Graphene Oxide Hybrid Materials Research Articles

Influence of Concentration and Electrodeposition Time on the Electrochemical Supercapacitor Performance of Poly(3,4-Ethylenedioxythiophene)/Graphene Oxide Hybrid Material

Poly(3,4-ethylenedioxythiophene)/graphene oxide (PEDOT/GO) composites with wrinkled paper-like sheets morphology were electropolymerized potentiostatically at 1.2 V with different electrodeposition times (1–30 min) and various concentrations of GO (0.5, 1.0, 1.5, and 2.0 mg/mL). The electrochemical properties of PEDOT/GO composites as an electrode material for supercapacitor were investigated using cyclic voltammetry, electrochemical impedance spectroscopy (EIS), and galvanostatic charge-discharge (GCD). The CV results revealed that PEDOT/GO containing 1.0 mg/mL GO and electropolymerized for 10 minutes exhibited the highest specific capacitance (157.17 F/g). This optimum PEDOT/GO was found to have energy and power density of 18.24 W/kg and 496.64 Wh/kg, respectively, at 1.0 A/g current density. The resistance of charge transfer obtained for PEDOT/GO is very low (13.10 Ω) compared to PEDOT (638.98 Ω), proving that PEDOT/GO has a good supercapacitive performance due to the synergistic effect of the high conductivity of PEDOT and large surface area of GO.

Green and rapid synthesis of a water-dispersible Pt–reduced graphene oxide hybrid material for hydrogen peroxide detection

A kind of water-dispersible Pt nanoparticle–reduced graphene oxide hybrid material (Pt–rGO) has been prepared by in situ reduction of both graphene oxide (GO) and the Pt precursor in acidic solution using metallic Zn powder.

Radiation-induced graft copolymerization of dimethylaminoethyl methacrylate onto graphene oxide for Cr(VI) removal

Dimethylaminoethyl methacrylate (DMAEMA)-grafted graphene oxide hybrid materials (GO-g-P) were fabricated using γ-ray irradiation at ambient temperature. The morphology and structure of GO-g-P were characterized by Fourier-transform infrared spectroscopy (FT-IR), X-ray photoelectron (XPS), thermogravimetric analysis (TGA) and X-ray diffraction (XRD). It was confirmed that DMAEMA was grafted successfully on the surface of graphene sheet. The grafting yield of GO-g-P increased with monomer concentration (0–2.5molL−1) and dose (0–40kGy). The resulting adsorbent (GO-g-P) with amine groups was highly efficient for removing Cr(VI) from its acidic aqueous solution and could be easily separated by filtration. The optimum pH for Cr(VI) removal was observed at pH 1.1 and the Cr(VI) uptake of GO-g-P at this pH was 82.4mgg−1.

Synthesis of A3B zinc tetrapyrazinoporphyrazine covalently functionalized reduced graphene oxide

In this Letter, a novel strategy was applied to the preparation of tetrapyrazinoporphyrazine–reduced graphene oxide hybrid material. Reduced graphene oxide was functionalized with carboxylic acid groups via diazotization with 4-aminio benzoic acid and subsequent amidation with the synthesized aminoalkyl-tetrapyrazinoporphyrazine. FT-IR, Raman, TGA, UV–vis, and fluorescence spectrophotometry methods were utilized for characterization of the hybrid material, which exhibited an electron/energy transfer ability.

Sol–gel synthesis of palladium nanoparticles supported on reduced graphene oxide: an active electrocatalyst for hydrogen evolution reaction

In this work, the synthesis and characterization of palladium nanoparticle-reduced graphene oxide hybrid (Pd–rGO) material is reported. Techniques of X-ray diffraction, transmission electron microscope (TEM), energy-dispersive X-ray, FT-IR spectroscopy, thermogravimetric analysis and cyclic voltammetry were used to characterize the structure and properties of the Pd–rGO. Results demonstrate the effect of Pd on the reduced GO. The average particle size of the Pd nanoparticles supported on rGO obtained from TEM is about 12–18 nm. Moreover, glassy carbon electrode (GCE) modified with palladium nanoparticle–graphene oxide hybrid (Pd–rGO/GCE) was prepared by casting of the Pd–rGO solution on GCE. The electrochemical and catalytic activity of the Pd–rGO/GCE was studied in 0.1 M H2SO4 solution. The Pd–rGO/GCE electrode exhibited remarkable electrocatalytic activity for the hydrogen evolution reaction (HER). At potential more negative than −0.4 V vs. Ag |AgCl |KCl3M, the current is mainly due to hydrogen evolution reaction. Finally, the kinetic parameters of hydrogen evolution reaction are also discussed on the Pd–rGO/GCE.

Robust fluorescence sensing platform for detection of CD44 cells based on graphene oxide/gold nanoparticles

Gold-coated graphene oxide hybrid material (GO/AuNPs) has exceptional physical and chemical properties like π–π stacking interaction and plays a role in quencher of fluorescence dye. Therefore, GO/AuNPs could enhance the signal-to-background ratio with fluorescence dye that was the point in this fluorescent biosensor. In this study, tetramethyl-6-carboxy-rhodamine (TAMRA)-labeled aptamers that specifically interact with the hyaluronic acid binding domain of CD44 were used as targets to investigate the applicability of the method. GO/AuNPs–TAMRA-aptamer complexes could detect CD44 target cancer cells within a concentration range of 1×101 to 1×107 CFU/mL. A linear relationship was observed between target cell concentration and relative fluorescence intensity. The more mounted up CD44 target cell concentrations, relative fluorescence intensity of GO/AuNPs–TAMRA-aptamer complexes was increased even more, which was superior to that of GO alone. Sensitivity of the detection system displayed a low detection limit of 1×101 CFU/mL. Additionally, this method is specific in that fluorescence is not much enhanced in CD44 negative cancer cell line. Thus, the fluorescence sensing based on GO/AuNPs could be developed to receptive and robust detection tool for various target molecules.

Nanostructured polystyrene/polyaniline/graphene hybrid materials for electrochemical supercapacitor and Na-ion battery applications

In this work, nanostructured polystyrene/polyaniline/reduced graphene oxide (PS–PANI/rGO) hybrid materials based on in situ reduction of graphene oxide with ascorbic acid and self-assembly have been successfully prepared for electrochemical supercapacitor and Na-ion battery applications. The supercapacitor based on the PS–PANI/rGO as an electrode material exhibits a specific capacitance of 180 F g−1 at a current density of 0.5 A g−1 from −0.4 to 1.0 V and a high energy density of 49 W h kg−1 at the power density of 352.8 W kg−1. Moreover, the nanostructured PS–PANI/rGO has a good cycle stability (74 % capacitance retention after 5000 cycles), indicating its future potential application in electrochemical energy storage. The material is further used as an anode in Na-ion batteries, and the results show that the porous nanostructured PS–PANI/rGO delivers a high capacity of 155 mA h g−1 and keeps over 150 charge–discharge cycles at a constant current of 100 mA g−1 (0.5 C).

Efficient charge transfer in solution-processed PbS quantum dot–reduced graphene oxide hybrid materials

We developed a general approach to couple silane-functionalized rGO with colloidal semiconductor nanocrystals, which show efficient and tunable charge transfer.

Production of novel FeOOH/reduced graphene oxide hybrids and their performance as oxygen reduction reaction catalysts

Fe-based hybrid systems have been suggested as promising candidates for oxygen reduction reaction (ORR) catalysts owing to their good catalytic performances and feasibilities for mass production at low cost. In this work, we develop means of producing novel hybrids containing FeOOH particles well-dispersed on graphene-based materials using a one-pot solution process. The hybrid materials show good electrochemical catalytic activity for ORR, such as, an on-set potential of 0.76V (vs. the reversible hydrogen electrode), a near four electron pathway, and excellent stability against methanol poisoning during durability test. This is the first report of the use of FeOOH/reduced graphene oxide hybrid materials as ORR catalysts.

One-pot hydrothermal synthesis of mesoporous Zn(x)Cd(1-x)S/reduced graphene oxide hybrid material and its enhanced photocatalytic activity.

We successfully synthesized mesoporous Zn(x)Cd(1-x)S/reduced graphene oxide (Z(x)CSG) hybrid materials as photocatalysts using a facile one-pot hydrothermal reaction, in which graphene oxide (GO) was easily reduced (RGO), and simultaneously Zn(x)Cd(1-x)S (Z(x)CS) nanoparticles (NPs) with a mesoporous structure were uniformly dispersed on the RGO sheets. By well tuning the band gap from 3.42 to 2.21 eV by changing the molar ratio of Zn/Cd (or Zn content), Z(x)CSG with an optimal zinc content has been found to have a significant absorption in the visible light (VL) region. In addition, under VL irradiation (λ > 420 nm), Z(x)CSG also showed zinc content-dependent photocatalytic efficiencies for the degradation of methylene blue (MB). Our findings are that, among Z(x)CSG, Z(0.4)CSG displayed not only a superior photodegradation efficiency of MB (98%), but also good removal efficiency of total organic carbon (TOC) (67%). Furthermore, Z(0.4)CSG had a high photocatalytic stability, and could be used repeatedly. The enhanced photocatalytic activity for Z(0.4)CSG could be attributed to a synergistic effect between mesoporous Z(x)CS NPs and RGO, including the optimal band gap and the moderate conduction band position for ZxCS (compared to CdS), efficient separation and transfer ability of photogenerated electron/hole pairs in the presence of RGO sheets, and relatively high surface area for both mesoporous Z(x)CS NPs and RGO.

Facile electrochemical synthesis of polydopamine-incorporated graphene oxide/PEDOT hybrid thin films for pseudocapacitive behaviors

We report facile synthesis of polydopamine-functionalized graphene oxide/conducting polymer hybrids as an electrode material for supercapacitors. Bio-inspired polydopamine has catechol moieties that can undergo redox transformation, which may result in extra faradic capacitance. Polydopamine-functionalized graphene oxide hybrid materials, which were easily prepared by concomitant dopamine oxidation and slight reduction of graphene oxide, showed enhanced specific capacitance when compared to bare graphene oxide hybrid materials. Although polydopamine layers slightly decreased the conductivity of the hybrid materials, extra redox reactions appeared to contribute more to the overall specific capacitance.

Synthesis and nonlinear optical properties of reduced graphene oxide hybrid material covalently functionalized with zinc phthalocyanine

A reduced graphene oxide–zinc phthalocyanine (RGO–ZnPc) hybrid material with good dispersibility has been prepared by covalent functionalization method, based on the initial covalent linkage of ZnPc to GO and subsequent in situ reduction of GO moiety to RGO during mild thermal treatment in DMF solvent. The microscopic structure, morphology and photophysical properties of resultant RGO–ZnPc hybrid are characterized. The nonlinear optical (NLO) properties of the RGO–ZnPc hybrid are also investigated using the Z-scan technique at 532nm with 4ns laser pulses. The results show that the efficient functionalization and reduction of GO make RGO–ZnPc hybrid possess much larger NLO properties and optical limiting performance than those of individual GO, ZnPc and the GO–ZnPc hybrid. It can be ascribed to a combination of different NLO absorption mechanisms for RGO–ZnPc hybrid, including two-photon absorption originating from the sp3 domains, saturable absorption from the sp2 carbon clusters and excited state absorption from numerous localized sp2 configurations in RGO moiety, reverse saturable absorption arising from ZnPc moiety and the contribution of efficient photo-induced electron transfer or energy transfer process between ZnPc and RGO.

Tungsten oxide nanowires grown on graphene oxide sheets as high-performance electrochromic material

In this work, we report the synthesis of a novel hybrid electrochromic composite through nucleation and growth of ultrathin tungsten oxide nanowires on graphene oxide sheets using a facile solvothermal route. The competition between the growth of tungsten oxide nanowires and the reduction of graphene oxide sheets leads to the formation of sandwich-structured tungsten oxide-reduced graphene oxide composite. Due to the strongly coupled effect between the ultrathin tungsten oxide nanowires and the reduced graphene oxide nanosheets, the novel electrochromic composite exhibited high-quality electrochromic performance with fast color-switching speed, good cyclic stability, and high coloration efficiency. The present tungsten oxide-reduced graphene oxide composite represents a new approach to prepare other inorganic-reduced graphene oxide hybrid materials for electrochemical applications.

One-step combustion synthesis of NiFe2O4-reduced graphene oxide hybrid materials for photodegradation of methylene blue

NiFe 2 O 4-reduced graphene oxide (RGO) hybrid materials (NFRGs) were synthesized by a simple one-step combustion method. The structures, morphologies and magnetic properties were characterized by X-ray diffraction, transmission electron microscopy, Fourier transform infrared spectroscopy, Raman spectroscopy, and vibrating sample magnetometer analysis. The results show that graphene oxide sheets are not oxidized, but reduced to RGO. The superparamagnetic behavior of NFRGs was observed. The as-synthesized magnetically separable NFRGs show improved photodegradation performance when compared to neat NiFe 2 O 4, attributed to the narrowing band gap, the efficient transfer of photo-generated electron from NiFe 2 O 4 to RGO sheets, and the improved adsorptive property of photocatalyst due to the high specific surface area of RGO sheets.

Structural Changes in Reduced Graphene Oxide upon MnO2 Deposition by the Redox Reaction between Carbon and Permanganate Ions

We explore structural changes of the carbon in MnO2/reduced graphene oxide (RGO) hybrid materials prepared by the direct redox reaction between carbon and permanganate ions (MnO4–) to reach better understanding for the effects of carbon corrosion on carbon loss and its bonding nature during the hybrid material synthesis. In particular, we carried out near-edge X-ray absorption fine structure spectroscopy at the C K-edge (284.2 eV) to show the changes in the electronic structure of RGO. Significantly, the redox reaction between carbon and MnO4– causes both quantitative carbon loss and electronic structural changes upon MnO2 deposition. Such disruptions of carbon bonding have a detrimental effect on the initial electrical properties of the RGO and thus lead to a significant decrease in electrical conductivity. Electrochemical measurements of the MnO2/reduced graphene oxide hybrid materials using a cavity microelectrode revealed unfavorable electrochemical properties that were mainly due to the poor electric...

Synthesis, characterization and photocatalytic properties of MIL-53(Fe)–graphene hybrid materials

MIL-53(Fe)–reduced graphene oxide (rGO) hybrid materials with different rGO contents were prepared through a simple one-step solvothermal method. The products were characterized by X-ray diffraction patterns, thermal analysis, FT-IR spectra, Raman spectroscopy, scanning electron microscopy, UV-vis absorption spectra and photoluminescence spectra. The hybrid with 2.5% rGO content showed optimal photocatalytic performance in degradation of methylene blue under both UV and visible light irradiation and the degradation rate constants under UV and visible light were 1.34 and 1.57 times of those using MIL-53(Fe) respectively. The considerable promotion in photoactivities can be attributed to rGO being able to separate the photogenerated electrons and suppress electron–hole recombination. In addition, the hybrids show increased light absorption intensity and range. This work provides a new concept that MOF–rGO hybrids can be used as high performance photocatalysts and applied in the field of environmental protection.

Porous Co3O4 Nanorods–Reduced Graphene Oxide with Intrinsic Peroxidase-Like Activity and Catalysis in the Degradation of Methylene Blue

A facile two step process was developed for the synthesis of porous Co3O4 nanorods-reduced graphene oxide (PCNG) hybrid materials based on the hydrothermal treatment cobalt acetate tetrahydrate and graphene oxide in a glycerol-water mixed solvent, followed by annealing the intermediate of reduced graphene oxide-supported Co(CO3)0.5(OH)·0.11H2O nanorods in a N2 atmosphere. The morphology and microstructure of the composites were examined by X-ray diffraction, X-ray photoelectron spectroscopy, transmission electron microscopy and Raman spectroscopy. It is shown that the obtained PCNG have intrinsic peroxidase-like activity. The PCNG are utilized for the catalytic degradation of methylene blue. The good catalytic performance of the composites could be attributed to the synergy between the functions of porous Co3O4 nanorods and reduced graphene oxide.

Facile synthesis of graphene oxide hybrids bridged by copper ions for increased conductivity

In this article, we report a facile method for preparing graphene oxide (GO) hybrid materials consisting of copper ions (Cu2+) complexed with GO, where Cu2+ acted as bridges connecting GO sheets. The method of film formation is based on cross-linking GO using Cu2+ followed by filtration onto nanoporous supports. This binding can be rationalized due to the chemical interaction between the functional groups on GO and the metal ion. We observed that there was a decrease in charge transfer resistance through electrochemical study. It suggests that the presence of metal ions in GO films could introduce new energy levels along the electron transport pathway and open up possible conduction channels. We also found that the hybrid graphene film assembled with Cu2+ dramatically decreases resistance through flash light reduction.

Transition-metal nitride nanoparticles embedded in N-doped reduced graphene oxide: superior synergistic electrocatalytic materials for the counter electrodes of dye-sensitized solar cells

Transition-metal nitride TMN (MoN, TiN, VN) nanoparticle–N-doped reduced graphene oxide (NG) hybrid materials are presented as alternative low-cost platinum-free counter electrodes for dye-sensitized solar cells (DSCs). A high concentration of active catalytic sites and an efficient electronic/ionic mixed conducting network generated by the nanostructure afford promising synergistic effects on the electrocatalytic characteristics for triiodide reduction. On the basis of these advantages, these nanostructured hybrid based cells deliver significantly enhanced photovoltaic performances. The efficiencies of devices employing VN–NG, TiN–NG and MoN–NG are 6.279%, 7.498% and 7.913% respectively, which are comparable with that of Pt devices (7.858%). Such a design strategy is facile, cost effective and versatile, thus it may be extended to other inexpensive platinum-free counter electrode materials.

UV light assisted synthesis of ternary reduced graphene oxide hybrid materials and their photocatalytic performance

Freely-assembled ternary hybrids consisting of Pt, reduced graphene oxide (RGO) and P25 were synthesized by a direct solution process with the assistance of UV light. The Pt-RGO/P25 hybrids were characterized by Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), field emission scanning electron microscopy (SEM), transmission electron microscopy (TEM), ultraviolet visible (UV-vis) diffuse reflectance spectroscopy (DRS) and photoluminescence spectra (PL). Importantly, when Pt-RGO/P25 hybrids were used as photocatalysts, they could show a superior photocatalytic performance when compared to commercial P25 and RGO/P25 hybrids under UV, solar light and λ > 600 nm visible light irradiation, which could be explained on the basis of the plasmonic response and the formation of Pt Schottky barrier at the interface between TiO2 and graphene. This work could provide new insight for enhancing graphene/TiO2 photocatalytic performance and facilitate their application in environmental protection.