LaCoO3外延膜的取向、结构调控及可见光催化性质研究

针对当前广泛应用的TiO2等光催化材料不能利用太阳光谱中可见光的问题，以具有可见光催化活性的钙钛矿结构LaCoO3为研究对象，采用高分子辅助沉积法制备LaCoO3外延膜；借助单晶衬底的诱导和限制作用，通过改变衬底取向，实现对LaCoO3外延膜晶面的定向控制；通过调节LaCoO3外延膜的晶格失配度及应力大小，改变CoO6八面体畸变程度，实现对Co3+晶体场分裂属性的调控；通过研究不同取向及应力调控下LaCoO3的结构变化规律，阐明LaCoO3取向与结构畸变及Co3+晶体场分裂属性的调控机制；结合LaCoO3外延膜的光学吸收谱特征及对有机物进行可见光降解的特点，探明晶面取向、结构调控对LaCoO3能带结构变化、电子跃迁及可见光催化性质的影响机制。研究成果不仅为阐明钙钛矿结构光催化材料的结构与性能调控机制提供科学依据，而且所制备的LaCoO3外延膜对于环境保护和能源利用等也具有重要的实际意义。

Nowadays, photocatalytic materials have gained much attention due to their excellent performance for degradation of persistent organic pollutants. However, most widely-used photocatalysts, such as TiO2, can not effectively utilize the visible light. Therefore, in this program, LaCoO3 with ABO3-type perovskite structure is proposed due to its high visible-light-induced photocatalytic activity. A simple and cost-effective polymer assisted deposition method will be considered to prepare LaCoO3 epitaxial films. In order to control the crystal orientation of LaCoO3 epitaxial film, single-crystal substrates with different orientation will be used. Similarly, CoO6 octahedron distortion and crystal-field splitting characteristic of Co3+ will be changed by the control of lattice mismatch and epitaxial strain. Then the effects of film orientation and epitaxial strain on the structural distortion of LaCoO3 will be discussed for clarifying the control mechanism of film orientation, structural distortion and crystal-field splitting characteristic of Co3+. Based on characterization for spectral absorption property and organic pollutant degradation rate of the LaCoO3 epitaxial films under visible light irradiation, the effects of orientation control and structure modify on the energy band structure, electron transition and visible-light-induced photocatalytic property of LaCoO3 will also be investigated. The results may not only provide scientific guidance for expounding the structure and property control mechanism of visible-light-induced photocatalytic materials with perovskite structure, but also have an important practical significance for environmental protection and energy utilization.