单斜与锐钛矿双晶相TiO2/MWNTs复合材料的制备及其可见光光催化活性

以超强耐酸碱的表面活性剂-丁基封端脂肪醇聚氧乙烯醚作为晶型调节剂,利用钛酸丁酯和氢氧化钠的水热反应制备了单斜相与锐钛矿相双晶相TiO2/多壁碳纳米管(简称MWNTs)复合材料,并考察了复合材料的可见光光催化活性。结果显示:MWNTs的加入可调控TiO2的晶相组成,增强TiO2的光催化活性,其中含5%MWNTs的样品具有较高的催化降解效率;随煅烧温度的升高,样品的光催化活性大幅提升。其机理归因于(1)促进单斜相和锐钛矿相双晶相结构的形成;(2)碳纳米管优良的导电作用及碳纳米管/TiO2间的异质结效应;(3)高温下碳纳米管分解产生的碳元素掺杂作用。     

等离子体修饰磁载TiO2光催化剂性能研究

以化学共沉法制备的CoFe₂O₄纳米粒子为磁核,采用TiCl₄水解包覆技术制备磁载二氧化钛纳米复合粒子CoFe₂O₄ /TiO_x(TCF),利用低温等离子体技术修饰TCF制备了CoFe₂O₄/TiO₂(PTCF)纳米复合光催化剂。运用VSM(振动样品磁强计)技术对样品磁性能进行研究,结果表明：等离子体修饰后的复合材料仍具有较高的饱和磁化强度,可在外加磁场作用下实现催化剂在水中的分离与回收;样品的XRD、TEM和UV-Vis分析测试结果表明：等离子体修饰后的复合材料有锐钛矿型TiO₂存在;TEM谱图显示磁核CoFe₂O₄的平均粒径约为20 nm,TCF复合粒子的粒径约为30~40 nm,TiO₂包覆层的厚度为10~20 nm。与纯TiO₂相比PTCF样品对光的吸收拓展到整个紫外-可见区,扩大了光谱响应范围;对甲基橙溶液降解的光催化活性评价研究表明：TCF复合粒子等离子体修饰后的PTCF纳米复合光催剂的光催化活性明显提高。     

阳极氧化法制备TiO2纳米管及其光催化性能

纳米TiO₂对诸多环境污染物有显著的光催化降解作用,光催化已发展成为新型环境污染治理技术。本文采用阳极氧化法制备出TiO₂纳米管,对比了四种电解液组成(A氟化铵+硫酸铵+水;B氟化铵+硫酸铵+乙酸+水;C氟化铵+硫酸铵+甘油+水;D氢氟酸+二甲基亚砜(DMOS)+乙醇)对催化剂表面形貌及光催化性能的影响。结果表明,电解液A和C都制备出了形貌清晰的TiO₂纳米管,管径约为60~74 nm。样品经400 ℃煅烧,TiO₂晶型主要为锐钛矿相;经500 ℃煅烧,出现少量金红石相;经700 ℃煅烧,晶型全部为金红石相。具有良好形貌的TiO₂纳米管同时具有良好的紫外光吸收能力。当亚甲基蓝初始浓度为10 mg·L^-1,经500 ℃煅烧的TiO₂纳米管光催化活性最佳,光照30 min亚甲基蓝的降解率达89.98%。亚甲基蓝光催化降解反应符合一级反应动力学,反应速率常数为0.079 30。     

火焰辅助热解方法制备Ag2O/TiO2及其光催化制氢性能

以钛酸丁酯和硝酸银为前驱体,采用一步火焰辅助热解法制备了Ag₂O/TiO₂光催化剂并研究了样品在紫外-可见光照射下的光催化制氢性能。利用X射线衍射（XRD）、扫描电子显微镜（SEM）、透射电子显微镜（TEM）、X射线光电子能谱（XPS）和紫外-可见漫反射吸收光谱（UV-Vis DRS）对样品进行了表征。XRD结果表明TiO₂均为锐钛矿晶型,Ag的引入对XRD结果无明显影响。SEM图显示未修饰的TiO₂是微球形貌,随着引入Ag含量的增加,微球减少直至消失。通过XPS分析和化学沉淀法表明样品中Ag的存在形式为Ag₂O。UV-Vis DRS测试发现引入Ag后提高了样品的光吸收。前驱体中Ag的量影响样品的光催化活性,最高的光催化制氢的活性可以达到相同条件下的P25的15倍。对光催化反应后的样品进行分析,认为在光催化过程中部分Ag₂O通过光生电子转化为Ag形成Ag/TiO₂,进一步提高光催化制氢活性。     

TiO2/Gd2O3纳米粉体的制备、表征及光催化活性

利用酸催化的溶胶-凝胶法制备了纯TiO₂和Gd³⁺(0.5wt%)掺杂的TiO₂纳米粉体，采用XRD、BET、XPS、紫外-可见漫反射谱(DRS)和表面光电压谱(SPS)等技术进行了表征；以亚甲基蓝(MB)的光催化降解为探针反应，评价了其光催化活性；探讨了Gd³⁺掺杂对TiO₂纳米粉体的光催化活性的影响机制。结果表明，TiO₂/Gd₂O₃纳米粒子对MB溶液的光催化活性提高到纯TiO₂的1.5倍。掺杂Gd³⁺可以强烈抑制TiO₂由锐钛矿相向金红石相的转变；阻碍TiO₂晶粒的生长；提高高温组织稳定性，改善粉体的表面织构特性；形成光生电子的浅势捕获陷阱，抑制e^-/h⁺复合，这些因素共同作用最终导致TiO₂/Gd₂O₃纳米粉体的光催化活性明显提高。XPS分析结果证实，掺杂Gd³⁺导致粉体的表面羟基含量降低。由于产生了量子尺寸效应，复合粉体的紫外吸收带边蓝移，光的吸收能力略有降低。     

原位红外光谱法研究La/TiO2对有机污染物的光催化降解

本工作采用改进的溶胶-凝胶法和浸渍法制备了TiO₂掺杂稀土离子La³⁺的La/TiO₂光催化剂，运用XRD、N₂吸附脱附、紫外可见漫反射光谱(DRS)、表面光电压谱(SPS)等手段进行表征，同时利用原位红外技术考察了La/TiO₂样品光催化降解乙烯、丙酮、苯的气-固相光催化氧化反应，对其光催化降解有机污染物的过程进行了研究。结果表明，TiO₂经适量La³⁺掺杂后，锐钛矿晶型的含量增加，晶粒度减小，比表面积增大，禁带宽度增加，表面光电压信号增强，光生电子-空穴对有效分离；La/TiO₂样品对乙烯、丙酮、苯的光催化性能与纯TiO₂相比均有不同程度的改善，乙烯可以被光催化氧化完全矿化生成CO₂，而丙酮被光催化氧化可能生成中间产物丙酸，苯被光催化氧化可能生成中间产物苯酚和苯醌。     

TiO2纳米薄片的合成及其光催化降解苯酚性能

以钛酸纳米管为前驱体,通过添加NaF高温水热合成了(001)面暴露的TiO₂纳米薄片,并对其催化苯酚光降解行为进行了研究。结果表明经水热反应后,钛酸型TiO₂纳米管(NT)转晶成锐钛矿型TiO₂纳米薄片(NS),且具有高(001)暴露面。和NT相比,NS对苯酚的光催化降解活性显著提高,其活性随水热温度升高而增加。NS光催化去除苯酚符合一级动力学,其中200 ℃合成的NS反应速率常数k最高,为0.083 min^-1。同时,苯酚的光催化反应初活性与其初浓度的关系符合Langmuir-Hinshelwood模型,表明苯酚的光催化降解受吸附控制。     

TiO2形态结构与光催化活性关系的研究

本文介绍了TiO₂多相光催化剂的作用机理及其结构特性对光催化活性的影响,并对TiO₂的晶相组成、晶粒尺寸、比表面积、表面形态与光催化活性的关系作了综述。     

添加NaBF4对阳极氧化法制备TiO2纳米管光催化剂的影响

在阳极氧化电解液中添加NaBF₄制得了具可见光活性的B掺杂TiO₂纳米管阵列（B/TNTs）。采用扫描电镜（FE-SEM）、能谱仪（EDS）、X射线衍射（XRD）、傅立叶红外光谱（FTIR）、紫外-可见漫反射光谱（UV-Vis DRS）以及X射线光电子能谱（XPS）对样品进行表征,以亚甲基蓝（MB）的光催化降解为目标反应评价其光催化活性。结果表明：添加NaBF₄后,TiO₂纳米管表面形貌变化较大;B掺入到TiO₂晶格中形成B-O-Ti键;B掺杂使得TiO₂纳米管表面羟基量增加、光学带隙能减小、光吸收阀值红移,且B掺杂量越多,其相应值的变化量越大;B掺杂能促进TiO₂锐钛矿相的发育,纳米管经550℃煅烧后仍保持未掺杂样品的锐钛矿相结构;NaBF₄的最佳添加量为0.6%（w/w）时,所得样品光催化活性最佳,可见光下光催化降解MB的4 h降解率由未添加的39.90%提高至75.15%,且反复使用10次后其光催化性能基本保持不变;总有机碳（TOC）分析结果表明,MB在可见光下能被B/TiO₂有效矿化。     

SO42-改性后的TiO2(锐钛和/或金红石)表面上MoO3的分散性质研究

采用红外(IR)、拉曼(Raman)、X-射线衍射(XRD)、程序升温还原(TPR)等方法考察了经硫酸根改性后的金红石(SR)与锐钛矿(SA)的混合比例变化时的负载型催化剂，MoO₃ / TiO₂(SR+SA)，的一些物理化学性质(如活性组分MoO₃的分散行为、表面酸碱性、氧化还原性)的变化规律。结果表明：对于MoO₃ / TiO₂(SR+SA)样品，低含量MoO₃表面分散时倾向于优先与混合载体中的改性金红石(SR)发生作用；TiO₂载体表面SO₄^2-的存在，使得载体表面产生了新的酸性位，导致样品中表面分散的钼物种主要以聚合八面体状态存在。     

Carbon-doped anatase TiO2 nanotube array/glass and its enhanced photocatalytic activity under solar light

To enhance the photocatalytic activity under solar light, highly ordered TiO₂ nanotube arrays (TNAs) film with anatase phase was fabricated on glass and successfully doped with carbon at various temperatures of 450–550 °C. The characterization results indicate that, after carbon doping, the TNAs still remained nanotubular structure with anatase phase. But their optical response shifted from UV to the visible light region and the recombination of photogenerated carriers was suppressed effectively. It is more important that the carbon-doped TNAs/glass (C-TNAs) samples exhibited high solar light photocatalytic activity, and 68%, 61% and 56% MO was photodegraded in 150 min by the C-TNAs calcined at 550, 500 and 450 °C, respectively. Especially, the apparent reaction rate constant of C-TNAs calcined at 550 (k, 0.065 min⁻¹) with the highest activity is 3.6 times that of pristine anatase TNAs (k, 0.018 min⁻¹). It is clear that carbon doping enhanced the photocatalytic activity under sunlight at optimized annealing temperature. The efficient activity could be attributed to the synergetic effects of strong visible light absorption, good crystallization, large surface, and enhanced separation of photoinduced carriers.     

Preparation and Characterization of Bismuth Doped TiO2 Thin Films

A series of Bismuth-doped titanium oxide (Bi-doped TiO₂) thin films on glass substrates have been prepared by sol-gel dip coating process. The prepared catalysts were characterized by XRD and XPS. The photocatlytic activity of the thin film catalysts was evaluated through the photodegradation of aqueous methyl orange under UV illumination. The experiments demonstrated that the Bi-doped TiO₂ prepared was anatase phase. The doped bismuth was in the 3⁺ oxidation state. The presence of Bi significantly enhanced the photocatalytic activity of TiO₂ films. At calcination temperature of 500°C, with doping concentration of 2 wt %, Bi-doped TiO₂ thin film showed the highest photocatalyic activity.     

Photocatalytic activities of C–N-doped TiO2 nanotube array/carbon nanorod composite

A C–N-doped TiO₂ nanotube (NT)/carbon nanorod composite is fabricated by chemical vapor deposition (CVD). Carbon nanorods are grown from the TiO₂ NTs, and partly graphitized, while TiO₂ is in the mixture of anatase and rutile. The C–N doping shifts the absorption edge of TiO₂ NTs to the visible light region; the formed carbon nanorods promote the charge carrier transfer from the TiO₂ surface to the electrolyte. Under the simulated solar light irradiation, the C–N-doped TiO₂ NTs show higher photocatalytic activity in the degradation of methyl orange (MO) than the undoped TiO₂ NTs.     

超临界流体干燥法制备纳米TiO2-SnO2-SiO2复合光催化剂及其光催化性能研究

半导体多相光催化法作为一种污染治理新技术越来越受到人们的重视,在所使用的半导体光催化剂中,TiO2以无毒,催化活性高,价廉,无污染等特点,成为最具有前途的绿色环保型催化剂之一[1],但其自身具有局限性,如禁带宽度大,需在近紫外光下才能激发产生电子空穴对,对太阳光的利用率仅     

Characterization and activity of visible-light-driven TiO2 photocatalyst codoped with nitrogen and cerium

Nitrogen and cerium codoped TiO₂ photocatalysts were prepared by a modified sol-gel process with doping precursors of cerium nitrate and urea, and characterized by X-ray diffraction (XRD), thermogravimetry-differential scanning calorimetry (TG-DSC), X-ray photoelectron spectra (XPS) and ultraviolet-visible light diffuse reflectance spectra (UV-vis DRS). Results indicate that anatase TiO₂ is the dominant crystalline type in as-prepared samples, and CeO₂ crystallites appear as the doping ratio of Ce/Ti reaches to 3.0 at%. The TiO₂ starts to transform from amorphous phase to anatase at 987.1 K during calcination, according to the TG-DSC curves. The XPS show that three major metal ions of Ce³⁺, Ce⁴⁺, Ti⁴⁺ and one minor metal ion of Ti³⁺ coexist on the surface. The codoped TiO₂ exhibits significant absorption within the range of 400-500 nm compared to the non-doped and only nitrogen-doped TiO₂. The enhanced photocatalytic activity of the codoped TiO₂ is demonstrated through degradation of methyl orange under visible light irradiation.     

原位红外光谱法研究Gd3+掺杂TiO2光催化降解乙烯性能

随着环境污染的日益严重,寻求环境友好、节能、高效的污染治理技术已成为各国科学研究者致力的目标。以TiO2半导体为主的多相光催化氧化技术因与传统污染处理技术相比具有许多优点而倍受青睐,但是,目前以TiO2为基础的光催化技术还存在量子效率低、太阳能利用率低等技术难题[1,2     

Synthesis and photocatalytic activity for water-splitting reaction of nanocrystalline mesoporous titania prepared by hydrothermal method

Nanocrystalline mesoporous TiO₂ was synthesized by hydrothermal method using titanium butoxide as starting material. XRD, SEM, and TEM analyses revealed that the synthesized TiO₂ had anatase structure with crystalline size of about 8 nm. Moreover, the synthesized titania possessed a narrow pore size distribution with average pore diameter and high specific surface area of 215 m²/g. The photocatalytic activity of synthesized TiO₂ was evaluated with photocatalytic H₂ production from water-splitting reaction. The photocatalytic activity of synthesized TiO₂ treated with appropriate calcination temperature was considerably higher than that of commercial TiO₂ (Ishihara ST-01). The utilization of mesoporous TiO₂ photocatalyst with high crystallinity of anatase phase promoted great H₂ production. Furthermore, the reaction temperature significantly influences the water-splitting reaction.     

Synthesis of nanosized TiO2/SiO2 particles using microwave processes and their photocatalytic activity on the decomposition of orange II

The nanosized titania and TiO₂/SiO₂ particles were prepared by the microwave-hydrothermal method. The effect of physical properties TTIP/TEOS ratio and calcination temperature has been investigated. The major phase of the pure TiO₂ particle is of the anatase structure, and a rutile peak was observed above 800°C. In TiO₂/SiO₂ particles, however, no significant rutile phase was observed, although the calcination temperature was 900°C. No peaks for the silica crystal phase were observed at either silica/titania ratio. The crystallite size of TiO₂/SiO₂ particles decreases as compared to pure TiO₂ at high calcination temperatures. The TiO₂/SiO₂ particles show higher activity on the photocatalytic decomposition of orange II as compared to pure TiO₂ particles.     

单斜与锐钛矿双晶相TiO2的水热法制备与机理探讨

以一种具有超强耐酸碱的表面活性剂-丁基封端脂肪醇聚氧乙烯醚作为晶型调节剂,利用钛酸丁酯和氢氧化钠的水热反应制备了双晶相(单斜相与锐钛矿相)TiO2,考察了丁基封端脂肪醇聚氧乙烯醚和钛酸丁酯的物质的量比R、反应时间、反应温度等因素对产物的晶相组成的影响,并对不同条件下的晶相转变机理进行了初步探讨。