C2H4的微波场助气相光催化氧化

用溶胶-凝胶法制备了多孔性TiO     

具有高活性宽光谱响应的新型光催化材料

以二氧化钛为代表的传统光催化材料只能利用短波长的紫外光,太阳光利用率和量子效率低,其广泛应用受到极大限制．针对这一问题,近年来我们开展了一系列具有高活性和（或）宽光谱响应（包括紫外及可见光）的新型纳米光催化材料的研究．本文简要总结了相应工作的进展,并对可能影响光催化材料的活性和光谱响应的相关因素进行了探讨．     

TiO2光催化剂的光谱研究

采用sol-gel法制备了纳米TiO2光催化剂,运用FTIR,FT－Ranam,DSR等光谱技术对催化剂进行了表征,以光催化解油酸作为模型反应考察光催化活性。实验结果表明,催化剂的烧结温度对催化剂的晶相结构、半导体能带结构、光吸收性能及光催化活性均产生显著的影响,当烧结温度为400℃时,TiO2光催化剂具有最好的表观吸光度,最大的吸收带边,以及最佳的光催化活性。     

TiO2胶粒在铝合金表面的电泳沉积及所制薄膜的光催化性能研究

TiO₂ membranes were prepared on aluminum-alloy thin plates by electrophoretic deposition and dip coating in a colloid solution of TiO₂, respectively. The photocatalytic activity of TiO₂ membrane was compared using ethylene as reactant, and the crystal and morphological structure of the membrane were characterized by XRD and SEM. The results showed that a more compact membrane with high loading of TiO₂ but lower photocatalytic activity of unit TiO₂ mass was obtained by electrophoresis compared with dip coating method. The addition of polyethylene glycol (PEG) to the sol of TiO₂ could improve the specific photocatalytic activity (ethylene conversion per unit mass TiO₂ and unit area of membrane piece) of the electrophoresis-membrane prepared from the sol, but could not change the specific photocatalytic activity of the dip-coating membrane from the sol. The ethylene conversion on the electrophoresis membrane prepared from the sol containing PEG (50 g·L^-1) was 9 times of that on the dip coating membrane. The effect of PEG on the properties of electrophoresis-membrane of TiO₂ was attributed to the change of electrokinetic properties of sol. Addition of PEG decreased ζ potential value of the sol and the mobility of the sol particle, increased viscidity of the colloid, thus decreasing both the electrophoresis deposition velocity of colloid particles and the electroosmosis velocity of diffuse layer of colloid particles. These favored the formation of a low compact and porous membrane on the electrode in electric field, and thus increasing the availability of TiO₂ in photocatalytic process.     

C2H4的微波场助气相光催化氧化

用溶胶－凝胶法制备了多孔性TiO2和SO4^2-/TiO2催化剂,对其结构进行了表征,并以C2H4为模型反应物考察了微波对催化剂的光催化氧化反应性能的影响。在微波场中TiO2和SO34^2-/TiO2催化剂的光催化氧化性能得到明显改善,无微波场时乙烯转化率分别为20％（TiO2)和41％（SO4^2-/TiO2),而在微波辐射和紫外光的同时作用下乙烯转化率分别提高到27％和62％,SO4^2-／TiO2催化剂的微波场助效应更为显著。     

纳米ZnO的制备及发光特性研究

The samples of nano-size ZnO were prepared by precipitation, hydrolysis, sol-gel method and characterized by X-ray diffraction, Uv-Vis diffuse reflection spectrum, and time resolved luminescent spectrum. The results showed that the crystallite dimensions of all ZnO samples were coarsening with increasing annealing temperature and the grain sizes prepared by sol-gel method were obviously smaller than the others prepared by precipitation and hy-drolysis method. Under excitation of monochromatic light of wavelength 300nm, a strong and broad photolumines-cence (PL) emissions were observed in the wavelength range of 420～780nm. As the grain size decreased, the PL peak positions moved to shorter wavelengths. And as the annealing temperature increased, the peak intensity de-creased. The photoluminescence decay profile of ZnO was well described by three decay components of 46ns, 330ns and 1630ns.     

微波辐射对TiO2制备及其光催化氧化乙醛性能的影响

采用微波辐射与常规加热法由TiO₂溶胶制备出TiO₂催化剂，采用高频低功率微波-光催化装置考察了微波对两种催化剂上CH₃CHO光催化氧化转化率和产物分布的影响。结果表明，微波干燥制备的TiO₂晶体比普通加热制备的TiO₂晶体对乙醛有更高的光催化活性和更强的氧化能力，且它们对乙醛光催化氧化的途径不同，前者的初始中间体为甲醛和甲酸，后者的初始中间体却为乙酸。还发现，微波辐射对两种样品上乙醛的光催化转化率有不同的影响，对微波辐射法所制样品的影响比对常规加热法所制样品的影响显著。微波辐射通过场效应可加速光催化初始中间体的转化，但它不改变光催化反应的途径，反应途径取决于光催化剂的特性。     

微波法制备SO2-4/TiO2催化剂及其光催化氧化性能

采用微波法、混合加热法和常规加热法制备/TiO2催化剂,运用XRD、BET、DRS及LRS光 谱测定等技术对催化剂的结构进行了表征,并以光催化降解C2H4为模型反应考察了不同制备 方法对催化剂的光催化氧化反应性能的影响.研究结果表明,微波法制备的/TiO2催化剂的光 催化氧化性能得到明显改善,对乙烯转化率为80％,而混合加热法和常规加热法制备的样品乙 烯转化率分别为58％和41％.微波辐射制备的催化剂锐钛矿相含量高、比表面积大,光吸收阈 值增大;并且拉曼散射光谱向低波数方向移动,有助于增加光致电子的跃迁几率,提高多相光 催化过程的本征量子效率.     

Nafion薄膜中单分散TiO2纳米晶体的合成

采用全氟化离子聚合物薄膜(钠型Nafion薄膜)作模板合成了平均直径为4.0nm的TiO₂晶体粒子。利用高分辨电子显微镜(HRTEM)、X-射线衍射仪(XRD)和紫外-可见光谱仪(UV-VIS)，对Nafion中TiO₂的含量、粒子大小分布、相变条件、纳米晶体微观型貌及其结构、Nafion薄膜结构和TiO₂粒子形成机理等进行了研究。研究结果表明，Nafion中Ti⁴⁺含量不仅与起始原料有关，还与起始物浓度有关。TiO₂在Nafion中的形成速度主要受控于水在膜中的扩散速度，而TiO₂晶体粒子的大小与分布则取决于Nafion的孔径，与起始原料种类以及晶化条件无关。文中还探索了无定型TiO₂转变成单分散晶体的各种途径，详细讨论了TiO₂晶体粒子合成的影响因素。     

二氧化钛基固体超强酸的结构及其光催化氧化性能

采用溶胶－凝胶法制备了多孔性,大比表面积的ＳＯ４＾２－／ＴｉＯ２固体超强催化剂,运用ＸＲＤ,ＢＥＴ比表面积测定,ＸＰＳ和ＵＶ－Ｖｉｓ反射光谱等技术对该催化剂的结构,表面状态以及半导体特征进行了表征,并通过ＣＨ３Ｂｒ,Ｃ６Ｈ６和Ｃ２Ｈ４等典型有机物的气相光催化氧化反应。