染料敏化太阳电池用一维纳米结构氧化物光阳极薄膜的研究进展

染料敏化太阳能电池(DSC)由于其工艺简单、成本低廉、理论光电转换效率高,逐渐成为硅基太阳能电池的有力竞争者.DSC电池的光阳极主要起到对染料分子中激发出来的电子进行传导的作用,其光阳极薄膜大多数是由氧化物纳米晶制备的.氧化物纳米晶存在大量界面电阻,导致能量势垒,从而使染料分子中光生电子-空穴对不能有效分离,制约了DSC电池光电转换效率的提高.而高长径比的一维氧化物纳米光阳极薄膜有望降低界面电阻,促进电子-空穴对的有效分离,将是DSC电池光阳极材料开发的重要发展方向.详细论述了染料敏化太阳电池用一维纳米氧化物光阳极薄膜的研究进展.     

TiO2纳米结构在染料敏化太阳电池中的应用

利用纳米结构材料作为光阳极制备的染料敏化太阳电池被称为纳米结构染料敏化太阳电池(NDSSC).一般而言,它由纳米结构金属氧化物半导体的光阳极、染料敏化剂,电解质和对电极等几个部分组成.目前,纳米结构光阳极的研究主要集中在如何优化设计和成功制备各种纳米结构的光阳极材料,以改善NDSSC的光电转换性能.本文着重介绍了各种TiO2纳米结构,例如TiO2晶粒薄膜、TiO2准一维纳米结构、TiO2纳米复合物膜层、TiO2核-壳纳米结构、TiO2量子点敏化结构以及串联电池结构等在NDSSC中的应用,并评论了它们最近的主要研究进展.     

染料敏化太阳能电池光阳极TiO2薄膜的研究进展

在概述染料敏化太阳能电池工作原理基础上,着重分析电池光阳极TiO2薄膜的特性,并指出该薄膜在电池中所起的作用:负载染料、收集光生电子、分离电荷和传输光生电子;继而从表面修饰、离子掺杂、量子点敏化、制备复合薄膜、设计微观有序空间结构、设计核壳结构以及多手段共改性等方面对TiO2薄膜改性手段进行综述,并详细分析改性手段优化染料敏化太阳能电池性能的原因;最后,提出应把优化光阳极TiO2薄膜制备工艺及探讨薄膜接触面工作机理等作为今后的研究重点。     

微孔结构TiO2薄膜在准固态染料敏化太阳电池上的应用

采用200 nm聚苯乙烯(PS)造孔可以改善TiO2半导体薄膜的散射光性能,提高了准固态染料敏化太阳电池的光电性能。用10%聚苯乙烯造孔制备TiO2半导体组装的染料敏化太阳电池,在100 mW/cm2光强下电池光电转换效率达到2.94%,与不含造孔剂电池相比,光电转换效率提高52%。薄膜光学性能和入射单色光子–电子转化效率(IPCE)研究表明,电池光电性能的提高与薄膜的光散射改善和电池中染料的光捕获效率增大密切相关。     

加速采用直接写入电子束光刻

上海交通大学的张地与他在日本左贺大学的同事们发现：蝴蝶的翅膀有小型太阳光收集器的作用，这可启发科学家设计出更高效率的太阳电池。以自然界的蝴蝶翅膀为模板，张地等“复制”了一个太阳光收集器并将这一陷光结构转移到染料敏化太阳电池（DSC）上。DSC由间隙孔TiO2薄膜（孔隙中充满I／L3氧化还原电解液）和Pt或C的光阳极组成。     

不同染料吸附状态下染料敏化太阳能电池电化学阻抗谱研究

研究了TiO2表面染料的吸附状态不同时,染料敏化太阳能电池(DSC)的光电转换性能,并采用电化学交流阻抗技术(EIS)考察了不同染料吸附状态下DSC中的电子界面复合效应。结果表明,在非饱和吸附染料状态下,通过调整TiO2薄膜表面染料分子吸附量,可以降低界面电荷复合效应,使电子在TiO2薄膜中的传输过程中寿命增加,从而提高DSC的填充因子。     

不同染料吸附状态下染料敏化太阳能电池电化学阻抗谱研究

研究了TiO2表面染料的吸附状态不同时,染料敏化太阳能电池(DSC)的光电转换性能,并采用电化学交流阻抗技术(EIS)考察了不同染料吸附状态下DSC中的电子界面复合效应。结果表明,在非饱和吸附染料状态下,通过调整TiO2薄膜表面染料分子吸附量,可以降低界面电荷复合效应,使电子在TiO2薄膜的传输过程中寿命增加,从而提高DSC的填充因子。     

TiO2介孔薄膜电阻对染料敏化太阳能电池光电转换性能的影响

TiO2介孔薄膜的电阻可能是影响染料敏化太阳能电池光电转化效率的主要因素之一.设计了一种可用于测试TiO2介孔薄膜电阻的方法,研究了2种不同电阻值的TiO2介孔薄膜的电阻变化规律和2种TiO2介孔薄膜组装的染料敏化太阳能电池(DSC)的光电转换性能.结果显示,采用低电阻的TiO2薄膜光电极有利于DSC光电转换效率的提高.     

TiCl4处理提高染料敏化太阳能电池光电转换性能的研究

采用TiCl4对染料敏化纳米TiO2薄膜太阳能电池的光阳极基板和TiO2薄膜进行处理(以下简称为前处理和后处理),并将其组装成电池器件.主要研究了在70℃的条件下,TiCl4前处理和后处理对电池光电性能的影响.Ⅰ-Ⅴ曲线和扫描电镜结果显示,染料敏化纳米薄膜太阳电池基板经TiCl4处理后可以增大电池的开路电压;TiO2薄膜经过TiCl4处理后可以增大电池短路电流密度.经过前后处理的电池开路电压从670mV提高到703mV,短路电流密度从7.28mA/cm2提高到11.27mA/cm2,电池效率从3.71％提高到4.72％.     

柔性染料敏化太阳电池光阳极的优化及叠层电池的初步研究

在前期对冷等静压制备柔性染料敏化太阳电池(DSC)研究的基础上, 开展了浆料的优化及叠层DSC的研究。首先利用水热法处理由小颗粒P25调配的浆料, 发现处理后浆料的稳定性及DSC的效率得到了大幅提高。在P25浆料中加入不同比例200 nm TiO₂大颗粒提高光散射, 当P25与200 nm TiO₂比例为4:1时, DSC获得最高光电转换效率3.11%。在此基础上, 尝试用N719和N749双层染料敏化, 发现双层染料敏化后电池的效率介于N719和N749单独敏化的电池效率, 这可能是由于光阳极变厚不利于电子传输以及染料相互接触影响染料纯度, 光阳极厚度及电池结构有待于进一步优化。     

CNT-WO3元件的氨敏性能研究

以碳纳米管（CNT）为掺杂剂制成CNT—WO3旁热式气敏元件．采用混酸氧化法对碳纳米管进行纯化，化学沉淀法制备了纳米WO3微粉，并用TEM、FT—IR、TG—DSC、XRD等方法进行了表征．测试了元件在室温条件下对NH3的气敏性能．结果表明，碳纳米管掺杂元件在室温下对NH3的灵敏度远远高于纯WO3元件，其中0．8wt％的掺杂元件对NH3具有最高的灵敏度．另外，掺杂元件还具有检测浓度低、检测范围宽、选择性好等优点，是一种较为理想的氨敏元件．     

电介质TiO2粉体增强印刷碳纳米管薄膜的场发射性能

提出了一种可显著改善丝网印刷碳纳米管（CNTs）薄膜场发射特性的浆料制备方法。该方法以乙基纤维素为制浆剂,松油醇为溶剂,通过超声波把CNTs和TiO2粉体均匀地分散成CNTs/TiO2复合浆料,扫描电镜表明,丝网印刷的CNTs/TiO2薄膜在高温下烧结后形成连续的膜体,CNTs被球状的TiO2颗粒均匀隔离;场发射特性测试表明,与单纯的CNTs薄膜相比,CNTs/TiO2薄膜的开启电场降低了0.2V/μm,在电场强度为4.0V/μm时电流密度增加了26.5μA/cm2,结果说明,该方法对于提高CNTs的场发射特性有明显的作用,在CNTs发射显示器的制作中有很好的实际应用价值。     

Use of highly-ordered TiO(2) nanotube arrays in dye-sensitized solar cells

We describe the use of highly ordered transparent TiO(2) nanotube arrays in dye-sensitized solar cells (DSCs). Highly ordered nanotube arrays of 46-nm pore diameter, 17-nm wall thickness, and 360-nm length were grown perpendicular to a fluorine-doped tin oxide-coated glass substrate by anodic oxidation of a titanium thin film. After crystallization by an oxygen anneal, the nanotube arrays are treated with TiCl(4) to enhance the photogenerated current and then integrated into the DSC structure using a commercially available ruthenium-based dye. Although the negative electrode is only 360-nm-thick, under AM 1.5 illumination the generated photocurrent is 7.87 mA/cm(2), with a photocurrent efficiency of 2.9%. Voltage-decay measurements indicate that the highly ordered TiO(2) nanotube arrays, in comparison to nanoparticulate systems, have superior electron lifetimes and provide excellent pathways for electron percolation. Our results indicate that remarkable photoconversion efficiencies may be obtained, possibly to the ideal limit of approximately 31% for a single photosystem scheme, with an increase of the nanotube-array length to several micrometers.     

Recyclable and high-sensitivity electrochemical biosensing platform composed of carbon-doped TiO2 nanotube arrays

Electrode fouling and passivation are the main reasons for attenuated signals as well as reduced sensitivity and selectivity over time in electrochemical analysis. We report here a refreshable electrode composed of carbon-doped TiO(2) nanotube arrays (C-doped TiO(2)-NTAs), which not only has excellent electrochemical activity for simultaneous determination of 5-hydroxytryptamine and ascorbic acid but also can be easily photocatalytically refreshed to maintain the high selectivity and sensitivity. The C-doped TiO(2)-NTAs are fabricated by rapid annealing of as-anodized TiO(2)-NTAs in argon. The residual ethylene glycol absorbed on the nanotube wall acts as the carbon source and no foreign carbon precursor is thus needed. The morphology, structure, and composition the C-doped TiO(2)-NTAs are determined, and the corresponding doping mechanism is investigated by thermal analysis and in situ mass spectroscopy. Because of the high photocatalytic activity of the C-doped TiO(2)-NTAs electrode, the electrode surface can be readily regenerated by ultraviolet or visible light irradiation. This photoassisted regenerating technique does not damage the electrode microstructure while rendering high reproducibility and stability.     

Synthesis of carbon nanotube-TiO(2) nanotubular material for reversible hydrogen storage

A material consisting of multi-walled carbon nanotubes (MWCNTs) and larger titania (TiO(2)) nanotube arrays has been produced and found to be efficient for reversible hydrogen (H(2)) storage. The TiO(2) nanotube arrays (diameter ～60?nm and length ～2-3?μm) are grown on a Ti substrate, and?MWCNTs a few μm in length and ～30-60?nm in diameter are grown inside these TiO(2) nanotubes using chemical vapor deposition with cobalt as a catalyst. The resulting material has been used in H(2) storage experiments based on a volumetric method using the pressure, composition, and temperature relationship of the storage media. This material can store up to 2.5?wt% of H(2) at 77?K under 25?bar with more than 90% reversibility.     

流化床化学气相沉积法制备CNT/Fe-Ni/TiO2及其光催化性能研究

以Fe-Ni/TiO2为催化剂,采用流化床化学气相沉积法(FBCVD)在TiO2表面原位生长碳纳米管(CNT),得到CNT/Fe-Ni/TiO2复合光催化剂.通过SEM、XRD、UV-Vis等方法表征其结构和性能,以亚甲基蓝溶液降解为模型考察其光催化性能.结果表明:Fe-Ni/TiO2催化剂在FBCVD过程中,镍主要起到了CNT生长催化活性位的作用;在生长CNT后的复合光催化剂中,比例较低的Fe3+主要作为电子俘获剂,抑制TiO2光生电子空穴的复合;Ni和CNT共同起到将电子迅速地从TiO2中导出,从而降低光生电子空穴复合几率的作用.三者的协同作用显著改善了TiO2的光催化性能.其中Fe和Ni掺杂量分别为0.25mol%和4.75mol%样品的光催化活性较高,生长CNT后得到的复合光催化剂对亚甲基蓝的降解效率较纯TiO2提高约70%.     

低温制备介孔碳对电极构建的染料敏化太阳电池优化研究

以高比表面积的介孔碳为催化层材料通过低温烧结构建出对电极, 着重优化了其组装的染料敏化太阳电池(DSC)的整体结构和性能. 结果表明: 在碳浆料中添加Triton X100能改善碳颗粒之间以及碳催化层与衬底之间的接触界面, 促使DSC的转换效率从4.50%提升到4.82%, 增幅为7.1%. 随TiO₂薄膜厚度增加, DSC的转换效率先急剧增加, 随后趋于缓和, 其变化趋势是染料吸附量与电子传输路径相互竞争的结果. 在电解质中添加磷酸三丁酯能减小电解质电阻, 促使DSC的转换效率从3.59%提升到4.42%, 增幅为23.1%. 优化后, 介孔碳对电极DSC的转换效率达到4.82%.     

Photocatalytic decompositions of gaseous HCHO over Ag/TiO2 nanotube arrays

TiO2 nanotube arrays prepared by electrochemical anodization method attract considerable interest as a practical air purifier, as the nanotube arrays may form a TiO2 film with a porous surface and straight gas diffusion channel. Here, the TiO2 and Ag/TiO2 nanotube arrays with different Ag amount are used to degrade gaseous HCHO pollutants. The photocatalytic results confirm that the HCHO-degrading efficiency of the TiO2 nanotube arrays may vary with the amount of Ag nanoparticles, and the Ag amount within a certain range significantly improves the degradation rate of HCHO molecules. The main final product after HCHO degradation is detected to be CO2. Ag nanoparticles effectively act as electron trappers prohibiting the recombination of photo-excited electrons and holes, hence increasing the photocatalytic efficiency. However, excessive Ag nanoparticles form new recombination center of photo-excited electrons and holes to decrease the photocatalytic efficiency.     

CeO2修饰的透明TiO2纳米管电极的电致变色器件

采用电化学沉积法在阳极氧化制备的TiO2纳米管阵列管壁上沉积一层CeO2纳米颗粒,再将CeO2修饰的透明TiO2纳米管阵列薄膜对电极与聚三甲基噻吩变色电极组装成透过型电致变色器件.实验结果表明:CeO2修饰的TiO2纳米管阵列薄膜仍保持良好的光透过性,其电荷存储能力比纯TiO2纳米管电极提高了30%.经CeO2修饰的TiO2纳米管改善了器件的性能,与对电极为单一TiO2纳米管阵列的器件相比,其对比度仍保持在38%左右,其褪色时间由1.3 s缩短为0.8 s.电致变色器件快速响应得益于纳米管与纳米颗粒组成的复合结构的高比表面积和快速的电荷传输过程.     

Visible light photoelectrochemical performance of W-loaded TiO2 nanotube arrays: structural properties

Well aligned TiO2 nanotubes were successfully synthesized by anodization of Ti foil at 60 V in a fluorinated bath comprised of ethylene glycol with 5 wt% of NH4F and 5 wt% of H2O2. In order to enhance the visible light absorption and photoelectrochemical response of pure TiO2 nanotube arrays, a mixed oxide system (W-TiO2) was investigated. W-TiO2 nanotube arrays were prepared using radio-frequency (RF) sputtering to incorporate the W into the lattice of TiO2 nanotube arrays. The W atoms occupy the substitutional position within the vacancies of TiO2 nanotube arrays. The as-anodized TiO2 is amorphous in nature while the annealed TiO2 is anatase phase. The mixed oxide (W-TiO2) system in suitable TiO2 phase plays important roles in efficient electron transfers due to the reduction in electron-hole recombination. In this article, the effect of the sputtered W into the as-anodized/annealed TiO2 nanotube arrays on the photoelectrochemical response was presented.