Preparation, Characterization and Application of Semiconductor Nanoparticulate Films

尺寸量子化的半导体纳米晶具有从块体材料到分子的瞬变性质，一直是人们非常感兴趣的研究课题。利用溶液中的悬浮颗粒进行了许多研究。我们研究了纳米颗粒薄膜的制备方法和所制备的薄膜的性能。(1)利用聚乙烯吡咯烷酮(PVPD)稳定的二氧化钛纳米粒子在异丙醇中的电泳沉积，实现了纳米二氧化钛粒子在PVPD凝胶膜中的固定化。所制得的凝胶膜对硝酸根离子和二氧化碳还原生成氨和甲醇具有较高的光催化活性。如果在硝酸根离子和二氧化碳同时存在的情况下对这些薄膜进行照射，尿素就会被光化。(2)以Ti(OEt)_4和Si(OEt)_4为原料，采用Sol-Gel法制备了二氧化钛纳米粒子固定化薄膜。二氧化碳在薄膜上的光还原反应生成一氧化碳和甲酸盐，两者的比例受所用溶剂的介电常数的影响，甲酸盐的比例随所用溶剂介电常数的增加而增加。(3)采用自组装化学方法，将硫化镉纳米粒子共价固定到Au(111)表面，制备了硫化镉纳米粒子单层薄膜。STM测试表明，所得到的单层膜由直径为2-3 nm的纳米粒子组成，没有团聚。实现了单个纳米粒子的隧道光谱，并成功测定了硫化镉纳米粒子的能级结构。

Size-quantized semiconductor nanocrystals possess transient properties from bulk materials to molecules and have been very interesting research subjects. Many researches have been performed using suspended particles in solution. We have investigated preparation methods of nanoparticle films and properties of the prepared films. The following results were obtained in the present study.(1) Immobilization of size-quantized titanium dioxide particles in polyvinylpyrrolidinone (PVPD) gel films was accomplished using electrophoretic deposition of titanium dioxide nanoparticles stabilized by PVPD in 2-propanol. The obtained gel films had high photocatalytic activities for reduction of nitrate ion and carbon dioxide to give ammonia and methanol, respectively. If these films were irradiated in the presence of both nitrate ion and carbon dioxide, urea was photoformed. (2) The films of titanium dioxide nanoparticle immobilized in silica matrices were prepared using the sol-gel technique with hydrolysis of Ti (OEt) _4 and Si (OEt) _4. The photoreduction of carbon dioxide on the prepared films gave carbon monoxide and formate as the reduction products and the ratio of those two kinds of products were influenced by the dielectric constant of the solvents used ; the fraction of formate increased with increase of the dielectric constant of solvent used. (3) The monolayr film of cadmium sulfide nanoparticles was prepared by covalently immobilizing cadimium sulfide nanoparticle to Au (111) with use of chemistry of self-assembling. STM measurements revealed that the obtained monolayr film was composed of the nanoparticles of 2-3 nm diameter without aggregation. Tunneling spectroscopy of a single nanoparticle could be performed, and the energy structure of cadmium sulfide nanoparticle was successfully determined.