镶嵌Pt的二氧化钛纳米管的合成及其光催化性能研究

以金红石相二氧化钛(TiO₂)粉体为原料,采用水热法合成了二氧化钛纳米管(Titania nanotubes,简写为TNTs),然后把H₂PtCl₆的无水乙醇溶液引入到TNTs中,得到镶嵌Pt的二氧化钛纳米管(Pt/TNTs)。利用透射电镜(TEM)、X射线衍射(XRD)和紫外-可见光谱(UV-Vis)对产物进行了表征,并重点研究了Pt/TNTs的光催化性能。结果表明,有直径约为3 nm的 Pt纳米粒子插入到了TNTs中,且Pt粒子以Pt单质的形式存在。Pt/TNTs在可见光区域表现出较强的吸收,并且其起始吸收带边发生明显红移。紫外光催化降解甲基橙实验结果表明,金红石相TiO₂,TNTs和Pt/TNTs对甲基橙溶液的降解率分别达到46.8%, 57.2%和84.6%,Pt/TNTs的光催化活性较金红石相二氧化钛粉体和纯TNTs有显著的提高。     

锐钛矿相TiO2光学性质的计算

TiO₂具有良好的光学、电学和化学性质,锐钛矿相 TiO₂具有更突出的光催化特性,是一种有广泛用途的宽禁带氧化物半导体。利用基于密度泛函理论的第一原理全电势线性缀加平面波方法计算锐钛矿相TiO₂介电函数的实部、虚部和光学吸收系数,其中能隙值利用剪刀算符修正为3.2 eV。计算结果与实验符合得很好,同时说明广义梯度近似与局域密度近似相比对锐钛矿相TiO₂光学性质的计算没有明显的改善。     

大气可吸入颗粒物中锐钛矿的发现及意义

激光拉曼微探针(laser Raman microprobe,简称LRM)能将激光聚焦在1 μm2的极小区域进行分子成分和结构的微区分析,是一种可靠的物相鉴定手段,非常适用于单个微小颗粒物的物相鉴定。文章利用LRM对北京市大气可吸入颗粒物(PM₁₀)进行单颗粒物相分析 将实验图谱与Renishaw矿物与无机材料拉曼光谱数据库中标准图谱进行对比,通过简正坐标分析对谱带进行指认和对各谱峰分子类型及振动模进行归属,首次在PM₁₀中发现了锐钛矿型TiO₂,其实验图谱具有638 cm-1处的较强峰以及398和517 cm-1处中等强度峰,为O—Ti—O特征振动,确认了大气中富Ti颗粒的矿物物相为锐钛矿型TiO₂。锐钛矿型TiO₂是一种重要的光催化剂,锐钛矿与其他矿物颗粒(尤其是含Ca碳酸盐)的聚集能够加剧非均相反应的发生。锐钛矿的晶体结构及所处大气环境的相对湿度和pH值对其光催化反应有重要影响。     

I掺杂金红石TiO$lt;sub$gt;2$lt;/sub$gt;(110)面的第一性原理研究

利用基于密度泛函理论的第一性原理研究了I掺杂金红石TiO₂（110）表面的形成能和电子结构,分析了不同掺杂位置的结构对TiO₂光催化性能的影响. 计算表明,氧化环境下I最容易替代掺杂表面五配位的Ti,而还原环境下最容易替代掺杂表面的桥位氧. I替位Ti或I替位O都能降低禁带宽度,可能使TiO₂吸收带出现红移现象或产生在可见光区的吸收,其中I替位桥位氧的禁带宽度最小. 吸收光谱表明,I掺杂不仅能提高TiO₂可见光响应,同时可增加紫外光的吸收能量,提高其可见光及紫外光下的光催化性能. 关键词： 第一性原理 I掺杂 2(110)')" href="#">金红石相TiO₂(110) 光催化     

Ce掺杂Bi2O3 光催化剂的制备、表征及其可见光催化性能

采用水热-焙烧法制备了Ce掺杂的可见光响应的Bi₂O₃光催化剂（Ce-Bi₂O₃）。利用 XRD、FT-IR、XPS和 UV-Vis对不同Ce-Bi₂O₃样品进行了表征分析,并以光催化降解金橙Ⅱ溶液为探针反应,考察了Ce-Bi₂O₃的可见光催化性能。结果表明,Ce掺杂可以减小催化剂的禁带宽度,使光谱响应范围向可见光拓展。掺杂的Ce可取代Bi₂O₃晶格中部分Bi,形成Bi-O-Ce键,并生成了少量铈铋复合氧化物（Bi_7.38Ce_0.62O_12.31）,它们的存在有效地抑制了光生电子-空穴对的复合,有助于提高Bi₂O₃的可见光催化活性。但焙烧时间过长将导致Ce-Bi₂O₃催化剂的表面发生烧结现象,致使其催化活性降低。可见光照射下的金橙Ⅱ光催化降解实验表明,经2 h焙烧后得到的Ce/Bi的量比为0.5 的Ce-Bi₂O₃催化剂具有最佳的光催化活性。     

Pr掺杂TiO2光催化剂的制备及其对酸性品红降解反应的催化性能

以钛酸四丁酯为前躯物,采用溶胶-凝胶法制备了掺杂不同含量Pr的TiO2光催化剂,利用XRD,TG-DTA,AFM,UV-Vis,FTIR等手段对催化剂进行了表征。并通过酸性品红光催化降解实验对其光催化性能进行了评价,考查了实验条件,如催化剂用量,烧结温度,掺杂量等对催化剂催化活性的影响。Pr2O3的掺杂阻碍了TiO2晶相由锐钛矿型向金红石型的转变,使TiO2的粒径减小,比表面积增大,催化活性增强。当Pr掺杂量为0.8%,催化剂用量为0.03g,烧结温度为500℃时,酸性品红的降解率达到97%以上,酸性品红的降解反应为准一级反应。     

钛氧化物结构及其拉曼光谱表征

采用密度泛函理论(DFT),对几种钛的氧化物晶体结构进行了几何构型优化,得到了与X-ray晶体衍射实验结果相一致的结构参数。在优化几何构型基础上进行了分子振动模的分析和计算,钛氧化物均采用数字化基组和局域密度近似,并选择vwn对局域交换相关能量参数化,使用自旋非限制函数。同时,测定了钛的氧化物(TiO, Ti₂O₃,Ti₃O₅,锐钛矿型TiO₂和金红石型TiO₂)几种晶体的拉曼光谱,并分别解释了相关的拉曼活性振动模。结果表明：计算的频率与实验结果比较一致,理论计算频率可以指导实验谱图谱峰位置的归属分析。通过钛的一系列氧化物的常温拉曼光谱分析, 得知不同氧化物有不同特征峰,有利于含钛氧化物材料类型的诊断,为沟通结构和性能的相互关系奠定基础。     

C自掺杂TiO2纳米棒的制备与光催化性能研究

本文以TiC为前驱体和掺杂源,采用一步水热法合成了具有可见光吸收的C自掺杂金红石相TiO2纳米棒．样品的结构、形貌、化学态和光学性质等可通过X射线衍射仪（XRD）、扫描电子显微镜（SEM）、傅里叶变换红外光谱仪（FT-IR）、X射线光电子能谱仪（XPS）以及紫外可见分光光度计（UV-vis）来表征．所合成的样品具有较强的光催化活性,可通过在可见光照射下降解有机染料罗丹明B（RhB）来验证．C自掺杂TiO2所呈现的较强光催化活性是由于其具有小的能带间隙（2.74 eV）、大的比表面积和高的电子-空穴对分离率．     

C自掺杂TiO2纳米棒的制备与光催化性能研究

本文以TiC为前驱体和掺杂源,采用一步水热法合成了具有可见光吸收的C自掺杂金红石相TiO2纳米棒．样品的结构、形貌、化学态和光学性质等可通过X射线衍射仪（XRD）、扫描电子显微镜（SEM）、傅里叶变换红外光谱仪（FT-IR）、X射线光电子能谱仪（XPS）以及紫外可见分光光度计（UV-vis）来表征．所合成的样品具有较强的光催化活性,可通过在可见光照射下降解有机染料罗丹明B（RhB）来验证．C自掺杂TiO2所呈现的较强光催化活性是由于其具有小的能带间隙（2.74 eV）、大的比表面积和高的电子-空穴对分离率．     

锐钛矿相和金红石相TiO2:Nb的光电性能研究

采用基于密度泛函理论的第一性原理计算了锐钛矿相和金红石相TiO₂:Nb的晶体结构、电子结构和光学性质. 结果表明, 在相等的摩尔掺杂浓度下(6.25%), 锐钛矿相TiO₂:Nb的导带底电子有效质量小于金红石相TiO₂:Nb, 且前者室温载流子浓度是后者的两倍左右, 即具有更大的施主杂质电离率, 从而解释了锐钛矿相TiO₂:Nb比金红石相TiO₂:Nb具有更优异电学性能的实验现象. 光学计算也表明锐钛矿相在可见光区有更大的透过率, 从而在理论上解释了锐钛矿相TiO₂:Nb比金红石相TiO₂:Nb更适于做透明导电材料的原因. 计算结果与实验数据能较好符合. 关键词： 2:Nb')" href="#">TiO₂:Nb 第一性原理 电子结构 光学性能     

Ti~+离子注入结合热退火法制备TiO_2纳米薄膜研究

利用金属蒸发真空多弧离子源(MEVVA源)注入机将Ti+离子注入到高纯石英玻璃衬底中,离子注入的加速电压为20 k V,注入剂量为1.5×1017和3×1017ions/cm2,将注入样品在氧气气氛下进行热退火处理,制备了TiO2纳米薄膜。采用光吸收谱、拉曼光谱、X射线光电子能谱、扫描电子显微镜和透射电子显微镜对注入样品进行了测试和表征,分析了TiO2薄膜的形成机理。在热退火过程中衬底中离子注入的Ti原子向外扩散到衬底表面被氧化形成了TiO2。TiO2的形成、晶粒尺寸和晶体结构依赖于热退火温度,而形成TiO2薄膜的厚度主要受离子注入剂量和热退火时间的影响。实验结果表明,该方法制备的TiO2纳米薄膜将有望应用于制备具有光催化、自清洁等特殊性能的自清洁玻璃。     

Hydrothermal synthesis of well-dispersed ultrafine N-doped TiO2 nanoparticles with enhanced photocatalytic activity under visible light

Ultrafine nitrogen-doped TiO₂ nanoparticles with narrow particle size distribution, good dispersion, and high surface area were synthesized in the presence of urea and PEG-4000 via a hydrothermal procedure. TEM observation, N₂ adsorption, XRD, UV-vis spectroscopy, the Raman spectroscopy and XPS analysis were conducted to characterize the synthesized TiO₂ particles. The synthesized TiO₂ particles were a mixture of 49.5% anatase and 50.5% rutile with a size of around 5 nm. The photocatalytic activities were tested in the degradation of an aqueous solution of a reactive Brilliant Blue KN-R under both UV and visible light. The synthesized TiO₂ particles showed much higher photocatalytic activity than a commercial P25 TiO₂ powder under both UV and visible light irradiations. The high performance is associated to N doping, the reduced particle size, good dispersion, high surface area, and a quantum size effect.     

Curcumin-sensitized TiO2 for enhanced photodegradation of dyes under visible light

Curcumin was coated on P25 TiO₂ by using impregnation method from freshly prepared curcumin solution. The resulting products (Cur–TiO₂–P25) was studied by several techniques such as X-ray diffraction, scanning electron microscopy, transmission electron microscopy, Fourier-transformed infrared spectroscopy, specific surface area by the Brunauer–Emmett–Teller method, and UV–Vis diffused reflectance spectroscopy. Experimental results revealed that impregnation of curcumin at 0.5, 3, 5, and 7 wt% did not affect the native phase of anatase and rutile in P25 significantly, however, it caused red shift of absorption onset in all curcumin-coated samples. The Cur–TiO₂–P25 showed enhanced adsorption efficiency and increased photocatalytic activity under visible light with optimal result at 5 wt% curcumin content. Commercial anatase and rutile coated with curcumin (Cur–TiO₂–an and Cur–TiO₂–ru) were also prepared by the same method for the use in comparative studies of photodegradation of dyes. Cur–TiO₂–an and Cur–TiO₂–ru were also characterized with some selected equipment above but not as extensively as the Cur–TiO₂–P25. Curcumin coating helped improve photocatalytic efficiencies of P25 and anatase but not for rutile. The mechanism of photocatalytic reaction was proposed that under visible light irradiation, curcumin molecule could act as dye sensitizing agent that injected electron into the conduction band of TiO₂ leading to photodegradation of dyes.     

Enhanced photocatalytic performance of TiO2 particles via effect of anatase–rutile ratio

In the present work anatase–rutile transformation temperature and its effect on physical/chemical properties as well as photocatalytic activity of TiO₂ particles were investigated. The characterisation of the synthesised and annealed TiO₂ particles were determined by X-Ray Powder Diffraction (XRD), scanning electron microscope (SEM), dynamic light scattering (DLS) and Brunauer–Emmett–Teller surface area analysis (BET). The refraction in the ultraviolet–visible (UV–vis) range was assessed using a dual-beam spectrophotometer. The photocatalytic performance of the particles was tested on methylene blue solution. The XRD data indicated that the percentage of rutile increased with the annealing temperature and almost 100% of anatase transformed to rutile at 1000 °C. In addition, the phase transformation was a linear function of annealing temperature so phase composition of TiO₂ can be controlled by changing the annealing temperature. The SEM and BET results presented the increase of agglomerate size and the decrease of specific surface area with the increasing annealing temperature. This proved that anatase has smaller particle size and higher surface area than rutile. The photocatalytic activity of the annealed TiO₂ powders reduced with the increase of annealing temperature. The samples annealed at 900 °C and 925 °C with anatase: rutile ratio of 92:8 and 77:23, respectively, showed the best activity. These results suggested that the photocatalytic activity of TiO₂ particles is a function of phase composition. Thus it can be enhanced by changing its phase composition which can be controlled by annealing temperature.     

快重离子辐照金红石型TiO2的肿胀效应及化学蚀刻行为研究

二氧化钛（Titatium Dioxide,简称TiO₂）晶体在中能重离子辐照时表面会出现肿胀效应, 肿胀高度与入射离子的电子能损和辐照注量有关。 辐照后的TiO₂在一定条件下能够被氢氟酸溶液化学蚀刻,化学蚀刻的电子能损阈值为8.2keV/nm,未辐照TiO₂呈现几乎零蚀刻率。要达到饱和蚀刻深度,辐照离子的注量必须大于或等于1×1013ions/cm2。采用离子辐照的潜径迹理论分析研究了辐照损伤及对化学蚀刻的影响, 快重离子辐照结合化学蚀刻是制备TiO₂微结构的有效方法。 There appears volume swelling on the surface of the irradiated rutile TiO₂ crystal and the volume swelling is affected by the ion fluence and the electronic stopping power. To induce adequate irradiation damage for the chemical etching, the irradiation parameters must fulfill some requirement. There is minimum electronic stopping power for the chemical etching of the irradiated region in TiO₂ crystal, which is about 8. 2 keV/nm. If the ion fluence is below 1×1013ions/cm2, the saturated etching depth of the irradiated region in TiO₂crystal cannot be reached. The irradiation damage based on latent track formation frame and the theoretical linkage to the etching technique is investigated. It is hopeful to fabricate micro and nano scale structurce in rutile TiO₂ crystal by using the ion irradiation and chemical etching technique.      

改性高岭土的制备、表征及其光催化性能

通过焙烧和H₂SO₄浸渍制备了改性高岭土。利用热重-差热(TG-DTA)、扫描电镜(SEM)结合能谱(EDS)、X射线衍射(XRD)、紫外-可见光吸收光谱(UV-Vis)及BET比表面积测定等手段对所获得样品进行了表征。以甲基橙为模型反应物,评价了样品的光催化活性。同未经酸改性的焙烧高岭土相比,改性高岭土的UV-Vis光谱吸收边带产生明显红移。样品具有更高的光吸收效率,促进了其光催化活性。吡啶吸附红外光谱(Py-IR)分析显示,改性高岭土表面具有酸性。当酸浸过程的H₂SO₄溶液浓度高于30%时,得到的样品同时具有Brnsted和Lewis酸位。光谱分析结果结合光催化评价结果表明,样品的酸性是影响其光催化性能的主要因素。     

Ti<Superscript>3+</Superscript>-doped TiO<Subscript>2</Subscript> hollow sphere with mixed phases of anatase and rutile prepared by dual-frequency atmospheric pressure plasma jet

A novel method of synthesizing Ti³⁺-doped TiO₂ was proposed. Ti³⁺-doped TiO₂ hollow spheres were prepared with different thickness of carbon shell by using atmospheric pressure plasma jet generated by dual-frequency power sources. The as-synthesized Ti³⁺-doped TiO₂ hollow microspheres were characterized by X-ray diffraction (XRD) pattern, scanning electron microscope (SEM) images, high-resolution transmission electron microscopy (HRTEM) images, Raman spectra, X-ray photoelectron spectroscopy (XPS), and UV–vis spectra. These results indicated that these samples had mixed phases of anatase and rutile and the structure of hollow sphere varied with different thickness of carbon shell. The Ti-O-C chemical bond was the connection between the TiO₂ hollow sphere and carbon layer. Amount of Ti³⁺ ions were found, which were accompanied with the formation of oxygen vacancies. Meantime, the as-synthesized catalysts also display strong absorption in the visible light region and have a narrow band energy gap. Optical emission spectroscopy (OES) was used to observe different excited species in the discharge area. These results showed that the oxygen content had a significant impact on the number of oxygen vacancies. Finally, the photocatalytic activities of as-prepared samples were evaluated by decomposition of rhodamine B aqueous solution, which showed better photocatalytic activity under UV–vis light irradiation.     

Comparison of catalytic activities for photocatalytic and sonocatalytic degradation of methylene blue in present of anatase TiO2-CNT catalysts

Anatase TiO(2)-CNT catalysts with high specific surface areas were prepared by depositing TiO(2) particles on the surface of carbon nanotubes (CNTs) using a modified sol-gel technique. These catalysts prepared with different amounts of CNTs were characterized by nitrogen adsorption, Fourier Transform infrared (FT-IR) spectroscopy, scanning electron microscope (SEM), Transmission Electron Microscope (TEM), X-ray diffraction (XRD), Raman spectroscopy, energy dispersive X-ray (EDX) and ultraviolet-visible (UV-Vis) spectroscopy. The catalytic activity of the anatase TiO(2)-CNT catalysts was assessed by examining the degradation of methylene blue (MB) from model aqueous solutions as a probe reaction under visible light and ultrasonic irradiation. The synergistic effect of the greater surface area and catalytic activities of the composite catalysts was examined in terms of the strong adsorption ability and interphase interaction by comparing the different amounts and roles of CNTs in the catalysts.     

Enhanced visible light photocatalytic properties of Fe-doped TiO2 nanorod clusters and monodispersed nanoparticles

In order to get photocatalysts with desired morphologies and enhanced visible light responses, the Fe-doped TiO₂ nanorod clusters and monodispersed nanoparticles were prepared by modified hydrothermal and solvothermal method, respectively. The microstructures and morphologies of TiO₂ crystals can be controlled by restraining the hydrolytic reaction rates. The Fe-doped photocatalysts were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), UV-vis absorption spectroscopy (UV-vis), N₂ adsorption-desorption measurement (BET), and photoluminescence spectroscopy (PL). The refinements of the microstructures and morphologies result in the enhancement of the specific surface areas. The Fe³⁺-dopants in TiO₂ lattices not only lead to the significantly extending of the optical responses from UV to visible region but also diminish the recombination rates of the electrons and holes. The photocatalytic activities were evaluated by photocatalytic decomposition of formaldehyde in air under visible light illumination. Compared with P25 (TiO₂) and N-doped TiO₂ nanoparticles, the Fe-doped photocatalysts show high photocatalytic activities under visible light.     

Preparation and characterization of TiO2 photocatalysts co-doped with iron (III) and lanthanum for the degradation of organic pollutants

Titanium dioxide photocatalysts co-doped with iron (III) and lanthanum were prepared by a facile sol-gel method. The structure of catalysts was characterized by X-ray diffraction (XRD), Raman spectroscopy, UV-vis diffuse reflectance spectroscopy and X-ray photoelectron spectroscopy (XPS). The photocatalytic activities of the samples were evaluated by the degradation of methylene blue in aqueous solutions under visible light (λ > 420 nm) and UV light irradiation. Doping with Fe³⁺ results in a lower anatase to rutile (A-R) phase transformation temperature for TiO₂ particles, while doping with La³⁺ inhibits the A-R phase transformation, and co-doping samples indicate that Fe³⁺ partly counteracts the effect of La³⁺ on the A-R transformation property of TiO₂. Fe-TiO₂ has a long tail extending up the absorption edges to 600 nm, whereas La-TiO₂ results in a red shift of the absorption. However, Fe and La have synergistic effect in the absorption of TiO₂. Compared with Fe³⁺ and La³⁺ singly doped TiO₂, the co-doped simple exhibits excellent visible light and UV light activity and the synergistic effect of Fe³⁺ and La³⁺ is responsible for improving the photocatalytic activity.