含缺陷绝缘体光催化净化NOx的机理

The applicants have discovered the interesting phenomena of photocatalysis on insulators with defects. In order to solve the key scientific problems based on this discovery, this proposal tries to realize the control of defect properties for insulators through optimizing the synthesis conditions systematically. The proposal will also investigate the effects of defect types, sites and numbers on the crystal structure, band structure and electronic structure based on first principle calculation method, and then reveal the photocatalysis induced by defects by analyzing the production, transfer and life-time, concentrations and redox behavior of photo-generated charge carriers. Considering the results of light absorption characteristics, transfer and transportation behaviors of photo-generated charge carriers and trapping of reactive radicals, the fundamental of the photocatalysis mechanism of insulators will be revealed. Besides, the light response of the insulators are expected to extend to visible light region to increase the utilization of sunlight via various modification methods. The as-synthesized insulators will be applied in purification of NOx at ppb level. By combination the results of intermediates and final products confirmed by in situ FT-IR spectra, the reaction mechanism of photocatalytic purification of NOx will be elucidated. Based on the results of experimental investigation and theoretical calculation, the relationship between photocatalysts microstructure, defects and photocatalytic activity will be established, which will provide sound technological basis for the future applications in air purification. The present work is expected to open a new research area of photocatalysis with insulators.

申请者在探索中发现了含缺陷绝缘体具有光催化作用的有趣现象。本项目在此基础上针对关若干键科学问题，通过系统优化绝缘体制备工艺条件，实现对绝缘体中缺陷性质的调控；采用第一性原理计算研究缺陷种类、位置和数量对绝缘体晶体结构、禁带结构和电子结构的影响规律，从光生载流子生成转化、浓度及氧化还原行为等角度，揭示缺陷给予绝缘体光催化性能的作用机理。综合光吸收特性、光生载流子迁移转化行为、活性自由基俘获等结果，揭示绝缘体光催化作用的本质；探索运用不同改性方法将绝缘体光催化响应范围拓展至可见光区，增加绝缘体对太阳光的利用率。将绝缘体光催化剂应用于低浓度NOx净化，结合原位红外光谱确定催化剂表面的中间产物和终产物，揭示绝缘体光催化净化NOx的反应机理。综合实验研究与理论计算结果，建立绝缘体微结构、缺陷和光催化性能之间的构-效关系，为其走向空气净化应用提供技术基础。预期本项目可开拓一个绝缘体光催化研究的新领域。

采用化学沉淀法合成了含缺陷的绝缘体，研究了前驱体种类等条件对绝缘体中缺陷的调控。采用实验与理论计算相结合的方法揭示了缺陷给予绝缘体光催化作用的本质原因，确定了缺陷的种类。计算含缺陷的绝缘体的能带结构和电子结构，与无缺陷的绝缘体的理论计算结果对比，揭示了缺陷对绝缘体晶体结构、能带结构和电子结构的影响规律，进而分析了缺陷对光生载流子生成与转化、载流子浓度及氧化还原能力的影响。阐明了金属Ba缺陷在绝缘体光催化作用的机制，为深入认识绝缘体光催化剂提供新的见解。.通过与窄带隙半导体（如BiOI）复合来拓展碳酸盐和硫酸盐绝缘体的光响应范围。采用UV-vis DRS 分析绝缘体的光吸收特性，确定绝缘体光吸收范围拓展的起因；采用光致发光光谱、瞬态光谱和时间分辨荧光光谱等研究绝缘体在紫外光照下载流子的生成、迁移、转化和寿命；通过电子、空穴和其他活性物种的捕获实验确定绝缘体光催化过程中的活性物种，揭示了绝缘体光催化的作用机制。对绝缘体光催化剂进行长时间光照和重复使用，考察了其结构和光催化性能的稳定性。综合材料表征和性能测定结果，建立了绝缘体材料微结构-光催化性能之间的关系。采用原位红外光谱和气质联用仪分析光照过程中催化剂表面和气相中间产物和终产物的浓度和分布，结合光催化过程的载流子的生成转化和自由基俘获结果，综合理论计算的研究结果，阐明了含缺陷的绝缘体光催化氧化NOx的反应机理。.项目负责人以第一或通讯作者在Environmental Science & Technology, Applied Catalysis B: Environmental, ACS Catalysis, Science Bulletin, Chemical Engineering Journal, Chinese Journal of Catalysis, Catalysis Science & Technology等发表标注项目号（21777011）的SCI论文68篇，其中6篇入选ESI高被引论文。在《科学通报》发表中文核心期刊论文3篇。获得2020年教育部自然科学奖二等奖（排1）。