异质结光催化材料的设计及其光电和催化性能本质规律研究

Developing heterojunction photocatalysts with high activity via composition of two or more semiconductors is a main research direction to construct novel photocatalysts. In this project, two kinds of heterojunction photocatalysts will be chosen as research objects (one type is TiO2(A) and NaNbO3(B), whose positions of conduction band and valance band are close to each other; the other type is g-C3N4(A) and WO3(B). g-C3N4(A) has more negative conduction band and WO3(B) has more positive valance band). The project will reveal the transfer mechanisms of the photogenerated carriers in the heterojunction structure and expound the electroconductibility of heterojunction photocatalysts with different components by studying the influences of the contents of A and B on the photocatalytic reduction/oxidation performance of A/B and B/A heterojunction photocatalysts, respectively. The optimum conditions for the preparation of the heterojunction photocatalysts will be determined by systematic investigation of the hetero-structure, interface composition, chemical state and surface distribution of the elements of the hetero-photocatalysts. The mechanisms and the natural laws for the effect of electroconductibility on the transfer of the photogenerated carriers and the photocatalytic performance will be revealed by means of (1) systematic investigations of the electroconductibility of the heterojunction photocatalysts with different components, and (2) subsequent theoretical calculations and the correlation analysis. The research will not only reveal the photocatalytic reaction behavior of the heterojunction photocatalytic materials, but also enrich the basic knowledge of photocatalysis, and thus have important theoretical and practical significance.

构建具有高光催化活性的两种或者多种半导体的异质结光催化材料，是目前新型光催化剂设计的主要方向之一。本项目以两类异质结光催化剂为例（TiO2(A)和NaNbO3(B)即两者的价带位和导带位相近；g-C3N4(A)和WO3(B)即导带位较负和价带位较正的半导体）作为研究对象，详细研究A-B异质结催化剂（A/B，B/A）中A的量对A/B和B的量对B/A光催化氧化和还原活性的影响，揭示异质结中光激载流子迁移的机制；阐明不同组分异质结光催化剂的导电性。通过对光催化材料的结构、界面组成及化学状态和表面元素分布等的系统研究，阐明制备上述异质结光催化材料的最佳条件。通过对不同组分异质结光催化剂导电性的详细研究，经过理论计算、进行关联分析，揭示导电性对光激载流子迁移和光催化活性影响的机制和本质规律。以上研究不仅可以揭示异质结光催化材料的反应特征，而且对丰富半导体光催化的基础知识都有重要的理论和实际意义。

构建具有高的光催化氧化和还原能力的两种或者多种半导体的异质结光催化材料，是目前新型光催化剂设计的主要方向之一。本项目以TiO2，ZnO，KNbO3，g-C3N4和WO3组成的异质结光催化剂为研究对象，详细研究A-B异质结催化剂（A/B，B/A）中A的量对A/B和B的量对B/A光催化氧化和还原活性的影响，揭示异质结中光激载流子迁移的机制（带-带转移和Z-型转移）；阐明不同组分异质结光催化剂的导电性。通过对所制光催化材料的表面结构、晶体结构和电子结构、界面组成及原子或离子的化学状态和表面元素分布等的系统研究，阐明制备上述异质结光催化材料的最佳条件。通过对不同组分异质结光催化剂导电性的详细研究，经过理论计算、进行关联分析，揭示导电性对光激载流子迁移和光催化活性影响的机制和它们之间的内在本质规律。.本项目提出了相对p-n结概念。当相对p-n结中内生电场的方向与光生电子和空穴的迁移方向一致时，其光生电子和空穴发生带-带转移；当相对p-n结中内电场的方向与光生电子和空穴的迁移方向相反时，光生电子和空穴将发生Z-scheme转移。相对p-n结概念的提出不仅对理性设计高活性异质结光催化剂具有重要的指导作用，而且对揭示其它各类光催化剂（例如阴离子掺杂、过渡金属阳离子掺杂、贵重金属沉积、同质异构结、不同晶面异质结等等）光生电荷载流子的迁移方向都有重要的指导意义。