Functionalization Of Graphene Research Articles

Revealing the role of interlayer spacing in radioactive-ion sieving of functionalized graphene membranes

Functionalization of graphene enables precise control over interlayer spacing during film formation, thereby enhancing the separation efficiency of radioactive ions in graphene membranes. However, the systematic impact of interlayer spacing of graphene membranes on radioactive-ion separation remains unexplored. This study aims to elucidate how interlayer spacing in functionalized graphene membranes affects the separation of radioactive ions. Utilizing polyamidoxime (PAO) to modify graphene oxide, we controlled the interlayer spacing of graphene membranes. Experimental results indicate that tuning interlayer spacing enables control of the permeation flux of radioactive ions (UO22+ 1.01 × 10−5–8.32 × 10−5 mol/m2·h, and K+ remains stable at 3.60 × 10−4 mol/m2·h), and the K+/UO22+ separation factors up to 36.2 at an interlayer spacing of 8.8 Å. Using density functional theory and molecular dynamics simulations, we discovered that the effective separation is mainly determined via interlayer spacing and the quantity of introduced functional groups, explaining the anomalous high permeation flux of target ions at low interlayer spacing (4.3 Å). This study deepens our comprehension of interlayer spacing within nanoconfined spaces for ion separation and recovery via graphene membranes, offering valuable insights for the design and synthesis of high-performance nanomembrane materials.

A fluorescent aptasensor based on functional graphene oxide and FRET strategy simultaneously detects aflatoxins B1 and aflatoxins M1

Simultaneous and rapid detection of various mycotoxins in food holds significant practical importance in the field of food processing and safety. In this study, a fluorescent aptasensor based on functionalized graphene oxide (FGO) is developed for simultaneous detection of aflatoxin B1 (AFB1) and aflatoxin M1 (AFM1). The two aptamers specific to AFB1 and AFM1 are labeled with Cy3 and Cy5 respectively. Both the aptamers can be adsorbed onto the surface of FGO through π-π stacking, resulting in fluorescence resonance energy transfer (FRET) between the fluorophore and FGO. The absence of target leads to quenching of fluorescence while presence of either aflatoxin causes interaction between corresponding aptamer and target, leading to release from FGO surface thereby turning on fluorescence signal. The limit of detection (LOD) for AFB1 is determined as 8.7 pg/mL whereas for AFM1 it is found to be 20.1 pg/mL, demonstrating fast and sensitive detection capability using this approach. Furthermore, the aptasensor exhibits good specificity and selectivity even under influence from other common interfering toxins. With its simplicity in operation and portability features, this sensor has potential applications for establishing sensitive and portable on-site detection methods for various mycotoxins.

Asymmetric CapMix Device Exploiting Functionalized Graphene Oxide and SPEEK Coatings for Improved Energy Harvesting From Salinity Gradients

AbstractThis work investigated the possibility of using functionalized graphene oxide and sulfonated poly(ether ether ketone) coatings on activated carbons to obtain an asymmetric device suitable for Capacitive Mixing (CapMix) application. Herein the synthesis and fabrication procedures of both materials and electrodes are reported, together with a comprehensive list of electrochemical characterization techniques. The results from the electrochemical characterization are used to design the optimal operational parameters for CapMix experiments involving the materials being studied. A homemade cell is designed and fabricated for CapMix application by polymer micromachining. Electrochemical tests are conducted to optimize the process parameters and the results of this optimization are reported, proving that both the materials and the process parameters play a key role in CapMix. The final device can generate a net power output of 12 mW m−2 by mixing simulated seawater and freshwater. This result paved the way for further application of graphene oxide in the field of renewable energy.

Wet-Spinning Assembly of Flexible, Ultratough, and Conductive Alkali Lignin Functionalized Graphene Oxide Composite Fibers for Fiber-Shaped Supercapacitor

Wet-Spinning Assembly of Flexible, Ultratough, and Conductive Alkali Lignin Functionalized Graphene Oxide Composite Fibers for Fiber-Shaped Supercapacitor

Numerical analysis of polyethylene based nano-enhanced phase change material in cylindrical storage system

Environmental sustainability encompasses various dimensions like waste management, energy conservation, and environmental impact. The use of waste plastic; Linear Low-density polyethylene (LLDPE) as a phase change material (PCM) offers a sustainable solution for energy and the environment. This study investigates LLDPE/ functionalize graphene composites for latent heat storage using a shell and helical coil for effective energy conversion. The simulation is carried out for constant flux and constant temperature heat supply to understand the influence of nano additives and geometrical parameters such as spiral coil diameter (Dc ), pitch (Pc ), and orientation of storage unit (θ). The result reveals that nano additive influence effectively and reduces the charging time approximately from 20 to 40% for 1–5% of nano-addition. Simulation results reveals that the spiral coil diameter is crucial for melting and heat transmission. The overall melting time is decreased by up to 56% by increasing the spiral coil diameter from 21 to 49 mm for LLDPE while the effect of pitch length variation is found not significant. The constant temperature heating at 160, 250 and 340°C gives effective results for charging time improvement. The geometrical orientations from 0 to 90 degrees report that the horizontal position is the best orientation for energy storage.

Polyimide nanocomposites for high‐temperature capacitive energy storage applications by incorporating functional graphene oxide nanosheets: Design, preparation, and mechanism

AbstractHerein, graphene oxide (GO) and its derivative, reduced GO (rGO) and p‐phenylenediamine (PPD) functionalized GO (GO‐g‐PPD) were first synthesized and selected as dielectric fillers, and then GO/polyimide (PI), rGO/PI, and GO‐g‐PPD/PI dielectric nanocomposites were fabricated through in situ polymerization‐composition strategy. Fourier transform infrared, Ram, and x‐ray diffraction analysis confirmed the success synthesis of rGO and GO‐g‐PPD dielectric fillers. The mechanical properties showed that GO‐g‐PPD/PI nanocomposites exhibited the highest tensile strength and elasticity modulus. TGA analysis revealed that the enhancement of thermal stability by addition of dielectric fillers. The dielectric constant of 2.5 wt.% GO‐g‐PPD/PI nanocomposites reached 25.05, which was 8.55 times that of pure PI (2.93). Energy storage performance tests showed that the energy storage density of GO‐g‐PPD/PI containing 2 wt.% filler reached 0.77 J/cm3, which was 71% higher than pure PI. These findings underscore the potential of GO derivative as a cost‐effective reinforcement for PI dielectric nanocomposites for high‐temperature capacitive energy storage applications.

Novel palladium nanoparticles/4-aminophenol functionalized nitrogen-doped graphene quantum dots-based nanocomposite electrochemical sensor: Synthesis, characterization, capacitance, and dopamine sensing

In this study, an ultrasensitive electrochemical sensor based on palladium nanoparticles/4-aminophenol functional nitrogen-doped graphene quantum dots (PdNPs/4AP N-GQDs) composite was fabricated to detect dopamine (DA). The sensor was characterized by FTIR, UV–Vis, TEM, EDX, and XRD methods. The electrochemical analysis of the nanocomposite modified glassy carbon electrode (GCE) was conducted by cyclic voltammetry (CV). HOMO-LUMO energy levels and band gap energy was calculated from cyclic voltammograms, and the band gap energy was found to be small at 0.06 eV. The electrode reaction properties of dopamine on this developed ultrasensitive electrode were investigated by CV and differential pulse voltammetry (DPV), which showed that the electrode had electrocatalytic activity for dopamine sensing. Moreover, the developed electrode exhibited good sensitivity and improved performance, and the linear calibration curve for dopamine was calculated to have a LOD (limit of detection) of 21 pM in the range of 250 pM to 10 nM. Finally, the selectivity of the GQDs nanocomposite modified GCE towards dopamine was studied in the presence of several bioactive compounds with inhibitory effects. In addition, the specific capacitance of the nanocomposite material at 5 mV s−1 was found to be as high as 0.777F g−1. Furthermore, the dopamine selectivity of the sensor among some organic and inorganic interfering bioanalytes was investigated and the sensor was found to have excellent DA selectivity despite the bioanalytes.

Fracture behavior of graphene with intrinsic defects and externally introduced defects

Introducing and regulating defects to prepare functional graphene has become a research hotspot. However, most studies focus on the mechanical properties of functional graphene or the influence of a single defect, which cannot reflect the influence of multiple coupled defects on mechanical properties. In this study, molecular dynamics methods were used to investigate the fracture behavior of graphene under the coupled effects of intrinsic defects such as vacancies, cracks, and topological defects, as well as external introduced defects such as epoxy groups and hydroxyl groups. The results showed that the fracture behavior of graphene is strongly related to the defects' type, concentration, and functionality. Under the same conditions, the epoxy group has the strongest leading effect on fracture, followed by cracks, Stone-Wales topological defects, and hydroxyl groups. Based on the tensile simulation of defect-ordered graphene, the critical relative concentrations and functionalities of different defect types leading to fracture were further quantified and validated using an amorphous distribution model. In addition, the fracture mode dominated by epoxy groups is related to its functionality. Excessive or insufficient functionality will exhibit strong brittle fracture characteristics, and when the functionality is at a certain threshold, it will exhibit obvious ductile fracture characteristics; while hydroxyl-dominated fracture presents brittle mode. Finally, the coupled fracture mechanism was analyzed from the aspects of bonding characteristics and system energy. The research results can provide reference and reference for the theoretical research and technological development of graphene.

Highly adsorptive removal of heavy metal, dye, and antibiotic pollutants using functionalized graphene nanosheets sono-electrochemically derived from graphitic waste

The development of highly adsorptive materials at low cost is critically important for efficient treatment of industrial wastewater. We herein report a one-step sonoelectrochemical strategy to synthesize functionalized graphene (FG) nanosheets as an effective adsorptive material using graphite waste from spent household batteries. Scanning/transmission electron and Raman microscopy studies reveal that the as-synthesized nanosheets are composed of few (2–6) graphene layers. Additionally, Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy analyses imply the presence of oxygen functional groups on the nanosheets (CO and -COOH, oxygen content of 4.29%), which are immensely beneficial for the electrostatic adsorption with heavy metals, dyes, and antibiotics in aqueous solutions. As expected, FG nanosheets exhibit potent capabilities of handling a wide range of pollutants, such as methylene blue, methyl orange, enrofloxacin, and Pb2+, with high adsorption performances (99.95% and 21.21 mg/g for Enrofloxacin, 98.93% and 119.3 mg/g for methylene blue, 95.82% and 25.67 mg/g for methyl orange, 95.56% and 86.10 mg/g for Pb2+). These findings therefore show a great promise for practical uses of the FG material as efficient adsorbents in eliminating metallic, organic, and antibiotic pollutants in water.

Design and Fabrication of Silver Nanoparticles Doped β-cyclodextrin-chitosan Functionalized Graphene Nanocomposite Modified Electrode for Determination of Cu(II)

Introduction: In this study, a nanocomposite film was prepared by doping silver nanoparticles onto β-cyclodextrin-chitosan functionalized Reduced Graphene Oxide (RGO), denoted as Ag/ β-CD/CS/G nanocomposite. The average diameter of the Ag NPs was found to be 62±17 nm. Methods: The fabricated composite was applied to monitor trace levels of copper ions in different industrial and environmental water samples. The morphology and microstructure of the fabricated sensor were extensively investigated using different techniques, including XRD, TGA, HR-TEM, FTIR, SEM, XPS, and EDX physicochemical techniques. For the electrochemical monitoring of Cu(II), the Ag/β-CD/CS/G nanocomposite electrode showed remarkable performance in terms of high sensitivity and a low limit of detection that was found to be 0.24 nmol L-1. Results: The developed sensors showed a linear dynamic range from 10-3 to 10-8 mol L-1 with an R2 of 0.99. The impacts of different electrochemical parameters, including medium pH, scanning rate, and interfering ions, were investigated. Conclusion: Furthermore, the fabricated modified electrode showed high efficiency for Cu(II) detection in groundwater samples.

Oxygen ion irradiation: Insights into the structural modifications of CVD-grown graphene

To enhance graphene's functionalities and explore potential applications, modifying its structure through ion irradiation has evolved as a favorable method. In the present study, graphene film grown on a copper substrate was transferred to a SiO2/Si substrate for conducting oxygen ion irradiation experiment at 100-keV. The research investigates the impact of varying oxygen ion fluences on CVD-grown graphene films. Characterization through Raman spectroscopy, confirmed increased D peak intensity and alterations in the 2D peak at higher fluences, indicating defects and lattice distortion induced by irradiation.

From carbon nanotubes to functional graphene nanoribbons for high performance supercapacitors

Graphene nanoribbons (GNRs) have great application potential as electrode materials for supercapacitor because of their edge-enriched active surface area, excellent conductivity and unique structure. Here, functional GNRs were prepared by the oxidation unzipping of carbon nanotubes (CNTs) with followed low-temperature heat treatment. Benefiting from the unique one-dimensional structure, a large number of oxygen functional groups (14.41 at.%), and superior specific surface area (184.44 m2 g−1), the optimized GNR-200 electrode achieves a high specific capacitance of 225.9 F g−1 at 0.5 A g−1, which is five times better than that of pure CNTs (39.6 F g−1). Most importantly, the assembled GNR-200//GNR-200 symmetric supercapacitor delivers an energy density of 15.52 Wh kg−1 and good electrochemical stability with the capacitance retention of 92.85 % after 20,000 cycles.

Antibacterial Activity and Optical Behavior for Restoration of Micro and Nano Dental Fillers Using Functional Graphene Nanosheets with Polymethyl Methacrylate

Antibacterial Activity and Optical Behavior for Restoration of Micro and Nano Dental Fillers Using Functional Graphene Nanosheets with Polymethyl Methacrylate

Functional nanoporous graphene superlattice

Two-dimensional (2D) superlattices, formed by stacking sublattices of 2D materials, have emerged as a powerful platform for tailoring and enhancing material properties beyond their intrinsic characteristics. However, conventional synthesis methods are limited to pristine 2D material sublattices, posing a significant practical challenge when it comes to stacking chemically modified sublattices. Here we report a chemical synthesis method that overcomes this challenge by creating a unique 2D graphene superlattice, stacking graphene sublattices with monodisperse, nanometer-sized, square-shaped pores and strategically doped elements at the pore edges. The resulting graphene superlattice exhibits remarkable correlations between quantum phases at both the electron and phonon levels, leading to diverse functionalities, such as electromagnetic shielding, energy harvesting, optoelectronics, and thermoelectrics. Overall, our findings not only provide chemical design principles for synthesizing and understanding functional 2D superlattices but also expand their enhanced functionality and extensive application potential compared to their pristine counterparts.

Application Research Progress of Nanomaterial Graphene and its Derivative Complexes in Tumor Diagnosis and Therapy.

Functional nanomaterial graphene and its derivatives have attracted considerable attention in many fields because of their unique physical and chemical properties. Most notably, graphene has become a research hotspot in the biomedical field, especially in relation to malignant tumors. In this study, we briefly review relevant research from recent years on graphene and its derivatives in tumor diagnosis and antitumor therapy. The main contents of the study include the graphene-derivative diagnosis of tumors in the early stage, graphene quantum dots, photodynamics, MRI contrast agent, acoustic dynamics, and the effects of ultrasonic cavitation and graphene on tumor therapy. Moreover, the biocompatibility of graphene is briefly described. This review provides a broad overview of the applications of graphene and its derivatives in tumors. Conclusion, graphene and its derivatives play an important role in tumor diagnosis and treatment.

Defect-guided self-tearing in graphene

The two-dimensional to three-dimensional configuration transition through self-tearing promises the engineering and promising applications of graphene. However, it is challenging to control the tearing path on demand through common thermal and interfacial treatments. In this manuscript, a defect-guided self-tearing technique is proposed to generate wider, longer, and even curved and serrated configurations, which is impossible for defect-free graphene. The underlying tearing mechanisms regarding the advancing displacement are disclosed through molecular dynamics simulations and theoretical model. This study provides a useful guidance to the implementation of complex and functional three-dimensional graphene structures.

Enzyme encapsulation into zeolitic imidazolate framework-8/graphene oxide (ZIF-8/GO) for enhanced stability and DNA-mediated catalytic performance

A long-standing challenge for natural enzyme based catalysis is low stability under harsh conditions. We herein demonstrated a de nova approach to synthesize an enzyme encapsulated in ZIF-8/GO (HRP@ZIF-8/GO). The hybrid coating of ZIF-8/GO could provide HRP with tolerance towards various harsh environments (e.g.in the presence of proteolytic or chemical agents or at high temperature), as well as increased apparent substrate affinity. The feasibility of this biomimetic strategy for biostorage, enzyme cascades, and biosensing was also verified. Furthermore, owing to the introduction of functional graphene, the immobilized HRP displayed DNA-mediated controllable peroxidase (POD) activity, which was further employed to establish universal colorimetric aptasensor using antibiotic as model analyte. With this method, more analytical and biomedical applications of fragile enzymes can be exploited at extreme conditions, and it may also inspire other strategies to apply natural enzymes into industrial catalysis processes.

Design and synthesis of ammonia-modified reduced graphene oxide possessing more amino groups for methylene blue adsorption

To obtain a high-performance functional graphene with more amino groups, chlorine-functionalized reduced graphene oxide (RGO) reacts with ammonia.

Bio-inspired interfacial chemistry for the fabrication of a robust and functional graphene oxide composite film.

A strong and functional artificial nacre film is developed by using polyethyleneimine-functionalized GO (PEI-GO) and pyrogallol (PG) inspired by insect exoskeleton sclerotization. PEI-GO is macroscopically assembled into the laminated films and then reacted with PG under the optimized condition for their efficient cross-linking through Schiff-base reactions. The internal structure and physicochemical properties of PG-treated PEI-GO (PG@PEI-GO) films are systematically explored with various analytical tools. The optimized PG@PEI-GO films exhibit excellent tensile strength, modulus, and toughness of 216.0 ± 12.9 MPa, 17.0 ± 1.1 GPa, and 2192 ± 538.5 kJ m-3 which are 2.7, 2.8, and 2.3-fold higher than those of GO films, respectively. Furthermore, silver nanoparticles (AgNPs) are densely immobilized on the PG@PEI-GO films harnessing their abundant amine groups, and the AgNPs immobilized PG@PEI-GO films exhibit a high catalytic activity in the conversion of 4-nitrophenol (4-NP) to 4-aminophenol (4-AP) with maintaining structural integrity. Based on the results, we demonstrate that the rational design of interfaces, inspired by natural materials, is an efficient approach to achieving strong and functional GO laminated composite films.

Ice crystal guided folding of graphene oxides in a confined space: a facile approach to 1D functional graphene structures.

The controlled conformational changes of planar graphene nanosheets are of great importance to the realization of their practical applications. Despite substantial effort in the area, the controlled folding of two-dimensional (2D) graphene sheets into one-dimensional (1D) structures still remains a significant challenge. Here, for the first time, we report an ice crystal guided folding strategy to fabricate 1D folded graphene nanobelts (FGBs), where the formation and growth of ice crystals in a confined space function to guide the folding of 2D graphene oxide (GO) nanosheets into 1D nanobelts (i.e. folded graphene oxide belts, FGOBs), which were subsequently converted to FGBs after annealing. Thin aqueous GO containing films were obtained by blowing air through a GO dispersion in the presence of a surfactant, polyoxypropylenediamine (D400), resulting in a foam containing uniform air bubbles. Subsequent shock cooling of the foam using liquid nitrogen resulted in the facile fabrication of FGOBs. This technique provides a general approach to encapsulate catalytic nanomaterials such as Fe3O4 nanorods, TiO2 and Co3O4 nanoparticles into the folded graphene structure for practical applications such as Li-ion batteries.