TiO_2纳米管阵列的制备及其对316不锈钢光生阴极保护作用的研究

应用直接电化学阳极氧化法,于含氟电解液中,在纯钛表面制备一层整齐有序的TiO2纳米管阵列.扫描电子显微镜(SEM),X射线衍射(XRD)表征该纳米管阵列的形貌及晶体结构,光电化学联用系统研究其光电响应特性及对316L的光生阴极保护作用.结果表明:以TiO2纳米管阵列膜作为光生阳极时,在紫外光区(λ<387nm)有显著增强的光生电流响应,并对316不锈钢有较好的光生阴极保护作用.暗态下,光生电极电位仍可维持较长的一段时间,继续起到阴极保护作用.     

硫掺杂钛酸(盐)纳米管的表征与可见光光催化活性

以二硫化钛为钛源和硫源,通过与NaOH水热反应成功制备了硫掺杂钛酸(盐)纳米管。 采用X射线衍射、高分辨透射电子显微镜、扫描电子显微镜、扩展X射线吸收精细结构(EXAFS)和X光微区分析等手段对所制备的硫掺杂钛酸(盐)纳米管的结构、形貌、硫掺杂状态和掺杂量进行了表征,并以可见光光催化氧化乙醇反应为探针,采用原位气相色谱技术研究了硫掺杂钛酸纳米管的可见光光催化活性;结果表明,S原子以S2-形式取代了钛酸纳米管骨架中O原子的位置, 有效实现了硫掺杂;硫掺杂钛酸(盐)纳米管壁厚平均尺寸为2.9 nm,管径平均尺寸为9.7 nm。 可见光光催化氧化乙醇反应结果表明,掺硫钛酸纳米管在极低的掺硫量条件下,表现出比未掺杂的二氧化钛纳米管具有更高的可见光光催化活性。     

铁掺杂TiO2纳米管阵列对不锈钢的光生阴极保护

在含FeSO4的HF、H2SO4/HF、NaF/Na2SO4溶液中,通过电化学阳极氧化直接在纯钛表面制备Fe 掺杂的TiO2(Fe-TiO2)纳米管阵列. 应用X射线衍射(XRD)、扫描电子显微镜(SEM)、紫外-可见吸收光谱(UV-Vis)、X 射线光电子能谱(XPS)等手段对纳米管阵列的结构、形貌及化学组成进行表征. 利用光电化学测量研究Fe-TiO2纳米管阵列在不同波长范围内的光电响应特性和光生阴极保护行为. 考察了温度、时间、掺杂含量等参数对TiO2纳米管阵列的几何尺寸、形貌和光电性能的影响. 结果表明, Fe掺杂可有效减缓TiO2纳米管阵列载流子的复合, 窄化TiO2带隙宽度, Fe-TiO2在410-650 nm范围显示强吸收, 并使光谱响应扩展到波长大于400 nm 的可见光区. 实验结果还表明, Fe-TiO2纳米管阵列对316不锈钢(316L)具有良好的光生阴极保护作用, 暗态下阴极保护作用可继续维持.     

Nanotube formation from a sodium titanate powder via low-temperature acid treatment

Through structure-monitoring of nanotube formation from a lamellar sodium titanate, the present work explicitly elucidated the structure of the titanate nanotubes obtained from hydrothermal treatment of TiO(2) with NaOH. A new compound of an orthorhombic lepidocrocite-type sodium titanate was synthesized from calcination of a solid-state mixture of TiO(2) anatase and Na(2)CO(3) powders followed by hydrothermal treatment with NaOH. By treating with acid at 25 degrees C for Na(+) exchange with H(3)O(+), the titanate compound exfoliated and then proceeded with sheet-scrolling to form nanotubes, which had a structure and morphology very close to those of the nanotubes derived from NaOH treatment on TiO(2). During the low-temperature acid treatment, the lepidocrocite-type titanate is transformed from the orthorhombic C-base-centered symmetry to the body-centered symmetry. This transformation, accompanied by a size-contraction of TiO(6)-octahedron units, was critical for the formation of nanotubes. The present work provides direct evidence, for the first time, that the widely reported TiO(2)-derived titanate nanotubes can be obtained at low temperatures by scrolling the sheets exfoliated from the orthorhombic lepidocrocite-type titanate.     

Heterogeneous photocatalysis of methylene blue over titanate nanotubes: effect of adsorption

Titanate nanotubes were synthesized with hydrothermal reaction using TiO(2) and NaOH as the precursors and subsequent calcination at 400°C for 2h. The products were characterized with SEM and XRD. Adsorption and photocatalysis of methylene blue over titanate nanotubes and TiO(2) were investigated. The results indicated that titanate nanotubes exhibited a better photocatalytic degradation of methylene blue in a simultaneous adsorption and photodegradation system than that in equilibrium adsorption followed by a photodegradation system, whereas TiO(2) showed no significant differences in photocatalytic activity in the two systems. The methylene blue overall removal efficiency over TNTs in the first system even exceeded that over TiO(2). The different catalytic performances of titanate nanotubes in the two systems were tentatively attributed to different effects of adsorption of methylene blue, i.e., the promoting effect in the former and the inhibition effect in the latter. Decantation experiments showed that the titanate nanotube photocatalyst could be easily separated from the reaction medium by sedimentation. Thus titanate nanotubes with high sedimentation rates and concurrent adsorption represent a new catalyst system with a strong potential for commercial applications.     

阳极氧化法制备TiO_2纳米管阵列膜及其应用

由阳极氧化法制备的TiO2纳米管阵列,因其独特的有序结构而显示出优异的性能,在许多领域有着广泛的应用,成为一种很有发展前景的新型纳米结构材料。本文简要综述了制备TiO2纳米管阵列结构的方法及其应用研究进展。在比较了当前几种制备TiO2纳米管阵列方法的优缺点后,重点讨论了阳极氧化法制备TiO2纳米管阵列结构过程中,如何通过调整工艺参数来实现此类纳米管阵列结构的可控生长。最后评述了TiO2纳米管阵列材料研究的发展趋势和应用前景。     

TiO2-WO3 composite nanotubes by alloy anodization: growth and enhanced electrochromic properties

The present work demonstrates that uniform and highly ordered arrays of TiO(2)-WO(3) nanotubes can be grown by anodization of Ti alloys in an ethylene glycol/fluoride based electrolyte under selected electrochemical conditions. These aligned mixed oxide nanotube structures are highly suitable for enhanced electrochromic reactions; in particular we show that already small amounts of WO(3) (such as 0.2 at%) present in the tube oxide drastically improve the electrochromic properties (contrast, onset potential, cycling stability) of nanotube layer based devices.     

Hierarchically branched titania nanotubes with tailored diameters and branch numbers

Over the past decade, electrochemical anodization of self-organized TiO(2) nanotubes has been studied intensively with the main focus being on uniform diameters along the TiO(2) nanotube depth direction. In the present work, hierarchically branched TiO(2) nanotubes with tailored diameters and branch numbers are successfully achieved by adjusting the anodization voltage. Reducing the applied voltage by a factor of 1/√n causes a one trunk nanotube to diverge into n-branched TiO(2) nanotubes, whose diameters are 1/√n of the trunk nanotube diameter (n is an integer). Multiple layers of branched TiO(2) nanotubes are also obtained by further dividing the branched nanotubes when the applied voltage is further reduced step-by-step with a 1/√n factor. Enlargement and termination of TiO(2) nanotubes occur when the anodization voltage increases by √n times. Alternating increase and decrease in the applied voltage lead to a more sophisticated hierarchical structure of TiO(2) nanotubes. The fundamental understanding of these processes is discussed.     

氧化钛纳米管阵列制备及形成机理

采用电化学阳极氧化法在HF水溶液体系使纯钛表面形成一层结构规整有序的高密度TiO2纳米管阵列,考察了几种主要的实验参数（阳极氧化电压、温度、时间、电解液浓度）对TiO2纳米管阵列形貌和尺寸的影响.结果表明,阳极氧化电压是影响氧化钛形貌和纳米管尺寸的最主要因素,而温度和电解液浓度只影响TiO2纳米管阵列形成的时间.对TiO2纳米管阵列进行X射线衍射（XRD）和扫描电子显微镜（SEM）的分析,初步表征了TiO2纳米管阵列的电学性质.并讨论了TiO2纳米管的形成机理.     

规则结构钛酸盐自组装聚集体的制备

在水热条件下, 采用不同的钛源, 通过控制溶液碱度和冷却温度等反应条件, 利用无模板自组装技术, 在钛酸盐薄膜表面及溶液相中制备了鸟巢状和绒球状钛酸盐纳米带自组装聚集体以及海胆状钛酸盐纳米管自组装聚集体. 通过引入碳酸钠模板, 制备出形貌新颖的钛酸钠-碳酸钠香蒲状自组装聚集体复合材料. 初步研究了纳米自组装聚集体的形成机理, 认为其形成经历了一维纳米结构(纳米带或纳米管)的生长和一维纳米结构的自组装2个过程.     

暴露{001}面TiO2纳米片分等级花状结构的制备及其光催化活性

以钛酸盐纳米管为前驱体,在HF-H2O-C2H5OH的混合溶液中,采用一种简单的醇热方法合成了具有87%暴露{001}面的TiO2纳米片自组装形成的分等级花状TiO2超结构.运用X射线衍射、扫描电镜、透射电镜和N2吸附-脱附等方法对样品进行了表征,并在紫外光照射下于空气和溶液中分别考察了其光催化降解丙酮和甲基橙反应活性...     

SiW12、PbS对提高TiO2纳米管光电转换效率的协同效应研究

复合薄膜可以改善TiO2纳米管在光电转换时电子-空穴易复合和吸收光谱范围窄的缺陷。用电沉积法将多酸H4SiW12O40（SiW12）沉积在TiO2纳米管表面形成SiW12/TiO2纳米管复合薄膜,再用连续离子层吸附反应法（SILAR）将PbS吸附到SiW12 /TiO2纳米管复合薄膜表面,形成PbS/ SiW12/TiO2纳米管复合薄膜,所得薄膜的光电转换效率相较于TiO2纳米管提高了57倍。X射线衍射（XRD）和扫描电子显微镜（SEM）表征结果表明,用电沉积法和连续离子层吸附反应法实现了PbS/SiW12/TiO2纳米管复合薄膜的制备;紫外可见（UV-vis）吸收光谱测试表明,复合薄膜的光吸收带边扩展到了可见光区域,电化学阻抗测试（EIS）表明,复合薄膜具有更高的电子转移速率;荧光光谱（PL）测试表明,复合薄膜拥有更小的电子-空穴复合率。以上结果说明,SiW12、PbS与TiO2纳米管复合,很好地抑制了TiO2纳米管电子-空穴的复合,并拓宽了吸收光谱范围,能显著地提高TiO2纳米管的光电性能。本文探索了一种有效提高TiO2纳米管光电转换效率的方法,对TiO2纳米管复合薄膜的制备具有一定的参考意义。     

甘油-DMSO-H2O中阳极氧化TiO2纳米管阵列的生长与性能

采用NH4F-甘油-DMSO(二甲基亚砜)-H2O溶液体系的电化学阳极氧化法, 在金属钛基板上形成厚度为0.4-1.5 μm的有序TiO2纳米管阵列薄膜. 利用场发射电子扫描显微镜(FESEM)技术, 研究了电解液的组成及阳极氧化电压对TiO2纳米管阵列生长形貌的影响. 结果表明, 阳极氧化电压可以影响TiO2纳米管的径向尺寸和长度；通过改变电解液中DMSO/H2O的体积比, 能够调控纳米管的生成速率与形貌. 利用X射线衍射(XRD)对经过不同温度热处理的TiO2纳米管阵列薄膜的物相进行了分析. TiO2纳米管阵列薄膜的光电催化分解水过程的电压-电流特性测量显示, 光电流密度大于0.2 mA·cm-2.     

溶胶-凝胶模板法制备钛酸钡纳米管

采用氢氧化钡和钛酸四丁酯为前驱体, 溶胶-凝胶结合模板法制备了钛酸钡纳米管, 通过SEM, TEM, XPS和XRD等表征分析, 钛酸钡纳米管直径100 nm, 钛酸钡为立方相结构, 晶胞参数a＝3.995 Å.     

Hydrothermal synthesis of single-crystalline anatase TiO2 nanorods with nanotubes as the precursor

Preparation of anatase TiO2 nanorods from solutions in the absence of surfactants or templates has rarely been reported. The present work has found that hydrothermal treatment of titanate nanotube suspensions under an acidic environment resulted in the formation of single-crystalline anatase nanorods with a specific crystal-elongation direction. The nanotube suspensions were prepared by treatment of TiO2 in NaOH, followed by mixing with HNO3 to different pH values. The crystal size of the anatase nanoparticles obtained from the hydrothermal treatment increased with the pH of the suspensions, and nanorods with an aspect ratio up to 6 and a long axis along the anatase [001] were obtained at a pH slightly less than 7. A mechanism for the tube-to-rod transformation has been proposed on the basis of the crystalline structures of the tubes and rods. The local shrinkage of the tube walls to form anatase crystallites and the subsequent oriented attachment of the crystallites have been suggested to be the key steps involved in the nanorod formation.     

二氧化钛纳米管储氢能力的分子动力学研究

二氧化钛纳米管是一种有前景的储氢材料,因此,在本文中通过卷曲锐钛矿单分子层,获得锯齿型(Zig-zag)和手性型(Chiral)二氧化钛纳米管结构。并采用分子动力学方法(Molecular dynamics)研究了氢分子分别在锯齿型和手性型二氧化钛纳米管和碳纳米管中的分布情况,并计算其储氢能力。结果表明,与碳纳米管一样,锯齿型和手性型二氧化钛纳米管存在管间储氢和管内储氢情况,并且氢分子在管间和管内的分布与二氧化钛纳米管内、外两侧的氧原子相关。Lennard-Jones势能模型表明:氢分子向纳米管内部和管间隙处的低能处聚集,形成氢分子环结构。储氢量计算结果表明,虽然锯齿型和手性型二氧化钛纳米管储存的氢分子数目较多,但由于系统重量较大,储氢量较低,低于美国能源部6%的商业标准,不能满足实际需要,而碳纳米管储氢量接近这一标准。     

Synergistic effects of CdS in sodium titanate based nanostructures for hydrogen evolution

Synergistic effect of CdS decorated sodium titanate nanostructures showed enhanced H₂ production abilities. The confinement effect and synergistic effect of decorated CdS inside the sodium titanate nanotubes are investigated.     

NH4F/H3PO4体系中阳极氧化法制备TiO2纳米管阵列

以价廉的Ni板代替常用的Pt片为阴极,纯钛为阳极,采用电化学阳极氧化法在NH4F-H3PO4体系中制备出TiO2纳米管阵列.详细研究了制备参数(溶液酸度、氟离子浓度、外加电压和氧化时间)对所获纳米管阵列形貌的影响.采用场发射扫描电镜(FE-SEM)和X射线衍射(XRD)对样品的形貌和晶相结构进行了表征.在最优化的条件下,可以获得形貌规整、表面干净、有序的TiO2纳米管阵列.纳米管阵列的平均管径为60 nm.管长约530 nm.采用阳极氧化法制备的纳米管阵列是非晶态的.经400℃热处理2 h后,可以转变为锐钛矿相.实验结果还发现,经过热处理后,纳米管阵列变得更为有序,管径扩大至约95 nm.     

脉冲电沉积法制备Pt-TiO2 纳米管电极及其电催化性能

采用阳极氧化法在高纯钛片上原位组装TiO2纳米管阵列, 然后用脉冲电沉积方法将Pt沉积到TiO2纳米管阵列上, 制备出Pt-TiO2纳米管电极. 利用XRD和SEM对所获电极的微观结构和形貌进行表征, 结果表明, Pt纳米颗粒以花簇状分散在TiO2纳米管上, 晶粒大小约为25.6 nm. 对甲醇的电催化性能的研究结果表明, 脉冲电沉积制得的Pt-TiO2纳米管电极比TiO2纳米管电极和纯Pt片电极具有更高的电催化活性, 是Pt电极的40多倍.     

TiO2纳米管阳极氧化制备机理及热处理对其影响

采用阳极氧化方法,在NH4F+H2O的乙二醇溶液体系下制备了TiO2纳米管列阵薄膜,建立了TiO2纳米管列阵薄膜的"电场诱导"生长模型。TiO2纳米管的管形结构形成与TiO2的半导体性质相关。纳米管表面吸附的纳米粒子与管壁间空间有关系。经过退火处理的纳米管管口由12~14个直径为25~35 nm的纳米颗粒团聚体组成,600℃时,纳米管结构已被破坏。经过300~600℃之间不同温度处理后的TiO2纳米管呈现锐钛矿晶态,比表面积随温度升高呈下降趋势。