钛酸锌基固溶体复合半导体的构筑及其可见光光催化CO2还原性能研究

Aiming at two key issues including limited conversion efficiency and low sunlight harvesting occurring on current photocatalytic materials, on the basis of the band-gap engineering and designing fundamental of semiconductors, the project uses a phase diagram method to seek, design and prepare Zn2TiO4-based ternary solid solution photocatalysts, while the B site is occuped by two kinds of metal ions in the Zn2TiO4 crystal structure. Combined with the characterization and performance evaluation. The relationship among component, electron sturcture, and performance of photocatalysts and their activation mechansims of manipulating the generation will be be systematacially studied. The main investigations involoved: (1) The changes in band-gap structure of solid solution as the main focus, the proposal studies and analyses the changes in photocatalytic properties of a series solid solution in different systems. (2) The composition, band-gap structure, electron structure, and photocatalytic properties of such materials will be studied systemically to establish the intrinsic correlations between the composition and band structures of Zn2TiO4-based photocatalytic materials and their photocatalytic activities, illustrating the composition and structures of photocatalysts, the dependence of the photocatalytic activities on the a synergistic result of composition and band structures. (3) The synergic mechanism among co-substituted compositions of Zn2TiO4-based photocatalysts will be clarified in details. (4) Some novel principles and new methods to design and prepare new efficient ternary solid solution photocatalysts will be developed. These works will not only offer theoretical guide for the design and preparation of efficient solid-solution photocatalytic materials for the direct reduction of CO2, but also have the most important signification for enriching the foundation of photocatalytic CO2 science and technology.

项目针对现有材料的CO2光转化效率低和光谱响应范围窄的问题，基于半导体能带设计理论，提出利用异价复金属离子共取代钛酸锌部分B位Ti4+制备窄带隙钛酸锌基三元固溶体的设计思路，通过绘制三元相图构建固溶体（区）的方法，结合CO2还原反应电位分布调整钛酸锌B位元素组成，研究固溶体光催化剂的化学组成、电子结构和性能之间的关系，研究异价复金属离子的共取代型固溶体的能级与能带结构及变化规律，确定其固溶体的能带结构和光致电荷转移和分离过程；揭示固溶体半导体组分协同机制与光活性的本质关系，弄清控制固溶体光催化剂性能的关键组成与结构因素；阐明固溶体光催化剂内在构-效关系的光催化增强作用机制，并探索出一条复金属离子共取代型三元固溶体光催化剂的活性产生机制及活性改进新思路和新途径。该研究对指导新型高效固溶体光催化剂的设计制备和丰富光催化还原CO2的基础理论都具有重大的科学和实际意义。

探索有机物燃烧的逆反应—二氧化碳和水反应获取有机物（碳氢燃料）和氧气的反应，具有重大研究意义与应用前景。项目针对现有材料的CO2光转化效率低和光谱响应范围窄的问题，基于半导体能带设计理论，提出利用异价金属离子取代Zn2TiO4的B位部分Ti4+构建钛酸锌基固溶体的设计思路，结合水还原CO2反应至不同产物所需电位要求，通过熔盐、高温固态和水热等方法系统开发了系列新型钛酸锌基固溶体复合光催化剂，如Zn2Ti3O8/ZnTiO3、Zn2TiO4/R-TiO2、Zn2GexTi1-xO4 (0≤x≤0.15)、Zn(1+3x)/2FexGexGa1-2xO2+2x (0<x≤0.15)、CoxZn1-xCr2xGa2-2xO4 (0≤x≤1)、Zn2Ti1-xSnxO4 (0≤x≤1.0)、Zn2-2xTi1-2xFexNbxO4-3x (0<x≤0.15)、CaWO4/Ca2FeTaO6-XNX等。项目研究了各固溶体光催化剂的化学组成、电子结构和性能之间的关系。通过对制备条件和元素协同进行优化并结合能带结构等理论分析，阐明了固溶体光催化剂的组分协同机制和影响光催化剂活性的关键因素。创新设计了一类新的CO2+H2O体系的钛酸锌基固溶体光催化剂，并有效提高了二氧化碳与水反应制备碳基燃料的转化效率。该研究对指导新型高效固溶体光催化剂的设计制备和丰富光催化还原CO2的基础理论都具有重大的科学和实际意义。