NSF-DFG Echem: Design of Nanostructured Noble - Metal Chalcogenide Electrocatalysts for Hydrogen Evolution Reaction

分子式从MX2到MX(M：Pt或Pd，X：Se或Te)的层状贵金属(Pd，Pt)硫系化合物已被提出作为电化学析氢反应(HER)的活性催化剂，但其催化作用的细节尚不清楚。这可能部分与这些材料中强烈的层间相互作用和尺寸量子化效应有关，这导致它们的电子性质根据层数的不同而发生显著变化。同时，这些物理效应也可能为调整这些材料的催化性能开辟新的途径。此外，在台阶边缘控制设计具有特殊电子性质的配位不足的原子也可能增加高活性催化中心的丰度。在这个项目中，我们将确定这些贵金属硫化物材料的活性组成相，以及如何利用这些贵金属硫化物材料的纳米结构(层数和台阶边缘密度)来提高HER活性。我们还打算利用广泛的过渡金属二卤化物(TMD)的结构相似性作为材料平台来研究TMD相混合物(合金)中可能的协同效应以提高其活性。我们设想，这些材料的平面性质将有助于表征混合相材料的结构和电子性质，从而有助于从根本上理解多组分材料中的协同效应。为了进行这些研究，我们组建了一个具有互补专业知识和能力的团队。平面模型系统将由范德华外延合成，其原子结构和电子性质将由美国南佛罗里达大学Batzill小组的扫描探针显微镜和光电子能谱表征。到目前为止，电化学界对这些定义明确的样品的电化学性质研究很少，这些样品的电化学性质将在Oezaslan小组的TU Braunschweig进行分析。实验确定的微动力学结果将通过从头计算模拟在赫尔姆霍兹中心德累斯顿-罗森多夫的Krasheninnikov小组进行合理化。合金和掺杂剂的理论预测也将指导实验，并有助于确定有希望的材料组合。这个团队对材料进行了详细的表征，以便动力学参数和她的活动可以与它们的物理和化学性质相关联。该项目的成果是发现了新的潜在的HER电催化剂，并通过可控的纳米结构实现了其可调性。这些研究不仅将为先进低维材料的催化作用提供基础知识，还将为先进电催化剂的实际设计开辟新的途径，从而为社会寻找生态能源解决方案做出贡献。

Layered noble metal (Pd, Pt) chalcogenides with structural formulas ranging from MX2 to MX (M: Pt or Pd, and X: Se or Te) have been proposed as active catalysts for the electrochemical hydrogen evolution reaction (HER), but the details of the catalytic action are far from being understood. This may be related in part to strong interlayer interactions and size quantization effects in these materials, which cause significant modifications of their electronic properties depending on the number of layers. At the same time, these physical effects may also open new avenues to the tailoring of catalytic properties in these materials. Moreover, controlled design of undercoordinated atoms at step edges with special electronic properties may also increase the abundance of highly active catalytic sites. In this project, we will identify the active compositional phases and how nano-structuring (number of layers and step edge density) of these noble metal chalcogenide materials may be used to boost the HER activity. We also intend to utilize the structural similarities of a wide range of transition metal dichalcogenides (TMDs) as a materials platform to investigate possible synergetic effects in TMD-phase mixtures (alloys) to enhance HER activity. We envision that the planar nature of these materials will aid the characterization of structural and electronic properties of mixed-phase materials and thus facilitate the fundamental understanding of synergetic effects in multi-component materials. To conduct these studies, we assembled a team with complementary expertise and capabilities. Planar model systems will be synthesized by van der Waals epitaxy, and their atomic structure and electronic properties will be characterized by scanning probe microscopy and photoemission spectroscopy in the Batzill’s group at University of South Florida, USA. The electrochemical properties of these well-defined samples, so far poorly investigated in the electrochemistry community, will be analyzed at the TU Braunschweig in the Oezaslan’s group. The experimentally determined micro-kinetics results will be rationalized through ab initio simulations to be done in Krasheninnikov’s group at the Helmholtz Zentrum Dresden-Rossendorf. The theoretical predictions for alloys and dopants will also guide the experiments and help to identify promising materials combinations. This team encompasses detailed characterization of the materials so that the kinetic parameters and HER activities can be correlated with their physical and chemical properties. The outcome of this project is the identification of new potential electrocatalysts for HER and their tunability by controlled nano-structuring. These studies will not only provide fundamental knowledge on the catalytic action of advanced low-dimensional materials, but also define new pathways for the practical design of advanced electrocatalysts, and thus contribute to finding ecological energy solutions for the society.