Method Development for the Synthesis of Colloidal Multimetallic Nanocrystals

胶体金属纳米晶(NCS)是一种独特的材料，具有诱人的物理化学性质，是太阳能集热、电催化或生物医学等新型绿色技术研究的热点。然而，金属NCS的实际实施仍然存在重大问题，例如，与贵金属的高成本或Co、Ni或Fe等金属的化学稳定性有关。人们一直致力于解决这些缺点，合成多金属NC(MM NC)是最有希望的策略之一。这一事实可以用MM纳米管增强的化学稳定性和改善的电、光、磁和催化性能(同时减少贵金属负载量)来解释。在MM纳米管的现有制备路线中，胶体化学方法提供了无与伦比的对双金属贵金属基MM纳米管的尺寸和形状的控制。不幸的是，用胶体方法合成非贵金属MM NCS仍然具有挑战性，因为不同金属之间存在巨大的氧化还原电位差异，这往往会损害它们的共晶。事实上，含有几种不同贵金属和非贵金属的MM NCs通常是通过高温方法合成的。然而，这些方法通常对NCS的尺寸分散性控制较低，因为它们强烈依赖于使用载体来避免NC团聚。在这个DFG方案中，我们旨在开发一种先进的路线来合成尺寸、形貌、组成和金属原子混合可调的胶体MM NCS。该策略的基础是结合胶体方法提供低尺寸分散性NCS的能力和高温方法生产MM NCS的能力。因此，设想的方法植根于过去二十年来为合成不同尺寸和形貌的高质量金属纳米管而开发的大量胶体化学方法。同样，我们将利用现有技术将胶体NCS组装成MM超颗粒(即由较小颗粒组成的颗粒)，作为形成目标MM NCS的平台。然后，超快脉冲激光将被用于通过激光诱导组装的超粒子的熔化过程来形成MM NCS。所提出的策略最终将为合成具有不同尺寸、组成和金属原子混合模式的各种胶体MM纳米管提供途径。

Colloidal metal nanocrystals (NCs) are unique materials with appealing physical-chemical properties which are the focus of intense research for the development of novel and green technologies with implications in solar energy-harvesting, electrocatalysis or biomedicine. Nevertheless, the practical implementation of metal NCs still presents significant issues related, for instance, to the high cost for noble metals or chemical stability of metals such as Co, Ni or Fe. Significant efforts have been dedicated to tackling such drawbacks, being the synthesis of multimetallic NCs (MM NC) one of the most promising strategies. This fact can be explained by the enhanced chemical stability and improved electrical, optical, magnetic and catalytic properties (while reducing noble-metal loading) displayed by MM NCs.Among the available fabrication routes for MM NCs colloidal chemistry methods provide unparalleled control over the size and shape of bimetallic noble-metal-based MM NCs. Unfortunately, the synthesis of non-noble MM NCs by colloidal methods remains challenging because of the large redox potential differences between distinct metals that often impair their co-crystallization. Indeed, MM NCs containing several different noble and non-noble metals are habitually synthesized through high-temperature-based methods. Nevertheless, these approaches typically possess low control over the size dispersity of the NCs, as they strongly depend on the use of supports to avoid the NC coalescence.In this DFG proposal, we aim at the development of an advanced route to synthesize colloidal MM NCs with tuneable size, morphology, composition and metal atom mixing. The fundament of the proposed strategy relies on combining the ability of colloidal methods to provide low size dispersity NCs with that of high-temperature approaches to produce MM NCs. Thereby, the envisaged approach takes roots in the vast amount of colloidal chemistry methods that have been developed in the last two decades for the synthesis of high-quality metal NCs with different dimensions and morphologies. Similarly, we will take advantage of available techniques for the assembly of colloidal NCs into MM supraparticles (i.e., particles composed of smaller particulate), which will serve as platforms for the formation of the targeted MM NCs. Ultrafast pulsed lasers will be then used for the formation of MM NCs through a laser-induced melting process of the assembled supraparticles. The proposed strategy should eventually provide access to the synthesis of a wide variety of colloidal MM NCs with different dimensions, compositions and metal atom mixing patterns.