Showing papers by "Hiroshi Nishihara published in 1987"

Synthesis of ferrocene and cobaltocene electrode films by electropolymerization and their spectral and electrochemical properties

Abstract: Electroreduction in acetonitrile solutions of Fe(C/sub 5/H/sub 4/CH/sub 2/Cl)/sub 2/ (1), Fe(C/sub 5/H/sub 4/CCl=CHCHO)/sub 2/ (2), Fe(C/sub 5/H/sub 5/)(C/sub 5/H/sub 4/CCl=CHCHO) (3), and (Co(C/sub 5/H/sub 4/CCl=CHCHO)/sub 2/)PF/sub 6/ (4) led to deposition of stable electroactive films on glass-carbon and indium tin oxide coated glass electrodes. Structure and characteristics of these films were investigated by FT-IR and UV-visible spectroscopy, scanning electron microscopy, and film thickness measurements. The volume concentrations of ferrocene sites and electroactive sites in the polymer (Fe(C/sub 5/H/sub 4/CH/sub 2/-)/sub 2/)/sub n/ formed from 2 mM solution of 1 were estimated at 7.5 x 10/sup -3/ and 3.8 x 10/sup -4/ mol/cm/sup 3/, respectively. Scanning electron microscopy revealed a heterogeneity, probably coexistence of the electroactive and inactive sites, in the films formed from 1 and 4. Cyclic voltammetry or organic redox solutes such as nitrobenzenes or benzoquinones at the electrodes coated with the ferrocene polymers from 1-3 indicated that these polymers can control the reversibility of the redox reactions of the solutes.

AC Impedance Studies on Relationship between Adsorption Behavior of Polar Organic Compounds on Anodically Polarized Nickel and the HSAB Principle

Abstract: It has been confirmed by impedance and polarization measurements that the adsorption behavior of polar organic compounds on anodically polarized nickel electrode in are closely related to the HSAB principle. The compounds used as corrosion inhibitors were those of which polar atoms were elements of the 5B and 6B groups in the periodic table. Double layer capacity of the electrode‐solution interface in the active region of the polarization curve showed that the compound classified as a soft base was more readily chemisorbed on the surface acting as a soft acid than that of a hard base. Hence, inhibition efficiency of a soft base inhibitor for nickel dissolution was higher than that of a hard base inhibitor. In the passive region, compounds classified as hard bases lowered the passive current density of the electrode, while some soft bases stimulated it. These results are discussed with respect to the HSAB principle by using the impedance data in the passive region.

Adsorption and Corrosion Inhibition Effect of Anions Plus an Organic Cation on Iron in 1M HClO4 and the HSAB Principle

Abstract: Influence de neuf anions et du cation organique (ion tetra-n-butylammonium) sur la vitesse de corrosion d'une electrode de fer dans une solution 1M HClO 4 . Adsorption des ions sur l'electrode

Electrochemical synthesis of poly(p-phenylene vinylene) films

Abstract: Electroreduction of α,α,α′,α′-tetrabromo-p-xylene at an indium tin oxide (ITO), platinum, copper or nickel electrode in ethereal solution afforded a thick and uniform poly(p-phenylene vinylene) film in the undoped state. Addition of Cr(CO)6 or Mo(CO)6 accelerated the film growth at the ITO electrode.

The Synergistic Effect of Anions and the Ammonium Cation on the Inhibition of Iron Corrosion in Acid Solution

Abstract: The synergistic effect of various anions and the tetra- n -butylammonium cation on the inhibition of iron corrosion in 1 M HClO 4 and their joint adsorption on iron were studied by using an impedance and a polarization technique. Surface coverage obtained from double layer capacitance showed joint adsorption of the anion and cation on the iron surface. Assuming competitive adsorption of these ions at the interface, the synergism of corrosion inhibition and joint adsorption were estimated using a parameter calculated from the inhibition efficiencies and the surface coverages of the anion and/or cation. The synergistic effect was shown for all of the anions and cation examined.

Electrochemical Synthesis of Poly(p-phenylene xylylidene), a New Electrically Conducting Polymer

Abstract: Electroreduction of α,α,α,α′,α′,α′-hexachloro-p-xylene at a copper electrode in n-Bu4NBF4-propylene carbonate gave a free-standing film of poly(p-phenylene xylylidene), PPX, a new conducting polymer with phenylenic and acetylenic backbones. The PPX film exhibited a conductivity of 70 S cm−1 on doping with SO3.

A chemical diode by combination of ferrocene and cobalticinium electrode films

Abstract: Current vs. voltage curves of a device comprising ITO/Poly-Cc+BF4–/Poly-Fc/ITO {where ITO, Poly-Cc+BF4–, and Poly-Fc are In–Sn oxide, a polymer formed by electrochemical reduction of [Co(C5H4CClCHCHO)2]PF6, and that formed from Fe(C5H4CHClMe)2 in air, respectively} showed diode characteristics under a nitrogen atmosphere.

Synthesis of Ferrocene and Cobaltocene Electrode Films by Electropolymerization and Their Spectral and Electrochemical Properties.

Abstract: Electroreduction of (I)-(IV) in MeCN solutions leads to deposition of stable electroactive polymeric films such as (V) (from (I)) on glassy-carbon and indium tin oxide coated glass electrodes.