外加电压调控具有高密度热点的金/银复合SERS基底的增强机制及性能研究

Currently, it has been demonstrated that the more hot spot (nanogaps with distance < 1 nm between noble metal nanostructures), the easier obtained SERS signals of high intensity. In this project, we plan to conduct our work on the basis of the fabrication of multi-layered Au/Ag hybrid SERS substrates with high-density hot spots. Firstly, monolayered films of monometallic nanoparticles (NPs) were prepared by differently-sized Au NPs and Ag NPs, from which monolayered films with high-density hot spots were screened out as SERS substrates for SERS measurement of common Raman probes. Secondly, multi-layered Au/Ag hybrid SERS substrates were obtained by controllable layer-by-layer construction of monolayered films of Au NPs and Ag NPs. Then, the effect of their thickness (layers of monolayered film) and different arrangement structures (types of monolayered film) on the SERS performance under applied potentials were investigated in detail. I hope that the effect of applied potentials on charge transfer between Au and Ag NPs among multi-layered Au/Ag hybrid SERS substrates with high-density hot spots and the enhancement mechanism of applied potentials on the SERS performance both were explained. Lastly, controllable fabrication of multi-layered Au/Ag hybrid SERS substrates with high-density hot spots can be achieved and higher enhanced factors and reproducible signals of the resulting films can be adjusted by structural design and applied potentials, thus achieving the purpose of conveniently and effectively controlling the activity of substrates and single-molecule test.

现在研究表明热点(贵金属纳米结构中小于1纳米的间隙)越多，越容易得到高强度的表面增强拉曼(SERS)信号。本项目拟以具有高密度热点的多层金/银复合SERS基底的制备展开工作，首先以不同尺寸的金和银纳米颗粒制备单金属的纳米颗粒单层膜，然后筛选具有高密度热点的单层膜并作为基底测试常用拉曼探针分子的SERS信号；接着以所筛选的金和银纳米颗粒单层膜为构筑单元可控搭建多层膜，然后通过外加电压调控，深入研究它们的厚度（单层膜层数）和不同的排列结构（单层膜种类）对其SERS性能的影响，阐明外加电压对具有高密度热点的多层金/银复合SERS基底中金、银之间的电荷转移的影响以及对其SERS性能的增强机制；最后，实现具有高密度热点的多层金/银复合SERS基底的可控制备和通过结构设计和外加电压调控使其具有高增强因子和可重复的SERS信号，从而达到方便、有效地调控SERS基底的活性和实现其单分子监测的目的。

中文摘要：为了得到高强度的表面增强拉曼(SERS)信号，SERS基底需要具备高密度的热点。因此，在本项目的目标就是制备具有高密度热点的多层金/银复合SERS基底。主要研究内容如下：1)以不同尺寸的金和银纳米颗粒制备单金属的纳米颗粒单层膜；2)以所筛选的金和银纳米颗粒单层膜为构筑单元可控搭建多层膜，然后通过外加电压调控，深入研究它们的厚度（单层膜层数）和不同的排列结构（单层膜种类）对其SERS性能的影;3)实现具有高密度热点的多层金/银复合SERS基底的可控制备和通过结构设计和外加电压调控使其具有高增强因子和可重复的SERS信号，从而达到方便、有效地调控SERS基底的活性和实现其单分子监测的目的。取得的重要结果如下：.(1) 通过在柠檬酸钠体系中可控合成不同尺寸的金、银及金-银纳米晶(壳层表面组成不同的金-钯纳米晶，含有不同密度缺陷的金钯纳米晶，金钯合金纳米线网络结构和含不同表面晶面的金钯气凝胶), 然后组装成为大面积的纳米颗粒单层膜，实现了它们在拉曼增强(SERS)方面的应用。(ACS Appl. Mater. Interfaces, 2018, 10, 602; 2018, 10, 23081; & 2019, 11, 17637; Optics Letters, 2018, 43, 1179; Organic Electronics, 2018, 52,309-316; J. Mater. Chem. C, 2018, 6, 637; J. Mater. Chem. B, 2019, 6，7675; Nanophotonics, 2020, 9, 2537; Nanoscale, 2020, 12, 16934 & 2021, 13, 14925). (2) 通过在在CTAB/CTAC体系中可控合成一系列双金属金基纳米晶（三八二十四面体金@钯纳米颗粒，超支化的，核壳结构的六八四十八面体(HOH)金@金钯纳米颗粒，超宽金棒）作为多功能材料，实现了它们在电催化和拉曼增强方面的应用。(Nanoscale, 2018, 10, 22302; J. Mater. Chem. A, 2018, 6, 7675; Chemistry- A European Journal, 2021, 27, 7549).(3) 其他发表的和未发表的工作见报告正文.