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.

/pdf/visible-light-photocatalysis-in-nitrogen-doped-titanium-np6nklr9gh.pdf

Visible-Light Photocatalysis in Nitrogen-Doped Titanium Oxides

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

The surface science of titanium dioxide

Photo-illumination effects have been measured for the compound [Co III-LS (tmpda)(3,6-DBSQ)(3,6-DBCat)]. When the aforementioned compound was illuminated at 5 K, the magnetization value increased from w eff = 1.87 to 2.03 w B . The absorption spectra after illumination show that the absorption band at around 730 nm, which is characteristic of the [Co II-HS (tmpda)(3,6-DBSQ) 2 ] state, increased in intensity and that the charge transfer band from 3,6-DBCat to 3,6-DBSQ at 2500 nm was reduced in intensity. IR spectra show that the C-O stretching peak at 1279 cm m 1 is decreased in intensity. These results confirm that a photo-induced intra-molecular electron transfer, [Co III-LS (tmpda)(3,6-DBSQ)(3,6-DBCat)] to; [Co II-HS (tmpda)(3,6-DBSQ) 2 ], was induced. The lifetime of the metastable state at 5 K was 15 min. Furthermore, it was found that reverse valence tautomerism can be induced by exciting the Co II-HS to 3,6-DBSQ charge transfer band in metastable [Co II-HS (tmpda)(3,6-DBSQ) 2 ].

Photo-reversible valence tautomerism in a Co compound

The study of the photoanodic reaction at the ZnO electrode in an electrolyte solution containing redox agents was carried out by means of the rotating ring-disk electrode technique. The competition reactions between the photocorrosion of ZnO and the oxidation of reducing agents were discussed focusing on the potentials of the electroactive species at the semiconductor-solution interface. The ZnO photoelectrode was stabilized in the course of the oxidation of a strong reducing agent dissolved in a solution.

Competitive Redox Reactions at the ZnO Semiconductor Photoelectrode

Hydrogen‐Bonded Liquid Crystals. Novel Mesogens Incorporating Nonmesogenic Bipyridyl Compounds Through Complexation Between H‐Bond Donor and Acceptor Moieties.

Rapid chemical decolorization reaction of HxWO3 thin films and reversible operation of photochromism of WO3

Electrospun Al2O3-TiO2 composite fibers were fabricated and characterized. Morphologies of the fibers after calcination at 500, 1000 and 1150°C, respectively, were examined by SEM, which showed that the diameters of the fibers decreased with increasing calcination temperature. XRD and TGA/DTA revealed that the Al2O3-TiO2 fibers consisted of α-Al2O3 and rutile TiO2 phases after calcination above 1150°C. FE-SEM images showed that the Al2O3-TiO2 composite was consisted of both small round particles and large block-like ones, which were assigned as α-Al2O3 and rutile TiO2 crystals, respectively. The Al2O3-TiO2 fibers displayed a photocatalytic reaction to decompose acetaldehyde under UV irradiation.

Akira Fujishima

Papers

Photo-reversible valence tautomerism in a Co compound

Competitive Redox Reactions at the ZnO Semiconductor Photoelectrode

Hydrogen‐Bonded Liquid Crystals. Novel Mesogens Incorporating Nonmesogenic Bipyridyl Compounds Through Complexation Between H‐Bond Donor and Acceptor Moieties.

Rapid chemical decolorization reaction of HxWO3 thin films and reversible operation of photochromism of WO3

Electrospun fibers composed of Al2O3-TiO2 nanocrystals