Ag/TiO_(2-x)N_x纳米管的光电催化性能

在0.5wt%NaF+1mol/L Na2SO4溶液中,20V电压下,通过阳极氧化的方法,在纯Ti片表面制备出与基底垂直、排列整齐有序的TiO2纳米管,将制得的TiO2纳米管在500℃、氨气的气氛下退火2h,然后,在0.5mol/L AgNO3溶液中用12W的紫外灯照射24h,制备出Ag/TiO2-xNx纳米管,并用XRD,SEM和XPS进行表征.实验结果显示,在紫外光下,Ag/TiO2-xNx纳米管的光电催化降解效率比TiO2纳米管的光电催化降解效率提高了39.68%;在可见光下,Ag/TiO2-xNx纳米管的光电催化降解效率比TiO2-xNx纳米管可见光光电催化的降解效率提高了12%.可见光光电催化16h后,初始浓度为10×10-6mol/L的亚甲基蓝降解率达到50.53%.     

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.     

TA10表面纳米管阵列的制备及其光电化学性能

本文采用阳极氧化法,选用TA10(Ti-0.3Mo-0.8Ni)合金为原料,在反应过程中将Mo和Ni金属元素进行原位掺杂。在不同电压和不同时间两种试验因素下,探索了生成纳米管阵列的最佳电压和时间。采用扫描电子显微镜(SEM)观察纳米管阵列的形貌,X射线衍射仪(XRD)分析物相组成,以及电化学工作站测试动电位(I-V),光电流响应(i-t)和光电压响应(U-t)曲线。结果表明,在阳极氧化电压为20V,时间为1h的条件下纳米管阵列表现为最佳形貌,物相组合也为最佳。此时,饱和光电流密度为0.65mA·cm-2,光转换效率为0.37%。     

电解液组分对阳极氧化法制备TiO_2纳米管的影响

在不同电解液组分中采用阳极氧化法制备了不同结构参数的TiO2纳米管,考察了不同电解液组分对TiO2纳米管形貌和尺寸参数的影响.采用场发射扫描电子显微镜(SEM)和X射线衍射仪(XRD)对纳米管的形貌和结构进行了表征,并分析了电解液组分对纳米管生长的影响机制.结果表明,降低电解液中H+浓度以及减少电解液中H2O的含量可有效提高纳米管的长度.     

TiO_2/ZnO纳米管的制备及其光催化性能

采用电化学阳极氧化法制备了高度有序的TiO2纳米管阵列,并利用纳米管的光致超亲水特性,采用斜面毛细组装技术在无定形TiO2表面自组装ZnO溶胶后退火制备了TiO2/ZnO复合纳米管.探讨了阳极氧化各参数对纳米管形貌的影响.利用X射线衍射仪(XRD)、场发射扫描电子显微镜(FE-SEM)等方法对样品的结构和形貌进行了表征.以有机磷农药氯胺磷为光催化降解对象,研究了焙烧温度、管径、管长和TiO2/ZnO复合比例等因素对降解效果的影响.结果表明,焙烧温度、管径以及ZnO复合比例对光催化降解率影响较大.对于管径97 nm、管长315.8nm的TiO2/ZnO纳米管,ZnO最佳复合比例为4.2%(质量分数),5 h后降解率达到78%.     

High efficiency dye-sensitized solar cells based on hierarchically structured nanotubes

Dye-sensitized solar cells (DSSCs) based on hierarchically structured TiO(2) nanotubes prepared by a facile combination of two-step electrochemical anodization with a hydrothermal process exhibited remarkable performance. Vertically oriented, smooth TiO(2) nanotube arrays fabricated by a two-step anodic oxidation were subjected to hydrothermal treatment, thereby creating advantageous roughness on the TiO(2) nanotube surface (i.e., forming hierarchically structured nanotube arrays-nanoscopic tubes composed of a large number of nanoparticles on the surface) that led to an increased dye loading. Subsequently, these nanotubes were exploited to produce DSSCs in a backside illumination mode, yielding a significantly high power conversion efficiency, of 7.12%, which was further increased to 7.75% upon exposure to O(2) plasma.     

F含量对ZrO2纳米管形貌和相组成的影响

采用阳极氧化法在丙三醇+NH₄F+5vol% H₂O的电解液中制备了高度有序的ZrO₂纳米管阵列, 详细考察了溶液中F含量(0.1~1.1 mol/L)对纳米管形貌﹑相结构和化学组成的影响. 利用扫描电子显微镜(SEM), X射线衍射仪(XRD)和X射线光电子能谱仪(XPS)对不同条件下制备的管径约90~130 nm, 管长约4.8~9.1 μm的纳米管形貌和结构进行了表征. 结果显示, 在含有0.7 mol/L NH₄F的电解液中获得了高度有序且垂直导向的四方相ZrO₂纳米管阵列, 而在较低浓度的电解液中制备的纳米管阵列为无定形结构, 较高浓度下纳米管阵列出现坍塌. 此外, 纳米管近表层处F/O原子比也随F^-浓度的变化而变化.     

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.     

Phenomena of nanotube nucleation and growth on new ternary titanium alloys

Ti-30Nb-xZr and Ti-30Ta-xNb alloys have been investigated using various methods of surface nanotube formation. Ternary Ti-30Nb-xZr (x = 3 and 15 wt%) and Ti-30Ta-xNb (x = 3 and 15 wt%) alloys were prepared by using high-purity sponge Ti (Grade 4, G&S Titanium, USA), Ta, Zr and Nb spheres. The two groups of ternary Ti alloys were prepared using a vacuum arc melting furnace. Nanotube formation was carried out with a conventional three-electrode configuration with the Ti alloy specimen, a platinum counterelectrode, and a saturated calomel (SCE) reference electrode. Experiments were performed in 1 M H3PO4 with small additions of NaF (0.1-0.8 wt%), using a potentiostat. Nanotubes formed on the surfaces of the two ternary Ti alloys were examined by field emission scanning electron microscopy, EDS and XRD. The Ti-30Ta-xZr alloys had microstructure with entirely needle-like constituents; the thickness of the needle-like alpha-phase increased as the Zr content increased. The Ti-30Nb-xZr alloys had equiaxed microstructures of the beta-phase, and increasing amounts of the needle-like alpha phase appeared at the grain boundaries of the beta-phase as the Zr content increased. The nanotubes were nucleated and grew mainly on the beta phase for the Ti-30Ta-3Zr and Ti-30Nb-3Zr alloys, which had nanotubes with uniform shape, but the nanotubes were nucleated at the alpha phase for the Ti-30Ta-15Zr and Ti-30Nb-15Zr alloys, which had nanotubes with irregular shape and diameters of two sizes. The diameter and depth of the nanotubes could be controlled, depending upon the alloy composition and composition of the surface oxide films (TiO2, Nb2O5, Ta2O5, and ZrO2). It is concluded that this research that selection of the appropriate alloying element can allow significant control of the nanotopography of these Ti alloy surfaces and that it is possible to control the surface nanotube size to promote long-term osseointegration for clinical dental or orthopedic use.     

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.     

Fabrication and characterization of self-organized mixed oxide nanotube arrays by electrochemical anodization of Ti-6Al-4V alloy

Self-organized mixed oxide nanotube arrays were fabricated by anodization of Ti-6Al-4V alloy in H₃PO₄/NH₄F aqueous solution. The nanotubes of 90-180 nm in diameter and 10-20 nm in wall thicknesses could be tuned by changing anodization voltages. Whereas, the as-prepared nanotube arrays were amorphous; to induce crystallinity, the products were annealed at 400 °C, 500 °C and 600 °C, respectively. The UV-Vis spectra of samples annealed at 600 °C gives the maximum absorption in the visible spectra range. Various characterization techniques (viz., FESEM, XPS, XRD, and UV-Vis) were used to study the morphology, composition, phase and band gap of the films.     

Effect of sputtered TiAlCr coatings on oxidation and hot corrosion resistance of Ti-24Al-14Nb-3V

The effect of sputtered Ti-50Al-10Cr and Ti-50Al-20Cr coatings on both isothermal and cyclic oxidation resistance at 800 similar to 900 degreesC and hot corrosion resistance at 850 degreesC of Ti-24Al-14Nb-3V was investigated. Results indicated that Ti-24Al-14Nb-3V alloys exhibited poor oxidation resistance due to the formation of Al2O3+TiO2+AlNbO4 mixed scales in air at 800 similar to 900 degreesC and poor hot corrosion resistance due to the spallation of scales formed in Na2SO4+K2SO4 melts at 850 degreesC. Both Ti-50Al-10Cr and Ti-50Al-20Cr coatings remarkably improved the oxidation and hot corrosion resistance of Ti-24Al-14Nb-3V alloy.     

Efficient inverted solar cells using TiO(2) nanotube arrays

Using a vertical titania (TiO(2)) nanotube array, an inverted polymer solar cell was constructed with power conversion efficiency up to 2.71%. In this study, self-organized TiO(2) nanotubes arrays were grown by anodizing Ti metal in glycerol electrolyte containing 0.5?wt% NH(4)F and 1.0?wt% H(2)O with 20?V potential. The tube length (～100?nm) was controlled by the thickness of the sputtered titanium layer on the indium-tin oxide (ITO) substrate. The diameter of the tube was approximately 15-25?nm. After annealing in air at 500?°C for 1?h, nanotubes arrays were crystallized to the anatase phase from the initial amorphous state. Following the infiltration of polymeric semiconductor (poly(3-hexylthiophene) and (6,6)-phenyl C(60) butyric acid methyl ester, P3HT:PCBM), the filled TiO(2) layer had an optical absorption over a range from UV to visible light. The high surface-to-volume ratio of the nanotube arrays structure increased the effective area of the active region. The high efficiency of our solar cell is attributed to the vertical TiO(2) nanotube array's enhanced conduction of photo-induced current due to its charge transport capability.     

Mechanism of surface modification of a porous-coated Ti-6Al-4V implant fabricated by electrical resistance sintering

A porous-coated Ti-6Al-4V implant was fabricated by electrical resistance sintering, using 480 F capacitance and 1.5 kJ input energy. X-ray photoelectron spectroscopy (XPS) was used to study the surface characteristics of the implant material before and after sintering. There were substantial differences in the content of O and N between as-received atomized Ti-6Al-4V powders and the sintered prototype implant, which indicates that electrical resistance sintering alters the surface composition of Ti-6Al-4V. Whereas the surface of atomized Ti-6Al-4V powders was primarily TiO₂, the surface of the implant consisted of a complex of titanium oxides as well as small amounts of titanium carbide and nitride. It is proposed that the electrical resistance sintering process consists of five stages: stage I – electronic breakdown of oxide film and heat accumulation at the metal-oxide interface; stage II – physical breakdown of oxide film; stage III – neck formation and neck growth; stage IV – oxidation, nitriding, and carburizing; and stage V – heat dissipation. The fourth stage, during which the alloy repassivates, is responsible for the altered surface composition of the implant.     

载铂TiO2纳米管的制备与表征

对在TiO2纳米管表面上沉积铂进行了研究．HRTEM、XPS结果表明：第一步沉积在粉末TiO2表面上的铂粒为纳米尺寸，系由PtO2和Pt(OH)2组成；第二步制成纳米管后，铂粒在纳米管外表面分布均匀．为下一步以TiO2纳米管作为催化剂载体的研究奠定了基础．     

Fast fabrication of long TiO2 nanotube array with high photoelectrochemical property on flexible stainless steel

Oriented highly ordered long TiO2 nanotube array films with nanopore structure and high photoelectrochemical property were fabricated on flexible stainless steel substrate (50 microm) by anodization treatment of titanium thin films in a short time. The samples were characterized by means of field emission scanning electron microscopy (FESEM), X-ray diffraction (XRD) and photoelectrochemical methods, respectively. The results showed that Ti films deposited at the condition of 0.7 Pa Ar pressure and 96 W sputtering power at room temperature was uniform and dense with good homogeneity and high crystallinity. The voltage and the anodization time both played significant roles in the formation of TiO2 nanopore-nanotube array film. The optimal voltage was 60 V and the anodization time is less than 30 min by anodizing Ti films in ethylene glycerol containing 0.5% (w) NH4F and 3% (w) H2O. The growth rate of TiO2 nanotube array was as high as 340 nm/min. Moreover, the photocurrent-potential curves, photocurrent response curves and electrochemical impedance spectra results indicated that the TiO2 nanotube array film with the nanoporous structure exhibited a better photo-response ability and photoelectrochemical performance than the ordinary TiO2 nanotube array film. The reason is that the nanoporous structure on the surface of the nanotube array can separate the photo electron-hole pairs more efficiently and completely than the tubular structure.     

Ti-48Al-2Cr-2Nb钝化膜的电化学性能及形成机理

探究Ti-48Al-2Cr-2Nb合金钝化膜的耐腐蚀性和形成机理对提高电解加工过程中的抗杂散腐蚀具有重要意义。通过极化曲线确定了Ti-48Al-2Cr-2Nb合金的钝化电位,采用X射线光电子能谱确定了钝化膜的成分与结构,并运用电化学阻抗谱和Mott-Schottky理论分析了钝化膜的电化学性能。结果表明,Ti-48Al-2Cr-2Nb合金在NaNO3电解液中钝化电位区间为0.079～1.896V,钝化膜主要成分为Al₂O₃、TiO₂及少量的Nb₂O₅,呈双层多孔结构,具有良好的耐腐蚀性。钝化膜具有n型半导体特性,载流子密度随钝化电位的增加而降低。最后,构建了钝化膜形成示意图,揭示了Ti-48Al-2Cr-2Nb合金钝化膜的形成机理与成相膜理论相符,以半球体模型延展并形成独立的相。     

An innovative approach to synthesize highly-ordered TiO2 nanotubes

An innovative route to prepare highly-ordered and dimensionally controlled TiO2 nanotubes has been proposed using a mild sonication method. The nanotube arrays were prepared by the anodization of titanium in an electrolyte containing 3% NH4F and 5% H2O in glycerol. It is demonstrated that the TiO2 nanostructures has two layers: the top layer is TiO2 nanowire and underneath is well-ordered TiO2 nanotubes. The top layer can easily fall off and form nanowires bundles by implementing a mild sonication after a short annealing time. We found that the dimensions of the TiO2 nanotubes were only dependent on the anodizing condition. The proposed technique may be extended to fabricate reproducible well-ordered TiO2 nanotubes with large area on other metals.     

Self-organized TiO2 nanotube arrays: synthesis by anodization in an ionic liquid and assessment of photocatalytic properties

Self-organized TiO(2) nanotube (NT) arrays were produced by anodization in ethylene glycol (EG) electrolytes containing 1-n-butyl-3-methyl-imidazolium tetrafluoroborate (BMI.BF(4)) ionic liquid and water. The morphology of the as-formed NTs was considerably affected by changing the anodization time, voltage, and water and ionic liquid electrolyte concentrations. In general, a nanoporous layer was formed on the top surface of the TiO(2) NTs, except for anodization at 100 V with 1 vol % of BMI.BF(4), where the NT's mouth was revealed. The length and bottom diameter of the NTs as well as the pore diameter of the top layer showed a linear relationship with increased anodization voltage. These TiO(2) NTs were tested as photocatalysts for methyl orange photodegradation and hydrogen evolution from water/methanol solutions by UV light irradiation. The results show that the TiO(2) NTs obtained by anodization in EG/H(2)O/BMI.BF(4) electrolytes are active and efficient for both applications.