摘要
本论文致力于纳米钙钛矿型氧化物A(Mg、Ca、Sr)TiO3和另类可见光催化剂钒酸铋的制备、表征和光催化性能的研究。
一、采用溶胶-凝胶法,制备了纳米钙钛矿型氧化物MgTi03、CaTi03、SrTiO3,利用热重-差热(TG-DTA)、X-射线衍射(XRD)、紫外可见分光光度计(UV-Vis)、X-射线光电子能谱(XPS)等分析手段进行了表征。通过光催化降解液相悬浮体系中亚甲基蓝和气相中三氯乙烯,比较了三种钙钛矿型催化剂的光催化活性。结果表明：A位原子不同催化剂晶系结构不同,导致其最佳活性的烧结温度不同,MgTiO3为700℃,CaTiO3、SrTiO3为80℃；其中CaTiO3的光催化活性最佳,原因是CaTiO3光催化剂表面吸附氧能力较强,提供了较多的表面活性物种。
二、采用水相沉淀法,以Bi(N03)3·5H20和NH4VO3为原料,在不同煅烧温度下,制备出具有单一晶相的单斜白钨矿型BiVO4。以亚甲基蓝染料为目标降解物,研究了不同煅烧温度对样品可见光催化活性的影响。同时尝试利用改良的水相沉淀法-熔盐辅助法制备单斜BiVO4,以期望提高其可见光催化活性。结果表明：在不同煅烧温度(300℃、400℃、500℃、600℃)下可以成功制备出具有单一晶相的单斜白钨矿型BiVO4；400℃时制得的样品的可见光催化活性最高；通过熔盐辅助法制得的单斜白钨矿型BiVO4的光催化活性得到了明显的提高,熔盐的投入量对BiVO4的可见光催化活性有着重要影响。
三、采用水相沉淀法,以Bi(NO3)。·5H20和NH4VO3为原料,在低温条件下制备出具有单一晶相的四方白钨矿型和单斜白钨矿型BiVO4,研究了pH对样品的结构和可见光催化活性的影响。结果表明：采用水相沉淀法,在室温下能够制得单一晶相的四方白钨矿型BiVO4,而在110℃下能够制得单斜白钨矿型BiVO4;pH值在低温合成过程中影响着样品的晶型,过酸或过碱条件都不利于单斜相的形成；110℃C条件下,pH=7时样品的光催化活性最高,原因主要是其具有较小的晶粒尺寸和较强的表面吸附氧能力。
该项研究通过研究钙钛矿型氧化物A(Mg、Ca、Sr)Ti03结构及其光催化性能,为AB03钙钛矿型复合氧化物光催化剂中,A位金属对其结构及催化性能所起的作用提供了一定的基础理论数据；采用水相沉淀法在低温条件下成功制备出BiV04的两种纯相,优化了可见光响应的高活性BiVO4的低温制备条件,开拓了BiV04材料的应用途径。为开辟与可见光相匹配的光催化剂的研究与应用以及开发利用绿色光源-太阳能的研究打下一定基础。
This paper were committed to study preparation, characterization and photocatalytic properties of nanometer perovskite oxide A(Mg, Ca, Sr)TiO3 and another visible-light photocatalyst vanadate bismuth.
Firstly, Nanometer perovskite-type oxides MgTiO3, CaTiO3, SrTiO3 were prepared by sol-gel method. The samples were characterized by thermogravimetry-differential thermal (TG-DTA), X-ray diffraction (XRD), UV-Vis spectrophotometer (UV-Vis) and X-ray photoelectron spectroscopy (XPS). Through the photocatalytic degradation of methylene blue and TCE, photocatalytic activity of the three perovskite-type catalysts was compared. The results showed that different atoms at A metal lead to different crystal structure, and different crystal structure resulted in different temperature of optimum activity. The temperature of best photocatalytic activity for MgTiO3 was 700℃, CaTiO3 and SrTiO3 were 800℃. In the above mentioned catalyst, CaTiO3 had the highest photocatalytic activity. The reason was that CaTiO3 photocatalyst had a greater ability of surface adsorbed oxygen, which provided more surface active species.
Secondly, a single crystalline phase monoclinic scheelite type BiVO4 was prepared using Bi(NO3)3·5H2O and NH4VO3 as raw materials by water-phase precipitation method at different calcination temperature. Using methylene blue as a degradation target, we studied that calcination temperature had an impact on visible-light photocatalytic activity of samples. At the same time, molten salt-assisted method was tried to prepare monoclinic BiVO4 to enhance its photocatalytic activity in visible light. The results showed that a single crystalline phase monoclinic scheelite-type BiVO4 was successfully prepared at different calcination temperature(300℃,400℃, 500℃,600℃). The visible-light photocatalytic activity of sample obtained at 400℃was optima. The photocatalytic activity of monoclinic scheelite-type BiVO4 obtained by molten salt-assisted method had been obviously improved, and the amount of molten salt had a significant impact on visible-light photocatalytic activity of BiVO4.
Thirdly, single crystalline tetragonal scheelite type BiVO4 and monoclinic scheelite type BiVO4 were prepared using Bi(NO3)3·5H2O and NH4VO3 as raw materials by water-phase precipitation method at low temperature. We studied that pH had an impact on visible-light photocatalytic activity of samples. The results showed that the tetragonal scheelite-type BiVO4 can be obtained by water-phase precipitation method at room temperature, and the monoclinic scheelite-type BiVO4 can be prepared at 110℃. pH had an impact on the crystalline of samples in the low-temperature synthesis process, and neither too acid nor too alkaline conditions are conducive to the formation of monoclinic phase. In the samples prepared at 110℃under different pH, the photocatalytic activity of sample under pH=7 was the highest. The reason was that it had smaller grain size and greater ability of surface adsorbed oxygen.
It provides a certain theoretical foundation for the role of A metal in ABO3 perovskite structure photocatalyst by studying structure and photocatalytic properties of perovskite-type oxides A (Mg, Ca, Sr) TiO3. Simultaneously, preparation condition of high visible-light activity BiVO4 at low temperature is optimized, and the application path of BiVO4 material is also developed. The paper lays a stone for expanding research of visible light photocatalyst and utilization of green light source-solar energy.
引文
[1]Hoffmann M R, Martin S T, Choi W, et al. Environmental applications of semiconductor photocatalysis. Chemical Review,1995,95:69-96
[2]Jorg Schwitzqebel, J G Ekerdt, H Gerishter, et al. Role of the oxygen molecule and of the photogenerated electron in TiO2-photocatalyzed air oxidation reactions. Journal of Physical Chemistry,1995,99:5633-5638
[3]沈学础,半导体光谱和光学性质.北京：科学出版社,2003
[4]高镰,郑珊,张青红,纳米氧化钛光催化材料及应用.北京：化学工业出版社,2002
[5]A L Linsebigler, G. Q Lu, J T Yates. Photocatalysis on TiO2 Surfaces Principles, Mechanisms, and Selected Results. Chemical Review,1995,95:735-758
[6]张彭义,余刚,蒋展鹏.半导体光催化剂及其改性技术进展.环境科学进,展,1997,5(3)：1-10
[7]于向阳,梁文,程继健.提高二氧化钛催化性能的途径.硅酸盐通报,2000(1)：53-57
[8]张金龙,陈峰,何斌,光催化.上海：华东理工大学出版社,2004
[9]Marta I, Litter. Heterogeneous photocatalysis Transition metal ions in photocatalytic systems. Applied Catalysis B:Environmental,1999,23:89-114
[10]唐玉朝,胡春,王怡中.TiO2光催化反应机理及动力学研究进展.化学进展,2002,14(3)：192-199
[11]Miyamura A, Kaneda K, Sato Y, et al. Effects of internal stress on photocatalytic properties of TiO2 films. Thin Solid Films,2008,516:4603-4608
[12]Arconada N, Duran A, Suarez S, et al. Synthesis and photocatalytic properties of dense and porous TiO2-anatase thin films prepared by sol-gel. Applied Catalysis B:Environmental,2009,86:1-7
[13]Fujishima Akira, Rao T N, Tryk D A. Titanium dioxide photocatalysis. Journal of Photochemistry and Photobiology C:Photochemistry Reviews,2000,1:1-21
[14]刘守新,刘鸿,光催化及光电催化基础与应用.北京：化学工业出版社,2006
[15]Pelizzetti E, Minero C. Metal oxides as photocatalysts for environmental detoxification. Comments of Inorgornic Chemistry,1993,1.5(56):297-299
[16]Zhang W F, Zhang M S, Yin Z, et al. Raman scattering study on anatase TiO2 nanocrystals. Journal of Physics D,2000,33(8):912-916
[17]Maira A J, Yeung K L, Soria J, et al. Gas-phase photo-oxidation of toluene using nanometer-size TiO2 catalysis. Applied Catalysis B:Environmental 2001,29 (4):327-336
[18]Kang M, Lee S-Y, Chung C-H, et al. Characterization of a TiO2 photocatalyst synthesized by the solvothermal method and its catalytic performance for CHCl3 decomposition. Journal of Photochemistry and Photobiology A:Chemistry,2001, 144:185-191
[19]Wu X H, Jiang Z H, Liu H L, et al. Photo-catalytic activity of titanium dioxide thin films prepared by micro-plasma oxidation method. Thin Solid Films,2003, 441(1-2); 130-134
[20]Li X Z, Li F B. Study of Au/Au3+-Ti02 photocatalysts toward visible photooxidation for water and wastewater treatment. Environmental of Science and Technology,2001,35(11):2381-2387
[21]井立强,袁福龙,侯海鸽等.ZnO纳米粒子的表面氧空位与其光致发光和光催化性能的关系.中国科学,B辑,2004,34(4)：310-314
[22]桑丽霞,傅希贤,白树林等.制备方法对LaFeO3及掺杂LaFeO3光催化活性的影响.催化工业与工程,2000,17(6)：336-340
[23]傅希贤,杨秋华,王俊珍等.水溶性染料在LaCoO3体系中的光催化降解.’中国稀土学报,2002,20(6)：589-691
[24]Fu C Y, Chang C, Hsu C S, et al. Electrostatic spray deposition of La0.8Sr0.2Co0.2Fe0.8O3 films. Materials Chemistry and Physics,2005,91 (5):28-35
[25]A. Kudo, S. Hijii。 H2 or O2 Evolution from Aqueous Solutions on Layered Oxide Photocatalysts Consisting of Bi3+with 6s2 Configuration and d0 Transition Metal Ions, Chemistry Letter.1999,28:1103-1113
[26]许效红,姚伟峰,张寅等.钛酸铋系化合物的光催化性能研究.化学学报,2005,63：5-10
[27]Sayama K, Nomura A, Arai T, et al. Photoelectrochemical Decomposition of Water into H2 and O2 on Porous BiVO4 Thin-Film Electrodes under Visible Light and Significant Effect of Ag Ion Treatment. Journal of Physics and Chemistry B,2006,110:11352-11360
[28]Shimodaira Y, Kato H, Kobayashi H, Kudo A. Photophysical Properties and Photocatalytic Activities of Bismuth Molybdates under Visible Light Irradiation. Journal of Physics and Chemistry B,2006,110:17790-17797
[29]He C H, Gu M Y. Photocatalytic activity of bismuth germanate Bi12Ge02o powders. Scripts Mater,2006,54:1221-1225
[30]Zhang C, Zhu Y F. Synthesis of Square Bi2W06 Nanoplates as High-Activity Visible-Light-Driven Photocatalysts. Chemistry Matter,2005,17:3537-3545
[31]Fu H B, Pan C S, W Q, et al. Visible-Light-Induced Degradation of RhodamineB by Nanosized Bi2W06. Journal of Solid State Chemistry B,2005,109: 22432-22439
[32]Tang J W, Zou Z G, Ye J H. Photocatalytic decomposition of organic contaminants by Bi2WO6 under visible light irradiation. Catalysis Letter,2004, 92:1-2
[33]李言荣,恽正中,材料物理学概论.北京：清华大学出版社,2001
[34]曾佳,汪浩,朱满康等.钙钛矿氧化物的化学结构及其催化性能的研究进展.材料导报,2007,21(1)：33-36
[35]康振晋,孙尚梅,郭振平.钙钛矿结构类型的功能材料的结构单元和结构演变.化学通报,2000,4,23-26
[36]李大光,章弘毅,张鹤丰等.钙钛矿型复合氧化物的研究与应用进展.材料导报,2006,20(Ⅵ)：296-299
[37]Yeom Tae Ho, Choh Sung Ho, Du Mao Lu, et al. EPR study of Fe3+impurities in crystalline BiVO4. Physical Review B:Condensed Matter,1996, 53(6):3415-3421
[38]Yeom T H, Rudowicz C, Choh S H, et al. Monoclinic spin Hamiltonian analysis of EPR spectra of Mn2+in BiVO4 single crystals. Physica Status Solid B:Basic Research,1996,198(2):839-851
[39]Man P P, Choh S H, Fraissard J. Application of one-dimensional nutation nuclear magnetic resonance to 51V in ferroelastic BiVO4. Solid state nuclear magnetic resonance,1994,3(4):231-236
[40]Bhattacharya A K, Mallick K K, Hartridge A. Phase transition in BiVO4. Materials Letters,1997,30(1):7-13
[41]Liu JingBing, Wang Hao, Wang Shu, et al. Hydrothermal preparation of BiVO4 powders. Materials Science and Engineering B:Solid-State Materials for Advanced Technology,2003, B104(1-2):36-39
[42]Yu Jianqiang, Kudo Akihiko. Hydrothermal synthesis of nanofibrous bismuth vanadate. Chemistry Letters,2005,34(6):850-851.
[43]菅盘铭,夏亚穆,李德宏等.掺杂TiO2纳米粉的合成、表征及催化性能研究. 催化学报,2001,22(2)：161-164.
[44]Shantha K, Varma K B R. Preparation and characterization of nanocrystalline power of bismuth vanadate. Matter Science and Engineering B,1999,60:66-75
[45]Lin Zhou, Wenzhong Wang, Shengwei Liu, et al. A sonochemical route to visible-light-driven high-activity BiVO4 photocatalyst. Journal of Molecular Catalysis A:Chemical,2006,252:120-124
[46]Jianqiang Yu, Yan Zhang, Akihiko Kudo. Synthesis and photocatalytic performances of BiVO4 by ammonia co-precipitation process. Journal of Solid State Chemistry,2009,182:223-228
[47]Saimi Tokunaga, Hideki Kato, Akihiko Kudo. Selective Preparation of Monoclinic and Tetragonal BiVO4 with Scheelite Structure and Their Photocatalytic Properties. Chemistry Matter,2001,13:4624-4628
[48]K Shantha, K B R Varma. Preparation and characterization of nanocrystalline powders of bismuth vanadate. Materials Science and Engineering B,1999,56:66-75
[49]Xi Zhang, Zhihui Ai, Falong Jia, et al. Selective synthesis and visible-light photocatalytic activities of BiVO4 with different crystalline phases. Materials Chemistry and Physics,2007,103:162-167
[50]Kudo Akihiko, Omori Keiko, Kato Hideki. A Novel Aqueous Process for Preparation of Crystal Form-Controlled and Highly Crystalline BiVO4 Powder from Layered Vanadates at Room Temperature and Its Photocatalytic and Photophysical Properties. Journal of the American Chemical Society,1999, 121(49):11459-11467
[51]孙尚梅.钙钛矿型复合氧化物纳米晶的合成、表征及其催化性质研究：[硕士学位论文].长春：吉林大学,2007
[52]Yang Yang, Yanbin Sun, Yinshan Jiang. Structure and photocatalytic property of perovskite and perovskite-related compounds. Materials Chemistry and Physics,2006,96:234-239
[53]Sebastien Royer, Francois Berube, Serge Kaliaguine. Effect of the synthesis conditions on the redox and catalytic properties in oxidation reactions of LaCo1-χFeχO3. Applied Catalysis A:General,2005,282:273-284
[54]Loic Marchin, Sophie Guillemet-Fritsch, Bernard Durand. Soft chemistry synthesis of the perovskite CaCu3Ti4O12. Progress in Solid State Chemistry,2007,36:151-155
[55]S.Guntuka, S.Banerjee, S.Farooq, et al. A-and B-Site substituted lanthanum cobaltite perovskite as high temperature oxygen sorbent.1.thermogravimetric analysis of equilibrium and kinetics. Industrial and Engineering Chemistry Research,2008,47:154-162
[56]Rei Fujiwara, Hiroyuki Sano, Mikio Shimizu, et al. Quantitative analysis of UV excitation bands for red emissions in Pr3+-doped CaTiO3, SrTiO3 and BaTiO3 phosphors by peak fitting. Journal of Luminescence,2009,129:231-237
[57]Tetsuya Kako, Naoki Kikugawa, Jinhua Ye. Photocatalytic activities of AgSbO3 under visible light irradiation. Catalysis Today,2008,131:197-202
[58]Zhaosheng Li, Tao Yu, Zhigang Zou, et al. Degradation in photocatalytic activity induced by hydrogen-related defects in nano-LiNbO3 material. Applied Physics Letters,2006,88:071917
[59]孙尚梅,庞广生,李春光,等.熔盐中熟化处理提高BiFeO3的可见光催化活性.高等学校化学学报,2007,28(10)：1830-1832
[60]Haitao Zhang, Shuxin Ouyang, Zhaosheng Li, et al. Preparation, characterization and photocatalytic activity of polycrystalline Bi2O3/SrTiO3 composite powders. Journal of Physics and Chemistry of Solids,2006,67:2501-2505
[61]Wang Xuewen, Zhang Zhiyong, Zhou Shuixian. Preparation of nano-crystalline SrTiO3 powder in sol-gel process. Materials Science and Engineering B,2001, 86:29-33
[62]沈伟韧,赵文宽,贺飞等.TiO2光催化反应及其在废水处理中的应用.化学进展,1998,10(4)：349-361
[63]Marta I, Litter. Heterogeneous photocatalysis Transition metal ions in photocatalytic systems. Applied Catalysis B:Environmental,1999,23:89-114
[64]田蒙奎,上官文峰,欧阳自远等.光解水制氢半导体光催化材料的研究进展.功能材料,2005,10(36)：1489-1500
[65]余家国,赵修建,赵青南,杜金成.TiO2光催化薄膜的XPS研究.材料研究学报,2004,14(2)：203-209