Conductivity Of Graphene Research Articles

Research on the Optimal Protection Parameters of Graphene Composite Conductive Coatings Combined with Impressed Current Cathodic Protection Technology in Marine Atmospheric Environments

Based on the principle of a micropore-filling electrolyte, a graphene composite conductive coating combined with impressed current cathodic protection (ICCP) technology was constructed and applied in a marine atmospheric environment. To further explore the optimal protection parameters of the graphene composite conductive coating combined with ICCP technology in a marine atmospheric environment, the effects of the coating damage area (A), impressed voltage (B), and distance from the contact point (C) on the protective performance of the coating were investigated via orthogonal experiments. The optimal protection voltage and effective protection distance were verified by super-depth-of-field morphology observations and electrochemical tests. The orthogonal experimental results show that the primary and secondary orders affecting the protective performance of the conductive graphene composite coating are as follows: applied voltage (B) > coating damage area (A) > distance from the point of contact (C). The optimal protective parameters of the coating in the marine atmospheric environment are an applied voltage of 0.7 V, a damage rate of ≤1%, and a distance from the point of contact of 190 mm. The experimental results show that the corrosion potential of the sample is the highest under an applied voltage of 0.7 V, and the corrosion products do not diffuse to the surface of the coating. When the polarization resistance (Rp) values at 110 mm and 190 mm from the negative electrode at the point of contact are greater, the corrosion rate is lower, and the coating protection performance is better.

Broadband low-loss polarization-insensitive graphene-integrated photonic crystal fiber modulators in the near-infrared range

The amplitude modulator with the function of converting electric signal to optical amplitude modulation is a key component in high-speed optical communication links. In this paper, we demonstrate a variety of two-dimensional graphene-integrated photonic crystal fiber modulators for efficient near-infrared amplitude modulation with ultra-low insertion loss. Taking the advantages of the perfect total internal reflection of the porous photonic crystal fiber and flexible tunability of the graphene conductivity, the modulation depth of 0.075 dB μm−1 with a low optical loss of 2.13 × 10−4 dB μm−1, a long propagation length of ∼20 mm and polarization-insensitive characteristics in a wide wavelength of 1.3 to 1.8 μm can be achieved. This high-performance modulator may have great potential applications in various high-speed telecommunication, interconnection, and graphene-based integrated photonic systems.

Analysis of semiconductor properties of fabricated graphene materials

Introducing dopant elements into graphene is a crucial process for creating bandgaps, which will have significant importance in developing nanoelectronic devices in the future. In this study, we provide an analysis of the electrical and carrier mobility properties of graphene doped with BN in ratios of 1 %, 3 %, and 5 %, graphene 95 %, ZnO-3 %, and BN2 %, graphene-95 %, Al2O3-3 % and BN-2 %, graphene-95 %, TiO2-3 % and BN-2 % by using a sintering process. Upon analyzing the band structure, it was determined that the mentioned materials demonstrate a bandgap in graphene. The resistivity values for fabricated graphene materials doped with different nanoparticles are estimated using the Source-meter Unit (SMU) at room temperature (25°C), 100°C and 200°C. The conductivity of graphene is 8.93E+07 Ω−1cm−1 and reduced gradually with the doping percentages. The resistivity of graphene is measured at 1.12 E-08 Ω.cmand increases with the doping percentages, and carrier mobility is measured to be 9239 cm2V−1s−1 and gradually reduced with the doping percentages. The temperature-dependent conductivity is determined using electrical conductivity under the constant relaxation time approximation.

Interfacial enhancement enables highly conductive reduced graphene oxide-based yarns for efficient electromagnetic interference shielding and thermal regulation

Although the coating of conductive graphene onto commercial yarns is promising for scalable production, the resulting conductive yarns are susceptible to the coating detachment, causing reduced conductivity and poor stability. Herein, we propose a scalable and cost-effective interfacial enhancement strategy for fabricating highly conductive yarns with satisfactory mechanical properties by modifying polyamide yarns with polyethyleneimine to enhance their interaction with graphene oxide (GO) sheets and subsequently reducing the GO component with hydroiodic acid. Because the enhanced interfacial interactions of the polyethyleneimine-modified polyamide yarns with the GO sheets improve the loading of GO and the coating stability, the resultant yarns can withstand bending, embroidering, sewing and weaving, maintaining an extraordinary conductivity of 4.7 × 103 S m−1 after 10000-cycle bending. The conductive textiles woven by the yarns reach an excellent electromagnetic interference (EMI) shielding effectiveness of 66.7 dB at the thickness of 0.615 mm along with superior hydrophobicity, satisfactory air permeability, and high electrothermal and solar-thermal energy conversion performances. The EMI shielding effectiveness of the textile is well maintained even after 5000-cycle bending, demonstrating its satisfactory stability. This work demonstrates an interfacial enhancement strategy for the large-scale fabrication of multifunctional yarns that hold great promise for EMI shielding, personal thermal regulation, and deicing applications.

One‐Step Laser Synthesis of Copper Nanoparticles and Laser‐Induced Graphene in a Paper Substrate for Non‐Enzymatic Glucose Sensing

AbstractThe synergy resulting from the high conductivity of graphene and catalytic properties of metal nanoparticle has been a resource to improve the activity and functionality of electrochemical sensors. This work focuses on the simultaneous synthesis of copper nanoparticles (CuNPs) and laser‐induced graphene (LIG) derived from paper, through a one‐step laser processing approach. A chromatography paper substrate with drop‐casted copper sulfate is used for the fabrication of this hybrid material, characterized in terms of its morphological, chemical, and conductive properties. Appealing conductive properties are achieved, with sheet resistance of 170 Ω sq−1 being reached, while chemical characterization confirms the simultaneous synthesis of the conductive carbon electrode material and metallic copper nanostructures. Using optimized laser synthesis and patterning conditions, LIG/CuNPs‐based working electrodes are fabricated within a three‐electrode planar cell, and their electrochemical performance is assessed against pristine LIG electrodes, demonstrating good electron transfer kinetics appropriate for electrochemical sensing. The sensor's ability to detect glucose through a non‐enzymatic route is optimized, to assure good sensing performance in standard samples and in artificial sweat complex matrix.

Inkjet‐Printed 2D Heterostructures for Smart Textile Micro‐Supercapacitors

AbstractWearable electronic textiles (e‐textiles) have emerged as promising healthcare solutions, offering point‐of‐care diagnostics while maintaining breathability, comfort, durability, and environmental stability with strong mechanical performance. However, the lack of thin and flexible power supplies hinders their practical adoption. In this regard, textile‐based micro‐energy storage devices present an appealing solution. Inkjet printing offers the capability to produce high‐quality prints with sharp details and versatile substrate compatibility, making it an ideal choice for a wide array of printing applications. Here, the preparation of a range of inkjet‐printable 2D material inks is reported for the fabrication of ultra‐flexible and machine‐washable textile micro‐supercapacitors. Then 2D material heterostructures are proposed to enhance the performance of textile supercapacitors. This study reveals that a unique combination of highly conductive graphene with an insulator hexagonal boron nitride (h‐BN) can enhance the areal capacitance of graphene‐based textile supercapacitors by ≈82.48%. The heterostructure‐based supercapacitors also demonstrate higher energy (≈18.06 µWh cm−2) and power densities (≈4333.33 µW cm−2) with excellent capacitance retention (≈95% after 1000 cycles). These findings on inkjet‐printed heterostructure‐based supercapacitors may herald a new era for the future application of high‐performance micro‐supercapacitors within textile‐based wearable technology.

Emulsion-Based Multiscale Structural Design Realizes Lightweight and Superelastic Graphene Aerogels for Electromagnetic Interference Shielding.

Ultralight graphene aerogels with high electrical conductivity and superelasticity are demanded yet difficult to produce. A versatile emulsion-based approach is demonstrate to optimize multiscale structure of lightweight, elastic, and conductive graphene aerogels. By constructing Pickering emulsion using graphene oxide (GO), poly (amic acid) (PAA), and octadeyl amine (ODA), micron-level close-pore structure is realized while thermal shrinkage mismatch between GO and PAA creates numerous nanowrinkles during thermal annealing. GO nanosheets are bridged by PAA-derived carbon, enhancing the structural integrity at molecular level. These multiscale structural features facilitate rapid electron transport and efficient load transfer, conferring graphene aerogels with intriguing mechanical and electromagnetic interference (EMI) shielding properties. The emulsion-based graphene aerogel with an ultralow density of ≈3.0mg cm-3 integrates outstanding electrical conductivity, air-caliber thermal insulation, high EMI shielding effectiveness of 75.0dB, and 90% strain compressibility with superb fatigue resistance. Intriguingly, thanks to the gel-like rheological behavior of the emulsion, ultralight graphene scaffolds with programmable geometries are obtained by 3D printing. This work provides a general approach for the preparation of ultralight and superelastic graphene aerogels with excellent EMI shielding properties, showing broad application prospects in various fields.

Patterned Laser-Induced graphene enabling a High-Performance gas sensing Split-Ring resonator

The outstanding potential of microwave resonator-based energy-efficient gas sensors has been overshadowed by their underperforming gas sensing capabilities, especially insignificant sensitivity to detect low-concentration volatile organic compounds (VOCs). This unmet challenge persists primarily due to predominant metallic resonator structures, which further limit their wearable applications and pose environmental concerns. This work presents a laser-induced graphene (LIG)-enabled split-ring resonator (SRR) sensor on a flexible polyimide substrate for the rapid and sensitive detection of gaseous VOCs. To implement the sensor, the conductive traces of the SRR were created using a computer-controlled CO2 laser at an optimized power level, thus inducing 48 µm thick, conductive (24 S/cm) graphene layers on a polyimide substrate. The SRR gas sensor, in which LIG with three-dimensional networks of porosity serves as conductive and even gas-sensitive traces, benefits from a significantly enhanced interaction between the SRR’s electromagnetic field and VOC gases. As a proof of concept, a prototype of the LIG-enabled SRR was implemented and mounted on a test fixture. The developed gas sensor operated at a resonant frequency of 1.402 GHz, which exhibited rapid (∼17 s) and noticeable shifts when exposed to 200 ppm of different VOCs (acetone, ethanol, methanol, toluene, and isopropyl alcohol). Additionally, the sensor demonstrated a linear correlation between the resonant frequency and acetone gas concentration (1 ppm-200 ppm), with a sensitivity of 188 KHz/ppm. These electromagnetic and gas sensing results suggest that polyimide-derived LIG traces can replace metal microstrip lines in the SRR structure, opening up possibilities for high-performance microwave resonator gas sensors, even suitable for flexible and wearable applications.

High-Performance Sensing Platform Based on Morphology/Lattice Collaborative Control of Femtosecond-Laser-Induced MXene-Composited Graphene.

Flexible sensors based on laser-induced graphene (LIG) are widely used in wearable personal devices, with the morphology and lattice arrangement of LIG the key factors affecting their performance in various applications. In this study, femtosecond-laser-induced MXene-composited graphene (LIMG) is used to improve the electrical conductivity of graphene by incorporating MXene, a 2D material with a high concentration of free electrons, into the LIG structure. By combining pump-probe detection, laser-induced breakdown spectroscopy (LIBS), and density functional theory (DFT) calculations, the morphogenesis and lattice structuring principles of LIMG is explored, with the results indicating that MXene materials are successfully embedded in the graphene lattice, altering both their morphology and electrical properties. The structural sparsity and electrical conductivity of LIMG composites (up to 3187 Sm-1) are significantly enhanced compared to those of LIG. Based on these findings, LIMG has been used in wearable electronics. LIMG electrodes are used to detect uric acid, with a minimum detection limit of 2.48µM. Additionally, LIMG-based pressure and bending sensors have been successfully used to monitor human limb movement and pulse. The direct in situ femtosecond laser patterning synthesis of LIMG has significant implications for developing flexible wearable electronic sensors.

Ultrafast reaction kinetic of polyaniline in flexible hydrogel electrodes facilitated by graphene ribbons

Abstract By loading energy storage active materials on hydrogel which is inherently flexible, the flexibility of electrode materials can be simply realized, thereby achieving the flexibility of energy storage devices. However, the polymer network that constructs the three-dimensional skeleton of the hydrogel is not conductive, which inhibits the redox ability of the active material. If a high speed conductive structure can be added to the colloidal phase, the performance of the flexible electrode material can be greatly improved. Here, we introduce redox graphene ribbons into the polyvinyl alcohol hydrogel loaded with polyaniline. The in situ three-dimensional conductive graphene network greatly enhanced the conductivity of the hydrogel electrode, thus increasing the specific capacitance to as high as 1117 F g−1 at 2 mg cm−2 mass loading, with a retention ratio of 66.96% from 0.5 A g−1 to 20 A g−1. These highlighted properties enable the PRP hydrogel as an electrode for flexible supercapacitors, which provides a promising possibility for the practical application of wearable electronics.

Synergistic effects of 1T–2H MoS2 and laser-reduced graphene Oxide–ZnO scaffold composite catalyst for efficient hydrogen evolution reaction

A composite catalyst, zinc-doped laser-reduced graphene oxide (LrGO), is synthesized with highly dispersed molybdenum disulfide (MoS2) nanolayers using laser exfoliation followed by a hydrothermal process. The resultant LrGO–ZnO/1T–2H MoS2 (GZM3) catalyst exhibits enhanced hydrogen evolution reaction (HER) catalytic performance and improved stability. It achieves small overpotentials of 94 and 191.5 mV at a current density of 10 mA cm−2, under acidic and alkaline conditions, respectively. This superior catalytic activity is attributed to the high electrical conductivity and large electrochemical surface area of graphene, along with efficient charge transfer facilitated by Zn ions between LrGO–ZnO and 1T–2H MoS2.

Highly conductive, stretchable, and biocompatible graphene oxide biocomposite hydrogel for advanced tissue engineering

The importance of hydrogels in tissue engineering cannot be overemphasized due to their resemblance to the native extracellular matrix. However, natural hydrogels with satisfactory biocompatibility exhibit poor mechanical behavior, which hampers their application in stress-bearing soft tissue engineering. Here, we describe the fabrication of a double methacrylated gelatin bioink covalently linked to graphene oxide (GO) via a zero-length crosslinker, digitally light-processed (DLP) printable into 3D complex structures with high fidelity. The resultant natural hydrogel (GelGOMA) exhibits a conductivity of 15.0 S m-1as a result of the delocalization of theπ-orbital from the covalently linked GO. Furthermore, the hydrogel shows a compressive strength of 1.6 MPa, and a 2.0 mm thick GelGOMA can withstand a 1.0 kg ms-1momentum. The printability and mechanical strengths of GelGOMAs were demonstrated by printing a fish heart with a functional fluid pumping mechanism and tricuspid valves. Its biocompatibility, electroconductivity, and physiological relevance enhanced the proliferation and differentiation of myoblasts and neuroblasts and the contraction of human-induced pluripotent stem cell-derived cardiomyocytes. GelGOMA demonstrates the potential for the tissue engineering of functional hearts and wearable electronic devices.

Green-Solvent-Based Conductive Graphene Ink Prepared via Liquid-Phase Exfoliation of Graphite with Water-Soluble 2,6-Azulene-Based Copolymers as Stabilizers

Green-Solvent-Based Conductive Graphene Ink Prepared via Liquid-Phase Exfoliation of Graphite with Water-Soluble 2,6-Azulene-Based Copolymers as Stabilizers

Reactivation of dissolved polysulfides with nitrogen doped graphene decorated carbon cloth as an effective interlayer for magnesium-sulfur battery

The theoretically high energy densities and wide availability of active materials have led to great interest in the development of magnesium‑sulfur (MgS) batteries. However, poor electronic conductivity of sulfur, active material dissolution, polysulfide shuttling, and poor cycling stability are major challenges that need to be tackled. Herein we observed the pristine MgS cell faces significant overcharging issues and cell failure is common within 30 cycles with significant capacity decay. With the help of XRD and elemental mapping realized that the dissolved liquid polysulfides are metastable in nature. Due to the high sulfophilic nature of the separator, polysulfide absorption leads to slow crystal growth inside the separator. This active material trapping might be the reason for quick capacity decay. We attempted to revive the dissolved polysulfides by introducing conductive nitrogen-doped graphene (N-gpn)@Carbon cloth(CC) interlayer between the electrodes and separator. This interlayer has a high polysulfide absorption nature, which allows the battery to demonstrate an initial capacity of 1075 mAh g−1 and increased cycling stability to 100 cycles. However, this stability was further enhanced to 300 cycles by protecting the anode. Theoretical considerations suggest that among all polysulfides, MgS8, has the strongest interaction with N-gpn and can be trapped most favorably in a defective N-gpn. This leads to enhanced utilization of the active material and improved cycling stability.

Improved-quality graphene films via the synergism of large nanosheet aligning and nanotube bridging for flexible supercapacitors

Scalable production of reduced graphene oxide (rGO) films with high mechanical-electrical properties is desirable as these films are candidates for wearable electronics devices and energy storage applications. Removing structural incompleteness such as wrinkles or voids in the graphene films, which are generated from the assembly process, would greatly optimize their mechanical properties. However, the densely stacked graphene sheets in the films degrade their ionic kinetics and thus limit their development. Here, a horizontal-longitudinal-structure modulating strategy is demonstrated to produce enhanced mechanical, conductive, and capacitive graphene films. Typically, two-dimensional large graphene sheets (LGS) induce regular stacking of graphene oxide (GO) during the assembly process to reduce wrinkles, while one-dimensional single-walled carbon nanotubes (SWCNT) bridge with graphene sheets to strengthen the multidirectional intercalation and reduce GO layer restacking. The simultaneous incorporation of LGS and SWCNT synergistically creates a fine microstructure by improving the alignment of graphene sheets, increasing continuous conductive pathways to facilitate electron transport, and enlarging interlayer spacing to promote electrolyte ion diffusion. As a result, the obtained graphene films are flat and exhibit signally reinforced mechanical properties, electrical conductivity (38727 S m-1), as well as specific capacitance (232 F g-1) as supercapacitor electrodes compared to those of original rGO films. Moreover, owing to the comprehensive improved properties, a flexible gel supercapacitor assembled by the graphene film-based electrodes shows high energy density, good flexibility, and excellent cycling stability (93.8% capacitance retention after 10 000 cycles). This work provides a general strategy to manufacture robust graphene structural materials for energy storage applications in flexible and wearable electronics.

Wrapping stem cells with wireless electrical nanopatches for traumatic brain injury therapy

Electrical stimulation holds promise for enhancing neuronal differentiation of neural stem cells to treat traumatic brain injury. However, once the stem cells leave the stimulating material and migrate post transplantation, electrical stimulation on them is diminished. Here, we wrap the stem cells with wireless electrical nanopatches, the conductive graphene nanosheets. Under electromagnetic induction, electrical stimulation can thus be applied in-situ to individual nanopatch-wrapped stem cells on demand, stimulating their neuronal differentiation through a MAPK/ERK signaling pathway. Consequently, 41% of the nanopatch-wrapped stem cells differentiate into functional neurons in 5 days, as opposed to only 16.3% of the unwrapped ones. The brain injury male mice implanted with the nanopatch-wrapped stem cells and exposed to a rotating magnetic field 30 min/day exhibit significant recovery of brain tissues, behaviors, and cognitions, within 28 days. This study opens up an avenue to individualized electrical stimulation of transplanted stem cells for treating neurodegenerative diseases.

Flexible composite films with ultrahigh through-plane thermal conductivity yet low graphene content

Graphene-based polymeric composites have become one of the promising thermal interface materials (TIMs) for the high integration electronic devices due to the excellent intrinsic thermal conductivity of graphene. However, the challenges still remain, such as ordered alignment of graphene in elastic polymer and regulation of phonon scattering at graphene/graphene interface. In this study, a vertically oriented graphene framework within a flexible silicone rubber matrix was fabricated by non-solvent induced phase separation (NIPs) coupled with an in in-situ welding technique. The as-prepared film exhibits an outstanding through-plane thermal conductivity of 29.5W/mK at low graphene loading of 7.5 wt%, which indicates an exceptionally high thermal conductivity enhancement per 1 wt% graphene content (specific TCE) over 1950 %/wt%. Furthermore, the composite films demonstrate excellent conformability inherited from the silicone rubber matrix and achieves low contact resistance of 40–70 Kmm2W−1 under various pressure and interfacial conditions. This study contributes to a deeper insight into the development of the high-performance graphene-based polymeric TIMs.

Nonreciprocal response of electrically biased graphene-coated fiber.

Here, we theoretically investigate the nonreciprocal response of an electrically biased graphene-coated dielectric fiber. By electrically biasing the graphene coating along the fiber axis, the dynamic conductivity of graphene exhibits a nonsymmetric response with respect to the longitudinal component of guided-mode wave vectors. Consequently, the guided waves propagating in two opposite directions may encounter distinct propagation features. In this work, the electromagnetic properties, such as modal dispersion and some field distributions, are presented, and the strength of nonreciprocity is discussed for different parameters of graphene, such as its chemical potential and material loss. Furthermore, the influence of the radius of the fiber on the nonreciprocal response is investigated. We envision that such nonreciprocal optical fibers may find various potential applications in the THz regime.

Reverse degree-based topological indices study of molecular structure in triangular ϒ-graphyne and triangular ϒ-graphyne chain

Topological indices are mathematical descriptors of the structure of a molecule that can be used to predict its properties. They are derived from the graph theory, which describes the topology of a molecule and its connectivity. The main objective is mathematical modeling and topological properties of ϒ-graphyne. Current research focuses on two structures made from hexagonal honeycomb graphite lattices named triangular ϒ-graphyne and triangular ϒ-graphyne chains. The authors have simultaneously computed the first and second Reverse Zagreb indices, reverse hyper-Zagreb indices, and their polynomials. This research also derives mathematical closed-form formulas for some of its fundamental degree-based molecular descriptors. Researchers have been trying to synthesize a novel carbon form called Graphyne. For over a decade but with no success. Recently, some researchers have made a breakthrough in generating Carbons elusive allotrope and solved a long-standing problem in carbon materials. This wonder material is created to rival the conductivity of graphene but with control. These results opened new ways of research in the fields of semiconductors, electronics and optics. Furthermore, graphical and tabular results will help to investigate the structure-property relationships in γ-graphyne.

A facile one-pot synthesis of ultrafine Sn/N-doped carbon/graphene oxide composite for superior lithium-ion storage

Metallic Sn is considered as a promising candidate of anode materials for lithium-ion batteries (LIBs) owing to its high capacity and ease of preparation. However, it undergoes severe mechanical damage after several lithiation/delithiation cycles due to the large volume change (∼300%). In this study, ultrafine Sn nanograins are embedded in N-doped amorphous carbon and then anchored onto reduced graphene oxide (rGO) via a facile one-pot synthesis route. The resulting composite consists of highly active Sn nanograins, three-dimensional carbon frameworks and highly conductive graphene oxide matrices. This unique configuration endows the composite with promising electrochemical performance. It delivers a reversible capacity of 1392 mAh g−1 at a current density of 50 mA g−1. When cycled after 300 times at 500 mA g−1, it still maintains a reversible capacity of 805 mAh g−1.