Graphene Composite Materials Research Articles

Structural regulation of 1T-MoS2/Graphene composite materials for high-performance lithium-ion capacitors

Heterogeneous composite structures are considered an effective strategy by utilizing the advantages of heterogeneous components. However, the relationship between structural modifications and electrochemical performance remains inadequately understood. In this study, we leveraged DFT calculations to elucidate the key advantages of the 1T-MoS2/Gr heterostructure, including its exceptional electrical conductivity, enhanced Li+ adsorption capabilities, and improved Li+ diffusion kinetics. To synthesize the 1T-MoS2/Gr composite, we developed a facile, one-step hydrothermal method using glucose as a reducing agent, achieving an optimal heterostructure that maximized the synergistic properties of the components. By comparing different levels of graphene content, the relationship between structural regulation and electrochemical performance has been studied, and a remarkably significant heterostructure composite material (1T-MoS2/Gr-0.8) was identified. As the anode material for lithium-ion batteries (LIBs), 1T-MoS2/Gr-0.8 presents excellent cycle performance with 467 mAh g−1 under the condition (0.5 A g−1, 600 cycles). Simultaneously, when assembling the lithium-ion capacitor (LIC) device with an activated carbon (AC) cathode, even at a high power density of 11.7 kW kg−1, the energy density of the 1T-MoS2/Gr-0.8//AC LIC is as high as 137.0 Wh kg−1. Moreover, the capacity retention rate remains at 89.9 % even after 2000 cycles at 2 A g−1, demonstrating its candidacy as a high-performance anode material for LICs.

The effects of crystal orientation and common coal impurities on electronic conductivity in copper–carbon composites

The electronic conduction properties of copper–graphene composite materials including common coal impurities are studied. Exploring the transport properties for three crystallographic orientations [(111), (110), and (100)] of copper in copper–graphene composites, a strong orientational dependence on electronic conductivity is shown. Graphene exhibits near-ideal registries for (111) and (110) orientations, forming a connected network between grains that enables efficient carrier transport. The influence of non-carbon elements: nitrogen (N), oxygen (O), and sulfur (S) in graphene, representing possible structures in coal-based graphene are investigated. N, O, and S in graphene negatively impact the composite’s electronic conductivity relative to pristine graphene. A new method is introduced for visualizing the spatial distribution of electrical conduction activity in materials using the square of the electronic charge density near the Fermi level, based on the work of Mott. We call this technique the N2 method.

2,6-Diaminoanthraquinone modified MXene (Ti3C2Tx)/graphene as the negative electrode materials for ionic liquid-based asymmetric supercapacitors

Due to insufficient energy density, supercapacitors (SCs) with preeminent-power and long cycle stability cannot be implemented in some practical applications. Exploring hybrid materials with redox activity to emerge high specific capacitance in ionic liquid (IL) electrolytes can solve this problem. Herein, we report a redox-organic molecule 2,6-diaminoanthraquinone (DAAQ) modified MXene (Ti3C2Tx)/Graphene (DAAQ-M/G) composite material. With the assist of graphene oxide (GO), MXene and graphene fabricate a three-dimensional (3D) interconnected structure as a conductive framework, which inhibits self-stacking of MXene monolayers and ensures high electronic conductivity. Meanwhile, DAAQ is loaded onto the M/G framework through covalent/non-covalent functionalization. The DAAQ as a spacer effectively enlarges the interlayer spacing of MXene nanosheets, and meanwhile produces reversible redox reactions during charge/discharge processes to provide additional Faradaic contribution to capacity. Therefore, the specific capacitance (capacity) of the DAAQ-M/G as the negative electrode material reaches to 226 F g-1 (306 C g-1) at 1 A g-1 in 1-ethyl-3-methylimidazolium tetrafluoroborate (EmimBF4) electrolyte. Furthermore, an asymmetric supercapacitor (ASC) is assembled using DAAQ-M/G as the negative electrode and self-prepared organic molecule hydroquinone modified reduced graphene oxide (HQ-RGO) material as the positive electrode, with a high energy density of 43 Wh kg-1 at high power density of 1669 W kg-1. The ASC can maintain 80% of initial specific capacitance after 9000 cycles. This research can provide better support to develop advanced organic molecules-modified MXene composite materials for ionic liquid-based SCs.

In situ TEM nanomechanical study on enhanced toughness of graphene-nanoparticle nanocomposite

Although theoretical studies and experimental research have shown outstanding mechanical properties of graphene, its brittleness and low toughness restrict its widespread industrial use. Here, we conducted a study to examine the impact of encapsulated Ag nanoparticles on the mechanical properties of graphene through in situ nanomechanical testing in an aberration-corrected transmission electron microscope (TEM). The presence of Ag nanoparticles was found to decrease crack propagation speed, enabling the TEM observation of crack deflection around the nanoparticles at nanoscale, as well as real-time measurement of the concomitant increase in stress. Using our nanomechanical testing data, we were able to quantitatively estimate the stress intensity factor, which serves as a measurement of fracture toughness for graphene, and then compared our results with previously reported values. We further discuss the role of nanoparticles in the propagation of cracks and their potential to enhance the toughness of materials. These findings have practical implications for the development of high-performance graphene composite materials.

Facile and economic preparation of graphene hydrothermal nanocomposite from sunflower waste: Kinetics, isotherms and thermodynamics for Cd(II) and Pb(II) removal from water

Keeping the need for good water quality and the demand of climatic issues, the sunflower waste was converted into graphene hydrothermal nanocomposite absorbents for the removal of toxic Cd(II) and Pb(II) metal ions from water. The graphene composite materials were studied by scanning (SEM) and transmission electron microscopy (TEM), XRD analysis, TG and DSC, Raman and IR spectroscopy. According to SEM and TEM analysis, the decarbonized materials had a disordered structure with amorphous carbon with a small pore content. During the carbonization process, the pores space was opened due to the removal of amorphous organic matter and the formation of defects; providing a significant number of meso- and micropores. The prepared graphene composite showed 133.33 and 222.22 mg/g Langmuir adsorption of Cd(II) and Pb(II) at pH 6.0, dose 0.33 g/30 mL, initial concentration 300 mg/L, time 30 min and at 45 °C temperature using hydrothermal nanocomposite HTC/graphene oxide absorbent. The obtained results followed the sorption of heavy metal ions in a mixed-diffusion mode with the contribution of a second-order reaction between the active center of the sorbent and the metal ions. The Temkin and Dubinin-Radushkevich model’s parameters and thermodynamic results confirmed endothermic physical interactions among adsorbent and metal ions. This paper is highly useful for managing sunflower waste and purifying water; leading to the present demand for clean water and climatic issues. The production of the effective low-cost nanocomposite using green synthesis technologies (hydrothermal carbonization of raw materials) is highly useful for the removal of Cd(II) and Pb(II) toxic metal ions from water.

Changes in Current Transport and Regulation of the Microstructure of Graphene/Polyimide Films under Joule Heating Treatment.

The excellent electrical properties of graphene have received widespread attention. However, the difficulty of electron transfer between layers still restricts the application of graphene composite materials to a large extent. Therefore, in this study, graphene/polyimide films were subjected to a Joule heating treatment to improve the electrical conductivity of the film by ~76.85%. After multiple Joule thermal cycle treatments, the conductivity of the graphene/polyimide film still gradually increased, but the increase in amplitude tended to slow down. Finally, after eight Joule heat treatments, the conductivity of the graphene/polyimide film was improved by ~93.94%. The Joule heating treatment caused the polyimide to undergo atomic rearrangement near the interface bonded to the graphene, forming a new crystalline phase favourable for electron transport with graphene as a template. Accordingly, a model of the bilayer capacitive microstructure of graphene/polyimide was proposed. The experiment suggests that the Joule heating treatment can effectively reduce the distance between graphene electrode plates in the bilayer capacitive micro-nanostructures of graphene/polyimide and greatly increases the number of charge carriers on the electrode plates. The TEM and WAXS characterisation results imply atomic structure changes at the graphene/polyimide bonding interface.

A novel process study of biomass-based graphene-enriched body based on selective laser sintering technology

Laser-induced graphene (LIG) on natural wood is a novel method for producing porous graphene composite materials with low cost and high efficiency. However, the three-dimensional (3D) fabrication of biomass-derived LIG remains challenging, restricting its applications in various domains. This paper introduces a “SCG” (sintering, carbonization and grapheneization) preparation strategy, which integrates selective laser sintering and multiple laser processes to achieve rapid fabrication of graphene-enriched structures from natural biomass materials with complex shapes. The experiment demonstrates that the sintering necks are preserved during the carbonization and graphitization process, maintaining the original interlocking state of the upper and lower layers. The laser power and irradiation times for producing porous graphene have an optimal range, beyond which the quality of the synthesized graphene deteriorates. This study validates the effectiveness of this method and investigates the optimal process parameters and application directions. This method not only offers a 3D fabrication technique for biomass-derived LIG for the first time, but also enables 3D printing of biomass carbon electrodes, which have the benefits of wide applicability, no need for activators, low cost, and high efficiency.

Micropore self-repairing/blocking by the rapid carbonization of MOFs/graphene for various sodium storage

Metal-organic framework materials (MOFs) and graphene composite materials are the promising anode for sodium ion battery due to the excellent specific performances. Introducing graphene gives MOFs the increased active sites and improved electronic conductivity, showing a positive effect for the overall enhancement of properties. In this work, different from the enhanced sodium storage capacity after introducing reduced graphene oxides into MOFs derived materials in previous researches, the micropore structures of MOFs/graphene composite materials in the same systems are repaired by a self-repairing/blocking process during rapid carbonization process, which thus hinders the diffusion kinetics of Na+ and decreases the sodium storage capacity negatively.

Effect of Graphene Particle Diameter on Mechanical Properties of Graphene Composite Material

In order to improve the mechanical properties of alloys and broaden their application fields, high-performance metal matric composites have received more and more attention. Graphene has excellent mechanical properties and is often used as a reinforcing phase for various composite materials. However, as the reinforcing phase of the composite, the number, shape, and size of graphene have a significant effect on the overall mechanical properties of the composites. Therefore, the influence of graphene particle diameter on the mechanical properties of graphene particle reinforced metal matrix composites was studied in this paper. By establishing a series of finite element models, we simulated the mechanical behaviour of composite materials under static tension loading. The relationship between graphene particle diameter and material mechanical properties is revealed.

Super Graphene-Skinned Materials: An Innovative Strategy toward Graphene Applications.

Super graphene-skinned materials are emerging members of the graphene composite materials family, which are produced through the high-temperature chemical deposition of continuous graphene layers on traditional engineering materials. The high-performance graphene "skin" endows the traditional engineering materials with additional functionalities, and atomically thin graphene films enter the market by hitching a ride on traditional material carriers. Beyond the physical coating of graphene powders onto engineering materials, the directly grown continuous graphene skin keeps its excellent intrinsic properties to a great extent and holds promise for future applications. Super graphene-skinned material is an innovative pathway for applications of continuous graphene films, which avoids the challenging peeling-transfer process and solves the non-self-supporting issue of ultrathin graphene film. It is a big family, including graphene-skinned powders, fibers, foils, and foams. With further processing and molding, we can obtain graphene-dispersed bulk materials, especially for metal-based graphene-skinned materials, which provides a creative pathway for uniformly dispersing graphene into a metal matrix. In practical applications, graphene-skinned materials would exhibit excellent performance with perfect processing compatibility with current engineering materials and be pushed to real industrial applications relying on the broad market of engineering materials.

Synergetic Adsorption of Dyes in Water by Three-Dimensional Graphene and Manganese Dioxide (PU@RGO@MnO2) Structures for Efficient Wastewater Purification

The improper discharge of industrial wastewater causes severe environmental pollution and the textile industry’s dye usage contributes significantly to industrial wastewater pollution. Hence, an effective method for removing the harmful substance methylene blue (MB) from dye wastewater is proposed. This method adopts a three-dimensional graphene composite material based on manganese dioxide (MnO2), named polyurethane@ reduced graphene oxide@ MnO2 (PU@RGO@MnO2). First, graphene is prepared with hydrazine hydrate as a reducing agent and polyurethane as a framework. MnO2 nanoparticles are synthesized by the reaction of potassium permanganate (KMnO4) with carbon. These nanoparticles are then loaded onto the three-dimensional framework to create the composite material. Finally, adsorption and removal experiments for MB are conducted to compare the performance of the composite material. The results indicate that the graphene based on the polyurethane framework exhibits favorable mechanical properties. The unique three-dimensional lattice structure provides abundant active sites for loading MnO2 nanoparticles, significantly increasing the contact area between the adsorbent and MB solution and thus improving the adsorbent utilization rate (reaching 94%). The nanoparticles synthesized through the reaction of KMnO4 with carbon effectively suppress the agglomeration phenomenon. Additionally, the introduction of dynamic adsorption and dynamic removal modes, aided by a water pump, substantially enhances the adsorption and removal rates, showcasing excellent performance. The research on a multi-porous three-dimensional structure holds significant practical value in water treatment, offering a new research direction for dye wastewater treatment.

Nitrogen, sulfur coordinated metal complex and reduced graphene oxide hybrid materials as counter electrodes for application in dye-sensitized solar cells

Graphene, as one of the carbon-based materials, is considered to be a potential replacement for platinum and has been widely used as a counter electrode in dye-sensitized solar cells to achieve low-cost and high electrocatalytic materials. In this work, we synthesized a nitrogen-sulfur-coordinated iron complex as a source of heteroatoms, and prepared iron-nitrogen-sulfur co-doped reduced graphene oxide (FeNS-rGO) composite material by mixing with different mass ratios of graphene oxide (GO) and thermal annealing under nitrogen at 400 °C. The sintered GO was transformed into rGO, which increased the conductivity of materials, while the doping of nitrogen and sulfur atoms enhanced the carrier mobility and conductivity of the material. The distribution of Fe on graphene also improved the catalytic performance of material. FeNS-rGO (5:1), used as the CE in DSSC, showed superior reduction catalytic activity for I−/I3− compared to platinum and demonstrated an excellent power conversion efficiency of 8.17 %, which outperformed platinum. This proves that the graphene composite material doped with iron, nitrogen, and sulfur has excellent performance and can be used as a substitute for platinum.

Controllable preparation of wrapped Fe2O3@rGO composites and their lithium ion storage performance

In this paper, reduced graphene oxides wrapped hollow Fe2O3 spheres (Fe2O3@rGO) were successfully prepared by solvothermal method. Results show that plenty of Fe-O-C bonds between reduced graphene oxides and Fe2O3 significantly improved electron transfer rate of the composite anodes, and confinement effect of reduced graphene oxides slowed the pulverization rate of Fe2O3 during charge/discharge process. As expected, wrapped structured Fe2O3@rGO anode exhibited high rate capability of 514 mA·h/g at high current of 5.0 A/g and durable cycling life over 500 cycles with a capacity of 987 mA·h/g under 0.5 A/g with a capacity retention of 81.1%. This work provides an effective strategy for the preparation of high-rate and long-life graphene composite anode materials.

Persulfate activation technology based on carbon-based catalyst for removal of phenolic pollutants from water

Phenolic compounds constitute a broad category of extensively utilized chemical entities, the environmental residue of which has elicited substantial concerns regarding its deleterious impacts on natural ecology and human health. Over the past years, persulfate-based advanced oxidation technology (PS-AOPs), attributable to its effective degradation capacity for organic contaminants in aqueous environments, has garnered increasing interest among the scientific community. Relative to metal-based catalysts, their carbon-based counterparts possess distinct advantages such as non-toxicity, robust pH adaptability, appropriate pore volume, and extensive specific surface area, and have thus found considerable applications in activating PS for the removal of phenolic pollutants in water. This article provides a comprehensive review of recent research advancements concerning the use of carbon-based catalysts— including graphene, activated carbon, biochar, and metal-carbon composite materials — for the activation of PS aimed at phenolic pollutant removal. Additionally, it suggests potential trajectories for future investigations in this field.

Application of Naphthoquinone Derivatives Non‐Covalently Modified Graphene Nanosheets in Asymmetric Supercapacitors

AbstractAs an organic pseudocapacitive active material, 2, 3‐Dichloro‐1, 4‐naphthoquinone (DNQ) was used in supercapacitors. Graphene with unique structures and high electrical conductivity acts as substrate. DNQ non‐covalently modified graphene composite material (DNQ@rGO) was synthesized through the simple solvothermal synthesis. The redox reaction between naphthol and naphthoquinone occurs on reduced graphene oxide(rGO), which forms an ideal pseudocapacitance without destroying its sp2 network. The optimal DNQ@rGO electrode material obtained the specific capacitance of 361.2 Fg−1 at 5 mV s−1 in 1 mol L−1 H2SO4 and exhibited excellent rate capability (capacitance retention of 87.5 % at 100 mV s−1) in the three‐electrode system. We also prepared holey layered oxygen‐rich graphene hydrogels (HLGH) material, whose electrochemical performance is superior to traditional three‐dimensional (3D) graphene hydrogels (GH). Finally, two asymmetric supercapacitors (ASCs) were assembled by using the DNQ@rGO (positive electrode), the HLGH and GH (negative electrode). The results show that the ASC with HLGH as negative electrode achieved the high energy and power densities due to the perfect matching of capacitance and kinetics between the positive and negative electrodes. The specific capacitance was almost no loss after 4700 cycles, showing the excellent stability.

Preparation and Properties of Nitrogen-doped Graphene Composite Carbon Materials Prepared from Different Nitrogen Sources

To get materials with better electrochemical properties, the physicochemical properties of nitrogen-doped graphene composite carbon materials prepared from different nitrogen sources are investigated in this paper. Nitrogen-doped graphene composite carbon materials with pyridine, urea, and melamine as nitrogen sources (NGpyridine, NGurea, and NGmelamine) were prepared by electrospinning and post-heat treatment. The results show that graphene exists in all three kinds of composite carbon fibers in the form of multi-layers. The NGmelamine fibers have more defects, the distribution of NGpyridine fibers is more uniform and the diameter of NGpyridine fibers is mostly concentrated in 270-330 nm. The maximum current density of NGpyridine is 27.51 mA/cm2, that of NG urea is 8.99 mA/cm2, and that of NGmelamine is 2.24 mA/cm2. In comparison, NGpyridine shows better electrochemical performance.

Multifunctional Actuator Based on Graphene/PDMS Composite Materials with Shape Programmable Configuration and High Photothermal Conversion Capability.

Photoresponsive smart actuators based on carbon materials are attracting increasing attention. However, the low content of carbon materials currently limits the development of carbon material actuators. In this work, we designed and prepared a multifunctional bilayer composite actuator with controllable structures and high photothermal conversion efficiency. The actuator consists of a graphene/polydimethylsiloxane (PDMS) composite layer and a PDMS layer. With an ultrahigh graphene mass fraction (30%), the actuator exhibits a good hydrophobicity, unexpectedly high photothermal conversion performance (from room temperature to 120 °C within 1 s), and rapid photo-response capability. By thermal regulation, ultraviolet laser cutting, and assembly, the actuator can achieve shape programmable configuration in three-dimensional directions. Bionic crawling robots achieve a crawling speed of 0.065 mm/s, and liquid tracking robots achieve a rotational motion of 106°/s, a linear motion of 8.42 mm/s, and a complex "W"-shaped trajectory motion. This work provides a simple and effective method for the preparation and realization of multifunctional actuators based on graphene composite materials.

Surface charge induced self-assembled nest-like Ni3S2/PNG composites for high-performance supercapacitors

The paper presents a self-assembly approach to synthesize Ni3S2/N, P co-doped graphene (PNG) composite electrode materials for supercapacitors with high energy storage performance and structural stability. Innovatively, the self-assembly approach is induced via the surface charge effect utilizing a two-step hydrothermal method. The doping of nitrogen (N) and phosphorus (P) atoms regulates the surface charge distribution on graphene nanosheets. Therefore, in the synthesized Ni3S2/PNG heterostructures, Ni3S2 nanowires are interwoven into nests and uniformly attached to PNG. The design of the electrode materials with such a special structure not only supports each other to improve the stability of the materials but also facilitates the rapid diffusion of electrolyte ions. Based on the advantages of composition and structure, Ni3S2/PNG has a high specific capacitance of 1117C g−1 at a current density of 1 A/g and excellent rate performance. The asymmetric supercapacitors (ASC) assembled with Ni3S2/PNG and PNG as positive and negative materials respectively have a high energy density of 62 Wh kg−1 at a power density of 158 W kg−1.

Highly Sensitive and Flexible Copper Oxide/Graphene Non‐Enzymatic Glucose Sensor by Laser Direct Writing

AbstractAccurate and convenient detection of human blood glucose levels is an effective method for early diagnosis of diabetes and prevention of complications. The flexible and wearable electrochemical glucose sensor with low cost, fast responsiveness, good stability, reliability, and high sensitivity has attracted much attention in monitoring glucose concentration. The preparation of a conductive layer with catalytic activity on a flexible substrate is the key to making a wearable glucose sensor. Here, graphene composite materials sintered with copper oxide (CuO) nanoparticles are successfully prepared on a polyimide film by laser direct writing method and fabricated a flexible non‐enzymatic glucose sensor using laser‐engraved graphene (LEG) as a conductive electrode. The CuO/LEG sensor exhibits a high sensitivity of 619.43 μA mm−1 cm−2 in 0–3 mm glucose and 462.96 μA mm−1 cm−2 in 0–8 mm glucose. In addition, the CuO/LEG sensor shows good reproducibility, high anti‐interference capability, and long‐term stability. It also presents good bending stability, which can maintain 82.40% initial current after 100 times bending. Moreover, the CuO/LEG sensor has an obvious step‐ampere response in the detection of sweat samples, indicating the great potential of wearable sweat sensors.

Metal–organic framework and graphene composites: advanced materials for electrochemical supercapacitor applications

Bridging the properties of MOFs and graphene and the development of MOF–graphene composite materials has the potential to extend their usage in supercapacitors and serve as a valuable resource for further investigation.