Controlling Reactivity in Metal/Metal Oxide Nanoparticles

纳米粒子(NPs)是各种高风险应用的关键材料，这些应用将应对医疗保健(再生医学和癌症治疗)、信息技术(数据存储)、催化和环境修复(污染物/细菌去除)方面的全球挑战。虽然在这些领域取得了重大进展，但关键挑战依然存在。在热疗和药物输送等医疗应用中，高磁矩NP核容易被氧化降解，从而降低其有效性。同样，用于机动车尾气系统的催化NPs也会经历快速的在线失活，据估计，这会消耗超过必要数量50倍以上的铂。反应性显然是这些问题的核心，需要更好地在原子尺度上了解核粒子在不同的气体和水环境中如何反应，特别是在纳米级氧化方面(例如，见Pratt、Kröger等人，《自然材料》，2014)。该项目旨在通过将一种新的、独特的纳米颗粒生长设备与最先进的表征技术相结合来提供这种理解。具体地说，将研究氧化过程中晶界和间隙扩散之间的平衡，以及如何通过工程上的NP尺寸、形状、涂层材料和应变来调整平衡。更多地了解这些机制将有利于上述具有重大科学和商业影响的国家应用。首先，将使用一种新的气体聚集簇源来合成NP，这种源可以非常仔细地控制NP的性质，如大小、尺寸分布、核和壳的组成以及几何形状。然后，该项目将涉及使用各种尖端表征技术来监测反应性：经过象差校正的原位流体细胞电子显微镜将提供孤立粒子和溶液中粒子的高分辨率图像，以便我们能够监测NP结构的变化；将使用独特的超高真空(UHV)表面分析设备来探测天然、核壳和功能化NPs的电子和磁性性质；还将考虑关于磁性的理论投入以及晶界/缺陷的作用。

Nanoparticles (NPs)-clusters of atoms no larger than 100 nm in any dimension-are critical materials for a variety of high-stake applications that will address global challenges in healthcare (regenerative medicine and cancer therapy), nformation technologies (data storage), catalysis, and environmental remediation (contaminant/bacteria removal). Whilst significant progress in these areas has been made, key challenges remain. In medical applications such as hyperthermia and drug delivery, high-magnetic-moment NP cores are prone to oxidative degradation, which reduces their effectiveness. Similarly, catalytic NPs used in motor vehicle exhaust systems undergo rapid on-stream deactivation which is estimated to consume more than 50 times more platinum than necessary. Reactivity is clearly at the heart of these issues and a better atomic-scale understanding of how NPs react in different gaseous and aqueous environments, particularly with regard to nanoscale oxidation, is required (see, for example, Pratt, Kröger et al., Nature Materials, 2014). This project aims to provide this understanding by combining a new, unique nanoparticle growth facility with state-of-the-art characterisation techniques. Specifically, the balance between grain-boundary and interstitial diffusion during oxidation and how this can be tailored by engineering NP size, shape, coating material and strain will be investigated. More insight on these mechanisms will benefit the above NP applications with potential for significant scientific and commercial impact. Initially, NPs will be synthesised using a new gas-aggregation cluster source which affords very careful control of NP properties such as size, size distribution, core and shell composition, and geometry. The project will then involve the use of a variety of cutting-edge characterisation techniques to monitor reactivity: aberration-corrected and in situ fluid cell electron microscopy will provide high resolution images of isolated and in-solution particles so that we can monitor changes in NP structure; a unique ultrahigh vacuum (UHV) surface analysis facility will be used to probe the electronic and magnetic properties of native, core-shell and functionalized NPs; theoretical input on magnetic properties and the role of grain boundaries/defects will also be considered.