Department of Chemical Sciences, University of Padova, via Marzolo 1, I-35131 Padova, Italy.
Department of Molecular Sciences and Nanosystems, Università Ca' Foscari Venezia, via Torino 155/b, I-30172 Venezia-Mestre, Italy.
J Colloid Interface Sci. 2017 Mar 1;489:18-27. doi: 10.1016/j.jcis.2016.10.023. Epub 2016 Oct 13.
Laser ablation in liquids (LAL) emerged as a powerful technique for the synthesis of multielement nanoparticles (NPs) such as metal alloys with thermodynamically forbidden composition. Consequently, there is a great interest in expanding the current knowledge about NPs formation during LAL, in order to improve the control on product structure and to extend the range of compositions accessible by this technique. Here we performed a systematic investigation on alloy NPs formation by nanosecond LAL of Au/Fe/glass multilayers with different thickness and order of deposition. The experiments were carried out in ethanol and water, which have, respectively, favourable and unfavourable effects on alloy formation. Results were analyzed with optical absorption spectroscopy, transmission electron microscopy and Mie theory for simple and core-shell spheres. Since alloy NPs were obtained in all cases, our findings provide the evidence that the two metals are mixed during particles formation. Besides, our results suggest that the probability of interaction between ablated matter and solution species is higher for the topmost layer of the target, i.e. the one closer to the solid/liquid interface. This provides useful insight for the synthesis of nanoalloys with new compositions, that are of interest in several fields, from catalysis to photonics and nanomedicine.
激光烧蚀液体（LAL）技术已经成为一种强大的方法，可用于合成多元素纳米粒子（NPs），如热力学上禁止的组成的金属合金。因此，人们对扩展关于 LAL 期间 NPs 形成的现有知识非常感兴趣，以提高对产品结构的控制能力，并扩展该技术可获得的组成范围。在这里，我们通过使用不同厚度和沉积顺序的 Au/Fe/玻璃多层膜进行纳秒 LAL，对合金 NPs 的形成进行了系统的研究。实验分别在乙醇和水中进行，这两种溶剂对合金形成分别具有有利和不利的影响。结果通过光学吸收光谱、透射电子显微镜和 Mie 理论对简单和核壳球体进行了分析。由于在所有情况下都获得了合金 NPs，因此我们的研究结果提供了证据，表明在颗粒形成过程中两种金属会混合。此外，我们的结果表明，与溶液物种相互作用的可能性对于靶材的最顶层（即更接近固/液界面的那一层）更高。这为合成具有新组成的纳米合金提供了有用的见解，这些纳米合金在催化、光子学和纳米医学等多个领域都具有重要意义。
