Core-Shell nanoparticle models for in-situ SERS measurements of carbonate dissolution under environmentally realistic conditions

用于在现实环境条件下原位 SERS 测量碳酸盐溶解的核壳纳米粒子模型

• 批准号: NE/I019514/1
• 负责人: Philip Davies
• 金额: $ 9.47万
• 依托单位: CARDIFF UNIVERSITY
• 依托单位国家: 英国
• 项目类别: Training Grant
• 财政年份: 2011
• 资助国家: 英国
• 起止时间: 2011 至 无数据
• 项目状态: 已结题
• 来源: https://gtr.ukri.org/projects?ref=NE%2FI019514%2F1
• 关键词: Core; Shell; nanoparticle; models; situ

Our aim is to develop an in-situ analytical probe of dissolution processes that can address, at a molecular level, the mechanistic questions raised by uncertainties in the rates of biogenic carbonate dissolution. Surface enhanced Raman spectroscopy (SERS) will be used to monitor the behaviour of carbonate shells grown on custom made gold nanoparticles ('Core-Shell' structures). By manipulating the structure and habit of the carbonate in these systems we will explore the individual effects of chemical composition, mineral structure and lattice imperfection on carbonate solubility with an in-situ, molecularly specific probe. The particular issue we are addressing is that of the dissolution of marine carbonates, which represents a fundamental component of the global carbon cycle. The production of biogenic carbonate in the surface ocean greatly outweighs the supply of its ingredients from rivers and without dissolution of much of this carbonate prior to its burial at the seafloor, the system could not sustain itself. However, anthropogenic emission of CO2 leading to ocean acidification (OA), is effectively lowering the saturation state of the oceans with respect to carbonate and raising considerable concerns regarding the future carbon balance in the oceans. Despite decades of study there remains great uncertainty concerning some of the most fundamental aspects of carbonate dissolution: even the rate order for carbonate dissolution has an uncertainty factor of 4. Furthermore, the partial dissolution of carbonate shells is empirically known to affect their chemical composition, which itself is often used to proxy ancient oceanic conditions. The current uncertainty as to how dissolution precisely affects composition presents critical limitations on the applicability of these tools. Many of these uncertainties have arisen from the complexity (in mineralogy and form) of 'typical' biogenic carbonates (e.g. foraminifera and coccoliths, that comprise most of the global production of marine carbonates). The proposed studentship aims to develop core-shell nanoparticle SERS as an analytical technique capable of providing mechanistic surface information under realistic conditions. Nanoparticle core-shell synthesis techniques for carbonates will be developed and rates of dissolution determined and compared against bulk rates and shell thickness measurements from TEM (FENAC) and XPS. Raman can distinguish between all the different structural polymorphs of calcium carbonates and thus will enable the project to progress to an investigation of the different carbonate structures. Specific gold core shapes (spheres, rods, cubes etc) will be synthesised to investigate the role of structural stress on the carbonate shell structure, growth habit and subsequent dissolution. The project will lay the ground work for the development of a high pressure system which will be the subject of a future application. The project offers a unique opportunity for a PhD student to gain extensive training in nanoscience techniques and nanoscale synthesis combined with experience in the field of analytical chemistry applied to environmental problems.

我们的目标是开发一种原位分析探头的溶解过程，可以解决，在分子水平上，生物碳酸盐溶解速率的不确定性所提出的机械问题。表面增强拉曼光谱（Sers）将被用来监测碳酸盐壳生长在定制的金纳米粒子（“核-壳”结构）的行为。通过操纵这些系统中的碳酸盐的结构和习性，我们将探索化学组成，矿物结构和晶格缺陷对碳酸盐溶解度的影响，并使用原位分子特异性探针。我们正在处理的具体问题是海洋碳酸盐的溶解问题，这是全球碳循环的一个基本组成部分。表层海洋中生物成因的碳酸盐的产量大大超过了河流对其成分的供应，如果这些碳酸盐在埋藏在海底之前没有大部分溶解，该系统就无法维持自身。然而，导致海洋酸化（OA）的人为CO2排放正在有效降低海洋碳酸盐饱和状态，并引起人们对海洋未来碳平衡的严重关切。尽管经过了几十年的研究，碳酸盐溶解的一些最基本的方面仍然存在很大的不确定性：甚至碳酸盐溶解的速率顺序也有4的不确定性因子。此外，根据经验，碳酸盐贝壳的部分溶解会影响其化学成分，而化学成分本身通常被用来代表古代海洋条件。目前的不确定性，如何溶解精确地影响组成提出了这些工具的适用性的关键限制。其中许多不确定性是由于“典型的”生物成因碳酸盐（例如，有孔虫和球化石，它们构成了全球海洋碳酸盐的大部分产量）的复杂性（在矿物学和形式上）造成的。拟议的学生奖学金旨在开发核壳纳米Sers作为一种分析技术，能够在现实条件下提供机械表面信息。将开发用于碳酸盐的纳米颗粒核-壳合成技术，并确定溶解速率，并将其与TEM（FENAC）和XPS的体积速率和壳厚度测量值进行比较。拉曼可以区分碳酸钙的所有不同结构多晶型物，从而使该项目能够进展到对不同碳酸盐结构的研究。将合成特定的金核形状（球形，棒状，立方体等），以研究结构应力对碳酸盐壳结构，生长习性和随后溶解的作用。该项目将为高压系统的开发奠定基础，该系统将成为未来应用的主题。该项目为博士生提供了一个独特的机会，以获得在纳米科学技术和纳米级合成与应用于环境问题的分析化学领域的经验相结合的广泛培训。