“活性气体与金属原子”复合团簇气相自组装合成无支撑原子级厚度活泼金属纳米片

Accompanying the booming development of two-dimensional (2D) materials, the freestanding ultrathin metallic nanosheets (FUMNSs) have attracted considerable attention due to their potential applications in catalysis, biomedicine, magnetic recording, and etc. However, the fabrication of stable FUMNSs is difficult arising from the non-directional metallic bonds in metals, thus leading to no driving force for the anisotropic growth of 2D structure. At present, the developed strategies towards FUMNSs are mainly solution based chemical methods and the synthesized material categories are limited to noble metals and their alloys. For the active metals, the ultrathin 2D structure is rather hard to achieve through chemical strategy because of their high electrode potential, and the investigations are just in infancy. Based on our primary experimental and theoretical results, we suggest a new hypothesis on the synthesis of freestanding ultrathin active metal nanosheets (FUAMNSs), which involves the self-assembly of the “active gas-metal atoms” complex clusters into atomically thin 2D structures in gas phase. In this project, theoretical and experimental attempts will be made to testify this hypothesis. Through theoretical calculations, we will find out the suitable active gas, display the configuration of the complex clusters, and exhibit the self-assembly rule of the complex clusters. Then, we will systematically investigate the formation and diffusion of complex clusters in gaseous synthesis, and finally achieve FUAMNSs with thickness less than 2 nm. This project will make a breakthrough in the controlled synthesis of FUAMNSs, and lay the foundation for the investigation of the properties and applications of FUAMNSs.

在二维材料研究推动下，无支撑超薄金属纳米片受到广泛关注，在工业催化、生物医学和磁记录等领域具有广阔的应用前景。但是由于金属键没有方向性，缺乏二维各向异性生长的驱动力，很难形成稳定的超薄二维结构。目前无支撑超薄金属纳米片的合成主要是化学法，材料种类集中在贵金属及其合金。对于活泼金属，由于还原电势较高，化学合成超薄结构非常困难，研究还处于起步阶段。本项目基于前期实验和计算结果，提出“活性气体与金属原子”复合团簇气相自组装合成无支撑超薄活泼金属纳米片的新机制。本项目将围绕这个机制，通过理论计算阐明活性气体种类、“活性气体与金属原子”复合团簇空间构型及自组装规律对超薄二维结构的调控作用；设计实验研究气相环境中复合团簇形成及扩散对超薄纳米片生长的影响，合成具有原子级厚度（小于2nm）的超薄活泼金属纳米片。本项目将突破超薄活泼金属纳米片制备的瓶颈，为超薄活泼金属纳米片的性能及应用研究奠定基础。

本项目按照研究计划阐明了“活性气体与金属原子”复合团簇气相自组装的生长机制，可控合成具有原子级厚度的超薄活泼金属纳米片、金属/硫化物复合纳米片，并研究了其在光催化制氢、电化学还原CO2等领域的应用。在本项目进行过程中，我们发现在气相环境下，金属原子团簇可以与金属原子发生交换作用，合成一系列具有高活性的金属氧化物与金属/氧化物催化剂。本项目发表SCI论文16篇，申请发明专利1项。主要成果概述如下：.二维超薄纳米材料因其原子级的厚度和二维平面结构的特点往往具有不同于块材的电子结构，从而会显著改变材料的性能，因此在信息、能源与环境等多个领域具有广阔的应用前景。本项目利用实验与理论计算解释，足量的活性气体与气相中金属原子团簇形成平面构型，避免金属原子自发形成三维构型团簇继而同向生长是形成超薄活泼金属纳米片的关键。本项目合成了超薄Cd纳米片，在Cd纳米片表面生长了1 nm厚的CdS超薄纳米片该CdS超薄纳米片具有非常优异的光催化产氢性能，在不添加任何助催化剂的产氢效率高达30 mmol/h/g。本项目还合成了超薄Zn/ZnS复合纳米片并应用于电化学还原CO2，CO产生率保持在90%以上。