二维材料封装金属的电子传递机制及催化调控效应的第一性原理研究

Recent years, two-dimensionally (2-D) layered materials encapsulating metal nanoparticles emerge as a novel catalyst structure capable of catalyzing a variety of reactions with unique activity, selectivity, and stability under harsh reaction conditions. The structure is featured by the highly stable 2-D layered material and the confined non-noble metal nanoparticles which can tune the activity of the covering layers, and thus it is called the robust ‘chainmail’ catalyst and is considered as a promising substitute for the precious noble-metal catalyst. It has been well-studied that the active sites of ‘chainmail’ catalyst are located on the outer surface of the structure and the activity is induced by the transfer of electrons from the encapsulated metal cores to the 2-D layers through the electronic interaction between them. Though the eminent development of ‘chainmail’ catalyst that has been made, there still lacks an atomic-level understanding of the following aspects: (1) the electron transfer mechanism and the factors that affect it; (2) the dependence of the electron transfer mechanism on the 2-D materials and metal cores and its effect on tuning the catalytic activity and reaction mechanism of the catalyst; (3) the viability of using ‘chainmail’ catalyst as a support for tuning the activity of other materials. In this project, we will adopt computational chemistry tools to build a series of models of 2-D material encapsulating metal nanoparticles and their derivative structures, to perform systematic study of the material from those aspects using density functional theory calculations. Our objective is to dig more into the chemical nature of ‘chainmail’ catalyst and provide theoretical guiding for the development of novel ‘chainmail’ catalyst.

二维材料封装金属纳米粒子是近年来迅速发展起来的贵金属替代催化剂。基于二维材料的高稳定性以及封装于其中的非贵金属纳米粒子的活性调控作用，该催化剂应用于苛刻化学反应条件下的催化反应时表现出独特的活性及稳定性，因而被称为“铠甲催化剂”。研究表明该催化剂的活性位是处于外层的二维材料表面，活性来源于被封装的金属纳米粒子对表层电子结构的调控以及由金属向表层的电子传递效应。“铠甲催化”概念在催化研究领域已取得显著成果。然而，在原子层面上对此类结构中的电子传递机制、影响电子传递的因素，及两者对二维材料和金属材料种类和属性的依赖性、对催化活性和反应机理影响，以及“铠甲催化剂”自身能否作为载体来诱导和调控其他材料的催化活性，尚缺乏深入认识与理解。本项目拟采用第一性原理方法，构建一系列“铠甲催化剂”及其衍生结构，对上述问题展开系统研究，为进一步挖掘“铠甲催化”的应用潜力并促进新型“铠甲催化剂”的设计与开发提供理论指导。

“铠甲催化”是项目负责人与实验合作者原创提出的催化新概念。基于二维材料高的结构稳定性以及包裹于其中的非贵金属纳米粒子的活性调控作用，该催化剂应用于苛刻的化学环境中的催化反应时表现出独特的活性及稳定性，因而被称为“铠甲催化剂”。研究表明该催化剂的活性位是处于外层的二维材料表面，活性来源于包裹的金属粒子对其电子结构的调控以及由金属向表层的电子传递效应。“铠甲催化”概念在催化研究领域已取得显著成果。然而，在原子层面上对此类结构中的电子传递机制、影响电子传递的因素，及两者对二维材料和金属材料种类和属性的依赖性、对催化活性和反应机理影响，以及“铠甲催化剂”自身能否作为载体来诱导和调控其他材料的催化活性，尚缺乏深入认识与理解。本项目拟采用第一性原理方法，构建一系列“铠甲催化剂”及其衍生结构，对上述问题展开系统研究，为进一步挖掘“铠甲催化”的应用潜力并促进新型“铠甲催化剂”的设计与开发提供理论指导。项目执行期间，项目负责人以（共同）通讯或第一作者发表SCI论文5篇，包括Angew. Chem. Int. Ed.（2篇）、Nano Energy（2篇）、J. Mater. Chem. A（1篇）。入选2020年“兴辽英才计划”青年拔尖人才项目。主要成果如下：（1）提出MoS2/石墨烯封装金属“双层铠甲”中的电子穿透和调控效应，提升了MoS2边结构的催化活性并拓展了“铠甲催化”概念；（2）提出决定铠甲催化活性的两个关键因素，即内核金属向碳层的电子转移数和碳层的曲率，建立了催化活性与两种因素的线性关系；（3）提出铠甲催化剂表面对Pt原子的电子限域效应，显著提高了Pt位点的催化HER活性和稳定性；（4）提出二维MoS2晶格限域Rh单原子的短程协同效应，调控并显著提升了MoS2的惰性硫原子的催化活性；（5）揭示二维CoOOH面内晶格限域的高价态Mo单原子可作为活性位点，有效降低OER反应的过电位。