Graphene Oxide Hybrid Research Articles

PVDF composite fibers for wireless fall-alert detection

As the demand for healthcare devices continues to rise, novel technologies centered on personalized motion monitoring systems are being developed, wherein wearable sensors play a pivotal role. In the present investigation, an innovative wireless apparatus for detecting falls is introduced, which encompasses a specifically engineered pressure sensor composed of polyvinylidene fluoride (PVDF) composite fibers. Our design consists of high β-phase content of electrospun composites including 0.1 wt% of zinc oxide/reduced graphene oxide (ZnO/rGO) hybrid (mass ratio 90/10) which shows enhanced electrical voltage of 11.36 ± 0.72 V compared to pristine PVDF fiber. This piezoelectric pressure sensor is integrated with a wireless embedded system capable of transmitting an “SOS” message to a mobile phone upon the user’s fall experience. Such wearable fall alert detection systems with improved characteristics could benefit the elderly and patients requiring continuous monitoring for possible falls.

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.

2D covalent organic framework/reduced graphene oxide hybrid hydrogel for simultaneous power generation and organic contamination degradation in microbial fuel cell

Microbial fuel cells (MFCs) are promising devices that convert chemical energy into electrical energy via extracellular electron transfer between bacteria and electrodes. However, inefficient extracellular electron transfers and bacteria/electrode interactions often limit their performance. Herein, we demonstrate a hybrid hydrogel assembled by a 2D covalent organic framework (COF) and reduced graphene oxide (rGO) nanosheets as anode materials for MFCs. The 2D COF nanosheets effectively prevent the stacking of rGO nanosheets, resulting in the hybrid hydrogel with a high specific surface area (313.2 m2/g), abundant mesopores and macropores, and high electrical conductivity (492 S/m). The COF material also brings many quinone groups as redox mediators to facilitate electron transfer between bacteria and electrodes. The COF/rGO hybrid hydrogel enhances the growth of Shewanella decolorationis S12 cells, even under the influence of different organic dyes. Dense biofilms are formed on the hybrid hydrogel's surface and inside its macropores, further improving extracellular electron transfers. Assembled MFCs using COF/rGO anodes deliver a maximum power density of 905.1 mW/m2 and can operate for 600 h. They also enable simultaneous power generation and fast organic contamination degradation in electrolytes. This work shows the potential of using 2D nanoarchitectures to promote high-performance MFCs.

Experimental and theoretical evaluations on the parallel-aligned graphene oxide hybrid epoxy composite coating toward wear resistance

A Polyethyleneimine functionalized graphene oxide (GO) hybrid epoxy resin composite coating was prepared by electrophoretic deposition technology to construct the parallel-aligned GO in the coating toward high-performance friction/wear resistance. Results from experiments and molecular dynamics clarify that the addition of parallel-aligned GO into epoxy coating can significantly reduce the wear rate up to 71%. Meanwhile, its Young's modulus, shear modulus and bulk modulus were strengthened by 70%, 36%, and 65%, respectively, with pure epoxy coating as a comparison. The improvement in composite coating's mechanical and tribological properties is attributed to the strong interaction between the functionalized-GO and the matrix, as well as the efficient barrier effect from the parallel arrangement of functionalized-GO. The parallel-aligned GO can effectively prevent the coating from cracking and flaking, improve mechanical qualities and produce the tribo-protective film, resulting in high load-carrying and wear resistance capabilities. Our work provides effective guidance for designing nanocomposites with long-term durability.

Bismuth-magnesium-oxide-based graphene oxide hybrid film for liquid crystal device application

Hybrid films containing bismuth magnesium oxide (BiMgO) and graphene oxide (GO) are investigated in this study. Solution-processed brush coating is used to fabricate the hybrid films, with the graphene oxide weight ratios adjusted to 0, 5, and 15%. The hybrid films show more stable and higher optical transmittances than the pure BiMgO film. A directional micro/nanogroove structure is observed on the hybrid film surface, which is derived from the shear stress during the brush-coating process; this anisotropic structure is used as a uniform liquid crystal (LC) alignment layer. Uniform and homogeneous LC alignment is then demonstrated via polarized optical microscopy and pretilt angle analyses, along with perfect light-control performance. Enhanced LC polar anchoring energy and hysteresis-free characteristics are observed for the brush-coated hybrid film as the GO-doping concentration is increased. Based on this perspective, the BiMgO-based GO hybrid film achieved via brush coating has potential for applications in next-generation LC systems.

A comparison study of the strengthening effect of carbon nanomaterial reinforcements in the 3D skeleton-reinforced copper matrix composites

The interfacial bonding and efficient load transfer are the research focus of the carbon nanomaterials (CNMs) reinforced metal matrix composites. In this study, special structured copper composites with CNMs distributing in the 3-D skeleton (CNMs/Cuf®Cu) were designed and prepared. The open cell copper foams reinforced by carbon nanotubes (CNTs), reduced graphene oxide (RGO) or CNTs-RGO hybrid were prepared by electrodeposition with enhanced mechanical strength and acted as the reinforcing skeletons, and the pure copper phase with good ductility and conductivity was continuously filled in the foam pores through powder metallurgy. The 3-D skeleton reinforcing structure, network structured CNTs-RGO hybrid, grain refinement effect and the disordered interface with Cu2O interface products synergistically cause higher load transfer efficiency and result in improved mechanical properties for the CNTs-RGO/Cuf®Cu composite, which shows the ultimate tensile strength (UTS) of 382 MPa, fracture elongation of 43 % and electrical conductivity of 93.26%IACS.

Evaluation of thermoelectric properties of hybrid polyaniline nanocomposites incorporated with graphene oxide and zinc oxide with different morphologies

Thermoelectric materials have been the object of interest in energy demand, given their potential for heat capture and the possibility of conversion into electricity. Among the possible thermoelectric materials, polymeric ones have been investigated because they are durable, non-toxic, and reproducible. This work used polyaniline (PANI), a good conductivity polymer, as a matrix to prepare hybrid nanocomposites. Nanoparticles were incorporated into the PANI matrix via solution with m-cresol. Two types of novel nanoparticles were used: zinc oxide (ZnO) synthesized with morphologies of nanoneedles (n-ZnO) and nanoflowers (f-ZnO). Hybrids of graphene oxide (GO) and ZnO with these morphologies (GO/n–ZnO and GO/f–ZnO) were incorporated into the hybrid PANI nanocomposites. Thermal stability was evaluated by thermogravimetric analysis (TGA). An improvement in thermal stability was observed with increasing GO/ZnO nanoparticles, as well as a higher degradation of the polymer matrix for higher levels of ZnO nanoparticles. The absorption bands of nanoparticles and PANI were observed by Fourier infrared spectroscopy (FT-IR). The corresponding characteristic bands of the functional groups were well evidenced, reflecting the success in synthesizing thermoelectric nanocomposites. Those with hybrid nanoparticles (GO/ZnO) had higher values of electrical conductivity (10.8 and 10.5 S cm−1), while those with only ZnO nanoparticles had higher Seebeck coefficient values (166.4 and 67.4 μV K−1). The only one with the highest thermoelectric force factor was PANI/GO/n-ZnO, with a value of 14.79 μW m−1 K−2, which is 49.3 times greater than the pure polymer and 1.5 times greater than the PANI/n-ZnO nanocomposite.

Effect of Graphene Oxide and Silver Nanoparticle Hybrid Composite on Acinetobacter baumannii Strains, Regarding Antibiotic Resistance and Prevalence of AMP-C Production.

Background and Objectives: Growing antibiotic resistance among bacteria is a global issue that is becoming harder and more expensive to solve. Traditional treatment options are becoming less effective, causing more fatal outcomes of nosocomial infections. Since the development of new antibiotics has stagnated in the last decade, a novel approach is needed. Materials and Methods: Graphene-based materials are being developed and tested for various applications, and the medical field is no exception. We tested 98 clinical A. baumannii strains for antibiotic resistance, AMP-C production and the effectiveness of a graphene oxide and silver nanoparticle hybrid nanocomposite. The disc diffusion method was used to determine antibiotic susceptibility results. Antibiotic discs containing cefotaxime, cloxacillin and clavulanate were used to detect AMP-C production. The effectiveness of the GO-Ag hybrid nanocomposite was determined by counting colony forming units (CFUs) after a suspension of A. baumannii and the GO-Ag hybrid nanocomposite was plated on MH agar and incubated overnight to grow colonies. Results: In our research, we found that A. baumannii strains are resistant to the majority of commonly used antibiotics. Antibiotic resistance levels and AMP-C production can be factors, indicating the better effectiveness of the graphene oxide and silver nanoparticle hybrid nanocomposite. Conclusions: In this study, a GO-Ag hybrid nanocomposite was shown to have the potential to fight even the most problematic bacteria like A. baumannii.

Terahertz Attenuated Total Reflection Spectral Response and Signal Enhancement via Plasmonic Enhanced Sensor for Eye Drop Detection.

With chronic ocular diseases such as glaucoma and dry eye syndrome, patients have to apply eye drops over the long term. The therapeutic effects of eye drops depend on the amount of drug contained and the stability of the solution. In addition, contamination during usage and transport can also negatively affect the quality and efficacy of eye drops. The current techniques for the characterization of eye drops are often complicated and time-consuming. Developing a fast and non-invasive way of accurately measuring eye drop quality remains an ongoing challenge. The biggest challenge and primary prerequisite for the application of this new detection technique for eye drops is the obtention of a sufficient spectral response and resolvable signal, considering the large background signal contributed by water. In this work, we use terahertz (THz) attenuated total reflection (ATR) spectroscopy combined with a sensitive hybrid graphene oxide (GO) and carbon nanotube (CNT) thin-film sensors to obtain distinct THz spectral signals in commercial eye drops. Various commercial eye drop products have been tested, and we show that they can be differentiated via their spectral signals. Our results provide a solid foundation for the future fine analysis of eye drops and the detection of their quality. Furthermore, THz spectroscopy combined with GO/CNT films has significant potential and advantages for the non-destructive characterization of aqueous pharmaceutical products.

Organic-Inorganic hybrid membrane for simultaneous heavy metal removal at drinking water pollution concentration levels

This study proposes a novel approach for simultaneous removal of potentially toxic metals from contaminated drinking water. The strategy is based on multi-layer graphene oxide hybrid membranes made up of Fe3O4@amyloid fibrils nanoclusters intercalated into the graphene oxide sheets via flow through approach. The hybrid membrane outperforms the previously known graphene-based membranes with adsorption capacity in the range of 128–570 mg g−1 of material. The membrane's removal efficacy exceeds 99.9% in both low (150 µg/L) and high (10,000 µg/L) metal concentration regimes, representative of ground water and wastewater contamination and complies with WHO drinking water requirements. Following NSF/ANSI 42,53–2007a American Standard Regulations, samples with metal concentrations of 150 µg/L and 20 mg L−1 calcium coexisted at pH 6.5 ± 0.25, complete removal of heavy metals (100%) in the effluent was observed. Benchmark testing on real municipal and ground water samples in continuous operation mode shows that ∼ 7500 and 5000 L water/g of membrane were treated well while maintaining WHO drinking water standards. The saturated membrane regenerated and successfully reused several times without losing purification performance. The present technique shows a great deal for addressing the worldwide problem of contaminated drinking water due to good selectivity, low fabrication cost, and excellent performance on real water.

Synthesis and Empirical Analysis of the Thermophysical Characteristics of GO-Ag Aqueous Hybrid Nanofluid Using Environmentally Friendly Reducing and Stabilizing Agents

The remarkable potential of the carbon allotrope graphene and its derivatives in developing hybrid nanofluids has sparked considerable interest among researchers. These carbon nanoparticles offer excellent opportunities to blend with various metal or metal oxide nanoparticle binders to improve their material properties. This study focuses on investigating the synthesis, characterization, and thermophysical properties of silver- (Ag-) infused GO aqueous hybrid nanofluids with various weight percentages (0.025, 0.05, and 0.1 wt.%) using environmentally friendly reducing and stabilizing agents. Characterization of the hybrid nanofluids was performed using XRD, SEM, EDX, a UV-visible spectrometer, a particle size analyzer, and FTIR techniques. The thermal conductivity and viscosity of the GO-Ag hybrid nanofluids were experimentally determined in the temperature range of 293 K–333 K. Notably, the results indicated that the nanofluids with a concentration of 0.1 wt.% exhibited the most significant enhancement in thermal conductivity, with improvements of 15.22% at 293 K and 31.19% at 333 K compared to the base fluid. A mathematical model was developed based on the thermal conductivity experimental results using the response surface methodology (RSM). Overall, the results suggest that the silver nanoparticles-decorated aqueous graphene oxide hybrid nanofluid has promising potential as an innovative heat transfer fluid in various heat transfer applications.

Exploring enhanced interfacial charge separation in ZnO/reduced graphene oxide hybrids on alkaline photoelectrochemical water splitting and photocatalytic pollutant degradation

Visible light-driven photocatalysis and photoelectrocatalysis have been intensively investigated for environmental remediation and green fuel generation. A highly efficient dual functional catalyst based on rGO decorated ZnO was synthesized by a hydrothermal method. The rGO incorporation facilitates the effective utilization of solar energy and improves the charge carrier separation and transportation efficiency. 0.5 wt% GO incorporated ZnO/rGO hybrid shows the highest photocatalytic activity towards pollutant degradation. Pure ZnO shows photocatalytic efficiency of 85 %, while ZnO/rGO shows 95 % degradation efficiency. The apparent rate constant of ZnO/rGO (67 × 10−3 min−1) showed 2.7 fold enhancement in comparison to bare ZnO (24 × 10−3 min−1). Consequently, ZnO/rGO shows highest hydrogen evolution activity by photoelectrocatalytic (PEC) water splitting in alkaline medium with a significantly lower overpotential of only 755 mV at 10 mA/cm2. The Tafel slope 101 mV/dec obtained for the ZnO/rGO hybrid is much lower than that of ZnO (149 mV/dec). This significant enhancement in photoelectrocatalytic activity of the hybrid can be attributed to the enhanced visible light absorption and reduced charge carrier recombination upon rGO incorporation. PL, TCSPC, and photocurrent response measurements deepens the investigation of the separation efficiency of photogenerated electron-hole pairs. The observations provide novel insights into the development of photocatalysts that possess dual functions for the water-solar energy nexus.

Sensitive electrochemical biosensor for bisphenol A based on laccase immobilized on polypyrrole‐3‐carboxylic/Sb2O5/reduced graphene oxide hybrid nanomaterial

AbstractAn electrochemical biosensor for the bisphenol A determination was constructed onto a glassy carbon electrode modified with a hybrid nanostructure based on polypyrrole‐3‐carboxylic acid/Sb2O5/reduced graphene oxide and laccase enzyme. The hybrid nanostructure was characterized by X‐ray photoelectron spectroscopy (XPS), HR‐TEM, SEM microscopy, and electrochemical techniques. The biosensor displayed excellent response for bisphenol A determinations by differential pulse voltammetry, showing a theoretical detection limit of 9.9 nmol L−1 in the linear range of 0.1–1.0 μmol L−1. The biosensor demonstrated excellent selectivity in the determinations of bisphenol A in tap water without significant interference from other species, such as 17β‐estradiol, Estriol, Progesterone, Catechol, Hydroquinone, Ascorbic acid, and Dopamine. The biosensor also has presented an excellent performance in bisphenol A determinations in water, with recovery tax ranging from 99.6 to 101 %. Therefore, it can be used satisfactorily to detect bisphenol A in real samples.

Enriched properties of polypyrrole-copper oxide-reduced graphene oxide (PPY-CuO-rGO) hybrid nanocomposite for organic light emitting diodes (OLEDs) as electron transport layer (ETL) material

Enriched properties of polypyrrole-copper oxide-reduced graphene oxide (PPY-CuO-rGO) hybrid nanocomposite for organic light emitting diodes (OLEDs) as electron transport layer (ETL) material

High thermal conductivity and flame-retardant epoxy-based composites with low filler content via hydrazine foaming of graphene oxide and boron nitride hybrid fillers

In this study, we developed a composite material for thermal conductivity by creating a hyperbolic boron nitride (BN) and graphene oxide (GO) structure with surface treatment using phosphorus-containing functional groups. The resulting composite, with a 4.04 vol % hybrid filler content, was impregnated with epoxy resin. The composite achieved a thermal conductivity of 0.95 W/mK and exhibited a significant thermal conductivity enhancement (TCE) when compared to the neat EP (377 %), demonstrating its potential for mitigating thermal accumulation in industrial applications. Additionally, the tensile strength of the composite significantly improved up to 45.3 MPa and had excellent flame-retardant properties. These results highlight the effectiveness of the hybrid filler approach in enhancing thermal and mechanical properties. The developed composite holds promise for various applications that require improved heat transfer and enhanced mechanical performance.

Enhancing out-of-plane thermal conductivity of polyimide-based composites via the construction of inter-external dual heat conduction network by binary fillers

Polyimide (PI) materials have found widespread utilization in advanced electronic systems. PIs with enhanced out-of-plane thermal conductivity (K⊥) are urgently required to address the rising need for heat dissipation. However, their production remains a formidable challenge due to the difficulty of constructing heat transmission channels along the thickness direction. This study introduces an innovative approach to enhance the K⊥ values of PI-based composites by utilizing binary fillers to construct an inter-external dual heat conduction network. To achieve this, we first prepared PI/reduced graphene oxide (rGO) hybrid microspheres via solution mixing and precipitation. The microspheres were then coated with boron nitride nanosheets (BNNS) by self-assembly to form a core-shell architecture. This assembly undergoes further refinement via cold-pressing and subsequent densification through hot-pressing, ultimately producing the (PI/rGO)@BNNS composites. This strategy improved K⊥ values significantly, with a 13-fold and 3-fold increase in the K⊥ value (3.98 W m−1 K−1) in comparison to pure PI (0.31 W m−1 K−1) and the random distribution composite (1.45 W m−1 K−1), respectively. The finite element analysis confirmed that the synergistic effect of rGO inside the PI phase and BNNS outside the PI phase greatly increased the heat transfer in PI-based composites. When utilized as a thermal interface material (TIM) for LED bulbs, the (PI/rGO)@BNNS composites exhibit an excellent heat dissipation capacity. Additionally, the prepared composites also maintain electrical insulation and present a reduced coefficient of thermal expansion. Overall, our work provides a simple and efficient technique for enhancing the out-of-plane thermal conductivity and maintain the electrical insulation of high-performance PI-based materials, which could have broad application potential in next-generation electronic devices.

Enhancing the Ultrafast Third-Order Nonlinear Optical Response by Charge Transfer in VSe2-Reduced Graphene Oxide Hybrid

Enhancing the Ultrafast Third-Order Nonlinear Optical Response by Charge Transfer in VSe₂-Reduced Graphene Oxide Hybrid

Photocatalytic Degradation Studies of Organic Dyes over Novel Cu/Ni Loaded Reduced Graphene Oxide Hybrid Nanocomposite: Adsorption, Kinetics and Thermodynamic Studies.

Nowadays, for environmental remediation, photocatalytic process involving graphene-based semiconductors is considered a very promising oxidation process for water treatment. In the present study, nanocomposite (Cu/Ni/rGO) has been synthesized by Dypsis lutescens leaf extract. Characterization of the sample was carried out by UV-visible spectroscopy, scanning electron microscopy (SEM), energy dispersive X-ray (EDX) analysis, Fourier transform infrared spectroscopy (FTIR), and X-ray diffraction (XRD). Different parameters like contact time, nanocatalyst amount, dye concentration, effect of temperature. and pH factor were optimized to examine the maximum removal efficiency for dyes rhodamine B and alizarine R with and without visible light source. In both cases, i.e., with or without light, maximum removal was observed at 20 mg of nanocatalyst for 5 ppm concentration of both dyes at 45 °C temperature and pH 10 for rhodamine B and pH 4 for alizarine R, respectively with a 20 min contact time. Maximum removal of dyes 93% rhodamine B and 91% alizarine R were observed under a tungsten lamp as compared to without a tungsten lamp, i.e., 78% of RhB and 75% of AR from mixture solution of these dyes. To assess the rate of reaction, spontaneity, and nature of reaction thermodynamics, kinetics and adsorption isotherms were studied. Thermodynamic values indicated that both dyes depicted endothermic and spontaneous degradation processes. Isotherm data fitted best to a Freundlich isotherm, while results of kinetic studies of both dyes followed the pseudo 2nd order kinetic equation. In the end, scavenging radical studies concluded that hydroxyl radicals were the main active specie involved in the photocatalytic degradation process, and regeneration experiments resulted that Cu/Ni/rGO nanocomposites were re-utilized for about four times.

Investigation on fatigue life of HAp and rGO hybrid coating on the PEEK artificial screws for dental implant

The mechanical behaviour of dental implants is crucial to their long-term endurance. Despite the demonstrated efficacy of dental implants, mechanical and biological concerns revealed in long-term follow-up studies continue to be a cause for concern. Screw loosening, which is usually caused by masticatory pressures when chewing, and peri-implantitis owing to microleakage are two of them, and if left untreated, they can lead to gradual loss of the supporting crestal bone. This study investigated the influence of hydroxyapatite (HAp) and reduced graphene oxide (rGO) hybrid coatings on the threads of a dental implant retention screw made of polyetheretherketone (PEEK). HAp with different concentrations of rGO (0.25, 0.5, 0.75, and 1%) coatings were investigated. The clamping force (CF) and coefficient of friction (COF) of the screw thread pair, as well as the single load fracture and dynamic fatigue life tests, were assessed to determine the integrity of the implant thread connection. The screw fracture mechanism and screw thread surface erosion morphology were also studied. The results revealed that C4 (HAp/rGO) coating might minimize COF, improve CF, and reduce fracture load. Furthermore, it demonstrated better anti-loosening properties under dynamic load. Most screw fractures happen on the screw's initial thread. The fracture end of a C3 combination coated screw was easily removed, but not that of a C4 combination coated screw.

Interfacial interaction of graphene oxide with montmorillonite in tailoring the structure and proton transport phenomena of alginate/PVA membrane for DMFC applications

AbstractPolymer electrolyte membrane that has high proton conductivity and low methanol permeability are necessary for direct methanol fuel cells (DMFCs). A sodium alginate (SA)/polyvinyl alcohol (PVA)/montmorillonite (MMT)/graphene oxide (GO) quaternary composite membrane was effectively developed in this study. The homogeneous distribution of MMT and GO nanosheets in the SA/PVA/MMT/GO composite membrane was exhibited by scanning electron microscopy (SEM). Intriguingly, it has been established that the SA/PVA membrane contains chemical crosslinks between MMT and GO, which significantly contribute to the rise in proton conductivity. The SA/PVA/MMT/GO hybrid membrane has minimum loss modulus of 47.91% and storage modulus of up to 2.689 × 109 Pa, which are 3.8 times greater than those of SA/PVA‐MMT membrane without GO. This value indicates the viscosity and elasticity of the produced membrane. The quaternary composite membrane also exhibits outstanding oxidative stability and methanol barrier characteristics. The methanol permeability of SA/PVA/MMT/GO films 0.524 × 10−9 cm2 s−1, with methanol absorption as low as 9.72%. The best membrane performs at a high‐power density (1.761 mW/cm2) of DMFC at a GO content of 1.3 wt% because it obtains the maximum selectivity value (7.0529 × 106 S scm−3). Future commercial membranes may be replaced by the innovative quaternary membrane created in this work, which has significant potential.