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

在273 K下，利用光活化的VOCl_3与脱水的Vycor玻璃和二氧化硅表面的OH基团的简单反应，将VOCl_3负载到多孔Vycor玻璃和二氧化硅上。用N_2激光激发VOC1_3（Photo-CVD），对吸附的VOC1_3分子进行光活化。通过紫外和红外光谱监测锚定的VOC 1_3和反应的表面OH基团的数量。锚定样品抽真空，H_2O水解，最后在O_2中煅烧。结果表明，光化学锚定的钒物种被转移到四面体配位的超薄膜锚定的钒氧化物上，超薄膜锚定的钒氧化物催化剂对各种光催化反应的活性远高于传统浸渍法制备的钒氧化物。在反式-2-丁烯存在下，紫外光照射超薄膜锚定氧化钒导致光催化异构化，生成顺式-2-丁烯和1-丁烯。首次发现在275 K紫外光照射下，NO直接分解为N_2和O_2。研究还发现，在NO和CH_4混合气体存在下，紫外光照射超薄膜锚定的氧化钒，导致CH_4发生氧化偶联反应，生成C_2H_6、C_2H_4和CH_3OH，从而导致氧化钒的氧化还原。目前的研究项目不仅提供了有用的信息，激光激发过程的优势，以制备超薄，光化学法制备的超薄锚定氧化钒不仅在常温下对各种反应都表现出很高的光催化活性，

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.