Metallic Conductivity Research Articles

Bimetallic Sulfides Cr0.99V1.8S4 with Loosely Packed Structure: Exploring the Boundary of Conversion and Intercalation Sodium-Ion Storage Mechanism.

Metal sulfide electrodes for sodium-ion batteries face trade-offs among high capacity, fast kinetics, and stability. The challenge lies in breaking and restoring metal-sulfur bonds and allowing rapid ionic transport. Here we explore the boundary of conversion- and intercalation-type metal sulfides to develop ideal sodium-ion storage materials. We focus on sulfides of vanadium and chromium because of their adjacent atomic numbers but different energy storage mechanism. Among various sulfides of vanadium and chromium, a loosely packed bimetallic sulfide, Cr0.99V1.8S4, with cationic vacancies and metallic conductivity (4.28 S m-1), shows optimal sodium-ion storage performance: an initial Coulombic efficiency of 95.6%, a reversible capacity of 551 mAh g-1 at 1.6 C, and maintaining 100% capacity after 600 cycles at a high rate of 16-66 C.

Metalgel Fiber with Excellent Electrical and Mechanical Properties.

With the rapid advancement of soft electronics, particularly the rise of fiber electronics and smart textiles, there is an urgent need to develop high-performance fiber materials with both excellent electrical and mechanical properties. However, existing fiber materials including metal fibers, carbon-based fibers, intrinsically conductive polymer fibers, and composite fibers struggle to simultaneously meet the requirements. Here, we introduce a metalgel fiber with a unique structure. In metalgel fibers, liquid metal forms a continuum, extending throughout the entire volume of nanostructured fucoidan polymer networks, which are immobilized by electrostatic interactions. The distinctive structure imparts the fiber with metallic conductivity (2.8 × 106 S·m-1), softness (Young's modulus of 1.8 MPa), and stable electromechanical coupling properties (resistance change <5% after 20,000 times pressing, stretching, bending, and twisting cycles). The metalgel fibers were woven into multifunctional smart textiles, highlighting their potential for practical applications.

A Versatile Dual-Responsive Shape-Memory Gripper via Additive Manufacturing Toward High-Performance Cross-Scale Objects Maneuvering.

Smart grippers serving as soft robotics have garnered extensive attentions owing to their great potentials in medical, biomedical, and industrial fields. Though a diversity of grippers that account for manipulating the small objects (e.g., tiny micrometer-scale droplets) or the big ones (e.g., centimeter-scale screw) has been proposed, however, cross-scale maneuvering of these two species leveraging an all-in-one intelligent gripper is still challenging. Here, a magnet/light dual-responsive shape-memory gripper (DR-SMG) is reported, based on the hybrid of Fe-nanoparticles and shape-memory polymers. Thanks to its photothermal effect, the closed-state DR-SMG switches to the open state under the synergetic cooperation of near-infrared-ray (NIR) and a circinate magnetic field, referring to the temporary state. On the other hand, once the NIR is loaded, the temporary opened DR-SMG would reconfigure to its permanent closed state owing to shape-memory effect. Leveraging this principle, DR-SMG can grasp and release diverse cross-scale objects ranging from micrometers to centimeters including metals, glass balls, polymers, and small liquids. Significantly, this versatile DR-SMG is capable of spatially delivering multifunctional chemical droplets and conductive liquid metals, thereby enabling lab-on-chip and electrical switch applications. This work provides new insights into intelligent grippers and further advances the field of soft robotics.

Hydrogen Sensing via Heterolytic H2 Activation at Room Temperature by Atomic Layer Deposited Ceria.

Ultrathin atomic layer deposited ceria films (< 20 nm) are capable of H2 heterolytic activation at room temperature, undergoing a significant reduction regardless of the absolute pressure, as measured under in-situ conditions by near ambient pressure X-ray photoelectron spectroscopy. ALD-ceria can gradually reduce as a function of H2 concentration under H2/O2 environments, especially for diluted mixtures below 10%. At room temperature, this reduction is limited to the surface region, where the hydroxylation of the ceria surface induces a charge transfer towards the ceria matrix, reducing Ce4+ cations to Ce3+. Thus, ALD-ceria replicates the expected sensing mechanism of metal oxides at low temperatures without using any noble metal decorating the oxide surface to enhance H2 dissociation. The intrinsic defects of the ALD deposit seem to play a crucial role since the post-annealing process capable of healing these defects leads to decreased film reactivity. The sensing behavior was successfully demonstrated in sensor test structures by resistance changes towards low concentrations of H2 at low operating temperatures without using noble metals. These promising results call for combining ALD-ceria with more conductive metal oxides, taking advantage of the charge transfer at the interface and thus modifying the depletion layer formed at the heterojunction.

Zinc Grid Based Transparent Electrodes for Organic Photovoltaics

AbstractZinc is the fifth most electrically conductive metal and is available at a fraction of the cost of the most widely used transparent electrode materials; silver, indium‐tin oxide, and poly(3,4‐ethylenedioxythiophene) polystyrene sulfonate, but has been surprisingly overlooked as a current carrying element in organic photovoltaics. Here, a transparent flexible electrode based on an embedded zinc grid with ≈1 µm linewidth is reported and its utility as a drop‐in replacement for indium‐tin oxide coated glass electrodes in model organic photovoltaic devices is demonstrated. The zinc grids are fabricated using the unconventional approach of condensation coefficient modulation, using a micro‐contact printed patterned layer of poly(perfluorooctylmethylmethacrylate) to resist zinc condensation in the gaps between grid lines, together with a copper acetylacetonate seed layer to nucleate zinc condensation where grid lines are required. Density functional theory calculations of the strength of the interaction between zinc atoms and this fluorinated polymer provide fundamental insight into why the latter is so effective at resisting zinc condensation. The resulting zinc grid is embedded in a flexible polymer support and transferred to a flexible plastic substrate by delamination, which enables recovery and reuse of the fluorinated polymer.

Molecule-Based Proton-Electron Mixed Conductor with the Highest Ambipolar Conductivity.

Proton-electron mixed conductors (PEMCs) are an essential component for potential applications in hydrogen separation and energy conversion devices. However, the exploration of PEMCs with excellent mixed conduction, which is quantified by the ambipolar conductivity, σamb = σeσH/(σe + σH) (σe: electronic conductivity; σH: proton conductivity), is still a great challenge, largely due to the lack of structural characterization of both conducting mechanisms. In this study, we prepared a molecule-based proton-electron mixed-conducting cation radical salt, (ET)4[Pt2(pop)2(Hpop)2]·PhCN (ET: bis(ethylenedithio)tetrathiafulvalene, pop2-: P2H2O52-), by electrocrystallization. The salt shows metallic electronic conduction, which arises from the (ET)2•+ layers, with a high σe value (1-2 S cm-1 at room temperature). The metallic state was corroborated by magnetic susceptibility measurement and band structure calculation. The salt also shows superprotonic conduction (σH = 2.1 × 10-2 S cm-1 at room temperature under dried conditions), which relies on the one-dimensional (1D) hydrogen-bonding network of protonated paddlewheel-type Pt-dimer complex anions, [Pt2(pop)2(Hpop)2]2-. Crystallographic and computational studies revealed the presence of infinite intra- and intermolecular O-H···O hydrogen bonds, which show a double-well-like potential energy curve with a negligible energy barrier in the 1D chain, facilitating Grotthuss-type proton hopping via Lewis basic sites. Among the structurally defined PEMCs, the present salt displays the highest room temperature σamb value of 2.1 × 10-2 S cm-1 even under dried conditions. The σamb value has the same order as those of reported perovskites-type metal oxides at high temperatures and achieves a level that is beneficial for the practical applications.

Origin of oxygen partial pressure-dependent conductivity in SrTiO3

SrTiO3 (STO) displays a broad spectrum of physical properties, including superconductivity, ferroelectricity, and photoconductivity, making it a standout semiconductor material. Despite extensive research, the oxygen partial pressure-dependent conductivity in STO has remained elusive. This study leverages first-principles calculations and systematically investigates the intrinsic defect properties of STO. The results reveal that VO, VSr, and TiSr are the dominant intrinsic defects, influencing STO's conductivity under varying O chemical potentials (oxygen partial pressures). Under O-poor condition, VO is the predominant donor, while VSr is the main acceptor. As the oxygen pressure increases, TiSr emerges as a critical donor defect under O-rich conditions, significantly affecting the conductivity. Additionally, the study elucidates the abnormal phenomenon where VTi, typically an acceptor, exhibits donor-like behavior due to the formation of O-trimer. This work offers a comprehensive understanding of how intrinsic defects tune the Fermi level, thereby altering STO's conductivity from metallic to n-type and eventually to p-type across different O chemical potentials. These insights resolve the long-standing issue of oxygen partial pressure-dependent conductivity and explain the observed metallic conductivity in oxygen-deficient STO.

Flexible Electronic Patch Utilizing Gelatin Film for Heart and Brain Signal Detection.

Flexible electronic patches have been widely studied in various fields. However, they still face serious challenges in cardio-brain signaling monitoring to achieve accurate adhesion and detection with compatibility in mildly humid environments. To tackle these challenges, we engineered a gelatin hydrogel film cross-linked with a biocompatible matrix factor and combined it with a blend of liquid metal and PVP to create the flexible electronic patch. The flexible patch has good biocompatibility and fatigue resistance due to the incorporation of liquid metal and natural gelatin, with the conductivity of liquid metal and minimal toxicity of the gelatin film. It is possible to securely insert it into the body for a duration of 3 weeks while maintaining monitoring functionality and withstanding 10 000 cycles of flexural fatigue. This research provides an innovative approach to the future advancement of flexible electronic patches.

Explore the physical properties of the synthesized UiO-66, Zn-BiOBr, and Zn-BiOBr/UiO-66 heterostructures for optical applications

The Zn-BiOBr/UiO-66 Heterostructures were prepared using a simple wet chemical method. Three heterostructures were prepared by varying the weight percentage of UiO-66 to Zn-BiOBr. The prepared materials' chemical compositions and phase structure were investigated using Fourier transform infrared (FTIR), X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS). Furthermore, the morphology was investigated via Field-emission scanning electron microscope (FE-SEM), energy dispersive X-ray (EDX), and elemental mapping techniques. The optical features were analyzed through UV–vis spectrophotometry. The bandgap energy was calculated using the Tauc equation and was found 4.24eV for UiO66 and 2.17eV for the ZnBiOBr composite. After combining the ZnBiOBr composite with the UiO66 material the bandgap energy of the composite decreased to 4.07, 3.94, and 3.75eV after doping 10, 20, and 30% UiO-66, respectively. Additionally, the refractive index of the Zn-BiOBr/UiO-66 heterostructure increases from 2.1520 for the UiO-66 composite to about 2.1929, 2.2254, and 2.2748 for 10, 20, and 30% UiO66. Moreover, an enhancement was observed for other optical parameters like electronegativity, metallization, and optical conductivity. Besides, the W-DD model was used to investigate the nonlinear optical parameters, which showed an improvement in the first- and third-order nonlinear optical susceptibility, and nonlinear refractive index values with increasing UiO-66 content in the composite matrix.

BA-ATEMNet: Bayesian Learning and Multi-Head Self-Attention for Theoretical Denoising of Airborne Transient Electromagnetic Signals.

Airborne transient electromagnetic (ATEM) surveys provide a fast, flexible approach for identifying conductive metal deposits across a variety of intricate terrains. Nonetheless, the secondary electromagnetic response signals captured by ATEM systems frequently suffer from numerous noise interferences, which impede effective data processing and interpretation. Traditional denoising methods often fall short in addressing these complex noise backgrounds, leading to less-than-optimal signal extraction. To tackle this issue, a deep learning-based denoising network, called BA-ATEMNet, is introduced, using Bayesian learning alongside a multi-head self-attention mechanism to effectively denoise ATEM signals. The incorporation of a multi-head self-attention mechanism significantly enhances the feature extraction capabilities of the convolutional neural network, allowing for improved differentiation between signal and noise. Moreover, the combination of Bayesian learning with a weighted integration of prior knowledge and SNR enhances the model's performance across varying noise levels, thereby increasing its adaptability to complex noise environments. Our experimental findings indicate that BA-ATEMNet surpasses other denoising models in both single and multiple noise conditions, achieving an average signal-to-noise ratio of 37.21 dB in multiple noise scenarios. This notable enhancement in SNR, compared to the next best model, which achieves an average SNR of 36.10 dB, holds substantial implications for ATEM-based mineral exploration and geological surveys.

Magnetointeractive Cr2Te3-Coated Liquid Metal Droplets for Flexible Memory Arrays and Wearable Sensors.

Magnetic liquid metal droplets, featured by unique fluidity, metallic conductivity, and magnetic reactivity, are of growing significance for next-generation flexible electronics. Conventional fabrication routes, which typically incorporate magnetic nanoparticles into liquid metals, otherwise encounter the pitfall pertaining to surface adhesivity and corrosivity over device modules. Here, an innovative approach of synergizing liquid metals with 2D magnetic materials is presented, accordingly creating chromium(III)-telluride-coated liquid metal (CT-LM) droplets via a simple self-assembly process. The CT-LM droplets exhibit controllable deformation and locomotion under magnetic fields, demonstrate nonadherence to various surfaces, and enable cost-effective recycling of components. The functionality of CT-LM droplets is validated through their use in magnetointeractive memory devices to enable sensing/storing 64 magnetic paths and in wearable sensors as the flexible vibrator for dynamic gesture recognition with machine learning assistance. This work opens new avenues for the functional droplet design and broadens the horizons of flexible electronics.

Bimetallic Conductive Metal Organic Framework Nanorods with Atomically Dispersed Fe and Co Sites for Efficient Oxygen Evolution

Bimetallic Conductive Metal Organic Framework Nanorods with Atomically Dispersed Fe and Co Sites for Efficient Oxygen Evolution

2D Vertically Conductive Metal─Organic Framework Electrolytes: Will They Outperform 3D MOFs for Solid State Batteries?

Lithium-ion batteries are currently the mainstream for almost all portables, and quickly expand in electrical vehicles and grid storage applications. However, they are challenged by the poor safety regarding organic liquid electrolytes and relatively low energy density. Solid-state batteries, characterized by using solid-state electrolytes (SSEs), are recognized as the next-generation energy technology, owing to their intrinsically high safety and potentially superior energy density. However, developing SSEs is impeded by several key factors, including low ionic conductivity, interfacial issues, and high-cost in industrial scales. Recently, a novel category of SSEs, known as frameworked electrolytes (FEs), has emerged as a formidable contender for the transition to all-solid-state batteries. FEs exhibit a unique macroscopically solid-state nature and microscopically sub-nanochannels offering high ionic conductivity. In this perspective, the unique lithium-ion transport mechanisms within FEs are explored and 2D vertically conductive metal-organic framework (MOF) is proposed as an even more promising FE candidate. The abundant active sites in the 1D sub-nanochannels of 2D vertically conductive MOFs facilitate efficient ion transport, favorable interfacial compatibility, and scalable industrial applications. This perspective aims to boost the emergence of novel SSEs, promoting the realization of long-expected all-solid-state batteries and inspiring future energy storage solutions.

Long‐Cycle Stable Zn2+ Storage in 2D Conductive Metal–Organic Frameworks via Exclusive Ligand Redox Mechanism

Abstract2D conductive metal–organic frameworks (2D c‐MOFs) have emerged as novel cathode materials in the development of rechargeable aqueous zinc‐ion batteries (ZIBs) because of its integrated multiple redox‐active moieties. However, the redox of the metal nodes usually leads to the collapse of the c‐MOF structure during Zn2+ insertion/extraction process, thereby curtailing its cycling lifespan. Herein, a triphenylene‐catecholate‐based 2D c‐MOF (Zn‐HHTP) is fabricated by chelating the inactive Zn nodes, endowing the structural stability during charge and discharge processes only through ligand redox. The 1D open channel of Zn‐HHTP facilitates rapid insertion and extraction of zinc ions, thus enabling stable working of ZIBs at high rates. Impressively, Zn‐HHTP as cathode in ZIBs exhibits an ultra‐long cycling stability with capacity retention of 86.6% after 4000 cycles at the current density of 4 A g−1, exceeding the other MOF‐based cathodes ever reported. Density functional theory (DFT) calculations combined with ex situ X‐ray photo‐electron spectroscopy (XPS) further elucidate the redox mechanism between catechol and benzene ring of HHTP during the successive insertion/extraction of Zn2+, due to their comparatively negative electrostatic potentials. This work provides a new strategy to prolong the cycling capability of ZIBs by utilizing the highly active non‐metallic redox moieties in 2D c‐MOFs.

A Review of Transparent Conducting Films (TCFs): Prospective ITO and AZO Deposition Methods and Applications.

This study offers a comprehensive summary of the current states as well as potential future directions of transparent conducting oxides (TCOs), particularly tin-doped indium oxide (ITO), the most readily accessible TCO on the market. Solar cells, flat panel displays (FPDs), liquid crystal displays (LCDs), antireflection (AR) coatings for airbus windows, photovoltaic and optoelectronic devices, transparent p-n junction diodes, etc. are a few of the best uses for this material. Other conductive metals that show a lot of promise as substitutes for traditional conductive materials include copper, zinc oxide, aluminum, silver, gold, and tin. These metals are also utilized in AR coatings. The optimal deposition techniques for creating ITO films under the current conditions have been determined to be DC (direct current) and RF (radio frequency) MS (magnetron sputtering) deposition, both with and without the introduction of Ar gas. When producing most types of AR coatings, it is necessary to obtain thicknesses of at least 100 nm and minimum resistivities on the order of 10-4 Ω cm. For AR coatings, issues related to less-conductive materials than ITO have been considered.

A Transparent and Robust Ionogel with Stress-Induced Microphase Separation Property and Crack Insensitivity for Visual Force Sensor.

Gel with ionic conductivity and stretchability is considered as an ideal alternative to conventional rigid metallic conductors in the flexible electronics. However, present gels suffer from poor mechanical properties and crack sensitivity due to their weak intermolecular (chain) interactions and homogeneous network structure. Herein, a transparent and tough polyacrylamide (PAM) ionogel is designed, which can form stress-induced microphase-separated domains with high hydrogen bonding density under stress to inhibit crack propagation. Benefiting from multiple hydrogen bonding interactions, the PAM ionogel exhibited maximum tensile stress of 5.19 ±0.52MPa, maximum tensile strain of 685.49 ±22.15%, and fracture toughness of 10.11 ±1.63kJm-2. On the other hand, the visual force sensor is realized by utilizing the stress-induced changes in the grayscale and electrical resistance of the PAM ionogel, which allowed real-time and visual monitoring of the stress applied to an object as a whole or in part. This work may open new avenues for the development of stable and reliable flexible sensors.

Charge transport mechanism in [GeOx](z)[SiO2](1-z) based MIS structures

The mechanisms of conductivity in metal–insulator–semiconductor (MIS) structures based on [GeOx](z)[SiO2](1-z) films (0.25 ≤ z ≤ 1) fabricated by co-evaporation of germanium oxide and silicon oxide powders in vacuum and deposition on a p+-type silicon substrate are studied. Indium tin oxide deposited by magnetron method is used as the top electrode. According to IR spectroscopy, Ge–O, Si–O, and Ge–O–Si bonds are detected in the films, while no features related to the presence of germanium clusters are found in the Raman spectra. The current–voltage characteristics (I–V curves) are measured at different temperatures and analyzed by applying the eight most common models of charge transport in MIS structures. It is found that the experimental I–V curves are most accurately approximated in the space charge limited current model, and the parameters of the charge traps are determined within this model.

Shot Noise in a Metal Close to the Mott Transition.

SrIrO3 is a metallic complex oxide with unusual electronic and magnetic properties believed to originate from electron correlations due to its proximity to the Mott metal-insulator transition. However, the nature of its electronic state and the mechanism of metallic conduction remain poorly understood. We demonstrate that the shot noise produced by nanoscale SrIrO3 junctions is strongly suppressed, inconsistent with diffusive quasiparticle transport. Analysis of thermal effects and scaling with the junction length reveals that conduction is mediated by collective hopping of electrons almost localized by correlations. Our results provide insight into the non-Fermi liquid state close to the Mott transition and advance shot noise measurements as a powerful technique for the study of quantum materials.

Spectral SPR effect in thin films of high-conductive metals and features of SPR-biosensors implementation in chromatic mode

In this paper, we have evaluated the application of various types of highly conductive metals for implementing the effect of spectral surface plasmon resonance (SPR) within a visible spectrum range to achieve more efficient and productive registration of biomolecules in a liquid medium using tricolor RGB cameras. Thin films of gold, silver, copper, and aluminum, as well as a bimetallic coating of silver with a gold superlayer on a glass substrate, are considered. Detailed calculations of the spectral characteristics of reflection at SPR excitation in the Kretschmann geometry are performed, particularly when a thin dielectric film is formed on the metal surface that imitates a layer of biomolecules. For each of the specified metals, the width of the region of implementation of the full-fledged SPR effect in the visible range of the spectrum is determined, and the sensitivity of the optical response to the influence of an external dielectric layer is assessed.

Conductive Metal–Organic Frameworks for Rechargeable LiOH-Based Li–O2 Batteries

Conductive Metal–Organic Frameworks for Rechargeable LiOH-Based Li–O₂ Batteries