Incorporation Of Reduced Graphene Oxide Research Articles

A Simple Preparation Method of Reduced Graphene Oxide‐Incorporated BiVO4 Loaded with CoOx Composites and Application to Z‐Schematic Water Splitting under Visible Light Irradiation

The construction of Z‐scheme systems is an efficient strategy to realize water splitting under visible light irradiation. In particular, various photocatalysts can be employed for Z‐scheme systems when a reduced graphene oxide (RGO) is used as an electron mediator. Herein, a simple 1‐step process for the preparation of RGO‐(CoOx/BiVO4) composites is developed. In the developed preparation method, Co ions are oxidized to CoOx by photogenerated holes in BiVO4 accompanied by simultaneous reduction of GO to RGO by photoexcited electrons. The developed preparation method is simpler than a conventional method that contains loading with CoOx by impregnation and subsequent incorporation of RGO by photocatalytic reduction. Z‐schematic water splitting under visible light irradiation proceeds when RGO‐(CoOx/BiVO4) prepared by the 1‐step process is combined with Pt/(CuGa)0.5ZnS2. Moreover, the developed method is also able to be applied to the preparation of RGO‐(FeOx/BiVO4) composites.

Reduced graphene oxide (RGO) reinforced Mg biocomposites for use as orthopedic applications: Mechanical properties, cytocompatibility and antibacterial activity

Magnesium (Mg) has attracted wide interest in orthopedic applications as they exhibit great biodegradability and strong biocompatibility, while corrosion is the main concern for Mg that should be addressed prior to biomedical applications. In this work, ZM31 (Mg-3Zn-1Mn)/xRGO ( x = 0, 0.5, 1 and 1.5 wt%) biocomposites were synthesized by semi-powder metallurgy method. The results showed that the RGO acting as an effective reinforcing filler to prevent deformation and showed better compressive strength (282.3 ± 9 MPa) and revealed enhancement in failure Strain (7.8 ± 2.1%) at 1 wt% RGO concentration compared to Mg alloy (244.5 ± 9 MPa and 7.1 ± 1.5% respectively). Moreover, fracture analysis indicated a more ductile fracture of the nanocomposites after the incorporation of RGO. Crack bridging, crack deflection and crack branching are dominant mechanisms for reinforcement of Mg-based containing RGO. Mg composites containing 0.5 wt% RGO showed a low corrosion rate (2.75 mm/year), while more incorporation of RGO resulted in an increased corrosion rate (4.38 mm/year). In addition, the degradation rate of ZM31 alloy (2.57 mg.cm − 2 .d −1 ) obviously decreased with the addition of 0.5 wt% RGO (1.84 mg.cm − 2 .d −1 ) in the SBF. Besides, continuous apatite layers were created on the composites in the SBF solution. Also, the cell culture examinations showed good cell viability and adhesion on composites with 0.5 and 1 wt% RGO, which was demonstrated by the SEM and MTT assay The alkaline phosphatase (ALP) activity of the ZM3–0.5RGO composite was considerably higher than that of ZM31 matrix alloy in 24 h and 48 h, implying higher osteoblastic differentiation. The antibacterial behavior toward both bacteria ( E. coli and S. aureus ) exhibited that escalating RGO concentration in Mg-matrix composites leads to further inhibition of bacteria growth. These findings suggested that ZM31–0.5RGO biocomposite could be a more promising candidate for orthopedic implants.

Preparation and evaluation of nanocomposites based on transitional oxides and carbon materials for electrochemical applications

In the present paper, it was studied the possibility of obtaining nickel oxide (NiO) for developing nanocomposites based on transitional oxides and carbon materials for electrochemical applications. In order to obtain nanostructured NiO, the precipitation method was chosen and the influence of surfactants (e.g. SDS, CTAB, PEG, IGEPAL CA-630 and hydroxypropyl cellulose) on the structural and morphological properties of NiO was established. The oxide precursor was treated at a maximum of 700 °C. The used carbon material is reduced graphene oxide (RGO) and was obtained by the Hummer's method. The ex-situ method was used for obtaining nanocomposites, consisting of the formation of a homogeneous mixture between the fillers (RGO and NiO) and the polymeric matrix polyvinylidene fluoride (PVDF). The influence of filler concentration on the electroactive β-phase of PVDF was evaluated. The developed materials were analyzed from a morphological and structural point of view and the wetting capacity was determined, using characterization techniques, such as FTIR and EDX spectroscopy, X-ray diffraction, SEM microscopy and goniometry. The morphological study shows the synthesis of oxide particles with dimensions below 80 nm, their insertion in the graphene domains and close interaction between composite components took place. Structural studies indicate crystalline purity of the oxide and increased electroactive β phase nucleation by the incorporation of RGO and NiO into the PVDF matrix. The PVDF-RGO-NiO composite has a hydrophilic character. The ability of PVDF-RGO-NiO nanocomposites to store charge was evaluated via cyclic voltammetry.

Preparation and identification of a biocompatible polymer composite: Shielding against the interference of electromagnetic waves

Hybrid composites containing Cu nanostructures (NSs), reduced graphene oxide (RGO), and polystyrene (PS) were produced for electromagnetic shielding application. First, Cu NSs including nanoparticles (NPs), nanorods (NRs), and nanowires (NWs) were prepared by a green method using eucalyptus bark extract from the reaction of copper(II) chloride in ethylene glycol (EG) at 186 °C. The FE-SEM images, XRD patterns, and Raman spectroscopy were used to characterize these NSs. The RGO/PS composite was prepared by introducing RGO to the PS matrix. The tensile test revealed that by adding 10% of RGO to the PS matrix, the tensile strength of the RGO/PS composite increased by 13.8%. The thermal properties of the RGO/PS composite indicated that with the uniform incorporation of RGO on the PS matrix, the thermal stability of the polymer composite was elevated to 350 °C and the Tg to 112 °C. Conductive polymer nanocomposites (PNCs) were prepared by adding Cu NSs to the RGO/PS composite. The results showed that these PNCs had electromagnetic interference (EMI) shielding; the shielding effectiveness of PNCs containing 10% RGO and 25% Cu NWs was 36.0 dB at 8.0 GHz and 29.5 dB at 12.0 GHz. The predominant mechanism of protection in the frequency range and percentages of the filler under study was of the reflection type.

Impact of the reduced graphene oxide (RGO) on the ageing kinetics of Al-Mg-Si alloy with different grain sizes

We fabricated 0.4 wt.% reduced graphene oxide (RGO)-reinforced microlaminated Al-Mg-Si composite with two different grain sizes (layer thicknesses) of approximately 1 μm and 2 μm. It was found that the thinner layer, the more significant the RGO incorporation accelerated the ageing kinetics. The peak-aged RGO-Al composite with ∼1 μm lamellae thickness had considerably higher mechanical strength and uniform elongation, as compared to their unreinforced counterpart and the composite with ∼2 μm lamellae thickness. Such a strength-ductility synergy was likely to come from a combined effect of the refined grain size and the facilitated dislocation storage in the matrix grains.

Simultaneous electrodeposition of electrochemically reduced graphene oxide-binary metal chalcogenide composites to enhance photoelectrochemical performance

In this study, a facile and one-step simultaneous electrodeposition of the composite thin films bearing binary metal chalcogenides (CdxZn1-xS (x = 0.0, 0.2, 0.5, 0.8, 1.0)) and electrochemically reduced graphene oxide (RGO) was carried out via repetitive cyclic voltammetry (rCV). Then their photoelectrochemical (PEC) performances were investigated under the solar light irradiation to find out the optimized composition of the composites. Immobilization of Cd1-xZnxS nanoparticles among the RGO sheet with the rCV confined the Cd1-xZnxS nanoparticles between the RGO sheets, which prevented leakage of these particles from the electrode surface and contributed to the increase of active sites for the PEC reaction. PEC results showed that increasing x from 0 to 0.8 in CdxZn1-xS composition boosted the photocurrent density, reaching from 25 μA cm−2 to 438 μA cm−2. Incorporation of RGO to the structure increased the conductivity and prevented the photocorrosion of Cd0.8Zn0.2S, thus, RGO(0.25)-Cd0.8Zn0.2S enhanced the photocurrent density from 0.44 mA cm−2 (as-synthesized Cd0.8Zn0.2S) to 1.38 mA cm−2.

Strength-conductivity synergy in cold-drawn reduced graphene oxide (RGO)-aluminum composite wires for electrical applications

We present a breakthrough of the strength-conductivity trade-off in cold wire drawn reduced graphene oxide (RGO)-aluminum (Al) composite. The composite was fabricated by a full glovebox powder metallurgy process, followed by hot rolling and wire drawing down to 0.5 mm wire diameter. Compared to the unreinforced Al fabricated by the same methodology, the incorporation of RGO in the 0.5 mm wire sample gave rise to approximately 20.7% improvement in mechanical strength, with only ~3.6% sacrifice in electrical conductivity. Furthermore, the 331.6 ± 6.8 MPa compressive strength and ~54.1%International Annealed Copper Standard (IACS) of the 0.5 mm wire RGO-Al composite exhibited a strength-conductivity combination comparable or even superior to conventional Al alloy conductors that go through complex thermal-mechanical treatments. Such a property synergy was interpreted by the ultra-fine Al grain structure and the elongated grain morphology rendered by the deformation processing steps, and an Orowan-typed strengthening mechanism owing to the homogenously dispersed natural amorphous alumina and RGO nanosheets in the composite.

Investigation of plasmon-induced extraction efficiency enhancement in a CdTe-based LED using FDTD simulation.

Light-emitting diodes (LED) based on silicon platforms and CdTe quantum dots (QDs) are an important area of research. Due to poor charge balance in QD layers, reduced graphene oxide (RGO) was introduced between the P-Si substrate and CdTe QDs. To further improve the performance of the QDs-LED, Au nanorods (NRs) were incorporated into the hole transport layer. A finite-difference time-domain simulation was used to discuss theoretically the influence of RGO and Au NRs on the LED performance, and investigate the influence of substrate on the localized surface plasmon resonance (LSPR) coupling wavelength. Simulated results demonstrated that the LSPR peaks for Au NRs red shifted with increase in substrate refractive index, and the electric field along the x-y plane was mostly concentrated near the interface. RGO incorporation enhanced the emission of the QDs-LED. This may be attributed to improvement in conductivity and hole mobility in the hole transport layer and reduction in the energy barrier for injection of holes. After introduction of Au NRs, there was a significant enhancement in emission, and light extraction efficiency was enhanced about 10-fold.

A novel H2O2photoelectrochemical sensor based on ternary RGO/Ag-TiO2 nanotube arrays nanocomposite

Ternary nanocomposite photoelectrodes composed of Ag nanoparticles, reduced graphene oxide (RGO), and TiO2 nanotube arrays (TNTs) were successfully designed and achieved by a combining technique of cyclic voltammetry and anodic oxidation. Herein, the obtained RGO/Ag-TNTs composites were employed for photoelectrochemical (PEC) monitoring platform of hydrogen peroxide (H2O2) for the first time. Compared to pure TNTs, Ag-TNTs, and RGO-TNTs, the ternary RGO/Ag-TNTs nanocomposites with appropriate loading amount of RGO and Ag show much higher PEC activity, which were contributed to the synergistic effect resulting from the effective incorporation of Ag nanoparticles and RGO onto the TNTs to accelerate the electron transfer, increase the charge carrier density and prolong the electron lifetime demonstrated by electrochemical impedance spectroscopy (EIS), Mott-Schottky (M-S) measurements and open circuit voltage decay (OCVD) measurement. Under the optimal experimental conditions, the as-prepared PEC sensors exhibited an extremely wide dynamic range from 10−7 nM to 10 mM, and in the range of 0.1–10 mM with higher sensitivity and a detection limit of 20 μM. Moreover, the PEC sensors displayed good reproducibility, long-term stability, and selectivity toward the determination of H2O2. These excellent results make the as-developed ternary RGO/Ag-TNTs nanocomposites a promising candidate in PEC detection H2O2.

Fabrication of graphene/gelatin/chitosan/tricalcium phosphate 3D printed scaffolds for bone tissue regeneration applications

The scaffold structures formed by the incorporation of reduced graphene oxide (RGO) nanomaterials can be studied to improve the 3D matrix properties in the applications of bone regeneration. On the other hand, RGO has delayed the incorporation into the mixtures that were determined to generate scaffolds on using 3D printing because of its poor colloidal stability of particles and weak solubility in water. Moreover, to produce RGO, the graphene oxide (GO) was treated with hydrazine hydrate solution, which was well known as a reducing agent that is highly hazardous. To outcome these drawbacks, an unique eco-friendly method was established to gather scaffolds that were 3D printed by the incorporation of RGO. This was obtained using the Gallic acid induced in situ reduction of the GO already existing on the gelatin/chitosan/tricalcium phosphate scaffolds. Moreover, scaffolds also exhibited antibacterial activity without conceding osteoblasts’ cell proliferation and viability. Furthermore, the obtained scaffolds showed good osteoblasts proliferation and viability indicating their possibility for applications in bone fracture healing.

Effect of filler loading on the shielding of electromagnetic interference of reduced graphene oxide reinforced polypropylene nanocomposites prepared via a twin-screw extruder

Thermoplastic polypropylene (PP) with different loadings (0.5, 1, 3 & 5 wt%) of reduced graphene oxide (RGO) were prepared to design a nanocomposite to shield the electromagnetic interference (EMI) using melt processing technique via a twin-screw extruder. The nanocomposites were characterized by dc conductivity, mechanical, fractography, and electromagnetic shielding applications. Incorporation of RGO significantly affects the mechanical strength of nanocomposites, which helps to rise in the tensile (4.7%) and flexural strength (4%) at maximum (5 wt%) RGO loading compared to pure PP. There has an improvement in the electrical conductivity of nanocomposites with an increase in the filler load. The RGO/PP nanocomposites exhibit the EMI shielding effectiveness (SE) of − 10.2 dB with 2 mm of thickness at 5 wt% of RGO loading. The outcomes showed that the RGO/PP nanocomposites are able to block up to 90% of the EM wave and are a potential candidate for another kind of microwave absorbing material at large-scale manufacturing division.

Investigation of improvement in stability and power conversion efficiency of organic solar cells fabricated by incorporating carbon nanostructures in device architecture

Carbon nanotubes (CNTs) along with reduced graphene oxide (RGO) are synthesized using modest methods and their composites with the polymers PEDOT:PSS and P3HT are prepared using an easy solution method. An attractive improvement in the composites’ physical properties with wt% increase of the filler material is observed, encouraging their applications in the fabrication of organic solar cells (OSCs). Using the composites in appropriate layers of the device architecture, OSCs have been fabricated by spin coating, and the incorporation of filler CNTs and RGO has been observed to result in considerable improvement in the power conversion efficiency (PCE) of all OSCs. To study the stability of the devices, the electrical properties of the OSCs have been periodically investigated in two different environments to understand the impact of both intrinsic and extrinsic degradation. The incorporation of filler carbon nanomaterials has been noticed to be successful in significantly prolonging the stability of the OSCs while maintaining the augmentation in PCE. For the best performing devices, the incorporation of CNTs and RGO has enhanced the PCE by 12.52% and 13.21% and improved the device lifetime by 37.31% and 43.23%, respectively, compared to the reference device. The results discussed in this report are greatly promising for the large scale consideration of a pioneering role of organic materials in numerous optoelectronic devices from a new and innovative perception assisted by the application of carbon-based nanomaterials.

One-step fabrication of Ag/RGO doped TiO2 nanotubes during anodization process with high photocatalytic performance

Reduced graphene oxide (RGO) and Ag nanoparticles were incorporated simultaneously with two-step anodic TiO2 nanotube through anodization process, and their photocatalytic activity was investigated in the degradation of 2,4-dichlorophenol (2,4-DCP). Furthermore, the optical properties and photocatalytic degradation efficiency were examined as a function of Ag NPs concentration in Ag/RGO–TiO2 nanotube. Morphological characterization showed that Ag NPs and RGO sheets were well-doped inside and outside the TiO2 nanotubes’ walls. Meanwhile, X-ray diffraction and EDX analysis confirmed the existence of both Ag NPs and RGO. The optical investigation revealed that the incorporation of Ag NPs and RGO with TiO2 nanotubes improved the light absorbance and the narrowing of TNT bandgap energy (from 2.85 to 2.35 eV). Therefore, among the various samples, Ag50/RGO–TNTs photocatalyst had the most optimal performance, degrading 96% and 66% of 2,4-DCP under UV and visible light irradiation, respectively. The kinetic study confirmed that degradation reactions over all photocatalysts followed zero-order kinetics. Finally, the recovery test of the optimum sample (Ag50/RGO–TNT) showed 6% reduction following 5-cycle photocatalytic degradation of 2,4-DCP under UV irradiation.

Synergistic effect of RGO/TiO2 nanosheets with exposed (0 0 1) facets for boosting visible light photocatalytic activity

This study reports a simple strategy of fabricating reduced graphene oxide (RGO) /TiO2 with high-energy (0 0 1) facets. TiO2 nanosheets (TiO2 NST) are grown in situ on RGO via a one-step solvothermal method, forming RGO-supported TiO2 nanosheet (RGO/TiO2 NST). The significance of the (0 0 1) facets and RGO being integrated is also discussed in this work. The incorporation of RGO widens the absorption of visible light and accelerates the transport of carriers. TiO2 NST constructs the band gap width at a relatively narrow level in the growth with RGO, contributing to a high carrier yield and an enhanced separation efficiency. The synergy can efficiently stimulate the separation and inhibit the recombination of electron-hole pairs. The synthesised RGO/TiO2 NST with 2 wt% RGO can almost completely eliminate methyl orange within 180 min under visible-light, which is 30 times more efficient than TiO2 nanoparticles; further, the NST does not undergo any evident change even after 5 consecutive cycles. The mineralisation rate of up to 94.08% for MO can also be regarded as an indicator of a high-efficiency catalyst. Comprehensively, the synthesis of the samples with outstanding properties obtained herein can readily expand the application prospects that are associated with environmental energy and electrochemical devices.

Preparation of Reduced Graphene Oxide (RGO) Modified Titanium Dioxide Nanotube (TNTs) as Visible Light Effective Catalyst for the Conversion of CO2 to CH4

In this study, a modified visible light active photocatalyst has been prepared where titanium dioxide nanotube (TNTs) was coupled with reduced graphene oxide (RGO) through a facile synthesis process. The photoactivity of the RGO-TNTs has been evaluated by converting CO2 to CH4 under visible light irradiation. In order to justify the photo-effectivity of the catalysts, physical and optical characterization were performed through FESEM, EDX, UV-Vis absorption spectra and PL spectra. The morphological analysis shows homogeneous RGO distribution on the TiO2 nanotube whereas elemental compositional analysis revealed the presence of all elements in the prepared catalyst. Visible light enhancement activity of the prepared catalyst after the incorporation of RGO was exposed by UV-Vis analysis due to its enhanced light absorption properties. Improved electron-hole separation rate was investigated for the RGO incorporated TNTs through PL analysis. The fruitful incorporation of the RGO with TNTs further affirmed by the increased photocatalytic activity by converting CO2 to CH4 that acquired enhanced CH4 production (9.27%) which is 1.81 times higher than the CH4 production rate obtained through TNTs (5.12%). Thus, this study induces a simple synthesis procedure to modify TNTs as a visible light active photocatalyst with the integration of RGO. Moreover, RGO-TNTs enhanced visible light activity were evaluated through the conversion of CO2 to CH4.

Excellent photoresponse performances of graphene/metallic WSe2 nanosheet heterostructure films

The metallic (1T) structure of transition metal dichalcogenides is of many peculiar chemical and physical properties such as higher carrier mobility and narrower bandgap compared to 2H structure and so maybe beneficial in their photodetection application. Currently, efficient assembly of 1T-WSe2 in the one-step process is still an enormous challenge. Here we report a modified facile hydrothermal approach assembling 1T-WSe2 nanosheets and 1T-WSe2/reduced graphene oxide (RGO) hybrids. The photodetector based on the assembled 1T-WSe2 nanosheets showed very high photocurrent and extremely intense and fast light responses. The RGO incorporation introduced a remarkable charge transfer at the heterojunction interface and further dramatically heightened the photocurrent and light responsivity.

Preparation and characterization of RGO-incorporated hypercross-linked polymers for CO2 capture

The growing demand for nano-structured composite materials and sustainable processes for next generation CO2 capture technologies has necessitated the need to develop novel and cost-effective synthetic routes for solid CO2 adsorbents based on hypercross-linked polymers (HCPs) and reduced graphene oxide (RGO) microporous sorbent materials with improved physico-chemical properties. The most important selection is modification of the synthesized microporous sorbent materials by the incorporation of RGO, giving rise to composite materials that combine the properties of both. These hybrid materials will be of great potential for carbon capture and storage (CCS) applications, especially for post-combustion CO2 capture, owing to the increase in CO2 capturing efficiency and selectivity to CO2 compared to other flue gases. Herein, we report a facile and effective approach for fabrication of HCPs-supported reduced graphene oxide composites. The microporous HCPs was synthesized using 4,4′-bis(chloromethyl)-1,1′-biphenyl monomer by Friedel–Crafts alkylation. The RGO was prepared by modified Hammers method. The as-synthesized composites were characterized by TEM, SEM, FTIR, TGA and N2 adsorption–desorption isotherm. The HCP/RGO composite showed maximum CO2 adsorption of 5.1 wt% than the HCPs alone at 40 °C and 1 atm.

Enhanced Electrochemical performance at high temperature of Cobalt Oxide/Reduced Graphene Oxide Nanocomposites and its application in lithium-ion batteries

We report a microwave irradiation method for the preparation of reduced graphene oxide (RGO) based Co3O4 nanocomposites as anodes for lithium-ion (li-ion) batteries. The Co3O4/RGO nanocomposites displayed good electrochemical behavior as anodic materials for li-ion batteries when compared to pure Co3O4. The Co3O4/RGO nanocomposites with low RGO content resulted in stable electrochemical performance with 100% coulombic efficiency at a high current density of 500 mA/g for 50 cycles. The enhanced capacity of the Co3O4/RGO nanocomposites is due to the incorporation of RGO, which resulted in a four times larger surface area than that of Co3O4. This increased surface area could facilitate the absorption of more lithium ions, resulting in excellent electrochemical performance. Interestingly, the novelty of this work is that the designed li-ion batteries showed stable electrochemical performance even at a high temperature of 100 °C, which might be useful for rechargeable battery applications in a wide temperature range.

Reduced graphene oxide/metallic MoSe2: Cu nanosheet nanostructures grown by a chemical process for highly efficient water splitting

The transition metal dichalcogenides with metallic 1T structure are attracting contemporary attention for applications in high-performance devices because of their peculiar optical and electrical properties. To date, one-step synthesis of 1T-MoSe2 is a challenge. This work presents a facile one-step synthesis of reduced graphene oxide/1T MoSe2: Cu nanosheets. The experiment results indicated that the MoSe2 prepared by simple chemical solution reaction possessed 1T structures. The reduced graphene oxide (RGO) incorporation and Cu doping did not obviously affect the phase structure but decreased the average particle size. The 1T structure, together with the Cu doping and interface effect between the MoSe2 and RGO, remarkably enhanced the conduction and photoconduction of the nanostructures. Thus, Cu doping and RGO incorporation also enhanced the hydrogen evolution catalytic activity and stability, making the RGO/MoS2: Cu nanosheet a most active and stable catalyst for hydrogen evolution.

The Influence of Space Restriction on the Mechanical Properties of Isotactic Polypropylene/Reduced Graphene Oxide Nanocomposite Injection Bars

Isotactic polypropylene (iPP)/reduced graphene oxide (RGO) nanocomposite bars were prepared by injection molding and the effects of RGO on the iPP matrix were investigated via differential scanning calorimetry, two dimensional wide angle X-ray diffraction (2D WAXD) and small angle X-ray scattering (2D SAXS) techniques. It is demonstrated that RGO is an effective nucleation agent for iPP and the incorporation of RGO can enhance the degree of orientation of iPP crystals at flow direction. Furthermore, the orientation of iPP chains at flow direction intensifies with the increase of RGO contents, which can be attributed to that RGO obstructed the motion of orientated polymer chains. Although the enhancement effect is weaker than that of High density polyethylene (HDPE)/RGO nanocomposites with epitaxial crystallization, the mechanical properties of iPP/RGO nanocomposites can also be improved apparently.