Scale Graphene Research Articles

Efficient Production of Graphene through a Partially Frozen Suspension Exfoliation Process: An Insight into the Enhanced Interaction Based on Solid-Solid Interfaces.

Liquid phase exfoliation (LPE) offers a promising path for scalable graphene production, but struggles with high energy consumption and low yield, with over 99.99% of the input energy wasted. Here, we present an energy-efficient approach for producing graphene via partially frozen-suspension exfoliation (PFE). As opposed to traditional liquid-solid interfaces, the solid-solid interface enhances shear strength between the frozen solvent and graphite from about 40 N m-2 to 105 N m-2. Additionally, the suspension flow transitions from turbulent to laminar, aligning graphite parallel to the flow direction and conducive to the effective utilization of shear force. Compared to conventional liquid-phase exfoliation (LPE), PFE improves energy efficiency by 102∼103 times. Furthermore, a production rate of 5 g h-1 has been achieved in a 10 L tank at an ultralow shear rate of 3 × 102 s-1.

Scalable and High-Quality Monolayer Graphene Transfer onto Polymer Membranes Assisted by Camphor

Scalable and High-Quality Monolayer Graphene Transfer onto Polymer Membranes Assisted by Camphor

Scalable Graphene Oxide Hollow Fiber Membranes for Dye Desalination Enabled by Multi-Purpose Polyamine Functionalization.

2D nanosheets such as graphene oxide (GO) can be stacked to construct membranes with fine-tuned nanochannels to achieve molecular sieving ability. These membranes are often thin to achieve high water permeance, but their fabrication with consistent nanostructures on a large scale presents an enormous challenge. Herein, GO-based hollow fiber membranes (HFMs) are developed for dye desalination by synergistically combining chemical etching to form in-plane nanopores (10-30nm) to increase water permeance and polyamine functionalization to improve underwater stability and enable facile large-scale production using existing membrane manufacturing processes. HFM modules with areas of 88 cm2 and GO layer thicknesses of ≈500nm are fabricated, and they exhibited a stable dye water permeance of 75 L m-2 h-1 bar-1, rejection of >99.5% for Direct red and Congo red, and Na2SO4/dye separation factor of 300-500, superior to state-of-the-art commercial membranes. The versatility of this approach is also demonstrated using different short polyamines and porous substrates. This study reveals a scalable way of designing 2D materials into high-performance robust membranes for practical applications.

Scalable graphene current collectors for enhanced thermal management in batteries

Scalable graphene current collectors for enhanced thermal management in batteries

Scalable Compliant Graphene Fiber-Based Thermal Interface Material with Metal-Level Thermal Conductivity via Dual-Field Synergistic Alignment Engineering.

High-performance thermal interface materials (TIMs) are highly desired for high-power electronic devices to accelerate heat dissipation. However, the inherent trade-off conflict between achieving high thermal conductivity and excellent compliance of filler-enhanced TIMs results in the unsatisfactory interfacial heat transfer efficiency of existing TIM solutions. Here, we report the graphene fiber (GF)-based elastic TIM with metal-level thermal conductivity via mechanical-electric dual-field synergistic alignment engineering. Compared with state-of-the-art carbon fiber (CF), GF features both superb high thermal conductivity of ∼1200 W m-1 K-1 and outstanding flexibility. Under dual-field synergistic alignment regulation, GFs are vertically aligned with excellent orientation (0.88) and high array density (33.5 mg cm-2), forming continuous thermally conductive pathways. Even at a low filler content of ∼17 wt %, GF-based TIM demonstrates extraordinarily high through-plane thermal conductivity of up to 82.4 W m-1 K-1, exceeding most CF-based TIMs and even comparable to commonly used soft indium foil. Benefiting from the low stiffness of GF, GF-based TIM shows a lower compressive modulus down to 0.57 MPa, an excellent resilience rate of 95% after compressive cycles, and diminished contact thermal resistance as low as 7.4 K mm2 W-1. Our results provide a superb paradigm for the directed assembly of thermally conductive and flexible GFs to achieve scalable and high-performance TIMs, overcoming the long-standing bottleneck of mechanical-thermal mismatch in TIM design.

Minimizing Contact Resistance and Flicker Noise in Micro Graphene Hall Sensors Using Persistent Carbene Modified Gold Electrodes.

Scalable micro graphene Hall sensors (μGHSs) hold tremendous potential for highly sensitive and label-free biomagnetic sensing in physiological solutions. To enhance the performance of these devices, it is crucial to optimize frequency-dependent flicker noise to reduce the limit of detection (LOD), but it remains a great challenge due to the large contact resistance at the graphene-metal contact. Here we present a surface modification strategy employing persistent carbene on gold electrodes to reduce the contact resistivity by a factor of 25, greatly diminishing μGHS flicker noise by a factor of 1000 to 3.13 × 10-14 V2/Hz while simultaneously lowering the magnetic LOD SB1/2 to 1440 nT/Hz1/2 at 1 kHz under a 100 μA bias current. To the best of our knowledge, this represents the lowest SB1/2 reported for scalable μGHSs fabricated through wafer-scale photolithography. The reduction in contact noise is attributed to the π-π stacking interaction between the graphene and the benzene rings of persistent carbene, as well as the decrease in the work function of gold as confirmed by Kelvin Probe Force Microscopy. By incorporating a microcoil into the μGHS, we have demonstrated the real-time detection of superparamagnetic nanoparticles (SNPs), achieving a remarkable LOD of ∼528 μg/L. This advancement holds great potential for the label-free detection of magnetic biomarkers, e.g., ferritin, for the early diagnosis of diseases associated with iron overload, such as hereditary hemochromatosis (HHC).

Scalable graphene foam with ultrahigh conductivity for stabilizing Pt towards efficient hydrogen evolution

Scalable graphene foam with ultrahigh conductivity for stabilizing Pt towards efficient hydrogen evolution

A scalable top-gate graphene field effect transistor with a polydimethylsiloxane dielectric

The limitations of modern CMOS technology have created a call to action for novel devices with great scalability potential. Graphene has been recognized as a suitable material for an enhanced transistor channel based on its incredibly large conductivity while also being easily scaled. Previous research has noted the importance of a top gate device structure, which is difficult to accomplish for graphene transistors due to graphene's incompatibility with oxide growth processes. A novel process flow for graphene field effect transistors with scalability is presented. The emphasis is on the growth of multilayer graphene using chemical vapor deposition and the implementation of polydimethylsiloxane as a gate dielectric. Polydimethylsiloxane gate insulator thickness of 815 nm and 570 nm were successfully developed on 4in large-scale wafers. Two devices of similar channel dimensions and different dielectric were compared and mobilities of 14.57cm2V−1s−1 and 0.44 cm2V−1s−1 were measured. Gate voltage sweeps from -20 V to 20 V also demonstrated channel current modulation with a charge neutrality point between 5 V and 8 V, indicating achievement of expected device operation.

Few-layer graphene production through graphite exfoliation in pressurized CO2 assisted by natural surfactant

Graphene research has captivated researchers worldwide, propelling innovation across diverse industries. Through the liquid-phase exfoliation methodology of graphite powder, we have demonstrated a rapid route for obtaining few-layer and multi-layer graphene using a natural surfactant, cardanol. Aqueous phase exfoliation of graphite in the presence of cardanol as a surfactant was conducted to obtain pre-exfoliated graphite suspensions. The influence of different ultrasonication times, 10, 20, and 30 min, and contact times with the surfactant, 1 and 60 min, on the stability and concentration of dispersed exfoliated graphite was evaluated. Results indicate that ultrasonication for 20 min resulted in improved stability and reduced graphene flake sizes, making it suitable for scalable graphene production. Subsequently, the most stable dispersions of exfoliated graphite were subjected to CO2-pressurized treatment. Promising results were obtained when employing cardanol at its critical micelle concentration. The graphene exhibited good structural quality, low defect density, and small stacking, with an average size of 15 nm, where 40 % of the stacked graphene was smaller than 5 nm. The findings provide valuable recommendations for the scalable production of graphene with multilayers and a few layers (FLG/MLG), using cardanol, a friendly surfactant, and a novel method of exfoliation utilizing supercritical CO2. This technology represents an innovative approach, with potential applications in supercapacitors, solar cells, biosensors, polymer composites, and advanced materials.

Influence of reactive environment on the growth of graphene by CVD method

Scalable graphene was grown on commercially purchased Cu foil by using the chemical vapor deposition method with a growth temperature and time of 900 °C and 30 min, respectively. The growth mechanism was investigated in a different reactive environment (gas flow). The crystallinity of the surface absorbed chemical species was identified through x-ray diffraction analysis. The structural morphology was determined by high-resolution transmission electron microscopy, scanning electron microscopy, and optical microscopy. Raman spectroscopy revealed the formation of defects in graphene under growth conditions. The growth environments of C2H4 and C2H2 result in higher defects than the CH4 state.

Establishing Pinhole Deposition Mode of Zn via Scalable Monolayer Graphene Film.

The uneven texture evolution of Zn during electrodeposition would adversely impact upon the lifespan of aqueous Zn metal batteries. To address this issue, tremendous endeavors are made to induce Zn(002) orientational deposition employing graphene and its derivatives. Nevertheless, the effect of prototype graphene film over Zn deposition behavior has garnered less attention. Here, it is attempted to solve such a puzzle via utilizing transferred high-quality graphene film with controllable layer numbers in a scalable manner on a Zn foil. The multilayer graphene fails to facilitate a Zn epitaxial deposition, whereas the monolayer film with slight breakages steers a unique pinhole deposition mode. In-depth electrochemical measurements and theoretical simulations discover that the transferred graphene film not only acts as an armor to inhibit side reactions but also serves as a buffer layer to homogenize initial Zn nucleation and decrease Zn migration barrier, accordingly enabling a smooth deposition layer with closely stacked polycrystalline domains. As a result, both assembled symmetric and full cells manage to deliver satisfactory electrochemical performances. This study proposes a concept of "pinhole deposition" to dictate Zn electrodeposition and broadens the horizons of graphene-modified Zn anodes.

High current treated-passivated graphene (CTPG) towards stable nanoelectronic and spintronic circuits.

Achieving enhanced and stable electrical quality of scalable graphene is crucial for practical graphene device applications. Accordingly, encapsulation has emerged as an approach for improving electrical transport in graphene. In this study, we demonstrate high-current treatment of graphene passivated by AlOx nanofilms as a new means to enhance the electrical quality of graphene for its scalable utilization. Our experiments and electrical measurements on large-scale chemical vapor-deposited (CVD) graphene devices reveal that high-current treatment causes persistent and irreversible de-trapping density in both bare graphene and graphene covered by AlOx. Strikingly, despite possible interfacial defects in graphene covered with AlOx, the high-current treatment enhances its carrier mobility by up to 200% in contrast to bare graphene samples, where mobility decreases. Spatially resolved Raman spectroscopy mapping confirms that surface passivation by AlOx, followed by the current treatment, reduces the number of sp3 defects in graphene. These results suggest that for current treated-passivated graphene (CTPG), the high-current treatment considerably reduces charged impurity and trapped charge densities, thereby reducing Coulomb scattering while mitigating any electromigration of carbon atoms. Our study unveils CTPG as an innovative system for practical utilization in graphene nanoelectronic and spintronic integrated circuits.

Automated Laboratory Kilogram-Scale Graphene Production from Coal.

The flash Joule heating (FJH) method converts many carbon feedstocks into graphene in milliseconds to seconds using an electrical pulse. This opens an opportunity for processing low or negative value resources, such as coal and plastic waste, into high value graphene. Here, a lab-scale automation FJH system that allows the synthesis of 1.1kg of turbostratic flash graphene from coal-based metallurgical coke (MC) in 1.5h is demonstrated. The process is based on the automated conversion of 5.7g of MC per batch using an electrical pulse width modulation system to conduct the bottom-up upcycle of MC into flash graphene. This study then compare this method to two other scalable graphene synthesis techniques by both a life cycle assessment and a technoeconomic assessment.

Unveiling the electrochemical advantages of a scalable and novel aniline-derived polybenzoxazole-reduced graphene oxide composite decorated with manganese oxide nanoparticles for supercapacitor applications

In the quest for better supercapacitor performance, materials with high energy storage, rapid charge transfer and excellent charge-discharge capabilities are crucial. However, improving energy density and optimizing electrode materials for supercapacitors remains a challenge. Within this perspective, we developed a novel aniline-derived polybenzoxazole-reduced graphene oxide composite (Mn3O4-pBOA-rGO) for supercapacitor applications. An electrode for supercapacitor applications was then fabricated using the synthesized composite. Various characterization techniques, such as X-ray diffraction, scanning electron microscopy, Fourier transform infrared spectroscopy and nuclear magnetic resonance spectroscopy, were employed to analyze the structure of the material and cyclic voltammetry, electrochemical impedance spectroscopy and galvanostatic charge-discharge tests were performed to evaluate the supercapacitive performance. Remarkably, the Mn3O4-pBOA-rGO ternary nanocomposite-based electrode exhibited enhanced electrochemical performance achieving an energy density of 116 Wh kg−1 in a 1 M aqueous Na2SO4 electrolyte at a current density of 1 A g−1. In comparison, the Mn3O4-pBOA binary nanocomposite recorded an energy density of 25 Wh kg−1, while bare Mn3O4 yielded 10 Wh kg−1. The significantly improved electrochemical properties of the Mn3O4-pBOA-rGO composite present a promising and viable solution for supercapacitor applications.

High-orientation, defect-rich and porous graphene films for excellent electromagnetic shielding and thermal management

With the rapid development of portable electronics, the demand for flexible shielding and thermal management materials is increasing steadily. Herein, we reported a scalable flexible graphene film preapred following hydrogen iodide chemical reducing and graphitization thermal reducing. Benifitting from the coordinated reduction, the fabricated graphene film is equipped with varous characteristics of high orientation, rich defect and three-dimensional porosity. Then the graphene film deliver outstanding mechanical property and electrical conductivity (1.2 × 105 S m−1). Moreover, superior electromagnetic interference (EMI) and thermal conductivity are realized compared with the simplex thermal reduction. The EMI effectiveness can reach a high value of 70 dB when the thickness is only 35 μm, and the specific EMI effectiveness is 380 dB/g cm−3. And the relationship between the effectiveness and structure parameters (thickness and density) is uncovered. The thermal conductivity could be up to 864 W m−1 K−1. This research may not only provide a new avenue to the development of flexible shielding and thermal management materials, but also promote the application of graphene.

Interfacial modification of GO-FePt hybrid film leads to giant ultrafast optical nonlinearity

Excellent optical nonlinearity is highly promising for the development of multifunctional ultrafast photonics techniques and integrated optoelectronic devices. However, existing numerous optical materials commonly suffer from several challenges, such as bad functional integration, slow response speed, and weak optical nonlinearity thus severely hindering their extensive applications. Here, we first engineer new scalable graphene oxide (GO)-FePt films by chemistry induced self-assembly and then demonstrate the enhanced ultrafast optical nonlinearity by resorting to their interfacial modifications. It is found that the FePt magnetic nanoparticles (NPs) are easily assembled on the surface of the GO by exchanging the surface ligands of the former with evaporated solvent, leading to good water solubility and super-paramagnetism. The femtosecond Z-scan test results show that both the nonlinear saturation absorption and optical Kerr refraction of the pure GO are subjected to reversion once the FePt NPs are introduced. More importantly, we can greatly enhance the ultrafast nonlinear optics response of as-prepared GO-FePt hybrid film by promoting the concentration of magnetic NPs. In addition, the associated optical nonlinearity can be further boosted with femtosecond vectorial beams excitation instead of the linearly polarized one. In principle, the enhanced optical nonlinearity may arise from direct metal-to-semiconductor interfacial charge transfer transition (DICTT) related to the difference in work function and Fermi level together with complicated interaction between the vectorial light fields and the hybrid films. The GO-based magnetic hybrid films with giant ultrafast optical nonlinearity have potential wide-ranging applications in integrated optoelectronics, ultrafast nanophotonics, opto-magnetic storage, and beyond.

Scalable graphene sensor array for real-time toxins monitoring in flowing water

Risk management for drinking water often requires continuous monitoring of various toxins in flowing water. While they can be readily integrated with existing water infrastructure, two-dimensional (2D) electronic sensors often suffer from device-to-device variations due to the lack of an effective strategy for identifying faulty devices from preselected uniform devices based on electronic properties alone, resulting in sensor inaccuracy and thus slowing down their real-world applications. Here, we report the combination of wet transfer, impedance and noise measurements, and machine learning to facilitate the scalable nanofabrication of graphene-based field-effect transistor (GFET) sensor arrays and the efficient identification of faulty devices. Our sensors were able to perform real-time detection of heavy-metal ions (lead and mercury) and E. coli bacteria simultaneously in flowing tap water. This study offers a reliable quality control protocol to increase the potential of electronic sensors for monitoring pollutants in flowing water.

Impact performance on industrial scalable graphene reinforcement composites

Carbon fiber reinforced epoxy laminates are widely used in the design and manufacturing of aeronautical structures. Among different manufacturing procedures, resin transfer moulding (RTM) has emerged as a cost-effective alternative to prepregs manufactured in an autoclave. However, the laminate obtained by RTM exhibits approximately 20% lower mechanical properties. To address this limitation, the addition of nanoparticles has been suggested as a solution. In this study, graphene particles were obtained by in-situ mechanical exfoliation in the resin and directly injected into the mould. The major achievement of this study is that the entire manufacturing process was performed at an industrial scale using the same tooling used to produce aircraft structures. Laminates with varying concentrations and dispersion times were manufactured using RTM and subjected to compression after impact tests, resulting in a 7.6% improvement. Furthermore, analysis through SEM techniques revealed the role of graphene in the bear capacity of the laminates. Finally, to demonstrate the feasibility of the proposed methodology in an industrial environment, a real aircraft structure was manufactured with graphene, without any modifications to the actual industrial process.

Flow-Assisted Ultrasonic Exfoliation Enabling Scalable and Rapid Graphene Production for Efficient Inkjet-Printable Graphene Ink

Achieving high efficiency in graphene production and printing process simultaneously is challenging, but it needs to be addressed as it is critical for realizing the commercial viability of printed graphene devices. This study successfully substantiates these requirements by significantly improving the efficiency of graphene production and subsequently developing an inkjet-printable graphene ink that enables the rapid formation of the percolation network of graphene flakes. The integration of a flow coil reactor into an ultrasonic bath results in scalable and rapid graphene production, with graphene productivity up to three orders of magnitude higher than conventional liquid-phase exfoliation (LPE), offering the potential that ultrasonic LPE can benefit the scalability and simplicity of graphene production. In addition, the graphene ink, optimized by ink formulation, has a stable high graphene concentration of 3.5 g L–1, resulting in the formation of stable percolation networks of graphene flakes only after two printing passes under optimized printing conditions. The printed graphene patterns are also confirmed to be conformable to various substrates and durable against repeated stretching and bending stress. By ensuring high efficiency in graphene production and inkjet-printable ink preparation, this study would promote the commercialization of graphene production and the resulting printed graphene devices.

Facile synthesis of nitrogen-doped porous graphene for efficient adsorption of tetracycline: Behavior and mechanism

Developing economic and efficient adsorbents is critically important for antibiotic residual removal from contaminated water. Here, Nitrogen-doped porous graphene-like carbon (NPGC) adsorbents were successfully synthesized by self-blowing and doping method, where glucose was used as the carbon source, zinc nitrate was acted as the nitrogen source and the derived ZnO was as the porogen. The obtained NPGC possessed a graphene-like porous structure with moderate nitrogen doping. The removal capacity of NPGC was as high as 451.2 mg g−1 in 50 mg L−1 TC solution, which is much higher than graphene, carbon nanotubes, and activated carbon, due to the larger specific surface area and micro/mesopores on graphene sheets. The adsorption isotherms and kinetics for TC onto NPGC were well-fitted with Langmuir model and pseudo-second-order model. The adsorptive ability of NPGC increased linearly with the increasing graphitic N content due to the enhanced π-π interaction and hydrophobic effect between TC and NPGC. The NPGC also showed potential environmental application as revealed by anti-interference capacity in the interference (coexisting ions and humic acid) and reusability. This work not only provides a facile strategy to develop economic and scalable N-doped graphene, but also systematically studies the adsorption mechanism of TC onto N-doped carbon adsorbents.