贵金属纳米颗粒的超薄氧化物包覆及SERS效应研究

The interaction between the toxic molecules, such as the organic phosphor nerve agents, and noble metal is very weak and it is thus difficult to efficiently detect them based on surface enhanced Raman scattering (SERS) effect. It is an important way to realize SERS-based detection by coating the active, ultrathin, and uniform oxides layer on noble metal nanoparticles, which could indirectly catch and enrich the target molecules on the surface. However, how to efficiently and conveniently realize such heterogeneous coating has been a challenging problem in the literature. In this project, motivated by the idea of surface electrostatic adsorption and colloidal self-assembly, we present a new strategy of surface heterogeneous coating on the nanoparticles based on laser ablation in liquid to one-pot prepare the ultrathin oxides layer-wrapped noble metal nanoparticles; explore the crystalline evolution of the oxides layer and its thickness controlling strategy; investigate the interface structure between the oxide layer and the noble metal nanoparticles and its stability; systematically study the optical properties of the oxide layer-wrapped noble metal nanoparticles, local electromagnetic field distribution and SERS effect, and reveal the influence of the oxides-layer’s microstructure, morphology and composition on the SERS effect and its mechanism and so on. This study could not only provide availability (or highly active SERS substrate) for SERS effect-based detection of the toxic molecules which very weakly interact with noble metals, but also is of scientific significance to understand formation process of oxide coating layer, interfacial bonding property and its influence mechanism on local electromagnetic field.

有机磷神经毒剂等毒性分子与贵金属相互作用非常弱（弱相互作用分子），难以实现基于表面增强拉曼散射(SERS)效应的高效检测。通过在贵金属纳米颗粒表面包覆一层超薄的活性氧化物，间接地捕捉与富集目标分子，是实现此类分子高性能SERS检测的有效途径。而如何高效便捷地实现均匀、超薄的异质包覆，一直是挑战性的难题。本项目基于表面静电吸附-胶体自组装的新思路，提出基于液相激光烧蚀的纳米颗粒表面包覆策略，一步法制备超薄氧化物包覆的贵金属纳米颗粒；探究氧化物包覆层的结晶性演化、厚度控制途径及其界面稳定性；系统研究复合纳米颗粒的光学性质、局域电磁场分布及SERS效应；揭示颗粒微结构、形态、组分等参数对SERS效应的影响及其机制等等。这项研究，不仅为弱相互作用分子的SERS检测提供可实现性(高效的SERS衬底)，同时也对揭示氧化物包覆层的形成过程、界面结合性质及对局域电磁场的影响机理具有科学意义。

基于表面增强拉曼散射(SERS)效应的分子检测具有速度快、灵敏度高、指纹识别等特性。然而，沙林、汞离子、苯等高毒物质缺少与金银贵金属产生强吸附作用的官能团（弱相互作用分子），很难实现基于SERS效应的高效检测。由于氧化物表面存在丰富的悬挂键和更高的化学活性，在贵金属表面包覆一层超薄的氧化物层，有望实现毒性目标分子的高效捕捉和吸附富集。本项目，以贵金属为靶材，以金属盐溶液为反应介质,基于液相激光烧蚀策略一步法实现贵金属纳米颗粒的表面超薄包覆，并研究其对特定毒性分子的SERS效应：发展出了基于液相激光烧蚀的氧化物包覆贵金属纳米颗粒制备新方法，获得了氧化锌、氧化铟、氧化铁、氧化钛、氧化铈、氧化锡等系列氧化物超薄包覆的Ag、Au贵金属纳米颗粒，并成功实现了包覆层厚度、结晶性等参数的可控调节；获得了贵金属纳米颗粒局域电磁场强度和空间分布与其尺寸、包覆层厚度之间的相关性，揭示了氧化物包覆层对金属纳米颗粒薄膜SERS效应的影响与增强机制；以贵金属纳米颗粒为敏感单元构筑了高活性SERS检测芯片，并通过氧化物、有机分子的表面修饰实现了毒性分子的高特异性检测。特别地，通过修饰4-MBA分子，基于表面局域的汞化反应实现了痕量汞离子、有机汞的高选择性检测；从沙林等有机膦毒剂的致毒官能团出发，优选捕捉剂分子并构筑功能化的SERS检测芯片，实现了MPA(沙林模拟剂)、沙林、塔崩、梭曼、VX、芥子气等气相/液相化学战剂的痕量检测；以氧化锡@金复合纳米颗粒为敏感单元构筑双模响应传感器，基于“电学响应”触发“SERS识别”的策略实现了对苯类、硫醇类等VOCs分子的精准识别与在线检测。本项目的执行，不仅提供了一种氧化物超薄包覆贵金属纳米颗粒的通用制备方法，对揭示氧化物包覆层的形成过程、界面结合性质及对局域电磁场的影响机理具有科学意义，同时也为高毒分子的SERS检测提供了材料基础与理论依据。