基于金属有机框架构筑新型微纳米复合催化剂及其光还原CO2性能研究

Nowadays, "Greenhouse effect" has caused a series of environmental problems, how to reduce and transform CO2 has become an urgent global problem. Converting CO2 to high value-added low-carbon hydrocarbons by solar energy is able to solve environmental problems as well as to provide a convenient way to store energy. However, the efficiency of photocatalytic reduction of CO2 adsorption by traditional semiconductor materials is generally low. This project is designed to control the synthesis of hierarchical ordered nanostructures, then the functional modifying nanostructures combine with the semiconductor or metal nanocrystalline via orientation interface to build efficient and stable photocatalytic system. The main research contents include the synthesis of hierarchical ordered nanostructures by the restrictive liquid phase assisted by the surfactant, and the high-volume directional fixation is carried out on the surface of the above materials by electrostatic adsorption or in situ reaction. It will build up photocatalytic system with highly efficient light harvesting and separation of photogenerated electron and hole, and high electron mobility. The key research of the project is to analysis the effects of the composition, structure and the surface modification of the nanostructures on the adsorption and the activation properties of CO2. The intrinsic relationship among the structure, properties and function of the nanostructures is elucidated. Also, the synergistic effect of each element is evaluated to reveal the related physical and chemical mechanism. In conclusion, the studies above would provide theoretical and experimental basis for the development and application of excellent photocatalytic materials for CO2 reduction.

“温室效应”引起了一系列的环境问题，如何消减和转化CO2，已经成为全球性的紧迫问题。利用太阳能将CO2催化转化为高附加值的低碳烃类，既解决环境问题也提供了一种便捷储能方式。但目前传统半导体材料光催化还原CO2的效率普遍较低。本项目设计可控合成多级有序纳米结构，功能化修饰后再与半导体或金属纳米晶定向界面复合，构筑高效和稳定光催化体系。主要研究内容包括通过表面活性剂辅助下的限制性液相合成多级有序纳米结构，进一步在上述材料表面利用静电吸附或原位反应进行高载有量定向固定，建立可见光捕获强、有效分离光生电子和空穴和电子迁移率高的复合光催化体系。重点研究材料的组分、结构及其表面修饰对CO2的吸附、活化性能的影响和规律，阐明体系结构-性质-功能之间的内在关系，评估各基元协同催化效应并揭示相关物理化学机制，为具有优异光催化还原CO2性能材料的开发及应用提供理论和实验依据。

通过功能化修饰、掺杂改性及表面态规律、电荷转移机制、光催化反应机理本质的揭示，实现对MOFs基复合光催化材料能隙、缺陷、反应活化位点、光生载流子的分离与迁移等精确调控，探索结构—表面能级—光电能量传递之间的关联；从理论上提出，并在实验上建立获得高效、可见光捕获能力强、可循环利用、在光还原CO2方面有应用前景的环境友好MOFs 基复合催化材料的新方法。主要有：(a) 通过调控反应条件，制备出具有可见光捕获能力强的MOFs多级微/纳材料。并通过功能化的修饰及优化形貌，调节晶格缺陷，探究各因素对其作为光催化CO2还原反应的活性和选择性的影响；(b) 将优化后的可见光响应的MOFs材料，通过煅烧、刻蚀、复合等技术方法制备其衍生材料、异质结构等，探究其组成比例，粒径大小和存在位置对于光催化CO2还原活性的影响，研究改性材料对CO2的吸附活化，光生电荷的产生、传递、分离等还原过程的影响；(c) 基于实验结果，借助理论计算模拟，从分子学和反应动力学角度对CO2的吸附状态，活化过程以及电子在复合体系的传递路径进行深入研究。以系统工程学的方法研究材料的组成、结构与其性能之间的关系。