Microstructural Engineering of metal-titania catalysts(2/2)
|Authors:||吳乃立||Keywords:||二氧化鈦;氫生成;光觸媒催化;煅燒氣氛;Ar;銅;Titania;hydrogen production;photocatalysis;calcination atmosphere;Ar;Cu||Issue Date:||20-Oct-2003||Publisher:||臺北市：國立臺灣大學化學工程學系暨研究所||Abstract:||
由溶膠-凝膠法製成後於Ar, 合成空氣(air)，氮(N2), 氫(H2 3% in N2) and 真空(vacuum;~5 x 10 -3
torr) 。對於由甲醇水溶液中形成氫之活性高低次序為Ar > air> N2 > vacuum ~ H2 。光譜分析顯示
TiO2 photocatalysts for hydrogen production from aqueous methanol solution is the main subject of this work, Studies on two issues are reported here, including (1) the effect of calcination atmosphere and (2) the effect of Cu metallization. TiO2 catalysts were synthesized by a sol-gel process followed by calcination at 400 o C in Ar, air, N2, H2 (3% in N2) and vacuum (~5 x 10 -3 torr), respectively. Toward H2 production from a water/methanol (vol. ratio= 1.4/1) solution, the catalysts exhibited activities in the order, according to calcination atmosphere, of Ar > air> N2 > vacuum ~ H2. The low activity resulting from either vacuum or H2 calcination was ascribed to a reduced coverage of surface hydroxyl and high bulk defect density, based on the x-ray photoelectron and UV-visible spectroscopic analyses, while the high activity from Ar calcination is to enhanced visible-light excitation. For studying the effect of Cu, Cu particles have been deposited on TiO2 by incipient-wetness impregnation followed by low-temperature (400 o C) calcination/reduction, and the metallization process leads to significant, up to 10 folds, enhancement in photocatalytic activity of TiO2 for H2 production from aqueous methanol solution. Spectroscopic studies indicated that the metallic Cu particles were oxidized to have an optimum valence that can not be achieved by thermal oxidation. Dissolution of Cu ion in TiO2 lattice, in contrast, led to reduction in the activity.
|Appears in Collections:||化學工程學系|
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