多孔钛表面TiO2纳米管的阳极氧化制备及光催化性能（英文）

对多孔钛表面制备TiO2纳米管的阳极氧化工艺进行研究。在两种电解质溶液中采用阳极氧化法分别对多孔钛和钛箔进行表面处理。一种电解质溶液是含有0.5%HF的冰醋酸,另一种电解质溶液是含有0.5%NH4F(质量分数)的乙二醇溶液(醇水体积比4:1)。结果表明:两种方法在钛箔上都可以生成TiO2纳米管,而多孔钛表面只能在NH4F电解质溶液中生成纳米管,HF溶液中过高的电流密度是纳米管在多孔钛基体上难以生成的主要原因。采用扫描电子显微镜和X射线衍射仪对不同基体上的TiO2纳米管进行表征,相比钛箔基体上的纳米管管壁,多孔钛上的纳米管管壁更薄。对所制备的TiO2热处理研究表明,锐钛矿相在400°C时形成,并在700°C完全转变为金红石相。经450°C热处理样品的光催化性能最好。光催化性能也受到多孔钛孔隙率的影响,在孔隙率为60%时光催化性能最好。     

Self-organized TiO2 nanotubes in mixed organic–inorganic electrolytes and their photoelectrochemical performance

The formation of self-organized TiO₂ nanotube array films by electrochemical anodizing titanium foils was investigated in a developed organic–inorganic mixed electrolyte. It was found that the structure and morphology of the TiO₂ nanotube layer were greatly dependent upon the electrolyte composition, anodizing potential and time. Under the optimized electrolyte composition and electrochemical conditions, a controllable, well-ordered TiO₂ nanotube array layer could be fabricated in a short time. The diameters of the as-prepared TiO₂ nanotubes could be adjusted from 20 to 150 nm, and the thickness could be adjusted from a few hundred nanometers to several micrometers. The photoresponse and the photocatalytic activity of the highly ordered TiO₂ nanotube array films were also examined. The nanotube array film with a thickness of about 2.5 μm had the highest incident photon to photocurrent conversion efficiency (IPCE) (34.3%) at the 350 nm wavelength, and had better charge transfer ability under UV light illumination. The photocatalytic experimental results indicated that the 450 °C annealing samples have the highest photodegradation efficiency for methyl orange pollutant.     

阳极氧化工艺条件对氮化钽烧结体电性能的影响

用纳米氮化钽粉末烧结制备了氮化钽烧结体,分析了烧结体的物相结构,研究了形成液种类、形成液浓度、温度、电流密度以及赋能电压等条件对氮化钽阳极氧化膜电性能的影响。结果表明,该烧结体是由纯氮化钽组成的,氮化钽阳极块体阳极氧化过程的最佳赋能工艺:磷酸溶液浓度0.01%,形成液温度55℃,电流密度40mA/g,形成电压小于16V。     

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。     

Construction of self‐organized free‐standing TiO2 nanotube arrays for effective disinfection of drinking water

BACKGROUND: In this study, the efficacy of disinfection surface water using anodic TiO₂ films was investigated. The as‐prepared photocatalyst demonstrated excellent photocatalytic disinfection of E. coli cells. Free‐standing and self‐organized TiO₂ nanotube arrays were synthesized via a facile electrochemical anodization method, prior to calcination. RESULTS: Over 95% of the initial 10⁶ cpu mL^?1 E. coli cells were inactivated within 50 min of UV‐A photocatalytic disinfection, despite the influence of various ionic species and organic compounds commonly present in groundwater. This was justified by the unique double‐walled nanotubular structure of the TiO₂ photocatalyst, which provided efficient delocalization of electron carriers and promoted anti‐recombination of photogenerated pairs of electrons and holes. Based on the experimental results obtained, cations enhanced the overall disinfection process while anions had an inhibitory effect on disinfection rates. CONCLUSION: The photocatalyst exhibited high efficiency in terms of photocatalytic disinfection of E. coli cells present in groundwater. It is deemed promising for applications in drinking water treatment owing to its superior disinfection performance, as well as high settleability, which promotes recovery and reuse of the catalyst. Copyright © 2010 Society of Chemical Industry     

Nanostructured gold films exhibiting almost complete absorption of light at visible wavelengths

Nanostructured metal surfaces have been known to exhibit properties that deviate from that of the bulk material. By simply modifying the texture of a metal surface, various unique optical properties can be observed. In this paper, we present a simple two step electrochemical process combining electrodeposition and anodization to generate black gold surfaces. This process is simple, versatile and up-scalable for the production of large surfaces. The black gold films have remarkable optical behavior as they absorb more than 93% of incident light over the entire visible spectrum and also exhibit no specular reflectance. A careful analysis by scanning electron microscopy reveals that these unique optical properties are due to their randomly rough surface, as they consist in a forest of dendritic microstructures with a nanoscale roughness. This new type of black films can be fabricated to a large variety of substrates, turning them to super absorbers with potential applications in photovoltaic solar cells or highly sensitive detectors and so on.

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硬质阳极氧化制备多孔疏水膜

采用硬质阳极氧化技术在铝合金表面制备了微米多孔多级复合结构氧化膜层,研究了多孔结构膜层疏水特性。通过电子显微镜和接触角测量仪分析发现,不同孔结构参数具有不同接触角疏水特性。当获得致密、更小尺度的多级微孔结构时,可以增加表面空气在三相界面中所占的比重,在不进行低能材料修饰情况下,使其表面静态水接触角增加,最大可达到130 o,该结果可以为阳极氧化工业应用提供一定实验参考。     

AC anodization of aluminum, electrodeposition of nickel and optical property examination

Commercial grade aluminum was anodized to form porous anodic films using alternating current at a voltage of 15 V and a temperature of 25°C. The AC anodization was implemented in phosphoric acid and in an electrolyte modified by dissolving 1.1 g/l iron powder. The presence of iron species in the modified electrolyte did not make iron to be incorporated in the film and appeared not to change the pore diameter, but doubled the film thickness. Electrodeposition of nickel was carried out to pigment the films. Pores of the films produced in the modified electrolyte were also found more accessible for nickel pigmentation. Reflectance spectrum of a nickel-pigmented film produced in the modified electrolyte was measured, and its solar absorptance and thermal emittance were calculated. It has been shown that AC anodization of aluminum in phosphoric acid modified by a small number of intentionally added species such as iron species, followed by electrodeposition of nickel, has potential in developing a method for cheaply preparing selective solar absorbing surface of nickel-pigmented anodic films of aluminum.     

Kinetics of titania nanotube formation by anodization of titanium films

We report the kinetics of titania nanotube length evolution during anodization of titanium films. Our results show that the nanotube length increase is thermally activated, and governed by voltage-dependent activation energy 0.6 eV ≤ E^eff ≤ 1.1 eV expressed by E^eff = E₀-αV_anod where α is a constant and E₀ = 1.6 eV is a voltage-independent term. The proximity of E₀ to that of oxygen diffusion in titania suggests that oxygen transport across the titania walls at the pore bottoms is the rate-limiting step. These results provide insights into the mechanism of titania nanotube formation and a framework for their rational synthesis for applications.     

氨基乙酸对镁-锂合金阳极氧化膜的影响

在镁-锂合金阳极氧化中以氨基乙酸为添加剂制取氧化膜,并讨论氨基乙酸对氧化膜结构、形貌及性能的影响.利用X射线衍射仪(XRD)、扫描电子显微镜(SEM)、无损涡流测厚仪、极化曲线(Tafel)和电化学交流阻抗谱(EIS)等分析了镁-锂合金基体和氧化膜的组成、表面形貌、厚度以及耐蚀性,并讨论其耐蚀机理.结果表明:阳极氧化膜主要由氧化镁、氢氧化镁和氢氧化锂构成;随着氨基乙酸的质量浓度的增加,阳极氧化膜趋于平整、致密,孔洞均匀;添加氨基乙酸形成的阳极氧化膜的自腐蚀电位正移,自腐蚀电流密度变小,当其质量浓度为6 g/L时,氧化膜耐蚀性最优,自腐蚀电流密度为1.12×10-7A/cm2;但当氨基乙酸的质量浓度过高时,氧化膜耐蚀性反而下降.电化学阻抗谱对氧化膜耐蚀性变化规律的分析与极化曲线结果相一致.