贵金属及其合金热力学亚稳相及五重孪晶纳米晶的形成机理、控制合成及其催化性能研究

贵金属及其合金纳米晶的物理化学性能与其结构密切相关。包括热力学亚稳晶相和五重孪晶结构等在内的贵金属及其合金纳米晶（热力学亚稳结构）常常展现出与热力学最稳定态迥异的性能。但目前对贵金属及其合金纳米晶性能的调控主要集中在热力学最稳定态的尺寸、表面结构、组成上，对于具有热力学亚稳态结构的系统性研究还比较少。本项目拟以控制合成具有热力学亚稳态的贵金属亚稳相及五重孪晶纳米晶为主要研究内容，在研究贵金属纳米晶热力学及动力学生长行为的基础上，厘清热力学亚稳相及五重孪晶的形成机理，实现对具有亚稳态晶相结构、五重孪晶结构纳米晶的可控合成，并系统研究热力学亚稳态贵金属纳米晶与催化性能的构效关系。本项目的实施将加深我们对热力学亚稳态纳米晶微观生长机制的认识，为高性能催化剂的设计提供新的思路。

The physicochemical properties of noble metals and their alloy nanocrystals are greatly related to their structures. Thermodynamically metastable structures, including different crystal phase and cyclic-penta-twinned structure, usually endow nanomaterials with enhanced or new functionalities. However, current researches are mainly focused on tuning sizes, surface structures and compositions of thermodynamically stable noble metal and its alloy nanocrystals. Limited progresses have been achieved on thermodynamically metastable structures. In this proposed project, we will study on controlled syntheses of noble metal and its alloy nanocrystals with thermodynamically metastable crystal phase and cyclic-penta-twinned structure. Based on the studies of growth behaviors from thermodynamical and kinetical aspects, we will try to clarify their intrinsic growth mechanisms, and realize the rationally controlled synthesis of noble metal nanocrystals with thermodynamically metastable crystal phase and cyclic-penta-twinned structure. Moreover, we will study the corresponding catalytic properties of thermodynamically metastable noble metal nanocrystals by taking several typical catalytic reactions as benchmark. We believe that the studies will deepen our understanding of the growth mechanism for thermodynamically metastable noble metal based nanocrystals, and provide guidance in the rational design and synthesis of noble metal based catalytic materials with low cost and high performance.