微/纳米晶体表面结构的控制及其结构与性能关联的研究

Although great progresses have been achieved in the fundamental studies of the surface structures and corresponding properties of single crystals, in order to provide deep insight into the relationship between the exact surface structures and physical chemistry properties in the practical systems, it is important and urgent to prepare and explore micro-/nano-crystals with well-defined surface structures. In this project, according to the basic principles of crystallography and structural chemistry, we will develop efficient strategies to prepare uniform well-defined micro-/nano- crystals of functional metals and metal oxide. The definite surfaces of these micro-/nano-crystals will be consciously constructed by controlling the crystal growth process via adjusting both thermodynamic and kinetic parameters. The actual structures of the surfaces, including atomic arrangements, orientation, surface defect and adsorption, will be investigated by the electrochemical measurements, spectral analysis, electron microscopy observation, small-angle x-ray scattering (SAXS), x-ray absorption near edge structure (XANES), extended x-ray absorption fine structure (EXAFS), temperature programmed desorption mass spectrometry (TPD-MS), and so on. The formation/stabilization mechanism of the definite surfaces will be revealed based on the sophisticated analysis of the growth process, carefully characterization as well as mathematical simulations. A coherent picture will also be drawn to show how the properties of the as-prepared micro-/nano- crystals can be tuned by the structures of the surfaces. The main purpose of our study is to clarify related theory controlling mechanism of the definite surfaces, explore new methods for determining the surface structures, provide insight into the interaction of different surface structures and corresponding properties at atomic (molecular) scale, and finally build a bridge between the fundamental surface science researches and industrial applications. We are sure that such investigations will begin a new area of physical chemistry in the research of solid and surfaces.

表面化学家在单晶固体表面的物理化学行为和性质等方面取得了许多引人瞩目的成果，但若要深入探讨实际复杂体系中固体表面的结构与性能关系等基本物理化学问题，需要表面结构明确的微/纳米晶体。本项目拟以具有催化等重要应用背景的功能微/纳米晶体的表面结构的控制为主要目标，通过相关原位技术结合理论模拟，系统地从晶体生长动力学和热力学两个方面考察微/纳米晶体表面结构的控制和形成机制，提出微/纳米晶体表面结构控制的方法和理论；制备组成确定、表面结构可控的贵金属和氧化物微/纳米晶体，结合电化学、光谱、程序升温脱附质谱以及EXAFS等多种结构表征手段，探索微/纳米晶体的表面结构研究方法，确定微/纳米晶体的表面结构；从原子、分子结构水平深入研究复杂实际体系中固体表面结构与相关物理化学性质的内在关联；为催化等复杂实际体系中相关材料的设计和应用提供理论指导。毋庸置疑，该研究将可能推动固体与表面物理化学研究迈上新的台阶。

在过去的几十年里，表面化学家在单晶表面的物理化学行为和性质等方面取得了许多引人瞩目的成果，但基于单晶的表面化学研究成果很难直接应用到实用体系中。以表界面结构明确的微/纳米晶体可控制备为目标，深入探讨实际体系中固体表面的结构与性能关系是表面化学领域研究前沿，也极具挑战。针对这一前沿科学问题，本项目旨在研究微/纳米晶体表界面结构控制方法和理论、构效关系。相关研究取得了系列重要进展：1）以热力学定律为基础，从理论的源头推导出裸露晶面的表面能与晶体生长过程的过饱和度成正比；结合二维成核相关理论，发现在极高的过饱和度的条件下，晶体的生长趋于各向同性；该理论可为合理设计合成具有不同表面结构的微/纳米晶给予有效指导；提出了两种金属的平衡电化学势差是种子法生长过程中决定双金属纳米异质结构形成时是否发生对称性破缺的热力学本质原因；2）构筑了系列金属（合金）片状内凹多面体结构、高能面裸露的五重孪晶的金属纳米晶、高能面裸露的金属氧化物纳米晶以及其他具有特殊表界面结构的纳米结构材料，探讨了相关纳米晶的形成机理及构效关系；3）结合先进表征手段和理论计算，在分子层次对复杂界面结构进行了细致的分析和探讨，深入理解了金属-有机、金属-无机氧化物等复杂界面在催化反应中的作用机制；4）以金属纳米团簇为模型，合成了系列金属纳米团簇并进行了全结构表征，为纳米晶表界面精细结构的表征提供了新的思路与策略。执行期间，共发表基金标注SCI论文102篇，其中包括Science 2篇、 Nature Mater. 1篇、 Nature Commun. 5篇、JACS 15篇、Angew. Chem. 5篇。因相关工作的系统性，分别应邀为Acc. Chem. Res.、Chem. Soc. Rev.等刊物撰写了综述和进展报告，项目负责人在第7届全国结构化学会议上做大会报告等。