掺杂Fe^(3+)的A-TiO_2可见光照射下催化降解甲醛研究

采用水热法制备了掺Fe^(3+)的A-TiO_2粉末,研究了其在可见光照射下催化降解甲醛的效果。结果表明,在3.7 mg/L的甲醛溶液中,加入自制的掺杂0.4%Fe^(3+)的A-TiO_2粉末(用量为0.108 g/L),35℃下可见光(95 W白炽灯)照射2 h,甲醛降解率达到55.62%。

可见光下掺Fe^(3+)A-TiO_2粉体对茜素红的催化降解

用水热法制备了(掺杂)TiO_2粉体试样,利用红外光谱仪(FT-IR)、X射线衍射(XRD)和扫描电子显微镜(SEM)对产物进行了表征。探索在可见光下用(掺杂)TiO_2催化降解茜素红的效果,研究茜素红初始浓度、pH、催化剂用量、掺Fe^(3+)量、光照时间等因素的影响。结果表明:试样中出现3400、1636 cm^(-1)的吸收峰,说明它含有大量—OH;粉体为锐钛矿型即为A-TiO_2;试样由诸多细小的纳米晶定向聚集生成,八面体型纳米晶呈现复杂3D花状结构,花状结构的直径2.5μm左右,纳米晶体的长度1～1.5μm,形成八面体晶体的三角形边长100～200 nm;TiO_2光催化降解茜素红的最佳条件:茜素红溶液初始浓度1.5 g·L^(-1)、调节溶液的pH为4.0、自制掺Fe^(3+)量5%(摩尔分数)的A-TiO_2用量0.502 g·L^(-1)、恒温14℃、60 W白炽灯,光照时间45 min,茜素红降解率87.22%。用自创技术制备的掺杂TiO_2粉体有较高的光催化性能。

Mechanism and behaviors of Cr3+-doped TiO2

TiO2 powder and TiO2 thin film on the surface of glazed ceramic tile were prepared by sol-gel method.The influences of different doping Cr3+ concentration on the photocatalytic activity of TiO2 were discussed, UV-visible and X-ray diffraction analysis were used to test the performance of TiO2 powder and film. The results indicate that photocatalytic activity of doping Cr3+-TiO2 thin film is higher than that of powder, and the interaction between Cr3+-doped and substrate can greatly enhance the photocatalytic activity. The results of X-ray diffraction and photoabsorption show that the Cr3+ -doped energy level in TiO2 is 0. 62 eV high from the top of valence band, which belongs to the type of deep energy level doping. On the basis of the semiconductor energy level theory and Cr3+ dopant energy level, the semiconductor energy level model of Cr3+ in TiO2 powder and thin film were established, and the doping mechanisms of Cr3+-doped in TiO2 powder and thin film were analyzed.

Emission property of Y_2O_3-doped Mo secondary emitter

Y2O3-doped Mo secondary emitters were prepared by liquid-liquid doping and solid-solid doping,respectively.The back-scattered scanning observation result indicates that the emitter prepared by liquid-liquid doping has fine microstructure whereas that prepared by solid-solid doping has large grain size.Y2O3-doped Mo emitter with small grain size prepared by liquid-liquid doping exhibits high emission property,i.e.,the secondary electron yield can get to 5.24,about 1.7 times that prepared by solid-solid doping.Moreover,Y2O3-doped Mo emitter exhibits the best emission performance among La2O3-doped Mo,Y2O3-doped Mo, Gd2O3-doped Mo and Ce2O3-doped Mo emitters due to the largest penetration depth of primary electrons and escape depth of secondary electrons in this emitter.The secondary emission of the emitter with small grain size can be explained by reflection emission model and transmission emission model,whereas only transmission emission exists in the emitter with large grain size.

掺Fe3+改性A-TiO2的合成及其对曙红的可见光催化降解性能

采用水热法合成了系列含不同掺Fe^3+量的改性TiO2 粉末( 1^x , x=0、 2、 4、 5、 6、 8,掺铁量分别为0、 2 mol%、 4 mol%、 5 mol%、 6 mol%和8 mol%),其结构和形貌经XRD和SEM表征。并研究可见光照下 1x 对曙红降解的催化效果,考察了不同因素的影响和光催化剂对曙红的暗吸附性能。结果表明: 1 x 的晶体为单一锐钛矿型(A-TiO2 ),由直径2~3 μm的 1x 微米球堆积而成;在15 mg·L^-1 曙红溶液(pH=4)中, 15 投放量为7 g·L^-1 ,于室温(18 ℃)可见光(功率40 W的白炽灯)照射反应3 h,曙红降解率 D 最大(63.1%),在该光催化优化条件下进行暗吸附,1.5 h达到吸附平衡, 1 5 对曙红吸附量为1.01 mg·g^-1 。

掺Fe3+A-TiO2紫外光下催化降解乙基紫

以掺Fe^3+A-TiO2粉末为催化剂对乙基紫溶液进行光催化降解,并确定降解的最佳条件,同时开展了暗吸附研究。结果表明,乙基紫溶液的起始质量浓度为10mg/L(溶液自身pH=6),加入2g/L掺Fe^3+5%(摩尔比)的A-TiO2粉末,在室温下(20℃)经254nm的紫外光照射,恒温快速搅拌反应1.5h,乙基紫降解率为33.70%。同上条件下撤去光源进行暗吸附试验,2h达到吸附平衡,催化剂对乙基紫吸附量为1.472mg/g。

Effects of annealing temperature and neodymium concentration on structural and photoluminescence properties of Nd^(3+)-doped Y_(2)O_(3)-SiO_(2) powders

We report the structural and photoluminescence(PL) properties of Nd^(3+)-doped Y_(2)O_(3)-SiO_(2) powders(Y_(2)O_(3)-SiO_(2):Nd^(3+)) as functions of annealing temperature and Nd^(3+) ion doping concentration.Y_(2)O_(3)-SiO_(2):Nd^(3+)powders were prepared using the high-energy ball-milling(HEBM) method,and their structural and PL properties were investigated using X-ray diffraction(XRD),Fourier transform infrared(FTIR) spectroscopy,and PL spectroscopy.The XRD results reveal a cubic phase without impurities,and the peak broadening decreases with an increase in annealing temperature due to the increase in the crystallite size.The PL emission intensity increases with an increase in annealing temperature.The highest PL emission intensity is observed for the 300-min milled mixture annealed at 1000℃ for 1 h with a Nd^(3+) concentration of 1 mol%.The PL peaks excited by 800 nm radiation were detected,centered at 1080 nm(^(4)F_(3/2)→^(4)I_(11/2)) and 1350 nm(^(4)F_(3/2)→^(4)I_(13/2)).