Preparation of Ultra-Thin-Film Anchored Metal Oxide Catalysts Via Laser Excitation and Their Photocatalytic Activities

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Anchoring of VOC1_3 onto porous Vycor glass and silica was performed using a facile reaction of photoactivated VOC1_3 with surface OH groups of the dehydrated Vycor glass and silica at 273 K. Photoactivation of adsorbed VOC1_3 molecules was carried out by a N_2 laser excitation of VOC1_3 (Photo-CVD). The number of anchored VOC1_3 and reacted surface OH groups was monitored by UV and IR spectroscopy. Anchored samples were evacuated, hydrolyzed with H_2O, and finally calcined in O_2. It was found that photochemically anchored vanadium species were transferred to tetrahedrally coordinated ultra-thin-film anchored vanadium oxide.Ultra-thin-film anchored vanadium oxide catalysts exhibited much higher reactivities for the various photocatalytic reactions than those of the vanadium oxides prepared by conventional impregnation method. UV irradiation of ultra-thin-film anchored vanadium oxide in the presence of trans-2-butene led to the photocatalytic isomerization, the formation of cis-2-butene and 1-butene. It was first found that UV irradiation of ultra-thin-film anchored vanadium oxide at 275 K in the presence of NO led to the direct decomposition of NO into N_2 and O_2. It was also found that UV irradiation of ultra-thin-film anchored vanadium oxide in the presence of a mixture of NO and CH_4 led to the oxidative coupling reaction of CH_4, resulting in the formation of C_2H_6, C_2H_4, and CH_3OH.Thus, the present research project not only provided useful information on the advantage of the laser-excitation processes to prepare the ultra-thin-film anchored vanadium oxide but also showed the high photocatalytic activities of the photo-chemically prepared ultra-thin anchored vanadium oxide forvarious reactions at normal temperature.