Excellent Electrical Conductivity Research Articles

Structural Modulation of Nanographenes Enabled by Defects, Size and Doping for Oxygen Reduction Reaction

Nanographenes are among the fastest‐growing materials used for the oxygen reduction reaction (ORR) thanks to their low cost, environmental friendliness, excellent electrical conductivity, and scalable synthesis. The perspective of replacing precious metal‐based electrocatalysts with functionalized graphene is highly desirable for reducing costs in energy conversion and storage systems. Generally, the enhanced ORR activity of the nanographenes is typically deemed to originate from the heteroatom doping effect, size effect, defects effect, and/or their synergistic effect. All these factors can efficiently modify the charge distribution on the sp2‐conjugated carbon framework, bringing about optimized intermediate adsorption and accelerated electron transfer steps during ORR. In this review, the fundamental chemical and physical properties of nanographenes are first discussed about ORR applications. Afterward, the role of doping, size, defects, and their combined influence in boosting nanographenes’ ORR performance is introduced. Finally, significant challenges and essential perspectives of nanographenes as advanced ORR electrocatalysts are highlighted.

Functionalized Triangular Carbon Quantum Dot Stabilized Gold Nanoparticles Decorated Boron Nitride Nanosheets Interfaced for Electrochemical Detection of Cardiac Troponin T.

The fast, and highly sensitive estimation of cardiac troponin T (cTnT) is crucial for the early identification of acute myocardial infarction (AMI). The electrochemical immunoassay-based (EIB) sensors are highly promising for this purpose, as they offer precise measurements and can be directly assessed in intricate matrices, including blood. To increase sensitivity, EIB sensors use nanomaterials or amplification processes, which can be laborious to develop. With this, we develop an electrochemical immunosensor for the sensitive detection of cardiac troponin T (cTnT). The sensing platform is composed of functionalized triangular carbon quantum dots stabilized gold nanoparticles which are integrated with boron nitride nanosheets (caf-TCQDs@AuNPs on HO-BNNS). Ferrocene carboxylic acid (Fc-COOH) serves as the signal label. The composite was developed and examined using several techniques such as X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM), cyclic voltammetry, and chronocoulometry. The caf-TCQDs@AuNPs supported on HO-BNNS, have a large surface area and excellent electrical conductivity, and serve as an effective platform for the immobilization of anti-cTnT monoclonal antibodies via carbodiimide coupling. The Fc-COOH, functioning as a signal label through the oxidation process, was integrated with caf-TCQDs@AuNPs on the HO-BNNS platform to establish an electrochemical immunosensor for the detection of cTnT. The electrochemical immunosensor demonstrated excellent performance for the determination of cTnT under optimal conditions, exhibiting a linearity range spanning from 0.0001 to 100 ng mL-1, accompanied by a low detection limit of 0.0013 ng mL-1. Notably, the immunosensor revealed high specificity, as well as excellent levels of reproducibility and reliability for the examination of human serum samples.

Structural Modulation of Nanographenes Enabled by Defects, Size and Doping for Oxygen Reduction Reaction.

Nanographenes are among the fastest-growing materials used for the oxygen reduction reaction (ORR) thanks to their low cost, environmental friendliness, excellent electrical conductivity, and scalable synthesis. The perspective of replacing precious metal-based electrocatalysts with functionalized graphene is highly desirable for reducing costs in energy conversion and storage systems. Generally, the enhanced ORR activity of the nanographenes is typically deemed to originate from the heteroatom doping effect, size effect, defects effect, and/or their synergistic effect. All these factors can efficiently modify the charge distribution on the sp2-conjugated carbon framework, bringing about optimized intermediate adsorption and accelerated electron transfer steps during ORR. In this review, the fundamental chemical and physical properties of nanographenes are first discussed about ORR applications. Afterward, the role of doping, size, defects, and their combined influence in boosting nanographenes' ORR performance is introduced. Finally, significant challenges and essential perspectives of nanographenes as advanced ORR electrocatalysts are highlighted.

Rational design of MoS2/CNT heterostructure with rich S-vacancy for enhanced HER performance.

Molybdenum disulfide (MoS2) is a promising electrocatalyst for the hydrogen evolution reaction (HER) due to excellent stability and low cost. However, the utilization in electrocatalytic hydrogen evolution is constrained by inherent shortcomings, including fewer edge active sites, poor dispersion, and electrical conductivity. In this work, MoS2 was compounded with carbon nanotubes (CNTs), which are known for their high specific surface area and excellent electrical conductivity. These CNTs, laden with oxygen-containing functional groups, provided nucleation sites that facilitated the rapid assembly of MoS2 nanoflowers under hydrothermal conditions within 3h. Due to their diminutive size (∼300nm), these nanoflowers possess a large specific surface area and numerous active sites at their edges. Furthermore, MoS2 nanoflowers exhibited a high concentration of intrinsic S-vacancies. This heterojunction material exhibited superior HER properties. In addition, density functional theory simulation further confirmed that the MoS2 with S vacancy and CNT heterojunction electrocatalysts (VS-M/C) provided a fast charge transfer pathway for water electrolysis, and analysis showed that the conduction band minimum and valence band maximum were mainly contributed by the d orbits of Mo and the p orbits of C. This study proffered a novel approach for the engineering of high-performance MoS2-based HER electrocatalysts.

Electron Transport and Ion Diffusion in Hydrogen-Bonded Interlayer Cross-Linked Graphene/MXene for Wearable Micro-Sensors.

2D graphene and MXene have attracted much attention in the field of energy storage devices and wearable sensors due to their excellent electrical conductivity and mechanical properties. However, the capacitance of their composites is limited by low electron transport and sluggish ion diffusion due to the lack of electron transport and ion diffusion channels between stacked interlayers. Herein, this work reports the possibility of using disodium terephthalate as an auxiliary conductive bridge to cross-link the interlayer interaction between graphene and MXene from theoretical analysis and experimental verification. The cross-linker with a dicarboxyl group and a conjugated structure forms hydrogen bonds with the hydroxyl groups on the surface of graphene and MXene to provide a pathway for interlayer electron transfer, while inhibiting interlayer stacking and ensuring an effective ion diffusion process. To verify the actual effect of this approach, micro-sensors are assembled by the integration of micro-supercapacitors. The assembled micro-sensors demonstrate real-time monitoring of body movements and temperature signals. This work provides a feasible strategy to promote electron transport and ion diffusion in layered composites to design next-generation multifunctional micro-devices.

Porous Single-Crystal Nitrides for Enhanced Pseudocapacitance and Stability in Energy Storage Applications.

Supercapacitors have emerged as a prominent area of research in energy storage technology, primarily because of their high power density and notable stability compared to batteries. However, their practical implementation is hindered by their low energy densities and insufficient long-term stability. In this study, bulk porous Nb4N5 and Ta3N5 single crystals with excellent pseudocapacitance and electrical conductivity are successfully prepared by solid-phase transformation method. These monolithic porous single crystals (PSC) exhibit a long-range ordered crystalline architecture and substantial specific surface area, which facilitate rapid charge transport and ion diffusion within the electrolyte-permeated crystal lattice. Notably, the areal capacitance of the porous Nb4N5 single crystals is 12.9 F cm-2 at a current density of 6mA cm-2 and 35.08 F cm-2 at a scan rate of 1mV s-1. Furthermore, the energy density reached 1.79 mWh cm-2 at a power density of 20mW cm-2, demonstrating their high energy storage capability. Moreover, these porous Nb4N5 single crystals exhibited robust capacitance retention and exceptional cycling stability, making them promising candidates for use as electrodes in energy storage applications. These results underscore the significant potential of porous metal nitride single crystals in advancing the field of capacitive energy storage.

A Supramolecular Gel that Exhibits Multi‐Stimuli Responsiveness and High Conductivity through Host‐Guest Interactions

AbstractA network‐structured supramolecular gel is constructed through host‐guest interactions between conjugated ligands and metal ions, leading to enhanced mechanical properties and excellent electrical conductivity. This overcomes the problem of insufficient conductance due to the presence of solvent in the interstitial region of the supramolecular gel. Supramolecular gels can undergo reversible sol‐gel transitions by controlling the pH or temperature of the system. In addition, a method has been developed to determine the specific binding ratio of host‐guest molecules by conductivity tests, and has been used to verify the specific binding ratio of crown ether to potassium ions. To explain the high conductivity of supramolecular metallic gels, DFT and SEM have been employed to elucidate their conductivity mechanism.

Soft Artificial Muscle of Poly(vinyl chloride) Gel with an Imperceptible Liquid Metal Electrode.

Electrodes with high electrical conductivity, yet good flexibility and mechanical compliance, are critical for electroactive artificial muscles. Herein, a promising liquid metal (LM) electrode is proposed by transforming eutectic gallium-indium (EGaIn) LM with high surface tension into paste-like LM with solid Ga2O3 shells. The developed compliant LM electrode not only shows high conductivity and negligible additional stiffness but also displays excellent electrical stability during cyclic actuation. Based on the LM electrode, the poly(vinyl chloride) gel (PVCG) artificial muscle developed exhibits the maximum actuation strain of 18.7% at a low electric field strength of 9 V μm-1 and maintains excellent durability without obvious performance attenuation after 10,000 s. A comparison shows that the as-developed PVCG artificial muscle is superior over that based on widely used carbon electrodes. Moreover, an artificial upper limb and crawling worm were manufactured to explore the great potential of PVCG artificial muscle in the robotic field. In addition, the practical application demonstration of the PVCG artificial muscle in the biomimetics field is also successfully fulfilled through the design of reasonable structures. Due to its easy fabrication, excellent electrical conductivity, and high mechanical compliance, the newly developed LM electrode is promising for high-performance PVCG artificial muscles in bionic robots.

Electrochemical Performance of MoB/Si3N4 Heterojunction as a Potential Anode Material for Li Ion Batteries.

In response to the current policy of high storage capacity, two-dimensional (2D) materials have revealed promising prospects as high-performance electrode materials. MoB, as a type of such material, is widely regarded as an anode candidate for Li-ion batteries due to its large specific surface area and abundant ion diffusion channels; the long-term cycling stability, however, is poor owing to material pulverization during the cycle. Therefore, MoB/Si3N4 heterojunction in this work is proposed as an anode material, with Si3N4 acting as a skeleton, maintaining the stability of the structure, while retaining the high energy storage properties of MoB as well. In addition, a certain built-in electric field is formed between them, which can play a role in regulating charge transfer, improving the ion transport channel, and accelerating the migration rate. Herein, the structural, electronic, and electrochemical properties are systematically investigated by first-principles calculations; the final results indicate that the heterojunction anode material does indeed have built-in electric fields, which promote the anode material to possess excellent electrical conductivity and outstanding electrochemical property. Meanwhile, the introduction of vacancy defects can bolster the diffusion kinetic performance of ion transport and greatly reduce the diffusion energy barrier of Li ions, which is conducive to the realization of rapid charge and discharge for the Li ion battery. Based on the synergistic effect of two single-component materials, the synthesized anode material displays a high theoretical capacity of 461 mAh/g, and the calculated open-circuit voltage is 0.66 V, within the range of the negative electrode criterion of 0-1 V, which can effectively play a role in preventing the formation of Li dendrites; these properties are comparable to other 2D anode materials as well. Given these intriguing properties, the MoB/Si3N4 heterojunction is an exceptional candidate for advanced LIB high-performance anode materials.

1T′-MoSP monolayer as an anode material for sodium-ion batteries with ultrahigh storage capacity and ultralow diffusion barrier

Sodium-ion batteries (SIBs) have gained significant attention due to the abundant availability and low cost of sodium. However, the search for high-performance anode materials remains a critical challenge in advancing SIB technology. Based on first-principles swarm-intelligence structure calculations, we propose a metallic 1T′-MoSP monolayer as an anode material that offers a remarkably high storage capacity of 1011 mA h g−1, an ultralow barrier energy of 0.04 eV, and an optimal open-circuit voltage of 0.29 V, ensuring high rate performance and safety. Additionally, the monolayer presents favorable wettability with commonly used SIB electrolytes. Even after adsorbing three-layer Na atoms, the 1T′-MoSP monolayer retains its metallic nature, ensuring excellent electrical conductivity during the battery cycle. These desirable properties make the 1T′-MoSP monolayer a promising anode material for SIBs.

Two-Dimensional ABS4 (A and B = Zr, Hf, and Ti) as Promising Anode for Li and Na-Ion Batteries.

Metal ion intercalation into van der Waals gaps of layered materials is vital for large-scale electrochemical energy storage. Transition-metal sulfides, ABS4 (where A and B represent Zr, Hf, and Ti as monolayers as anodes), are examined as lithium and sodium ion storage. Our study reveals that these monolayers offer exceptional performance for ion storage. The low diffusion barriers enable efficient lithium bonding and rapid separation while all ABS4 phases remain semiconducting before lithiation and transition to metallic states, ensuring excellent electrical conductivity. Notably, the monolayers demonstrate impressive ion capacities: 1639, 1202, and 1119 mAh/g for Li-ions, and 1093, 801, and 671 mAh/g for Na-ions in ZrTiS4, HfTiS4, and HfZrS4, respectively. Average voltages are 1.16 V, 0.9 V, and 0.94 V for Li-ions and 1.17 V, 1.02 V, and 0.94 V for Na-ions across these materials. Additionally, low migration energy barriers of 0.231 eV, 0.233 eV, and 0.238 eV for Li and 0.135 eV, 0.136 eV, and 0.147 eV for Na make ABS4 monolayers highly attractive for battery applications. These findings underscore the potential of monolayer ABS4 as a superior electrode material, combining high adsorption energy, low diffusion barriers, low voltage, high specific capacity, and outstanding electrical conductivity.

Glycerol Vapor Assisted Cu Direct Bonding: Implications for 3D Semiconductor Packaging

AbstractAs the scaling down of semiconductor devices reaches its physical limits, 3D stacking packaging technology is emerging as a new miniaturization solution. Among the various 3D packaging technologies, Cu direct bonding is widely adopted due to copper's excellent electrical conductivity and the absence of intermetallic compounds for solder bumps. Since copper readily undergoes oxidation, technologies that prevent Cu surface oxidation during Cu direct bonding are essential. However, current research suggests that the methods require additional pretreatment processes, which demand high costs. In this study, a Cu direct bonding method utilizing glycerol vapor is developed to effectively streamline the pretreatment steps. The potential of glycerol as a reducing agent and antioxidant for Cu is demonstrated using a silicon die sample with a size of 10 × 10 mm2, verified through the X‐ray photoelectron spectroscopy. The Cu direct bonding for 3D semiconductor packaging is successfully performed under glycerol vapor atmosphere, without any plasma pretreatment. The cross‐section of the bonded specimens is examined by scanning electron microscopy, and mechanical reliability is assessed by die shear testing.

Ginkgo biloba-derived biogenic carbon quantum dots modified NiCo-LDH: significantly enhanced energy density and cycle stability

A significant development in the usage of hydroxides in energy storage applications is the creation of LDH materials with excellent electrical conductivity and structural stability. Due to their poor electrical conductivity, bimetallic layered double hydroxides have weak rate performance and limited cycling ability. To address these issues, carbon quantum dots derived from waste Ginkgo biloba and labeled as GBC were incorporated in the preparation of NiCo-LDH. With the many oxygen-containing functional groups on the surface, GBC increases the composite's wettability while maintaining the LDH lamellar structure. It can also create localized electron-rich regions, which give the material more space and channels for electron transport, improving electrical conductivity and rate performance. Furthermore, GBC is evenly dispersed throughout the LDH skeleton, giving the composites a homogenous surface state that can mitigate the structural collapse issue brought on by the volume change during cycling. The findings demonstrate that by modulating the amount of GBC, NiCo-LDH/GBC-20 performs better electrochemically than NiCo-LDH. The capacity was 276.1 mAh g-1 at 1 A g-1, an 84.1% improvement over NiCo-LDH. Finally, the energy density displayed by the NiCo-LDH/GBC-20//AC HSC device is 72.5 Wh kg-1 (at 798.7 W kg-1), and maintains 78.2% of its original capacity after 12,000 cycles.

Facile fabrication of FeSe/MnSe composite for improved electrochemical characterization by hydrothermal route

Globally, researchers are primarily focused on creating new electrode materials with high energy and power density (Pd) to develop the efficiency of energy storage devices. This work demonstrates significant advancements in use of transition metal selenide as electrode material for supercapacitors (SCs). FeSe/MnSe composite was produced by a hydrothermal approach and the findings indicated a notable improvement in electrochemical characteristics due to the combined effect of FeSe and MnSe materials. The exceptional electrochemical performance of FeSe/MnSe composite electrode attributed to its inherent features, including crystal structure, excellent electrical conductivity with varying oxidation states, distinct morphology and large surface area. Moreover, FeSe/MnSe composite demonstrated specific capacitances (Csp) of 1533.23 F/g at current density of 1.0 A g−1 with notable energy density (68.70 Wh kg−1) and Pd (284 W kg−1). Furthermore, the FeSe/MnSe composite electrode demonstrates remarkable cyclability, sustaining its effectiveness reliably for more than 5000 cycles while also exhibiting low-impedance features with a Rct of 0.09 Ω. This study delves into a new approach for creating unique FeSe/MnSe electrodes that show potential as a reliable option with extended cycling durability and increased energy capacity for use in energy storage devices.

A biomacromolecular additive based on pullulan polysaccharide to enhance the life of lead-acid battery packs in DC systems

Abstract With the rapid growth in demand for mobile power, lead-acid batteries still occupy a large market share due to their excellence in energy storage. However, their lifespan is affected by various factors, which limits the application efficiency and environmental friendliness. In this regard, this paper proposes a method to enhance the service life of lead-acid battery packs by applying biomacromolecule additives. A lead-acid battery pack modification method is investigated by introducing chitosan, a natural macromolecule with excellent electrical conductivity and biodegradation properties, into lead-acid batteries. So that the chitosan-modified material forms a stable and protective film on the surface of the battery electrode plate, thereby reducing the analysis of sulphate crystals on the electrode surface. The method of modification of lead-acid battery packs has been studied. Comparative analysis of the experimental data shows that the modified battery pack exhibits lower charge transfer impedance and better electrochemical stability than the traditional lead-acid battery during the cyclic charge/discharge test. Through the cycle charge/discharge test, the energy loss of the battery with biomolecules is 30% lower than that of the unmodified battery, and the number of charge/discharge cycles increases by 60%, which effectively prolongs the service life of the lead-acid battery. The progress of this paper not only has guiding significance for the performance improvement of traditional lead-acid batteries but also provides a significant theoretical and experimental basis for the development and application of environmental friendly battery materials.

Spatially controllable fluid hydrogel with in-situ electrospinning PCL/chitosan fiber for treating irregular wounds

Skin injuries sustained during exercise are often irregular in shape and frequently accompanied by infections. Bacteria residing in the crevices of these wounds can lead to persistent infections. Routine wound monitoring, which requires removing the wound dressing to assess recovery, is inconvenient and increases the risk of infection. To address this, we prepared a polyvinyl alcohol/polyhydroxylated fullerenes ((PVA/PHF) hydrogel with good fluidity and photothermal antibacterial properties, which can penetrate into the crevices of irregular wounds. After the hydrogel was applied to the wound, the hydrogel was locally defined by the polycaprolactone/Chitosan (PCL/CS) membrane of in-situ electrospinning, which effectively killed bacteria, and the healing efficiency was increased by 240 % in the wound healing experiment. The PVA/PHF hydrogel exhibits excellent electrical conductivity, making it suitable for real-time monitoring of human body motion as a strain sensor. This capability provides doctors with an accurate basis for wound assessment. At the same time, the hydrogel can achieve self-healing within 1.5 s and withstand up to 2200 % tensile strain, which can be used for large-scale motion monitoring of the human body. This flowable hydrogel, capable of penetrating wound crevices, offers a dual function of both treatment and monitoring.

Chiral Nematic Graphene Films with a mesoporous Structure.

Ordering a crucial material like pure-graphene into the chiral nematic structure can potentially revolutionize the fields of photonics, chiral separation, and energy storage. However, the controlled fabrication of highly ordered graphene films with a long-range chiral nematic mesoporous structure is very challenging and as such, has not been achieved. Here, a chiral-template-directed chemical vapor deposition growth strategy is presented for the precise fabrication of mesoporous chiral nematic graphene films by using nanocrystalline cellulose as templates. It is evidenced that such graphene films possess the left-hand helical ordering, chiral nematic mesoporous structure with adjustable pore sizes (6.4-13.1nm), tailored pitch, excellent electrical conductivity (556 S cm-1), high specific surface area (1508 m2g-1) and mechanical flexibility. By coating Na anode with this film, uniform Na plating is achieved with no dendrite formation, resulting from its unique chiral nematic structure and tunable physicochemical properties. The films also achieved impressive thickness-dependent electromagnetic shielding, i.e., 35-63dB, demonstrating their potentially multi-disciplinary applications.

In Situ Construction of Polypyrrole–Silver Composite Conductive Phase in High‐Performance Polyimide Sponge and Study of Sensing Behavior Under Microstress

Composites comprising conductive polymers and metal particles have garnered considerable interest in sensor technology due to their excellent electrical conductivity. However, producing controllable pressure sensors that retain high sensitivity under microstress remains challenging. Polyimide (PI) sponge exhibits excellent chemical and thermal stability and a porous structure that facilitates considerable deformation under low stress levels and results in good sensitivity to external forces. Herein, a conductive polymer–metal composite conductive phase, polypyrrole–silver (PPy–Ag), is directly fabricated on the PI surface through incipient network conformal growth. This method ensures that the PPy–Ag composite maintains optimal performance within its original temperature range, thereby enhancing detection sensitivity at low stress levels. The maximum conductivity of the fabricated PPy–Ag/PI composite sponge‐based flexible piezoresistive sensor is 2.42 × 10−4 S m−1, and the sensitivity is recorded at 16.31 kPa−1 within a stress range of 0–80 Pa. After undergoing 1000 compression cycles, the sensor exhibits commendable stability and reproducibility.

Graphene: future prospects for biomedical engineering applications

Graphene is one of the allotropic forms of Carbon. It is typically presented as a thin, almost transparent, and very lightweight sheet, despite its remarkable mechanical strength. Recent studies have demonstrated that graphene has significant potential for application in the medical industry, not only due to its mechanical resistance and lightness, which suggest its use in prosthetics and bionic limbs, but also because of its excellent electrical conductivity, indicating its potential in medical measurement equipment. Moreover, graphene's biocompatibility and resistance to corrosion make it an ideal material for long-term medical implants. It has been explored in the development of biosensors, enabling real-time monitoring of biological signals such as heart rate and brain activity. For instance, graphene-based sensors could be implanted to detect subtle electrical changes in neurons, which might be particularly useful in neuroprosthetics or for individuals with spinal cord injuries. Graphene's flexibility also paves the way for the creation of flexible electronic devices that could be worn on the skin or integrated into clothing for continuous health monitoring. These innovations could revolutionize personalized medicine by offering more accurate, accessible, and non-invasive diagnostic tools. As research continues to advance, graphene holds the promise of transforming biomedical engineering with cutting-edge applications that could improve patient care and treatment outcomes.

PTAA‐infiltrated thin‐walled carbon nanotube electrode with hidden encapsulation for perovskite solar cells

AbstractIn perovskite solar cells (PSCs), expensive gold or silver metal has traditionally been utilized as the rear electrode for highly efficient performance. In this context, carbon nanotube (CNT) electrodes have been considered promising rear electrodes because of their excellent electrical conductivity, mechanical strength, and chemical stability in PSCs. Despite these favorable characteristics, concerns have been raised about the power conversion efficiency (PCE) and stability of PSCs based on CNTs due to the porosity of CNT electrodes. In this study, we employed both poly(triarylamine) (PTAA) infiltration and rear electrode hidden encapsulation approaches to address issues related to the porosity of thin‐walled carbon nanotube (TWCNT) electrodes to achieve high efficiency and stability. The infiltration of low‐molecular‐weight PTAA into the TWCNT electrode reduced electrode porosity while simultaneously improving the interfacial contact of the TWCNT layer with the perovskite layer. Furthermore, a novel encapsulation design was employed to prevent air and water exposure of the TWCNT electrode, which significantly enhanced device stability. PSCs with TWCNT rear electrodes developed on the basis of these strategies have the best PCE of 19.5% and show long‐term stability, retaining 96% and 74% of the initial PCE after 225 h at maximum power point tracking under AM 1.5G illumination and 916 h at 85°C/85% relative humidity, respectively.image