ALTHOUGH the possibility of water photolysis has been investigated by many workers, a useful method has only now been developed. Because water is transparent to visible light it cannot be decomposed directly, but only by radiation with wavelengths shorter than 190 nm (ref. 1).

Electrochemical Photolysis of Water at a Semiconductor Electrode

Although gold is the subject of one of the most ancient themes of investigation in science, its renaissance now leads to an exponentially increasing number of publications, especially in the context of emerging nanoscience and nanotechnology with nanoparticles and self-assembled monolayers (SAMs). We will limit the present review to gold nanoparticles (AuNPs), also called gold colloids. AuNPs are the most stable metal nanoparticles, and they present fascinating aspects such as their assembly of multiple types involving materials science, the behavior of the individual particles, size-related electronic, magnetic and optical properties (quantum size effect), and their applications to catalysis and biology. Their promises are in these fields as well as in the bottom-up approach of nanotechnology, and they will be key materials and building block in the 21st century. Whereas the extraction of gold started in the 5th millennium B.C. near Varna (Bulgaria) and reached 10 tons per year in Egypt around 1200-1300 B.C. when the marvelous statue of Touthankamon was constructed, it is probable that “soluble” gold appeared around the 5th or 4th century B.C. in Egypt and China. In antiquity, materials were used in an ecological sense for both aesthetic and curative purposes. Colloidal gold was used to make ruby glass 293 Chem. Rev. 2004, 104, 293−346

Gold nanoparticles: assembly, supramolecular chemistry, quantum-size-related properties, and applications toward biology, catalysis, and nanotechnology.

To use solar irradiation or interior lighting efficiently, we sought a photocatalyst with high reactivity under visible light. Films and powders of TiO 2- x N x have revealed an improvement over titanium dioxide (TiO 2 ) under visible light (wavelength 2 has proven to be indispensable for band-gap narrowing and photocatalytic activity, as assessed by first-principles calculations and x-ray photoemission spectroscopy.

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Visible-Light Photocatalysis in Nitrogen-Doped Titanium Oxides

Titanium Dioxide Nanomaterials: Synthesis, Properties, Modifications, and Applications

The surface science of titanium dioxide

A simple, rugged home-built scanning tunneling microscope for operation in both air and liquid that uses a Z-stage micrometer to provide coarse mechanical positioning is described. The construction of this STM was accomplished at low cost without precision machining. The tunneling current is typically acquired within 10–15 minutes. The atomic resolving power of our STM has been demonstrated by a cleaved HOPG at a 15-Hz scanning rate in air. There was no use of plate-stack-type isolators, due to the high rigidness of the tunneling unit. The STM image of a HOPG in ultrapure water was also observed with a glass-coated tip. Images of a pc-Ag electrode in 0.1 mol dm−3 KCl demonstrate stable operation in a liquid solution. The lateral drift was shown to be less than 0.13 nm min−1 for operation in liquid, estimated by subsequent imaging of the same area. This STM is easy to handle and has a suitable design for in situ electrode surface characterization.

A simple and rugged home-built scanning tunneling microscope for operation in both air and liquid

Isolation and dispersion of reduced metal particles using the surface dipole moment of F-terminated diamond electrodes

Abstract Photocatalytic degradation of formic acid (HCOOH) in solution was monitored using titanium dioxide (TiO2) films supported on Pyrex and soda-lime glasses (SLG) calcined with two different calcination methods: programmed and short time (10 min) with temperature 100 and 700 °C for both methods. As the calcination temperature and duration increased, the photocatalytic activities using TiO2 films supported on SLG decreased, whereas the photocatalytic activities of TiO2 films supported on Pyrex were not much affected by calcination temperature and duration. TiO2 films supported on both Pyrex and SLG showed reduced photocatalytic activities after -50 days.

Activity, and Hardness of Supported TiO2 Films on Pyrex and Soda-Lime Glass in Photocatalytic Degradation of Formic Acid for 50 Days

Mechanism of Anodic Dissolution Reaction of ZnO Single Crystal Electrode under Irradiation

The formation of colored formazans from the reduction of colorless tetrazolium salts was found to occur on the surfaces of photoexcited TiO2 and ZnO powders in ethanol solutions. The yields of the conversions of 2,3,5-triphenyltetrazolium chloride to 1,3,5-triphenylformazan and of 2,5-diphenyl-3-(l-naphthyl)tetrazolium chloride to 1,3-diphenyl-5-(l-naphthyl)formazan were 41.6% and 40.0%, respectively, after a 25-min UV irradiation in the TiO2 suspension, whereas they were 55.8% and 35.2%, respectively, after a 60-min UV irradiation in the ZnO suspension. These reactions proceeded via photoelectrochemical reduction by the electrons from the conduction bands of the semiconductors, but were quenched in the presence of oxygen or Ag+ ions.

Akira Fujishima

Papers

A simple and rugged home-built scanning tunneling microscope for operation in both air and liquid

Isolation and dispersion of reduced metal particles using the surface dipole moment of F-terminated diamond electrodes

Activity, and Hardness of Supported TiO2 Films on Pyrex and Soda-Lime Glass in Photocatalytic Degradation of Formic Acid for 50 Days

Mechanism of Anodic Dissolution Reaction of ZnO Single Crystal Electrode under Irradiation

Photoelectrochemical Reduction of Tetrazolium Salts to Formazans on Surfaces of Semiconductor Powders in Alcohol Solutions