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.
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.
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 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.
n- and p-type GaN were photoelectrochemically etched in 1 M 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.
Pt/IrO2-coated titanium was developed as the electrode for prevention of biofouling. When a potential of 0.9 V vs. Ag/AgCl was applied to the Pt/IrO2-coated titanium electrode in seawater, 3% of marine bacteria attached to the electrode survived after 60 min. Almost no change in pH and chlorine concentration was observed after applying 0.9 V vs. Ag/AgCl in the bulk seawater. When alternating potentials of 0.9 V vs. Ag/AgCl and cycling potentials of −0.3 ≫ −0.9 V 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 1.0 V vs. Ag/AgCl.
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%.
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 trifluoromethylsulfonylnonafluoro-butylsulfonylimide 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.
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 such as naphthol blue black (NBB), Amarance, and 2-chlorophenol (2 CP) 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.
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 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.
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 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 jC6H6 is enhanced with the increase of the concentration of chlorobenzene linearly. The value of jC6H6 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.
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.
The TEMPO (2,2,6,6-tetramethyl-l-piperidinyloxyl)-mediated electrochemical oxidation of glucose at + 0.6 V 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 + 0.46 V (vs. Ag/AgCl) to the nitrosonium cation.
Protonic-electronic mixed-conducting properties have been investigated for SrZr0.9−xY0.1RuxO3−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.
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 PtxM10−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.
The electrical conductivity, thermoelectric power, and thermal conductivity of Ln0.9Sr0.1FeO3−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 La0.9Sr0.1FeO3−δ are larger than the values of Nd0.9Sr0.1FeO3−δ, while the thermoelectric power of La0.9Sr0.1FeO3−δ is smaller than those of Nd0.9Sr0.1FeO3−δ at the same hole concentration and temperature. Based on the X-ray absorption spectroscopy measurements, it is suggested that the thermoelectric properties of La0.9Sr0.1FeO3−δ and Nd0.9Sr0.1FeO3−δ are affected by the covalency of iron ions.
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.
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°C 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.