稀土镧掺杂二氧化钛的光催化特性

二氧化钛有合适的禁带宽度,在光催化体系中有较好的稳定性,是一种较为理想的半导体光催化剂.近来,在太阳能转换和储存,二氧化碳还原,有害复杂有机物降解等方面都引起了广泛的研究兴趣.已有文献报导了不同的掺杂催化体系对其光催化性能的影响.Ｋａｋｕｔａ[1,2]等研究了二氧化钛复合氧化物体系的光催化性能.Ｃｈｏｉ[3]等系统地研究了过渡金属氧化物掺杂的二氧化钛的光催化性能和空穴电子复合之间的联系.也有研究者从掺杂体系的晶体结构和表面物化性质,如晶相(锐钛矿,金红石,无定形),比表面积,晶粒尺寸和表面羟基的角度讨论与光催化活性的关…     

Cu掺杂TiO2及其纳米管的制备、表征与光催化性能

通过溶胶-凝胶法和水热法制备了Cu掺杂TiO₂纳米粉末及其纳米管,并通过XRD、TEM、FE-SEM、EDS、UV-Vis/DRS等手段分析了样品的结构。发现以Cu掺杂TiO₂纳米粉末为水热反应原料制备的纳米管中不含Cu,对其原因进行了分析讨论并通过Zn掺杂TiO₂纳米粉末证实：以金属掺杂TiO₂纳米粉末为原料,通过水热法制备TiO₂纳米管中不含有相应金属离子,这是由于金属离子在强碱水热条件下形成金属配离子,使金属离子溶解于水中而不能形成金属掺杂TiO₂纳米管。对所得样品进行了光催化性能测试,发现：Cu掺杂TiO₂粉末的光催化产氢效率为0.75 μmol·(g·h)^-1,高于由其本身及P25通过水热法制备的TiO₂纳米管(分别为：0.42 μmol·(g·h)^-1,0.25 μmol·(g·h)^-1)的光催化产氢效率。     

铁酸锌掺杂对二氧化钛结构相变及光催化性能的影响

分别采用共沉淀法和溶胶-凝胶法制备铁酸锌和二氧化钛纳米粉体,较系统地研究了铁酸锌纳米掺杂对二氧化钛“锐钛矿→金红石”的结构相变及光催化性能的影响.结果表明,适量铁酸锌的掺杂可促进二氧化钛的结构相变,显著提高其光催化活性,在最佳掺杂浓度时,其光催化降解苯酚的效率可以提高2～3倍.     

水热法制备铂掺杂二氧化钛及其可见光催化性能

以纳米管钛酸为前驱体,采用水热法制备了Pt掺杂TiO2样品.水热反应过程中,纳米管钛酸表面羟基与氯铂酸发生酸碱中和反应,导致反应后pH值升高;在130°C开始纳米管钛酸晶体结构由正交晶系转变为锐钛矿相TiO2.表面化学组成分析表明,掺杂的Pt主要以+2价形式存在.以丙烯为模型污染物,评价样品的可见光(λ≥420nm)光催化活性.结果表明,Pt-TiO2具有明显的可见光光催化降解丙烯的活性,其中160°C水热处理制得的Pt-TiO2活性最高.最后讨论了低温水热法Pt掺杂的形成机理及Pt-TiO2具有可见光响应的原因.     

铂非均匀掺杂二氧化钛薄膜的光催化性能

采用溶胶-凝胶法制备了铂非均匀掺杂的二氧化钛薄膜, 并用UV-vis分光光度计及电化学工作站表征了薄膜的光吸收性能和光电化学行为, 通过对甲基橙的光催化降解动力学来表征催化剂的光催化活性. 结果表明 Pt非均匀掺杂可以明显增强二氧化钛的光催化活性, 而均匀掺杂的效果较差; Pt非均匀掺杂的最佳量为0.3 mol%. 催化剂薄膜的电化学行为显示: Pt非均匀掺杂二氧化钛薄膜的开路电压高, 交流阻抗小. 并从半导体的PN结原理探讨了Pt非均匀掺杂二氧化钛的催化活性机理.     

微波加热制备泡沫镍负载La3+掺杂纳米TiO2及其光催化降解甲醛的性能

 采用常规加热和微波加热方法制备了两种泡沫镍负载La3+掺杂的纳米TiO2光催化剂,以甲醛光催化降解为模型反应,考察了制备方法和掺杂La3+对催化剂催化性能的影响,并采用扫描电镜、透射电镜、 X射线衍射和能量分散式光谱分析对催化剂进行了表征. 结果表明,微波加热法制备的纳米TiO2具有典型的锐钛矿型晶体结构,其粒径均匀且明显小于常规加热法制备的催化剂. 泡沫镍负载1.5%La3+掺杂的TiO2的光催化性能得到明显改善,反应90 min后甲醛的降解率仍达到93%. 在实验中发现催化剂有失活现象,但经简单清洗后其活性能够恢复.     

硫掺杂钛酸(盐)纳米管的表征与可见光光催化活性

以二硫化钛为钛源和硫源,通过与NaOH水热反应成功制备了硫掺杂钛酸(盐)纳米管。 采用X射线衍射、高分辨透射电子显微镜、扫描电子显微镜、扩展X射线吸收精细结构(EXAFS)和X光微区分析等手段对所制备的硫掺杂钛酸(盐)纳米管的结构、形貌、硫掺杂状态和掺杂量进行了表征,并以可见光光催化氧化乙醇反应为探针,采用原位气相色谱技术研究了硫掺杂钛酸纳米管的可见光光催化活性;结果表明,S原子以S2-形式取代了钛酸纳米管骨架中O原子的位置, 有效实现了硫掺杂;硫掺杂钛酸(盐)纳米管壁厚平均尺寸为2.9 nm,管径平均尺寸为9.7 nm。 可见光光催化氧化乙醇反应结果表明,掺硫钛酸纳米管在极低的掺硫量条件下,表现出比未掺杂的二氧化钛纳米管具有更高的可见光光催化活性。     

N-TiO2协同单过硫酸氢钾光催化降解氧氟沙星的研究

分别以尿素、钛酸四丁酯为氮源、钛源,利用溶剂热法制备氮掺杂二氧化钛光催化剂(N-TiO2),用XRD、SEM、IR、UV-vis DRS等对改性前后的催化剂进行表征.以LED灯为光源,氧氟沙星(OFX)为模型污染物,考察了N-TiO2协同单过硫酸氢钾(PMS)光催化降解OFX的性能.研究表明,当氮、钛摩尔比为0.6,O...     

N-TiO2协同单过硫酸氢钾光催化降解氧氟沙星的研究

分别以尿素、钛酸四丁酯为氮源、钛源,利用溶剂热法制备氮掺杂二氧化钛光催化剂(N-TiO2),用XRD、SEM、IR、UV-vis DRS等对改性前后的催化剂进行表征.以LED灯为光源,氧氟沙星(OFX)为模型污染物,考察了N-TiO2协同单过硫酸氢钾(PMS)光催化降解OFX的性能.研究表明,当氮、钛摩尔比为0.6,O...     

不同前驱体制备氮掺杂二氧化钛及其光催化性能比较

在氨气气氛中和不同温度下焙烧纳米管钛酸和商业Degussa-P25,得到两系列可见光响应型氮掺杂二氧化钛光催化剂.采用高分辨透射电子显微镜、紫外-可见漫反射光谱仪和X射线衍射仪对两系列样品的形貌、光谱吸收和晶体结构等物理化学性质进行了表征和比较.通过可见光光催化氧化丙烯评价系统对两系列样品的活性进行了评价.结果表明,600℃处理纳米管钛酸得到的催化剂可见光催化活性最好,是相同条件下处理Degussa-P25得到的催化剂(N-P25)活性的3.3倍.研究表明,纳米管钛酸是制备可见光响应型光催化剂较好的前驱体.     

Photocatalytic and immobilization characteristics of immobilized ZnO and TiO2 nanopowders

Research on Chemical Intermediates - A kind of photocatalytic ZnO nanopowder and two kinds of photocatalytic TiO2 nanopowders were prepared. The ZnO nanopowder was synthesized by the solution...     

多酸修饰二氧化钛纳米管复合膜的制备、表征及其光催化降解甲基橙的研究

采用电沉积方法制备了H3PW12O40(PW12)-TiO2复合膜,通过SEM,EDX和XRD等手段,对其组成和结构进行了表征,并考察了该复合膜催化剂对降解甲基橙的催化活性.实验结果表明PW12存在于TiO2纳米管结构中,用PW12多酸修饰的TiO2纳米管比单独的TiO2纳米管展示出更好的光催化性能,由于电子能够从TiO2纳米管导带转移到多酸的LUMO能级,有效抑制了光生电子和空穴的复合,因而使PW12-TiO2复合膜表现出更高的光催化活性.     

Photocatalytic Crystalline and Amorphous TiO2 Nanotubes Prepared by Electrospinning and Atomic Layer Deposition

In this work core/shell composite polymer/TiO₂ nanofibers and from those TiO₂ nanotubes were prepared. First, poly(vinyl alcohol) (PVA) and poly(vinylpyrrolidone) (PVP) fibers were synthetized by electrospinning. They were covered with a 100 nm thick amorphous TiO₂ layer by atomic layer deposition at 50 °C. Later the polymer core was removed by two different methods: dissolution and annealing. In the case of dissolution in water, the as-prepared TiO₂ nanotubes remained amorphous, while when annealing was used to remove the polymers, the TiO₂ crystallized in anatase form. Due to this, the properties of amorphous and crystalline TiO₂ nanotubes with exactly the same structure and morphology could be compared. The samples were investigated by SEM-EDX, ATR-IR, UV-Vis, XRD and TG/DTA-MS. Finally, the photocatalytic properties of the TiO₂ nanotubes were studied by decomposing methyl-orange dye under UV light. According to the results, crystalline anatase TiO₂ nanotubes reached the photocatalytic performance of P25, while amorphous TiO₂ nanotubes had observable photocatalytic activity.     

过渡金属离子置换钛酸纳米管的制备和光催化活性

TiO2纳米粉体和纳米膜材料在光催化降解大气和水中的污染物等方面具有广泛的应用[1]。近年来,以TiO2为原料与浓N aO H反应合成的钛酸纳米管具有比其原料TiO2更大的表面积和孔体积,且对丙烯有光催化氧化降解活性而备受关注[2]。以往在对TiO2纳米粉体和纳米膜材料在光催化研究中,人们发现由于光激发产生的电子与空穴的复合,导致光量子效率很低。为克服这个缺点,人们使用过渡金属离子掺杂等多种手段对TiO2进行改性[3]。但钛酸纳米管相类似的研究还未见报道。对钛酸纳米管的结构和组成的研究表明[4],此纳米管状物的组成是N axH2-xTi3O7,…     

g-C3N4纳米管的制备及其光催化降解性能

以三聚氰胺和碳酸氢铵混合物为原料,采用简便热解法制备g-C₃N₄纳米管。热解过程中碳酸氢铵分解释放出大量的NH₃,能够诱导纳米管的形成。利用X射线衍射（XRD）、扫描电子显微镜（SEM）、红外光谱（IR）、N₂吸附-脱附、紫外-可见漫反射光谱以及紫外可见光谱（UV）等分析测试方法对该光催化剂的微观形貌结构和催化性能进行了表征。以罗丹明光催化降解为模型反应研究了g-C₃N₄纳米管的光催化活性。g-C₃N₄纳米管的表面积明显增大,且能够有效地促进光生电子转移,在可见光下具有较强的光催化性能,降解率在60和120 min时分别能达到95%和99.4%,且循环重复利用5次后降解率不低于92%。     

Effects of photoactivated titanium dioxide nanopowders and coating on planktonic and biofilm growth of Pseudomonas aeruginosa

We exploited the ability of photocatalytic titanium dioxide (TiO(2)) as an agent for the biofilm control. Two photocatalytic systems were investigated: a 3 g L(-1) suspension of TiO(2) nanopowder in demineralized water and glass slides coated with a TiO(2) thin film, achieved by sol-gel deposition. A running protocol for the photoactivation of TiO(2) was set up using the dye rhodamine B. The microorganisms studied were Pseudomonas stutzeri, Pseudomonas aeruginosa and a Bacillus cereus-group as planktonic cells. P. aeruginosa biofilms were also studied at both the solid-liquid and the solid-air interface. The TiO(2) nanopowder produced 1-log reduction of Bacillus sp. planktonic cells in 24 h, 2-log reduction of P. stutzeri planktonic cells in 30 min and 1-log reduction of P. aeruginosa planktonic cells in 2 h compared with non-photo-activated TiO(2). TiO(2) thin film produced almost a complete eradication of P. aeruginosa planktonic cells (initial concentration 10(8) cells mL(-1)) in 24 h compared to a 3-log reduction caused by UV-A light alone. In contrast, neither the photocatalytic treatment with TiO(2) film nor that with TiO(2) nanopowder had any effect on P. aeruginosa biofilms at all the interfaces investigated. Possible explanations for these findings, and for the discrepancy between this work and literature data, are discussed.     

g-C3N4纳米管的制备及其光催化降解性能

以三聚氰胺和碳酸氢铵混合物为原料,采用简便热解法制备g-C_3N_4纳米管。热解过程中碳酸氢铵分解释放出大量的NH3,能够诱导纳米管的形成。利用X射线衍射(XRD)、扫描电子显微镜(SEM)、红外光谱(IR)、N_2吸附-脱附、紫外-可见漫反射光谱以及紫外可见光谱(UV)等分析测试方法对该光催化剂的微观形貌结构和催化性能进行了表征。以罗丹明光催化降解为模型反应研究了g-C_3N_4纳米管的光催化活性。g-C_3N_4纳米管的表面积明显增大,且能够有效地促进光生电子转移,在可见光下具有较强的光催化性能,降解率在60和120 min时分别能达到95%和99.4%,且循环重复利用5次后降解率不低于92%。     

多壁碳纳米管负载TiO_2复合器件可见光光催化降解RhB

采用溶胶-凝胶法制备了多壁碳纳米管(MWCNTs)负载的ITO/MWCNTs-TiO2/ITO复合器件,利用SEM、XPS、UV-Vis光谱等技术对复合样品进行形貌和结构表征,以液相罗丹明B(RhB)的可见光光催化降解为探针反应,评价MWCNTs-TiO2复合薄膜的催化活性.XPS结果表明MWCNTs与TiO2之间没有形成Ti-C键.I-V特性表明负载了MWCNTs的ITO/MWCNTs-TiO2/ITO复合器件的光电流增强.与空白TiO2薄膜相比,MWCNTs-TiO2复合薄膜的可见光光催化降解RhB的速率提高了3.2倍.MWCNTs并没有掺杂到TiO2晶格中,而是起到了类似光敏剂的作用,可在可见光激发下将导带电子转移到TiO导带上,经一系列反应降解RhB有机物.     

Photoelectron Properties and Organic Molecules Photodegradation Activity of Titania Nanotubes with CuxO Nanoparticles Heat Treated in Air and Argon

Titania is very famous photocatalyst for decomposition of organic pollutants. Its photocatalytic properties significantly depend on the morphology and chemical composition of the samples. Herein, the TiO₂ nanotubes/Cu_xO nanoheterostructures have been synthesized and the effect of heat treatment performed in molecular atmospheres of air and argon on their photoelectrochemical and photocatalytic properties has been studied. The prepared samples have a higher reaction rate constant compared to TiO₂ nanotubes in the decomposition reaction of methylene blue molecules. It is established that in argon treated nanoheterostructures, the copper oxide is present in two phases, CuO and Cu₂O, while in air treated ones there is only CuO. In the TiO₂ nanotubes/Cu_xO samples, Cu²⁺ ions and molecular O₂⁻ radicals were detected while in TiO₂ nanotubes only carbon dangling bond defects are present. The dynamics of O₂⁻ radicals under illumination are discussed. It was shown that the TiO₂ nanotubes do not exhibit photocatalytic activity under visible light. The mechanism of the photocatalytic reaction on the surface of the TiO₂ nanotubes/Cu_xO samples was proposed. It is assumed that a photocatalytic decomposition of organic molecules under visible light at the surface of the nanoheterostructures under investigation is realized mainly by the reaction of these molecules with photogenerated O₂⁻ radicals. The results obtained are completely original and indicate the high promise of the prepared photocatalysts.     

Improvement the wastewater purification by TiO2 nanotube arrays: The effect of etching-step on the photo-generated charge carriers and photocatalytic activity of anodic TiO2 nanotubes

The current study demonstrates how the etching step in anodization process effects on the photocatalytic activity of TiO₂ nanotubes. In this regard, the TiO₂ nanotubes were made by one-step and two-step anodization process on two different substrates Ti and etched-Ti foils, respectively. The results revealed that two-step anodization process is a beneficial way to prepare highly well-organized structure and regular surface. The two-step anodization by an enhancement in the fluoride ions diffusion led to a decrease in nanotubes' porosity and an increment in the nanotubes’ surface area, a factor of roughness, and the ratio of length to diameter, respectively. As a consequence of the improvement in geometrical properties, the two-step TiO₂ nanotubes led to the intensification of photocurrent density (from 0.383 to 0.677 mA cm⁻²⁾ and photoconversion efficiency (from 0.18% to 0.29%) in comparison with the one-step nanotubes, respectively. Further, a synergetic impact of the photoelectrochemical measurement and photocatalytic process was observed. The degradation efficiencies of 2,4-dichlorophenol by two-step nanotubes increased from 47 to 55% under visible light, and from 58 to72% under UV irradiation, which it was attributed to more light harvesting, more photo-generated electrons, higher separation efficiency and improvement in geometrical properties. Furthermore, the kinetic study showed that the reactions follow first-order kinetics and the reaction rate constants by two-step nanotubes are 1.25 and 1.44 times as great as those of one-step nanotubes under visible and UV irradiation, respectively. Moreover, the reusability tests showed that 2-step TiO₂ nanotubes has good stability and is active even up to the Fifth run.