Mass Ratio Of Graphene Research Articles

Facile synthesis of ternary heterojunction Bi2O3/reduced graphene oxide/TiO2 composite with boosted visible-light photocatalytic activity

In this work, a novel ternary heterojunction composite with bismuth oxide (Bi2O3), titanium dioxide (TiO2) and reduced graphene oxide (rGO) was produced via a one-step hydrothermal process. The prepared Bi2O3/rGO/TiO2 (BRGT) composite possessed a strong visible-light responsiveness and a high separation efficiency of photogenerated carriers, with a specific surface area of 133.1 m2/g. The optimal degradation performance towards tetracycline (94.3% removal) was obtained by BRGT-10 with Bi/Ti molar ratio of 10% and mass ratio of graphene oxide/Ti of 5% following conditions of 0.1 g/L BRGT-10 at pH of 6.7. The degradation rate of tetracycline by BRGT was 4.5, 3.8, 1.4, and 1.28 times that of TiO2, TiO2/rGO, Bi2O3/TiO2, and Bi2O3/TiO2@rGO, respectively. O2− radicals and holes play the dominant roles in the photodegradation of tetracycline. Based on density function theory calculation and liquid chromatography-mass spectrometry identification of intermediates, the degradation pathways of tetracycline were mostly attributed to the breakage of carbon-carbon double bonds, nitrogen-carbon bonds and rearrangement of hydroxyl groups, and the decreased toxicity of the formed intermediates was evaluated. The BRGT-10 composite owned optimal reusability and applicability. This study explores a facile synthesis process of ternary heterojunction composite and provides insights into photodegradation mechanism of refractory organics from water under visible-light.

Preparation and Thermal Conductivity of Epoxy Resin/Graphene-Fe3O4 Composites.

By modifying the bonding of graphene (GR) and Fe3O4, a stable structure of GR-Fe3O4, namely magnetic GR, was obtained. Under the induction of a magnetic field, it can be orientated in an epoxy resin (EP) matrix, thus preparing EP/GR-Fe3O4 composites. The effects of the content of GR and the degree of orientation on the thermal conductivity of the composites were investigated, and the most suitable Fe3O4 load on GR was obtained. When the mass ratio of GR and Fe3O4 was 2:1, the thermal conductivity could be increased by 54.8% compared with that of pure EP. Meanwhile, EP/GR-Fe3O4 composites had a better thermal stability, dynamic thermomechanical properties, and excellent electrical insulation properties, which can meet the requirements of electronic packaging materials.

Epoxy-matrix polyaniline/p-phenylenediamine-functionalised graphene oxide coatings with dual anti-corrosion and anti-fouling performance.

This research work reports on the anti-corrosion and anti-fouling properties of epoxy (E) coatings reinforced with polyaniline (PANI)/p-phenylenediamine-functionalised graphene oxide (PGO) composites. The mass ratio of graphene oxide/p-phenylenediamine in any PGO was assumed to be 1 : 1, but different PANI–PGO composites containing various loadings of PGO were prepared. An ultrasonic-assisted in situ polymerization method was employed to produce PANI–PGO at low temperature (0 °C). Several analytical and microscopical techniques, i.e., Fourier-transfer infrared (FTIR) spectroscopy, X-ray diffraction (XRD), and field emission scanning electron microscopy (FESEM), were used to confirm that PANI–PGO composites were successfully synthesized. The epoxy-based coatings (E/PANI–PGO (x), x = 0.05–0.4 g) were applied by brushing them onto carbon steel substrates, which exhibited dual anti-corrosion and anti-fouling performance. Electrochemical impedance spectroscopy (EIS) results show that E/PANI–PGO (0.2) has the highest corrosion resistance (8.87 × 106 Ω cm2) after 192 h of immersion in 3.5 wt% NaCl amongst all the coatings compared with neat epoxy (1.00 × 104 Ω cm2) and E/PANI (6.82 × 103 Ω cm2). Efficient antifouling performance at the macroscopic level under simulated marine conditions was observed for the epoxy-based PANI–PGO coatings with a range of PGO compositions, in particular for the 0.1 and 0.2 g PGO coatings.

Synergistic effect of functionalized graphene/boron nitride on the thermal conductivity of polystyrene composites

Polymeric composites with enhanced thermal conductivity (TC) have great applications in thermal management materials. Herein, we reported a synergistic effect of functionalized graphene (GR) and boron nitride (BN) on the thermal conductivity (TC) of polymeric composites. Here, functionalized GR and BN were prepared by modified Hummers' method and liquid exfoliation method, respectively. The polystyrene (PS) composites were obtained via solution blending followed by hot-pressing method. The results demonstrated that the TC of the PS composites increased with the synergistic effect of functionalized GR and BN. When the mass ratio of graphene oxide/hydroxylated boron nitride (GO/BN-OH) was 7:3, the TC of the composites reached maximum and exhibited the highest TC enhancement up to 20%, but less than synergistic improvement of the TC of GR/BN with same filler loading and the TC enhancement about 21.5%. The study indicated that the oxygen-containing groups on the two dimensional thermal conducting fillers were not conducive to the increase of heat conduction.

Construction and Application of nanocellulose/graphene/MnO2 three-dimensional composites as potential electrode materials for supercapacitors

The research on graphene–nanocellulose-based electrodes in supercapacitors has attracted more and more attention. We have innovatively prepared a carbon–biomass–metal oxide ternary aerogel electrode using a green hydrothermal method, successfully combining a graphene–nanocellulose–manganese dioxide electrode (MCGA) by loading MnO2 metal particles into a three-dimensional porous aerogel composed of graphene and nanocellulose. It is found that when the mass ratio of graphene, nanocellulose and MnO2 is 1:1:4, the obtained aerogel electrode MCGA1:1:4 shows the best electrochemical performance. The MCGA1:1:4 electrode exhibits a high specific capacitance of 212.73 F g−1 at 5 mV s−1 and extreme stability of 86.5% capacitance retention ratio after 5000 cycles at 2 A g−1. This ternary hybrid electrode based on biomass, carbon and metal oxides may become a trend in the development of high-performance supercapacitors.

Assembly of graphene on Ag3PO4/AgI for effective degradation of carbamazepine under Visible-light irradiation: Mechanism and degradation pathways

A highly efficient visible-light-driven photocatalyst Ag3PO4/AgI-Graphene (Ag3PO4/AgI-G) was synthesized through a chemical coprecipitation procedure. Scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS) were performed to study the physicochemical structural of the photocatalysts. The photocatalytic activity of the samples was examined by the carbamazepine (CBZ) degradation under artificial visible light and natural sunlight irradiation. Experimental results indicated that the introduction of low mass content of graphene enhanced the photocatalytic performance of Ag3PO4/AgI, and the photocatalytic degradation efficiency of CBZ over Ag3PO4/AgI-3%G (mass ratio of graphene:Ag3PO4/AgI = 3:100) reached 93.06% within 21 min, which was much higher than that over pure Ag3PO4 (26.92%) and Ag3PO4/AgI (74.38%). UV–vis diffuse reflectance spectra, photoluminescence (PL) spectra, transient photocurrent responses and electrochemical impedance spectra (EIS) of the samples were conducted to verify the high photocatalytic performance of the Ag3PO4/AgI-3%G. In addition, possible photocatalytic degradation pathways of CBZ were proposed based on the analysis of transformation products during the reaction. The reactive species trapping experiments and Electron spin resonance (ESR) analysis demonstrated that h+ and O2− were the main active oxidant species responsible for CBZ photodegradation. The photocatalytic degradation mechanism of CBZ over Ag3PO4/AgI-3%G under visible light irradiation was schematically proposed. This study not only provides a new technique for the synthesis of Ag3PO4-based photocatalysts with high photocatalytic activity, but also demonstrates that the Ag3PO4/AgI-3%G composite could be a promising photocatalyst for the treatment of waters containing CBZ.

Preparation and photocatalytic properties of KH-550 modified nano-TiO2/graphene Composites.

KH-550 modified nano-TiO2/RGO composites were synthesized via a one-step hydrothermal method to improve the photocatalytic activity of nano-TiO2.The composites were characterized by X-ray Diffraction (XRD), Scanning Electron Microscope (SEM), Transmission Electron Microscope (TEM), Raman spectra, X-ray Photoelectron Spectroscopy (XPS). In addition, methyl orange solution was used in optical degradation to investigate the photocatalytic properties. The results showed that the photocatalytic degradation rate of KH-550 modified nano-TiO2/RGO composites was 57.32% while pure nano-TiO2, nano-TiO2/RGO was only degraded 28.83%, 46.68% during the same time and same mass ratio. Compared with nano- TiO2, the photocatalytic degradation rate of nano-TiO2/RGO and KH-550 modified nano-TiO2/ RGO composites were improved by 17.85%, 28.49% respectively. However, the composites displayed the best photocatalytic performance when the mass ratio of graphene and KH-550 modified nano-TiO2 was 8%.

Manganese Oxides Supported on TiO2–Graphene Nanocomposite Catalysts for Selective Catalytic Reduction of NOX with NH3 at Low Temperature

TiO2–graphene (TiO2–GE) nanocomposites were prepared by the sol–gel method with different mass ratios of graphene (0–2% wt %). With the MnOX active component loaded by means of ultrasonic impregnation, the catalysts exhibited excellent structure and electrical properties, which favored the catalytic reaction. All the catalysts were characterized by XRD, SEM, TEM, BET, FT-IR, XPS, and Raman spectroscopy. The results indicated that the reduction of graphene oxide and formation of graphene in TiO2–GE supports and TiO2–graphene were readily indexed to anatase TiO2 in all samples. Various valences of manganese species coexisted in MnOX/TiO2–GE catalysts. Especially, nonstoichiometric MnOX/Mn on the surface of composite catalyst was beneficial to the electron transfer; therefore, the redox performance of the catalyst was improved. The MnOX/TiO2–0.8%GE catalyst exhibited good resistance to simultaneous H2O and SO2, as well as to only H2O, with an optimum Mn mass ratio of 7 wt %. All the samples showed excellent ...

Hydrothermal synthesis of graphene/nickel oxide nanocomposites used as the electrode for supercapacitors.

Graphene (GR)-based nanocomposites with different mass ratios of NiO and GR are prepared via hydrothermal method using Ni(NO3)2 as the origin of nickel and urea as the hydrolysis-controlling agent. The morphology and electrochemical performance of the GR/NiO nanocomposites are closely associated with the mass ratios of GR to NiO. The chemical composition and morphology of the composites together with the pure GR and NiO are characterized by thermogravimetric analysis (TGA), X-ray diffraction (XRD), scanning electron microscope (SEM), and transmission electron microscope (TEM). It is found that the GR sheets and NiO particles form uniform nanocomposites with the NiO particles absorbed on the GR surface. A specific capacitance of 384 F g(-1) at a current density of 0.1 A g(-1) is achieved when the coating amount of NiO is up to 74 wt%. In addition, the attenuation of the specific capacitance is less than 6% after 500 cycles, indicating such nanocomposite has excellent cycling performance.

Preparation, photocatalytic activity, and mechanism of Cd2Sb2O6.8-graphene composite

Novel nanocomposite materials, based on graphene (GR) and Cd2Sb2O6.8, were synthesized successfully through a facial one-step hydrothermal method for the first time. Characterized by X-ray diffraction, UV–vis diffuse reflectance spectroscopy, transmission electron microscopy, field emission scanning electron microscopy (FESEM), Fourier-transform infrared spectroscopy, Raman spectroscopy, etc., it demonstrated that Cd2Sb2O6.8 nanoparticles were effectively anchored in GR sheets. By the degradation of rhodamine B (RhB) and methylene blue, such Cd2Sb2O6.8-GR nanocomposites exhibited a much higher photocatalytic activity than the pure Cd2Sb2O6.8. Especially, when the mass ratio of GR in Cd2Sb2O6.8-GR nanocomposite was 2% (labeled as Cd2Sb2O6.8-2%GR), it possessed the optimal photocatalytic ability on the degradation of RhB which was as high as that of commercial P25. It was proved that GR played an important role in the enhancement of photocatalytic performance of composites. Which give a good chance to make an effective charge separation and generation of multifarious reactive species, such as OH, O2−, h+, e−. A possible mechanism of the degradation process was carefully discussed. This work provided a new insight into the photocatalytic degradation of dyes under UV irradiation and opens up a new prospect to Cd2Sb2O6.8-GR photocatalysts.

Preparation of sulfonated graphene–polyaniline nanofiber composites by oil/water interfacial polymerization and their application for supercapacitors

An easy and one-pot method for the preparation of sulfonated graphene–polyaniline nanofiber (SGEPA) composites by oil/water interfacial polymerization was studied in this work. Among the composites were obtained at different mass ratios of graphene and aniline. The chemical structure of the materials was characterized by Fourier transform infrared spectroscopy and X-ray diffraction. The morphology of the material was studied by scanning electron microscope and high resolution transmission electron microscopy. The SGEPA composite electrodes with a mass ratio of 1:10 showed better electrochemical performance than pure polyaniline nanofiber and graphene. A high specific capacitance of 962F/g was obtained at a potential scan rate of 2mV/s and the specific capacitance value of SGEPA-110 retained about 78% after 1000 cycles. It also exhibited a high energy density of 68.86Wh/kg at a power density of 102W/kg. The extraordinary electrochemical properties of the composites were attributed to the well-designed structural advantages of binary nanocomposites and the good combination and synergistic effects between graphene and polyaniline.

One-pot synthesis of graphene/In2S3 nanoparticle composites for stable rechargeable lithium ion battery

Graphene/In2S3 nanoparticle composites were synthesized by an easy and scalable hydrothermal method without any surfactant, strong reducing agent or highly toxic hydrazine. Graphene oxide acts as a scaffold for growth of In2S3 nanoparticles and was simultaneously reduced to graphene in the growth process of In2S3 nanoparticles. The composites with different mass ratios of graphene were used as anodes in rechargeable lithium ion batteries. Transmission electron microscopy characterization and impedance measurement verified that graphene can act as a buffering layer to accommodate the volume change of In2S3 and facilitate the charge-transfer process. The battery with graphene/In2S3 nanoparticle composites anode showed a remarkable Li-storage performance with a better cycling life and higher capability than that of the pure In2S3. The graphene/In2S3 nanoparticle composites retain a high discharge capacity of ∼1000 mA h g−1 after 200 cycles at a current density of 0.1 A g−1. Investigation on the changes in morphology, phase, and microstructure of the graphene/In2S3 nanoparticle composite upon cycling indicate that the incorporation of graphene with In2S3 can optimize the morphology and phase stability of In2S3. It is believed that the scalable preparation process and the respectable electrochemical performance would pave the way for practical application.