基于过渡金属氧化物纳米片的半导体材料组装及构效关系研究

Composite functional materials and devices, which are built through assembling of low dimension scale-units, have become one of hot research interests due to their unique physicochemical properties in recent years. However, only a few studies have been focused on their assembly mechanisn and structure- activity relationship. In this project, Niobia (or Titania)-based oxide nanosheets and transition metal oxide or their composite nanocrystals are used as the object to fabricate the composite materials. The physicochemical changes in the assembly process are specially focused, and the adsorption feature and the photocatalytic activity for selective oxidation of sulfides are used as evaluation reactions. The assembled mechanism and the structure-activity relationship will be explored. By regular and stable niobia (or titania)-based nanosheets are prepared by their layered precursors respectively, dispersing transition metal oxide or their composite nanocrystals with specific properties, which are semiconductor with special adsorption for sulfides such as Fe2O3 and ZnO, the interactional modes between nanosheet and nanocrytal, dispersion and aggregation mechanism of oxide species on nanosheets are discussed. The structure, the photoelectrochemical characterization, structural synergy and functional coupling for composite photocatalytic materials are characterized by the means of powder X-ray diffraction (XRD), transmission electron microscopy (TEM), atomic force microscopy (AFM), laser Raman spectroscopy (LRS), UV-vis diffuse reflectance spectroscopy(UV-vis DRS), and Photoluminescence spectroscopy (PLS), the dispersion and aggregation model for transition metal oxide species on the metal oxide-based nanosheets and assembled mechanism sill be established, furthermore, the functional design theory and controllable assembled technology be developed based on composite functional materials.

由低维尺度单元组装的功能材料与器件因其独特的物理化学性质已成为近年来研究的热点之一，但"组装机理"和"构效关系"研究相对薄弱。本研究采用铌（钛）基氧化物纳米片与过渡金属氧化物或复合氧化物纳米微晶组装体系为研究对象，以构建复合功能材料为目标，复合过程中物理化学变化为研究重点，吸附和选择性光催化氧化有机硫化物为性能评价手段，研究纳米无机复合催化材料组装机制与构效关系。通过制备规整、稳定的铌（钛）基氧化物纳米片，分散具有特定功能的过渡金属氧化物或复合氧化物，如Fe2O3和ZnO纳米微晶，研究分散物种与纳米片作用方式、分散与聚集机理。通过XRD、TEM、AFM、LRS、UV-vis DRS和PLS等表征技术以及光催化活性评价，对复合催化材料结构、光电化学特征以及结构协同与功能耦合效应进行表征，建立过渡金属氧化物在氧化物纳米片载体上的分散模型与组装机制，发展复合催化功能材料的设计理论与可控组装方法。

本研究将采用高温固相法等方法合成的层状铌（钛）基氧化物或复合氧化物作为前驱物，通过离子交换和剥离-组装等方法构建无机复合功能材料。利用XRD、TEM、TG-DSC、低温N2吸附、LRS、UV-vis DRS、XPS、Mott-Schottky曲线测定等技术研究了复合材料中等技术研究了复合材料中客体氧化物纳米粒子与主体纳米片（卷）之间的相互作用以及其他物理化学变化，探讨分散相氧化物在纳米片表面的分散与聚集情况。选用亚甲基蓝作为光催化氧化活性表征的探针物质，考察了复合材料中主客体间的协同作用，同时，研究了复合功能材料对有机硫化物的光催化氧化性能。结果表明，分散氧化物与纳米片（卷）之间存在着相互作用，其相互作用的特征随着客体氧化物酸碱性、自身成核、团聚以及与纳米片（卷）表面特征而变化；主体纳米片材料表面活性羟基的酸性也明显地影响着主客体间的相互作用。这种变化导致纳米粒子在纳米片（卷）表面生长机理不同，分散状态也不尽相同。主客体间的协同作用取决于他们之间的相互作用强度与特征，同时，主客体本身的导带与价带电位的匹配直接影响着光生电子与空穴的流向也直接影响着光催化活性。给予这些实验基础，分散相氧化物在纳米片表面的分散模型被建立，材料的功能设计和可控组装方法也被建立。在协同去除有机硫化物方面，还考察了锰基化合物复合材料的性能，分散相Ag对S原子良好的亲和作用促进了锰基氧化物的吸附作用，从而促进了有机硫化物氧化降解作用。