Soft Chemistry Routes to New Nanosize Materials

The old classical method for preparing inorganic materials is by the ceramic route or solid state reaction. It consists of mixing the starting materials at an elevated temperature. This method has been used for preparing numerous new materials until today. Three decades ago, the materials science community was aware of soft chemistry synthesis or chimie douce, especially with the emergence of nanotechnology field. Instead of the classical method, which involves high temperature, soft chemistry techniques use lower temperatures. In general, starting materials are dissolved in a liquid phase and different parameters such as pH, temperature and reaction time are adjusted in order to obtain the desired product. By using a lower temperature of preparation, the product obtained shows nanosize particles, with sizes lower than 100 nanometers. In contrast, the ceramic route (or solid state reaction) using higher temperatures leads to bigger particles size that are out of the nanosize range. Also, some interesting phases that are not stable at elevated temperatures (named metastable phases) and are not accessible by the classical method, are now prepared by the soft chemistry technique. Usually these metastable phases have interesting structural features and important physical properties. Adding to that, the product is obtained with a higher level of purity

A Raman spectroscopic study of the different vanadate groups in solid-state compounds - model case: mineral phases vesignieite [BaCu3(VO4)2(OH)2] and volborthite [Cu3V2O7(OH)2.2H2O]

Raman spectroscopy has been used to study vanadates in the solid state. The molecular structure of the vanadate minerals vésigniéite [BaCu3(VO4)2(OH)2] and volborthite [Cu3V2O7(OH)2·2H2O] have been studied by Raman spectroscopy and infrared spectroscopy. The spectra are related to the structure of the two minerals. The Raman spectrum of vésigniéite is characterized by two intense bands at 821 and 856 cm−1 assigned to ν1 (VO4)3− symmetric stretching modes. A series of infrared bands at 755, 787 and 899 cm−1 are assigned to the ν3 (VO4)3− antisymmetric stretching vibrational mode. Raman bands at 307 and 332 cm−1 and at 466 and 511 cm−1 are assigned to the ν2 and ν4 (VO4)3− bending modes. The Raman spectrum of volborthite is characterized by the strong band at 888 cm−1, assigned to the ν1 (VO3) symmetric stretching vibrations. Raman bands at 858 and 749 cm−1 are assigned to the ν3 (VO3) antisymmetric stretching vibrations; those at 814 cm−1 to the ν3 (VOV) antisymmetric vibrations; that at 508 cm−1 to the ν1 (VOV) symmetric stretching vibration and those at 442 and 476 cm−1 and 347 and 308 cm−1 to the ν4 (VO3) and ν2 (VO3) bending vibrations, respectively. The spectra of vésigniéite and volborthite are similar, especially in the region of skeletal vibrations, even though their crystal structures differ

Research and Reviews: Journal of Chemistry UV Photocatalytic Degradation of Toluene and Tetradecane Using Anatase TiO2 Crystals

ABSTRACT Crystalline titanium oxide was obtained by simple and low cost method. X-ray diffraction (XRD) measurements confirmed that the prepared TiO2 catalyst has a single anatase structure with no indication of the presence of a secondary phase. Transmission electron microscopy (TEM) micrograph demonstrates that the anatse TiO2 has spherical homogenous crystals with average diameter of 1.10 nm. Toluene and tetradecane adsorbed on the surface of titanium oxide were easily degraded when exposed to UV light. The % removals of toluene and tetradecane at 120 minutes were 84.5 and 98.8 respectively