the Cu ions. Finally, the synaptic characteristics were updated using fully parallel programming and demonstrated in a 7 × 7 array. Using the CuOx/HfOx/WO3 synaptic transistors as weight elements in multilayer neural networks, we achieved a 90% recognition accuracy on the Fashion-MNIST dataset.

Mo70Cu30 composites synthesized by infiltration sintering and hot rolling with simultaneously improved mechanical and electrical properties

In this study, Cu@Mo composite powders, prepared using an electroless plating method, were applied to synthesize Mo70Cu30 composites using infiltration sintering and hot rolling technologies. Microstructure, mechanical properties and physical properties of the synthesized Mo70Cu30 composites were studied. Results showed that the prepared Cu@Mo composite powders have a core-shell structure with Mo particles uniformly coated with Cu layers. Density values of Mo70Cu30 composites before and after the hot rolling process are 98.45% and 99.79%, their tensile strengths are 517 MPa and 753 MPa, and their thermal conductivities are 179.7 W/(m·K) and 214.6 W/(m·K), respectively. Formation of network Cu channels in the Mo70Cu30 composite is beneficial for achieving uniform microstructures, increased density, and enhanced thermal conductivity. Rolling process deforms the Cu phase into a fibrous shape, forming a good thermal conductivity channel and refining the Mo phase grains. The enhancement in the mechanical properties of the composites is attributed to the combined mechanisms of deformation strengthening and fine grain strengthening.

Synergistic Integration of Amorphous Cobalt Phosphide with a Conductive Channel for Highly Efficient Electrocatalytic Nitrate Reduction to Ammonia.

Electrocatalytic nitrate reduction to ammonia (NO3RR) is regarded as a viable alternative reaction to "Haber Bosch" process. Nevertheless, it remains a major challenge to explore economical and efficient electrocatalysts that deliver high NH3 yield rates and Faraday efficiencies (FE). Here, it demonstrates the fabrication of a 3D core-shell structured Co-carbon nanofibers (CNF)/ZIF-CoP for NO3RR application. Benefitting from the distinct electron transport property of Co-CNF and desirable mass transfer ability from amorphous CoP framework, the as-prepared Co-CNF/ZIF-CoP exhibits large NH3 FE (96.8 ± 3.4% at -0.1V vs reversible hydrogen electrode (RHE)) and high yield rate (38.44 ± 0.65mg cm-2 h-1 at -0.6V vs RHE), which are better than Co-CNF/ZIF-crystal CoP. Density functional theory (DFT) calculations further reveal that amorphous CoP presents a lower energy barrier in the rate determination step of the protonation of *NO to produce *NOH intermediates compared with crystal CoP, resulting in a superior NO3RR performance. Eventually, an aqueous galvanic Zn-NO3 - battery is assembled by using Co-CNF/ZIF-CoP as cathode material to achieve efficient production of NH3 whilst simultaneously supplying electrical power. This work offers a reliable strategy to construct amorphous metal phosphide framework on conducting CNF as efficient electrocatalyst and enriches its promising application for NO3RR.