形貌对锐钛矿型TiO_2纳米管薄膜光催化性能的影响

采用阳极氧化法在纯钛表面制备了5组平均内径不同以及5种管长不同的TiO2纳米管阵列薄膜,应用SEM对管径进行了表征.将之烧结成锐钛矿型后通过光催化降解甲基橙溶液研究管径与管长的大小对其光催化活性的影响,通过重复催化实验研究其重复使用的效果.结果表明:管径为100nm时催化剂催化降解甲基橙的效果最好,管长则基本不影响纳米管薄膜的催化活性.重复催化实验表明,TiO2纳米管薄膜有很好的重复使用效果.     

阳极氧化时间对二氧化钛纳米管阵列形貌的影响

采用电化学阳极氧化法,以乙二醇体系作为电解液,在60V的直流电压下,在纯钛基底表面制备高度有序的TiO2纳米管阵列,通过改变氧化时间来探究其对TiO2纳米管阵列形貌的影响。运用XRD、SEM分别对TiO2纳米管阵列的结构、形貌特征进行表征。结果表明,氧化时间对TiO2纳米管的管壁厚度、管径以及管长均有影响;氧化时间为2～2.5h时,所得到的二氧化钛纳米管管壁约为10nm、管径约为200nm、管长为2～3μm。     

甘油/DMF混合体系中TiO2纳米管阵列的制备及表征

采用电化学阳极氧化法,以甘油/DMF混合溶液为电解质,在纯钛表面制备了一层排列紧密、结构规整的TiO2纳米管阵列。讨论了氧化电压、电解液中DMF比例、电解液中水含量和电解液重复使用对TiO2纳米管阵列形貌的影响,并且从阳极氧化过程中电流-时间曲线出发分析了混合体系中阳极氧化的形成特征。研究表明,氧化电压越高所制备的纳米管管径越大,但是管长与氧化电压之间不呈线性关系;电解液中DMF比例增加不利于纳米管形成;电解液中水含量越高,纳米管管径越大,表面的覆盖物越多,最佳的水含量为1%(体积分数)。经450℃热处理2h后TiO2纳米管阵列的结构由无定形转变为锐钛矿型。     

TiO2纳米管的结构特征对其光电催化性能的影响

研究了利用电化学阳极氧化法在不同的氧化电压和氧化时间条件下制备的TiO2纳米管(TNT)的结构特征对其光电催化性能的影响。运用场发射扫描电子显微镜,X射线衍射和X射线光电子能谱分析等手段对其进行表征,考察了其光电化学性质,研究了具有不同纳米结构特征的TiO2纳米管降解甲基橙染料废水的反应动力学性能。结果表明,TiO2纳米管的长径比对其光电催化性能影响最大。其管长和管径随着氧化电压和氧化时间的增大而增大,壁厚随着氧化电压的增大而减小。在其管长为25.85μm、壁厚为10.23nm、长径比为178、粗糙系数为175的条件下具有最大光电流密度4.8×10-2 mA/cm2,对甲基橙(MO)光电催化降解拟一级反应动力学常数达到最大值2.26×10-3/min。     

银改性阳极氧化TiO2纳米管及光催化性能研究

利用电化学阳极氧化法在钛片表面制备了TiO2纳米管,以SEM、XRD对其形貌结构进行表征,采用光还原沉积法在硝酸银溶液中得到了Ag/TiO2纳米管,并研究了改性前后TiO2纳米管对甲基橙溶液的光降解能力.结果表明,最佳氧化电压为25V、氧化时间为20min、煅烧温度为500℃.最佳硝酸银溶液浓度为0.2mol/L,最佳光还原时间为60min,光降解率为99％.沉积Ag颗粒大小在10～20nm间,且改性后的光催化性能有很大提高,30min时降解率达到改性前的两倍.     

阳极氧化法制备TiO2纳米管的pH值参数研究

采用电化学阳极氧化法在HF水溶液体系中对钛金属进行表面处理,得到高度规整的TiO2纳米管阵列.主要研究了电解液pH值大小对TiO2纳米管阵列形貌(管径及管长)的影响;用扫描电子显微镜(SEM)对其表面形貌进行表征.结果表明:酸性条件下能形成TiO2纳米管;强碱性环境不利于TiO2纳米管的制备;在可制备TiO2纳米管的pH值范围内,管径和管长随pH值升高而减小.采用微孔模型对pH值的影响机理进行了阐述.     

V掺杂TiO2纳米管阵列的制备及光催化研究

以钒钛合金为原料,应用阳极氧化法制备出高度致密、有序的V掺杂TiO2纳米管阵列。应用扫描电镜(SEM)和粉末X光衍射仪(XRD)表征分析纳米管阵列的形貌和结构,结果表明在浓度不同的HF电解液下制备出径向不同的纳米管阵列,电解液浓度(0.5%～1.5%(质量分数)),管径变化(39.7～72.7nm)。在室温、可见光照射条件下,以10mg/L的亚甲基蓝溶液为模拟污染物进行光催化降解试验,研究了其光催化性能。结果显示V掺杂TiO2纳米管阵列光催化性能优于纯TiO2纳米管,且在HF电解液浓度为1.0%(质量分数)时制备出来的TiO2纳米管光催化降解有机毒物性能最佳。     

不同阳极氧化条件下TiO_2纳米管阵列的制备及表征

分别在三种不同的电解液中,以钛为基体采用阳极氧化的方法制备了TiO2纳米管阵列薄膜,用SEM观察纳米管阵列薄膜的形貌、测量纳米管管径大小;用XRD、拉曼光谱检测TiO2纳米管阵列薄膜热处理前后的晶型.结果表明:不同的电解液体系和氧化电压下得到的纳米管形貌各不相同.在0.24wt%HF水溶液中得到的TiO2纳米管排列整齐,管径为110nm;在0.5wt%NaF+2.7wt%Na2SO4水溶液和0.88wt%NH4F的丙三醇-水(体积比1:1)混合溶液中得到的纳米管排列不规整,管径为100nm;在0.24wt%HF条件下生成的TiO2纳米管管径与氧化电压成线性关系:d=k×U+b,其中,系数k=5.2nm/V,b=2.2nm,0≤U≤25V.经450℃热处理2h后TiO2纳米管结构由无定形态转变为锐钛矿.     

阳极氧化电压对TiO2纳米管阵列生长及场发射性能的影响

室温下在HF水溶液中,利用阳极氧化法在纯钛表面制备了规则有序的TiO2纳米管阵列,应用场致发射扫描电子显微镜、X射线光电子能谱对纳米管阵列表面形貌、断面结构及元素组成进行表征,并对所得样片的场发射性能进行测试,研究了阳极氧化电压对TiO2纳米管阵列形貌及场发射性能的影响.结果表明:在一定范围内增大氧化电压,可增大纳米管的管径、壁厚和管长,但壁厚变化比较小.随着氧化电压的增大,开启场强先降低后增大.当氧化电压为10 V时,所获得的TiO2纳米管阵列开启场强最低,为3.15 V/μm,在6h内8 V/μm电场下保持了稳定的场发射,电流密度为0.85 mA/cm2.     

用乳酸溶液为电解质制备TiO2纳米管阵列

为了开发自组织阳极氧化制备TiO2纳米管阵列的新体系,以乳酸/NH4F混合溶液为电解质,研究了阳极氧化制备TiO2纳米管阵列的影响因素及形成机理.采用X射线衍射(XRD)和扫描电子显微镜(SEM)对样品进行检测,并通过观察阳极氧化过程中的电流-时间变化曲线,探讨TiO2纳米管阵列的形成机理.结果表明:阳极氧化电压、时间及电解质溶液的黏度是影响TiO2纳米管阵列结构和形貌的主要因素,在40 v阳极氧化电压下,制备出平均管径高达180 nm的纳米管,所获得的TiO2纳米管阵列为无定型结构,300℃热处理以后转变为锐钛矿型TiO2.     

Preparation and photoelectrocatalytic activity of ZnO nanorods embedded in highly ordered TiO(2) nanotube arrays electrode for azo dye degradation

In this article, the ZnO nanorods embedded in highly ordered TiO(2) nanotube arrays (ZnO/TiO(2) NR/Ts) electrodes were fabricated through two steps: (1) electrosynthesis of TiO(2) nanotube arrays (TiO(2) NTs) in HF solution by anodization method; (2) followed by cathodic electrodeposition of ZnO embedded in the TiO(2) nanotube arrays. The morphological characteristics and structures of ZnO/TiO(2) NR/Ts electrodes were examined by field-emission scanning electron microscopy (FE-SEM), energy dispersive X-ray (EDX) spectroscopy, X-ray diffraction (XRD) analysis, and UV-vis spectra. The linear-sweep photovoltammetry response on the ZnO/TiO(2) NR/Ts electrode was presented and the photocurrent was dramatically enhanced on the ZnO/TiO(2) NR/Ts electrode, comparing with that on bare TiO(2) NTs electrode. The photocatalytic and photoelectrocatalytic activity of ZnO/TiO(2) NR/Ts electrode was evaluated in degradation of methyl orange (MO) in aqueous solution.     

Enhanced photoelectrochemical cell property from alpha-Fe2O3 nanoparticle decoration on vertically grown TiO2 nanotubes arrays

TiO2 nanotube arrays decorated with alpha-Fe2O3 were prepared by forming a nanotube-like TiO2 film on a Ti sheet using an anodization process, followed by electrochemical deposition to decorate hematite (alpha-Fe2O3) nanoparticles on the TiO2 nanotube arrays. The SEM and XRD results revealed that the alpha-Fe2O3 nanoparticles were homogeneously embedded on the surface of the TiO2 nanotube arrays. The photoelectrochemical properties of the alpha-Fe2O3/TiO2 nanotube arrays as photoanode were studied by photocurrent-potential behavior in 1 M NaOH electrolyte under 100 mW/cm2 UV-Visible light irradiation. Also, the length dependence of TiO2 nanotubes and the amount dependence of alpha-Fe2O3 nanoparticles on the photocatalytic ability were studied and thus the optimum conditions were determined.     

Visible light photoelectrochemical performance of W-loaded TiO2 nanotube arrays: structural properties

Well aligned TiO2 nanotubes were successfully synthesized by anodization of Ti foil at 60 V in a fluorinated bath comprised of ethylene glycol with 5 wt% of NH4F and 5 wt% of H2O2. In order to enhance the visible light absorption and photoelectrochemical response of pure TiO2 nanotube arrays, a mixed oxide system (W-TiO2) was investigated. W-TiO2 nanotube arrays were prepared using radio-frequency (RF) sputtering to incorporate the W into the lattice of TiO2 nanotube arrays. The W atoms occupy the substitutional position within the vacancies of TiO2 nanotube arrays. The as-anodized TiO2 is amorphous in nature while the annealed TiO2 is anatase phase. The mixed oxide (W-TiO2) system in suitable TiO2 phase plays important roles in efficient electron transfers due to the reduction in electron-hole recombination. In this article, the effect of the sputtered W into the as-anodized/annealed TiO2 nanotube arrays on the photoelectrochemical response was presented.     

Fabrication of 3D interconnected porous TiO2 nanotubes templated by poly(vinyl chloride-g-4-vinyl pyridine) for dye-sensitized solar cells

Porous TiO(2) nanotube arrays with three-dimensional (3D) interconnectivity were prepared using a sol-gel process assisted by poly(vinyl chloride-graft-4-vinyl pyridine), PVC-g-P4VP graft copolymer and a ZnO nanorod template. A 7 μm long ZnO nanorod array was grown from the fluorine-doped tin oxide (FTO) glass via a liquid phase deposition method. The TiO(2) sol-gel solution templated by the PVC-g-P4VP graft copolymer produced a random 3D interconnection between the adjacent ZnO nanorods during spin coating. Upon etching of ZnO, TiO(2) nanotubes consisting of 10-15 nm nanoparticles were generated, as confirmed by wide-angle x-ray scattering (WAXS), energy-filtering transmission electron microscopy (EF-TEM) and field-emission scanning electron microscopy (FE-SEM). The ordered and interconnected nanotube architecture showed an enhanced light scattering effect and increased penetration of polymer electrolytes in dye-sensitized solar cells (DSSC). The energy conversion efficiency reached 1.82% for liquid electrolyte, and 1.46% for low molecular weight (M(w)) and 0.74% for high M(w) polymer electrolytes.     

Sol-gel assisted ZnO nanorod array template to synthesize TiO(2) nanotube arrays

A TiO(2) nanotube array with a large surface area is fabricated on a glass substrate using a ZnO nanorod array and sol-gel process, and the structural characteristics of the TiO(2) nanotube array are investigated. The well-aligned ZnO nanorod array, which is deposited on ZnO seed layer coated glass substrates by the wet-chemical route, is used as a template to synthesize TiO(2)/ZnO composite nanostructures through the sol-gel process. Then, by selectively removing the ZnO template, a TiO(2) nanotube with contours of the ZnO nanorods is fabricated on the ZnO seed layer coated glass. The resultant TiO(2) nanotubes are 1.5?μm long and 100-120?nm in inner diameter, with a wall thickness of ～10?nm. In addition, by adjusting the experimental parameters, such as the dip-coating cycle number or heating rate, porous TiO(2) thick films can also be obtained.     

Fabrication of highly ordered TiO2 nanotube arrays via anodization of Ti-6Al-4V alloy sheet

Uniform and highly ordered TiO2 nanotube arrays were fabricated by the electrochemical anodic oxidation on Ti-6Al-4V surface, using graphite plate as cathode and ethylene glycol (EG) with addition of a certain amount of H2O and NH4F as electrolyte, and the anodization voltage went up to a presetting voltage by stepwise increment. The morphology, structure and composition of TiO2 nanotube arrays were characterized by SEM, EDS, XRD and XPS. The formation process of TiO2 nanotubes was introduced in brief. The experiments were arranged by an orthogonal experiment method and the experimental results showed that the formation of TiO2 nanotube arrays was influenced by not only each factor (F- content, H2O content, external voltage and duration), but also cross correlation among the four factors. The optimal condition was F- content 0.2 wt%, H2O content 4 vol%, external voltage 40 V and duration 1 h in the studied electrochemical system, and the length of obtained nanotubes was 1.5 microm, the outer diameter was approximately 100 nm and the aspect ratio was 15. As-formed nanotube arrays were amorphous and changed to anatase TiO2 after annealed at 500 degrees C for 2 h in air ambience. XPS survey spectra revealed the surface of as-formed nanotube arrays containing Ti, O, C, F and N. The nanotube arrays on Ti-6Al-4V surface with better thermo-stability and crystallinity would have great potential in biomaterials.     

Amorphous and crystalline TiO2 nanotube arrays for enhanced Li-ion intercalation properties

We have employed a simple process of anodizing Ti foils to prepare TiO2 nanotube arrays which show enhanced electrochemical properties for applications as Li-ion battery electrode materials. The lengths and pore diameters of TiO2 nanotubes can be finely tuned by varying voltage, electrolyte composition, or anodization time. The as-prepared nanotubes are amorphous and can be converted into anatase nanotubes with heat treatment at 480 degrees C. Rutile crystallites emerge in the anatase nanotube when the annealing temperature is increased to 580 degrees C, resulting in TiO2 nanotubes of mixed phases. The morphological features of nanotubes remain unchanged after annealing. Li-ion insertion performance has been studied for amorphous and crystalline TiO2 nanotube arrays. Amorphous nanotubes with a length of 3.0 microm and an outer diameter of 125 nm deliver a capacity of 91.2 microA h cm(-2) at a current density of 400 microA cm(-2), while those with a length of 25 microm and an outer diameter of 158 nm display a capacity of 533 microA h cm-2. When the 3-microm long nanotubes become crystalline, they deliver lower capacities: the anatase nanotubes and nanotubes of mixed phases show capacities of 53.8 microA h cm-2 and 63.1 microA h cm(-2), respectively at the same current density. The amorphous nanotubes show excellent capacity retention ability over 50 cycles. The cycled nanotubes show little change in morphology compared to the nanotubes before electrochemical cycling. All the TiO2 nanotubes demonstrate higher capacities than amorphous TiO2 compact layer reported in literature. The amorphous TiO2 nanotubes with a length of 1.9 microm exhibit a capacity five times higher than that of TiO2 compact layer even when the nanotube array is cycled at a current density 80 times higher than that for the compact layer. These results suggest that anodic TiO2 nanotube arrays are promising electrode materials for rechargeable Li-ion batteries.     

TiO2纳米管的制备及光催化性能研究

以氟化铵水溶液为电解质,采用阳极氧化法,在钛片基体上制备出TiO2纳米管阵列.用FESEM、XRD等测试方法对样品进行表征,采用UV-1800型紫外-可见分光光度计检测TiO2纳米管对甲基橙的光催化性能.结果表明,氧化电压为50V,氧化时间为10h,煅烧温度为500℃时得到的TiO2纳米管对甲基橙的降解效果最好.     

HF酸电解液浓度对TiO2纳米阵列结构的影响

TiO2纳米阵列(纳米管、纳米棒)结构具有良好的力学性能、化学稳定性以及抗腐蚀性能,在许多技术领域具有广阔的应用前景。采用阳极氧化法在工业纯钛片表面制备出高度有序的TiO2纳米管阵列和纳米棒阵列,研究了电解液浓度和阳极氧化时间对TiO2纳米阵列结构的影响,并对其形成机理进行了初步探讨。结果表明,低浓度的HF酸电解液有利于制备纳米管阵列,高浓度的HF酸电解液有利于制备纳米棒阵列。