钛基钙钛矿型光催化材料的微观结构调控及光生电荷传输行为研究

Perovskite photoactive functional materials have received growing attention, but most research has focused on materials design and functional assessment, while their microstructures modulation and photo-generated charge transportation are relatively less studied. Based on density functional theory simulations, this project aims to design series of titanium-based perovskite complex oxides, and synthesize them by molten salt methods. Morphology controllable synthesis will be achieved via regulating the molten salt composition, sintering temperature etc., thus to regulate the exposed facets, obtaining the interfaces in favor of high activity sites; Bandgap engineering is achieved by adjusting elements or defects positioning in the crystals; Taking advantage of co-catalyst, the local interface of the microstructure will be modulated for improved efficiency of photoinduced charge transportation and separation. Furthermore , using modern spectroscopy techniques including time-resolved laser spectroscopy, Raman microscopy , transient photovoltaic, electron energy loss spectroscopy and surface spectroscopy etc., combined with molecular probes , the degree of crystallinity, particle size , morphology, crystal surface microstructure (exposed surface active sites , micro- distribution of oxygen defects / vacancies , etc. ) and their relationship with the photo-generated charge transfer behavior and photoactivity will be systematically studied. Through this project, we will gain a profound understanding of the microscopic physical and chemical processes involved in perovskite complex oxides, especially their interfacial charge transfer mechanism, laying down fundamentals for their structure regulation, and function optimization.

钙钛矿结构光功能材料日益受到人们重视，目前大多数研究主要集中于材料设计与功能评估，而对其微观结构调控及光生电荷行为的研究相对较少。本项目以密度泛函理论模拟为基础，设计系列钛基钙钛矿复合氧化物，并通过熔盐法等进行合成。通过调控熔盐种类、组成、烧结温度等条件实现不同形貌材料的可控制备，调控晶体暴露面，获得高活性位点的优势界面材料；通过调整不同结晶学位置上的元素或缺陷位来调节光催化剂的能带结构，实现材料的能带剪裁；借助助催化剂作用，调控界面局域微结构，提高光致电荷传输与分离效率。在此基础上，利用时间分辨激光光谱、显微拉曼、瞬态光伏、电子能谱及表面光谱学等，结合分子探针，系统研究粒子结晶度、尺寸、形貌、晶面微观结构（暴露面、活性位点、氧缺陷/空位分布等）与光生电荷传输行为及光活性的关系，揭示表界面电荷转移机制，为钙钛矿光催化材料结构调控、功能优化和理解其光催化的机理、机制提供理论支持。

钙钛矿结构光功能材料日益受到人们重视，目前大多数研究主要集中于材料设计与功能评估，而对其微观结构调控及光生电荷行为的研究相对较少。在本项目执行过程中，以密度泛函理论模拟为基础，用CASTEP、VASP 模块等方法对钙钛矿体系CaCu3Ti4O12等光催化剂的能带结构、态密度、费米能级、杂质能级、禁带宽度、能带组成、表面吸附等进行估算，设计并利用熔盐法合成了全新组成和结构的可见光响应的光催化剂，通过改变熔盐法合成条件实现对材料维度、尺寸、晶体暴露面的调控，获得高活性位点的优势界面材料，并研究了形貌调控的机理、机制。在此基础上，利用稳态（荧光、拉曼等）分析和动态（时间分辨电子自旋共振、瞬态荧光等）分析，结合分子探针（包括CO2和NO的催化转化、抗生素降解、光催化活性物种等），探究了形貌、组成以及暴露面对光催化过程中微观物理化学过程及催化活性的影响，揭示表界面电荷转移机制，为光催化材料结构调控、功能优化和理解其光催化的机理、机制提供了理论支持。.通过本资助项目，在国际刊物 Nature Communications、 ACS Catalysis、 Journal of Catalysis等上发表论文24篇（其中SCI一区文章15篇），申请中国发明专利8项，培养研究生6名，其中已毕业博士生2名，硕士生4名。