Electrochemical properties of diamond-like carbon electrodes prepared by the pulsed laser deposition method

Diamond-like carbon electrodes (DLCEs) have been synthesized by the pulsed laser deposition method. The surface structure of the DLCEs has been studied by atomic force microscopy and the root-mean-square roughness has been established as R _ms≥81 ?. Electrochemical impedance spectroscopy and cyclic voltammetry data show that DLCEs are nearly ideally polarizable in the potential region –0.4<E<1.1 V (vs. Ag|AgCl|sat. KCl in H₂O) in 0.1 M NaF+H₂O solution. Various equivalent circuits have been used for fitting the complex plane and Bode plots. A very good agreement between experimental and calculated Nyquist curves has been established if the charge transfer and double layer charging at the surface, intercalation of the H⁺ and (or) Na⁺ ions and solid phase diffusion inside the nanoparticle, as well as the effect of an insulating film at the surface (i.e. surrounding the nanoparticles), are taken into account.     

Synthesis and gas-sensing properties of phenylhydrazine-functionalized single wall carbon nanotubes in polymer matrix

Gas sensor material was prepared by encapsulation of functionalized single-walled carbon nanotubes (SWCNT) into a gas-permeable polymer poly(1-trimethylsilyl-1-propyne) (PTMSP). A phenylhydrazino group was used for the functionalization of SWCNTs to improve their solubility and compatibility with polymers. Syntheses were carried out in aqueous surfactant solutions and in pure phenylhydrazine without surfactant. Two different temperatures (24 and 50°C) and two surfactants (sodium dodecyl sulfate and tricaprylmethylammonium chloride — Aliquat®336) were compared. Functionalized SWCNTs were characterized by X-ray photoelectron (XPS), Raman and Fourier transform infrared (FTIR) spectroscopy. Analyses showed that the synthesis at higher temperature in pure phenylhydrazine resulted in the highest functionalization yield. Phenylhydrazine itself proved to be a good solvent for SWCNTs. The functionalized nanotubes were soluble in organic solvents that under the same conditions were appropriate solvents for polymers. The sensitivity of functionalized SWCNT-PTMSP thin film composite to NO₂ gas at room temperature was significantly higher than that of the similar sensor material containing the pristine SWCNTs.