二次阳极氧化制备TiO_2纳米管阵列及光催化性能研究

采用二次阳极氧化法制得高度有序的TiO2纳米管阵列,并与一次阳极氧化法制备TiO2纳米管的形貌和光催化活性进行了比较。利用FESEM和XRD表征分析纳米管阵列的形貌和结构。研究结果表明:二次阳极氧化法制备的TiO2纳米管阵列克服了一次阳极氧化法制备的TiO2纳米管的表面粗糙有絮状物、管长不均等缺陷,制备出表面平滑,长度均匀的TiO2纳米管阵列,相同条件下与一次阳极氧化制得的TiO2纳米管的光催化降解速率进行对比,前者比后者提高了近一倍。     

量子点敏化TiO_2纳米管的研究进展

总结近年来量子点敏化TiO2纳米管的制备方法。介绍了量子点敏化TiO2纳米管的原理及量子点的选择、TiO2纳米管的表面状态、量子点与TiO2纳米管的结合方式对光电及催化性能的影响。在此基础上,提出提高光电及催化性能的方法并指出值得关注的研究方向。     

TiO2纳米管阵列电催化降解甲基橙

采用阳极氧化法制备了TiO2纳米管阵列电极,通过考察其对模拟染料废水甲基橙(MO)的光催化降解效率来优化制备条件。研究了TiO2纳米管阵列电极电催化降解MO的活性及其影响因素,并考察了MO降解反应动力学。结果表明,MO溶液pH、电解槽压、支持电解质浓度等是TiO2纳米管阵列电极催化效率的重要影响因素。TiO2纳米管阵列电催化降解MO的反应遵守一级反应动力学规律,与TiO2纳米管阵列光催化降解MO的行为一致,且表观反应速率常数不随MO溶液浓度不同而发生改变。     

恒电流法制备Cu2O/TiO2复合纳米管阵列异质结光电极

通过在含F-离子的电解液中阳极氧化Ti薄片基底制备了TiO2纳米管阵列,随后通过恒电流沉积的方法在在TiO2纳米管阵列顶部原位电沉积了Cu2O纳米颗粒。场发射电子扫描显微镜显示TiO2纳米管这列被成功制备,通过恒电流电化学沉积后,TiO2纳米管阵列顶部出现大量纳米颗粒物质,并且随着沉积时间的延长,可以控制沉积物的量。通过X-射线衍射谱的特征衍射谱图我们可以发现TiO2锐钛矿的衍射峰以及相对较弱的Cu2O衍射峰,这说明Cu2O晶体的结晶度不高。在能谱（EDS）图中我们可以发现Ti、Cu、O三种元素,结合XRD以及FE-SEM结果我们可以指出,通过恒电流法确实可以在TiO2纳米管阵列顶部原位沉积Cu2O纳米颗粒。     

CdS/PbS量子点共敏化三维结构TiO_2纳米管阵列光电极的制备及其光电化学性能表征

通过阳极氧化法在钛丝网基底上制备出三维结构的TiO2纳米管阵列。采用连续离子层吸附与反应法制备了CdS、PbS、CdS/PbS量子点(QDs)敏化TiO2纳米管阵列光电极。利用X射线衍射仪、扫描电子显微镜、能谱定量分析、高分辨透射电镜、紫外–可见漫反射光谱对其形貌和结构进行了表征。结果表明:CdS、PbS量子点成功沉积在TiO2纳米管阵列上,QDs/TiO2纳米管阵列具有比纯TiO2纳米管阵列更好的可见光吸收性能。使用电化学工作站测试光电极材料的光电化学性能,结果表明:QDs/TiO2纳米管阵列具有良好的可见光响应性和稳定性;在100mW/cm2氙灯光照下,CdS/PbS/TiO2光电极具有最高的光电流密度,为5.86mA/cm2,分别是单一量子点敏化CdS/TiO2、PbS/TiO2光电极的3.35、1.21倍。对比在钛片基底上的二维结构TiO2纳米管阵列,三维结构纳米管阵列的光电流随入射光角度增大而衰减的缺点得到极大改善,这对其在太阳能电池中的实际应用有重要意义。     

TiO2纳米管阵列膜光催化降解苯胺

利用TiO2纳米管阵列光催化降解含苯胺水样,考察了影响苯胺降解率的各种因素。结果表明,在照射光源波长254 nm,反应时间120 min和苯胺水溶液pH=9时,TiO2纳米管阵列光催化氧化苯胺的效果最好,苯胺降解率达到87%;另外在苯胺水样中加入含Fe3+、Cu2+的金属盐和少量的H2O2氧化剂后,对TiO2纳米管阵列的催化活性具有促进作用,其苯胺降解率分别提高了42%、31%和19%。探讨了TiO2纳米管阵列光催化降解苯胺的反应机理。     

Pt纳米颗粒修饰TiO2纳米管阵列的合成及其光电化学性能

采用阳极氧化法在含0.4 mol/L HF的乙二醇电解液中制备高度有序的一维TiO2纳米管阵列,并采用柠檬酸溶剂热还原法在TiO2纳米管阵列表面沉积Pt纳米颗粒,研究Pt纳米颗粒对TiO2纳米管阵列光电化学性能的影响,对纳米管的结构、形貌、成分进行了表征,采用电化学工作站对沉积前后的TiO2纳米管阵列进行循环伏安扫描,并用5 W紫外LED灯对不同沉积条件下样品的光电流进行测试. 结果表明,所制TiO2纳米管排列整齐,管径均匀,约为150 nm,壁厚约20 nm,管长约为20 mm;尺寸约20 nm 的Pt纳米颗粒在纳米管内部分布均匀,Pt以单质形式存在. Pt沉积可提高TiO2纳米管的电化学活性,并明显增加TiO2纳米管对紫外光的吸收能力和光电流响应,Pt纳米颗粒的沉积温度为100℃时具有最大光电流响应,最高瞬时光电流值为289.84 mA.     

二氧化钛纳米管阵列制备和光催化降解甲基橙

采用电化学阳极氧化的方法,以氟化铵水溶液为电解液,在纯钛表面制备了TiO2纳米管阵列。以甲基橙为模拟污染物,考察了TiO2纳米管阵列光催化降解效果。结果表明,TiO2纳米管阵列催化降解效果要好于TiO2薄膜电极,60、120和180 min时,降解率分别为56%、88%和100%;而TiO2薄膜电极的降解率分别为43%、76%和91%。在此基础上,考察了阳极氧化电压、氧化时间和焙烧温度对阳极氧化过程的影响规律。结果表明,阳极氧化电压在10～25 V,氧化时间在1～2 h,焙烧温度在500℃时所制备的TiO2纳米管阵列光催化降解性能最好。     

TiO2纳米管的制备及表征

以锐钛矿型TiO2纳米晶和NaOH为原料,利用水热法制备了TiO2纳米管。采用X射线衍射(XRD)、透射电镜(TEM)、微孔分析仪等手段对所得样品的结构、形貌、组成进行了研究。并且研究了温度和NaOH的浓度对TiO2纳米管比表面积的影响。实验表明,所得产物为锐钛矿型TiO2纳米管,选择适当的水热处理温度及合适的NaOH浓度可以得到比表面积比较大的TiO2纳米管。     

水热法制备TiO2纳米管研究进展

近几年TiO2纳米管在光催化、太阳能电池、环境净化和传感器等方面引起了人们的广泛关注,然而有关水热法制备的TiO2纳米管的化学组成和形成的具体机理尚无定论。笔者综述了目前国内外有关水热法制备TiO2纳米管的组成和形成机理,为水热法制备结构可控的TiO2纳米管提供参考。     

Significantly enhanced structural and thermal stability of anodized anatase nanotube arrays induced by tensile strain

Anatase nanotube arrays were grown by anodization with high crystallinity and a well ordered nanotubular structure. Nanotubes were stable to 800 °C, and this enhanced thermal stability of anatase nanotube arrays (without Ti support) was related to the induced tensile strain/stress inside the nanotube wall. The anatase-to-rutile phase transformation of titania nanotube arrays induces a tensile stress inside the nanotube wall that increases the critical nucleation size of rutile phase, as opposed to a compressive stress usually occurred on the surface of titania thin films or nanoparticles.     

Fabrication,modification and environmental applications of TiO2 nanotube arrays (TNTAs) and nanoparticles

Among the semiconductors, titanium dioxide has been identified as an effective photocatalyst due to its abundance, low cost, stability, and superior electronic energy band structure. Highly ordered nanotube arrays of titania were produced by anodization and mild sonication. The band gap energy of the titania nanotube arrays was reduced to 2.6 eV by co-doping with Fe, C, N atoms using an electrolyte solution containing K₃Fe(CN)₆. The photoconversion of phenol in a batch photoreactor increased to more than 18% based on the initial concentration of phenol by using a composite nanomaterial consisting of titania nanotube arrays and Pt/ZIF-8 nanoparticles. A layer-by-layer assembly technique for the deposition of titania nanoparticles was developed to fabricate air filters for the degradation of trace amounts of toluene in the air and preparation of superhyrophobic surfaces for oil-water separation and anti-corrosion surfaces.     

Formation mechanism and packing options in tubular anodic titania films

Titania nanotube arrays were synthesized via anodic oxidation of titanium foils in glycerol electrolyte containing NH₄F at anodization voltage ranging from 10 V to 30 V. The structural parameters of self-organized periodic arrays of titania nanotubes were determined by small-angle neutron scattering and scanning electron microscopy techniques. Transmission electron microscopy and electron diffraction studies of single-standing nanotubes revealed the presence of nanocrystalline titanium oxide phases with oxidation states lower than +4 (TiO, Ti₂O₃). Several assumptions on growth and self-organization mechanism of nanotube arrays have been made.     

Photoelectrochemical properties of Fe-doped TiO2 nanotube arrays fabricated by anodization

Ti–Fe alloys with Fe contents of 0.05, 0.5 and 1.0 wt% were obtained using the arc-melting method. Fe-doped TiO₂ nanotube arrays were prepared by anodizing Ti–Fe alloys in ethylene glycol solution containing 0.25 wt% NH₄F and 10 wt% H₂O. The microstructure, crystal structure and photoelectrochemical properties of the nanotube arrays were characterized using scanning electron microscopy, X-ray diffraction, UV–Vis diffuse reflectance spectroscopy and electrochemical analyzer. Results show that doping of 0.05 wt% Fe improves the photoelectrochemical properties of titania nanotube arrays significantly, whilst further increasing the Fe contents to 0.5 and 1.0 wt% degrades these properties. The external potential has a considerable influence on the photocurrent density at doping content of 0.5 wt% Fe.     

Morphology and Microstructure of As-Synthesized Anodic TiO2 Nanotube Arrays

The as-grown structure of electrochemically synthesized titania nanotube arrays is investigated by scanning electron microscope (SEM) in combination with transmission electron microscope (TEM) as well as X-ray diffraction (XRD). The analysis reveals a preferred growth direction of the nanotubes relative to the substrate surface and the well control on the nanotube arrays morphology. The crystal structure of the anatase phase is detected and exists in the tube walls without any thermal treatment, which makes it possible to realize the application of as-formed TiO₂ nanotubes avoiding the degradation of the nanotube structures when sintering. In addition, a new growth, layered model of the anodic TiO₂ nanotubes is presented to obtain further understanding of the growth mechanism.     

Photoelectrocatalysis reactivity of independent titania nanotubes

Two types of independent titania nanotube arrays with the separated tube wall structure have been fabricated by a controlled anodization process and used for photoelectrocatalysis (PEC) applications. The photocatalysis degradation efficiency of the organic pollutant is improved from 6.0 to 9.2% through increasing tube length and inter-tube space. The PEC degradation efficiency is 20.4% at an applied potential of 2.885 V for titania long nanotube array. An electro-Fenton-assisted PEC reaction system has been developed using titania long nanotube array and an iron sheet as two anodes in a parallel connection and a multiporous carbon as one cathode. The current distribution among three functional electrodes is conducted to optimize titania PEC reaction and electro-Fenton reaction. Accordingly, the degradation efficiency is improved from 20.4% in PEC to 60.2% in electro-Fenton-assisted PEC, and the mineralization efficiency is also improved from 8.1 to 37.4%. The corresponding reaction rate constant of 5.19 × 10⁻³ min⁻¹ is even higher than that of 3.98 × 10⁻³ min⁻¹ for the sum of individual oxidation reactions of titania PEC, electro-Fenton, and anodic electrolysis.     

Hydroxyapatite coating on titanium surface with titania nanotube layer and its bond strength to substrate

A vertically aligned titania nanotube layer on titanium surface was prepared by electrochemical anodic oxidation in an F⁻-containing electrolyte, followed by annealing at 450 °C. Bioactive hydroxyapatite (HA) coatings on as anodized titania nanotube layer were obtained by a biomimetic method without other surface treatment. The morphology, crystal structure, and components of the titania nanotube layer and bioactive coatings were examined by scanning electron microscopy, thin film X-ray diffraction, and Fourier transform infrared spectroscopy. The bond strength between the HA coatings and substrates was tested using a mechanical tester. The diameter of the titania nanotubes was about 100 nm, the wall thickness about 19 nm and the height about 1 μm. HA rapidly deposited on the as anodized nanotube surface after immersion in a biomineral solution only for 1 day. The HA coatings were carbonated apatite and composed of a number of column-like crystals with nanometer size. Tensile test shows that the bond strength between the HA coating and the nanotube layer was larger than 15.3 MPa.     

TNAs的制备条件及可见光下GQDs/TNAs复合材料的性能初探

采用阳极氧化法制备了二氧化钛纳米管阵列（TNAs），探索了制备条件对TNAs表面形貌结构的影响；并采用电泳法制备了石墨烯量子点/二氧化钛纳米管阵列（GQDs/TNAs）复合材料，以罗丹明B为目标降解物，初步考察了复合材料的光催化性能；进而通过X射线衍射（XRD）、X射线光电子能谱（XPS）、拉曼光谱、紫外-可见漫反射（UV-vis DRS）、电化学阻抗（EIS）和光电压响应等手段对其结构和光电学特征进行了分析。结果表明，氧化次数和电解液类型对TNAs排列的有序性具有显著影响，二次氧化时间、二次阳极电压和NH₄F质量分数对TNAs的管长、管径具有明显影响；适宜条件下GQDs的掺杂有助于提升TNAs的光催化性能，经120min的可见光照射后，制备的GQDs/TNAs复合材料对罗丹明B的降解率达到70.3%，较TNAs提高了19.7%，且具有良好的稳定性；光电学测试同样表明该GQDs/TNAs复合材料的光吸收效率和光电子转移能力较TNAs有明显提高。     

Photoelectrocatalytic properties of Ag nanoparticles loaded TiO2 nanotube arrays prepared by pulse current deposition

A pulse current deposition technique was adopted to construct highly dispersed Ag nanoparticles on TiO₂ nanotube arrays which were prepared by the electrochemical anodization. The morphology, crystallinity, elemental composition, and UV-vis absorption of Ag/TiO₂ nanotube arrays were characterized by scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), and diffuse reflectance spectra (DRS). In particular, the photoelectrochemical properties and photoelectrocatalytic activity under UV light irradiation and the photocatalytic activity under visible light irradiation for newly synthesized Ag/TiO₂ nanotube arrays were investigated. The maximum incident photon to charge carrier efficiency (IPCE) value of Ag/TiO₂ nanotube arrays was 51%, much higher than that of pure TiO₂ nanotube arrays. Ag/TiO₂ nanotube arrays exhibited higher photocatalytic activities than the pure TiO₂ nanotube arrays under both UV and visible light irradiation. The photoelectrocatalytic activity of Ag/TiO₂ nanotube arrays under UV light irradiation was 1.6-fold enhancement compared with pure TiO₂ nanotube arrays. This approach can be used in synthesizing various metal-loaded nanotube arrays materials.     

TiO2纳米管阵列的研究进展

近年来TiO2纳米管阵列在光催化等领域展现出良好的应用前景,对其制备技术和应用研究已成为研究的热点。本文对TiO2纳米管阵列的制备方法作了综合介绍,概述了其研究现状及最新应用进展。