纳米晶TiO2的形貌对其荧光性能影响的研究

利用溶剂热合成法成功制备出了形貌为准球形、棒形、球棒混合型和菱形,粒径在50nm以下、尺寸均一的锐钛矿型TiO2纳米晶,对合成出的纳米晶TiO2用荧光光谱,紫外/可见光吸收光谱进行光学性能表征,结果表明,TiO2纳米晶在330 nm的激发光下,分别在345 nm、363nm、380nm和402 nm处存在4个发光峰位。在实验中,首次发现和证实了理论计算出的锐钛矿型TiO2纳米晶的两种直接跃迁发光,分别对应为X（1b）→X（2b）（345 nm）和X（1b）→X（1a）（363 nm）,主要因为油酸改变了TiO2纳米晶的{001}晶面族晶面的表面态。TiO2纳米晶的紫外吸收峰位于229 nm,且与其形貌无关;禁带宽度的计算值接近其理论值3.2 eV。     

水热法制备的Ti1-xCoxO2稀磁半导体特性

采用水热法制备出Ti1-xCoxO2(x=0～0.10)稀磁半导体材料,并对其形貌、结构及磁性能进行表征.X射线衍射分析结果表明,纯TiO2样品为锐钛矿相,掺杂Co离子后样品中出现金红石相,当掺杂浓度到0.10时样品中出现Co3O4的衍射峰.透射电镜和X射线能量色散谱测试结果表明,样品形貌规整,平均粒径约为20nm,并且证实样品中含有Co元素.利用振动样品磁强计对其磁性进行测量,结果表明样品在室温条件下存在铁磁性.     

钛酸盐中钠离子含量对其水热转化制备TiO_2纳米材料的影响

采用水热法制备了单晶TiO2纳米材料。用X射线衍射仪和透射电子显微镜对产物的晶相组成和形貌进行了表征。考查了钛酸盐中钠离子含量对其水热转化所得TiO2产物的相组成、形貌和尺寸的影响。当pH值为1,含有钠离子时,得到的是以菱形为主的直径为10nm左右的单晶锐钛矿纳米颗粒,不含钠离子时,得到的产物以单晶锐钛矿纳米颗粒为主,同时含有少量单晶金红石纳米棒。当pH值为4,含有钠离子时,得到的是具有高长径比的单晶锐钛矿纳米棒,宽为60nm左右,长为300～500nm左右,不含钠离子时,得到的是尺寸为20nm×60nm的短纳米棒。同时,探讨了钛酸盐中钠离子的影响机理。     

掺杂纳米TiO_2粉体的制备及其光电性能研究

利用Zn2+离子掺杂纳米二氧化钛,以提高其光电转化性能,通过溶胶-凝胶法制备了Zn2+离子掺杂的纳米二氧化钛粉体,采用X射线衍射、扫描电镜、紫外可见光谱和光诱导产生光电流法对掺杂二氧化钛的物相、形貌、光吸收性能和光电性能进行了表征。研究发现,Zn2+掺杂有利于锐钛矿的结晶,掺杂二氧化钛较纯二氧化钛的紫外吸收边红移了约10nm,当Zn2+掺杂量为Ti物质的量的1%时光电转化性能最佳。     

基底温度对直流溅射Nb掺杂TiO2薄膜性能的影响

采用陶瓷靶直流磁控溅射,以玻璃为基底制备2.5wt%Nb掺杂TiO2薄膜,控制薄膜厚度在300~350 nm,研究了不同基底温度下所制得薄膜的结构、形貌和光学特性.XRD分析表明,基底温度为150℃、250℃和350℃时,薄膜分别为非晶态、锐钛矿(101)和金红石相(110)结构.基底温度250℃时,锐钛矿相薄膜的晶粒尺寸最大,约为32 nm.薄膜表面形貌的SEM分析显示,薄膜粗糙度和致密度随基底温度升高得到改善.薄膜的平均可见光透过率在基底温度为250℃以内约为70%,随基底温度升高至350℃,平均透过率下降为59%,金红石相的存在不利于可见光透过.Nb掺杂TiO2薄膜的光学带宽在3.68~3.78 eV之间变化.基底温度为250℃时,锐钛矿相薄膜的禁带宽度最大,为3.78 eV.     

硫掺杂TiO2的制备及其光催化降解次甲基蓝研究

以TiCl4、(NH4)2SO4为原料,采用溶胶-凝胶法制备了硫掺杂纳米TiO2,利用XRD、TEM、FTIR等对样品进行了表征,并将其用于光催化降解次甲基蓝溶液.结果表明:制备的纳米TiO2为锐钛矿晶型,具有超强酸特征,平均粒径分布为10～30nm,S掺杂对TiO2的晶粒长大有抑制作用,经过硫掺杂的纳米TiO2光催化活性明显优于纯TiO2.     

N、C共掺TiO2光催化剂的制备与性能研究

以三聚氰胺为掺杂源,采用溶胶-凝胶法制得了平均粒径为20.1nm的锐钛矿型N、C共掺TiO2光催化剂.当n(N)∶n(C)∶n(Ti)为0.064∶0.055∶1时,TiO2对亚甲基蓝3h日光降解率可达68%.探讨了三聚氰胺的用量和煅烧温度对TiO2光催化性能的影响,确定了最佳制备工艺.XPS和FTIR分析表明,N主要以替代O的形式生成O-Ti-N,少量N以填隙式生成-Ti-N-O,而C主要以替位式生成O-Ti-C,以填隙式生成-Ti-C-O、-Ti- COOO.UV-Vis分析表明,N、C掺杂TiO2的吸收边从掺杂前的383nm红移到427nm,禁带宽度从掺杂前的3.2eV降到2.9eV,将TiO2的光响应波长拓展到了可见光区.     

稀土元素掺杂TiO2薄膜的制备及其光学性能研究

采用溶胶-凝胶法制备得到Y3 和Ho3 掺杂的TiO2薄膜,XRD分析表明薄膜结晶性能良好,具有锐钛矿晶型。薄膜表面AFM分析表明,薄膜的晶粒具有纳米尺寸。采用紫外-可见分光光度计对掺杂和未掺杂的TiO2薄膜进行紫外-可见吸收光谱分析,表明Y3 和Ho3 掺杂的TiO2薄膜在紫外光区吸光度有所提高,同时在可见光区光吸收范围出现了红移,相同掺杂浓度的Y3 和Ho3 掺杂的TiO2薄膜,前者在400~450nm的可见光区具有更高的吸光度。     

紫外诱导水相条件下Ag修饰TiO2纳米棒的制备及光催化性能

利用贵金属修饰氧化钛被认为是提高氧化钛光催化效率的重要途径。本文提出了一种新的制备方法,利用紫外光诱导还原作用,在水相体系中不使用表面活性剂合成Ag修饰TiO2纳米结构。首先,Ti(SO4)2水解能得到分散良好的锐钛矿相TiO2纳米棒。在TiO2纳米棒合成过程中,利用紫外光的诱导还原作用即可得到Ag/TiO2纳米结构。透射电镜显示Ag修饰TiO2纳米结构是由20～30nm的TiO2纳米棒和10nm左右的Ag"纳米头"组成。对亚甲基蓝的光降解实验证明,Ag/TiO2纳米结构相比纯TiO2在可见光和模拟太阳光下光催化性能分别提高了31倍和3倍。因此,此法合成的Ag/TiO2可被开发用作降解污染物的有效催化剂。     

La掺杂对TiO_2薄膜性能的影响

用溶胶-凝胶法制备TiO2以及La掺杂TiO2的前驱体凝胶,将其均匀旋涂不同层数制备出不同厚度的薄膜,研究了La掺杂对TiO2薄膜结晶性能,表面形貌,光学特性和亲水性能的影响.结果表明:在500℃可以获得结晶性良好的锐钛矿相TiO2薄膜;随着La掺杂量的增加,薄膜中TiO2晶粒会变大,同时引起紫外可见光谱中吸收边的蓝移.掺La的TiO2薄膜经紫外照射后其接触角明显高于未掺杂样品,主要原因是到达表面的活性载流子相对减少.一方面,大的TiO2晶粒使得光生载流子到达光催化表面的路程变长,电子一空穴对的复合几率也随之变大;另一方面,未完全替代Ti的La可能成为光生电子一空穴对的复合中,因此,通过La的掺杂可以有效调节TiO2晶粒尺寸和光致接触角. 能,表面形貌,光学特性和亲水性能的影响.结果表明:在500℃可以获得结晶性良好的锐钛矿相TiO2薄膜;随着La掺杂量的增加,薄膜中TiO2晶粒会变大,同时引起紫外可见光谱中吸收边的蓝移.掺La的TiO2薄膜经紫外照射后其接触角明显高于未掺杂样品,主要原因是到达表面的活性载流子相对减少.一方面,大的TiO2晶粒使得光生载流子到达光催化表面的路程变长,电子一空穴对的复合几率也随 变大;另一方面,未完全替代Ti的La可能成为光生电子一空穴对的复合中,因此,通过La的掺杂可以有效调节TiO2晶粒尺寸和光致接触角     

新型Sb2S3-Sb2Se3与单晶二氧化钛纳米阵列复合结构在太阳能电池领域的应用

近年来,半导体量子点敏化太阳能电池作为新一代的太阳能电池,引起了广泛的关注．Sb2S2和Sb2Se3量子点由于具有出色的光吸收特性与带隙的可调控性,已成为敏化太阳能电池领域的重要组成部分．通过水热法,二氧化钛（TiO2）单晶纳米阵列被成功生长在FTO导电玻璃上．通过连续离子层吸附法（SILAR）,Sb2S3Sb2Se3复合纳米结构被生长在二氧化钛单晶纳米阵列的表面．利用x射线衍射（XRD）表征Sb2S3和Sb2Se3纳米晶体的晶相,利用扫描电子显微镜（SEM）表征其形貌,发现在这一复合结构中,二氧化钛单晶纳米阵列与Sb2S3结合之后所留下的空隙被Sb2Se3量子点填充,从而提高了结构表面积的利用率．随着连续离子层吸附法反应周期的增加,Sb2S3-Sb2Se3,与二氧化钛单晶纳米阵列共同形成复合结构的带隙发生了明显的红移,吸收边在可调控的情况下由1．7eV向红外波段发生了移动．这种纳米结构的比表面积大、工艺简单、结构致密、沉积速率快、可调控性强,对于今后敏化太阳能电池领域的应用有很大的启发作用．     

Synthesis, characterization, and photocatalytic activity of TiO(2-x)N(x) nanocatalyst

Nitrogen-doped titanium dioxide powders were prepared by wet method, that is, the hydrolysis of acidic tetra-butyl titanate using aqueous ammonia solution, followed by calcination at temperatures about 350 degrees C. The catalysts exhibited photocatalytic activity in the visible light region owing to N-doping. The light absorption onset of TiO(2-x)N(x) was shifted to the visible region at 459 nm compared to 330 nm of pure TiO(2). An obvious decrease in the band gap was observed by the optical absorption spectroscopy, which resulted from N2p localized states above the valence band of TiO(2-x)N(x) (compared to TiO(2)). The TiO(2-x)N(x) catalyst was characterized to be anatase with oxygen-deficient stoichiometry by X-ray diffraction (XRD), surface photovoltage spectroscopy (SPS) and X-ray photoelectron spectroscopy (XPS). The binding energy of N1s measured by XPS characterization was 396.6 eV (TiN bonds, beta-N) and 400.9 eV (NN bonds, gamma-N(2)), respectively. The photocatalytic activity of TiO(2-x)N(x) under visible light was induced by the formation of beta-N in the structure. Photocatalytic decomposition of benzoic acid solutions was carried out in the ultraviolet and visible (UV-vis) light region, and the TiO(2-x)N(x) catalyst showed higher activity than pure TiO(2).     

Synthesis and characterization of Co-doped nano-TiO<Subscript>2</Subscript> through co-precipitation method for photocatalytic activity

The aim of this work was synthesis and investigation of various properties of Co-doped titanium dioxide nanostructures. Synthesis was conducted by the co-precipitation method using cobalt nitrate and titanium isopropoxide as a precursor, followed by thermal treatment at a temperature of 500 °C. The materials were fully characterized using several techniques (X-ray diffraction XRD, SEM, FTIR, TGA/DTA, UV–Vis diffuse reflectance DRS and photoluminescence). However, dopant has no effect on XRD pattern of the host but it can influence on the various characteristics of host such as optical and electrical properties. The scanning electron microscopy was used to detect the morphology of synthesized nanoparticles which sizes changed with the altitude in the doping concentration to 6%. FTIR spectra exhibit broad peaks where anatase phases of TiO₂ demonstrate very sharp UV–Vis band gap results showed the reduction in band gap from from 3.21 eV, for undoped TiO₂, to 2.74 eV, for Co doped 6% TiO₂. The photocatalytic activity of the samples were studied based on the degradation of methyl orange as a model compound, where the results showed that Co doped 6% TiO₂ a good photocatalytic activity.     

Photoelectric properties of TiO2-ZrO2 thin films prepared by sol-gel method

Acidic sols of TiO2, ZrO2 and Ti-Zr mixed oxide precursors were prepared. The sols were then smeared on quartz substrate and annealed at 650 degrees C for 2 hour to form polycrystalline oxide films. XRD, SEM, UV-visible absorption spectra and XPS were carried out to characterize the films. It was found that the crystalline phase of pure titania is an anatase and pure zirconia is a tetragonal. The binary oxides show the anatase phase at the molar ratio of Ti:Zr = 2.73:1, which means that solid solution was formed. The absorption edge of the TiO2-ZrO2 binary oxides showed obvious blue shift as the Zr ratio increased. The results obtained indicate that the band gap of the binary oxides could be adjusted from 3.2 eV (TiO2) to 7.8 eV (ZrO2) by varying the molar ratio of Ti and Zr. Au interdigitated electrodes were produced by planar technology and MSM (metal-semiconductor-metal) structure UV detector based on TiO2-ZrO2 binary oxides was fabricated. Obvious photoelectric response was observed.     

钛酸盐一维纳米材料向TiO2纳米材料的水热转化研究

采用强碱性水热处理法分别控制第一次水热反应为160℃和200℃,制备出一维纳米管和纳米棒2种形貌的产物,将其作为第二次水热反应的前驱体,考察了第二次水热体系中pH值和温度对TiO2纳米材料的晶相组成及其微观形貌的影响;采用XRD、TEM以及HRTEM对样品进行了分析.结果表明,当以纳米管为前驱体时,除在pH=0的体系中得到了以金红石相为主的单晶纳米棒外,在pH值为2、4和7的条件下均得到了单晶纯锐钛矿相TiO2纳米颗粒.当以纳米棒为前驱体时,在pH=0的体系中得到了金红石相与板钛矿相共存的纳米棒和纳米颗粒混合产物;在pH值为2、4和7的条件下均得到了纯锐钛矿相TiO2纳米棒;当二次水热温度低于180℃时,前驱体没有转化完全,所得产物为前驱体与锐钛矿相TiO2共存的纳米棒;当水热温度为180℃和210℃时,产物为纯锐钛矿相纳米棒.     

Structural,optical and magnetic properties of cobalt-doped CdS dilute magnetic semiconducting nanorods

Nanostructures of dilute magnetic semiconductors (DMS) in which a part of host material is replaced by a magnetic dopant are the promising candidates for spintronic devices. Pure and cobalt-doped DMS nanorods of CdS have been synthesized by solvothermal method. The effect of doping as well as the size of synthesized nanorods on structural, optical, and magnetic properties has been investigated. Transmission electron microscopy confirms the nanorods' morphology with an average diameter between 7 and 11 nm. Structural study reveals the formation of single phase hexagonal wurtzite structure of CdS with P6₃mc space group. UV–visible absorption spectra confirms that the band gap of the synthesized nanorods lie in the visible region between 2.46 and 2.72 eV. Photoluminescence spectra show defects-free nature of synthesized nanorods. The hump of emission band, around 430 nm in Co-doped CdS nanorods, attributes to the direct transition from the energy states created in CdS. Magnetic study reflects the ferromagnetic character of synthesized nanorods with high magnetic saturation, 0.034, 0.041, 0.070 and 0.090 emu g⁻¹ for, respectively, pure, 5%, 10% and 15% Co-doped CdS nanorods. The observed ferromagnetism in the synthesized nanorods have been explained on the basis of F-center (sulfur vacancy) mediated exchange mechanism and indirect interaction among Co (II) centers.     

纳米TiO2薄膜光催化剂的制备及性能研究

以钛酸四丁酯作为前驱体,用溶胶一凝胶法,在玻璃载体上煅烧制备了纳米TiO2薄膜光催化剂,利用扫描电子显微镜（SEM）、X射线衍射（XRD）等表征技术研究了TiO2薄膜的形貌和特性,其光催化性能用4支20W紫外石英杀菌灯照射TiO2薄膜分解亚甲基兰染料溶液表征,结果表明,该催化剂具有锐钛班红石混合晶相和纳米花状结构,纳米TiO2薄膜的光催化能力随着镀膜层数的增加而增加。     

Effect of cobalt doping on the phase transformation of TiO2 nanoparticles

Co-doped TiO2 nanoparticles containing 0.0085, 0.017, 0.0255, 0.034, and 0.085 mol % Co(III) ion dopant were synthesized via sol-gel and dip-coating techniques. The effects of metal ion doping on the transformation of anatase to the rutile phase have been investigated. Several analytical tools, such as X-ray diffraction (XRD), transmission electron microscope (TEM), X-ray photoelectron spectroscopy (XPS), and energy dispersive X-ray analysis (EDAX) were used to investigate the nanoparticle structure, size distribution, and composition. Results obtained revealed that the rutile to anatase concentration ratio increases with increase of the cobalt dopant concentration and annealing temperature. The typical composition of Co-doped TiO2 was Ti(1-x)Co(x)O2, where x values ranged from 0.0085 to 0.085. The activation energy for the phase transformation from anatase to rutile was measured to be 229, 222, 211, and 195 kJ/mole for 0.0085, 0.017, 0.0255, and 0.034 mol % Co in TiO2, respectively.     

Co-Doped ZnO Nanoparticles:Structural,Morphological,Optical,Magnetic and Antibacterial Studies

Un-doped and Co-doped ZnO nanoparticles （NPs） with different weight ratios （0.5, 1.0, 1.5, and 2.0 wt% of Co） were synthesized by a facile and rapid microwave-assisted combustion method using urea as a fuel. The prepared NPs were characterized by X-ray diffraction （XRD）, high resolution scanning electron microscopy （HR-SEM）, energy dispersive X-ray analysis （EDX）, diffuse reflectance spectroscopy （DRS）, photoluminescence （PL） spectroscopy and vibrating sample magnetometry （VSM）. XRD patterns refined by the Rietveld method indicated that Co-doped ZnO had a single pure phase with wurtzite structure suggesting that Co^2＋ ions would occupy Zn^2＋ ionic sites within the ZnO crystal lattice. Interestingly, the morphology was found to convert substantially from grains to nanoparticles with close-packed periodic array of hexagonal-like shape and then into randomly distributed spherical NPs with the variation of Co-content. The optical band gap estimated using DRS was found to be red-shifted from 3.22 eV for the un-doped ZnO NPs then decrease up to 2.88 eV with increasing Co-content. PL spectra showed a strong green emission band thus confirming the formation of pure single ZnO phase. Magnetic studies showed that Co-doped ZnO NPs exhibited room temperature ferromagnetism （RTFM） and that the saturation magnetization attained a maximum value of 2.203 × 10^-3 emu/g for the highest Co-content. The antibacterial studies performed against a set of bacterial strains showed that the 2.0 wt% Co-doped ZnO NPs possessed a greater antibacterial effect.     

Si掺杂锐钛矿相TiO2的电子能带结构

利用基于密度泛函理论的第一性原理方法对Si掺杂前、后锐钛矿相TiO2的电子能带结构、电子态密度以及吸收光谱进行计算。结果表明,Si掺杂导致锐钛矿相TiO2的禁带宽度略增大0.048 eV;掺杂前锐钛矿相TiO2的价带和导带主要由O的2p和Ti的3d轨道构成,Si掺杂后其价带和导带主要由Si的3p、Ti的4s和Ti的3d轨道构成;Si掺杂可导致锐钛矿相TiO2的吸收边蓝移。