非金属含氧酸镧类材料的光催化还原CO2性能及作用机理研究

The efficient conversion and utilization of CO2 is one of the most important issues in the field of environment and energy. Mimicking photosynthesis by using the photocatalytic reduction of CO2 is considered as a green approach for the carbon fixation. However, the efficiency of photocatalytic reduction of CO2 is still low at the moment. The key to the effcient utilization of CO2 is the development of high efficient photocatalysts for CO2 reduction. Based on the special structural and physicochemical properties of lanthanum nonmetallic oxysalts, such as the high CB position, the alkaline surface and the empty La 4f orbital providing a shallow trap for photo-generated electrons, and our pre-discovery that lanthanum nonmetallic oxysalts, such as LaCO3OH and LaPO4, exhibit photocatalytic activity for the reduction of CO2 to methane with pure water under UV irradiation, a new idea of developing lanthanum nonmetallic oxysalts as the photocatalytic material for CO2 reduction is proposed. With an aim to develop high efficient lanthanum nonmetallic oxysalts photocatalysts for CO2 reduction, this project intends to investigate the control synthesis of catalyst and the performance of photocatalytic CO2 reduction, the relationship between the composition/structure and the performance of lanthanum nonmetallic oxysalts. Based on these results, hopefully we can elucidate the essential factors affecting the performance of photocatalytic CO2 reduction and clarify the commonalities and differences between the catalysts and traditional semiconductor photocatalysts, so as to develop new and efficient La-based photocatalytic CO2 reduction materials. This results not only shows great theoretical significance for CO2 fixation, but also enriches the contents of photocatalysis and expands the practical applications of rare earth materials.

利用光催化还原CO2来人工模拟光合作用是一种绿色的人工固碳技术，然而目前光催化还原CO2的效率很低，高效光催化材料是实现这一技术应用的关键。根据非金属含氧酸镧材料具有高导带位置、碱性表面、浅势捕获光生电子的La 4f空轨道等特殊结构和物理化学性质，并基于LaCO3OH和LaPO4在紫外光照下,在纯水介质中可把CO2还原成甲烷的前期探索发现，本项目提出研制系列非金属含氧酸镧类材料，并开展其光催化还原CO2作用机理研究的新思路。将详细考察催化剂的控制合成、光催化还原CO2的性能，研究非金属含氧酸镧类材料的组成、结构与其性能之间的关系，揭示影响其光催化还原CO2性能的本质因素，阐明其与传统半导体光催化剂在光催化还原CO2上的共性与差异，从而开发出高效还原CO2的La基新型光催化材料。该研究不仅对CO2的固定具有很好的理论指导意义，而且对于丰富光催化理论，拓展稀土材料的实际应用具有重要的实际意义。

本项目以研究非金属含氧酸镧类材料光催化还原CO2的性能及作用机理为主要内容，重点开展 LaPO4等非金属含氧酸镧类材料的控制合成、光催化还原CO2的性能以及构效关系研究，探究影响其光催化CO2还原性能的本质因素，取得了如下主要进展：（1）研制出包括LaPO4和La2Sn2O7等10种不同组成或结构的光催化材料；（2）详细考察了制备的催化剂样品光催化CO2还原的活性和稳定性，研究了组成、结构对光催化行为的影响，对制备样品的组成和结构进行了优化；（3）阐明了LaPO4基光催化剂以及一些新型光催化材料的作用机理；（4）通过原位表征和理论计算揭示CO2等反应物分子在材料表面的反应机制和动力学行为。研究结果共发表SCI学术论文13篇，获授权发明专利3件，对丰富光催化科学基础、指导新型高效还原 CO2光催化剂的设计开发具有重大的理论和实际意义。