导电玻璃上室温沉积钛膜及TiO2纳米管阵列的制备与表征

在掺氟的SnO2(FTO)导电玻璃衬底上采用射频磁控溅射的方法室温沉积纯Ti薄膜,以NH4F/甘油为电解液,经电化学阳极氧化得到结构有序、微米级的TiO2纳米管阵列/FTO复合结构,并通过场发射扫描电子显微镜(FESEM)、X射线衍射(XRD)以及光电化学的方法对纳米管阵列进行了表征.研究表明,在氩气气压为0.5Pa,功率为150W,时间为0.5h条件下在导电玻璃上室温沉积获得钛膜的结构为晶带T型组织,表面均匀性好且致密度较高;在电压为30V下,随着阳极氧化时间从1h延长至3h,纳米管的管径从50nm增加到75nm,纳米管的长度从750nm增至1100nm后减至800nm,管壁由平滑变为波纹状;随氧化电压的升高,纳米管管径逐渐增大,而表面覆盖物逐渐减少,可通过在稀的HF溶液(0.05%(w,质量分数))中超声清洗去除;此外,瞬态光电流测试表明结晶的电极表现出更好的光电转换性能,紫外光照射下能促进TiO2光生载流子有效分离,在热处理温度为450℃时,具有较高的光电化学性能.     

透明TiO2纳米管/FTO电极制备及表征

采用射频磁控溅射方法在透明导电玻璃(FTO)上沉积纯钛薄膜, 室温条件下在H3PO4+HF电解液中通过恒压阳极氧化方法得到TiO2纳米管阵列, 并通过场发射扫描电子显微镜(FESEM)、X射线衍射(XRD)、UV-Vis透射光谱以及光电化学的方法对纳米管阵列进行了表征. 研究表明, 在电压为20 V、氧化时间为50 min时, 钛薄膜转化为TiO2纳米管阵列, 管长约为380 nm, 内径约为90 nm, 管壁约为15 nm; 再经过500 ℃空气热处理6 h之后得到锐钛矿型的TiO2纳米管/FTO透明电极, 在可见光区的平均透过率约为80%, TiO2禁带宽度为3.28 eV, 发生了蓝移, 带尾扩展到2.6 eV; 此外, 对结晶前后的复合电极分别在暗态和紫外光下进行线性扫描和瞬态光电流测试, 结果表明, 结晶的电极表现出更好的光电转换性能; 施加阳极电压和紫外光照射都能够促进TiO2光生载流子有效分离,使电子迅速传至导电玻璃表面通过外电路形成光电流.     

透明TiO2纳米管/FT0电极制备及表征

采用射频磁控溅射方法在透明导电玻璃(FTO)上沉积纯钛薄膜,室温条件下在H3PO4 HF电解液中通过恒压阳极氧化方法得到TiO2纳米管阵列,并通过场发射扫描电子显微镜(FESEM)、X射线衍射(XRD)、UV-Vis透射光谱以及光电化学的方法对纳米管阵列进行了表征.研究表明,在电压为20V、氧化时间为50min时,钛薄膜转化为TiO2纳米管阵列,管长约为380nm,内径约为90nm,管壁约为15nm;再经过500℃空气热处理6h之后得到锐钛矿型的TiO2纳米管/FTO透明电极,在可见光区的平均透过率约为80%,TiO2禁带宽度为3.28eV,发生了蓝移,带尾扩展到2.6eV;此外,对结晶前后的复合电极分别在暗态和紫外光下进行线性扫描和瞬态光电流测试,结果表明,结晶的电极表现出更好的光电转换性能;施加阳极电压和紫外光照射都能够促进TiO2光生载流子有效分离,使电子迅速传至导电玻璃表面通过外电路形成光电流.     

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.     

微含水量电解液中高管径比TiO_2纳米管阵列的制备

通过阳极氧化法在微含水量为0.5wt%的NH4F/乙二醇/H2O酸性电解质体系中制备了管径大、高管径比的二氧化钛(TiO2)纳米管阵列。采用SEM、XRD等测试手段对TiO2纳米管阵列形貌及晶相进行表征,探讨了不同氧化时间、电压对纳米管阵列形貌的影响,微含水量下氧化电压可以适当增加,更容易得到规整的长纳米管阵列;通过测定样品的光电流和紫外-可见光漫反射吸收光谱,研究分析了含水量以及超声工艺对纳米管光吸收及光电流特性,微含水量下得到的纳米管阵列可见光吸收边红移至420nm,对480~700nm可见光有明显的光吸收,光电流显著增大;丙酮作为超声介质可有效去除纳米管阵列表面的集束,能进一步提高纳米管阵列的光电性能。     

阳极氧化法制备二氧化钛纳米管阵列的研究

采用电化学阳极氧化法,将纯钛浸入HF酸水溶液,在钛基体表面原位构建高度有序的二氧化钛纳米管阵列,探讨阳极氧化电压、电解液浓度和电解液温度等对二氧化钛纳米管阵列尺寸和形貌的影响。通过SEM、XRD对二氧化钛纳米管阵列的结构特征进行表征,结果表明,不同的阳极氧化电压、电解液浓度和温度都将影响TiO2纳米管阵列的尺寸和形貌,在阳极氧化电压为20V,HF电解液浓度为0.5%t条件下,可制备出结构规整有序的TiO2纳米管阵列。     

ZnO/TiO2纳米管复合材料的制备及光电化学性能研究

采用电化学阳极氧化法制备TiO2纳米管,然后用光化学沉积法在TiO2纳米管表面沉积ZnO纳米颗粒制备ZnO/TiO2纳米复合材料。对样品进行了Raman谱、XRD和SEM表征,通过测定光电流-时间(I-t)和开路电压-时间(OCPT)曲线对ZnO/TiO2纳米复合材料的光电化学性能进行研究。结果表明,沉积ZnO没有改变TiO2的相结构;复合ZnO提高了TiO2的光电性能;在Zn(NO3)2浓度为10-3 mol.L-1的条件下制得的ZnO/TiO2纳米复合材料具有较好的光电性能。     

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.     

CuS/TiO2纳米管异质结阵列的制备及光电性能

利用水热反应制备了CuS/TiO2纳米管异质结阵列,采用场发射扫描电子显微镜(FESEM)、透射电子显微镜(TEM)和X射线衍射谱(XRD)等手段表征了异质结阵列的表面形貌和晶体结构.电流-电压曲线结果表明,CuS/TiO2纳米管异质结阵列具有明显的整流效应.根据表面光电压谱和相位谱,在376～600 nm之间,CuS/TiO2纳米管异质结阵列表现为p型半导体特征,电子在表面聚集;在300～376 nm之间表现为n型半导体特征,空穴在表面聚集;在376 nm处异质结阵列的表面光伏响应为零.CuS/TiO2和CuS/ITO之间界面电场的不同导致异质结在不同波长范围内表面电荷聚集的差异.光电化学性能测试发现,以CuS/TiO2纳米管异质结阵列为光阳极组成的光化学太阳电池,在大气质量AM 1.5G,100 mW/cm2标准光强作用下具有0.4%的光电转换能力.     

TiO_2纳米管阵列薄膜制备及生长机理的研究

本论文采用阳极氧化的方法,在NH4HF2+NH4H2PO4的混合水溶液中于室温下以金属钛为基体原位合成氧化钛纳米管阵列薄膜。讨论了电解液成分、外加电压、溶液的pH值对氧化钛纳米管阵列薄膜微观结构及形貌的影响,并建立了阳极氧化钛纳米管阵列薄膜的生长模型。氧化钛纳米管的结构与外加电压有很大的关系,只有电压在5～35V范围内才能制备出二氧化钛纳米管阵列薄膜,其管径随着电压的升高而增加,且管径范围为30～160nm。而薄膜的厚度与电解液有关,通过控制电解液的成分及pH值,可获得厚度为6.5μm的氧化钛纳米管阵列薄膜。     

Preparation and Characterization of TiO2 Nanotube Arrays via Anodization of Titanium Films Deposited on FTO Conducting Glass at Room Temperature

Self-organized TiO₂ nanotube arrays with micro-scale length were prepared on fluorine-doped tin oxide (FTO) conducting glass in NH₄F/glycerol electrolyte by electrochemical anodization of pure titanium films deposited by radio frequency magnetron sputtering (RFMS) at room temperature. The samples were characterized by means of field emission scanning electron microscopy (FESEM), X-ray diffraction (XRD), and photoelectrochemistry methods. The results showed that Ti films prepared at the condition of Ar pressure 0.5 Pa, power 150 W, and 0.5 h at room temperature possessed the zone T model structure with good homogeneity and high denseness. When the anodization time was prolonged from 1 to 3 h at the voltage of 30 V, the pore diameter of TiO₂ nanotubes increased from 50 to 75 nm, and the length increased from 750 to 1100 nm and then gradually decreased to 800 nm, while their wall morphology changed from smooth to rough. Also with increasing the anodization voltage, the pore diameter became larger, and the remaining oxide layer reduced, which could be easily removed by ultrasonic-chemical cleaning in 0.05% (w, mass fraction) diluted HF solution. Moreover, the photocurrent response curves and electrochemical impedance spectroscopy (EIS) results indicated that UV-illumination clearly enhanced the effective separation of the electron-hole pairs and the crystallized electrodes from the annealing treatment of as-anodized electrodes at 450 °C exhibited a better photoelectrochemical performance.     

Highly-ordered dye-sensitized TiO2 nanotube arrays film used for improving photoelectrochemical electrodes

Thin titanium oxide nanotube arrays (TNAs) films were synthesized by anodization of titanium foil in an aqueous dimethyl sulfoxide solution using a platinum foil counter electrode.TNAs up to 6.8 μm in length,120 nm in inner pore diameter,and 20 nm in wall thickness were obtained by 40 V potentials anodization for 24 h.Their microstructures and surface morphologies were characterized by XRD,TEM,SAED and UV-vis spectroscopy.The photoelectrochemical properties of as-prepared unsensitized and dye-sensitized TNAs electrodes were examined under simulated solar light (AM 1.5,100 mW/cm2) illumination.The results showed that the photocurrent of the dye-sensitized TNAs electrodes reached 6.9 mA/cm2,which was 6 times more than that of the dye-sensitized TiO2 nanoparticles (TNPs) electrodes.It implied that the electron transport process and the charge recombination suppression within TNAs electrodes were much more favorable in comparison with that in the TNPs electrodes.Electrodes applying such kind of titania nanotubes will have a potential to further enhance the efficiencies of TNAs-based dye-sensitized solar cells.     

钛丝原位组装固相微萃取涂层与高效液相色谱联用测定多环芳烃

利用恒电势法在钛丝表面原位阳极氧化组装固相微萃取(SPME)纤维,通过考察不同浓度电解质溶液和电解时间对二氧化钛纳米管(TiO₂NTs)形成及尺寸的影响来确定最佳的SPME纤维的形貌。 结果表明,NH₄F在水相中的质量分数为0.5%,乙二醇在水相中的体积分数为50%,氧化电势为20 V,温度为25 ℃,氧化时间30 min的条件下,得到内径为100 nm,壁厚为25 nm的有序纳米管排列。 利用组装得到的二氧化钛纳米管纤维涂层(TiO₂NTs/Ti)与高效液相色谱(HPLC)联用测定水样中的多环芳烃(PAHs)。 在优化的萃取条件下,该方法灵敏度高,线性范围宽,选择性和重复性好,操作简便。 利用此方法测量了实际水样中的PAHs浓度,得到了令人满意的分析结果。     

二氧化钛纳米管的制备与光催化活性

用阳极氧化法,室温条件下在含NH4F和H2O的电解液(丙三醇+NH4F+H2O;乙二醇+NH4F+H2O)中制备了TiO2纳米管阵列。用环境扫描电子显微镜(SEM)、X射线衍射仪(XRD)表征二氧化钛纳米管阵列的微观形貌和物相结构。在丙三醇电解液中,电压为60 V,65 V,70 V,75 V制备的纳米管直径依次为160、170、190、220 nm。对甲基橙(10 mg/L)降解测试TiO2纳米管阵列的光催化性能。研究结果表明:在100 V阳极电压制备经过500℃退火处理后的TiO2纳米管阵列的光催化效果最好,其光催化降解率在光照时间120 min时达到89.2%。     

Anodic growth of highly ordered TiO2 nanotube arrays to 134 microm in length

Described is the fabrication of self-aligned highly ordered TiO(2) nanotube arrays by potentiostatic anodization of Ti foil having lengths up to 134 mum, representing well over an order of magnitude increase in length thus far reported. We have achieved the very long nanotube arrays in fluoride ion containing baths in combination with a variety of nonaqueous organic polar electrolytes including dimethyl sulfoxide, formamide, ethylene glycol, and N-methylformamide. Depending on the anodization voltage, pore diameters of the resulting nanotube arrays range from 20 to 150 nm. Our longest nanotube arrays yield a roughness factor of 4750 and length-to-width (outer diameter) aspect ratio of approximately 835. The as-prepared nanotubes are amorphous but crystallize with annealing at elevated temperatures. In initial measurements, 45 mum long nanotube-array samples, 550 degrees C annealed, under UV illumination show a remarkable water photoelectrolysis photoconversion efficiency of 16.25%.     

The effects of conductivity and electrochemical doping on the reduction of methemoglobin immobilized in nanoparticulate TiO2 films

Methemoglobin (bovine) is immobilized from aqueous phosphate buffer (pH 5.5) solution into thin porous TiO(2) (anatase) films at ITO electrode surfaces. Films of TiO(2) are produced in a deposition process employing 40 nm diameter TiO(2) nanoparticles suspended in dry methanol followed by calcination. The pore size in these films is sufficient for methemoglobin (ca. 6 nm diameter) to diffuse into the porous structure (over several hours) and to remain immobilized in electrochemically active form. The electrochemical reduction of methemoglobin immobilized in TiO(2) and immersed in aqueous phosphate buffer at pH 5.5 is observed in two steps with (i) a small quasi-reversible voltammetric response at -0.16 V vs. SCE (Process 1) and (ii) an irreversible reduction peak at ca. -0.5 V vs. SCE (Process 2). The irreversible response is recovered only after slow chemical re-oxidation of hemoglobin to methemoglobin. At sufficiently negative applied potential "electrochemical doping" of the TiO(2) host is observed to lead to a considerably enhanced reduction Process 1. TiO(2) can be temporarily switched from a non-conducting (irreversible electron transfer) into a conducting (reversible electron transfer) state.     

利用钛保护层在ITO电极上直接制备大面积的超薄氧化铝膜

通过磁控溅射并引入钛保护层, 利用在0.3 mol·L^-1硫酸中20 V电压下二次阳极氧化, 在氧化铟锡(ITO)导电玻璃衬底上直接制备了超薄(约140 nm, 为阳极氧化前Al厚度的一半)、大面积(约4 cm²)的多孔阳极氧化铝(AAO). 扫描电子显微镜结果表明生成的微孔与衬底垂直, 孔径和孔间距分别约为30和60 nm. 我们发现钛保护层的作用是提高了Al层的附着性并且防止ITO被腐蚀, 在此体系中钛不能被其它的金属如铬、金、银或铜代替. 紫外-可见光谱透过率结果显示在阳极氧化过程中Ti被氧化成为透明的TiO₂, 利用10-20 nm的钛保护层以及二次阳极氧化过程, 能够保证高透明度. 在ITO上直接制备的这种透明、有序的AAO纳米结构在光子学、光伏领域和纳米制备等方面具有潜在应用.     

Investigation on the dynamics of electron transport and recombination in TiO2 nanotube/nanoparticle composite electrodes for dye-sensitized solar cells

In this work, we report on fabrication and characterization of dye-sensitized solar cells based on TiO(2) nanotube/nanoparticle (NT/NP) composite electrodes. TiO(2) nanotubes were prepared by anodization of Ti foil in an organic electrolyte. The nanotubes were chemically separated from the foil, ground and added to a TiO(2) nanoparticle paste, from which composite NT/NP electrodes were fabricated. In the composite TiO(2) films the nanotubes existed in bundles with a length of a few micrometres. By optimizing the amount of NT in the paste, dye-sensitized solar cells with an efficiency of 5.6% were obtained, a 10% improvement in comparison to solar cells with pure NP electrodes. By increasing the fraction of NT in the electrode the current density increased by 20% (from 11.1 to 13.3 mA cm(-2)), but the open circuit voltage decreased from 0.78 to 0.73 V. Electron transport, lifetime and extraction studies were performed to investigate this behavior. A higher fraction of NT in the paste led to more and deeper traps in the resulting composite electrodes. Nevertheless, faster electron transport under short-circuit conditions was found with increased NT content, but the electron lifetime was not improved. The electron diffusion length calculated for short-circuit conditions was increased 3-fold in composite electrodes with an optimized NT fraction. The charge collection efficiency was more than 90% over a wide range of light intensities, leading to improved solar cell performance.