Colloidal High Entropy Alloy (HEA) Nanoparticles by kinetically controlled Laser Ablation Synthesis in Liquids- Formation mechanism and their integration into Biphasic Core-Shell Morphologies

液体形成机制中通过动力学控制激光烧蚀合成胶体高熵合金（HEA）纳米颗粒及其与双相核壳形态的整合

• 批准号: 277627168
• 负责人: Professor Dr.-Ing. Stephan Barcikowski
• 金额: --
• 依托单位: Lehrstuhl für Technische Chemie I
• 依托单位国家: 德国
• 项目类别: Research Grants
• 资助国家: 德国
• 项目状态: 未结题
• 来源: https://gepris.dfg.de/gepris/projekt/277627168?language=en
• 关键词: Colloidal; Entropy; Alloy; HEA; Nanoparticles

High entropy alloys (HEA) nanoparticles (NP) are an emerging scientific field of particular interest in heterogeneous catalysis. They are characterized by elemental complexity with at least five elements at near equal compositions and still possess a surprisingly simple solid solution crystal structure. Laser ablation in liquids (LAL) is a promising method for the synthesis of HEA NP as it is scalable to the g/h range and provides the particles as colloids without the need for organic surface ligands or support materials. However, the formation mechanism of solid solution HEA NP by LAL is up to date insufficiently understood. Furthermore, the compositional range (atomic ratios) for fully mixed HEA NP synthesized by this technique has not been systematically examined.In previous experiments (1st phase of this project) we already explored related scientific questions for bimetallic systems with an emphasis on FeAu. We found that the prevalence of the formation of ideally mixed solid solution particles over segregated structures is critically driven by the composition of the target, the particle size, and the laser pulse duration. This was complemented by the identification of a unique and complex segregated Fe@AuFe core-shell structure, which probably emerges due to a high mismatch in surface energy and melting point in the contained elements. In this project, we aim to elucidate whether these findings are transferable to HEA NP. Thereto NP from I) CoCrFeMnNi II) AgAuCuPdPt will be synthesized by LAL and process parameters like laser pulse duration will be adapted to yield solid solution HEA structures with homogeneous elemental distribution and minimized oxidation. In a consecutive step, we will investigate whether and to what extent the excess of specifically chosen elements in the HEA NP, e.g. Ag and Pt in alloy II), would drive the particles into elemental segregation, whether a core-shell structure would form, and particularly how these transitions depend on NP size. These examinations necessitate the utilization and development of highly advanced STEM/EDX- and SAED-based methods, which allow differentiation of multiple elements and crystal structures within a single NP at atomic resolution. In another approach, we will closely examine structural and compositional mismatches between the surface and the bulk of HEA NP using STEM/EDX and EELS as well as cyclic voltammetry and XPS, particularly relevant as surface composition drives potential applicability in catalysis. Finally, an examination of changes in composition and phase structure in laser-fabricated HEA NP will be conducted by in situ TEM heating experiments. Here we will explore the potential metastability of the HEA NP and based on this elucidate the transformation mechanism towards thermodynamic equilibrium. These studies will be complemented by computational modeling using Molecular Dynamics and Monte Carlo simulations.

高熵合金（HEA）纳米颗粒（NP）是一个在异质催化中特别感兴趣的新兴科学领域。它们的特征是元素复杂性，至少五个元素在接近相等的组成处，并且仍然具有令人惊讶的简单实心溶液晶体结构。液体中的激光消融（LAL）是合成HEAP的一种有前途的方法，因为它可扩展到G/H范围，并提供颗粒作为胶体，而无需有机表面配体或支撑材料。但是，LAL的固体解决方案HEA的形成机制是最新的。此外，尚未系统地检查由该技术合成的完全混合HEA NP的组成范围（原子比）。在先前的实验（该项目的第一阶段）中，我们已经探索了双金属系统的相关科学问题，并重点介绍了Feau。我们发现，理想的混合固体溶液颗粒在隔离结构上的形成率由目标的组成，粒径和激光脉冲持续时间严重驱动。这是通过识别独特而复杂的隔离fe@aufe核壳结构来补充的，该结构可能是由于表面能量高的表面能量不匹配和所包含元素中的熔点而出现的。在这个项目中，我们旨在阐明这些发现是否可以转移到HEA NP。 i）cocrfemnni ii）agaucupdpt将由lal合成，而过程参数（如激光脉冲持续时间）将适应具有均匀元素分布并最小化氧化的实心溶液沉积结构。在连续的一步中，我们将调查是否以及在何种程度上以及在何种程度上，例如在HEA NP中的特定元素，例如合金II）中的Ag和Pt会将颗粒驱动到元素分离中，是否形成核心壳结构，尤其是这些过渡如何取决于NP的大小。这些检查需要对基于高级的茎/EDX和基于SAED的方法的利用和开发，这可以在原子分辨率下单个NP内的多个元素和晶体结构进行区分。在另一种方法中，我们将使用STEM/EDX和EEL以及循环伏安法和XPS仔细检查表面和大部分HEAP之间的结构和组成不匹配，特别是与表面组成相关，这促进了促进催化中的潜在适用性。最后，将通过原位加热实验进行对激光制造的HEAP中组成和相结构的变化的检查。在这里，我们将探讨HEA NP的潜在亚竞争力，并基于此阐明了对热力学平衡的转化机制。这些研究将通过使用分子动力学和蒙特卡洛模拟的计算建模来补充。