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Abstract: A novel electrochemical sensor for chlorophenols was fabricated by using the Pd-graphene nanocomposite and ions liquid. The Pd-graphene nanocomposite was prepared via a sonoelectrochemical route, and the possible formation mechanism was proposed. Transmission electron microscopy, scanning electron microscopy, X-ray diffraction and Raman spectrum were used for the characterization of structure and morphology of the nanocomposite. The experimental results showed that Pd nanospheres comprised of small Pd nanoparticles were uniformly attached on graphene sheets. The electrocatalytic properties were investigated by cyclic voltammetry (CV) and differential pulse voltammetry (DPV), which indicated that the Pd-graphene nanocomposite had high activity for chlorophenol oxidation. Herein, 2-chlorophenol was selected as the model molecules. The results showed that graphene played an important role in the fabrication of the chlorophenols sensor. The nanocomposite with large electrochemical active surface led to the excellent electrocatalytic activity, and ionic liquid further enhanced the catalytic activity of Pd-graphene for chlorophenols. [Copyright &y& Elsevier]

Abstract: Acidic and neutral Nafion® 115 perfluorosulphonate membranes have been modified by in situ polymerization of pyrrole using Fe(III) and H2O2 as oxidizing agents, in order to decrease methanol crossover in direct methanol fuel cells. Improved selectivities for proton over methanol transport and improved fuel cell performances were only obtained with membranes that were modified while in the acid form. Use of Fe(III) as the oxidizing agent can produce a large decrease in methanol crossover, but causes polypyrrole deposition on the surface of the membrane. This increases the resistance of the membrane, and leads to poor fuel cell performances due to poor bonding with the electrodes. Surface polypyrrole deposition can be minimized, and surface polypyrrole can be removed, by using H2O2. The use of Nafion in its tetrabutylammonium form leads to very low methanol permeabilities, and appears to offer potential for manipulating the location of polypyrrole within the Nafion structure. [Copyright &y& Elsevier]

Abstract: The Cu2ZnSnS4 (CZTS) thin films with uniform and porous surface feature with the pore size of 100-200nm were successfully prepared by pyrolysis procedure using the methanol solution containing copper chloride dihydrate (0.06mol dm−3), zinc chloride (0.03mol dm−3), stannous chloride dihydrate (0.03mol dm−3), thiourea (0.48mol dm−3) and deionized water (1.92mol dm−3) as precursor solution at 380°C in air atmosphere. Electrochemical impedance spectroscopy was applied to evaluate the electrochemical catalytic activity of the pyrolysis CZTS thin films for redox couple of Sn 2-/S2− and the charge transfer resistance was 64.08Ω using the pyrolysis CZTS thin film obtained by repeating the procedure of dipping the FTO substrate into the precursor solution and heating at 380°C for 7 cycles. The assembled quantum dot-sensitized solar cells gave an open-circuit photovoltage of 0.52V, a short-circuit photocurrent density of 12.96mAcm−2, and a fill factor of 0.38, corresponding to the photoelectric conversion efficiency of 2.56%. Because the pyrolysis procedure was a facile, low cost and vacuum-free process, and had the advantage of obtaining various porous microstructure thin films and allowing deposition over large areas, the pyrolysis CZTS thin films can serve as an effective counter electrode for QDSCs. [Copyright &y& Elsevier]

Abstract: Three-dimensional (3D) porous V2O5 and Fe0.1V2O5.15 thin films have been prepared by electrostatic spray deposition technique. X-ray diffraction, scanning electron microscopy and X-ray photoelectron spectroscopy are employed to investigate the structures and valence states of the films. Galvanostatic cell cycling, cyclic voltammetry and impedance spectroscopy are used to characterize their electrochemical properties. The Fe0.1V2O5.15 thin film shows much better cycling performance than the non-doped V2O5 thin film. Fe3+ can act as a stabilizing agent in the layered V2O5 and increase the reversibility of the charge and discharge processes towards deeper depth of lithium insertion/extraction. The dissolution of the active material in the electrolyte can also be significantly suppressed in the Fe-doped sample. Nevertheless, the Fe-doping causes a slight decrease in lithium ion diffusion coefficient. [Copyright &y& Elsevier]

Abstract: Poly(diallyldimethylammonium chloride) functionalized helical carbon nanotubes (PDDA-HCNTs) were successfully synthesized. The resulting PDDA-HCNTs composite has good conductivity, solubility and ferromagnetic property. The fabricated HCNTs could be conveniently separated and magnetically attached to the magnetic electrode owing to their excellent magnetic properties. An amperometric biosensor was firstly developed based on glucose oxidase (GOD) functionalized PDDA-HCNTs loaded on magnetic glass carbon electrode. The constructed biosensor exhibited excellent electrocatalytic activity and stability for the detection of glucose with a linear range from 5 to 85μM and a low detection limit of 0.72μM at 3σ. The present work offers a new avenue to broaden the applications of HCNTs in electrochemical biosensors. [Copyright &y& Elsevier]