【作者】 冯辉；

【导师】 蔡青云；

【作者基本信息】 湖南大学 ， 分析化学， 2014， 博士

【摘要】 能源和环境是人类在21世纪所面临的两大问题,半导体光催化材料在解决环境污染和能源短缺方面有着巨大的应用前景。利用太阳能进行光催化一直是人们研究的热点,光催化技术由于其价格便宜,环境友好,稳定性高等优点,在环境污染控制领域具有广泛的应用前景。半导体光催化是近年来国内外最活跃的研究领域之一,尤其是随着纳米技术的飞速发展,光催化纳米材料通过吸收太阳光,可以直接分解环境污染物,无二次污染,所以深入研究纳米半导体光催化剂对于从根本上解决环境污染问题具有重大的意义。纳米TiO₂作为纳米材料的一员,具有优异的光催化活性和光电特性。自1972年Fujishima发现了在TiO₂电极上光分解水制氢的作用以来,人们对TiO₂的光催化特性进行了大量的研究,其在光电转换、污染物降解、自洁净、传感器以及潜在的癌症治疗等高新技术领域显示出广阔的应用前景。TiO₂纳米管阵列具有表面形貌均一、比表面积大、孔径长度可调、高度取向、以及独特的电学、光学特性,自2001年被首次阳极氧化法制备以来,引起极大的研究兴趣。已有研究表明TiO₂纳米管阵列材料在光催化及传感领域具有广泛的应用前景。然而由于二氧化钛的禁带宽度较大（锐钛型及金红石型二氧化钛的禁带宽度分别为3.2eV和3.0eV）,只能吸收紫外光,而紫外光仅占太阳光的5%左右,相反可见光则占太阳光能量的约46%,对太阳能的利用率低。因此使二氧化钛对可见光产生响应从而提高二氧化钛半导体材料的太阳光利用效率是目前的研究热点。另外TiO2半导体材料导电率低,不能有效传递光生载流子,使得光生电子容易与光生空穴复合,降低了其光电转化效率。本论文针对以上问题开展研究,以有机污染物的去除及快速筛查为目标,以提高二氧化钛纳米管阵列的光/电催化活性为研究重点,通过对TiO₂纳米管阵列材料进行修饰和改良,以提高对太阳光的利用率和光电转化效率,及在有机污染物去除和生物传感领域的应用研究。具体研究内容如下：（1） CdTe/TiO2纳米管的制备表征和光催化的研究：采用脉冲电沉积技术,将与太阳光能带匹配的窄带半导体CdTe纳米颗粒修饰到TiO₂纳米管阵列中,由于CdTe的能带Eg-1.5eV,与太阳光能量最佳匹配,是合适的窄禁带半导体,能有效吸收可见光。应用该材料对有毒的有机污染物对硝基苯酚（PNP）在可见光照射下进行了光催化降解研究。以对硝基苯酚为目标物,探讨了CdTe/TiO2纳米管阵列电极的光催化氧化性能和影响PNP光催化降解效率的因素。结果表明影响PNP光催化降解效率的两个主要因素为目标物的初始浓度和溶液的pH值,其优化条件分别为：10mg/L,pH～3。在氙灯照射下2个小时内,35毫升10mg/LPNP的去除率几乎100%（第2章）。（2） CdTe/Au-TiO2光电免疫传感检测持久性有机污染物三（2,3--二溴丙基）异氰脲酸酯（TBC）：采用简单的脉冲电沉积方法,将CdTe和Au纳米粒子同时共沉积到Ti02纳米管阵列上,构建了光电性能良好的CdTe/Au-TiO2光电传感电极。因为贵金属Au的工作函比Ti02半导体的工作函高,光生电子从Ti02迁移到邻近金属纳米颗粒上,导致在每个金属纳米颗粒与Ti02纳米管接触面区域形成肖特基势垒。肖特基势垒起到了有效的“电子陷阱”作用,避免了光生电子与空穴的复合,从而提高电极材料的光电催化活性。同时贵金属材料优良的导电性能有利于电子传导。以CdTe/Au-TiO2纳米管阵列为基底所构建的无标记光电化学免疫传感器,对持久性有机污染物三（2,3-二溴丙基）异氰脲酸酯（TBC）表现超灵敏,高选择性响应,对5.0×10-11～5.0×10-5M范围内的TBC浓度有线性响应,检测下限为50pM。并应用于湘江水样和浏阳河中水样TBC的定量检测（第3章）。（3）通过化学修饰方法使单分散的二氧化硅凝胶纳米粒子作为表面纳米印记结构的印记模板分子的支撑体,构建一种基于分子印迹聚合物的纳米粒子荧光光传感器。该传感器对持久性有机污染物全氟辛烷磺酸钠（PFOS）表现超灵敏,高选择性响应,对5.57～48.54ug L-1（10.36nM～90.2nM）浓度范围内的PFOS有线性响应,检测下限为5.57ug L-1（10.36nM,第4章）。更多还原

【Abstract】 Energy and the environment are two major problems which the human must face in the21st century. Semiconductor photocatalytic materials has huge application prospect in solving environmental pollution and energy shortage. Light catalysis by using solar energy has been research hot spot. Photocatalytic technology has extensive application prospect in the field of environmental pollution control because of its cheapness, environmental friendliness and high stability, etc. Semiconductor photocatalysis is one of the most active area of research at home and abroad in recent years. Especially with the rapid development of nanotechnology, photocatalytic nanomaterials can decompose environmental pollutants directly by absorbing sunlight, and no secondary pollution. So further study of nano semiconductor photocatalyst is of great significance to solve fundamentally the problem of environmental pollution.TiO2has its excellent photocatalytic activity and photoelectric properties as a member of the nanometer materials. Since1972, Fujishima found hydrogen production from water by photodecomposition in the TiO2electrode, a lot of research on the TiO2photocatalytic properties has been conducted, and it shows a broad application prospect in the photoelectric conversion, pollutants degradation, self clean, sensors and potential high-tech fields such as cancer treatment.TiO2nanotube arrays was prepared by anodic oxidation for the first time since2001, it gives rise to a lot of research interest because of its uniform surface morphology、large specific surface area、adjustable aperture length、high orientation、and the unique electrical and optical properties. Existing research shows that TiO2nanotube arrays has wide application prospection in the field of photocatalysis and sensing. However, due to the large forbidden band width of titanium dioxide(anatase and rutile type titanium dioxide forbidden band width are3.2eV and3.0eV, respectively.), it can only absorb ultraviolet light which accounts for only about5%of the sunlight. In contrast, the visible light accounts for about46%of sunlight energy, hence, the utilization of solar energy is very low. So make TiO2respond to visible light, and thus improve the utilization efficiency of sunlight of TiO2semiconductor materials is a hot spot in the present study. Furthermore, the conductivity of TiO2semiconductor material is low, and can’t transfer photo-generated carriers effectively which make it easier for the photo-generated electron and hole to recombine, and consequently reduce the photoelectric conversion efficiency.This thesis has carried out research aiming at the above problems, with the removal of organic pollutant andrapid screening for the target, and improving optical/electrical catalytic activity of the titanium dioxide nanotubes array as the research focus.The material of TiO2nanotube arrays were modified and improvedin order to improve the utilization ratio and the photoelectric conversion efficiency of sunlight, and application research in the field of organic pollutant removal and biological sensing. The concrete research content is as follows:(1) The preparation, characterization and the study about photocatalysis of the CdTe/TiO2nanotubes:By using pulse electrodeposit technology, the narrow band gap semiconductor CdTe nanoparticles have been modified into TiO2nanotube arrays. Because the band gap (Eg) of CdTe is about1.5eV which matchs well with sunlight energy, it can absorb effectively visible light. The photocatalytically oxidative decomposition of P-Nitrophenol (PNP) with the CdTe nanoparticles-modified TiO2nanotube arrays (CdTe/TiO2NTAs) as catalyst was investigated under visible light (400nm<λ<800nm)irradiation. The CdTe/TiO2NTAs show much higher degradation rate (0.0312min-1) than the unmodified TiO2NTAs (0.0071min-1). The enhanced photocatalytic activity is attributed to the extended absorption in the visible light resulting from the narrow-band-gap semiconductor CdTe and the effective separation of photogenerated carriers.The two main impact factors on PNP photocatalytic degradation efficiency are the initial concentration of the target and the pH value of the solution. The optimum conditions were as follows respectively:10mg/L and pH～3. Under xenon lamp irradiation within2hours,35ml of10mg/L PNP removal rate is almost100%(Chapter2).(2) CdTe/Au-TiO2NTAs was used for photoelectric immune sensing detection of persistent organic pollutants(pops):In this paper, Tris(2,3-dibromopropyl) isocyanurate (TBC) is for the first time as far as we know determined by ultrasensitive photoelectrochemical(PEC) immunoassay using an antibody-modified ternary hybrid CdTe/Au-TiO2nanotube arrays (NTAs) photoelectrode developed by pulse electrodeposition technique. The as-prepared hybrid shows enhanced photon absorption and photocurrent response, which subsequently increased photoelectrical conversion efficiency in the visible region. TBC-antibody (Ab) was developed in rabbits as a result of immunization with BSA-TBC conjugate and covalently cross- linked onto the CdTe/Au-TiO2NT As. Since the photocurrent is highly dependent on the TiO2surface properties, the specific interaction between TBC and the antibody results in a sensitive change in the photocurrent, which displayed a linear range of5.0×10-11-5.0×10-5M and a low detection limit of5.0×10-11M for TBC determination. This proposed strategy highlights the application of TiO2nanotube in visible-light-activated photoelectrochemical biosensing, which could largely reduce the destructive effect of UV light on biomolecules(Chapter3).(3) A perfluorooctane sulfonate (PFOS, C8F17SO3-) molecularly imprinted (MIP) fluorescence sensor was developed by anchoring the MIP polymer on the surface of SiO2NPs via a surface molecular imprinting process. Fluorescence dye and organic amine were covalently immobilized onto the surface of MIP-SiO2NPs to form a hybrid monolayer of dye fluorophores and amine ligands which acted as the receptor sites to bind PFOS(C8F17SO3-) species through the acid-base pairing and hydrogen-bond interaction under acid condition (pH～3.5). The specific binding of PFOS into the recognition cavities in the polymer matrixes results in the fluorescence quenching due to the electron transfer from the fluorescence dye to PFOS. This proposed method can selectively and sensitively detect down to5.57ug L-1of PFOS in water, and a linear relationship has been obtained covering the concentration range of5.57～48.54ug L-1(10.36nM～90.2nM)(Chapter4).更多还原