Chemical Insights into the Formation of Colloidal High Entropy Alloy Nanoparticles
Chemical Insights into the Formation of Colloidal High Entropy Alloy Nanoparticles
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DOI：
10.1021/acsnano.3c00176
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发表时间：
2023-03-09
期刊：
影响因子：
17.1
通讯作者：
Schaak, Raymond E.
中科院分区：
文献类型：
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作者：
Dey, Gaurav R.;McCormick, Connor R.;Schaak, Raymond E.
高熵合金（HEAs）的纳米颗粒具有独特的性质，这是由于它们的高表面积与体积比以及它们的五种或更多种组成元素之间的协同相互作用，这些组成元素随机分布在整个晶格中。合成HEA纳米颗粒的方法正在出现，包括产生胶体产物的溶液方法。然而，HEA纳米颗粒的复杂的多元素组成使得识别和理解它们的反应化学和它们形成的途径具有挑战性，这阻碍了它们的合理合成。在这里，我们展示了合成和阐明7胶体HEA纳米粒子系统，包含各种组合的贵金属（Pd，Pt，Rh，Ir），3D过渡金属（Ni，Fe，Co），和一个p-块元素（Sn）的反应途径。通过在275摄氏度下将含有所有五种组分金属盐的溶液缓慢注入油胺和十八烯中来合成纳米颗粒。使用NiPdPtRhIr作为铅系统，我们证实了所有五种元素的均匀共定位，并通过改变它们的比例实现可调组合物。我们还在NiPdPtRhIr样本的亚群中观察到了异质性，包括富含钯的区域。在早期时间点停止反应并表征分离的产物揭示了从富Pd NiPd晶种到最终NiPdPtRhIr HEA的时间依赖性组成演变。类似的反应适用于FePdPtRhIr，CoPdPtRhIr，NiFePdPtIr，和NiFeCoPdPt，与修改后的条件，以最有效地将所有五种元素纳入每个HEA，也揭示了类似的富Pd种子与系统依赖性的差异，在纳米粒子的元素吸收的速率和顺序。当移动到SnPdPtRhIr和NiSnPdPtIr，时间依赖性的形成途径是更一致的同时coreduction，而不是通过形成反应性种子。这些研究揭示了使用相同合成方法形成不同胶体HEA纳米颗粒的途径之间的重要相似性和差异，并建立了通用性。这些结果为将一系列不同的元素纳入HEA纳米颗粒提供了指导，最终提供了有关如何定义和优化合成方案的基础知识，扩展到不同的HEA纳米颗粒系统，并实现高相纯度。
Nanoparticles of high entropy alloys (HEAs) have distinct properties that result from their high surface-to volume ratios coupled with synergistic interactions among their five or more constituent elements, which are randomly distributed throughout a crystalline lattice. Methods to synthesize HEA nanoparticles are emerging, including solution approaches that yield colloidal products. However, the complex multielement compositions of HEA nanoparticles make it challenging to identify and understand their reaction chemistry and the pathways by which they form, which hinders their rational synthesis. Here, we demonstrate the synthesis and elucidate the reaction pathways of seven colloidal HEA nanoparticle systems that contain various combinations of noble metals (Pd, Pt, Rh, Ir), 3d transition metals (Ni, Fe, Co), and a p-block element (Sn). The nanoparticles were synthesized by slowly injecting a solution containing all five constituent metal salts into oleylamine and octadecene at 275 degrees C. Using NiPdPtRhIr as a lead system, we confirmed the homogeneous colocalization of all five elements and achieved tunable compositions by varying their ratios. We also observed heterogeneities, including Pd-rich regions, in a subpopulation of the NiPdPtRhIr sample. Halting the reaction at early time points and characterizing the isolated products revealed a time dependent composition evolution from Pd-rich NiPd seeds to the final NiPdPtRhIr HEA. Similar reactions applied to FePdPtRhIr, CoPdPtRhIr, NiFePdPtIr, and NiFeCoPdPt, with modified conditions to most efficiently incorporate all five elements into each HEA, also revealed similar Pd-rich seeds with system-dependent differences in the rates and sequences of element uptake into the nanoparticles. When moving to SnPdPtRhIr and NiSnPdPtIr, the time-dependent formation pathway was more consistent with simultaneous coreduction rather than through formation of reactive seeds. These studies reveal important similarities and differences among the pathways by which different colloidal HEA nanoparticles form using the same synthetic method, as well as establish generality. The results provide guidelines for incorporating a range of different elements into HEA nanoparticles, ultimately providing fundamental knowledge about how to define and optimize synthetic protocols, expand into different HEA nanoparticle systems, and achieve high phase purity.