3D hierarchical network ultralight RGOF/MoS2 samples: design, production and their extraordinary comprehensive microwave absorption properties.
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Using previous models and theories to ...construct and develop high-efficient microwave absorbers (MAs) should be a strategic and effective ways to optimize the electromagnetic wave attenuation. Herein, the ultralow density and flexible graphene oxide foam (GOF) and reduced graphene oxide foam (RGOF)/MoS2 nanosheets were designed and fabricated by the method of chemical vapor deposition and hydrothermal reaction. The obtained GOF and RGOF/MoS2 samples exhibited very excellent microwave absorption properties while their densities were merely 0.0082 and 0.0084 g•cm−3, respectively. More importantly, benefiting from the excellent synergistic effect between RGOF and MoS2, the designed RGOF/MoS2 well inherited the combined advantages of GOF and MoS2 in terms of strong absorption abilities, broad absorption bandwidth and thin matching thicknesses. The values of minimum reflection loss and effective frequency bandwidth for RGOF/MoS2 sample could reach up to −62.92 dB with the matching thickness of 2.27 mm and 4.48 GHz with the matching thickness of 2.12 mm, which were very desirable for high-performance MAs. Moreover, the obtained results indicated that the microwave absorption properties of RGOF/MoS2 sample could be further optimized by regulating the MoS2 content. Therefore, a new and effective strategy was proposed to develop high efficiency MAs with ultra-lightweight, wide-band, thin thickness and strong absorption capabilities.
This paper reports an electroanalytical sensor developed based on reduced graphene oxide/FeNi3 (FeNi3/rGO)-ionic liquid (n-hexyl-3-methylimidazolium hexafluoro phosphate (HMPF6) carbon paste ...electrode (CPE) for determining the antioxidant additive tertbutylhydroquinone (TBHQ) in the presence of folic acid. The FeNi3/rGO synthesized by hydrothermal strategy and characterized by X-ray diffraction (XRD) and FESEM methods. The electrochemical response were found to be linearly symmetrical to TBHQ and folic acid concentrations in the range from 0.05 to 900 μM and 0.6–1100 μM with detection limits of 10.0 nM and 0.1 μM, respectively. The FeNi3/rGO/HMPF6/CPE showed high-quality for determination of TBHQ in the presence of folic acid in the real samples with the separation potential ∼600 mV.
The presence study describe fabrication of novel electrochemical sensor based one carbon paste electrode modified with reduced graphene oxide/FeNi3-ionic liquid nanocomposite as sensor for simultaneous determination of tert-butylhydroquinone and folic acid. Display omitted
•Reduced graphene oxide/FeNi3-ionic liquid as novel electro-catalysts.•The first electrochemical sensor for simultaneous determination of tert-butylhydroquinone and folic acid in food samples.•Nano-molar determination of tert-butylhydroquinone in food samples.
Spillage of effluents containing high concentration levels of pesticides into water has been considered as one of the serious environmental problems. In this study Fe3O4/reduced graphene oxide (rGO) ...nanocomposite has been efficiently utilized for the adsorption of five harmful pesticides namely ametryn, prometryn, simazine, simeton and atrazine in an aqueous medium. Electrostatic interaction between the pesticides and Fe3O4/rGO nanocomposite was analyzed by the zeta potential analysis, which is strongly related to the adsorption capacity of the adsorbent. The kinetics parameters of adsorption followed the pseudo second-order linear model. The adsorption isotherm studies show that, the maximum adsorption capacity of 54.8 mg g−1 is achieved at pH 5 and it was enhanced in the presence of different ions (Mg2+, Ca2+, Na+ and SO42) and maximum (63.7 mg g−1) for ametryn adsorption was found in seawater medium. Thermodynamic parameter shows that, the adsorption process is physisorption and spontaneity in nature. The mechanism of the adsorption process was established by the DRIFT spectroscopy analysis. Efficient adsorption (93.61%) of pesticides was observed due to electrostatic, hydrophobic and π–π interactions of composite towards the heterocyclic conjugation of pesticide molecules. Further, Fe3O4/rGO nanocomposite was easily and rapidly separated from an aqueous medium using the external magnet for reuse and 88.66% adsorption efficiency was observed up to seven cycles.
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•A feasible and eco-friendly route for the removal of five triazine pesticides.•Magnetic Fe3O4/rGO shows efficient triazine pesticides removal property.•Specific ion effect plays an important role in pesticide adsorption onto Fe3O4/rGO.•The reusability and magnetic reparability of Fe3O4/rGO is added advantage.
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•A novel enzyme-free glucose sensor was fabricated by first using Ni(OH)2@PEDOT-rGO as electrode material.•Ni(OH)2@PEDOT-rGO was synthesized by a facile and easy-to-control ...electrodeposition method.•The sensor exhibited ultrafast response time, wide linear range, low detection limit.•It exhibited superb specificity, good stability and successfully for real sample analysis.
The novel nanocomposite of Ni(OH)2 nanoparticles over reduced graphene oxide and poly (3,4-ethylenedioxythiophene) hybrid film (Ni(OH)2@PEDOT-rGO) have been successfully fabricated via a facile, scalable and easy-to-control electrodeposition method. The characterization results of scanning electron microscope (SEM) and electrochemical techniques show that Ni(OH)2 nanoparticles with an average particle size about 10nm are uniformly deposited on PEDOT-rGO hybrid film with rough surface and reveal outstanding performance for detecting glucose. The enzyme-free glucose sensor exhibits an ultrafast response time (<1s), a wide linear range (0.002–7.1mM), a low detection limit (0.6μM) and a high sensitivity (346μAmM−1cm−2). Moreover, the sensor also displays superb selectivity, excellent reproducibility and good stability. The outstanding properties of the sensor may be attributed to the synergistic effect of Ni(OH)2 nanoparticles possessing high electro-catalysis activity and PEDOT-rGO having well conductivity. More importantly, the sensor was successfully used to determine glucose in the real samples. In addition, the mechanism of electrodeposited PEDOT-rGO and glucose oxidase was investigated.
•Preparation of a magnetic, superhydrophobic/superoleophilic polyurethane sponge.•High sorption capacity for oils and solvents in the 39.8–131.4 g/g range.•Excellent reusability even after 10 ...sorption–desorption repeated cycles.•Effective removal of oil droplets from surfactant-free and stabilized emulsions.•Improved flame-retardant properties.
Cost-effective and efficient sorbents with emulsion-breaking capability, especially surfactant-stabilized emulsions, are required to remediate oil spills from water. Herein, in situ growth of magnetic Mn0.01Co0.90Fe3O4 (MCFO) nanoparticles (NPs) on reduced graphene oxide (RGO) was performed to prepare MCFO/RGO nanocomposite via a simple solvothermal method. The nanocomposite was coated onto a polyurethane (PU) sponge to fabricate a novel magnetic, superhydrophobic/superoleophilic and flame-retardant material. The prepared magnetic MCFO/RGO/PU was superhydrophobic with a contact angle of 165 ± 1°. Compared with neat PU, the MCFO/RGO/PU sponge could be driven by a magnet for oil collection in water. More importantly, the MCFO/RGO/PU sponge could effectively collect oil droplets from surfactant-free and stabilized toluene/water emulsions. In addition, the fabricated sponge exhibited excellent performance for oils and organic solvents sorption, achieving up to 131 times of its own weight and retaining its ability even after 10 sorption cycles. Interestingly, the thermal stability and fire retardancy of the prepared PU sponge were improved with respect to neat PU.
In this study, we suggested first analytical sensor and especially electrochemical sensor for simultaneous determination of Cholesterol, ascorbic acid and uric acid.
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In this article, ...we report the simultaneous determination cholesterol (CL), ascorbic (AA) acid and uric acid (UA) at a carbon paste electrode (CPE) modified with copper oxide decorated reduced graphene (CuO-rGR), with 1-methyl-3-octylimidazolium tetrafluoroborate (1M3OIDTFB) as a binder. The electrode, CuO-rGR/1M3OIDTFB/CPE, showed remarkable sensitivities towards the determination of the analytes, and well defined and clearly separated oxidation peaks were obtained during their simultaneous analysis in a buffer solution at pH 7.4. The differences observed between their peaks potentials are as follows: 430 mV (between CL and AA), 270 mV (between AA and UA) and 700 mV (between CL and UA). The morphologies and structure properties of the CuO-rGR were investigated by FESEMD and EDAX methods. The CuO-rGR/1M3OIDTFB/CPE displayed linear response in the concentration ranges 0.04–300.0 μM, 0.04–240.0 μM and 0.4–400.0 μM for CL, AA and UA with the detection limits 9.0 nM, 9.0 nM and 0.08 μM, respectively. The CuO-rGR/1M3OIDTFB/CPE displayed high performance for the determination of CL, AA and UA in real samples.
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•Facile, green, and cost-effective nanocomposite adsorbents with tunable wettability.•In-situ reduction of GO using a green reducing agent in the presence of alginate.•Significant ...improvement of mechanical properties by in-situ reduction of GO.•Selective removal of hydrophobic contaminants in a complex matrix of DCF and TC.•747% and 660% increase in adsorption capacity for DCF and TC with only 3.5 wt% rGO.
Long-term exposure to pharmaceuticals, such as diclofenac (DCF) and tetracycline (TC), poses various risks to human health, including antibiotic resistance and endocrine disruption. In this work, we investigated the removal of DCF and TC from water and probed the removal performance of contaminants in a complex matrix consisting of DCF and TC mixtures using alginate (AL)-based nanocomposite beads with tunable wettability. We improved the selectivity of the beads towards hydrophobic contaminants by reducing graphene oxide (GO) to rGO in the presence of AL using a mild and green reducing agent (Vitamin C). Thein-situchemical reduction of GO in AL matrix resulted in amphiphilic rGO-containing beads,as confirmed by several characterization techniques.Thein-situreduction, apart from restoring the sp2hybridized carbon, greatly improved the mechanical properties and stability of the nanocomposite, ensuring reusability beyond 10 adsorption/desorption cycles.Compared to neat AL beads, the addition of only 3.5% rGO (AL:3.5rGO) improved the beads adsorption capacity for TC and DCF by 660% and 747%, respectively. The beads exhibited remarkable performance in the simultaneous removal of TC and DCF from contaminant mixtures. The superior performance of AL:3.5rGO beads is attributed to the enhanced π-π interactions between the aromatic rings of the contaminants and the sp2domains of rGO-containing adsorbents.
In this study, a multi-component catalyst, β-cyclodextrin (β-CD) and reduced graphene oxide (rGO) co-modified Fe3O4, was fabricated via one-pot solvothermal method and used as a synergistic catalyzer ...for Bisphenol A (BPA) removal. The study found that catalytic reactions of BPA followed the pseudo-first-order kinetics model, and the correlation rate constants (kobs) were calculated. Compared with Fe3O4@β-CD (0.02173 min−1), Fe3O4/rGO (0.09735 min−1) and Fe3O4 (0.01666 min−1), the composite (0.15733 min−1) exhibited stronger catalytic ability to remove BPA from aqueous solution under the same conditions, which were attributed to the synergistic enhancement effect among the components. The introduction of rGO in the composites was beneficial to the generation of •OH, and the role of β-CD might enhance the utilization of •OH. A possible three-element catalytic schematic diagram was described. The effects of pH, dosage of the catalyst, initial H2O2 and NH2OH concentrations on the removal efficiency were further investigated. The removal of BPA and TOC retained 78.2 ± 2.4% and 52.9 ± 2.5% after five cycles, indicating its excellent stability and reusability. Furthermore, a probable reaction pathway of BPA removal was suggested by analyzing the intermediate products. All results indicated that the composite had high and stable catalytic performance, which made it have potential application on the industrial treatment of wastewater.
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•Fe3O4@β-CD/rGO composite were firstly synthesized by One-pot solvothermal method.•Fe3O4@β-CD/rGO with kobs of 0.15733 min−1 for BPA exhibited strong catalytic ability.•The synergistic effect of composite catalyst in degradation of BPA was confirmed.•The catalysts showed excellent activity and reusability (about 80% after 5 cycles).
These findings provide further insights into the assessment of multi-component catalyst for endocrine disruptors elimination.
NCO/N, S-rGO is successfully synthesized for multifunctional applications, and the mechanisms of HMIs detection and HER are further explained.
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•NiCo2O4 decorated N, S codoped reduced ...graphene oxides are synthesized.•The synergetic effect, oxygen vacancies and hybridization of NCO/N, S-rGO improve its excellent electrocatalytic performance.•NCO/N, S-rGO has multifunctional applications for the electrochemical detection of HMIs and HER activity.
It is anenormous challenge to explore multifunctional electrocatalysts for simultaneous detection of Cd(II), Cu(II), Hg(II) and hydrogen evolution reaction (HER). In this work, NiCo2O4 decoratedN,Sco-doped reduced grapheneoxide composites (NCO/N, S-rGO) are synthesized via hydrothermal followed calcination process. The synergetic effect, oxygen vacancies and hybridization of NCO/N, S-rGO improve its excellent electrocatalytic performance for simultaneous and individual detection of Cd(II), Cu(II), Hg(II) and HER activity. When NCO/N, S-rGO is acted as heavy metal ions (HMIs) electrochemical sensors, it exhibits the high sensitivity and low detection limit for Cd(II) with 2.38 μA μM−1 and 123 nM, Cu(II) with 10.90 μA μM−1 and 14.4 nM, as well as Hg(II) with 5.41 μA μM−1 and 67 nM. NCO/N, S-rGO has outstanding stability and anti-interference performance and has been successfully implemented in the actual water environment. Furthermore, NCO/N, S-rGO also exhibits HER activity with overpotential and Tafel slope of 107 mV and 71.35 mV dec-1, respectively. The electrochemical detection and HER activity mechanism of NCO/N, S-rGO are further investigated and demonstrated that the synergetic effect of NCO/N, S-rGO can improve its electronic microstructure and promote electrocatalytic performance. This work not only provides a simple method for the preparation of multifunctional electrocatalysts, but also enhances the comprehension of HMIs detection and HER mechanism.
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•NRGO/Ni0.5Zn0.5Fe2O4 composite was fabricated by a facile two-step strategy.•Well-designed entanglement structure was clearly observed in the binary composite.•Complexing of NRGO ...notably enhanced the microwave absorption of Ni0.5Zn0.5Fe2O4.•The relationship between filler loading and refection loss was carefully clarified.•Strong absorption, broad bandwidth and thin thickness were simultaneously achieved.
Nowadays, developing high-performance microwave absorbers with thin thickness, strong absorbing, broad bandwidth and low filler loading is of great importance for solving the problem of electromagnetic pollution. Herein, nitrogen-doped reduced graphene oxide/nickel-zinc ferrite (NRGO/Ni0.5Zn0.5Fe2O4) composite was synthesized using graphene oxide (GO) as a template by a facile two-step strategy. Results of morphology observations revealed that well-designed entanglement structure consisting of Ni0.5Zn0.5Fe2O4 microspheres and crumpled NRGO was clearly observed in the as-prepared NRGO/Ni0.5Zn0.5Fe2O4 composite. Moreover, the effects of complexing of NRGO and filler loadings on the microwave absorption properties of NRGO/Ni0.5Zn0.5Fe2O4 composite were carefully investigated. It was found that the complexing of NRGO notably enhanced the microwave absorption properties of Ni0.5Zn0.5Fe2O4 microspheres. Significantly, the obtained NRGO/Ni0.5Zn0.5Fe2O4 composite demonstrated the optimal minimum reflection loss of −63.2 dB with a matching thickness of 2.91 mm in the X-band and effective absorption bandwidth of 5.4 GHz (12.0–17.4 GHz) almost covering the whole Ku-band with a thin thickness of merely 2.0 mm. Furthermore, the relationship between filler loading and refection loss was carefully clarified. Besides, the underlying microwave absorption mechanisms of as-prepared composite were proposed. It was believed that our results could shed light on the design and fabrication of graphene-based magnetic composites as high-efficient microwave absorbers.
