Functional Reduced Graphene Oxide Research Articles

An epoxy-modified polyurethane composite coating with repetitive self-healing function for anti-cavitation, anticorrosion, and antifouling applications

Erosion and fouling are important factors that affect the performance of power components of large cargo ships. Inspired by animal cartilage tissue, an epoxy modified polyurethane composite coating (FD-EPU) with reproducible self-healing properties was successfully prepared. FD-EPU was endowed with excellent resistance to cavitation, corrosion, and fouling due to the presence of functional reduced graphene oxide (FrGO) and 2-octyl-4,5-dichloroisothiazolinone (DCOIT). The introduction of FrGO with multiple hydrogen bonds into coatings increased the tensile strength of FD-EPU by 3.56 MPa and exhibited excellent cavitation resistance (with a mass loss of 4.7 mg under continuous cavitation for 60 h). In addition, the barrier effect of FrGO enabled FD-EPU to possess outstanding anticorrosion ability. After being immersed in 3.5 wt% NaCl for a duration of 15 days, the |Z|0.01Hz value of FD-EPU was found to remain at 9.18 × 109 Ω·cm2. The modification of epoxy resulted in FD-EPU coatings with improved adhesion by 53.5 % compared to non-modified coatings, with a bond strength of 23.8 MPa on stainless steel. The incorporation of DCOIT and FrGO endowed FD-EPU with good antifouling properties (removal of more than 97.5 % of bacteria and removal rate of microalgae up to 96.2 %). Furthermore, FD-EPU exhibited outstanding opto-thermal self-healing capability, with a self-healing efficiency of 61 % after 30 s of near-infrared light irradiation. This work provides a new inspiration for the protection of large cargo ship power components.

Antifouling and anticorrosion function of repeatable self-healing polyurethane composite inspired by the self-healing principle of cartilage tissue

Micro-cracking caused by the impact of gravel in the ocean is an important factor affecting the longevity of the integrated antifouling and anticorrosion coating. Inspired by the animal cartilage tissue, a series of polyurethane composite coatings (MPU-FrGO) with repeatable self-healing functions were successfully prepared. MPU-FrGO are endowed with excellent antifouling and anticorrosion ability because they contain functional reduced graphene oxide (FrGO) and 2-methyl 4-isothiazoline 3-ketone (MIT). As animal cartilage tissues, two-dimensional structure of FrGO forms hydrogen bond crosslinking and chemical crosslinking with polyurethane in MPU-FrGO. The super strong spatial network endows MPU-FrGO3 (the amount of FrGO added is 1 wt%) with excellent mechanical properties and strong self-healing ability. Its stress (35.6 MPa) and strain (861%) is far more than that of PU-FrGO0 (27.2 MPa and 762%). MPU-FrGO3 showed exceptional self-healing performance, and the self-healing efficiency could reach 91% (91% of initial stress) after 15 min of NIR irradiation; the self-healing efficiency of five cycles can reach more than 83% (83% of initial stress). The |Z|0.01Hz of MPU-FrGO3 can still maintain 3.34 × 108 Ω·cm2 after immersed in 3.5 wt% NaCl for 15 days because of the excellent barrier performance of FrGO. Owing to the excellent antibacterial and anti-algal functions of FrGO and MIT, the antibacterial ability and algae inhibition coverage ability of MPU-FrGO3 were 99.5% and 97.1%, respectively. The work provides a heuristic perspective for the design of polymer materials with anticorrosion, antifouling, and self-healing.

Antioxidant, Anti-Bacterial, and Congo Red Dye Degradation Activity of AgxO-Decorated Mustard Oil-Derived rGO Nanocomposites.

Scaling up the production of functional reduced graphene oxide (rGO) and its composites requires the use of low-cost, simple, and sustainable synthesis methods, and renewable feedstocks. In this study, silver oxide-decorated rGO (AgxO−rGO) composites were prepared by open-air combustion of mustard oil, essential oil-containing cooking oil commercially produced from the seeds of Brassica juncea. Silver oxide (AgxO) nanoparticles (NPs) were synthesized using Coleus aromaticus leaf extract as a reducing agent. Formation of mustard seed rGO and AgxO NPs was confirmed by UV-visible characteristic peaks at 258 nm and 444 nm, respectively. rGO had a flake-like morphology and a crystalline structure, with Raman spectra showing clear D and G bands with an ID/IG ratio of 0.992, confirming the fewer defects in the as-prepared mustard oil-derived rGO (M−rGO). The rGO-AgxO composite showed a degradation efficiency of 81.9% with a rate constant k−1 of 0.9506 min−1 for the sodium salt of benzidinediazo-bis-1-naphthylamine-4-sulfonic acid (known as the azo dye Congo Red) in an aqueous solution under visible light irradiation. The composite also showed some antimicrobial activity against Klebsilla pneomoniae, Escherichia coli, and Staphylococcus aureus bacterial cells, with inhibition zones of ~15, 18, and 14 mm, respectively, for a concentration of 300 µg/mL. At 600 µg/mL concentration, the composite also showed moderate scavenging activity for 2,2-diphenyl-1-picrylhydrazyl of ~30.6%, with significantly lower activities measured for AgxO (at ~18.1%) and rGO (~8%) when compared to control.

Graphene-based nanocomposites and nanohybrids for the abatement of agro-industrial pollutants in aqueous environments

Incessant release of a large spectrum of agro-industrial pollutants into environmental matrices remains a serious concern due to their potential health risks to humans and aquatic animals. Existing remediation techniques are unable to remove these pollutants, necessitating the development of novel treatment approaches. Due to its unique structure, physicochemical properties, and broad application potential, graphene has attracted a lot of attention as a new type of two-dimensional nanostructure. Given its chemical stability, large surface area, electron mobility, superior thermal conductivity, and two-dimensional structure, tremendous research has been conducted on graphene and its derived composites for environmental remediation and pollution mitigation. Various methods for graphene functionalization have facilitated the development of different graphene derivatives such as graphene oxide (GO), functional reduced graphene oxide (frGO), and reduced graphene oxide (rGO) with novel attributes for multiple applications. This review provides a comprehensive read on the recent progress of multifunctional graphene-based nanocomposites and nanohybrids as a promising way of removing emerging contaminants from aqueous environments. First, a succinct overview of the fundamental structure, fabrication techniques, and features of graphene-based composites is presented. Following that, graphene and GO functionalization, i.e., covalent bonding, non-covalent, and elemental doping, are discussed. Finally, the environmental potentials of a plethora of graphene-based hybrid nanocomposites for the abatement of organic and inorganic contaminants are thoroughly covered.

One-Pot Purification and Immobilization of Phenylalanine Dehydrogenase from Bacillus nanhaiensi by Functional Reduced Graphene Oxide.

The one-pot immobilization of halophilic phenylalanine dehydrogenase from marine microorganism with metal ions modified reduced graphene oxide (CRGO) material was studied. Phenylalanine dehydrogenase was from Bacillus nanhaiensi and expressed with a C-terminal His-tag. Investigation of CRGO, CRGO-PEI, CRCO-Mn, and CRGO-PEI-Mn for one-pot purification and immobilization of phenylalanine dehydrogenase from crude enzyme solution was carried out. Enzyme activity yield rate achieved 80.0% by immobilization with CRCO-Mn, and the loading capacity was 6.7mg/mg. Manganese ion coordination greatly improved the selectivity of the CRGO for the target His-tagged enzyme. Furthermore, the effect of NaCl concentration on the immobilization was investigated, which the loading capacity of CRGO-PEI and CRGO-Mn-PEI was increased by 10.7% and 30.6% with 1M NaCl, respectively. The adsorption curves of crude enzyme one-pot immobilized by CRGO-Mn and purified enzyme immobilized by CRGO-Mn were similar. Therefore, one-pot immobilization strategy is promising for industrial application with advantages such as high efficiency and low cost, which shorten the pipelines for enzyme discovery towards industrial applications through the establishing of marine enzyme collections.

Bioinspired Reduced Graphene Oxide Based Nanohybrids for Photocatalysis and Antibacterial Applications.

Ultra-thin graphene has been receiving significance in the diverse sections of material science, owing to its exceptional physicochemical and thermo-mechanical characteristics. Currently, the fabrication of high-grade graphene in an economical target and green procedures area is a massive concern. Among the diverse techniques, chemical-mediated fabrication is believed to be the finest process since it is simple, scalable, and of low-cost; however, it involves noxious or hazardous chemical reducers for producing functional graphene-based Nanocomposites (NCs). Therefore, around the globe, scientists are endeavoring to adopt the bioinspired techniques to manufacture the functional reduced Graphene Oxide (rGO) and reduced Graphene Oxide-Metal/Metal Oxide (rGO-M/MO) NCs. Hence, keeping this issue in mind, the present review article summarize and integrates the current state of knowledge about the diverse bioinspired strategies developed to obtain rGO and rGO-M/MO NCs and their photocatalytic, antibacterial, and cytotoxic assessments.

Removal of dissolved organic carbon by functional reduced graphene oxide from organic– rich water pre-treated by electrocoagulation

Removal of dissolved organic carbon by functional reduced graphene oxide from organic– rich water pre-treated by electrocoagulation

A high performance and flexible in-plane asymmetric micro-supercapacitor (MSC) fabricated with functional electrochemical-exfoliated graphene

With the increasing development of miniaturized, integrated, wearable and portable electric devices, in-plane micro-supercapacitors (MSCs), as one of most potential next-generation energy storage setups, have attracted abundant interests from the public. In this study, a flexible in-plane asymmetric MSC, prepared by the mask-assisted vacuum filtration, was demonstrated. Furthermore, the electrochemical-exfoliated functional graphene oxide (FGO) and chemical-reduced functional reduced graphene oxide (FrGO) were configured as positive and negative electrode of the MSCs, coated with the solid PVA/Na2SO4 electrolyte. The result presented that the as-assembled FGO-FrGO MSCs performed the highest areal capacitance of 7.3 mF cm−2. It was assumed that the high performance of the asymmetric MSCs was attributed to the asymmetric in-plane interdigitated structure, the abundant functional groups doping and heteroatoms replacement with N, O, P, S elements in graphene. In summary, the functional graphene-based asymmetric MSCs provide a potential inspiration for the next-generation flexible and wearable energy storage devices.

An Approach in EME: Development of Thermal and Electrical Conductivities of Membrane and Disable the Chemical Carrier in Transport Process

In this study, amine functional reduced graphene oxide (rGO-fNH2) and modified membrane was synthesized in an attempt to provide a thermal and mechanical contribution to their present performances by achieving more productive and stable membranes with the improvement of the membrane systems. So, the transport of the metal cation Cr(VI) was realized. The productivity of the membrane was increased by the transport process being realized without using a carrier on the membrane phase by modifying the membrane with rGO-fNH2. Thus, it was proved that a more productive division can be applied on a wider temperature range.When the conductivity values of the membrane were measured between 265–330 K and compared by adding different rGO-fNH2values (18.52–15.38–12.00%–8.33% w/w) to the membrane, it was seen that the conductivity values of all except for the one with the lowest compound was extremely high between these temperature ranges. Another point is that the membrane prepared as 8.33% w/w had a semi conductive feature. By applying electrical current to the membranes with polymer content (PIM) which are examples of liquid applications, the process transport time duration known as electromembrane extraction (EME) was reduced to minutes from hours. The optimized membrane includes 51.85% 2-nitrophenyl octyl ether (2-NPOE), 29.63% cellulose triacetate (CTA), 18.52% rGO-fNH2. Besides, in the experiment in which the membrane compound was 18.52 w/w; 0.5 A and 60 V was applied and within 90 min 97.41% Cr(VI) was removed from the donor phase. For a more stable process, we performed experiments with constant current instead of constant voltage. The fact that the membrane stability was over 90% even after 30 repetitions obviously showed the positive effect of the rGO-fNH2 added to the membrane.

Design and Synthesis of Double-Functional Polymer Composite Layer Coating To Enhance the Electrochemical Performance of the Ni-Rich Cathode at the Upper Cutoff Voltage.

Graphene has been implemented as a desirable additive to improve the electrochemical performance of Ni-rich cathode materials. However, it is not only hard to ensure the intimate interaction between them in practice, which may affect the surface electronic conductivity of the composite, but also a challenge to fabricate cathodes with uniform graphene coating because of its two-dimensional planar structure. Besides, the graphene coating layer is easily peeled off from the cathode material during the cycling process, especially at the upper cutoff voltage. Therefore, we introduced a double-functional layer synergistically modified strategy to facilitate the electrochemical properties of LiNi0.8Co0.1Mn0.1O2 cathode materials. In the designed architecture, the LiNi0.8Co0.1Mn0.1O2 particles were uniformly enwrapped by a functional reduced graphene oxide (RGO)-KH560 polymer composite layer which consists of an inner high-flexibility epoxy-functionalized silane (KH560) layer and an outer RGO layer with high electronic conductivity. The KH560 layer, in the structural system, is especially critical in connecting the layer of outer RGO and the inner surface of the active material, which brings about the perfect and complete double-functional coating layer and in turn fully expresses the modification effect of both KH560 and RGO in the improvement of electrochemical performance. Consequently, higher capacity retention, better rate, and improved high-temperature performances (55 °C) at the upper cutoff voltage (4.5 V) of this composite are identified when compared with the RGO-coated and pristine samples. In particular, the cathode with RGO (0.5%)-KH560 (0.5%) coating exhibits capacity retentions of 95.2 and 81.5% after 150 cycles at 1 C, 4.5 V at room and high temperatures, respectively.

Electroactive Conjugated Polymer / Magnetic Functional Reduced Graphene Oxide for Highly Capacitive Pseudocapacitors: Electrosynthesis, Physioelectrochemical and DFT Investigation

Electroactive Conjugated Polymer / Magnetic Functional Reduced Graphene Oxide for Highly Capacitive Pseudocapacitors: Electrosynthesis, Physioelectrochemical and DFT Investigation

Electroactive Conjugated Polymer / Magnetic Functional Reduced Graphene Oxide for Highly Capacitive Pseudocapacitors: Electrosynthesis, Physioelectrochemical and DFT Investigation

Electroactive Conjugated Polymer / Magnetic Functional Reduced Graphene Oxide for Highly Capacitive Pseudocapacitors: Electrosynthesis, Physioelectrochemical and DFT Investigation

Polydopamine functional reduced graphene oxide for enhanced mechanical and electrical properties of waterborne polyurethane nanocomposites

Waterborne polyurethane/polydopamine (PDA) functional reduced graphene oxide (WPU/PDRGO) nanocomposites were prepared by in situ emulsification method. The presence of a PDA layer and the partial reduction of GO by PDA were confirmed by FTIR, XRD, Raman spectra, and TGA. It was found that the interfacial PDA layers facilitated the dispersion of the PDRGO sheets in the WPU matrix and enhanced mechanical properties of the WPU matrix. The resulting WPU/PDRGO nanocomposite coatings show excellent electrical conductivity (9.9 × 10−6–1.1 × 10−4 S cm−1) corresponding to a PDRGO content of 1–16 wt%. The obtained waterborne polyurethane/graphene nanocomposite dispersions are promising for anticorrosion, antistatic, conductive, and electromagnetic interference shielding coatings.

Flexible polymer solar cells based on Ag metallic grids and functional reduced graphene oxide composite electrode

By combining the appropriate Ag metallic grids with a thin functional reduced graphene oxide (MGs/F-rGO) film, a suitable photoelectric flexible electrode of the polymer solar cells (PSCs) is obtained. The conductivity and transmission of the MGs/F-rGO composited films can be improved by HNO3 modified. The optimized sheet resistance and transmission of the flexible electrode achieve to 25 Ω □−1 and 83% at 550 nm wavelength. Flexible PSCs with the MGs/F-rGO electrode show 5.63% power conversion efficiency. The photoelectric properties of the MGs/F-rGO film comparable with that of ITO substrates guarantee a high short current and an enhanced PCE of the solar cells. This method provides a feasible way for fabricating low-cost and flexible PSCs.

In Situ Growth of Clean Pd Nanoparticles on Polystyrene Microspheres Assisted by Functional Reduced Graphene Oxide and Their Excellent Catalytic Properties.

Herein an in situ growth of clean palladium nanoparticles (Pd NPs) on functional reduced graphene oxide (RGO)-coated polystyrene (PS) microspheres is achieved by a simple two-step process. On the basis of the hydrophobic interaction and π-electron interaction, the PS/RGO composite particles are first prepared by the reduction of graphene oxide in the presence of PS microspheres. Second, without using any additional reducing agent or stabilizer, the clean Pd NPs grow in situ on the surface of PS/RGO composite particles in water through a spontaneous redox reaction between Pd2+ and RGO. Significantly, owing to the stabilizer-free surface of Pd NPs and the synergistic effect of RGO and Pd NPs, the resultant PS/RGO@Pd composite particles feature pronounced catalytic activity toward the reduction of p-nitrophenol and Suzuki coupling reactions. Moreover, the catalyst particles can be easily recovered by centrifugation because of the large size of support microspheres and recycled consecutively.

Preparation of functional reduced graphene oxide and its influence on the properties of polyimide composites

ABSTRACTHomogeneous dispersion and strong filler–matrix interfacial interactions were vital factors for graphene for enhancing the properties of polymer composites. To improve the dispersion of graphene in the polymer matrix and enhance the interfacial interactions, graphene oxide (GO), as an important precursor of graphene, was functionalized with amine‐terminated poly(ethylene glycol) (PEG–NH2) to prepare GO–poly(ethylene glycol) (PEG). Then, GO–PEG was further reduced to prepare modified reduced graphene oxide (rGO)–PEG with N2H4·H2O. The success of the modification was confirmed by Fourier transform infrared spectroscopy, thermogravimetric analysis, and Raman spectroscopy. Different loadings of rGO–PEG were introduced into polyimide (PI) to produce composites via in situ polymerization and a thermal reduction process. The modification of PEG–NH2 on the surface of rGO inhibited its reaggregation and improved the filler–matrix interfacial interactions. The properties of the composites were enhanced by the incorporation of rGO–PEG. With the addition of 1.0 wt % rGO–PEG, the tensile strength of PI increased by 81.5%, and the electrical conductivity increased by eight orders of magnitude. This significant improvement was attributed to the homogeneous dispersion of rGO–PEG and its strong filler–matrix interfacial interactions. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017, 134, 45119.

Preparation of a functional reduced graphene oxide and carbon nanotube hybrid and its reinforcement effects on the properties of polyimide composites

ABSTRACTThe homogeneous dispersion and strong interfacial interactions of carbon nanomaterials are vital factors on enhancing the properties of polymer composites. Two‐dimensional reduced graphene oxide (rGO) and one‐dimensional carbon nanotubes (CNTs) were first grafted by 4,4′‐oxydianiline (ODA). The successful grafting of ODA onto the rGO and CNTs were confirmed by Fourier transform infrared spectroscopy, thermogravimetric analysis, and X‐ray photoelectron spectroscopy. The hybrid carbon nanomaterials of the functionalized CNTs and rGO with different ratios were prepared via a solution‐mixing method, and their dispersion state was investigated. The hybrid carbon nanomaterials with good stability were introduced to polyimide (PI) via in situ polymerization. The morphology and properties of the polymer composites were studied. The results show that much better mechanical and electrical properties of the composites could be achieved in comparison with those of the neat PI. An improvement of 100.7% on the tensile strength and eight orders for the electrical conductivity were achieved at only a 1.0 wt % hybrid content. A significant enhancement effect was attributed to the homogeneous dispersion of the filler, filler–matrix strong interfacial interactions, and unique structure of the hybrid carbon nanomaterials in the composites. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017, 134, 44575.

Simultaneous reduction and surface functionalization of graphene oxide for enhancing flame retardancy and thermal conductivity of mesogenic epoxy composites

Graphene oxide (GO) is reduced and surface functionalized by 9, 10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide (DOPO) simultaneously. This functional reduced graphene oxide (F-rGO) with better thermal stability can be used as nano-filler to improve flame retardancy, mechanical properties and thermal conductivity of mesogenic epoxy (EO). Due to the presence of oriented structure, EO is an intrinsic high thermal conductive polymer compared with common polymer. After filled with F-rGO, the ordered domains in EO matrix are connected by F-rGO. As a result, thermal conductivity coefficient of F-rGO/EO composite is increased by 30.8% compared with pure EO. DMA result indicates that E' of F-rGO/EO is 26.7% higher than that of EO. Due to the stable structure for F-rGO, F-rGO/EO is self-extinguishing. The total heat release (THR) of F-rGO/EO-15 is 24.1 kJ/g, which is 5.6 kJ/g lower than that of EO.

Electromagnetic interference shielding performance of waterborne polyurethane composites filled with silver nanoparticles deposited on functionalized graphene

The objective of this study was to prepare an electromagnetic interference shielding material, waterborne polyurethane (WPU) filled with silver-nanoparticle-decorated functional reduced graphene oxide (Ag@FRGO). Functional reduced graphene oxide (FRGO) was functionalized through free-radical polymerization before chemical reduction, to prevent restacking and aggregation during the reduction. After the functionalization, the homogeneous dispersion of FRGO promoted the formation of conductive networks throughout the WPU matrix. To enhance the electrical conductivity and electromagnetic interference shielding effectiveness (EMI SE) of the composites, silver nanoparticles (Ag NPs) were deposited on the FRGO surface. Subsequently, WPU composites were synthesized through the solution-mixing method. Their microstructure, morphology, electrical conductivity, and EMI SE were investigated, and the results showed that, among Ag@FRGO/WPU composites with different values for the weight ratio of Ag NPs to FRGO, the Ag@FRGO/WPU composite with 5wt% FRGO and a weight ratio of Ag to NPs of 10:1 (10Ag@FRGO/WPU) exhibited the highest electrical conductivity (25.52S/m) and an EMI SE of 35dB in the frequency range of 8.2–12.4GHz (X-band).

Synthesis of reduced and functional graphene oxide with magnetic ionic liquid and its application as an electromagnetic-absorbing coating

The current study fabricated magnetic functional graphene oxide (MFGO) and magnetic functional reduced graphene oxide (MFRGO) by relying on FeCl4− magnetic anion confined to cationic 1-methyl imidazolium to absorb electromagnetic interference pollution. MFGO and MFRGO were characterized by X-ray photoelectron spectroscopy, Fourier transform infrared spectroscopy, X-ray diffraction, Raman spectroscopy, and field emission scanning electron microscopy. As a microwave-absorbing material, (MFGO)/epoxy resin composite was prepared using 10%–50% (wt) MFGO at thicknesses of 1–5 mm. The composites showed excellent microwave absorption in the microwave range of 8.0–12.0 GHz. The composite with 40% (wt) MFGO at 4 mm in thickness displayed several broad absorption bands. The strongest absorbing peak achieved a maximum absorption of −14.83 dB at 8.62 GHz and the maximum reflection loss was −25.21 dB at 8.62 GHz. When compared to with graphene oxide composites, both the MFGO and MFRGO composites exhibited significantly greater microwave absorption over the X band frequency range.