TiO2纳米管制备与掺杂改性的研究进展

本文总结近年来TiO2纳米管制备与掺杂改性的研究进展.介绍TiO2纳米管的制备方法以及纳米管的形成机理,讨论影响阳极氧化法制备TiO2纳米管的主要因素.总结使用不同元素对TiO2纳米管进行掺杂的方法以及效果,重点介绍N掺杂的不同方法以及提高TiO2纳米管性能的机理.介绍通过量子点和有机染料对TiO2纳米管进行表面改性的...     

二氧化钛纳米管的制备及其应用进展

结合TiO2纳米管良好的光电、催化、气敏等多种特性以及在光催化、太阳能电池、气体传感器等领域广阔的应用前景,综述了TiO2纳米管的制备方法和应用现状,提出了TiO2纳米管研究过程中存在的问题以及今后可能的发展趋势。     

非金属元素掺杂二氧化钦纳米管的研究进展

TiO2纳米管对大部分可见光不能进行有效地吸收利用,成为其实际应用的瓶颈.非金属元素掺杂TiO2纳米管可以有效地减小TiO2带隙,拓展光谱响应范围.本文介绍了非金属掺杂TiO2纳米管的原理和制备方法,对非金属单一元素掺杂、非金属与其它元素共掺杂TiO2纳米管的研究现状进行了详细的评述,指出了非金属掺杂TiO2:纳米管过程中存在的问题和未来的研究方向.     

二氧化钛纳米管制备方法及其应用研究进展

讨论了水热合成法和阳极氧化法2种二氧化钛纳米管制备方法,并比较了该2种方法制备的纳米管的区别。针对纳米管特点,对其在光催化、储能、氢敏材料、太阳能染料电池等领域的研究及潜在应用进行了综述,最后对二氧化钛纳米管研究方向提出了建议。     

TiO_2纳米管的制备和掺杂改性研究进展

二氧化钛纳米管由于其新奇的光电、催化、气敏等性能引起了广泛的关注,在太阳能电池、光催化、环境净化、气体传感器等领域有潜在的应用价值。文章概述了近年来在二氧化钛纳米管制备方法,掺杂改性及应用方面的进展,并讨论了今后可能的研究方向。     

稀土掺杂纳米二氧化钛光催化剂的研究进展

纳米二氧化钛(TiO_2)催化剂由于其高效、价廉、无毒、稳定等优点,被认为是一种极具应用前景的环境友好型光催化材料,它在空气净化、环境治理、光解水制氢、废水处理等环保领域得到了广泛的研究和应用。在对TiO_2改性研究中发现,稀土金属掺杂是较为有效和经济的手段,稀土离子的掺入不仅可以提高对有机污染物吸附量,还可以延迟锐钛矿相向金红石相的转变,增强TiO_2的光催化性能。目前,有关稀土掺杂TiO_2的综合性报道较少。本文简单介绍了稀土掺杂纳米TiO_2提高其光催化性能的机理,从单一稀土元素掺杂、稀土元素与其他元素共掺杂、稀土元素与稀土元素共掺杂纳米TiO_2光催化剂3个方面阐述了稀土掺杂纳米TiO_2光催化剂的研究进展,并在最后指出了稀土掺杂纳米TiO_2中存在的问题和未来的研究方向。     

掺杂型纳米二氧化钛光催化剂的制备

本文概述了掺杂纳米二氧化钛的方法及其制备方法。纳米二氧化钛作为一种光催化材料,在净化污水和保护环境方面被认为是最有潜力的一种材料。而通过对二氧化钛纳米颗粒进行掺杂改性可以提高纳米二氧化钛的光催化性能,使其满足现代生活中各种不同的需求。     

氮掺杂TiO_2纳米管/高岭土复合光催化剂的制备及光催化性能

以P25纳米TiO2为原料、尿素为氮源,通过水热法合成氮掺杂TiO2纳米管;同时以高岭土为载体,采用浸渍法制备氮掺杂TiO2纳米管/高岭土复合光催化剂。采用X射线粉末衍射、Fourier变换红外光谱、紫外-可见光谱和透射电子显微镜等表征样品的结构与形貌,并以甲基橙为模型化合物研究复合材料的光催化性能。结果表明：制备了锐...     

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。     

微波加热法制备TiO2/膨润土复合光催化材料

提出了一种制备TiO₂/膨润土复合光催化材料的新方法-微波加热法，并通过改变微波加热功率、微波加热时间、焙烧温度和焙烧时间等得到最佳制备条件。在模拟染料废水中，对催化材料的光催化性能进行了研究，结果发现微波加热法制备的复合光催化材料具有同常规法相当的光催化降解性能。     

Freestanding vertically oriented single-walled carbon nanotubes synthesized using microwave plasma-enhanced CVD

Freestanding single-walled carbon nanotubes (SWCNTs) have been synthesized in a vertical direction, perpendicular to the growth substrate, using applied DC substrate bias in a microwave plasma-enhanced chemical vapor deposition (PECVD) synthesis process. The degree of alignment and spatial density of SWCNTs demonstrate a strong dependence on the magnitude of applied bias, with increased alignment and decreased density with increased bias. The unique synthesis environment created by the application of a negative substrate bias in PECVD aligns SWCNTs along electric field lines and decreases SWCNT density due to bombardment by positively charged hydrogen ions. Multi-excitation wavelength Raman spectroscopy reveals shifts in dominant RBM peaks with the application of dc bias. Use of this technique to orient SWCNTs in the vertical direction may allow for three-dimensional SWCNT-based device architectures.     

微波法合成Cu-MCM-41介孔分子筛的研究

以硅酸钠、氯化铜等无机盐为原料,十六烷基三甲基溴化铵(CTAB)为模板剂,通过微波辐射方法合成不同铜含量的Cu-MCM-41介孔分子筛。分别采用X射线粉末衍射(XRD)、透射电子显微镜(TEM)和N2吸附-脱附等技术对产物的晶相、结构、形貌、比表面积和孔径分布进行表征。结果表明,通过微波辐射方法成功地合成出含有不同孔径的Cu-MCM-41介孔分子筛。随着原料配比中n(CuO)∶n(S iO2)(摩尔比)的增加,介孔分子筛的比表面积和孔体积变小,介孔有序性变差。     

The electrical conduction mechanism of multiwalled carbon nanotubes film synthesized by microwave plasma chemical vapor deposition

Multiwalled carbon nanotubes (MWNTs) were synthesized by microwave plasma chemical vapor deposition (MPCVD) on Ti/Si substrate with Ni catalyst. Then MWNT films were annealed at 300 °C for 10 min. Micro-Raman spectroscopy was performed to analyze the micro structure of the samples. It was noted from the Raman spectra that the ratio of I_D/I_G decreased after the annealing process, indicating more MWNTs were transformed to graphite structure at the temperature of 300 °C. In this research, the electrical properties of MWNTs film were investigated before and after the annealing process, different from the past research that focused on single or bundle of MWNTs. It was found that the I–V traces of the unannealed MWNTs film exhibited abrupt current increase and decrease phenomena by sweeping up and down voltages, respectively, and with different traces. Moreover, the threshold voltages for the saturation region increased after some successive measurements during sweeping up, but the similar effect was not observed during sweeping down. Similar phenomena were observed for the annealed MWNTs film; however, the threshold voltages, compared to that of the unannealed MWNTs film, spread out more during sweeping up and became smaller during sweeping down. It suggests that the nanotubes have thermally activated defects in rectifying conduction contacts between tungsten probes and MWNTs at the higher temperature induced by high applied voltages. Therefore, the breakdown voltages of the rectified contacts would change due to various thermally activated defects at higher temperatures. The equivalent circuit for the W-probe/MWNT-films/W-probe structure will be further presented in this study.     

微波固相法合成苯并恶嗪及其共混树脂的性能

邻位二烷基取代苯胺与苯酚和多聚甲醛经100 W微波辐照20 min反应得到了5种苯并恶嗪单体,将其中邻位为甲基和乙基取代的苯胺型苯并恶嗪与双酚A型苯并恶嗪(BAF)共混,采用红外光谱(FT-IR)、核磁共振氢谱(1H-NMR)、示差扫描量热仪(DSC)、动态机械分析(DMA)、热失重分析仪(TGA)、粘度仪和介电阻抗仪研究了共混树脂的粘温性、热性能及介电性能。结果表明,邻二甲基苯胺型苯并恶嗪(2m6m-BZ)与BAF以物质的量比3∶7共混的体系100～250℃下粘度<500 mPa.s,其固化后热性能接近固化后的纯BAF树脂,且介电常数<3.9,介电损耗低于0.003 5,优于其它共混树脂。     

Structural characterization and electrochemical performance of lithium trivanadate synthesized by microwave sol-gel method

The Li_1+xV₃O₈ material was successfully synthesized at 450 °C in short sintering duration by microwave sol-gel route. X-ray diffraction suggests oxygen defects in the lattice. Based on Randles-Sevcik formula, cyclic voltammograms measurements were conducted to measure Li⁺ ion diffusion coefficient. The material exhibits high discharge capacity of 250 mA g⁻¹ at 0.2 mA/cm² after 30 cycles in the range of 2.0-4.0 V. Alternating current impedance tests show that the growth of the charge transfer resistance at 0.4 mA/cm² is more rapid than that of at 0.2 mA/cm² as the galvanostatical charge-discharge continues.     

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.     

Lanthanum-doped PZT synthesized by the oxidant peroxide method and sintered by conventional and microwave routes

Lanthanum-doped lead zirconate titanate (Pb_0.95La_0.05Zr_1−xTi_xO₃) with two different compositions, x=0.20 (PLZT20) and 0.80 (PLZT80), were successfully obtained by the oxidant peroxide method (OPM). This environmental friendly synthetic route showed to be very attractive to prepare lead based ferroelectric powders since no carbon or halides compounds were used. Tetragonal perovskite structure was observed for PLZT80 and rhombohedral perovskite for PLZT20, with single phase identified in the powders calcined at temperatures higher than 700 °C. Powders crystallized at 700 °C were used to produce ceramic samples that were sintered at 1000 °C for 2 h by conventional and microwaves techniques. The composition of the fractured surface of ceramics were quite close to the nominal molar composition, indicating that the OPM promotes the formation of materials with high compositional homogeneity and similar microstructures regardless the sintering method used.     

Photocatalytic study of polymorphic titania synthesized by ambient condition sol process

Nanocrystalline titania of different phases were produced by ambient condition sol process with phase control originating from alterations in experimental variables. The produced titania photocatalysts were characterized by use of x-ray diffraction, BET surface area, transmission electron microscopy and related to methyl orange degradation. The results showed that the photocatalytic activity of brookite and anatase phase titania samples to be greater than that of Degussa P-25 and rutile phase titania sample. In addition, brookite, due to surface area considerations, appears to be the most photocatalytically active phase of titania.