GO Surface Research Articles

Vertical carbon skeleton introduced three-dimensional MnO2 nanostructured composite electrodes for high-performance asymmetric supercapacitors

We successfully fabricate a hierarchical three-dimensional (3D) nanocomposite rGO/C/MnO2 composed of 2D/1D rGO/C and MnO2 nanosheets. The vertical porous carbon decorated rGO is obtained by growing covalent organic frameworks (COFs) arrays on the surface of GO with further calcination. After the introduction of the special rGO/C porous substrate, the rGO/C/MnO2 nanocomposite shows the more stable nanostructure, the larger specific surface area (~129.79 m2 g−1), and the better electrical conductivity. Benefiting from these, the rGO/C/MnO2 electrode possesses high specific capacitance (215.2 F g−1 at 0.5 mA cm−2 (~0.15 A g−1)), good rate capability and long cycling stability (72% capacitance retention after 2500 cycles). Solid-state asymmetric supercapacitors are assembled with rGO/C/MnO2 as the positive electrode material, activated carbon (AC) as the negative electrode material, and polyvinyl alcohol (PVA)/LiCl as the gel electrolyte. The device can provide a high power density of 3.6 kW kg−1 at a current density of 20 mA cm−2 (~3.2 A g−1) and a high energy density of 21.2 W h kg−1 at a current density of 1.0 mA cm−2 (~0.16 A g−1). Furthermore, two rGO/C/MnO2//AC asymmetric supercapacitors in series power a commercial LED more than 40 s.

Synthesis and photocatalitic activities of NiFe<sub>2</sub>O<sub>4</sub>/nitrogen-doped graphene oxide composite

In this work, the NiFe2O4/N-doped GO composites were successfully synthesized by the hydrothermal method. The structure, chemical compositions, the presence of functional groups, surface morphology, and magnetic properties of the obtained composites were investigated by X-ray Diffraction (XRD), Energy Dispersive X-ray Spectroscopy (EDX), Fourier Transform Infrared Spectroscopy (FT-IR), Scanning Electron Microscopy (SEM), Transmission Electron Microscopy (TEM) and Vibrating Sample Magnetometer (VSM). The experimental results show that nickel ferrite (NiFe2O4) nanoparticles with the size of about 9-20 nm are dispersed evenly on the GO surface denatured by nitrogen. The saturation magnetization of composite NiFe2O4/GO-N is 39,32 emu/g. Photocatalytic activities of the NiFe2O4/N-doped GO composites have been evaluated through the photodegradation of the methyl blue (MB) under the irradiation of a tungsten filament lamp 75 W - 220 V, using a UV filter. MB photodegradation efficiency reaches 98% after 240 minutes of illumination. The NiFe2O4/N-doped GO photocatalysts are recovered under the utilization of an external magnetic field and can be reused. After 3 times of reuse, MB photodegradation efficiency reaches over 87%.

Binder-free hierarchical porous N-doped graphene directly anchored on carbon fiber cloth for high-performance electrochemical energy storage

Abstract A binder-free hierarchical porous N-doped graphene directly anchored on carbon fiber cloth was manufactured by a simple and practical two-step process, in which polyindole/graphene oxide (PIn/GO) composites were prepared by in-situ oxidation polymerization of indole on the surface of GO, and then PIn/GO composites coated on the surface of carbon fiber cloth was activated with KOH at 700 °C. By adjusting the contents of PIn, GO, and KOH, a hierarchical porous P7G-K-2 electrode with N content (4.98 at.%) was obtained and showed lager specific surface area and low interfacial contact resistance. The electrochemical evaluation showed that the P7G-K-2 electrode had a maximum specific capacitance of 451 F g−1 at 1 A g−1 and excellent rate performance. Moreover, a simple supercapacitor consisting of two symmetrical P7G-K-2 electrodes, P7G-K-2//P7G-K-2, was assembled, the specific energy of 21.8 Wh kg−1 can be obtained at the specific power of 75 W kg−1, and it had excellent long-term cycle stability (maintaining 92% initial specific capacitance after 10,000 cycles). The excellent performance indicates that the P7G-K-2 is a promising candidate for supercapacitor electrode materials with high energy output. And this work provides a strategy to fabricate supercapacitors electrode with high specific power and specific energy.

Silica-graphene oxide nanohybrids as reinforcing filler for natural rubber

Hybrid silica-graphene oxide (SiO2@GO) nanocomposites were fabricated by sol-gel method using tetraethylorthosilicate (TEOS) as silica (SiO2) precursor. The prepared nanocomposites were characterized by various analytical techniques to prove that the SiO2 were completely incorporated on the GO surface. Then, the SiO2@GO nanocomposites were introduced into natural rubber (NR) matrix followed by conventional vulcanization process, performed by two-roll mill, to obtain NR/SiO2@GO vulcanizate. The results showed that the presence of SiO2 nanoparticles on the GO surface improved the distribution of GO in NR matrix, resulting in the increase in modulus and hardness. For comparison with neat NR, NR/SiO2, and NR/GO, the network parameters of vulcanizates were evaluated using swelling test and tube model theory contributed in stress-strain measurement. These exhibited that the SiO2@GO induced the chemical crosslink between NR chains, leading to the increment in crosslink density. It was because the well dispersion of SiO2@GO in NR matrix improved the volume fraction of rubber. Moreover, dynamic mechanical analysis was employed to determine the viscoelasticity behavior of the vulcanizates. The results showed that the presence of SiO2@GO in NR vulcanizate improved the storage modulus in all temperature range. That meant the elasticity of the vulcanizates was improved by the reduction of the viscous phase to stiff phase ratio of the material. However, the reinforcement of NR using SiO2@GO as filler was effective in lower deformation reflected from higher modulus at low strain. In addition, the modulus decreased in comparison with that of the neat NR under higher deformation until at break point. Thus, the tensile strength decreased while elongation at break increased. This phenomenon might be explained that the strain-induced crystallization of NR occurred under higher strain was reduced because the rubber chains alignment which was obstructed by the filler penetration and high number of chemical crosslinks. Therefore, the covalent hybrid SiO2@GO nanocomposites had potential for use as filler in engineering rubber composites that were suitable for the compressive or abrasive applications.

Preparation of NH2-SH-GO/SWCNTs based on graphene oxide/single-walled carbon nanotubes for CO2 and N2 separation from blast furnace gas

The traditional molecular sieve membrane for gas separation is mostly prepared by zeolite, MOFs and other materials. Nano-carbon materials such as graphene and carbon nanotubes have been studied in the field of gas separation in recent years which have large specific surface area and high porosity. The performance of carbon nanotubes and graphene can be effectively improved by adding corresponding groups. A novel molecular sieve membrane was synthesized by sulfhydryl and amino-modified graphene oxide/oxidized single-walled carbon nanotubes (NH 2 -SH-GO/SWCNTs). The composite material was characterized by transmission electron microscopy, field emission scanning electron microscopy, X-ray diffraction, thermo-gravimetric analysis, Fourier transform infrared spectroscopy, and Brunauer-Emmett-Teller specific surface area analyzers. The results reveal that laminated graphene oxide and tubular single-walled carbon nanotubes are intertwined and carbon nanotubes attach onto the surface of GO or intercalate into the GO sheets to form a spatial stereoscopic structure. TGA results demonstrate that the loading amount of amino and sulfydryl groups in NH 2 -SH-GO/SWCNTs is about 11.91 wt%. When the intake pressure of N 2 is 0.10 MPa, the permeability coefficient for N 2 passing through NH 2 -SH-GO/SWCNTs is 1829 Barrer. With the increase of temperature, permeability coefficient for N 2 decreases, while it increases as the intake pressure rises. The experimental results for mixed gases passing through NH 2 -SH-GO/SWCNTs show that, when P 0 = 0.10 MPa and T = 323 K, the permeability coefficient for CO 2 is 1896 Barrer, while that for CO is only 116 Barrer. At 323 K, selectivity for N 2 /CO, CO 2 /CO and CO 2 /N 2 is 39.2, 46.3, and 9.3, respectively. These results indicate that NH 2 -SH-GO/SWCNTs may be a promising molecular sieve membrane for gas separation. • Simultaneously separate CO 2 and N 2 from blast furnace gas. • Preparation of new style NH 2 -SH-GO/SWCNTs. • The permeability coefficient for N 2 is 1829 Barrer. • Selectivity for N 2 /CO, CO 2 /CO and CO 2 /N 2 is 39.2, 46.3, and 9.3, respectively.

Fabrication of ZnO–GO hybrid for enhancement of chemically bonded phosphate ceramic coatings corrosion protection performance on AISI304L stainless steel

AbstractIn this paper, a solvothermal method is used to prepare nano‐sized zinc oxide‐graphene oxide (ZnO–GO) hybrid, and the ZnO–GO hybrid is characterized by X‐ray diffraction analysis, Raman, Fourier transform infrared spectroscopy, and scanning electron microscopy. In addition, chemically bonded phosphate ceramics coatings with different content of ZnO–GO hybrid are prepared on the stainless steel through the sol‐gel method. The corrosion performance of the coatings is evaluated by electrochemical properties and the analysis of the surface and cross morphology of the coating. Results indicate ZnO–GO hybrid significantly enhances the compactness and corrosive behavior of the coating because the overlapping structure of GO flake improves the barrier performance of the coating. Besides, ZnO nanoparticles on the surface of GO can react with aluminum dihydrogen phosphate binder, in that case the adhesion between GO and the coating is improved.

Electrochemical performance of Silsesquioxane-GO loaded with alkoxy substituted ammonium-based ionic liquid and POAP for supercapacitor

Recently, the electrochemical efficiency of supercapacitors has experienced a dramatic rise, followed by a rapid developing rate on introducing promising electrode material, led to manufacture highly performance supercapacitors. In this work we synthesized Silsesquioxane -containing graphene oxide (SSQ-GO) and alkoxy substituted ammonium-based ionic liquid, (Tris[2-(2-methoxy ethoxy) ethyl]methyl ammonium Iodide (TMEMAI)) blended with conductive polymer, Poly ortho amino phenol (SSQ-GO- TMEMAI-POAP) used as an electrode in both three and two-electrode systems. The prepared material characterized by XPS, XRD, TEM, SEM, EDX, techniques and the attributed electrochemical tests carried out by cyclic voltammetry, chronopotentiometry techniques. The incorporating of TMEMAI into GO surface with porous structure in the presence of conductive polymer exhibited high conductivity and decreased resistance through the efficient electron channels based on electrochemical impedance spectroscopy test. The specific capacitance and energy density of SSQ-GO-TMEMAI-POAP were significantly improved, while retention capacity obtained ∼96% within 3000 charge-discharge cycles, with high durability. Concerning the two-electrode design, the specific capacitance calculated as 450 F g−1 at 0.5 A g−1, where the energy density at power density achieved of 22.5 W h kg−1, 300 W kg−1, respectively. The incorporation of ionic liquid and conductive polymer within SSQ-GO-TMEMAI-POAP nanocomposite indicated high electrochemical potential where used in energy storage devices.

Improvement of viscoelastic, elastic and plastic properties of Poly(L-lactide)/Graphene Oxide-Graft-Poly(L-lactide) nanocomposites by modulation of grafted chain length

The full potential of poly(L-lactide) (PLLA) reinforced with graphene oxide, GO, nanocomposites tends to be hindered by aggregation of the nanofillers. In order to promote a good dispersion of GO in the PLLA matrix, polymer grafting techniques have been explored to anchor PLLA onto functionalized GO surface to produce GO-PLLA hybrids. For this purpose, PLLA with a terminal triple bond was synthesized by ring-opening polymerization. By controlling the concentration of monomer to initiator, PLLA samples with three different chain lengths have been prepared and later coupled to azide-functionalized GO using click chemistry. These hybrids were then mixed with commercial PLLA and cast films have been prepared. The ensuing nanocomposite films were studied using Depth Sensing Indentation and the results have shown that PLLA matrix-filler interaction can be modulated by controlling the chain length of PLLA graft. This is a critical point because the enhancement of these interactions provides a stronger matrix-filler interphase which improves the stress transfer between both phases and increases the contribution of the interphase to the stiffening of the nanocomposites. Therefore, it has been proven that judicious functionalization of GO is an effective procedure for improving the strength, the stiffness and the creep resistance of the PLLA composites.

Molybdate intercalated hydrotalcite/graphene oxide composite as corrosion inhibitor for carbon steel

Molybdate intercalated hydrotalcite/graphene oxide composite (HT-MoO4/GO) as corrosion inhibitor for carbon steel was synthesized and characterized. The influence of HT-MoO4/GO on corrosion resistance of waterborne epoxy coating applied on carbon steel was investigated. The results showed that hydrotalcite containing molybdate was formed on GO surface and the molybdate content in HT-MoO4/GO was 15.3%. HT-MoO4/GO provided both anodic and cathodic inhibition effects for carbon steel with an efficiency of 96%. The corrosion inhibition of HT-MoO4/GO depended not only on the inhibition effect of released molybdate but also on the deposition of HT-MoO4/GO particles on the steel surface. HT-MoO4/GO at 1 wt% concentration improved corrosion resistance of waterborne epoxy coatings. The presence of GO increased the effects of HT-MoO4 on protection properties of waterborne epoxy coatings.

Arbitrary-shaped reduced graphene oxide aerogels via an unsaturated water vapor reduction

It still remains a challenge to explore facile, economic, and environmental friendly process for the fabrication of graphene aerogels with low density and high purity to meet the various applications. Herein, arbitrary-shaped reduced graphene oxide (rGO) aerogels are prepared by freeze-drying process and followed unsaturated water vapor reduction method staring from GO aqueous suspensions for the first time. Water vapor hydrothermal treatment can decompose all oxygen-containing functional groups in GO and repair GO surface defects effectivly. At higher temperatures (≥175 °C), the carbon in GO may react with water vapor via water-gas shift reaction to form CO, which could also be used as the reductant for the reduction of GO aerogels. The water volume as well as the temperature are key parameters for realizing high reduction degree as well as good shape control of rGO aerogels. Arbitrary shaped rGO aerogels could be prepared by using various molds for freezing GO suspensions. rGO aerogels exhibit a high oil/water separation performance, which could absorb various oils up to 40-55 times of its initial weight with high recyclability. Moreover, the rGO aerogels exhibit typical pressure sensing behavior and excellent energy storage capacitance, which hold great potential applications in flexible pressure sensors and supercapacitors.

Solid-Phase Microwave Reduction of WO3 by GO for Enhanced Synergistic Photo-Fenton Catalytic Degradation of Bisphenol A.

The synergistic photocatalytic Fenton reaction is a powerful advanced oxidation technique for the degradation of persistent organic pollutants. However, microwave-induced thermal effects on the formation of novel structures facilitating the photocatalytic degradation have been rarely reported. Herein, a two-step microwave thermal strategy was developed to synthesize a new hybrid catalyst comprising defective WO3-x nanowires coupled with reduced graphene oxides (rGOs). Conventionally, microwave methods could induce superhot spots on the GO surface, resulting in the site-specific crystallization and oriented growth of WO3. However, in the solid phase, localized microwave thermal effects could reduce the interfacial area between WO3 and rGO and enhance the bonding between them. As for the unique structure and surface properties, the synthesized catalyst enhanced the light absorption, promoted the interfacial charge separation, and increased the carrier density in the photocatalytic processes. In addition, surface formation of W4+ provided a new pathway for Fe3+/Fe2+ cycling which linked the photocatalytic reaction and the Fenton process. The optimized catalyst exhibited a remarkable performance in the degradation of bisphenol A with a ∼83% removal yield via a photo-Fenton route. These microwave-induced functionalities of materials for synergistic reactions could also give a new avenue to other photoelectrocatalytic fields and solar cells.

Graphene oxide in the remediation of norfloxacin from aqueous matrix: simultaneous adsorption and degradation process.

In the present study, the simultaneous adsorption degradation of norfloxacin (NOR) by graphene oxide from aqueous matrix was verified. Graphene oxide (GO, ~ 8 layers) was prepared using modified Hummers method through the oxidation/exfoliation of expanded graphite. Spectroscopic techniques confirmed the NOR adsorption onto GO surface and the partial antibiotic degradation promoted by hydroxyl radicals derived from GO. Furthermore, the mass spectra after the adsorption-degradation processes showed NOR degradation intermediates that was compared and confirmed by other studies. The nanomaterial showed a removal capacity of 374.9 ± 29.8mg g-1, observing greater contribution from the NOR in the zwitterionic form and removals up to 94.8%. The intraparticle diffusion process, assessed by Boyd's model and Fick's law, presented a greater contribution in the removal process, reaching the equilibrium 30min after the beginning. In addition, the temperature increase would disadvantage the process, which was considered thermodynamically viable throughout the evaluated temperature range. Finally, the process was scaled-up in a single stage batch adsorber considering a NOR removal efficiency of 95%. This resulted in mass requirement of 63.6g of GO in order to treat 0.5m3 of contaminated water. In general, the simultaneous adsorption-degradation process was considered innovative and promising in pharmaceutical compounds remediation.

Influence of GO-Al2O3 hybrid material on the tribological behavior of chemically bonded ceramic coating

GO-Al2O3 hybrid material was prepared to enhance the bond strength between GO and chemically bonded ceramic coating (CBCC). TEM and FTIR results indicate that nano Al2O3 is successfully grafted to the surface of GO via chemical bonds. Besides, the tribological behavior of CBCC with GO-Al2O3 hybrid material was investigated. The results show that the friction coefficient and wear rate of CBCC decrease with the introduction of GO-Al2O3 hybrid material. In addition, the formation of debris becomes difficult as the cohesive strength of CBCC increases with the introduction of GO-Al2O3 hybrid material, which can improve the wear resistance of CBCC. Furthermore, because less debris on the worn surface makes bigger real contact surface against the counter ball than that of CBCC without GO-Al2O3 hybrid material, the contact stress obviously decreases, contributing to high wear resistance.

Synthesis and Application of Novel Nano Fe-BTC/GO Composites as Highly Efficient Photocatalysts in the Dye Degradation

Nano Fe-BTC/graphene oxide (GO) composites were successfully synthesized by hydrothermal treatment with a microwave-assisted method. Samples were characterized by X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), N2 adsorption–desorption, Scanning electron microscopy (SEM), Energy-dispersive X-ray spectroscopy (EDS), and Ultraviolet–visible diffuse reflection spectroscopy (UV–Vis DRS). SEM image of Fe-BTC/GO-30 showed the particle size of 30–50 nm on the GO surface. From the UV–Vis diffuse reflectance spectra, it revealed that nano Fe-BTC/GO composite absorbed the wavelengths in the visible light region with a low bandgap energy of 2.2–2.45 eV. Fe-BTC/GO nanocomposites were tested for the photocatalytic degradation of reactive yellow 145 (RY-145) in aqueous solution. Fe-BTC/GO composites exhibited high photocatalytic activity. Thus, at pH of 3 and high initial concentration of 100 mg RY-145/L, removal efficiency reached the value of 98.18% after 60 min. of reaction. In comparison with Fe-BTC/GO synthesized by the solvothermal method, nano Fe-BTC/GO showed much higher RY-145 removal efficiency. Moreover, this Fe-BTC/GO-30 showed high catalytic activity stability and could be reused, opening the high potential application of this promising photo-Fenton catalyst in photocatalytic degradation of organic pollutants from aqueous solution.

In situ green growth of uniform and naked Ag nanoparticles on graphene oxide at room temperature and its enhanced catalytic performance

In situ growth of naked Ag nanoparticles on graphene oxide was achieved following a simple, green, and environment-friendly one-step stirring method. In the absence of extra reductant and stabilizer, the naked Ag nanoparticles formed on the surface of GO via a spontaneous redox reaction between Ag+ and GO at room temperature. The morphology and microstructure of the resultant heterogeneous nanostructures were characterized by various spectroscopic and microscopic techniques systematically. The characterization results showed that the naked metallic Ag nanoparticles with an average diameter of 4.31 ± 0.13 nm distribute homogeneously and tend to “stand” in line on GO. The well-known catalytic hydrogenation of 4-nitrophenol by NaBH4 was carried out to investigate the potential catalytic activity of the obtained heterogeneous Ag/GO nanocomposite. The obtained Ag/GO nanocomposite exhibited high catalytic ability with the apparent kinetics constant of 1.856 min−1 and high turnover frequency of 2131.6 h−1 and high structural and performance stability. It is believed that the small size and naked surface of the Ag nanoparticles, which provide abundant exposed catalytically active sites, facilitate greatly in improving the catalytic performance of Ag/GO. It is anticipated that the proposed green method is extendible to prepare other efficient noble-metal/GO nanocatalyst.

Surface functionalization of graphene oxide using amino silane magnetic nanocomposite for Chromium (VI) removal and bacterial treatment

Amino silane magnetic nanocomposite decorated on graphene oxide (GO-Fe3O4-APTES) was successfully prepared by organic transformation reaction followed by co-precipitation method. The nanocomposite was characterised by using FT-IR, XRD, FE-SEM, TEM, EDS mapping, VSM, Raman spectroscopy, BET surface area analyzer, Zeta potential and UV-visible spectrophotometer. From TEM results we observed that 8 nm sized particles successfully modified on GO surface. The surface area of GO-Fe3O4-APTES was 57.9 m2 g−1. The magnetic Saturation value of GO-Fe3O4-APTES was 30.6 emu g−1 and the S-like magnetization of all the samples shows super paramagnetic in nature. Due to magnetic nature adsorbent, it could be easily separated from aqueous solution. GO-Fe3O4-APTES material was highly selective for Chromium (VI) removal from aqueous solution. About 91% of Chromium (VI) was removed at pH 3, 160 rpm of shaking speed, 0.3 g l−1 of adsorbent dose and 10 h of contact time. The adsorption process of Chromium (VI) on GO-Fe3O4-APTES follows Pseudo-second-order kinetic and Langmuir isotherm model because of high coefficient of determination value (R2 = 0.99). The maximum adsorption capacity (qm) of GO-Fe3O4- APTES was observed at 60.53 mg g−1. The synthesized material was desorbed with 0.5 M NaOH and recycled up to five cycles. After five cycles, the removal efficiency of Chromium (VI) possesses high efficacy towards GO-Fe3O4-APTES. Mechanistically, adsorption of Chromium (VI) follows strong electrostatic attraction between adsorbate and adsorbent. GO-Fe3O4-APTES has potential adsorbent for the adsorption of Chromium (VI) in waste water treatment. Furthermore, the GO-Fe3O4-APTES were tested for antibacterial properties against gram negative (Escherichia coli) and gram positive (Bacillus subtilis) bacterial strain. The synthesized material responds positively towards antibacterial activity.

Graphene oxide nanofilm and the addition of l-glutamine can promote development of embryonic muscle cells

BackgroundFormation of muscular pseudo-tissue depends on muscle precursor cells, the extracellular matrix (ECM)-mimicking structure and factors stimulating cell differentiation. These three things cooperate and can create a tissue-like structure, however, their interrelationships are relatively unknown. The objective was to study the interaction between surface properties, culture medium composition and heterogeneous cell culture. We would like to demonstrate that changing the surface properties by coating with graphene oxide nanofilm (nGO) can affect cell behaviour and especially their need for the key amino acid l-glutamine (L-Glu).ResultsChicken embryo muscle cells and their precursors, cultured in vitro, were used as the experimental model. The mesenchymal stem cell, collected from the hind limb of the chicken embryo at day 8 were divided into 4 groups; the control group and groups treated with nGO, L-Glu and nGO supplied with L-Glu (nGOxL-Glu). The roughness of the surface of the plastic plate covered with nGO was much lower than a standard plate. The test of nGO biocompatibility demonstrated that the cells were willing to settle on the nGO without any toxic effects. Moreover, nGO by increasing hydrophilicity and reducing roughness and presumably through chemical bonds available on the GO surface stimulated the colonisation of primary stromal cells that promote embryonic satellite cells. The viability significantly increased in cells cultured on nGOxL-Glu. Observations of cell morphology showed that the most mature state of myogenesis was characteristic for the group nGOxL-Glu. This result was confirmed by increasing the expression of MYF5 genes at mRNA and protein levels. nGO also increased the expression of MYF5 and also very strongly the expression of PAX7 at mRNA and protein levels. However, when analysing the expression of PAX7, a positive link was observed between the nGO surface and the addition of L-Glu.ConclusionsThe use of nGO and L-Glu supplement may improve myogenesis and also the myogenic potential of myocytes and their precursors by promoting the formation of satellite cells. Studies have, for the first time, demonstrated positive cooperation between surface properties nGO and L-Glu supplementation to the culture medium regarding the myogenic potential of cells involved in muscle formation.

A Rotavirus Virus-Like Particle Confined Palladium Nanoreactor and Its Immobilization on Graphene Oxide for Catalysis

In this work, a new viral protein cage based nanoreactor was successfully constructed via encapsulating Tween 80 stabilized palladium nanoparticles (NPs) into rotavirus capsid VP2 virus-like particles (i.e. Pd@VP2). The effects of stabilizers including CTAB, SDS, Tween 80 and PVP on controlling the particle size of Pd NPs were investigated. They were further immobilized on graphene oxide (i.e. Pd@VP2/GO) by a simple mixing method. Some characterizations including FT-IR and XPS were conducted to study adsorption mode of Pd@VP2 on GO sheets. Their catalytic performance was estimated in the reduction of 4-nitrophenol (4-NP). Results showed that Tween 80 stabilized Pd NPs with the molar ratio of Pd to Tween 80 at 1:0.1 possessed the smallest size and the best stability as well. They were encapsulated into viral protein cages (mean size 49 ± 0.26 nm) to assemble confined nanoreactors, most of which contained 1–2 Pd NPs (mean size 8.15 ± 0.26 nm). As-prepared Pd@VP2 indicated an enhanced activity (apparent reaction rate constant kapp = (3.74 ± 0.10) × 10−3 s−1) for the reduction of 4-NP in comparison to non-confined Pd-Tween80 colloid (kapp = (2.20 ± 0.06) × 10−3 s−1). It was logically due to confinement effects of Pd@VP2 including high dispersion of Pd NPs and high effective concentration of substrates in confined space. Pd@VP2 were further immobilized on GO surface through C-N bond. Pd@VP2/GO exhibited good reusability after recycling for four runs, confirming the strong anchoring effects of GO on Pd@VP2.Graphic Electronic supplementary materialThe online version of this article (10.1007/s10562-020-03252-6) contains supplementary material, which is available to authorized users.

Construction of a unique anti-corrosion nanocomposite based on graphene oxide@Zn3PO4/epoxy; experimental characterization and detailed-theoretical quantum mechanics (QM) investigations

The highly crystalline zinc phosphate (ZnP) compounds were synthesized over the graphene oxide surface through one and two-steps in-situ methods (namely GO-ZnP I and II). FT-IR studies revealed that the CO peak weakened or completely removed in the GO-ZnP I, II samples. Raman spectroscopy results evidenced the higher ID/IG ratio for the unmodified GO than GO-ZnP I and II, confirming the zinc phosphate crystals growth on the GO surface. Results of XPS and Raman spectroscopy proved the GO-ZnP I and II crystals formation on the GO platelets. ICP analysis results depicted about 11.6 ppm and 10.7 ppm zinc ions presence in NaCl solution, evidencing the partial solubility of the GO-ZnP I and for GO-ZnP II particles. A smart self-healing nanocomposite coating with promising anti-corrosion effect and dual active/barrier functions was designed using GO-ZnP I and II nanosheets. EIS studies on mild steel samples exposed to the saline solutions containing GO-ZnP I and GO-ZnP II particles extract demonstrated inhibition efficiencies of about 76 and 69%, respectively. According to EIS analysis, the total resistance (Rt) values of 11480, 12048, 9105, and 7512 Ω·cm2 were recorded for the EP/GO-ZPII, EP/GO-ZPI, neat epoxy, and EP/GO samples, respectively, after 48 h of exposure to saline solution confirming the superior anti-corrosion performance of the scratched EP in the presence of GO-ZP particles. The GO-ZPII loaded epoxy matrix showed low-frequency impedance values greater than 1010 Ω·cm2 even after 39 days of exposure, indicating the superior barrier effect of the particles in the coating formulation. The EIS evaluation and accelerated salt-fog spray corrosion test results showed the effectiveness of GO-ZnP II and I composites (at 0.15 wt% loading) in epoxy coating active inhibitive/barrier performance promotion. Additionally, the theoretical density functional theory (DFT) results declared the zinc phosphate adsorption on the GO surfaces.

Three-Dimensional Graphene Oxide-Supported Zinc Oxide Scaffold as a High-Efficiency Adsorbent for Desulfurization

Sulfur oxides are air pollutants derived mainly from the combustion of gasoline. Reducing the sulfur content of fluid catalytic cracking (FCC) gasoline is of key importance for the prevention and control of atmospheric pollution. We describe herein the fabrication and characterization of a porous, three-dimensional (3D) graphene oxide-supported zinc oxide (GO/ZnO) scaffold as an adsorbent for desulfurization with various model compounds and real FCC gasoline. The uniform and stable dispersion of ZnO nanoparticles on the surface of GO facilitates the specific binding of sulfides. Moreover, GO synergistically adsorbs aryl sulfides via [Formula: see text]–[Formula: see text] stacking interactions. The GO/ZnO nanosheets were further self-assembled into a 3D porous scaffold that effectively trapped sulfides and inhibited desorption. These scaffolds exhibited excellent desulfurization performance with maximum sulfur capacity up to 29.73[Formula: see text]mg S/g. This work provides a novel perspective on the fabrication of high-efficiency adsorbents for gasoline pretreatment.