Plastic Dye-sensitized Photovoltaic Cells and Modules Based on Low-
temperature Preparation of Mesoscopic Titania Electrodes

Tsutomu MIYASAKA,^＊ Yujiro KIJITORI, and Masashi IKEGAMI

Graduate School of Engineering, Toin University of Yokohama (1614 Kurogane-cho, Aoba, Yokohama, Kanagawa 225-8502, Japan)

Received August 24, 2006 ; Accepted November 9, 2006

Recent trend in industries toward the development of thin opto-electronic devices requires flexibility and safety for versatile applications including ubiquitous electric generators. Dye-sensitized mesoporous semiconductor electrodes can be a powerful candidate for fabrication of low-cost flexible photovoltaic devices. This review introduces low-temperature coating methods for fixing mesoporous TiO₂ films on conductive plastic electrodes. Characteristics of plastic dye-sensitized solar cells assembled by this technology are also summarized, including outdoor performance of large-area full-plastic modules in comparison with commercial silicon-based solar batteries.

High-performance Surface Plasmon Resonance Immunosensors for
TNT Detection

Norio MIURA,^a＊ Dhesingh Ravi SHANKARAN,^{a, b} Toshikazu KAWAGUCHI,^a
Kiyoshi MATSUMOTO,^c and Kiyoshi TOKO^d

^aArt, Science and Technology Center for Cooperative Research, Kyushu University (Kasuga-shi, Fukuoka 816-8580, Japan)
^bJapan Society for the Promotion of Science (Tokyo102-8471, Japan)
^cGraduate School of Agriculture, Kyushu University (Fukuoka 812-8581, Japan)
^dGraduate School of Information Science and Electrical Engineering, Kyushu University (Fukuoka 819-0395, Japan)

Received August 26, 2006 ; Accepted October 25, 2006

Detection of 2,4,6-trinitrotoluene (TNT) is an important environmental, security and health concern for the global community. TNT is a prime constituent of most of the landmines and bombs and is highly toxic and mutagenic. Various military and terrorist activities (e.g., manufacturing, waste discharge, testing and training) have resulted in extensive contamination of soil and ground water by TNT and its derivatives. Consequently, the development and application of new sensing techniques for detection and quantification of TNT has grown steadily over the years. Despite wide variety of analytical techniques, surface plasmon resonance (SPR) based immunosensors received great attention as a promising mean for TNT detection due to their advantages including high sensitivity, selectivity, good versatility and high throughput. This review explores the recent trend and advancements in immunochemical techniques for environmental monitoring and field detection of TNT. The advantages of the surface plasmon resonance as an optical signal transduction and indirect competitive immunoassay as the sensing principle are discussed with special emphasis on our investigations on TNT detection. A brief description on explosives, landmines and the current detection techniques (bulk and trace detection) is also provided.

Ionic Liquids for Electrochemical Devices

Rika HAGIWARA and Je Seung LEE

Graduate School of Energy Science, Kyoto University (Sakyo-ku, Kyoto 606-8501, Japan)

Received September 11, 2006 ; Accepted October 25, 2006

Dedicated to Prof. Dr. Neil Bartlett on the occasion of his 75th birthday

A short review of ionic liquids (ILs) and their applications as electrolytes for electrochemical devices, such as electric double layer capacitors, fuel cells, lithium batteries, and solar cells, are presented here. The properties of ILs, such as non-volatility, non-flammability, wide liquid temperature ranges, and wide electrochemical windows, have the potential to be improved, including improvements in durability and safety, extending the operational temperature ranges and enabling improvements in power and energy densities of the devices.

Accelerated Electron-Transfer Reaction of the O₂/O₂⁻ Redox Couple on
Multi-Walled Carbon Nanotubes ― Modified Edge-Plane Pyrolytic
Graphite Electrode in Room-Temperature Ionic Liquids

Keqiang DING, Takeyoshi OKAJIMA, and Takeo OHSAKA^＊

Department of Electronic Chemistry, Interdisciplinary Graduate School of Science and Engineering, Tokyo Institute of Technology (Mail Box G1-5, 4259 Nagatsuta, Midori-ku, Yokohama 226-8502, Japan)

Received September 07, 2006 ; Accepted October 19, 2006

An electrocatalysis of the multi-walled carbon nanotubes (MWCNTs)/Nafion-modified edge-plane pyrolytic graphite (EPPG) electrode for the one-electron reduction-oxidation reaction of the O₂/O₂^- (superoxide ion) redox couple in three 1-n -alkyl-3-methylimidazolium tetrafluoroborate room temperature ionic liquids (RTILs), 1-ethyl-3-methylimidazolium tetrafluoroborate (EMIBF₄), 1-n -propyl-3-methylimidazolium tetrafluoroborate (PMIBF₄) and 1-n -butyl-3-methylimidazolium tetrafluoroborate (BMIBF₄) has been found. We have observed that in all the RTILs both the cathodic and anodic peak currents and the peak potential separations (ΔE_p) between the anodic and cathodic peak potentials at the MWCNTs/Nafion-modified electrode are increased and decreased, respectively, compared with those at the bare electrode. The values of the standard rate constant (k ⁰) were estimated from the ΔE_p values, i.e., the k ⁰ values at the MWCNTs/Nafion-modified electrode are (8.3±0.1)×10^-3, (10.4±0.1)×10^-3 and (4.2±0.1)×10^-3 cm s^-1 in EMIBF₄, PMIBF₄ and BMIBF₄, respectively, while the corresponding values at the bare electrode are (4.3±0.1)×10^-3, (2.9±0.1)×10^-3 and (2.3±0.1)×10^-3 cm s^-1, respectively. The observed enhancement of the O₂/O₂^- redox reaction is discussed briefly based on the catalytic effects and physicochemical properties of carbon nanotubes.

Electrocatalytic Activity of Pt and Ru Photodeposited Polyaniline
Electrodes for Methanol Oxidation

Satoshi ARIMOTO, Hiroyuki NAKANO, Takeshi FUJITA, Yasuhiro TACHIBANA,
and Susumu KUWABATA^＊

Department of Applied Chemistry, Graduate School of Engineering, Osaka University (Suita, Osaka 565-0871, Japan)

Received July 18, 2006 ; Accepted October 30, 2006

Photochemical deposition of Pt, Ru or both on polyaniline and their electrocatalytic activity for methanol oxidation were investigated. The deposition quantity was easily controlled since it was proportional to light irradiation time. The highest activity, i.e., the largest anodic current density and the most negative onset potential, of the metal deposited polyaniline electrode were obtained by adjusting Pt/Ru deposition ratio appropriately. From a TEM image, the photodeposited metal particle size was determined to be 1〜2 nm. The bifunctional roles of the polyaniline, as a photocatalyst and an electron conductor, are also discussed.

Molecular Orbital Study on the Oxidation Mechanism of Hydrazine and
Hydroxylamine as Reducing Agents for Electroless Deposition Process

Takuya SHIMADA,^a Amiko TAMAKI,^a Hiromi NAKAI,^b and Takayuki HOMMA^a＊

^aDepartment of Applied Chemistry, School of Science and Engineering, Waseda University (Okubo, Shinjuku-ku, Tokyo 169-8555, Japan)
^bDepartment of Chemistry, School of Science and Engineering, Waseda University (Okubo, Shinjuku-ku, Tokyo 169-8555, Japan)

Received September 30, 2006 ; Accepted November 6, 2006

The oxidation mechanism of hydrazine and hydroxylamine were investigated using molecular orbital (MO) calculation. Two pathways for their reactions were verified. One is initiated by hydrogen elimination from the reducing agent, followed by coordination of hydroxyl group to center nitrogen atom accompanied with electron emission. Another is initiated by coordination of hydroxyl group to hydrogen atom to form H₂O, which is eliminated later, followed by electron emission. The calculated results indicated that the oxidation reactions of hydrazine preferentially proceeded via the second pathway. It was also indicated that only the first electron emission steps of the hydrazine oxidation took place on Cu surface, while the following reactions proceeded at near the solid/liquid interface. The oxidation of hydroxylamine also proceeded via the elimination reaction of H₂O. After the oxidation, calculated heats of reactions suggested that OH radical, generated from N₂O as a product, decomposed hydroxylamine.

Green Inhibitors for Petroleum Product Pipelines

N. MUTHUKUMAR, S. MARUTHAMUTHU, and N. PALANISWAMY^＊

Corrosion Protection Division, Central Electrochemical Research Institute (Karaikudi 630 006, India)

Received August 3, 2006 ; Accepted November 10, 2006

Impact of corrosion inhibitors on environment has received increased attention in recent years. The new generation of environmental regulations requires the replacement of toxic chemicals with so-called "Green chemicals". In the present study neem oil, castor oil and punga oil were used for corrosion inhibition evaluation in petroleum product (diesel) along with 2% water containing 120ppm chloride. Weight loss and polarization studies were employed to find out the corrosion inhibition efficiency (IE). Weight loss study revealed that castor oil gave higher efficiency (89%) when compared to other neem oil and punga oil. The mechanism of corrosion inhibition was investigated by using surface techniques viz., Fourier transform infrared spectroscopy (FTIR) and scanning electron microscope (SEM).

Electropolymerization of 9,9-dialkyl-substituted Fluorenes with Long Alkyl Chains and Redox Responses of the Resulting Electroactive Films for Electrochemical Capacitor Materials

Shunzo SUEMATSU,^a＊ Koichi MITSUDO,^b Fumiaki KATAGIRI,^b and Hideo TANAKA^b＊

^a Research Center, Nippon Chemi-con Corporation (363, Takahagi-shi, Ibaraki 318-8505, Japan)
^b Department of Applied Chemistry, Faculty of Engineering, Okayama University (Okayama 700-8530, Japan)

Received September 25, 2006 ; Accepted October 16, 2006

Electropolymerization of 9,9-dialkylfluorenes (R_nfluo, n: number of carbons in the chain) with long normal alkyl chains (n ＝4, 5, 6, 8, and 10 compared with n ＝1) were investigated during sequential potential cycling. Among the R_nfluos, significant film growths were observed for the R_nfluo with n ＝1, 8, and 10. The R₈fluo and R₁₀fluo-based films were also found to consist of the monomer unit with higher molecular weight than the R₁fluo-based film. A doping/undoping response of the new electroactive poly(R₁₀fluo) film was compared with that of poly(R₈fluo) from a fundamental viewpoint as an electrochemical capacitor material.