一步溶剂热法合成C掺杂介孔TiO_2可见光光催化材料

在无模板剂的条件下,以钛酸四丁酯为钛源,采用一步溶剂热法,在乙醇体系中合成出C掺杂TiO2球状介孔可见光光催化材料.通过X射线粉末衍射(XRD)、扫描电子显微镜(SEM)、透射电子显微镜(TEM)、氮气吸附-脱附仪、X射线光电子能谱(XPS)、固体漫反射(UV-Vis)以及光降解罗丹明B实验等对其进行了结构表征和性能测试.实验结果表明,合成样品为锐钛矿晶型,材料表现为由纳米粒子堆积而成的大小均一的球形形貌.TiO2材料的结晶度和粒子形貌大小可以通过乙酸加入量来进行调控,这对于实际应用具有重要意义.同时,通过测试证明样品中的C原子进入TiO2晶格内部,取代了O原子的位置,窄化了TiO2内部的能带结构,从而大大提高了材料的可见光光催化活性,结果证明合成材料对污染物具有很好的吸附性能和光降解性能.     

TiO_2/Ag_2NCN复合光催化剂的制备与可见光催化性能

利用银盐与单氰胺水溶液的沉淀反应,通过共混不同质量分数的纳米TiO2粒子制备了TiO2/Ag2NCN复合光催化剂.使用X射线衍射仪(XRD)、扫描电子显微镜(SEM)、傅里叶变换红外(FTIR)光谱仪和紫外-可见(UV-Vis)吸收光谱仪对复合光催化剂的结构进行了表征.结果表明,锐钛矿相TiO2纳米颗粒沉积在Ag2NCN表面形成异质结构,二者间以弱的物理作用力相结合.TiO2的掺杂使得复合颗粒的UV-Vis吸收光谱发生红移,带隙变窄.以亚甲基蓝(MB)为光催化降解对象,研究了TiO2/Ag2NCN复合颗粒的可见光催化活性.结果表明,与单一Ag2NCN相比,复合颗粒表现出增强的光催化性能.对TiO2/Ag2NCN复合颗粒的光催化反应动力学过程及光催化机理进行了探讨.     

纳米复合材料Ag/TiO_2-ZrO_2的制备及其微波增强光催化降解甲基橙

采用EO20PO70EO20(P123)作模板剂,通过溶胶-凝胶-程序升温溶剂热一步法,并经萃取处理制备了具有光催化活性的纳米复合材料Ag/TiO2-ZrO2.用X射线衍射(XRD)、X射线光电子能谱(XPS)、透射电子显微镜(TEM)、N2吸附-脱附测定和扫描电子显微镜配合X射线能量色谱仪(SEM-EDS)等测试手段对其组成、结构及形貌等进行了表征.结果表明,复合材料Ag/TiO2-ZrO2中Ag以单质形式存在,材料具有双孔结构,颗粒分布较均匀,结构也较规整,平均孔径约为3.6和9.0nm.通过微波增强光催化降解染料甲基橙的实验,对复合材料Ag/TiO2-ZrO2的光催化活性进行了探究.实验结果表明,微波辅助光催化效果优于紫外辐射,并且萃取后的合成产物Ag/TiO2-ZrO2在90min内对甲基橙的降解率可达81.5%,其活性高于市售P25以及TiO2-ZrO2.     

SnO2/TiO2复合纳米纤维的制备及光催化性能

采用静电纺丝技术,以聚乙烯吡咯烷酮和钛酸正丁酯为前驱体,制得锐钛矿相TiO2纳米纤维。以TiO2纳米纤维为模板,通过水热合成法,制备了具有异质结构的SnO2/TiO2复合纳米纤维。利用扫描电镜(SEM)、X射线能量色散光谱（EDS）、透射电镜(TEM)和X射线衍射(XRD)等分析测试手段对其形貌和结构进行了表征,结果表明,SnO2纳米粒子均匀地生长在TiO2纳米纤维表面,形成了异质结构的SnO2/TiO2复合纳米纤维材料。通过改变反应物浓度,能有效地实现SnO2/TiO2复合纳米纤维的可控合成。以罗丹明B为模拟污染物,考察了SnO2/TiO2复合纳米纤维的光催化性能,与纯TiO2纳米纤维相比光催化活性明显提高,初步探讨了光催化反应机理。     

电纺丝合成树枝状Ag-TiO2复合材料及光催化降解有机物

通过高压电纺丝方法合成TiO2纳米纤维, 以此为模板构建树枝状Ag-TiO2复合材料. 采用 X 射线衍射与扫描电镜对该材料进行结构与形貌表征. 与商品化的TiO2(P25)及TiO2纳米纤维相比, 该复合材料在亚甲基蓝的光催化降解过程中表现出更优异的催化性能.     

异质结型Er2O3/TiO2复合纳米纤维制备及光催化性能

采用静电纺丝技术与溶剂热法相结合,制备了异质结型Er2O3/TiO2复合纳米纤维光催化材料。利用X射线衍射(XRD)、扫描电镜(SEM)、透射电镜(TEM)、高分辨透射电镜(HRTEM)和紫外-可见吸收光谱(UV-Vis)等分析测试手段对材料进行表征,并以罗丹明B(RB)的脱色降解为模式反应,考察了材料的光催化性能。实验结果表明:Er2O3纳米粒子均匀地负载在TiO2纤维上,形成了异质型Er2O3/TiO2复合纳米纤维光催化材料,拓宽了光谱响应范围,有利于TiO2光生电子和空穴的分离,增强了体系的量子效率。与纯TiO2纳米纤维相比光催化活性明显提高,对RB的紫外光降解率达93.93%。     

利用有机助剂提高TiO2光催化产氢和降解性能

采用助催化剂加速光催化材料中空穴-电子对的分离提高光催化效率的有效方法.本文以有机分子草酰胺(OA)作为新型助催化剂来促进TiO2光催化材料的光生载流子分离,从而增强其光催化H2释放和染料降解性能.最佳TiO2-OA复合光催化剂上H2的析出和罗丹明B的光催化效率分别达到2371μmol g–1 h–1和1.43×10–2 min–1,分别是TiO2的2.4和3.8倍.系统研究了光催化增强的可能机理,并提出OA凭借其π-共轭结构作为助催化剂,不仅增强了TiO2的光吸收,而且促进了空穴转移,因而达到了加速电荷分离的效果.利用湿化学法合成了TiO2-OA光催化材料,并采用X射线衍射(XRD)、X射线光电子能谱(XPS)、扫描电子显微镜(SEM)、透射电子显微镜(TEM)、红外光谱(FT-IR)以及紫外-可见漫反射光谱(UV-vis)等表征方法对该催化剂的结构特征、微观形貌和光学性能进行分析,并研究了TiO2-OA复合材料的光催化性能. SEM和TEM结果表明, TiO2-OA呈方形,尺寸约为30nm.OA含量为30wt%的TiO2-OA样品在用于制氢的光催化水分解反应中表现最佳.同时研究了TiO2-OA光催化剂的光催化机理,用对苯醌、乙二胺四乙酸二钠和正丁醇进行了自由基捕捉剂实验.结果表明,羟基自由基在降解有机染料过程中起主要作用.通过光电流测试、材料价带导带位置计算以及·O2和·OH定量实验并结合文献分析认为,掺入具有独特π-共轭结构的OA可以提供空穴转移位点,从而极大地促进TiO2和OA之间光生电子-空穴的分离和转移.本工作可能为构建具有新型有机助催化剂的高效光催化体系开辟了一条新途径.     

三维有序大孔复合材料Ag/TiO2的制备与不同模式下的光催化性能

采用聚苯乙烯(PS)微球和EO20PO70EO20(P123)作为模板剂,通过溶胶-凝胶及煅烧后处理等方法制备了三维有序大孔复合材料Ag/TiO2(3DOM Ag/TiO2).经傅里叶变换红外光谱、X射线衍射、紫外-可见漫反射吸收光谱、X射线光电子能谱、N2吸附-脱附测试和扫描电子显微镜配合X射线能量色散谱等测试手段对其组成、结构及形貌等进行了表征.结果显示,该复合材料的孔结构排列整齐有序,孔壁呈现介孔结构且分布均匀,属于三维有序大孔材料.该3DOM Ag/TiO2具有锐钛矿晶相,其Ag以单质形式存在.与商用光催化剂(Degussa P-25)相比,3DOM Ag/TiO2对光的吸收红移至可见区.考察了3DOM Ag/TiO2在紫外光、可见光以及微波辅助等不同模式下光催化降解有机污染物的性能.结果显示,其活性明显高于P-25和Ag/TiO2,且针对不同类型的有机污染物均表现出较好的光催化性能.     

WO3/TiO2 复合纤维的制备及储能光催化性能

以钛酸正丁酯为前驱体, 采用静电纺丝技术制得了纯锐钛矿TiO2纤维, 并以其为基质, 通过水热法制备了具有异质结构的WO3/TiO2复合纤维. 利用X射线衍射仪(XRD)、 扫描电子显微镜(SEM)、 能量色散光谱仪(EDS)、 透射电子显微镜(TEM)和高分辨透射电子显微镜(HRTEM)等对样品的结构和形貌进行了表征. 以罗丹明B的脱色降解为模型反应, 考察了样品的光催化性能和储能光催化性能. 结果表明, 花状WO3微球包裹在TiO2纤维上, 得到了具有异质结构的WO3/TiO2复合纤维光催化剂. WO3与TiO2复合有利于光生载流子的输运和分离, 增强了体系的量子效率, 提高了光催化活性. WO3/TiO2 复合纤维经光照处理后, 在黑暗条件下显示出储能光催化特性.     

LiF掺杂TiO2的制备及其光催化性能

采用溶胶-凝胶法制备了LiF掺杂的TiO2光催化剂,并采用X射线衍射、X射线光电子能谱和光致发光光谱等技术对样品进行了表征.以亚甲基蓝的光催化降解为反应模型,考察了LiF掺杂量、退火温度和溶液pH值对催化剂光催化性能的影响.结果表明,LiF的掺杂降低了金红石相的形成温度,同时在TiO2表面引入大量羟基氧并提高了TiO2表面氧空穴浓度,因此提高了TiO2的光催化性能.在LiF掺杂量为8%,退火温度为500℃和反应液pH值为6.6的条件下,LiF掺杂的TiO2的光催化活性是未掺杂TiO2的6倍.     

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.     

TiO2纳米管阵列覆盖Si薄膜光催化还原CO2性能的研究

本工作采用CVD法在阳极氧化TiO2纳米管阵列膜表面沉积一层非晶Si膜,通过退火后得到晶化了的Si膜/TiO2纳米管阵列的复合结构,并初步就其光催化还原CO2制备碳氢化合物的活性进行研究。拉曼光谱(Raman)、X射线衍射(XRD)、场发射扫描电镜(FE-SEM)、高分辨透射电子显微镜(TEM)等微结构表征结果表明所制备的TiO2纳米管阵列的厚度为270 nm左右,管直径约为70 nm,管壁厚度约为16 nm。覆盖的Si膜已晶化,其厚度约为300 nm。通过高效液相色谱(HPLC)及总有机碳(TOC)来检测光催化还原液相产物中的甲酸及总有机碳含量,发现负载Si膜后的TiO2纳米管阵列光催化性能有所提高,在装有400cut滤光片氙灯照射2 h下TOC含量从21.2 mg.L-1增长到29.5 mg.L-1,表明Si与TiO2的复合可有效的提高光催化还原CO2的活性,这可能与该异质结结构可增加对光的吸收并且可降低光生空穴-电子对复合有关。光催化循环实验表明所制得的催化剂在循环5次后仍可保持91.6%的催化活性。     

Photocatalytic activity of polyaniline/Fe-doped TiO2 composites by in situ polymerization method

This study was focused on the photocatalytic activity of polyaniline (Pani)/iron doped titanium dioxide (Fe–TiO₂) composites for the degradation of methylene blue as a model dye. TiO₂ nanoparticles were doped with iron ions (Fe) using the wet impregnation method and the doped nanoparticles were further combined with Pani via an in situ polymerization method. For comparison purposes, Pani composites were also synthesized in the presence undoped TiO₂. The photocatalyst and the composites were characterized by standard analytical techniques such as FTIR, XRD, SEM, EDX and UV–Vis spectroscopies. Fe–TiO₂ and its composites exhibited enhanced photocatalytic activity under ultraviolet light irradiation. Improved photocatalytic activity of Fe–TiO₂ was attributed to the dopant Fe ions hindering the recombination of the photoinduced charge carriers. Pani/Fe–TiO₂ composite with 30?wt.% of TiO₂ nanoparticles achieved 28% dye removal and the discoloration rate of methylene blue for the sample was 0.0025?min^?1. FTIR, XRD, SEM, EDX and UV–Vis spectroscopies supported the idea that Fe ions integrated into TiO₂ crystal structure and Pani composites were successfully synthesized in the presence of the photocatalyst nanoparticles. The novelty of this study was to investigate the photocatalytic activity of Pani composites, containing iron doped TiO₂ and to compare their results with that of Pani/TiO₂.     

Pt deposited TiO2 catalyst fabricated by thermal decomposition of titanium complex for solar hydrogen production

C, N codoped TiO₂ catalyst has been synthesized by thermal decomposition of a novel water-soluble titanium complex. The structure, morphology, and optical properties of the synthesized TiO₂ catalyst were characterized by X-ray diffraction, scanning electron microscopy, X-ray photoelectron spectroscopy, and UV–vis diffuse reflectance spectroscopy. The photocatalytic activity of the Pt deposited TiO₂ catalysts synthesized at different temperatures was evaluated by means of hydrogen evolution reaction under both UV–vis and visible light irradiation. The investigation results reveal that the photocatalytic H₂ evolution rate strongly depended on the crystalline grain size as well as specific surface area of the synthesized catalyst. Our studies successfully demonstrate a simple method for the synthesis of visible-light responsive Pt deposited TiO₂ catalyst for solar hydrogen production.     

A comparative study on characterization and photocatalytic activities of gadolinium–boron codoped and mono-doped TiO2 nanoparticles

Gadolinium?Cboron codoped and mono-doped TiO₂ nanoparticles were prepared using a sol?Cgel method, and tested for photocatalytic activity by the UV light after a further calcination process. For comparison, a pure TiO₂ sample was also prepared and tested under the same conditions. The prepared catalysts were characterized by X-ray diffraction, scanning electron microscope, and UV?CVis spectra. The photocatalytic activity of the samples was evaluated through the photo-degradation of three different dyes under UV light. The experiments demonstrated that the gadolinium?Cboron codoped TiO₂ (Gd?CB?CTiO₂) sample calcined at 500?°C possessed the best photocatalytic activity, and the photodegradation rate of the Reactive Brilliant Red K2G aqueous solution could reach to 95.7% under UV irradiation for 80?min. The results showed that Gd?CB?CTiO₂ has smaller crystallite size and higher photocatalytic activity than that of mono-doped TiO₂ samples and undoped TiO₂.     

Preparation and characterization of Zr doped TiO2 nanotube arrays on the titanium sheet and their enhanced photocatalytic activity

This paper described a new method for the preparation of Zr doped TiO₂ nanotube arrays by electrochemical method. TiO₂ nanotube arrays were prepared by anodization with titanium anode and platinum cathode. Afterwards, the formed TiO₂ nanotube arrays and Pt were used as cathode and anode, respectively, for preparation of Zr/TiO₂ nanotube arrays in the electrolyte of 0.1 M Zr(NO₃)₄ with different voltage and post-calcination process. The nanotube arrays were characterized by field-emission scanning electron microscopy (FESEM), X-ray diffraction (XRD), X-ray photoelectron spectra (XPS) and UV-Vis diffusion reflection spectra (DRS). The photocatalytic activities of these nanotubes were investigated with Rhodamine B as the model pollutant and the results demonstrated that the photocatalytic efficiency of Zr doped TiO₂ nanotubes was much better than that of TiO₂ nanotubes under UV irradiation. Zr/TiO₂ nanotube arrays doped at 7 V and calcined at 600 °C (denoted as TiO₂-7 V-600) achieved the best photocatalytic efficiency and the most optimal doping ratio was 0.047 (Zr/Ti). TiO₂-7 V-600 could be reused for more than 20 times and maintained good photocatalytic activities.     

Physical properties of nano-titania hollow fibers and their photocatalytic activity in the decomposition of phenol

A series of nano-titania (TiO₂) photocatalytic materials with a hollow fiber structure were successfully prepared using tetra-n-butyl titanate (Ti(OC₄H₉)₄) as precursor and cotton fiber as the template. Scanning electron microscopy (SEM), X-ray diffraction (XRD), and N₂ adsorption-desorption measurements were employed to characterize the morphology, crystal structure, and surface structure of the samples. The photocatalytic activities of the samples were studied by phenol photodegradation in water under UV irradiation. The effect of calcination temperature, photocatalyst dosage, initial concentration of phenol and irradiation time on the photodegradation of phenol was studied. Results showed that the TiO₂ fiber materials have hollow structures, indicating that these materials had a large specific surface area. The fiber structure material showed better photocatalytic properties for the degradation of phenol than pure TiO₂ under UV light, and the sample calcined at 500°C exhibited the highest phenol photodegradation efficiency. In addition, the possibility of cyclic usage of the photocatalyst was also confirmed, the photocatalytic activity of TiO₂ fiber remained ca. 90% of photocatalytic activity of the fresh sample after being used four times. Moreover, TiO₂ fiber was easily recovered by centrifugal separation from water.     

Characterization of Visible Light Response N-F Codoped TiO2 Photocatalyst Prepared by Acid Catalyzed Hydrolysis

N-F codoped TiO₂ (TONF) photocatalysts were prepared using acid catalyzed hydrolysis method from mixed aqueous solution of TiCl₄ and NH₄F. The photocatalytic activity of the TONF was evaluated through the degradation of phenol under both visible and UV light irradiation. X-ray photoelectron spectroscopy (XPS), UV-Vis diffuse reflectance spectroscopy (DRS), X-ray diffraction (XRD), scanning electron microscope (SEM), and N₂ adsorption isotherm were used to characterize the obtained powders. The results showed that N-F codoped TiO₂ exhibited significant improvement of visible light catalytic activity. N-F codoping could improve dispersion of TiO₂, inhibit particle size agglomeration, and retard phase transformation. Doped N could extend the light response of TiO₂ to visible light region. In addition, narrower band gap formed by F-doping was beneficial to the high visible light photocatalytic activity.     

具有分级多孔结构和光催化性质的核-壳纳米球(HP-Fe2O3@TiO2)

通过溶剂热和溶胶-凝胶涂层法, 设计并制备了具有分级多孔结构和光催化性质的核-壳纳米球(HP-Fe₂O₃@TiO₂). 透射电子显微镜(TEM)照片证明所得HP-Fe₂O₃@TiO₂样品具备分级多孔结构, 这是因为HP-Fe₂O₃@TiO₂的内核-Fe₂O₃具有大孔空隙, 同时外壳-TiO₂具有介孔空隙. 此外, 通过X射线衍射(XRD)、扫描电子显微镜(SEM)、高分辨透射电子显微镜(HRTEM)、X射线光电子能谱(XPS)以及氮气吸附-脱附曲线深入研究了HP-Fe₂O₃@TiO₂的结构及其性质. 分别在可见及紫外光照下, 研究了样品在H₂O₂体系下的光催化降解亚甲基蓝(MB)的性质. 所观察到的HP-Fe₂O₃@TiO₂纳米球的光催化性能, 可归因于核-壳结构的协同作用, 这进一步表明, TiO₂外壳对α-Fe₂O₃的光催化活性有重要影响作用. 在可见光照射下, HP-Fe₂O₃@TiO₂ (1 mL Ti(OC₄H₉)₄ (TBT))具有较优异的光催化活性. 同时, HP-Fe₂O₃@TiO₂ (4mL TBT)具备优异的单分散形貌, 并在紫外光照射下, 表现出最优的光催化活性.     

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。