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Oxidation of TiO or Ti2O3 led to the formation of TiO2 with activity in visible light much higher than when TiN was used as a precursor, pointing out the importance of oxygen defects/vacancies for extension of activity of TiO2 into the visible region.

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Titania-supported mesoporous materials are evoking interest in the field of photocatalysis. [1] In particular, transitionmetal-ion-containing MCM-41-supported TiO 2 photocatalysts have been studied for the degradation of pollutants. [2][3][4] However, MCM-41 has a unidirectional pore system and this type of pore arrangement restricts the transport of products and reactants. MCM-48 possesses a continuous three-dimensional (3D) pore system that provides favorable mass-transfer kinetics and seems to be a more attractive candidate for catalytic applications. There is no report to date of a single-step synthesis for the preparation of a visible-light, transition-metal-ion-containing MCM-48-supported TiO 2 photocatalyst.The Ti-Cr-MCM-48 photocatalyst prepared in a single step exhibits far superior photocatalytic activity compared to the TiO 2 -Cr-MCM-48 prepared by a post-impregnation method. The high activity of the Ti-Cr-MCM-48 photocatalyst is attributed to a synergistic interaction between Cr ions dispersed in the silica framework and the nanocrystalline nature of titania crystallites anchored onto the pore walls.Treatment of polluted air by catalytic techniques is a wellestablished process. Catalytic combustion processes require temperatures of 473-1473 K for efficient operation and hence are energy intensive. Furthermore, these traditional methods of treatment are not economically feasible at low pollutant concentrations. There is a need for an ambient temperature catalytic process that can carry out complete detoxification of air pollutants at low levels. Hence, extensive research is underway in this area. Acetaldehyde is a common indoor air pollutant, emitted from incomplete combustion from fireplaces, and consumer products such as adhesives, nail polish, etc.Photocatalysis has attracted the attention of research scientists for several years. [5,6] Titanium dioxide is one of the most widely studied photocatalysts. [7,8] A common approach to enhance the photocatalytic activity of TiO 2 is to use supported TiO 2 catalysts. Herrmann and co-workers [9] and Xu and Langford [1,10] have shown that nanometer-sized titania on a highsurface-area support produces higher quantum yields than pure titania. The discovery of mesoporous materials has attracted the attention of many research workers. [11,12] Transition-metal-incorporated mesoporous materials have been extended for use as photocatalysts. [13][14][15][16] Smirniotis and co-workers [2][3][4] have reported the photodegradation of organics using TiO 2 -loaded Cr-incorporated MCM-41. However, the catalysts employed in their studies were prepared by a two-step process and the preparation of such titania-loaded transition-metal-containing MCM-41 photocatalysts typically took at least 4 days if not more. The loading of titania was carried out by impregnation, which led to partial breakage of the tubular walls of the MCM-41, resulting in a decrease in surface area. Thus, there is a need for shortening the time of synthesis of titania-supported mesoporous materials while k...

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