Preparation, Characterization and Visible Light Photocatalytic Activity of Nitrogen-doped TiO2

The N-doped TiO2 polycrystalline powder was synthesized through calcining the hydrolysis prodact of tetra-butyl titanate with ammonia. The photocatalytic activity of N-doped TiO2 powder with anatase phone calcined at 400℃ was 2.7 times higher than that of Degussa P25 for phenol decomposition under visible light. All samples had mesoporoas structures. X- ray photoelectron spectroscopy confirmed that a trace amount of N atoms remained in the anatase polycrystaUine TiO2 powder when calcined at 400 ℃ as substitutional atoms at the oxygen sites. UV-Vis and EPR analyses indicated that oxygen vacancy states were created during the course of N-doped TiO2 powder formation. It is considered that substitutional N atoms, oxygen vacancy, states, large BET surface areas and mesoporoas structure are important facwrs for the N-doped photocatalyst to present a high vis-activity.     

TiO_2-SiO_2复合气凝胶涂层的制备和光催化性能

利用TiCl4和工业水玻璃为原料,通过溶胶凝胶法制备TiO2-SiO2复合凝胶,用三甲基氯硅烷(TMCS)/乙醇(EtOH)/正己烷(Hexane)混合溶液对湿凝胶进行改性,常压干燥制备了TiO2-SiO2气凝胶,经150℃干燥所得的气凝胶具有多孔结构,获得的气凝胶比表面积达到646～816m2/g,孔体积达到1.52～2.19cm3/g。用乙醇作为分散剂,将气凝胶块体研磨成具有一定黏度的浆料,采用丝网印刷法制成TiO2-SiO2复合气凝胶涂层。利用X射线衍射(XRD)、扫描电镜(SEM)和孔径及比表面积分析仪(BET)对复合气凝胶的结构、形貌和孔性质进行了研究,通过分光光度计法分析了TiO2-SiO2复合气凝胶涂层光催化降解罗丹明B的性能,在可见光下照射4h后降解率达到77%。     

Microstructure evolution of graphite intercalated by TiO2 and its photocatalytic activity

An intercalative composite of graphite oxide (GO) as host intercalated by an object of TiO₂ nanoparticles was obtained at low temperature by mixing GO with Ti(SO₄)₂ solution, and by another object of Ti₂O₃ while mixing with TiCl₄ ethanol solution. Microstructures of the GO and its intercalative composites at different C/Ti ratio were studied by XRD, SEM, AFM and FT-IR, and the evolution of these lamellar structures was studied based on the temperature change. The photocatalytic activity of the intercalative composites was characterized according to the degradation of methyl orange. The intercalative composite formed by Ti(SO₄)₂ solution presents an excellent photocatalytic reactivity, while that formed by TiCl₄ presents no observablly photocatalytic reactivity. The electric conductivity variation of different composites was checked, in order to investigate the role of the possible electron transfer between the graphite layer and TiO₂ nanocrystal during TiO₂ excited by UV light irradiation. Funded by The National Natural Science Foundation of China (No.50572070 and No.50672066)     

Preparation and photocatalytic activity of Gd-doped TiO2 nanofibre

In order to realize the photocatalysis of TiO2 in the sunlight and directly apply it to waste water treatment, the Gd-doped TiO2 nanofibre was synthesized using two-step synthesis method as follows： Firstly, potassium carbonate, titanium dioxide and proper gadolinium oxide （dopant） were calcined in the muffle at high temperature and the doped gadolinium K2Ti4O9 fibres were obtained; secondly, the fibre was heated using glycerol as solvent until Gd-doped TiO2 nanofibres were obtained. The synthesized samples were characterized using scanning electron microscopy, transmission electron microscopy and X-ray diffraction. The results show that Gd-doped TiO2 nanofibre heat-treated by glycerol solvent can inhibit the agglomeration, so the grain diameter of the fibre is smaller than that without heat-treated with glycerol. Meanwhile, the diameter of the fibre decreases with the increase of the heating temperature and time. 97%- 98% of Gd-doped TiO2 nanofibre is anatase. The photocatalysis results showed that the photocatalysis activity of Gd-doped TiO2 nanofibre is just a little lower than that of TiO2 powder.     

钇掺杂TiO2形态结构表征及光催化活性研究

以溶胶一凝胶法制备了钇（Y）掺杂的TiO2,采用SEM、EDS、BET、XRD等测试手段对其进行了表征．XRD分析结果表明钇掺杂的TiO2具有锐钛矿型结构;SEM观察发现该催化剂表面有大量孔,平均粒径为10～20nm;EDS测试表明Y在TiO2中分布均匀;BET测试结果表明掺杂钇后,催化剂比表面积由原来的49．03m^2／g增加到99．43m^2／g;通过对甲基橙的光催化降解测试证明Y掺杂的TiO2的催化效率比纯TiO2有很大提高,90min时降解率达到85％,比纯TiO2降解效率提高40％．实验还表明Y掺杂的TiO2对可见光的响应活性比纯TiO2有一定提高．     

玻璃基TiO2/(Cu,Al)复合薄膜可见光活性影响因素研究

以钛酸四丁酯、硝酸铜和硝酸铝为先驱原料,乙醇为溶剂,二乙醇胺为稳定剂制备了玻璃基TiO2/(Cu,Al)复合薄膜.采用XRD、SEM和分光光度计研究了薄膜焙烧温度对复合薄膜晶相组成、形貌以及可见光催化活性的影响,采用UV-Vis分光光度计表征了混合离子加入量对复合薄膜光谱响应的影响规律.结果表明,掺杂混合离子的TiO2复合薄膜在450 ℃即可开始形成锐钛矿相,直至600 ℃一直保持锐钛矿相,表现出很好的晶体结构稳定性,而纯TiO2薄膜550 ℃焙烧时即出现金红石相;SEM晶相结构显示550 ℃焙烧的复合薄膜晶体形成均匀,致密,对基片覆盖率高,相应的可见光催化活性也最高;随着混合离子加入量的增加,光谱响应吸收边不同程度地红移至可见区,尤以掺杂量n=2 mol的Ti100-x/CuxAl2x复合薄膜吸收边红移最大(较纯TiO2薄膜大约红移75 nm).光催化实验表明,复合薄膜的可见光活性显著提高,掺杂量n=2 mol的Ti100-n/CunAl2n复合薄膜对酸性红B的降解脱色率可达67.3%,比纯TiO2的降解脱色率(5.5%)提高了近12倍.     

TiO2／沸石微粒的制备及其光降解甲基橙的性能研究

以钛酸丁酯为钛源,180目天然沸石为载体,用溶胶-凝胶-浸渍法制备了不同涂膜层数的TiO2／沸石微粒光催化剂,用X射线衍射和红外光谱对其进行了表征．以甲基橙为目标降解物,在光照强度、甲基橙初始浓度、催化剂投加量与空气通入量一定的光催化反应器中,通过30min光催化降解的吸光度变化,考察了TiO2涂膜层数、催化剂重用性能等不同条件下催化剂的光催化活性．结果表明,涂覆5层、120℃下干燥12h、200℃煅烧2h时的TiO2／沸石微粒对沸石结构没有影响,TiO2与沸石间形成了较强的Ti-O-Si化学键合,光催化活性最高,投加1．0mLH2O2,重复使用4次后再生,其光催化活性由59．35％恢复至82．3％．     

表面修饰Ru的TiO2纳米粒子的表征及其光催化活性

采用sol—gel法以600℃热处理的TiO2纳米粒子为载体,通过浸渍法在不同温度焙烧下制备了表面修饰质量分数为4％Ru的TiO2样品,并利用XRD、XPS和FS光谱等手段对样品进行表征,分析了焙烧温度对TiO2样品发光性质和光催化降解苯酚活性的影响,并探讨FS光谱强度与光催化活性的内在关系以及改性机制．结果表明,Ru物种均匀地分布在TiO2样品表面,且能够使FS光谱强度下降．焙烧温度升高,FS光谱强度下降;不同温度处理的表面修饰Ru的TiO2样品的光催化活性顺序是：600℃〉450℃〉300℃〉100℃,与它们的FS光谱强度的顺序相反,即FS光谱强度越低,其光催化活性越高．     

Au改性TiO2纳米粒子的制备及其光催化活性

以自制的TiO：纳米粒子为前驱物,利用浸渍法制备了表面修饰Au的TiO2纳米粒子,并利用TGDTA、XRD和TEN等手段对样品进行了表征．以光催化降解苯酚为模型反应,考察了焙烧温度和表面修饰Au的量对Au／TiO2纳米粒子光催化活性的影响．结果表明：Au以原子簇形式沉积在TiO2纳米粒子表面;在实验条件下,表面修饰量ω(Au)=0．5％,焙烧温度为500℃时,Au／TiO2纳米粒子样品具有最佳的光催化活性．     

离子掺杂和氢气氛处理对TiO2光催化性能的影响

研究了过渡金属离子、稀土金属离子或N、C阴离子对TiO2掺杂,以及在氢气氛条件下处理TiO2,使其具有可见光光催化活性.过渡金属离子掺杂,可在TiO2晶格中引入缺陷,促进电子-空穴的分离或复合;稀土金属掺杂有利于提高TiO2的光催化活性,光催化活性的增加可能是由于稀土金属掺杂,增加了TiO2对污染物的吸附、促进了TiO2红移到较高的波长,以及其表面电子迁移速率的增加阻止了电子-空穴复合;C、N阴离子掺杂或在氢气氛条件下对TiO2进行处理,可能会产生TiO2-xCx、TiO2-xNx、TiO2-x等半导体,晶体颜色由浅变深,促进对光吸收波长的红移,有利于可见光催化活性的提高.     

离子掺杂和氢气氛处理对TiO2光催化性能的影响

研究了过渡金属离子、稀土金属离子或N、C阴离子对TiO2掺杂,以及在氢气氛条件下处理TiO2,使其具有可见光光催化活性．过渡金属离子掺杂,可在TiO2晶格中引入缺陷,促进电子一空穴的分离或复合;稀土金属掺杂有利于提高TiO2的光催化活性,光催化活性的增加可能是由于稀土金属掺杂,增加了TiO2对污染物的吸附、促进了TiO2红移到较高的波长,以及其表面电子迁移速率的增加阻止了电子一空穴复合;C、N阴离子掺杂或在氢气氛条件下对TiO2进行处理,可能会产生TiO2-xCx、TiO2-xNx、TiO2-x,等半导体,晶体颜色由浅变深,促进对光吸收波长的红移,有利于可见光催化活性的提高．     

纳米粒子TiO2/Ti膜的制备及其光催化活性

以钛酸四丁酯为原料，利用溶胶－凝胶方法制备了纳米粒子TiO2/Ti膜。TG－DTA、XRD、TEM和SEM的测试表明：纳米粒子经历了无定型向锐钛矿和锐钛矿向金红石相转变两个过程，而焙烧温度为600℃时，TiO2纳米粒子具有与国际商品P－25型TiO2粒子相类似的组成、结构、形貌和粒子尺寸。考虑TiO2粒子性质及与基体Ti片的结合能力，焙烧温度对基体Ti片的影响和纳米粒子TiO2/Ti膜表面形貌等因素，确定600℃是制备纳米粒子TiO2/Ti膜光催化剂的最合适的焙烧温度。另外，以光催化降解苯酚为模型反应，考察了焙烧温度对纳米粒子TiO2/Ti膜催化活性的影响，并初步地探讨了光催化降解苯酚反应的动力学。结果表明，600℃焙烧的TiO2纳米粒子膜具有最高的光催化活性，而光催化降解反应为准一级动力学反应。     

铋掺杂磁性光催化剂的制备及其光催化活性

以Fe3O4/SiO2复合微球为基体,采用溶胶—凝胶法制备了Bi掺杂的磁性TiO2复合光催化剂,并用SEM、FT—IR和VSM等测试手段对催化剂进行了表征。以活性艳红K-2BP为目标降解物评价其光催化活性。结果表明,制备的复合光催化剂易于磁性固液分离,K-2BP溶液初始浓度为20 mg/L,pH值为2,光催化剂的添加量为0.5 g/L,Bi摩尔分数为0.6%的光催化剂时的催化活性最高,光催化反应5 h后K-2BP的降解率达到88.38%。     

Fe3+掺杂TiO2玻璃薄膜太阳光催化降解H酸的研究

采用溶胶-凝胶法在玻璃表面上制备了掺杂Fe3+的TiO2薄膜,用XRD、IR对其进行表征.在太阳光的照射下,以H酸为目标物,用自制敞开连续流平板式光催化反应器,进行了光催化法降解试验.结果表明:适量Fe3+的掺杂可明显提高TiO2玻璃薄膜在太阳光下的催化性能,掺Fe3+的摩尔质量百分数为(Fe3+/TiO2)0.06%时的光催化活性最高.太阳光照射3 h,H酸脱色率达到72.5%,反应速率遵从Langmuir-Hinshelwood方程,表观速率常数K′=0.007 4 min-1.     

水热法制备海绵钛负载二氧化钛膜及性能研究

以多孔海绵钛为载体,2 mol/L H2O2为氧化剂,0.15 mol/L KOH为矿化剂,在水热条件下一步合成了颗粒大小约为0.5 μm的四方状锐钛矿海绵钛负载TiO2膜.以XRD、SEM观察海绵钛负载TiO2膜晶型、形貌,以亚甲基蓝为目标降解物研究了其光化性能催化,并探讨了水热时间对产物TiO2膜晶型、形貌及光催化性能的影响.结果表明,12 h为最佳水热时间,海绵钛负载TiO2膜有着最佳的光催化性能:光催化反应60 min,亚甲基蓝溶液的降解率达99%.采用该法制备的TiO2光催化剂回收简单,反复利用后,其光催化性能无明显下降.     

蝶翅结构多孔二氧化钛的制备与光催化性能研究

自然界天然存在的多孔结构被证明可以有效增加材料的光捕获效率。为了提高二氧化钛的光捕获效率从而进一步提高其光催化性能,采用生物模板的浸渍-焙烧脱模法制备了具有绿带翠凤蝶典型鳞片结构的二氧化钛(TiO₂),在对其微观结构进行了表征的基础上研究了其光捕获与光催化降解结晶紫性能。研究结果表明,所制备的二氧化钛能较好地复制了原始蝶翅的具有粗糙纹理的倒V型脊结构和纳米多孔阵列。这种具有蝶翅分级多孔结构的二氧化钛通过对光线的反复有序的散射和折射,有效地增强了光捕获效率,进而获得了优于普通二氧化钛的光催化性能。     

UV/TiO2 and UV/TiO2-film for Degradation of Textile Dyes

Wastewaters fromtextile and dyeingindustries are highly colored by various non-biodegradable dyes whichcause serious environ-mental problems[1].The effluents of the wastewater introduced not only color but alsotoxicityinto aquatic system.The conventionalt…     

Formation of active radicals and mechanism of photocatalytic degradation of phenol process using eosin sensitized TiO2 under visible light irradiation

The role of oxygen and the generation of active radicals in the photocatalitic degradation of phenol were investigated using the eosin sensitized TiO2 as photocatalyst under visible light irradiation. Diffuse reflectance spectra show that the absorbancy range of eosin/TiO2 is expanded from 378 nm (TiO2 ) to about 600 nm. The photocatalitic degradation of phenol is almost stopped when the eosin/TiO2 system is saturated with N2 , which indicates the significance of O2 . The addition of NaN 3 (a quencher of single oxygen) causes about a 62% decrease in the phenol degradation. The phenol degradation ratio is dropped from 92% to 75% when the isopropanol (a quencher of hydroxyl radical) is present in the system. The experimental results show that there are singlet oxygen and hydroxyl radical generated in the eosin/TiO2 system under visible light irradiation. The changes of absorbancy indicate that the hydrogen peroxide might be produced. Through the analysis and comparison, it is found that the singlet oxygen is the predominant active radical for the degradation of phenol.     

载银TiO2/沸石催化剂的制备、表征以及光催化性能的研究

为获得高活性的负载型TiO2光催化剂，通过硝酸银溶液浸渍-紫外光照的方法获得载银的TiO2/沸石催化剂.银改 性的TiO2/沸石催化剂光催化性能较改性前大大提高.最佳硝酸银浸渍液浓度为10-3mol/L,此时该催化剂的光催化性能接 近纳米TiO2粉末（Degussa P25）,但进一步升高硝酸银浸渍液浓度，光催化性能又降低.实验通过X-射线衍射（XRD）和 透射电镜（TEM）对载银TiO2/沸石催化剂的表征,结果表明,金属银对电子的捕获使得电子-空穴对有效分离， 从而使银 改性光催化剂的活性提高.     

水热合成条件对Bi_2WO_6可见光催化性能的影响

TiO2被广泛应用于光催化领域,但其只能在紫外光下响应,对太阳光利用率极低,因此开发能够吸收可见光的催化剂很有必要。以Bi(NO3)3.5H2O和Na2WO4.2H2O为原料,采用温和的水热法在不同温度、pH条件下制备了可见光响应的光催化剂Bi2WO6。通过XRD、DRS等技术对合成Bi2WO6进行表征。以氙灯为光源(λ>420nm),以罗丹明B(RhB)为模型污染物进行降解实验,探讨不同条件下合成的Bi2WO6的可见光光催化性能。实验结果表明,在140℃、pH=1条件下合成的Bi2WO6对RhB的降解效果最好,反应4h,脱色率达到97.7%。