基于激子过程调控的层状铋氧基半导体光催化氧分子活化性能研究

As an important photocatalytic reaction, semiconductor-based molecular oxygen activation that is closely related to the relevant photoexcitation processes has drawn tremendous attention. Traditionally, most researches have focused on the regulation of band structures and photogenerated charge-carrier behaviors, whereas the impacts of electron–hole interaction-mediated excitonic effects on the relevant photocatalytic performance have seldom been considered. As for semiconductors with confined structures, significantly promoted Coulomb interactions between photogenerated charge carriers can be expected. In this case, excitons tend to be the major photoinduced species, which would dominate the involved photoexcitation processes, thus giving rise to diverse behaviors on photocatalytic molecular oxygen activation. In this project, by taking layered bismuth-oxide-based semiconductors with hetero-layered structures as prototypes, we will focus on the involved photoexcitation processes for pursuing optimized photocatalytic molecular oxygen activation performance. By means of advanced characterization techniques and theoretical simulations, we will interrogate the involved excitonic processes in layered bismuth-oxide-based semiconductors with specific structural factors like dimensions, facets, defects, heterojunctions, etc. The relationship between excitonic processes and structural factors will be emphatically highlighted, which will provide guidance for excitonic regulation via structural engineering, thus leaving optimized photocatalytic molecular oxygen activation performance. The anticipated results of the project will not only establish in-depth understandings on the mechanism of photocatalytic molecular oxygen activation in layered bismuth-oxide-based semiconductors but also pave the way for designing high-efficiency photocatalysts via excitonic engineering.

作为一类重要的光催化反应，基于半导体光激发过程的氧分子活化研究长期以来被局限于材料的能带结构优化和载流子行为调控方面，而由电子–空穴相互作用导致的激子效应对其氧活化性能的影响却往往被忽略。对于具有限域结构的半导体材料，显著增强的电子–空穴相互作用可能使得激子成为主要的光生物种，影响甚至主导材料的光激发过程，进而对其氧分子活化行为产生影响。本项目拟以具有交替排列异质层结构的层状铋氧基半导体为研究对象，聚焦材料的激子过程，开展氧分子活化性能优化研究。申请人拟结合现代物理表征手段和理论模拟，考察具有不同维度、晶面、缺陷、异质结等结构因素的层状铋氧基材料的光激发过程，揭示结构因素对材料激子过程的影响机制，并在此基础上开展激子过程调控研究，进而实现光催化剂氧分子活化性能的优化。项目预期将为层状铋氧基半导体的光激发过程研究提供新认识，同时也为通过激子过程调控实现高效氧分子活化光催化剂的设计提供新思路。

光催化氧分子活化在污染物处理、选择性合成、光动力学治疗等方面具有重要的应用前景，而相应的先进光催化剂设计是该领域研究的关键。传统研究主要关注催化剂载流子特性调控，而对于具有限域结构的光催化剂，由电子-空穴相互作用增强导致的激子效应会显著影响体系的氧分子活化性能。针对这一关键科学问题，项目负责人聚焦具有交替排列异质层结构的层状铋氧基半导体材料，开展基于激子过程调控的光催化氧分子活化性能优化工作。在本项目实施过程中，发展了层状铋氧基半导体合成新方法，实现了系列结构因素（如空位、空位簇、杂原子）的可控引入；结合理论模拟与谱学分析，系统考察了体系光激发特性，揭示了不同结构因素对体系激子/载流子行为的影响规律与作用机制；在理解不同光生物种行为对体系光催化氧分子活化行为的影响基础上，发展基于激子过程调控的层状铋氧基半导体催化剂设计工作，实现了活性氧物种生成的效率与选择性的优化。该项目为理解限域体系光生物种行为与光催化性能的关联、优化体系光催化小分子活化性能提供了新视角。基于上述研究，负责人在J. Am. Chem. Soc.、Angew. Chem.、Adv. Mater.、CCS Chem.等国内外重要期刊发表论文13篇。