锗酸锌基固溶体光催化材料的设计制备和性能研究

The photocatalytic reduction of CO2 into organic fuels is a most ideal approach for conversion and utilization of CO2. Aiming at several key issues including low efficiency and poor selectivity occurring on current photocatalytic materials, basing on the band-gap engineering and designing fundamental of semiconductors, the project uses a pseudoternary phase diagram method to seek, design and prepare Zn2GeO4-based solid solution photocatalysts with high-performance. The main investigations involoved: (1) Study on the role of incorporated elements in Zn2GeO4-based solid solution system, and the effect of amount and composition of solid solution system on band-gap structure of semiconductor. (2) 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. (3) The composition, band-gap structure, electron structure, adsorption performance, and photocatalytic properties of such materials will be studied systemically to establish the intrinsic correlations between the composition and band structures of Zn2GeO4-based photocatalytic materials and their photocatalytic activities, illustrating the composition and structures of photocatalysts, the dependence of the photocatalytic activities on the composition, band structures and adsorption properties. (4) The activation mechanism of CO2 over these photocatalysts will be clearly elucidated, and the synergic mechanism among doping compositions of Zn2GeO4-based photocatalysts will be clarified in details. These works will offer theoretical guide for the design and preparation of efficient photocatalytic materials for the direct reduction of CO2. Therefore, this project is of great significance in not only promoting preparation chemistry, but designing photocatalytic materials for CO2 conversion.

光催化还原CO2为有机燃料是CO2转化和利用的一条理想途径。项目针对现有材料的CO2光转化效率低和选择性差等问题，基于半导体能带工程设计思路，提出采用绘制(赝)三元相图探寻锗酸锌基固溶体(区)的思想，设计并制备新型锗酸锌基固溶体。研究不同元素的引入在锗酸锌基固溶体体系中的角色，分析不同含量和材料组成的固溶体体系对半导体能带结构的影响；以固溶体能带结构变化为主要着眼点，研究分析不同固溶体体系的系列固溶体光催化剂性能的变化；研究催化剂电子结构、反应物分子吸附性能以及反应活性和产物分布之间的相互关系。阐明CO2在催化剂上的活化机理，揭示锗酸锌基固溶体光催化剂组分协同机制与光活性的本质关系，为CO2还原高效光催化材料的设计制备、改善半导体光催化性能实验方法的建立以及CO2光还原转化的实际应用提供理论指导。该研究无论从制备化学，还是从光催化材料的设计以及CO2的光催化研究上都具有重要的科学研究价值。

把CO2重新还原为有机燃料是化学领域最具挑战性的反应之一，对于解决环境和能源问题意义重大。本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，基于半导体能带工程设计思路，以Zn2GeO4为固溶体构建基体，选择Ga、Sn、Fe、Sb、Ti等作为被引入溶质或溶剂原子，利用高温固态和熔盐等方法系统开发了系列新型锗酸锌基固溶体光催化剂，如N-doped graphene/Zn1.231Ge0.689N1.218O0.782、钛锗酸锌、镓锗铁酸锌、铬锗酸锌、钒锗酸锌、CoxZn2-xGeO4等光催化剂；同时利用溶液化学方法也设计制备了不同纳米结构的锗酸锌及硫化镉异相结等光催化剂。结果表明：多种光催化材料在CO2还原和光解水方面均表现出了较高的性能和催化活性稳定性。本项目通过材料组成的优化设计制备和光吸收、电子结构、光激发特性、氧化还原特性、光生电子和空穴的迁移和分离效率及其对CO2光催化还原性能研究，揭示了不同组成和能带结构的光催化剂组分协同机制与光活性的本质关系，详细研究了光催化材料对光催化CO2还原性能协同作用的影响及规律，为CO2还原高效光催化材料的设计制备、改善半导体光催化性能实验方法的建立以及对CO2光还原转化的实际应用提供一定的理论依据。