Effects of impurities containing phosphorus on the surface properties and catalytic activity of TiO2 nanotube arrays

TiO₂ nanotube arrays were prepared by titanium anodic oxidation with either HF or H₃PO₄/NH₄F aqueous electrolyte solutions. The samples were characterized by means of X-ray diffraction (XRD), infrared spectroscopy (IR), Raman spectroscope, photoluminescence spectra (PL) and photocurrent response. Aqueous solutions of methylene blue or Cr(VI) ions were used as the target pollutants to compare catalytic activities of the two nanotube array types. The amorphous impurities containing phosphorus were confirmed by XRD and IR, for the sample synthesized with H₃PO₄/NH₄F electrolytes. They closed a portion of the active sites, acted as recombination centers of photo-generated charges, and were also involved in the negative reactions of competing photo-generated holes or OH radicals. The TiO₂ nanotube arrays formed in the H₃PO₄/NH₄F electrolytes exhibited a stronger fluorescence spectrum, a weaker photocurrent and a lower catalytic activity than the sample fabricated with HF electrolyte without phosphorus impurities.     

Morphology, luminescence, and electrical resistance response to H2 and CO gas exposure of porous InP membranes prepared by electrochemistry in a neutral electrolyte

Porous InP membranes have been prepared by anodization of InP wafers with electron concentration of 1 × 10¹⁷ cm⁻³ and 1 × 10¹⁸ cm⁻³ in a neutral NaCl electrolyte. The internal surfaces of pores in some membranes were modified by electrochemical deposition of gold in a pulsed voltage regime. Photoluminescence and photosensitivity measurements indicate efficient light trapping and porous surface passivation. The photoluminescence and electrical resistivity of the membranes are sensitive to the adsorption of H₂ and CO gas molecules. These properties are also influenced by the deposition of Au nanoparticles inside the pores.     

Nanoporous alumina membrane prepared by nanoindentation and anodic oxidation

The fabrication of nanopatterned surfaces at large scale attracts the interest of research groups from a wide range of areas as biotechnology, nanoelectronics and nanomagnetism. An extended method to pattern the surface in the nanoscale is the fabrication of ordered arrays of nanoelements based on porous templates as Nanoporous Anodic Aluminium Oxide (NAAO). One of the challenges of the NAAO fabrication, based on self-organized methods, is the control of the symmetry and lattice parameter of the ordered nanoporous films. In this work, we present a combined method based on Atomic Force Microscopy (AFM) nanoimprint and anodic oxidation of Al surface. AFM nanoindentations substitute the first anodization process and even more important, allow us to control the symmetry and the lattice parameter of the ordered arrays. In addition, by using AFM nanoimprint method it is possible to select the region were the ordered alumina grows. We demonstrate that square nanoporous arrays of alumina with lattice parameter of 105 nm can be obtained by this method.     

溶液组分对铝阳极氧化多孔膜界面电性能的影响

采用电渗法研究了电解质溶液组分对铝阳极氧化多孔膜层界面电性能的影响。结果表明，多孔膜分别经含Ｆ＾－，ＰＯ＾３－４，ＳｉＯ＾２－３或单宁酸溶液浸泡处理后，膜在０．０１ｍｏｌ／ＬＫＣｌ溶液中等电点由原来的ｐＨＩＥＰ＝９．２０分别移至ｐＨＩＥＰ＝３．４０，４．３０，３．３０display structure     

Anodic characterization of mercury microelectrodes for determinations of anions in real samples

The anodization of mercury microelectrodes was investigated in synthetic samples containing several strong and weak electrolytes at different concentrations. In particular, the effects on mercury anodization due to the presence of NaOH, HClO₄, NaCl, NaI, NaF, Na₂SO₄, NaHCO₃, Na₂CO₃, tartaric and citric acids, were studied in solutions containing either each species or mixtures of them, and without addition of supporting electrolyte. Some of the electrode processes studied led to linear calibration plots e.g. 1 × 10⁻⁵ − 1 × 10⁻⁴M Cl⁻, 1 × 10⁻⁶ − 1 × 10⁻⁵M I⁻, 5 × 10⁻⁴ − 3 × 10⁻³M SO₄²⁻, 5 × 10⁻⁴ − 2 × 10⁻²M HCO₃⁻, with typical correlation coefficients of 0.998–0.999. The anodization of mercury microelectrodes was also investigated directly in wine, rain, tap and mineral water, without pretreatment and without addition of supporting electrolyte. In the real samples only the ions Cl⁻ and HCO₃⁻ could be quantified, and the values found were in agreement, within 3–5%, with the reference values obtained by using Italian standard methods for food.     

Effect of electrolysis conditions on photocatalytic activities of the anodized TiO2 films

Photocatalytic activities of anodized TiO₂ films for decomposition of gaseous acetaldehyde were investigated. The anodized TiO₂ films were fabricated by galvanostatic anodization in a mixed electrolyte composed of H₂SO₄, H₃PO₄, and H₂O₂. Pre-nitridation treatment effectively enhanced the photocatalytic activity of the anodized TiO₂ films. The electrolysis parameters such as anodization time, current density, electrolyte temperature, and electrolyte composition significantly affected the photocatalytic activity of the anodized TiO₂ films. The improvement of photocatalytic activity of the anodized films is attributed to increase in surface areas of the anodized specimens.     

马来酸在束状TiO2阳极氧化膜上的电催化还原

采用阳极氧化法在0.5 mol·L-1硫酸+1 mol·L-1马来酸的混合溶液中制得了束状TiO2薄膜.X射线衍射(XRD)分析表明样品的晶型结构主要为无定形态;所制得的样晶通过原子力显微镜(AFM)观察,束状结构TiO2的宽度约2-5μm,长度超过20μm,束状结构中包含的纳米棒直径约80-150 nm.将制得的束状TiO2膜电极在上述混合溶液中直接进行原位的循环伏安扫描和恒电流电解实验.研究结果表明,马来酸在该电极表面异相电催化还原生成丁二酸;在恒电流电解过程中采用电极原位活化可明显提高丁二酸的产率和电流效率,并指出改进电极的原位活化技术是未来研究工作的主要目标.     

A novel approach to large-scale formation of through-hole porous anodic aluminum template

A novel anodic oxidization equipment was designed to fabricate a large number of porous anodic alumina （PAA） templates in one time. This approach improved the efficiency of the preparation of the PAA templates remarkably in a normal lab and is expected to be used for the large-scale production in the future.     

阳极氧化/GCD新工艺法制备镍基超级电容器薄膜电极

采用磷酸阳极氧化法在金属镍表面形成阳极氧化复合膜,在1 mol·L^-1氢氧化钾溶液中进行大电流密度恒流充放电(GCD)处理, 使基体表面形成一层多孔纳米花瓣状膜. 采用扫描电镜(SEM), X射线光电子能谱(XPS), X射线衍射(XRD)仪, 对膜的形貌、组成和结构进行了表征, 使用电化学工作站、电池寿命测试仪对该膜的电容特性进行了测试. 结果表明, 所制氧化膜由三维多孔纳米花瓣状的NiO、α-Ni(OH)₂和β-Ni(OH)₂构成, 该膜具有优异的电容特性, 其在电流密度为6.7 A·g^-1时,比电容量达1509 F·g^-1, 而当电流密度为66.7 A·g^-1时,比电容量为1120 F·g^-1 (为6.7A·g^-1时的74%).在电流密度为66.7 A·g^-1时, 经过2000次循环测试后比电容量基本保持不变.     

Preparation of High-Orderly TiO2 Nanotubes in Organic Solution and Characterization of C-doped TiO2

"High-orderly TiO2 nanotube arrays were fabricated by anodic oxidation of pure titanium substrate in organic electrolyte containing fluoride. Different morphological nanotubes of titania were obtained through controlling the different anodization voltages and durations. The length of the longest nanotubes was approximately 60 1m and the length-to-width aspect ratio was about 600. The nanotube layers were then annealed at different temperatures (450, 550, and 650 oC) in air for 2 h. The samples were characterized by scanning electron microscopy, X-ray diffraction (XRD), energy dispersive X-Ray (EDS) and UV-Vis spectrometer. The XRD results demonstrated that the as-anodized samples were amorphous and the structure changed to antanse and rutile when the samples were annealed at higher temperature. The EDS microanalysis indicated the presence of carbon in the TiO2 nanotubes. The result of degradation of methylene blue showed clearly that the photocatalytic activity of C-doped TiO2 nanotubes increased by 10%."