Mehmet Levent Aksu

Electroreduction of nitrobenzene to p-aminophenol using voltammetric and semipilot scale preparative electrolysis techniques

This paper describes an investigation of the reduction of nitrobenzene to p-aminophenol by the use of CV, RDE and preparative electrolysis with Cu and Cu(Hg) electrodes. The preparative electrolyses of nitrobenzene were carried out at controlled current and controlled potential conditions using copper and amalgamated copper using a new semipilot (laboratory) scale system in the absence of an organic cosolvent. The effects of redox reagents and the concentration of nitrobenzene in catholyte added to the medium were also examined. The best results were obtained with 2.3% BiCl3 at nitrobenzene concentration of 0.144 g cm−3 catholyte. The most suitable electrode material was found to be amalgamated copper and the reduction of nitrobenzene to p-aminophenol was found to follow an ECE mechanism.

Electrochemical properties of polythiophene depending on preparation conditions

Abstract In this study, electrochemical properties of thiophene and polythiophene (PT) were investigated in tetrabutyl ammoniumperchlorate (Bt4NP), tetraethyl ammoniumtetrafluoroborate (Et4NBF4) and tetrabutyl ammoniumhexafluorophosphate (Bt4NPF6) supporting electrolytes in acetonitrile. Polarization curves and in situ conductance measurements show that PT films have different electrochemical properties and conductance values according to the type and concentration of the supporting electrolyte employed. In addition, the oxidation time, the potential and applied current were found to have a significant influence on the conductance values of the final polymers. A suitable mechanism is proposed.

Preparation and Characterization of PVA/Boron Polymer Produced by an Electrospinning Technique.

Abstract In this study, poly(vinyl alcohol) were cross-linked with boron in varying concentrations and blend fibers were obtained with diameters ranging from 0.3 μ to 4.0 μm with the use of electrospinning process. The resulting product was characterized by SEM, DSC, and FT-IR techniques. There is no beading tendency in either boron doped or undoped fibers. When the amount of boric acid in PVA solutions was increased the conductivity of the polymer decreased. The data indicated the existence of boron oxide in the polymeric structure and the formation of B-O-C bond. SEM micrographs reveal that higher viscosity favors the formation of thicker fibers. Boron addition seems to disturb the easy detachment of the fibers from the tip of the Taylor Cone

Preparation and Characterization of PVA/Zinc Acetate/ Boron Composite Fibers

Abstract The objective of this work was to synthesize boron incorporated PVA/Zinc acetate nano precursor composite polymer fibers using electrospinning technique. Produced fibers, are useful reagents in organic synthesis of zinc oxide nano structures which have gained wide interest because of their potential applications in the fabrication of microelectronic devices. Boron incorporated PVA/Zinc acetate not only improve the electrical properties of ZnO films but also has an influence on the crystal structure of ZnO films. The fibers were measured and characterized by conductiometer (with four-point probe), Fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). The formation of boron incorporated PVA/Zinc acetate hybrid polymer was confirmed by FT-IR spectra. SEM micrographs clearly reveal that there are random-growth oriented fibers on aluminum foil with diameters ranging from 0.5 to 1 μm. According to the TGA analysis decomposition of zinc acetate from the PVA chain was observed around 273 °C, 368 °C and 447 °C. Boron incorporated PVA/Zinc acetate nano composite polymer fibers have been successfully synthesized for the first time using electrospinning technique and characterized in detail as precursor material for ZnO. Electrospinning process has been a widely used, simple and versatile method and in future may be used for large-scale preparation of nanofibers of ZnO.

Cathodic reduction of 4-nitroso-N,N-dimethylaniline at various electrode materials

This study is concerned with the cathodic reduction of 4-nitroso-N,N-dimethylaniline to 4-amino-N,N-dimethylaniline in 1.0 M HCl and 1.0 M H2SO4 containing 10% MeOH. The effect of cathode material, supporting electrolyte, electroactive compound concentration, temperature and current density in the electrochemical synthesis of 4-amino-N,N-dimethylaniline were investigated. The best cathode material was tin, which gave a selectivity of 92.7% with a current yield of 90.3% at a current density of 6 mA cm−2. The final electrolysis product was obtained as its respective HCl and H2SO4 salts and their structures were elucidated using spectrochemical techniques.

Thermoelectric Properties of Nickel and Boron Co-Substituted NaCo2O4 Prepared by Electrospinning Technique

In this study nickel and boron doped sodium cobalt oxide NaCo2-xNixByO4 (0≤x≤0.3, 0≤y≤0.1) nanocrystalline thermoelectric ceramic powders were synthesized using electrospinning techniques and then consolidated into bulk ceramics. The differences in the microstructure and thermoelectric properties of the samples as a result of doping effect have been investigated. The crystalline structures of the powders and nanofibers were characterized using X-ray diffraction and scanning electron microscopy and BET Analysis before and after the calcination process at different temperatures. Nanofibers prepared by the use of electrospinning technique, have a diameter of approximately 300 nm, and the diameter of the grains of calcined powders was observed to range between 150 to 500 nanometers. Thermoelectric properties of the bulk ceramics were measured by physical properties measurement system (Lot-Oriel PPMS) in a temperature range of 15–300 K. The calculated values of dimensionless figure of merit at 300 K are 4.25×10-5, 5.3×10-6, 8.6×10-5 and 9×10-6 for sintered powders from undoped, Ni and B doped powders, respectively.