Graphene Oxide-based Composites Research Articles

Polyaniline and Graphene Oxide or Reduced Graphene Oxide-Based Composites for Environmental Remediation Application

Polyaniline and Graphene Oxide or Reduced Graphene Oxide-Based Composites for Environmental Remediation Application

Designing of Fe- ZIF67 derived Fe-Co/NC with its reduced graphene oxide-based composites for hydrogen and oxygen evolution reaction

This study focuses on the rational design and synthesis of catalysts for the hydrogen evolution reaction (HER) and oxygen evolution reaction (OER). A two-step method is employed, where the catalysts are first designed through hydrothermal synthesis and then subjected to pyrolysis at 400 °C under an argon environment. The performance of the designed electrocatalyst Fe-Co/NC, along with its 1, 3, 5, and 7 wt% rGO-based composites, is compared against commercial catalysts, 5 wt% Pt/C, and IrO2, for HER and OER. From all of the synthesized electrocatalysts, the 5 wt% rGO@Fe-Co/NC electrocatalyst exhibits exceptional electrochemical activity with less overpotential for both HER (−0.164 V) and OER (0.14 V) in the presence of alkaline media. Furthermore, this composite remained stable for 24 h without any degradation. The improved electrocatalytic activity of the 5 wt% rGO@Fe-Co/NC composite compared to Fe-Co/NC can be attributed to the presence of support materials like rGO and the availability of nanoporous carbon containing iron and cobalt. This successful combination of doping and interface engineering holds significant promise in the design of advanced electrocatalytic materials for water-splitting processes.

Surface-modified graphene oxide-based composites for advanced sequestration of basic blue 41 from aqueous solution

Advanced materials for the efficient treatment of textile wastewater need to be developed for the sustainable growth of the textile industry. In this study, graphene oxide (GO) was modified by the incorporation of natural clay (bentonite) and mixed metal oxide (copper-cobalt oxide) to produce GO-based binary and ternary composites. Two binary composites, GO/bentonite and GO/Cu–Co Ox (oxide), and one ternary composite, GO/bentonite/Cu–Co Ox, were characterized by Fourier transform-infrared spectroscopy (FTIR), scanning electron microscope (SEM), energy dispersive spectrometer (EDS) and Brunauer-Emmett-Teller (BET) analysis. The adsorption efficiency of these composites was evaluated against a cationic dye, Basic Blue 41 (BB41). The composites had several surface functional groups, and the ternary composite had tubular porous structures formed by the cross-linking of the bentonite and GO planes. The BET surface area of the ternary composite was 50% higher than that of the GO. The BB41 removals were 92, 89, 80, and 69% for GO/bentonite/Cu–Co oxide, GO/bentonite, GO and GO/Cu–Co oxide, respectively. The pseudo-2nd-order and intraparticle diffusion models best describe the kinetics results, indicating chemisorption and slow pore diffusion-controlled adsorption processes. The Langmuir isotherm-derived adsorption capacity of GO/bentonite/Cu–Co oxide was 351.1 mg/g, which was very close to the measured value. After five consecutive cycles, the ternary composite retained 90% BB41 removal efficiency compared to its 1st cycle. Electrostatic interaction and pore diffusion were predicted to be the controlling mechanisms for the adsorption of the BB41. The GO-based ternary composite can be a feasible and scalable adsorbent for BB41 in wastewater treatment.

Facile synthesis of novel Z-scheme GO-modified ternary composite as photocatalyst for enhanced degradation of bisphenol-A under sunlight

BackgroundPhotocatalytic degradation using sunlight as a light source has attracted increasing attention because of low operating cost, high degradation efficiency, and environmental friendliness. Metal oxide decorated graphene oxide-based composites as Z-scheme photocatalysts are highly efficient in degrading bisphenol-A (BPA), but such studies are scarce. MethodsThis work employed a facile and green synthesis route for Z-scheme GO-modified ternary composite (ZnO/GO/Mn2O3) photocatalyst. FTIR, FESEM, RAMAN spectra, EDX, BET, XRD, UV–Vis DRS, and PL spectra characterized the synthesized materials. Significant findingsThe results indicate that the catalyst's bandgap energy and surface area were 1.69 eV and 75.35 m2/g. The synthesized ZnO/GO/Mn2O3 composite degrade BPA under sunlight irradiation and completely degraded within 20 min reaction time, pH 7, and using 10 mg/100 mL catalyst dosage. Free radical capturing experiments established that the dominant reactive species for degradation were •O2− and h+ having 95.16 and 91.23% degradation efficiency. The kinetic study show that the pseudo-first-order best presents the kinetic model, and the rate constant (0.201 min−1) was 22.22, 14.28, and 4.08 times higher than Mn2O3, GO, and ZnO/GO, respectively. The enhanced catalytic activity occurred due to the development of an efficient Z-scheme heterojunction, which facilitates the separation of charge carriers, thereby increasing the number of reactive species in the solution. The recycling experiments showed only 10.85% degradation was reduced after five consecutive cycles. Finally, a plausible BPA degradation mechanism was proposed.

Enhanced electromagnetic wave absorption of nitrogen-doped reduced graphene oxide aerogels with LaFeO3 cluster modifications

Today, electromagnetic wave (EMW) absorbing materials with strong absorption capacity alone are hardly enough to meet the growing problem of EMW pollution. This work is the first designs and synthesizes LaFeO3-decorated nitrogen (N)-doped reduced graphene oxide aerogel (LFO/N-rGO) novel composites by a simple hydrothermal method. When the mass ratio of the LaFeO3 (LFO) nanoparticles: graphene oxide (GO): urea is 1:5:7.5, LFO/N-rGO achieves broadband absorption while possessing strong electromagnetic wave absorption capability. A strong reflection loss (RL) of −64.5 dB is obtained at 9.2 GHz. In addition, the maximum effective absorption bandwidth with a 2.83 mm thickness can reach up to 6.72 GHz. The EMW absorption mechanism analysis shows that the excellent microwave absorption capability is mainly attributed to the enhanced multiple reflections and multi-scattering, enhanced interfacial polarization process, proper conduction loss, and optimized impedance matching characteristics. Herein, this work proposes a new approach to improve the microwave absorption capability of N-doped reduced graphene oxide-based composites and provides a novel strategy to design EMW absorbing materials with wide effective absorption bandwidth and strong absorption capacity.

A comparative analysis of the electrochemical performance obtained for magnetic graphene oxide-based composites

Low dimensional carbon allotropes are the most used materials in composites. In addition, when magnetic nanostructures are assembled with carbon-based materials, a versatile material for building sensitive electrodes is achieved. Here, we propose a route to obtain magnetic composites based on both graphene oxide and reduced graphene oxide with permalloy nanowires. A comparative analysis of the electrochemical performance for such composites reveals that a relatively small amount of magnetic nanowires leads to an increased conductivity with respect to that of the pristine matrix, being such effect more pronounced for the graphene oxide-based composite. Therefore, the presence of permalloy nanostructures plays a determinant role in the conductive properties of graphene oxide-based materials, providing an attractive alternative for sensing purposes.

Photothermal oxidation of cyclohexane by graphene oxide-based composites with high selectivity to KA oil

Designing high-performance catalyst for the oxidation of cyclohexane (CyH) into value-added products like cyclohexanol and cyclohexanone (the mixture called KA oil) is of paramount significance in chemical industry. Herein, the catalytic activity of graphene oxide coupled with Ag and Fe3O4 nanopaticles composites (GO-Ag&Fe3O4 NPs) was investigated to understand the synergistic effect between Ag and Fe3O4 NPs in photothermal oxidation of CyH. The comparative experiments between thermal and photothermal catalysis indicated that: (a) Conversion efficiency was facilitated by temperature rise, but less than 50 % of selectivity to KA oil was obtained at high temperature (140 °C); (b) Higher selectivity and milder condition were achieved by photothermal catalysis comparing to that of the thermal catalysis; (c) Ag NPs played more important role in photocatalysis, while thermocatalysis was intensified by Fe3O4 NPs. Using 1.5 MPa of dry air as oxidant, 6.6 % of CyH conversion with over 98 % of selectivity was gained by GO-Ag&Fe3O4 NPs. Additionally, no obvious decline in catalytic efficiency was observed after 5 cycles. The concept of photothermal cooperation for CyH oxidation over GO-Ag&Fe3O4 NPs may provide a new approach for the partial oxidation of saturated CH and the design of high-performance catalysts.

Retraction: Mechanistic insights into the decontamination of Th(iv) on graphene oxide-based composites by EXAFS and modeling techniques

Retraction: Mechanistic insights into the decontamination of Th(<scp>iv</scp>) on graphene oxide-based composites by EXAFS and modeling techniques

Adsorption of carcinogenic dye Congo red onto prepared graphene oxide-based composites

Adsorption of carcinogenic dye Congo red onto prepared graphene oxide-based composites

Solar photo-degradation of aniline with rGO/TiO2 composites and persulfate

The solar photodegradation of aniline using reduced graphene oxide-based composites (rGO/TiO2) and different electron acceptors such as H2O2 and persulfate (PS) has been studied. To this end, an innovative self-sufficient drum reactor (operating with solar irradiation and artificial UV light) has been employed. The role of radicals and the new graphene morphology is evaluated. Finally, changes in the degradation/mineralization mechanism are explained according to intermediates evolution (obtained from mass spectroscopy).In the Solar/rGO/TiO2/H2O2 system, hydroxyl radicals react with the reduced graphene oxide (rGO) producing oxidized rGO (OrGO). The process creates new pores increasing surface area favouring adsorption. Also, other radicals such as superoxide or singlet oxygen are also formed, affecting the degradation mechanism. The hole reacts with adsorbed aniline to form the aniline-radical-cation. Nitrosobenzene is then formed with the active participation of superoxide radical anion, finally yielding azobenzene. It was found that the addition of 2.5% wt of rGO increases mineralization from 0 to 14% during the solar stage after 120 min, reaching 82.5% when lamps are switched on after 240 min.On the other hand, activation of PS with UV-C light is a very efficient process, since aniline is wholly degraded in 10–20 min depending on PS initial concentration, reaching a high mineralization degree close to 90% in 120 min. During this process, degradation occurs in a very different route, via the formation of phenol. In the first stage (t < 25 min), sulfate radical is the primary oxidant involved to yield benzoquinone. In a second step (t > 25 min), hydroxyl radicals play the leading role to reach C2-C6 organic acids.

Graphene and Graphene Oxide-Based Composites for Removal of Organic Pollutants: A Review

Graphene, graphene oxide (GO), and their composites have been prominently utilized for wastewater purification because of their adsorption, oxidation, and catalytic properties. Graphene and GO and its composites naturally have significant pore volume, high conductivity, rich surface chemistry, and an exceptionally large aspect ratio which make it favorable for adsorption and catalysis of organic pollutants from wastewater. The sheet-like, resonating, polyaromatic π-system of graphene subsidiaries play a significant role in π–π interactions, hydrogen bonding, and/or electrostatic interactions with organic pollutants that include dyes, pharmaceutical waste, and agricultural and industrial effluents whose base structure consists of notably reactive unsaturated aromatic rings and oxygen-rich functional groups. The adsorption capacities of pollutants have been widely researched and catalogued by considering the adsorption isotherm (Langmuir, Freundlich, Temkin, DR model) they fit, the kinetic models (pseudo-fi...

Development of Highly Water Stable Graphene Oxide-Based Composites for the Removal of Pharmaceuticals and Personal Care Products

In the present study, sorption of pharmaceuticals ((acetaminophen (ACP), carbamazepine (CBZ)) and personal care products (bisphenol A (BPA), caffeine (CAFF), triclosan (TCS)) using a graphene oxide (GO)-based composite adsorbent was extensively studied. Structural characterization indicated the incorporation of activated carbon and chitosan onto the GO. For both classes of pollutants, the adsorption kinetics followed a pseudo-second-order kinetic model. On the other hand, the Langmuir isotherm showed a better fit compared to the Freundlich isotherm. Maximum adsorption capacities of ACP, CBZ, BPA, CAFF, and TCS were found to be 13.7, 11.2, 13.2, 14.8, and 14.5 mg/g, respectively. Desorption of ACP, BPA, and CAFF was significantly higher in a polar solvent (70%–80%), whereas CBZ and TCS were able to desorb (60%) in a nonpolar solvent. DFT calculations indicated that the adsorption mechanism is majorly accompanied by size-related diffusion and also a minor contribution by synergetic combination of hydrophobi...

Adsorption of Ammonium by Graphene Oxide-Based Composites Prepared by UV Irradiation and Using as Slow-Release Fertilizer

A novel sodium alginate-grafted poly(acrylic acid)/graphene oxide (NaAlg-g-PAA/GO) composite hydrogel was prepared via ultraviolet irradiation, and characterized by infrared spectroscopy spectrometer. X-ray diffraction, X-ray photoelectron spectroscopy and scanning electron microscopy. It was employed to adsorb NH4+ from aqueous solution and used as slow-release nitrogen fertilizers (SNFs). Result indicated that the adsorption process for NH4+ reached equilibrium within 50 min, with the adsorption capacity of 6.6 mmol g−1 even if 30 wt% GO was incorporated. The results of adsorption kinetic and isotherm were well described by the pseudo-second-order and Freundlich model. The thermodynamics analysis showed the adsorption process was spontaneous. The study indicated excellent water-holding ratio of soil with 2 wt% SNFs was 81.2%, and nitrogen release was up to 55.1% within 40 days in soil. Overall, NaAlg-g-PAA/GO could be considered as an efficient adsorbent for the recovery of nitrogen with the agronomic reuse as a fertilizer.

Arousing effective attenuation mechanism of reduced graphene oxide-based composites for lightweight and high efficiency microwave absorption

To construct effective electromagnetic parameters of reduced graphene oxide (RGO)-based composites for lightweight and high efficiency microwave absorption, Ni/RGO composites were prepared via a facile in-situ hydrothermal process. Due to the strong high-frequency polarization effect related to the large surface contact area of the obtained Ni/RGO hybrids, the composites presented strong electromagnetic wave attenuation ability even when the filler content is only 1.6 wt. %. This work might deepen the understanding of the effective dielectric loss mechanism and impedance matching and provide an effective strategy for the practical application of RGO as a lightweight and high-performance microwave absorption material.

Rational design of sulfonated poly(ether ether ketone) grafted graphene oxide-based composites for proton exchange membranes with enhanced performance

Sulfonated graphene oxide (SGO) was synthesized by direct esterification reaction between graphene oxide (GO) and hydroxylated sulfonated poly(ether ether ketone) (SPEEK-OH) and then incorporated into sulfonated polyarylene ether nitrile (SPEN) to explore the effect of varying loading on performances of proton exchange membranes. It was found that SGO are uniformly dispersed and form perpendicular packing structure in matrix, triggering the formation of continuous and long-range proton transfer channels and effectively improving proton conductivity. Meanwhile, the water uptake, swelling ratio and methanol permeation are lowered to the corresponding composite PEM compared to pristine SPEN membrane. All of these are attributed to the formation of strong interfacial interaction between SPEN and SGO. As a result, the composite membranes possesses higher selectivity than pristine SPEN. Specially, the composite membrane contained 2 wt% SGO show the lowest swelling ratio at high temperature (just 13.77% at 80 °C) and the highest proton conductivity of 0.183 S·cm−1 at 80 °C. Our investigation indicates the great potential of SGO in fabricating composite PEMs and also provides a new approach for the development of PEMs.

Reduced graphene oxide-supported Ag-loaded Fe-doped TiO2 for the degradation mechanism of methylene blue and its electrochemical properties.

Graphene oxide-based composites have been developed as cheap and effective photocatalysts for dye degradation and water splitting applications. Herein, we report reduced graphene oxide (rGO)/Ag/Fe-doped TiO2 that has been successfully prepared using a simple process. The resulting composites were characterized by a wide range of physicochemical techniques. The photocatalytic activities of the composite materials were studied under visible light supplied by a 35 W Xe arc lamp. The rGO/Ag/Fe-doped TiO2 composite demonstrated excellent degradation of methylene blue (MB) in 150 min and 4-nitrophenol (4-NP) in 210 min under visible light irradiation, and trapping experiments were carried out to explain the mechanism of photocatalytic activity. Moreover, electrochemical studies were carried out to demonstrate the oxygen evolution reaction (OER) activity on rGO/Ag/Fe-doped TiO2 in 1 M of H2SO4 electrolyte, with a scan rate of 50 mV s−1. The reductions in overpotential are due to the d-orbital splitting in Fe-doped TiO2 and rGO as an electron collector and transporter.

Retracted Article: Mechanistic insights into the decontamination of Th(iv) on graphene oxide-based composites by EXAFS and modeling techniques

The sorption mechanism of Th(iv) on amidoxime/graphene oxide composites was investigated by extended X-ray absorption fine structure (EXAFS) spectra and surface complexation modeling.

A general strategy for the synthesis of reduced graphene oxide-based composites

Well-exfoliated graphene oxide sheets were initially fabricated through a modified pressurized oxidation method with powdered flake graphite as raw material. A variety of inorganic-reduced graphene oxide composites have been then successfully synthesized through a general solvothermal strategy with the graphene oxide sheets as supports, ethanol as solvent, and metal salts as precursors. After the solvothermal reactions, Ni(OH)2 nanoparticles, Fe2O3 nanorods, W18O49 nanowires, ZnO nanoparticles, and Ag nanoparticles were in situ grown on the surfaces of the graphene oxide sheets, accompanied by effective reduction of graphene oxide to reduced graphene oxide. The as-prepared products have been systematically characterized by electron microscopy, X-ray diffraction, X-ray photoelectron spectrometry, and Raman spectroscopy. The present work opens up a versatile route for preparing the reduced graphene oxide-based composites.

Fabrication and characterization of graphene oxide-reinforced poly(vinyl alcohol)-based hybrid composites by the sol–gel method

Functionalized graphene oxide-reinforced poly(vinyl alcohol) hybrid composites were prepared by using the sol–gel method. This method not only provided a “green” strategy for fabricating the graphene oxide-based composites, but also realized the covalent functionalization of graphene oxide nanosheets with polymer matrix. The morphology, thermal, fire resistance and mechanical properties of the f-GNS/poly(vinyl alcohol) hybrid composites were systematically studied. The transmission electron microscopy analyses demonstrated that f-GNS was homogeneously dispersed in the poly(vinyl alcohol) matrix. Combining with a series of analyses and characterizations, it was observed that the functionalization of graphene oxide with conjugated organosilanes was favorable for improving mechanical, thermal properties and flame retardance of the composites, which was mainly attributed to the homogeneous dispersion of functionalized graphene oxide in the polymer matrix and strong interfacial interactions between the two components.