Method Development for the Synthesis of Colloidal Multimetallic Nanocrystals

胶体金属纳米晶体（nanocrystals，NC）是一种独特的材料，具有独特的物理化学性质，在太阳能收集、电催化、生物医学等领域具有重要的应用价值，是开发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与例如贵金属的高成本或诸如Co、Ni或Fe的金属的化学稳定性相关的重大问题。已经做出了大量努力来解决这些缺点，多金属NC（MM NC）的合成是最有前途的策略之一。这一事实可以解释为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）显示的MM NCs。在可用的制造路线MM NCs胶体化学方法提供无与伦比的控制的大小和形状的贵金属为基础的MM NCs。不幸的是，通过胶体方法合成非贵金属MM NC仍然具有挑战性，因为不同金属之间的氧化还原电位差很大，这通常会损害它们的共结晶。事实上，含有几种不同贵金属和非贵金属的MM NC通常通过基于高温的方法合成。然而，这些方法通常具有较低的控制的尺寸分散性的NC，因为它们强烈依赖于使用的支持，以避免NC coalescence.In这个DFG的建议，我们的目标是在开发一种先进的路线来合成胶体MM NC与可调的大小，形态，组成和金属原子混合。所提出的策略的基础依赖于结合胶体方法的能力，以提供低尺寸分散性的NC与高温方法，以生产MM NC。因此，所设想的方法植根于过去二十年中开发的大量胶体化学方法，用于合成具有不同尺寸和形态的高质量金属NC。类似地，我们将利用可用的技术将胶体NC组装成MM超颗粒（即，由较小颗粒组成的颗粒），其将用作形成靶向MM NC的平台。超快脉冲激光将用于通过组装的超粒子的激光诱导熔化过程形成MM NC。所提出的策略应最终提供各种各样的胶体MM NC与不同的尺寸，组成和金属原子混合模式的合成。

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.