Graphene Oxide Composites Research Articles

Co-adsorption mechanism of organic pollutants on NiFe2O4/GO nanostructures: Experimental and molecular dynamics studies

The simultaneous removal of two or more pollutants from an aqueous medium requires a composite adsorbent that can provide sites specific to different adsorbates. But it is difficult to decipher the molecular-level adsorption mechanism under such circumstances. We combine experimental and classical molecular dynamics simulations to gain insight into this research problem. The present research investigates the simultaneous removal of ciprofloxacin (CIP) and methyl orange (MO) from an aqueous medium using a composite of graphene oxide (GO) and superparamagnetic NiFe2O4 nanoparticles. The adsorbent demonstrated economical and efficient magnetic recyclability. The co-adsorption isotherm data for CIP and MO best fitted the Extended Freundlich model, in agreement with the heterogeneous adsorption sites available on the composite. The experimental results were combined with classical molecular dynamics simulations to understand the predominant molecular-level adsorbate-adsorbent interactions. The latter revealed the two adsorbates adsorb to distinctly different adsorption sites on the NiFe2O4/GO composite.

Bifunctional additive: Lead dioxide nanoparticle-doped graphene oxide composites for the preparation and performance study of positive electrodes in lead-carbon batteries

Lead-carbon batteries (LCBs) possess the dual functions of supercapacitors and lead-acid batteries (LABs), which can meet the demand for renewable energy and in mild hybrid electric vehicles (HEVs) for energy storage and short-term high-rate charging and discharging. With the cycle of high-rate partial state-of-charge (HRPSoC), irreversible sulfation of the positive electrode becomes increasingly prominent and serious, resulting in low discharge capacity and short cycle life. In this study, to reduce the sulfation of the positive plate and improve the battery capacity and cycle life, a lead dioxide nanoparticle-doped graphene oxide (nano-PbO2/GO) composite material with dual functions of conducting and nucleating was prepared by a hydrothermal method as a positive electrode additive. The results show that the addition of nano-PbO2/GO promotes the formation of a three-dimensional short rod-like structure of PbO2 nanoparticles in a dendritic arrangement, accelerates the generation of new phases and inhibits the growth of bulk PbSO4. Moreover, the positive plate with nano-PbO2/GO exhibits good electrochemical activity to maintain the stability and reversibility of the electrode redox reaction. Finally, the initial discharge specific capacity of the LCBs with nano-PbO2/GO is increased to 153.85 mAh/g, and the HRPSoC cycle life is up to 15658 cycles at a 2 C discharge rate. Overall, the dual functions of nano-PbO2/GO greatly alleviate battery sulfation and provide a reference for improving the performance of LCBs by modifying the electrode structure.

Effective Removal of Hexavalent Chromium from Aqueous Solutions Using Quaternary Ammonium-Functionalized Magnetic Graphene Oxide Composites

Novel quaternary ammonium/magnetic graphene oxide composites (M-PAS-GO) that efficiently remove Cr(VI) ions were fabricated through the introduction of the (3-aminopropyl) triethoxysilane and Fe3O4 nanoparticles on the surface of GO, and then modified with n-butyl bromide. The fabricated M-PAS-GO was comprehensively characterized by SEM, TEM, EDX, XRD, Raman spectroscopy and FTIR, and the results manifest that the quaternary ammonium group was introduced onto the surface of GO. Under the reaction conditions of pH 3.20, temperature of 25 °C and M-PAS-GO dosage of 0.01 g/50 mL, 90% of 10 mg/L Cr(VI) ions were removed from the solution within 20 min. The kinetics study indicates that the adsorption process followed the pseudo-second-order model and was surface reaction-controlled. The thermodynamic parameters calculated from temperature-dependent adsorption isotherms suggest that the adsorption process was an exothermic and spontaneous process. The maximum adsorption capacities of Cr(VI) ions on M-PAS-GO composites calculated by the Langmuir model were 46.48 mg/g. Moreover, the reusability and stability of M-PAS-GO demonstrates its economic sustainability. This study suggests that M-PAS-GO is a potential candidate adsorbent for the separation of Cr(VI) from wastewater.

B2O3‐Nanoparticles‐Decorated N‐Rich Reduced Graphene Oxide Composites for the Enhanced Visible‐Light‐Assisted Photocatalytic Degradation of Ciprofloxacin

The occurrence of pharmaceutical pollutants in the environment is a mounting concern due to their detrimental effects on living organisms, including humans. Ciprofloxacin (CIP) is a regularly used antibiotic detected in wastewater and surface water. Therefore, developing effective, sustainable strategies for its elimination is paramount. Photocatalysis is an efficient approach that has been widely recommended for the removal of CIP from water. However, improved photocatalyst performance, stability, and activation in abundant visible light are essential for better photocatalyst systems. In this study, a novel boron‐oxide‐decorated nitrogen‐rich reduced graphene oxide (B2O3/N‐rGO) nanocomposite is prepared and characterized for its photocatalytic performance toward CIP degradation. The B2O3/N‐rGO nanocomposites are in situ synthesized via wet chemical route, and the morphology and structural properties of nanocomposites are extensively characterized. In the results, it is shown that the B2O3/N‐rGO nanocomposite demonstrated significantly enhanced photocatalytic performance (98%, 3 h) compared to N‐rGO and pure B2O3 toward the degradation of CIP under visible‐light irradiation. The enhanced photocatalytic activity is attributed to the synergistic benefit of B2O3 and N‐rGO, which improves light absorption, charge separation efficiency, adsorption sites, and delayed electron–hole recombination. In summary, the synthesized B2O3/N‐rGO nanocomposite photocatalyst can potentially be applied for various environmental remediation and energy‐related applications.

PH-responsive magnetic graphene oxide composite as an adsorbent with high affinity for rapid capture of nucleosides.

Anovel pH-responsive magnetic graphene oxide composite (MGO@PEI-BA) isproposed for the first time as an adsorbent for the rapid capture and detection of nucleosides (cytidine, uridine, guanosine, and adenosine). The morphology, structure, and magnetic properties of thecomposite were evaluated using various characterization techniques. The results indicated that the composite was successfully fabricated. A series of parameters that affect extraction and elution were optimized through one-factor-at-a-time and Box-Behnken design of response surface methodology (BBD-RSM). The unique layered structures and easily accessible active sites of the composite facilitated molecular transport, resulting in instantaneous equilibrium of nucleosides adsorption within 5 min. Based on this study, a magnetic dispersive micro-solid-phase extraction (MD-μ-SPE) method assisted by the MGO@PEI-BA was developed in combination with UHPLC-UV analysis for the determination of nucleosides in rat urine. Under the optimum conditions, a wide linear range (10-2000 ng mL-1), good linearity (r > 0.99), low detection limits (1-3 ng mL-1), low relative standard deviations (RSDs ≤ 3.9%), and satisfactory recoveries (82.7-96.3%) were achieved. These results demonstrate that the MGO@PEI-BA is an excellent adsorbent for extracting nucleosides from biological samples.

Fluorinated-Polyether-Grafted Graphene-Oxide Magnetic Composite Material for Oil–Water Separation

In this study, a new type of highly efficient and recyclable magnetic-fluorine-containing polyether composite demulsifier (Fe3O4@G-F) was synthesized by the solvothermal method to solve the demulsification problem of oil–water emulsion. Fe3O4@G-F was successfully prepared by grafting fluorinated polyether onto Fe3O4 and graphene-oxide composites. Fe3O4@G-F was characterized using scanning electron microscopy (SEM), Fourier-transform infrared spectroscopy (FTIR), transmission electron microscopy (TEM), and X-ray photoelectron spectroscopy (XPS). Taking the self-made crude-oil emulsion as the experimental object, the demulsification mechanism of the demulsifier and the influence of external factors, such as the temperature and pH value, on the demulsification performance of the demulsifier are discussed. The results show that the demulsification efficiency of the Fe3O4@G-F emulsion can reach 91.38% within 30 min at a demulsifier dosage of 750 mg/L, pH of 6, and a demulsification temperature of 60 °C. In neutral and acidic environments, the demulsification rate of the demulsifier is more than 90%. In addition, Fe3O4@G-F has been proven to have good magnetic effects. Under the action of an external magnetic field, Fe3O4@G-F can be recycled and reused in a two-phase system four times, and the demulsification efficiency is higher than 70%. This magnetic nanoparticle demulsifier has broad application prospects for various industrial and environmental processes in an energy-saving manner.

Bi0-Reduced Graphene Oxide Composites for the Enhanced Capture and Cold Immobilization of Off-Gas Radioactive Iodine.

Radioactive waste management is critical for maintaining the sustainability of nuclear fuel cycles. In this study, we propose a novel bismuth-based reduced graphene oxide (Bi0-rGO) composite for the immobilization of off-gas radioactive iodine. This material synthesized via a solvothermal route exhibited a low surface area (2.96 m2/g) combined with a maximum iodine sorption capacity of 1228 ± 25 mg/g at 200 °C. The iodine sorbent was mixed with Bi2O3 powder and distilled water to fabricate waste matrices, which were cold-sintered at 300 °C under a uniaxial pressure of 500 MPa for 20 min to achieve a relative density of ∼98% and Vickers hardness of 1.3 ± 0.1 GPa. The utilized methodology reduced the iodine leaching rate by approximately 3 orders of magnitude through the formation of a chemically durable iodine-bearing waste form (BiOI). This study demonstrates the high potential of Bi0-rGO as an innovative solution for the immobilization of radioactive waste at relatively low temperatures.

Tunable and efficient electromagnetic wave absorption of carbon material modulating magnetic ionic polymer-based composites

Developing the miniaturization and intellectualization of carbon-based chips and electronic devices is extremely desirable but remains hampered by electromagnetic interference. Magnetic ionic polymer (MIP) holds great promise for electromagnetic-absorbing material in the field of electromagnetic reliability of communication equipment due to its dielectric loss and magnetic loss are obviously higher than other commonly polymers. However, it remains a formidable challenge for MIP to achieve satisfactory absorption of electromagnetic wave (EMW). Herein, we achieved the excellent EMW absorbing performance of the poly[1-allyl-3-vinylimidazolium tetrachloroferrate]/carbon nanotube/reduced graphene oxide (P[AVIm][FeCl4]/CNT/rGO) composites when the only carbon materials loading of 10 wt%. Most strikingly, the effective absorption bandwidth (EAB) is as wide as 5.63 GHz, the lowest reflection loss can reach up to −51.05 dB with the absorber thickness of 2.2 mm. The enhancement in microwave absorption efficiency of P[AVIm][FeCl4]/CNT/rGO composites are arisen from the synergistic effects in its unique multicomponent heterostructure interface, which causes multiple reflections and strong conduction loss, further suitable impedance matching ratio and favorable attenuation ability. This work proposes a new perspective approach and fundamental absorption mechanisms to realize excellent performance EMW absorption.

Magnetic and ultrasonic integrated photocatalytic hydrogen evolution effects with Nanosize CoOCu2OZnO and TiO2 decorated on reduced graphene oxide

In this study, metal oxide composite (CoOCu2OZnO) and TiO2 on graphene oxide composite (CCZ−G−T) were synthesized to improve visible light-driven H2 evolution through the addition of a cation scavenger, ultrasonic effect, and magnetic field effect. The synthesized nanocomposites were characterized through structural, surface, and electrochemical analyses with band structure. The photocatalyst showed hydrogen production of 792 μmol·g−1 for 4 hours. Moreover, this CCZ−G−T photocatalyst exhibits relatively high photocatalytic activity at (530−810) μmol·g−1 when using a scavenger, 1,190 μmol·g−1 when using a magnetic field of 0.14 T, and 1,230 μmol·g−1 when using ultrasonic waves. The CCZ−G−T composite exhibited 630 μmol·g−1 under a magnetic field condition of 0.14 T for 1 hour, which was significantly higher than the hydrogen production rate of 510 μmol·g−1 under ultrasonic conditions. The current study provides new insights into the magnetic field effect on the hydrogen evolution reaction (HER) of graphene-based photocatalysts.

Fabrication of 1D Ni nanochains@Zn2+ doping polypyrrole/reduced graphene oxide composites for high-performance electromagnetic wave absorption

Nowadays, electromagnetic radiation significantly impacts the normal operation of electronic devices and poses risks to human health. To effectively address this problem, the development of composites that exhibit exceptional electrochemical wave absorption through the combination of different components holds great promise. In this study, we have successfully prepared 1D Ni nanochains@Zn2+ doping polypyrrole/reduced graphene oxide (Ni NCs@Z-P/RGO, denoted as R-x) composites using a combination of hydrothermal, solvothermal, in situ polymerization, and physical blending methods. Notably, the R-2 composite demonstrates a remarkable minimum reflection loss (RLmin) of −63.58 dB at 14.3 GHz, with a thickness of 1.61 mm. Furthermore, the R-2 composite exhibits an impressive effective absorption bandwidth (EAB) of 5.08 GHz (11.92 GHz-17 GHz) at a thickness of 1.67 mm. These outstanding performances can be attributed to the synergistic effect of the different components and a well-thought-out structural design. Moreover, to showcase the practical applicability of the material, we have conducted additional investigations on the reduction of the radar cross-sectional area (RCS). The results strongly demonstrate that the prepared composite material, when used as a coating, effectively reduces the RCS value by up to 26.6 dB m2 for R-2 at θ = 0°. The experimental methods and simulations presented in this study hold significant potential for application in wave absorption research and practical implementations. Additionally, the prepared Ni NCs@Z-P/RGO composites demonstrate feasibility as wave-absorbing materials for future utilization.

A Nanoscale Ternary Amide‐rGO Composite with Boosted Kinetics for Reversible H2 Storage

AbstractMetal amides are attractive candidates for hydrogen storage due to their high volumetric and gravimetric hydrogen densities. However, the sluggish kinetics and competing side reactions during hydrogen uptake and release limit their practical use. Here, a novel nanoconfined Li2Mg(NH)2@reduced graphene oxide (rGO) composite is presented, which is fabricated using a melt‐infiltration method with a minimum weight penalty of only 2 wt.%. The presence of rGO ensures close contact between the active phases, effectively preventing aggregation during cycling process. As a result, the reversible capacity of Li2Mg(NH)2@rGO reaches 4.42 wt.%, with no capacity degradation observed after multiple cycling. Theoretical calculations show that rGO catalyzes the hydrogen bond cleavage at the Mg‐amide/Li hydride interface, leading to local dehydrogenation hotspots and significantly improves kinetics of dehydrogenation compared to the bulk counterpart. This study provides a promising strategy for designing metal imide‐based composites to overcome the kinetic limitations and improve their reversible hydrogen storage performance.

The comparing on the adsorption/desorption of Pd(II) and Pt(IV) ions by using 4-chlorophenyl sulfoxide modified the reduced graphene oxide composite

The comparing on the adsorption/desorption of Pd(II) and Pt(IV) ions by using 4-chlorophenyl sulfoxide modified the reduced graphene oxide composite

Preparation of Biodegradable Reduced Graphene Oxide/Agar Composites by In Situ Reduction of Graphene Oxide

Plastics are ubiquitous in our daily life. However, the use of petrochemical-based plastic as packaging materials causes the depletion of non-renewable resources, thereby leading to an increase in oil prices and economic crises. Moreover, these petrochemical plastics raise the issue of environmental pollution due to their non-biodegradability. Owing to this, there is a need to develop an alternative biodegradable and eco-friendly packing material. Agar, which is extracted from seaweeds, is one of the abundantly available polymers. However, moderate tensile strength and thermal stability restrict its application. As a step forward, agar/reduced graphene oxide (RGO) composites were prepared by in situ reduction of GO in the polymer matrix. The tensile strength of the composite was found to increase by 55% at 2% RGO loading. The electrical conductivity and thermal properties of the composite were also improved. The presence of conductivity suggested that apart from packaging, agar/RGO composites can also have potential applications as capacitor plates creating a supercapacitor and as electric field-induced wound healing material.

Experimental Investigation of Mechanical Properties of Clay–Cement Slurry Containing Graphene Oxide

As a widely used material in underground engineering, clay–cement slurry grouting is known for its initial poor anti-seepage and filtration capacity, the low strength of the resulting stone body, and its tendency towards brittle failure. To explore efficient and environmentally friendly grouting materials, industrial-grade graphene oxide (GO) was incorporated into a clay–cement slurry to create a new type of slurry called a GO composite. These GO composites were then utilized to reinforce fractured formations. Uniaxial compression tests, shear strength tests, permeability tests, and electron microscopy scans were conducted to investigate the strength, permeability, and microscopic features of the GO composite-reinforced fractured formations. Furthermore, the optimization effect and application prospects of graphene oxide on clay–cement slurry materials were evaluated. The experimental results demonstrated that the modified slurry effectively improved the compressive strength (increased by 7.2% to 32.5%) and shear strength (increased by 28.6% to 105.3%) of consolidated fractured gravel. By conducting orthogonal experiments with range analysis, variance analysis, and multiple regression analysis, it was shown that there was a strong correlation between the consolidated body and three factors influencing the permeability coefficient. Among these factors, the OPC content had the most significant impact on the permeability coefficient, followed by the GO content. Graphene oxide was found to promote cement hydration reactions, guide the growth of hydration products on the surface of graphene oxide nanosheets, optimize the pore structure in grouting materials, and reduce microcracks between the slurry and the fractured gravel interface. Electron microscopy characterization and fractal analysis revealed that the addition of graphene oxide effectively reduced the degree of microdamage during the sample’s failure process. This ensured the integrity of the sample during the unstable failure process, enhanced the material’s toughness, and improved its ability to resist loads.

Tribological properties of an epoxy polymer containing a magnetically oriented graphene oxide/iron oxide nanoparticle composite

A composite of graphene oxide (GO) and oleate-protected iron oxide nanoparticles (IONPs) has been developed, synthesized, and characterized by SEM, TEM, AFM, and FTIR spectroscopy. The dispersion of GO/IONPs in an organic medium in the presence of an external magnetic field exhibits a magneto-optical effect that was used to obtain a composite material based on the NPEL-128 amino-cured epoxy resin. The viscosity of the composition was adjusted by adding n-butylglycidyl ether (BGE), the optimal composition was chosen with a BGE content of 30 wt%. The samples were obtained without nanoadditives, with the addition of GO, IONPs, and GO/IONPs particles, the latter were cured without applying a magnetic field, as well as parallel and perpendicular to the direction of the magnetic field. The obtained samples were tested for wear with the determination of the friction coefficient and wear rate, as well as the analysis of the wear profile. It has been established that samples with GO/IONP cured in a magnetic field were subjected to the greatest wear. Conclusions are drawn about the core role of the orientation of GO/IONPs flakes in a magnetic field in the mechanism of wear of polymer nanocomposite samples.

Cu3(hexaamino triphenylhexane)2/reduced graphene oxide composites with boosting electron-transfer properties for acetaminophen electrocatalytic degradation

Electron-transfer properties, as great contributors for electrocatalytic oxidation on the anode, are crucial to pollution degradation. The strong relationship between electron-transfer properties and active species (such as radicals) generation of anode catalysts suggests a new strategy for pollution-degradation efficiency improvement. In this study, a novel composite of Cu3(hexaamino triphenylhexane)2 [Cu3(HITP)2] and reduced graphene oxide (RGO) was synthesized to construct electron-transfer pathways between the two layers. Benefiting from the connection formed through RGO-O-N-Cu, the electron transfer from RGO to Cu3(HITP)2 was accelerated. The resettled charge distribution led the C atoms in the RGO layer, and the Cu and C atoms in Cu3(HITP)2 layer acted as the main surface active sites. O2•–, 1O2, and reactive chlorine were then triggered to boost the degradation of acetaminophen. The source of O2•– and 1O2 was more likely from surface oxygen groups rather than dissolved O2. Overall, this research provided a perspective proof of conductive Cu3(HITP)2/RGO composite construction with 2D/2D structure for electrocatalytic-oxidation improvement.

Conduction mechanism in hot-pressed Poly(vinylidene fluoride)/Graphene Oxide composites

Poly(vinylidene fluoride)/Graphene Oxide (PVDF/GO) composites were prepared by solvent casting and processed by hot pressing. Filler GO is synthesized by the improved Hummers method and purified by centrifuging. GO is characterized by XRD, FTIR, RAMAN, SEM, and TEM. XRD, FTIR, and DSC techniques were employed to characterize composites. AC conductivity data of PVDF and PVDF/GO composites with varying GO content were fitted with Jonscher’s power law at different temperatures, and the obtained DC conductivity was used to find the activation energy of the samples. The frequency exponent in power law is analyzed to identify the conduction mechanism in the composites. The frequency and temperature dependence of the exponent value and the nature of the frequency exponent with temperature confirm the overlapping large polaron tunneling as the responsible mechanism of conduction in PVDF/GO composites.

Enhanced Corrosion Resistance of Waterborne Epoxy Coatings by Polyaniline Nanorods and Nitrogen and Fluorine Dual-Doped Graphene Oxide Composites

Enhanced Corrosion Resistance of Waterborne Epoxy Coatings by Polyaniline Nanorods and Nitrogen and Fluorine Dual-Doped Graphene Oxide Composites

Electrochemical Monitoring of Sulfadiazine via La@CeO Incorporated with Reduced Graphene Oxide

In recent years, indiscriminate consumption and dumping of antibiotics have become destructive to human health and causes ecotoxicological pollution. Here, the irregular particle nanosized dendrite structure of lanthanum-doped cerium oxide (LCO) decorated with sheet-like reduced graphene oxide (RGO) composite was utilized to detect the sulfonamide-based drug sulfadiazine (SZ). LCO@RGO nanocomposite was prepared using the hydrothermal method, the synergistic effect between LCO and RGO facilitates electron transferability and conductivity which enhances the electrochemical properties toward the detection of SZ. The detection of SZ expressed a lower detection limit (0.005 µM) and linear range (0.01–265 µM) of the fabricated LCO@RGO/GCE electrode toward SZ, analyzed using the highly sensitive DPV technique. Also, DPV was utilized to determined shows good repeatability, reproducibility, and storage stability of fabricated LCO@RGO/GCE. Moreover, effective practicability was proven in human blood serum and river water samples with great recovery results. All the above probes the synthesized LCO@RGO’s thriving and outstanding electrocatalytic performance of this nanocomposite’s highly sensitive detection of SZ in real biological and environmental samples.

A sustainable route for production of graphene oxide-contained nanostructured carbons from rice husk waste and its application in wastewater treatment

Agricultural biomass, such as rice husk (RH), is a renewable source of bioenergy. However, a large amount of RH ash (RHA) is generated after the thermal conversion of RH. The main component of RHA is silica (>85 wt%). This study used recyclable RHA as a mesoporous SBA-15 template source. Next, ordered mesoporous carbon/ graphene oxide (RH-CMK-3/GO) composites were synthesized through the direct carbonization of GO, sucrose, and an SBA-15 template. Experimental data demonstrated that GO was successfully conjugated on the surface of CMK-3. The RH-CMK-3/GO exhibited a highly ordered mesostructure, which was not affected by the incorporation of GO. Compared with bare RH-CMK-3, the RH-CMK-3/GO had an enhanced surface area and pore volume. The composite exhibited a highest pore volume of 1.143 cm 3/g, a surface area of 1138 m2/g, and a pore diameter of 3.68 nm. The RH-CMK-3/GO revealed a higher ability for the adsorption of rhodamine B (RhB) than did the SBA-15, SBA-15/GO, and pure CMK-3 materials. The removal of RhB increased with increases in the composite dosage, solution pH and temperature, and carbonization temperature and time and a decrease in the initial RhB concentration. Moreover, the RH-CMK-3/GO exhibited a highest removal efficiency of 100%. The thermodynamics, kinetics, and isotherm adsorption data for the RH-CMK-3/GO composite exhibited satisfactory fitting for the endothermic, pseudo-second-order, and Langmuir models, respectively. Moreover, the composite exhibited good reusability. These results suggest that RHA can be effective for the fabrication of valuable mesoporous carbon nanocomposites and the elimination of organic contaminants from wastewater.