宽带隙二维h-BN构筑金属纳米粒子/阵列间隔层的三维SERS基底的研究

Surface-enhanced Raman scattering (SERS), capable of providing high-resolution structure information, has an important application prospect in the fields of analysis and detection. One of the key prerequisites for SERS sensing is the preparation of efficient substrates. However, how to get a SERS substrate with high sensitivity, good stability and strong reusability remains challenging. In this project, three-dimensional (3D) SERS substrates of metal nanoparticle/hexagonal boron nitride (h-BN)/ordered metal nanoarray with high-density electromagnetic hot spots will be fabricated to improve the Raman activity of substrates by using h-BN as interlayer for generating nanometer-scale gaps. Here, h-BN possesses excellent SERS properties, atomic thickness, electrical insulativity and high thermal stability. The influences of the electronic structure of h-BN and metal morphologies on the properties of surface plasmon polaritons and SERS sensing performances of the 3D systems will be systematically studied by exploring the device processes and tuning the structure configurations, and the multi-component analysis and trace detection will be conducted by taking pesticide as an example. In theory, the surface plasmon resonance spectra and the electromagnetic field distributions of the 3D structures will be simulated by utilizing finite element method, and the charge transfer between molecules and substrates and other interactions will be calculated based on first-principles density functional theory for studying the electromagnetic enhancement and chemical enhancement mechanisms. This study will provide theoretical and experimental basis for SERS sensing applications of h-BN-metal hybrids.

表面增强拉曼散射(SERS)光谱能提供高分辨率结构信息，在分析检测领域具有重要应用前景。有效基底是进行SERS传感的关键前提。目前，如何获得一种灵敏度高、稳定性好和可重用的SERS基底仍然具有挑战性。本项目拟采用具有优良SERS特性、原子层厚度、电绝缘性和高热稳定性的宽带隙二维六方氮化硼(h-BN)材料作为间隔层以构建纳米尺度间隙，研制具备高密度电磁热点的金属纳米粒子/h-BN/有序金属纳米阵列三维SERS基底来提高基底拉曼活性。通过摸索制备工艺和结构调控，系统研究h-BN电子结构和金属形貌对三维体系表面等离激元性质和SERS传感性能的影响，并以农药为例进行多组分分析和痕量检测。在理论上通过有限元方法模拟三维体系表面等离激元共振光谱和电磁场分布，以及第一性原理计算分子-基底电荷转移等相互作用，揭示电磁增强和化学增强机理。最终二者结合为h-BN与金属复合体系的SERS应用提供理论和实验基础。

由于具有高灵敏度和无损检测的特点，表面增强拉曼散射(SERS)光谱技术在物理、化学、生物学、医学等领域展现了巨大的应用潜力。本项目中，我们利用具有原子层厚度、良好的电绝缘性和高热稳定性的宽带隙二维六方氮化硼(h-BN)材料作为两层金属纳米结构之间的间隔层，制备了金属纳米粒子/h-BN/有序金属纳米阵列三维SERS基底。通过摸索制备工艺，探究了圆盘形、六边形、星形等有序金属纳米阵列的制备方法，分析了不同结构的表面等离激元性质和SERS传感性能。选用优化的三维结构，对罗丹明6G、晶体紫等分子的SERS检测极限低至0.1pM，并实现了同一样品中两种分子的共同检测。在理论上通过有限元方法模拟了三维体系的电场分布，发现h-BN原子层构建的纳米间隙位置处产生了非常强的电场增强。由于电磁增强引发的SERS增强正比于电磁增强的四次方，这解释了三维体系高SERS传感灵敏度的原因。此外，由于h-BN具有低的电子迁移率，被h-BN掩埋的银纳米粒子能够保持较长时间的稳定性，与此相比，石墨烯由于高的电子迁移率而使银纳米粒子更易氧化。本项目研究结果将为h-BN基SERS基底的制备和应用提供理论基础和技术支持。