光催化纳米材料体系表面缺陷态的超快光谱与动力学研究

The mechanistic studies relating to the surface defect states of photocatalytic nanomaterial systems are currently still at the qualitative, semi-empirical stage. This project is devoted to the ultrafast spectroscopy and dynamics studies (featuring resolution from both energy and time domains) on several selected model nanomaterial systems (such as MoO3, MoS2, BiOCl, BiOBr, and C3N4 as well as their composite nanomaterials formed with metallic nanoparticles, metal-organic framework structures, quantum dots, and graphene materials). Our experiments will be performed by means of femtosecond time-resolved pump-probe spectroscopy (UV/visible pump & broadband white-light continuum probe), with the assistance of other spectroscopic tools (such as absorption, photoluminescence, and positron annihilation spectroscopy) and a variety of structural characterizations. By parameterizing the structural and electronic properties of the surface defect states through various structural control techniques utilized in material synthesis, we attempt to look carefully into the effects of the parameter variation on the transient spectral variation and kinetics/dynamics of close relevance to the surface defect states and then to establish quantitative, theoretical models to describe such effects. We aim at acquiring basic, new knowledge on microscopic mechanisms underlying the surface defect states involved in the model photocatalytic nanomaterial systems under investigation, so as to provide fresh, mechanistic perspectives toward rational design and optimization of the photocatalytic nanomaterial systems. This project will target original and exploratory research and put emphasis on the high-quality collaborations from material synthesis/control, advanced spectroscopic characterization/elucidation, and theoretical modeling/analysis.

光催化纳米材料体系表面缺陷态的机理研究尚处于定性的半经验阶段。本项目拟针对若干模型光催化纳米材料体系（如MoO3、MoS2、BiOCl、BiOBr、C3N4等及其与金属纳米粒子、金属有机骨架结构、量子点、石墨烯类材料的纳米复合结构等），开展能域和时域分辨的超快光谱与动力学机理研究。将以飞秒时间分辨的泵浦-探测技术（紫外/可见光泵浦-宽带超连续白光探测）为主要手段，辅以吸收、荧光、正电子湮灭等谱学及多种结构表征手段。通过材料合成方面的各种调控手段，参量化表面缺陷态的结构和电子态性质，探究这些参量变化对表面缺陷态相关的瞬态谱学与动力学行为所产生的效应，构建定量化理论模型，获得光催化纳米材料体系表面缺陷态微观作用机制方面的原理性新认识，以期为相关材料体系的理性设计和优化提供机理层面的新视角。本项目定位于源头创新的探索性研究，注重材料合成与调控、先进谱学表征与解读、理论建模与分析三方面的优质协同。

本项目针对光催化研究领域相对匮乏且不甚明了的纳米材料体系表面缺陷态机理研究，选取若干模型光催化纳米材料体系（如金属有机骨架及其与金属纳米粒子的复合结构、微量In掺杂的CdS纳米棒、氧空位BiOBr纳米片、g-C3N4及其复合结构、量子点、黑磷纳米片等），深入细致地开展了能域和时域分辨的超快光谱与动力学机理研究。以飞秒时间分辨的泵浦-探测技术（紫外/可见光泵浦-宽带超连续白光探测）为主要手段，辅以吸收、荧光、拉曼等谱学及多种结构表征手段。通过材料合成方面的各种调控手段，参量化表面缺陷态的结构和电子态性质，探究这些参量变化对表面缺陷态相关的瞬态谱学与动力学行为所产生的效应，结合理论模拟和计算，获得了光催化纳米材料体系表面缺陷态微观作用机制方面的一些原理性新知，为相关光催化纳米材料体系的理性设计、优化和调控提供了机理层面的启迪和指导。本项目的顺利完成，源于材料合成与调控、先进谱学表征与解读、理论建模与分析这三方面的优质协同。