不同制备条件对二氧化钛纳米管阵列及其结构的影响

采用阳极氧化法以NH4F/乙二醇为电解液制备高度有序的TiO2纳米管,研究了不同电解液浓度、电解电压、电解时间等参数对TiO2纳米管的影响.在不同温度下对TiO2纳米管进行退火处理.分别利用转靶X射线衍射仪(XRD)和场发射扫描电子显微镜(SEM)对TiO2纳米管阵列的物相结构和形貌变化进行表征.结合氧化过程电流密度变...     

阳极氧化法制备TiO2纳米管阵列

采用阳极氧化法在乙二醇体系电解液中制备TiO2纳米管阵列,获得了长度为15~20μm的底端纳米管与顶端纳米线的新型复合结构。讨论了电解液中不同含水量对该复合结构形成的影响,并采用两步阳极氧化法对该结构的形成机理进行了分析。结果表明,当乙二醇体系电解液含有0.4%(质量分数)NH4F和2%(体积分数)H2O时,电解液腐蚀速度适中,纳米管上端部分被选择性腐蚀,最终形成纳米管与纳米线的复合结构。     

三电极体系制备TiO2纳米管

利用电化学阳极氧化法在乙二醇和氟化铵溶液三电极体系中阳极氧化纯钛箔,制备出具有双面结构的TiO2阵列纳米管。研究了不同电压和电解液含水量对纳米管形貌的影响,通过扫描电子显微镜(SEM)和X射线衍射仪(XRD)分析了TiO2纳米管阵列的微观形貌及物相。     

高度有序TiO2纳米管的制备

采用电化学阳极氧化法制备高度有序的TiO2纳米管.通过控制不同的阳极氧化电压及电解液,得到形貌不同的TiO2纳米管.最长的TiO2纳米管达60μm,长径比为600.采用SEM对样品进行了表征.     

阳极氧化TiO2纳米管阵列的制备及场发射性能

采用阳极氧化法以HF水溶液为电解液制备二氧化钛(TiO2)纳米管阵列,用场致发射扫描电子显微镜和X射线光电子能谱对纳米管阵列的表面形貌、断面结构及元素组成进行表征,并使用场发射测试系统测试其场发射性能,研究了HF水溶液的pH值对TiO2纳米管阵列形貌(管径及管长)的影响。结果表明:调节电解液的pH值可改变TiO2纳米管阵列的形貌,从而提高其场发射性能。当电解液pH值为2.0时TiO2纳米管阵列的场发射开启场强降为2.52 V/μm,且具有较好的电流稳定性。     

TiO_2纳米管的制备及光电性能研究

以NH4F-乙二醇为电解液阳极氧化制备Ti基TiO2纳米管,利用扫描电镜(SEM)图像分析TiO2纳米管阵列的退火前后的形貌结构变化,研究退火温度对TiO2纳米管光电性能的影响。分别用CdS、曙红对TiO2纳米管进行敏化,并研究了其敏化后的光电性能和电极稳定性。结果表明:退火并未改变TiO2纳米管结构,经CdS敏化后的TiO2纳米管光电性能最好,且电极稳定性也较好。     

阳极氧化工艺参数对TiO_2纳米管形貌和性能的影响

采用阳极氧化法制备TiO2纳米管阵列,研究电解液成分、阳极氧化电压、阳极氧化时间、电解液温度及氧化次数对纳米管阵列微观结构及形貌的影响,探讨了TiO2纳米管阵列生长机理,并采用SEM、表面粗糙度仪、接触角测量仪对所得TiO2纳米管阵列的形貌、粗糙度、亲水性及表面能进行了表征和分析。结果表明,阳极氧化后Ti表面活性增加,相比于其他阳极氧化工艺参数,电解液成分对样品表面粗糙度、接触角及表面能的影响更大。     

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.     

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。     

大管径TiO_2纳米管的制备及其光解水性能研究

采用阳极氧化法制备小管径(20~300 nm)的TiO2纳米管已经有很多报道,但大管径的TiO2纳米管的制备还是一个挑战。为制备大管径的TiO2纳米管,研究了高水含量的电解液对纳米管管径的影响。结果表明,纳米管的管径随水含量的增加而增加(8%~12%(体积分数)),而水含量增加到13%(体积分数)时,无法得到规则的纳米管,进一步增加水含量到20%(体积分数),只能得到致密的TiO2薄膜。此外,在含有0.3%(质量分数)NH4F和12%(体积分数)H2O的乙二醇电解液中,研究了不同氧化电压对纳米管管径的影响。结果表明,在170 V氧化电压下制备的TiO2纳米管的管径可达到600 nm。纳米管的光解水性能测试结果表明,管径的增大有利于提高TiO2纳米管的光解水性能。     

Electrochemical fabrication of titania nanotube arrays with tunning nature of dimethyl sulfoxide and its application for hydrogen sensing

In the present work, tuning effects of dimethyl sulphoxide (DMSO) on the length, wall thickness, dimension and morphology of titania nanotube arrays fabricated by anodization was investigated. DMSO presented in both ethylene glycol and glycerol electrolytes provided excellent tunability in length, wall thickness and diameter of the produced TiO2 nanotube arrays by systematically varying the DMSO concentration. At the DMSO concentration of 12 wt% in ethylene glycol, the nanotube length could be up to 13.0 microm at 20 V for 8 h anodization. The TiO2 nanotube arrays produced in DMSO containing ethylene glycol or glycerol electrolytes displayed a high sensitivity to hydrogen at room temperature compared to the absence of DMSO. The further enhancement of resistance response could be achieved by coating a Pt and Pd layer on the surface of TiO2 nanotube-arrays. The presented work provided a simple way to control formation of TiO2 nanotube arrays through the tuning effects of DMSO in ethylene glycol or glycerol electrolytes.     

热处理工艺对TiO2纳米管阵列结构及其光电性能的影响

通过阳极氧化法在钛箔上制备了TiO2纳米管阵列,在不同热处理工艺下使其晶化.利用扫描电子显微镜(SEM)和X射线衍射(XRD)对TiO2纳米管阵列的形貌和结构进行了表征.结果表明,阳极氧化法制备的TiO2纳米管经450~750℃热处理后为纳米晶结构,平均晶粒尺寸随退火温度升高而增大,相同温度下氮气气氛中热处理的TiO2平均晶粒尺寸小于空气气氛中热处理的TiO2.氮气气氛下退火可拓宽TiO2由锐钛矿型(Anatase)向金红石型(Rutile)结构转变的热处理温度范围,650℃以上退火处理后,TiO2纳米管中掺杂有少量的氮.光照开路电位测试和稳态极化曲线测试结果表明,在氮气气氛中、经650℃退火处理2 h制备的TiO2纳米管阵列电极光电响应性能最佳,此时TiO2为锐钛矿型和金红石型的混晶结构.     

TiO_2纳米管半导体特性与光电催化动力学研究

通过阳极氧化法在有机溶液中制备TiO2纳米管阵列,随着氧化时间的不同,TiO2纳米管阵列呈现各异的形貌。通过光电流测试,考察了不同氧化时间和施加不同电压下的Ti/TiO2纳米管阵列光电极的光电化学响应,阳极氧化6h表面规整纳米管阵列并施加偏压0.1V光电流响应最强。通过测试Mott-Schott-ky曲线,计算不同氧化时间的TiO2纳米管阵列的半导体载流子浓度、平带电位、空间电荷层宽度和能带弯曲量等特征参数,理论上提出了TiO2纳米管阵列生长机理。在光电催化降解无机氨氮的实验中,所得到的电化学阻抗谱(EIS)表明,外加偏压0.1V时,TiO2纳米管阵列电极的光电催化活性最强,同时通过拟合电路分析可知,光电催化降低了电极界面的反应阻抗,加速了光生载流子的转移,在TiO2纳米管阵列电极/溶液界面Helmholtz层中发生的氧化还原反应是整个光电催化反应的速率控制步骤。     

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.     

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.     

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%.     

Front-side illuminated CdS/CdSe quantum dots co-sensitized solar cells based on TiO₂ nanotube arrays

We fabricated a front-side illuminated CdS/CdSe quantum dots co-sensitized solar cell based on TiO(2) nanotube arrays. The freestanding TiO(2) nanotube arrays were first detached from anodic oxidized Ti foils and then transferred to the fluorine-doped tin oxide to form photoanodes. An opaque Cu(2)S with high electrochemical activity was used as the counter electrode. A photovoltaic conversion efficiency as high as 3.01% under one sun illumination has been achieved after optimizing the deposition time of CdSe quantum dots and the length of the TiO(2) nanotube arrays. It is observed that the power conversion efficiency of quantum dots sensitized solar cells from the front-side illumination mode (3.01%) is much higher than that of the back-side illumination mode (1.32%) owing to the poor catalytic activity of Pt to polysulfide electrolytes and light absorption by the electrolytes for the latter.     

氧化钛纳米管阵列阳极氧化法的制备及形成机理研究

采用阳极氧化法在氢氟酸、冰醋酸、聚乙二醇水溶液恒压处理钛箔,制备了结构规整有序的高密度TiO2纳米管阵列.利用电子扫描电镜(SEM)对纳米管的形貌进行了表征,详细考察了氧化时间对纳米管阵列形貌和尺寸的影响,绘制并分析了电流-时间曲线.对纳米管阵列的形成机理进行了研究,认为纳米管的形成经历了4个关键阶段,分别是致密膜的生成、微孔的出现、纳米管的融合和管长稳定生长至最长.     

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。