TiO2纳米管阵列薄膜光电协同降解亚甲基蓝的研究

使用阳极氧化法制备了TiO₂/Ti纳米管阵列薄膜材料. TiO₂纳米管管孔分布均匀,管径约为80~90nm,平均管长约为1.8μm. 在400℃下煅烧2h后,TiO₂纳米管阵列为锐钛矿型,并且结构保持良好,没有出现变形、剥落的现象. 以TiO₂/Ti纳米管阵列薄膜材料为光催化剂,同时施加0~+3.0V范围内变化的电场,考察了外加电压对降解亚甲基蓝光电协同效率的影响. 结果表明在外加+1.4V电压的条件下,光电协同效率达到124%. TiO₂纳米管阵列与基底Ti板结合牢固,多次重复使用后没有发现降解率的明显变化.     

高长径比TiO2纳米管阵列的调控制备及其光阳极性能

采用较高粘度的有机溶液作为阳极氧化电解质溶剂制备了TiO₂纳米管阵列. 通过探讨阳极氧化工艺参数对纳米管形貌的影响, 研究出高长径比TiO₂纳米管阵列的制备工艺, 同时对TiO₂纳米管作为染料敏化太阳能电池光阳极的光电性能进行了测试, 并讨论了TiO₂纳米管的形貌对电池性能的影响. 结果表明：提高氧化电压和延长时间有利于获得高长径比纳米管, 在含0.5wt%NH₄F乙二醇电解质中50V氧化17h可制备出长径比为313.6的TiO₂纳米管阵列. TiO₂纳米管(在含0.5wt%NH4F乙二醇电解质中40V氧化13h)作为染料敏化太阳能电池光阳极可得到开路电压为0.723V、短路电流为2.15mA/cm²的光电性能.     

高度有序钛基体阳极氧化钛纳米管阵列的制备与表征

室温下在NH₄F、乙二醇的混合溶液中采用阳极氧化法在纯Ti片表面组装一层结构高度有序且表面光滑的TiO₂纳米管阵列．对TiO₂纳米管阵列进行扫描电子显微镜(SEM)、X射线衍射(XRD)检测; 且检测了TiO₂纳米管(锐钛矿型)在锂离子电池和光催化降解甲基橙等应用性能．结果表明, 制备得到了高密度排列的TiO₂纳米管阵列; TiO₂纳米管在锂离子的脱嵌过程中表现出较好的可逆性质. 溶液中加入H₂O₂可以提高TiO₂纳米管光降解催化活性．     

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.     

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。     

原位合成TiO2纳米管阵列及其光催化性能研究

采用液相沉积法(LPD), 以阳极氧化铝(AAO)为模板, 原位合成高度有序的TiO₂纳米管薄膜材料. 实验结果表明, 经过400℃热处理后, 制备的TiO₂纳米管为锐钛矿相, 长度达5μm, 管外径为150nm左右, 管壁厚为25nm左右. 热处理后的TiO₂薄膜具有良好的光催化降解甲基蓝的性能, 即经过120min卤灯照射后, 甲基蓝被完全降解.     

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。     

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.     

脉冲频率对纯钛微弧氧化膜生长特性的影响

在Na₂CO₃-Na₂SiO₃电解液中, 利用微弧氧化技术在纯钛试样表面制备了氧化膜, 并研究了脉冲频率(500～8000Hz)对膜层生长、相组成及表面形貌的影响. 结果表明: 当脉冲频率<2000Hz时, 膜层的生长速率随频率增加迅速减小, 当>4000Hz时, 其生长速率几乎和频率无关. 微弧氧化膜主要由锐钛矿和金红石相TiO₂及少量不饱和氧化物TiO_2-x(0.022的相对含量与频率无关, 而TiO_2-x随频率的增加而逐渐减少. 氧化膜表面多孔, 随着频率的增加, 膜表面的粗糙度和微孔尺寸逐渐减小, 而微孔的密度逐渐增加.     

钛合金微弧氧化膜微晶生长特性的研究

在Na₂CO₃-NaOH溶液中, 采用自制多功能单极性脉冲微弧氧化电源在TC4钛合金上制备了TiO₂薄膜. 利用XRD和SEM分别对氧化膜的相组成和表面形貌进行了分析. 结果表明, 在脉冲频率和电流密度分别固定为5000Hz和20A/dm²时, 氧化膜主要含锐钛矿和金红石相TiO₂,随着处理时间的延长, 金红石TiO₂的相对含量逐渐增加; 氧化膜呈多孔结构, 表面布满了尺寸在300nm～1μm之间的TiO₂颗粒, 随着处理时间的延长, 这些颗粒微孔的尺寸明显变大, 其密度逐渐减小.     

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%.     

Electrochemical characteristics of nanotubes formed on Ti-Nb alloys

Titanium and Ti alloys have been used extensively as bone-implant materials due to their high strength-to-weight ratio, good biocompatibility and excellent corrosion resistance. In this work, we have investigated the effects of the β-stabilizing element Nb on the morphology of nanotubes formed on Ti-xNb alloys using 1.0 M H₃PO₄ electrolyte containing 0.8 wt.% NaF and various electrochemical methods. Oxide layers consisting of highly ordered nanotubes with a wide range of diameters (approximately 55-220 nm) and lengths (approximately 730 nm-2 μm) can be formed on alloys in the Ti-xNb system as a function of Nb content. The nanotubes formed on the Ti-Nb alloy surface were transformed from the anatase to rutile structure of titanium oxide. The titanium oxide nanotube surface was observed to have lower corrosion resistance in 0.9% NaCl solution compared to titanium oxides surfaces on Ti-xNb alloys without the nanotube morphology.     

Sodium fluoride-assisted modulation of anodized TiO₂ nanotube for dye-sensitized solar cells application

This work reports the use of sodium fluoride (in ethylene glycol electrolyte) as the replacement of hydrofluoric acid and ammonium fluoride to fabricate long and perpendicularly well-aligned TiO? nanotube (TNT) (up to 21 μm) using anodization. Anodizing duration, applied voltage and electrolyte composition influenced the geometry and surface morphologies of TNT. The growth mechanism of TNT is interpreted by analyzing the current transient profile and the total charge density generated during anodization. The system with low water content (2 wt %) yielded a membrane-like mesoporous TiO? film, whereas high anodizing voltage (70 V) resulted in the unstable film of TNT arrays. An optimized condition using 5 wt % water content and 60 V of anodizing voltage gave a stable array of nanotube with controllable length and pore diameter. Upon photoexcitation, TNTs synthesized under this condition exhibited a slower charge recombination rate as nanotube length increased. When made into cis-diisothiocyanato-bis(2,2?-bipyridyl-4,4?-dicarboxylato) ruthenium(II) bis (tetrabutyl-ammonium)(N719) dye-sensitized solar cells, good device efficiency at 3.33 % based on the optimized TNT arrays was achieved with longer electron time compared with most mesoporous TiO? films.     

Fabrication of Gradient TiO2 Nanotubes on Ti Foil by Anodization

A new anodization based method is developed to fabricate a gradient in TiO₂ nanotube diameters and lengths on Ti foil. In the method, the applied anodization voltage is increased step by step, while the Ti foil is immersed into an aqueous solution of hydrofluoric acid progressively during anodization. The gradient TiO₂ nanotubes with tube diameters ranging from 55 to 105 nm and lengths ranging from 300 to 500 nm across 12 mm of Ti foil are obtained. The formation mechanism of gradient diameter and length is also discussed. The gradient structure is potentially useful as new cell instructive materials (CIMs) for guided cell movement and culture, novel drug delivery vehicles, size‐selective biosensors, or other sensor applications.     

A titania nanotube-array room-temperature sensor for selective detection of hydrogen at low concentrations

A tremendous variation in electrical resistance, from the semiconductor to metallic range, has been observed in titania nanotube arrays at room temperature, approximately 25 degrees C, in the presence of < or = 1000 ppm hydrogen gas. The nanotube arrays are fabricated by anodizing titanium foil in an aqueous electrolyte solution containing hydrofluoric acid and acetic acid. Subsequently, the arrays are coated with a 10 nm layer of palladium by evaporation. Electrical contacts are made by sputtering a 2 mm diameter platinum disk atop the Pd-coated nanotube array. These sensors exhibit a resistance variation of the order of 10(4) in the presence of 100 ppm hydrogen at 25 degrees C. The sensors demonstrate complete reversibility, repeatability, high selectivity, negligible drift and wide dynamic range. The nanoscale geometry of the nanotubes, in particular the points of tube-to-tube contact, is believed to be responsible for the outstanding hydrogen gas sensitivities.     

Synthesis and Characterization of Niobium-doped TiO2 Nanotube Arrays by Anodization of Ti-20Nb Alloys

Well crystallized niobium-doped TiO₂ nanotube arrays（TiNbO-NT） were successfully synthesized via the anodization of titanium/niobium alloy sheets,followed with a heat treatment at 550 C for 2 h.Morphology analysis results demonstrated that both the titanium/niobium alloy microstructure and the dissolution strength of electrolyte played major roles in the formation of nanotube structure.A single-phase microstructure was more favorable to the formation of uniform nanotube arrays,while modulating the dissolution strength of electrolyte was required to obtain nanotube arrays from the alloys with multi-phase microstructures.X-ray diffraction（XRD） and X-ray photoelectron（XPS） analysis results clearly demonstrated that niobium dopants（Nb 5+） were successfully doped into TiO₂ anatase lattice by substituting Ti 4+ in this approach.