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Abstract: The Cu2O/SnO2/graphene (CSG) and SnO2/graphene (SG) nanocomposite photocatalysts were prepared by simple sol-gel growth method, and characterized by Fourier transform infrared spectra (FTIR), Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and Brunauer–Emmett–Teller (BET) measurements, respectively. The photocatalytic efficiency of catalysts were evaluated by degradation of pendimethalin under visible light irradiation (λ > 420 nm), which conformed that CSG and SG exhibited better photocatalytic activity than SnO2 or graphene alone. An effort has been made to correlate the photoelectro-chemical behavior of these samples to the rate of photocatalytic degradation of pendimethalin. The results demonstrated that the cuprous oxide addition into SG materials could greatly improve the photoelectric activity. The mechanism of photocatalytic reaction is proposed based on the energy band theory and experimental results. The CSG catalyst with higher photocatalytic activity may have great potential in various fields. [Copyright &y& Elsevier]

Abstract: Silver nanoparticles modified graphene-carbon nanotubes/polyimide (Gr-CNTs/PI) films have been prepared by electrochemical reduction of silver nitrate on potassium hydroxide hydroxylated of Gr-CNTs/PI films surface. The as-prepared nanocomposites were characterized by transmission electron microscopy, scanning electron microscopy, X-ray diffraction analyzer and semiconductor characterization system. The lower content of Gr-CNTs (≤10 wt. %) doping in PI matrix can improve the conductivity of PI films more clearly than pure CNTs. The conductivity can be regulated by controlling Gr-CNTs content in PI matrix. These silver nanoparticles into Gr-CNTs/PI films presented here can act as deposition seeds which can initiate subsequent electroless silver or copper or electrodeposition other metal. [Copyright &y& Elsevier]

A facile and green method was developed to synthesize the graphene–carbon nanotubes (Gr–CNTs) nanocomposite with a sandwich lamination structure. Pt nanoparticles were loaded on the as-synthesized Gr–CNTs nanocomposite to prepare an electrochemical sensor for determining bisphenol A (BPA) in thermal printing paper. The electrochemical behavior of BPA on the Pt/Gr–CNTs nanocomposite was investigated by cyclic voltammetry (CV) and chronocoulometry (CC). The direct determination of BPA was accomplished by using differential pulse voltammetry (DPV) under optimized conditions. The oxidation peak current was proportional to the BPA concentration in the range from 6.0 × 10−8 to 1.0 × 10−5 M and 1.0 × 10−5 to 8.0 × 10−5 M with a correlation coefficient of 0.987 and 0.998, respectively. The detection limit was 4.2 × 10−8 M (S/N = 3). The fabricated electrode showed good reproducibility, stability and selectivity. The proposed method was successfully applied to determine BPA in thermal printing papers samples and the results were satisfactory. [ABSTRACT FROM AUTHOR]

The electrocatalytic oxidation of ethanol is studied on the non-noble catalysts Ni-Co/graphene and Ni/graphene supported on glass carbon electrode (GCE) in alkaline medium. The synthesized materials are characterized by X-ray diffraction, X-ray photoelectron spectroscopy, transmission electron microscopy, and scanning transmission electron microscopy. The elements of Ni-Co/graphene and Ni/graphene catalysts are characterized using energy-dispersive X-ray spectroscopy. The electrocatalytic properties of Ni-Co/graphene and Ni/graphene for ethanol oxidation are investigated by cyclic voltammetry, chronoamperometry, and Tafel plot. Compared with Ni/graphene catalyst, Ni-Co/graphene has the higher electroactivity and better stability for ethanol oxidation. The rate constant ( k) and charge-transfer coefficient ( α) are calculated for the electron exchange reaction of the modified GCE. The results indicate that Co addition could promote the oxidation reaction at the Ni/graphene catalyst. Our study demonstrates that the low-cost electrocatalyst Ni-Co/graphene has a great potential for real direct ethanol fuel cells' application. [ABSTRACT FROM AUTHOR]

Abstract: Poly(l-arginine)/graphene composite film modified electrode was successfully prepared via a facile one-step electrochemical method and used for simultaneous determination of uric acid (UA), xanthine (XA) and hypoxanthine (HX). The electrochemical behaviors of UA, XA and HX at the modified electrode were studied by cyclic voltammetry and differential pulse voltammetry (DPV), and showed that the modified electrode exhibited excellent electrocatalytic activity toward the oxidation of the three compounds. The calibration curves for UA, XA and HX were obtained over the range of 0.10–10.0, 0.10–10.0 and 0.20–20.0μM by DPV, respectively and the detection limits for UA, XA and HX were 0.05, 0.05 and 0.10μM (S/N=3), respectively. With good selectivity and high sensitivity, the modified electrode has been applied to simultaneous determination of UA, XA and HX in human urine with satisfactory result. [Copyright &y& Elsevier]

Abstract: The sandwich lamination structure of graphene-multi-walled carbon nanotubes (Gr-CNTs) nanocomposite has been fabricated through in situ facile and green method. Then Pt nanoparticles are fabricated on Gr-CNTs via a simple one-step chemical reduction method in ethylene glycol (EG) and water system. The Gr-CNTs nanocomposite increased the solubility of carbon nanotubes in water, and CNTs could effectively prevent the irreversible aggregation of graphene. The Pt/Gr-CNTs were further characterized by scanning electron microscopy (SEM) and X-ray diffraction (XRD), which indicated that the as-synthesized Pt nanoparticles were successfully dispersed on the surface of Gr-CNTs nanocomposite. Electrochemical study has proved that the Pt/Gr-CNTs nanocomposite has higher catalytic activity in neutral medium for methanol oxidation, which is hopefully used in various types of cells and biosensors in physiological medium. [Copyright &y& Elsevier]

Abstract: A new facile in situ direct synthesis method of graphene–aniline (Gr–aniline) nanocomplex by a charge-transfer self-assembly technology at organic–aqueous interface was developed in this work. The graphene nanosheets can be dissolved in aniline without any prior chemical functionalization, and then Gr–aniline is soluble in a variety of organic solvents. The graphene–polyaniline (Gr–PANI) nanocomposite was prepared by simultaneous electropolymerization of Gr–aniline, and palladium nanoparticles were loaded onto the Gr–PANI nanocomposite to be used as a new electrode material for electrochemical sensing. Hydroquinone (HQ) and catechol (CC) were used as probe molecule to evaluate the electrocatalytic activity of Pd/Gr–PANI nanocomposite. The Pd/Gr–PANI nanocomposite shows so excellent electro-catalytic activities toward the oxidation of HQ and CC isomers that the oxidation peaks of the two molecules were well and easily resolved. The excellent reproducibility, stability and selectivity of the Pd/Gr–PANI nanocomposite make it a potential candidate as electrochemical sensor for simultaneous determination of HQ and CC isomers. [Copyright &y& Elsevier]

Abstract: Well-dispersed PtPdAu ternary alloy nanoparticles were synthesized on graphene sheets via a simple one-step chemical reduction method in ethylene glycol (EG) and water system, in which EG served as both reductive and dispersing agent. The electrocatalytic activity of PtPdAu/G was tested by methanol oxidation reaction (MOR). The catalyst was further characterized by transmission electron microscopy (TEM), energy dispersive X-ray spectroscopy (EDX), X-ray photoelectron spectroscopy (XPS) and X-ray diffraction (XRD), which indicated that the as-synthesized PtPdAu nanoparticles with alloy structures were successfully dispersed on the graphene sheets. Electrocatalytic properties of the catalyst for MOR in alkaline have been investigated by cyclic voltammetry (CV), chronoamperometry and Tafel curves. The electrocatalytic activity and stability of PtPdAu/G were superior to PtPd/G, PtAu/G and Pt/G. In addition, the anodic peak current on PtPdAu/G catalyst was proportional to the concentration of methanol in the range of 0.05–1.00M. This study implies that the prepared catalyst have great potential applications in fuel cells. [Copyright &y& Elsevier]