Method Development for the Synthesis of Colloidal Multimetallic Nanocrystals

胶体金属纳米晶体（NCs）是一种独特的材料，具有吸引人的物理化学性质，是开发太阳能收集、电催化或生物医学等新型绿色技术的研究热点。然而，金属nc的实际实施仍然存在一些重大问题，例如，贵金属的高成本或Co， Ni或Fe等金属的化学稳定性。人们已经做出了巨大的努力来解决这些缺点，多金属纳米材料的合成（MM NC）是最有前途的策略之一。这一事实可以通过MM nc显示的增强的化学稳定性和改进的电学、光学、磁性和催化性能（同时减少贵金属负载）来解释。胶体化学方法提供了对双金属贵金属基MM nc尺寸和形状的无与伦比的控制。不幸的是，由于不同金属之间的氧化还原电势差异很大，通常会影响它们的共结晶，因此用胶体方法合成非贵重MM nc仍然具有挑战性。实际上，含有几种不同贵金属和非贵金属的MM nc通常是通过基于高温的方法合成的。然而，这些方法通常对NC的尺寸分散性控制较低，因为它们强烈依赖于使用支撑来避免NC合并。在这个DFG提案中，我们的目标是开发一种先进的方法来合成具有可调谐尺寸，形貌，组成和金属原子混合的胶体MM纳米。所提出的策略的基础依赖于将胶体方法提供低尺寸分散性nc的能力与高温方法生产MM nc的能力相结合。因此，设想的方法植根于过去二十年中为合成具有不同尺寸和形态的高质量金属纳米材料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纳米颗粒组装成MM超颗粒（即由较小颗粒组成的颗粒），这将作为目标MM纳米颗粒形成的平台。然后，超快脉冲激光将用于通过激光诱导熔融组装的超粒子形成MM nc。所提出的策略最终将提供各种不同尺寸、成分和金属原子混合模式的胶体MM nc的合成途径。

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.