Two-dimensional materials and surfactants: exfoliation, controlled stacks, targeted particle growth and functional heterostructures

许多应用需要单分散的二维纳米晶体（2DNC）。形状和大小决定了它们的光电特性，例如，由于量子限制在横向尺寸以及层数上，边缘结构在材料特性（金属，半导体）及其催化活性上有所不同。因此，控制2DNC的尺寸和边缘对于光电和光催化应用是必要的。我们的目标是通过添加表面活性剂来控制2DNC沿特定边缘的生长，这些表面活性剂可以钝化或激活与胶体溶液单体的反应，从而控制2DNC的层数（从单层到堆叠）、横向尺寸、层间距离和横向形状。我们将研究如何攻击2DNC纳米片的基面以产生环形结构，并探索是否有可能指导合成特定的多型。我们将研究用表面活性剂填充2DNC单层膜的可能性，以保持2DNC单层膜的电子特性。此外，我们将研究表面活性剂与2DNC的电子相互作用，特别是与自由基表面活性剂和电荷阱或电荷储层的电子相互作用。我们的研究基于第一性原理计算，将与两个领先的实验小组密切合作，他们将提供原位光谱数据，创建2DNC和合适的表面活性剂。最初的目标材料是金属硫族化合物（TMC），从第4族和第6族过渡金属二硫族化合物（TMDC）开始，后来扩展到贵金属二硫族化合物（第10族）和2D COFs （2D聚合物）。最初，表面活性剂作为层分离的手段，但在项目结束时，我们将探索如何利用表面活性剂功能化作为控制2DNC功能的手段。在这个项目中执行的方法实现，即一个多高级/低级方法和一个自动方案来计算电荷载流子的迁移率，将通过github公开提供，但也包括在阿姆斯特丹密度功能软件包的图形用户界面中。我们与BAND代码的主要开发人员密切合作，该代码支持具有明确的0D-3D边界条件的DFT计算。

Many applications require monodisperse 2D nanocrystals (2DNC). Shape and size determine, e.g., their optoelectronic properties due to quantum confinement in lateral dimensions as well as in the number of layers, and edge structures differ in material character (metallic, semiconducting) and its catalytic activity. Thus, control of size and edges of the 2DNC is necessary for optoelectronic and photocatalytic applications. We aim at controlling 2DNC growth along specific edges by adding surfactants which either passivate or activate reactions with monomers of the colloidal solution, thus controlling the number of layers (from monolayers to stacks), the lateral size, interlayer distance, and the lateral shape of the 2DNC. We will investigate how to attack the basal plane of 2DNC nanodiscs in order to produce toroidal structures, and explore if it is possible to guide synthesis towards specific polytypes. We will investigate the possibility to stack 2DNC monolayers intercalated with surfactants in such way that the electronic properties of the 2DNC monolayers are maintained. Further, we will study electronic interactions of surfactants with 2DNC, in particular with radical surfactants and with charge traps or charge reservoirs.Our research, based on first-principles calculations, will be carried out in close collaboration with two leading experimental groups who will provide in situ spectroscopic data, create 2DNC and suitable surfactants. Initial target materials are metal chalcogenides (TMC), starting from Group 4 and Group 6 transition metal dichalcogenides (TMDC), later extending to noble metal dichalcogenides (Group 10), and 2D COFs (2D polymers). Initially, surfactants serve as means for layer separation, but at the end of the project, we will explore how surfactant functionalization can be exploited as means for control of functionality of the 2DNC. Method implementations carried out in this project, i.e. a multi high-level/low-level method and an automated scheme to compute charge carrier mobilities, will be made publicly available via github, but also be included in the graphical user interface of the Amsterdam Density Functional software package. We collaborate closely with the main developer of the BAND code, which supports DFT calculations with explicit 0D-3D boundary conditions.