非贵金属催化材料的表界面结构调控及其在光催化CO2转化中的构效关系研究

Photocatalytic conversion of CO2 into value-added chemical fuels is an intriguing approach that simultaneously meets the demands for easing energy shortage and reducing CO2 level. A variety of inorganic semiconductors (e.g., TiO2) have been evaluated as heterogeneous photocatalysts for the conversion of CO2 into carbon-based products. Unfortunately, all heterogeneous semiconductor catalysts reported thus far exhibit unsatisfactory catalytic activity and selectivity, and rely on expensive noble metals as catalytic sites, mainly because of their wide energy bandgap, system complexity and technical limitations. Thus designing and synthesizing ideal non-noble catalysts for photocatalytic CO2 conversion will be a grand challenge for scientists and also the key issue to develop artificial photosynthesis in the future. It has been reported that the surface and interface structures of metal oxides may significantly impact on the key steps of light absorption, photoexcited carrier behavior, and molecular adsorption and activation involved in the photocatalytic process. However, the detailed working mechanisms and structure-property relationships remain elusive. In this project, we propose to establish the structure-property relationships between surface/interface structures and photocatalytic performance by selecting earth-abundant non-noble cobalt-based oxides as catalytic centers, precisely controlling their surface/interface structures, in-situ characterizing the structures with synchrotron radiation characterization techniques, as well as analyzing their performance in each step of photocatalysis. Based on that the investigations, we will formulate the designing rules for the surface/interface structures towards photocatalytic CO2 conversion. With theoretical calculations, this project will provide profound insights into understanding the mechanism of photocatalytic CO2 reduction as well as designing novel high-performance heterogeneous catalysts.

模拟光合作用将CO2转化成高附加值的化学燃料不仅是发展可再生能源的新途径，且碳的循环利用可缓解日益严重的温室效应。以TiO2为代表的异相光催化体系在CO2转化研究中取得可喜的成果，但受体系复杂和技术上限制，在效率和产物选择性上一直没有实质性的突破，并且依赖贵金属作为催化中心。因此，设计合成理想的非贵金属CO2转化催化剂是科学家面临的挑战，也是解决人工光合作用的核心问题。表界面结构对光催化过程中光子吸收、光生电荷行为及分子吸附活化等关键步骤具有重要的影响，然而其作用机制与构效关系尚不明晰。本项目以非贵金属Co基氧化物为催化中心，配合同步辐射表征技术，通过精细调控和原位表征，探究表界面结构在光催化过程中的作用机制，从而建立催化中心表界面结构与光催化性能的构效关系；总结出针对于光催化CO2转化催化剂的表界面结构设计原则，并结合理论计算，深入认识反应机理，为理想新型高效催化剂的设计与合成提供指导。

模拟光合作用将CO2转化成高附加值的化学燃料是发展可再生能源的一种新途径，可同时应对能源危机和CO2污染。近年来无机半导体异相光催化体系在CO2转化研究中取得一些进展，但其效率和产物选择性一直没有实质性的突破，并且依赖贵金属作为催化中心。因此，设计合成理想的非贵金属CO2转化催化剂是实现工业化应用的核心问题。表界面结构是影响光催化剂性能的重要因素，其理性设计可以有效提高光催化的性能。然而，如何理性设计光催化剂的表界面结构，以及其作用机制与构效关系尚不明晰。本项目针对该瓶颈问题，通过精细调控表界面结构和发展先进原位同步辐射表征技术，探究了表界面结构在光催化CO2转化过程中的作用机制，取得了一些突破性进展：（1）通过对单原子催化中心表面结构的设计和优化，利用石墨烯在均相和异相催化体系间架起了桥梁，强调了电荷动力学调控对于高效光催化的作用。（2）发现通过掺杂的方式可以精修催化剂的缺陷态，可以促进表面缺陷位点对底物分子的高效活化和电子转移；从而有效地提高光催化的效率，展示了催化位点电子结构的调控对催化反应的重要性。（3）发展了一种在CuO2表面原位生长Cu基MOFs的简便方法，通过超快光谱研究论证了所形成的界面可以显著促进光生电荷分离及转移，为设计先进的复合光电极提供了新的见解，并强调了界面电荷动力学在光电催化CO2转换中的重要作用。（4）利用原位时间分辨同步辐射X射线吸收谱，成功捕捉到均相催化剂在反应过程中的动态配位和电子结构信息，推动了对于高效均相光催化CO2还原反应机理的理解，为理性设计异相催化剂，特别是异相单原子催化剂，提供了非常有价值的信息。相关研究成果在Journal of the American Chemical Society（3篇）、Advanced Materials（1篇）、Chemical Reviews（1篇）等国际期刊上发表论文11篇。