Recent Developments in TiO₂ Photocatalysis: Novel Applications
to Interior Ecology Materials and Energy Saving Systems

Hiroshi IRIE, Kayano SUNADA, and Kazuhito HASHIMOTO　^＊

Research Center for Advanced Science and Technology (RCAST), The University of Tokyo (4‐6‐1 Komaba, Meguro‐ku, Tokyo 153‐8904, Japan)

Received August 25, 2004 ; Accepted September 24, 2004

Although building materials coated with photoactive TiO₂ show remarkable self‐cleaning and anti‐fogging effects outdoors by absorbing UV rays from the sun, they do not function indoors. This is because the UV light intensity indoors is too weak for a simple TiO₂ coating to exhibit either photocatalysis or photo‐induced hydrophilicity. In order to obtain interior photoactive building materials, herein we report three different types of materials based on TiO₂, which can function even under room light conditions. First is a TiO₂ film deposited with Cu that shows a remarkable antibacterial effect since the TiO₂ photocatalytic reaction assists the intrusion of antibacterial copper ions into cells. Thus, even very weak UV light is sufficient to lower cell activity. Second is a layered TiO₂／WO₃ heterogeneous film, which becomes highly hydrophilic even under fluorescent light since the photo‐generated holes produced in WO₃ by UV light are transferred to the TiO₂ side and then used for hydrophilic conversion. Third is a nitrogen doped TiO₂ film, which can be highly hydrophilic by absorbing only visible light. In addition, we demonstrate a novel application of outdoor building materials coated with TiO₂ to environmental technology using its photo‐induced high hydrophilicity. By noting that a very thin water film can form on a highly hydrophilic surface and evaporation can effectively lower the temperature by robbing the latent heat from surroundings, we proposed a novel method for cooling the surfaces of buildings and their atmospheres, i.e., a small amount of water is continuously poured onto the surface of TiO₂ coated materials. We show that this method can even reduce the temperature of a room, resulting in an energy conservation.

Removing Characteristic of Indoor Air Pollutants According to
Activated Carbon Pot and Plant Using a Tin Oxide Gas Sensor

Takashi OYABU,^a＊ Ayako SAWADA,^b Tomoaki HASHIMOTO,^c and Takayuki YOSHIOKA　^c

^aGraduate School of Regional Economic Systems, Kanazawa Seiryo University (Gosho‐machi 10, Kanazawa, Ishikawa 920‐8620, Japan)
^bSchool of Knowledge Science, Japan Advanced Institute of Science and Technology (Asahidai 1‐1, Tatsunokuchi, Ishikawa 923‐1211, Japan)
^cTokyo Metropolitan Agricultural Experiment Station (Fujimi‐machi 3‐8‐1, Tachikawa, Tokyo 190‐0013, Japan)

Received June 18, 2004 ; Accepted September 14, 2004

Activated carbon has a high porous structure and it can absorb many kinds of chemical substances in an atmosphere. In this study, the capability was examined for formaldehyde, toluene and xylene using a tin oxide gas sensor, which are named as VOCs(volatile organic compounds). An interior plant pot was made of the activated carbon and was adopted as a subject. It had a high capability to remove those chemicals. The pot, which was installed in an experimental chamber, could absorb entirely the formaldehyde of about 6.5 ppm in five hours. It also had a removing capability to larger molecular weight chemicals, for example toluene and xylene. The sensor has higher sensitivity to the gases because there are a lot of free radicals on the sensor surface and many free electrons generate in the sensor bulk. Based on these results, the three pots were installed in a real office room and examined the removing capability. In the room, the formaldehyde was emitted continuously and the saturated concentration was almost constant. The concentration was decreased until 60％ by installing the pots. They had a high removing capability to continuously emitting formaldehyde. The sensor output was sometimes calibrated by a formaldehyde measuring instrument. In the experimental room, temperature, humidity, light intensity, oxygen and carbon dioxide concentrations were also measured simultaneously. The characteristics had a correlation each other.

Electrochemical Catalytic Dechlorination of Chlorobenzene
on the Polypyrrole (Pd) Coated Electrode

Nobuhiro TAKANO, Takashi HOSHINO, and Aki KOBAYASHI

Department of Applied Chemistry, Muroran Institute of Technology (27‐1 Mizumoto‐cho, Muroran‐shi, Hokkaido 050‐8585, Japan)

Received May 27, 2004 ; Accepted August 20, 2004

The catalytic polymer film electrode which was coated with a poly ［N‐(6‐aminohexyl) pyrrole］ film on carbon‐fiber and incorporated palladium microparticles in the film was prepared. By use of the electrode the electrochemical catalytic dechlorination of chlorobenzene in 50％ alcoholic solutions led to the formation of benzene in good yields.

Ultrasonic Effects on Electroorganic Processes. Part 26.
Current Efficiency and Product Selectivity in the Anodic Cyanation
of N‐Methylpyrrole

Mahito ATOBE,^＊ Takashi AOYAGI, Toshio FUCHIGAMI, and Tsutomu NONAKA　^a

Department of Electronic Chemistry, Tokyo Institute of Technology (Mail Box G１‐3,4259 Nagatsuta, Midori‐ku, Yokohama 226‐8502, Japan)
^aTsuruoka National College of Technology (104 Aza‐sawada, Oaza‐ioka, Tsuruoka 997‐8511, Japan)

Received May 27, 2004 ; Accepted September 6, 2004

Ultrasonic effect on the anodic cyanation of N‐methylpyrrole was examined. Current efficiency and product selectivity for the monocyanated product formed by two‐electrons oxidation along with dicyanated product formed by four‐electrons oxidation, were significantly increased under ultrasonication. Moreover, it was also found that considerably high efficiency and selectivity could be obtained under ultrasonication even if the concentration of cyanide as a nucleophile was decreased. This is desirable from an environmental viewpoint.

Surface Morphology and Composition of GaN Subjected to
Photoelectrochemical Etching in KOH Aqueous Solution

Mitsubishi Electric Corporation Advanced Technology R＆D Center (Tsukaguchi Honmachi 8‐1‐1, Amagasaki, Hyogo 661‐8661, Japan)

Received May 27, 2004 ; Accepted August 26, 2004

n‐ and p‐type GaN were photoelectrochemically etched in 1M KOH under UV light illumination to investigate the relationship between photoelectrochemical etching properties, surface morphologies, and surface composition. The anodic dissolution of GaN was enhanced by UV light illumination. The surface morphology of GaN subjected to photoelectrochemical etching strongly depended on the type of doping. After photoelectrochemical etching, crystallographic orientated inhomogeneous structure formed on the n‐GaN, and several pits formed on the p‐GaN surface. Cathodic current was only observed in the p‐GaN, and the current was caused by the reduction of oxygen or protons. Apparent changes of surface composition were not observed between GaN as received or subjected to photoelectrochemical etching. The XPS spectra suggested that the surface concentration of oxide formed on n‐GaN subjected to photoelectrochemical etching was identical to the as received n‐GaN.

Electrochemical Prevention of Biofouling Using Pt／IrO₂‐Coated
Titanium Electrode

^aCentral Research Laboratory, Pentel Co., Ltd. (4‐1‐8 Yoshi‐cho, Soka, Saitama 340‐0017, Japan)
^bR＆D Department, Ishifuku Metal Industry Company Ltd. (2‐12‐30 Aoyagi, Soka, Saitama 340‐0002, Japan)
^cDepartment of Biotechnology, Tokyo University of Agriculture and Technology (2‐24‐16 Nakacho, Koganei, Tokyo 184‐8588, Japan)

Received May 19, 2004 ; Accepted September 6, 2004

Pt／IrO₂‐coated titanium was developed as the electrode for prevention of biofouling. When a potential of 0.9V vs. Ag／AgCl was applied to the Pt／IrO₂‐coated titanium electrode in seawater, 3％ of marine bacteria attached to the electrode survived after 60min. Almost no change in pH and chlorine concentration was observed after applying 0.9V vs. Ag／AgCl in the bulk seawater. When alternating potentials of 0.9V vs. Ag／AgCl and cycling potentials of −0.3〜−0.9V vs. Ag／AgCl were applied, prevention of biofouling was successfully achieved in the field experiment. Also, cleaning of electrode surface was achieved electrochemically by applying the potential of 1.0V vs.Ag／AgCl.

Destruction of 1, 2, 3‐trichlorobenzene in Sediment Extract
by Na Ion Supply System

^aInstitute of Applied Biochemistry, University of Tsukuba (1‐1‐1 Tennodai, Tsukuba, Ibaraki 305‐8572, Japan)
^bIshifuku Metal Industry Co., LTD (Soka First Plant 2‐12‐30 Aoyagi, Soka, Saitama 340‐0002, Japan)

Received May 28, 2004 ; Accepted September 1, 2004

Destruction of Persistent Organic Pollutants (POPs) in the environment is urgent due to the health hazards they impose. In this study, detoxification of dechlorination of 1, 2, 3‐trichlorobenzene as a model POPs was investigated using an environment‐friendly electrochemical system. The system operates more rapidly under relatively lesser amount of solvent compared with other known systems. The Na ion electrolytes act as mediator with catalytic PdO sintered cathode electrode. The dechlorination yield was 87.4％.

Polarized Potential Window Available at the Interface Between an
Aqueous Electrolyte Solution and Tetraalkylammonium Imide Salts

Department of Energy and Hydrocarbon Chemistry, Graduate School of Engineering, Kyoto University (Nishikyoku, Kyoto 615‐8510, Japan)

Received June 11, 2004 ; Accepted August 28, 2004

The polarized potential window (ppw) of 450 mV is available at the interface between water (W) and the room‐temperature molten salt (RTMS) that consists of tetraoctylammonium cations and trifluoromethylsulfonylnonafluorobutylsulfonylimide anions. The ppw at the interface between W and RTMS made of several combinations of hydrophobic cations and anions is correlated with the standard ion‐transfer potentials of the ions at the 1,2‐dichloroethane｜W interface. This correlation is useful not only to predict the width of the ppw but also to approximately estimate the point of zero charge at the RTMS｜W interface.

Mineralization of Aqueous Benzenesulfonates
by Contact Glow Discharge Electrolysis

Department of Material Science and Engineering, Graduate School of Engineering, Saitama Institute of Technology (1690 Fusaiji, Okabe, Saitama 369‐0293, Japan)

Received June 28, 2004 ; Accepted September 1, 2004

Contact glow discharge electrolysis(CGDE) of benzenesulfonates in a neutral phosphate buffer solution was investigated. Benzenesulfonic acid was smoothly degraded and eventually mineralized to inorganic carbon and sulfate ion. As the intermediate products, some phenolic compounds were detected as well as carboxylic acids such as oxalate and formate. Also in CGDE of p‐toluenesulfonic acid, quite similar results were obtained. Based on the products and kinetic consideration, it was assumed that hydroxyl radicals would play a crucial role in the oxidative degradation of aqueous benzenesulfonates.

Photocatalytic Degradation of Organic Pollutants
in Room‐Temperature Ionic Liquids

Department of Electronic Chemistry, Tokyo Institute of Technology (4259 Nagatsuta, Midori‐ku, Yokohama 226‐8502, Japan)

Received June 29, 2004 ; Accepted September 9, 2004

Photocatalytic degradation of organic pollutants such as naphthol blue black (NBB), Amarance, and 2‐chlorophenol (2CP) was carried out in ionic liquids. The photocatalytic degradation rates of the former two azo dyes were greatly enhanced in ionic liquids compared with those in water. In sharp contrast, the photocatalytic degradation of 2CP was not efficient in an ionic liquid, however the degradation was enhanced under simultaneous ultrasonication.

Electrochemical Partial Fluorination of Organic Compounds (76).
Selective Anodic Fluorination of N‐Protected Pyrroles
Towards Environmentally Friendly Process

Department of Electronic Chemistry, Tokyo Institute of Technology (4259 Nagatsuta, Midori‐ku, Yokohama 226‐8502, Japan)

Received June 29, 2004 ; Accepted September 6, 2004

Anodic fluorination of 1‐tosylpyrrole and 2‐cyano‐1‐tosylpyrrole was successfully carried out to provide the fluorinated products in high yields. This is the first report of successful anodic fluorination of N‐protected pyrrole derivatives.

N‐Oxyl‐Mediated Electrooxidation in Ionic Liquid.
A Prominent Approach to Totally Closed System

Department of Applied Chemistry, Faculty of Engineering, Okayama University (Tsushima‐naka 3‐1‐1, Okayama 700‐8530, Japan)

Received June 29, 2004 ; Accepted September 6, 2004

N‐Oxyl‐mediated electrooxidation of sec‐alcohols in ionic liquids was performed successfully to give the corresponding ketones. By use of ionized N‐oxyl, ［TEMPOmim］［Tf₂N］, both the ionic liquids and the N‐oxyl compound could be recovered and reused for the electrooxidation of alcohols.

Electrocatalytic Debromination of Organic Bromides
Using a Cobalt(II)salen Complex in Ionic Liquids

Yi SHEN, Toshiki TAJIMA, Mahito ATOBE, and Toshio FUCHIGAMI　^＊

Department of Electronic Chemistry, Tokyo Institute of Technology (4259 Nagatsuta, Midori‐ku, Yokohama 226‐8502, Japan)

Received June 29, 2004 ; Accepted September 11, 2004

The catalytic effect of a Co(II)salen mediator on the reduction of cyclic vic‐dibromide was investigated in ionic liquids by cyclic voltammetry. Macro‐scale controlled potential electrolysis gave the corresponding debrominated product in moderate to good yields. The workup after electrolysis in an ionic liquid proved to be much simpler than that in organic solvents. The possibility of reuse of the ionic liquid was demonstrated to some extent.

Electrochemical Dechlorination of Chlorobenzene in Acetonitrile with
Various Water Concentrations

Nagahiro HOSHI,^＊ Akihiro HAGA, and Yoshio HORI

Department of Applied Chemistry and Biotechnology, Faculty of Engineering, Chiba University (1‐33, Yayoi‐cho, Inage‐ku, Chiba 263‐8522, Japan)

Received June 30, 2004 ; Accepted September 13, 2004

Electrochemical reduction of chlorobenzene has been studied on a silver polycrystalline electrode in acetonitrile solution containing various concentrations of water. The main product is benzene. The partial current density of benzene j_C6H6 is enhanced with the increase of the concentration of chlorobenzene linearly. The value of j_C6H6 is independent of the concentration of water. This result differs from the electrolysis of chloroform in which the partial current density of the product (methane) is enlarged with the increase of the water concentration remarkably. The electrolysis in acetonitrile containing D₂O shows that the proton source of benzene is acetonitrile as well as water.

Utilization of Bis(trimethylsilyl)fluorenes as Protected Fluorenes
and Fluorenones. Effective Electrooxidative Conversion
into Fluorenone Dimethyl Acetals

Makoto KIMURA,^＊ Takahiro KAWAI, and Yasuhiko SAWAKI

Department of Applied Chemistry, Graduate School of Engineering, Nagoya University (Furo‐cho, Chikusa, Nagoya, 464‐8603, Japan)

Received July 6, 2004 ; Accepted September 7, 2004

9,9‐Bis(trimethylsilyl)fluorene (1) was prepared in one‐pot procedure using LDA as base. The bis‐silane 1 can act as a masked fluorene because of facile conversion to fluorene with methanol containing sodium methoxide. More specifically, 1 is smoothly transformed into fluorenone dimethyl acetal by electrooxidation in methanol; various chemical oxidants fail to react with an exception of CAN which led to fluorenone. The electrolysis of 1 involves an intermediary formation of the mono‐methoxylated monosilane, which undergoes more facile conversion than 1.

Electrochemical Oxidation of Glucose to Glucarate Using TEMPO
as a Mediator in an Alkaline Solution

Tesshu KOGA and Isao TANIGUCHI　^＊

Department of Applied Chemistry and Biochemistry, Kumamoto University (2‐39‐1, Kurokami, Kumamoto 860‐8555, Japan)

Received July 6, 2004 ; Accepted September 29, 2004

The TEMPO (2,2,6,6‐tetramethyl‐１‐piperidinyloxyl)‐mediated electrochemical oxidation of glucose at ＋0.6V gave glucarate as a main product when the concentration ratios of glucose to TEMPO (2 mM) were roughly 1 to 10 with a current efficiency of ＞ ca. 50％ using a glassy carbon electrode in a 1 M NaOH solution, in which TEMPO showed a reversible one‐electron redox reaction at ＋0.46V (vs. Ag／AgCl) to the nitrosonium cation.

Mixed Protonic‐Electronic Conduction Properties
of SrZr_0.9−xY_0.1Ru_xO_3−α

Hiroshige MATSUMOTO,^＊a,d Tetsuo SHIMURA,^b Tohru HIGUCHI,^c
Takanori OTAKE,^a Yusuke SASAKI,^a Keiji YASHIRO,^a Atsushi KAIMAI,^a
Tatsuya KAWADA,^a and Junichiro MIZUSAKI　^a

^aInstitute of Multidisciplinary Research for Advanced Materials, Tohoku University (2‐1‐1 Katahira, Aoba‐ku, Sendai 980‐8577, Japan)
^bEcotopia Science Institute, Nagoya University (Furo‐cho, Chikusa‐ku, Nagoya 464‐8603, Japan)
^cDepartment of Applied Physics, Tokyo University of Science (1‐3 Kagurazaka, Shinjyuku‐ku, Tokyo 162‐8601, Japan)
^dPresent address: Department of Applied Chemistry, Faculty of Enginearing, Kyushu University (6‐10‐1 Hakozaki, Higashi‐ku, Fukuoka 812‐8581, Japan)

Received July 6, 2004 ; Accepted August 24, 2004

Protonic‐electronic mixed‐conducting properties have been investigated for SrZr_0.9−xY_0.1Ru_xO_3−α (x＝0.05−0.125) at elevated temperatures. Hydrogen permeation was actually observed with respect to the ambipolar diffusion, ensuring the ionic‐electronic mixed conduction in the materials. The mixed‐conducting mechanism is revealed by electrochemical and spectroscopic measurements.

DFT Study for CO and H₂ Adsorption and Related Reactions
on Pt alloy Electrode

Yoshiki SHIMODAIRA,^a Toshiko MIURA,^b Tetsuyuki OKUMACHI,^b Tokio YAMABE,^c
Akihiko KUDO,^a and Hisayoshi KOBAYASHI　^b＊

^aDepartment of Applied Chemistry, Faculty of Science, Science University of Tokyo (1‐3 Kagurazaka, Shinjuku‐ku, Tokyo 162‐8601, Japan)
^bDepartment of Chemistry and Bioscience, Kurashiki University of Science and the Arts (2640 Nishinoura, Tsurajima, Kurashiki 712‐8505, Japan)
^cNagasaki Institutes of Applied Science (536, Amiba‐cho, Nagasaki, 851‐0193, Japan)

Received June 30, 2004 ; Accepted September 20, 2004

The density functional theory (DFT) calculation has been applied to investigate CO and H₂ adsorption onto Pt‐Ru, Pt‐Rh, Pt‐Pd, Pt‐Ag alloys as well as Pt metal modeled by Pt_xM_10−x (M＝Ru, Rh, Pd, Ag, and x＝3, 5, 7) clusters. The most durable catalysts for CO poisoning were searched using the criteria that adsorption of CO should be weakened compared to pure Pt but adsorption of H₂ should not be weakened, or activation energy for the H‐H bond fission is not increased. Pt₅Ru₅ and Pt₇Ru₃ were the best catalyst in conformity with many experimental works. Slab calculation showed that Pt is more localized in the surface layer than the bulk content in Pt‐Ru alloy. Energy profiles calculated for the two reactions, CO ＋ OH → COOH and H₂O → OH ＋ H were compared between Pt and Pt‐Ru alloy. No significant advantage for Pt‐Ru alloy was found for the former reaction, but OH formation was more facile for the Ru site of Pt‐Ru alloy.

Thermoelectric Properties, Defect Structure, and Electronic Structure
of Ln_0.9Sr_0.1FeO_3−δ, (Ln＝La and Nd)

Kiyoshi KOBAYASHI,^a＊ Shu YAMAGUCHI,^b Toru HIGUCHI,^c Shik SHIN,^d
Takeyo TSUKAMOTO,^c and Tatsuo TSUNODA　^e

^aLaboratory for Membrane Chemistry, AIST Tohoku, National Institute of Advanced Industrial Science and Technology (4‐2‐1, Nigatake, Miyagino‐ku, Sendai 983‐8551, Japan)
^bDepartment of Material Science and Engineering, School of Engineering, The University of Tokyo (7‐3‐1, Hongo, Bunkyo‐ku, Tokyo 113‐8656, Japan)
^cFacility of Science, Science University of Tokyo (1‐3, Kagurasaka, Shinjuku‐ku, Tokyo 162‐0825, Japan)
^dInstitute of Solid State Physics, The University of Tokyo (Tanashi, Tokyo 188‐8501, Japan)
^eAdvanced Manufacturing Research Institute, National Institute of Advanced Industrial Science and Technology (Tsukuba Central 5, 1‐1‐1 Higashi, Tsukuba 305‐8565, Japan)

Received June 29, 2004 ; Accepted August 19, 2004

The electrical conductivity, thermoelectric power, and thermal conductivity of Ln_0.9Sr_0.1FeO_3−δ (Ln＝La and Nd) were measured as functions of temperature and oxygen partial pressure, and the electrical transport parameters were calculated using the defect model. It was found that the values of hole mobility, the equilibrium constant of the annihilation reaction for the oxide ion vacancy, thermal conductivity of La_0.9Sr_0.1FeO_3−δ are larger than the values of Nd_0.9Sr_0.1FeO_3−δ, while the thermoelectric power of La_0.9Sr_0.1FeO_3−δ is smaller than those of Nd_0.9Sr_0.1FeO_3−δ at the same hole concentration and temperature. Based on the X‐ray absorption spectroscopy measurements, it is suggested that the thermoelectric properties of La_0.9Sr_0.1FeO_3−δ and Nd_0.9Sr_0.1FeO_3−δ are affected by the covalency of iron ions.

Synthesis of Tungsten, Molybdenum and Vanadium Bronzes
by Mechanochemical Method Milling with Liquid Hydrocarbons

Shigeomi TAKAI, Nobutaka HOSHIMI, and Takao ESAKA　^＊

Department of Materials Science, Faculty of Engineering, Tottori University (Minami 4‐101, Koyamacho, Tottori 680‐0945, Japan)

Received July 6, 2004 ; Accepted September 29, 2004

The oxide bronzes have been synthesized by the mechanochemical method. It was found that the deep‐blue tungsten bronze was obtained by more than 12 hours milling with adding the non‐polar liquid hydrocarbons. X‐ray diffraction and TG‐DTA measurements revealed that hydrogen content in the obtained bronzes can be controlled by milling time. Molybdenum and vanadium bronzes were also found to be formed by milling MoO₃ and V₂O₅ powders milled with xylene. A self‐supported membrane was prepared by casting the milled molybdenum bronze and ion exchange resin with acethilcellrose, which was electrolyzed to observe the elecrochromic behavior.

Application of the photoeffect in TiO₂
for cathodic protection of copper

Raghavan SUBASRI and Tadashi SHINOHARA　^＊

Corrosion Group, Materials Information Technology Station National Institute for Materials Science (1‐2‐1, Sengen, Tsukuba, Ibaraki 305‐0047, Japan)

Received July 13, 2004 ; Accepted September 13, 2004

Photoelectrochemical characterization of copper specimens coated with a bilayer photoanode bearing the configuration Cu ｜Sb‐SnO₂｜SnO₂＋TiO₂ was carried out for verifying the suitability of such coatings for a cathodic protection of copper in presence of ultraviolet illumination. An optimization of the heat‐treatment temperature of the coatings was accomplished which showed that a 200℃ heat treatment was sufficient to obtain a desirable photoeffect. The results of the present investigation also showed that such bilayer photoanodes are functional for cathodic protection applications in the case of copper only under conditions of low oxygen potentials. A continued cathodic protection was possible even after cessation of ultraviolet illumination due to a charge storage of the photogenerated electrons transferred from TiO₂ to SnO₂, which could be slowly released to the metal substrate continuing to offer a cathodic protection under no illumination conditions.