卤素诱导Aurivillius结构Bi基材料氧空位的可控构筑及其可见光再生行为机制研究

Aurivillius Bi-based materials with oxygen vacancies have attracted more and more attention because of their unique electron structure and photocatalytic activation of small-molecule gases. But the continuous depletion of oxygen vacancies during the photocatalytic process seriously impacts the photocatalytic efficiency. Non-metallic introduction such as halogen can effectively weaken the Bi-O bond, which provides the possibility for the controllable construction of oxygen vacancies and their visible light regeneration. However, it is still not clear about the controllable construction of oxygen vacancies on Aurivillius Bi-based materials induced by halogen as well as the regeneration mechanism of oxygen vacancies in visible light. This project intends to realize the controllable construction and visible light regeneration of oxygen vacancies on Aurivillius Bi-based materials through the introduction of halogen. Theoretical calculation and various experimental tests will be applied to systematically investigate the influence of halogen and structure of Bi-base materials on oxygen vacancies formation energy. The impact of halogen on photocontrolled oxygen vacancies regeneration and the long-term stable photocatalysis induced by the regenerated behavior will be further studied. On the basis of the above results, the mechanism of optical oxygen vacancies regeneration behavior and its relationship with the photocatalytic performance will be summarized. This study will furnish the basic data and theoretical support for designing highly efficient and stable Aurivillius Bi-based photocatalytic materials with oxygen vacancies for solving environmental and energy problems.

含氧空位Aurivillius铋基材料因其独特的电子结构和在光催化小分子气体活化方面的研究受到广泛关注，然而由于氧空位在催化过程中的不断损耗而严重影响了光催化反应效率。卤素等非金属引入可有效削弱Bi-O键，为氧空位可控构筑及可见光控再生提供了可能。但有关卤素诱导Aurivillius铋基材料氧空位的可控构筑及其可见光控再生行为机制尚不明确。本项目拟通过引入卤素实现Aurivillius铋基材料氧空位的可控构筑和可见光再生，利用理论模拟和实验结合的方式系统研究卤素和Bi基材料结构对氧空位形成能的影响；考察卤素影响下Bi基材料光控氧空位再生行为及该再生行为导致的长效稳定的光催化作用；阐述Aurivillius结构Bi基材料光控氧空位再生行为的产生机制及其与光催化性能之间的关系。为设计合成高效、稳定含氧空位Aurivillius结构Bi基光催化材料进而解决环境及能源问题提供基础数据和理论支持。

实现可见光光催化材料的氧空位可控构筑及可见光辐照下的光控氧空位再生，对最终实现利用太阳能驱动的稳定高效的光催化反应具有重要意义。根据项目书计划，本项目以Bi2MoO6，Bi2WO6等最常见的Aurivillius结构Bi基材料为代表，采用水热、溶剂热等多种方法，首先开展了氧空位的调控和氧空位对CO2,O2和NOx等小分子活化机制研究。通过理论计算和实验相结合的手段发现向{001}晶面暴露钼酸铋上引入氧空位会促使CO2以B1-CO2构型吸附在其表面，主要转化生成高附加值的CH4。发现铋负载的{001}晶面含氧空位钼酸铋材料的光生电子的寿命延长，电子-空穴分离和迁移能力明显加强，超氧负离子和单线态氧等活性氧物种的生成能力明显加强，分子氧活化能力显著提升。通过简单的溶剂热法对Aurivillius结构Bi基材料引入F、Cl、Br、I等卤素离子发现，适量引入卤素离子可有效促进氧空位的产生，特别是针对钼酸铋材料，我们发现Br-可以增强和稳定钼酸铋{001}晶面上的氧空位，而几乎不影响钼酸铋{010}晶面上的氧空位。最后，我们通过简单的卤素离子(F-)修饰方法，在可见光照射下实现了光致变色Bi2MoO6上连续原位生成氧空位，借助ESR、ATR-FTIR、Raman 等多种原位表征分析手段揭示了F离子诱导钼酸铋氧空位可见光下的再生机制及其对NOx深度氧化机制。本项项目研究结果可为设计合成高效、稳定含氧空位Aurivillius结构Bi基光催化材料解决环境及能源问题提供基础数据和理论支持。