【作者】 李娜；

【导师】 朱储红；

【作者基本信息】 安徽大学 ， 无机化学， 2024， 硕士

【摘要】 表面增强拉曼散射（SERS）是一种可以准确检测分子的指纹识别技术。普通拉曼信号可以被SERS基底显著放大6-12个数量级。SERS因其高灵敏度而被广泛应用于生物分析、环境监测、食品检测、催化表征等领域。设计、探索和构建高效的SERS活性纳米材料作为SERS基底,是推动SERS技术发展和应用的关键。近年来,SERS活性纳米材料逐渐从最初的单组分材料（例如,金属、半导体,石墨烯和金属有机框架等）向具有多种功能性的多组分复合材料扩展。复合结构SERS基底因其独特的结构和性质,在提高检测灵敏度、扩大应用范围、增强功能性等方面具有显著优势。但是,对于某些低浓度分析物的检测,要达到理想的检测限仍然存在挑战。通过使用高性能材料、优化纳米结构组装方式、提高分析物与基底的相互作用等途径提高复合结构SERS基底的灵敏度,对SERS技术的发展和应用具有重要意义。本论文采用简便快速的方法设计了两种高效的复合结构SERS基底,并通过优化基底的结构参数和SERS热点分布,显著提高了基底的均匀性和SERS检测的灵敏度。具体研究内容如下:（1）采用水热法和电沉积技术制备SERS灵敏度高、信号均匀的银纳米颗粒修饰的氧化锌纳米棒阵列。首先,通过水热法在氧化铟锡（ITO）导电玻璃上制备三维ZnO纳米棒阵列;然后通过银镜反应和种子辅助电沉积法在ZnO纳米棒表面修饰高密度的银纳米颗粒。ZnO与Ag相结合可以改变两者间的电子云密度以及待测分子与ZnO表面间的电荷转移,从而显著提高SERS活性和检测灵敏度。密集分布在氧化锌纳米棒表面的银纳米颗粒之间存在大量数纳米的间隙,可以提供大量的热点,为高SERS活性提供电磁增强方面的保障。与对应的二维结构SERS基底比较,三维结构能够在激发光束内提供更多的热点,从而获得更强的SERS信号。制备的SERS基底对罗丹明6G（R6G）、腺嘌呤、4-氨基苯硫酚（PATP）的检测下限分别达到10^-13 M、3×10^-11 M和1.6×10^-12M。该SERS基底的增强因子高达2.7×10⁸。同时,利用该基底检测探针分子得到的SERS光谱特征峰强度的相对标准偏差值（RSD）均小于10%,表明该基底具有良好的SERS信号均匀性。此外,由于复合基底具有光催化活性,利用紫外光照射可以完全分解基底表面吸附的有机分析物,从而实现自清洁和基底的循环利用。因此,所制备的银纳米颗粒修饰的ZnO纳米棒阵列可作为高灵敏度、可重复使用的三维SERS基底,在环境污染监测和生物医用分析等方面具有重要应用前景。（2）针对上一工作所制备的基底存在生物相容性和吸附能力较差的问题,我们采用简单易行、成本低廉的两步法制备信号均匀、吸附能力强的非贵金属SERS基底。该基底由超薄氧化石墨烯（GO）包裹的二氧化钼纳米颗粒（MoO₂-NPs）组成。通过水热法合成具有局域表面等离激元共振（LSPR）效应的MoO₂-NPs,然后在水溶液中通过范德华力将超薄GO片包裹在MoO₂-NPs表面,形成超薄GO/MoO₂-NPs复合材料。MoO₂-NPs的表面具有大量凸起,能够形成等离激元热点,从而具有显著的SERS活性。超薄GO片的大部分表面紧密地包裹在MoO₂-NPs上。因此,具有巨大比表面积和高吸附能力的GO片所捕获的大部分分析物分子位于或接近MoO₂-NPs热点区域,因而该复合结构SERS基底具有高SERS灵敏度。该基底对R6G的检测下限为6.98×10^-14 M,增强因子高达1.12×10⁸,且光谱均匀性良好（RSD=9.7%）。此外,该基底还具有优异的结构稳定性和化学成分稳定性（即抗氧化性、耐酸性和耐碱性）。因此,超薄GO/MoO₂-NP基底在基于SERS的痕量化学分子检测中具有广阔的应用前景。更多还原

【Abstract】 Surface Enhanced Raman Scattering（SERS）is a fingerprinting technique that can accurately detect molecules.Ordinary Raman signals can be significantly amplified by 6-12orders of magnitude by SERS substrates.SERS is extensively applied across various fields,including bioanalysis,environmental monitoring,food testing,and catalytic characterization due to its high sensitivity.Designing,exploring and constructing efficient SERS-active nanomaterials as SERS substrates are key to promoting the development and application of SERS technology.In recent years,SERS-active nanomaterials have gradually expanded from the initial single-component materials（e.g.,metals,semiconductors,graphene,and metal-organic frameworks,etc.）to multicomponent composites with multiple functionalities.Composite structured SERS substrates have significant advantages in improving detection sensitivity,expanding application range,and enhancing functionality due to their unique structures and properties.However,challenges remain in achieving the desired detection limits for certain analytes at low concentrations.Improving the sensitivity of composite structured SERS substrates by using high-performance materials,optimizing the nanostructure assembly method,and improving the analyte-substrate interaction are of great significance for the development and application of SERS technology.In this thesis,two efficient composite structural SERS substrates were designed by a simple and rapid method,and the homogeneity of the substrates and the sensitivity of SERS detection were significantly improved by optimizing the structural parameters of the substrates and the distribution of SERS hot spots.The specific research contents are as follows:（1）Hydrothermal synthesis and electrodeposition techniques were used to prepare silver nanoparticle-modified zinc oxide nanorod arrays with high sensitivity and homogeneous signal.First,three-dimensional ZnO nanorod arrays were prepared on indium tin oxide（ITO）conductive glass by hydrothermal method;Then high-density silver nanoparticles were modified on the surface of ZnO nanorods by silver mirror reaction and seed-assisted electrodeposition.The combination of ZnO with Ag can change the electron cloud density between the two and the charge transfer between the molecule to be tested and the ZnO surface,which greatly improves SERS activity and detection sensitivity.The large number of gaps of several nanometers between the silver nanoparticles densely distributed on the surface of ZnO nanorods can provide a large number of hot spots for high SERS activity in terms of electromagnetic enhancement.Compared with the corresponding two-dimensional structured SERS substrate,the three-dimensional structure can provide more hot spots within the excitation beam,resulting in a stronger SERS signal.The limits of detection of rhodamine 6G（R6G）,adenine,and 4-aminothiophenol（PATP）by the prepared SERS substrate were up to10^-13 M,3×10^-11 M,and 1.6×10^-12 M,respectively.The enhancement factor of this SERS substrate was as high as 2.7×10⁸.At the same time,the relative standard deviation values of the characteristic peak intensities of the SERS spectra obtained by detecting the probe molecules using the substrate were all less than 10%,indicating that the substrate has good SERS signal homogeneity.In addition,due to the photocatalytic activity of the composite substrate,the organic analytes adsorbed on the surface of the substrate can be completely decomposed using UV light irradiation,thus realizing self-cleaning and recycling of the substrate.Therefore,the prepared silver nanoparticle-modified ZnO nanorod arrays can be used as highly sensitive and reusable SERS substrates with important applications in environmental pollution monitoring and biomedical analysis.（2）In response to the poor biocompatibility and adsorption capacity of the substrates prepared in the previous work,we used a simple and inexpensive two-step method to prepare non-precious-metal SERS substrates with uniform signals and strong adsorption capacity.The substrate consists of ultrathin graphene oxide（GO）wrapped molybdenum dioxide nanoparticles（MoO₂-NPs）.MoO₂-NPs with localized surface-isolated exciton resonance（LSPR）effect were synthesized by a hydrothermal method,and then the ultrathin GO sheets were wrapped around the surface of MoO₂-NPs by van der Waals forces in aqueous solution to form ultrathin GO/MoO₂-NPs composites.MoO₂-NPs have a large number of projections on their surfaces,which are capable of forming an equipartitioned exciton hotspot,resulting in significant SERS activity.Most of the surface of the ultrathin GO sheet is tightly wrapped around the MoO₂-NPs.As a result,most of the analyte molecules captured by the GO sheet with huge specific surface area and high adsorption capacity are located at or close to the hot spot region of MoO₂-NPs,and thus the composite structured SERS substrate has high SERS sensitivity.The substrate showed a lower detection limit of 6.98×10^-14 M for R6G,an enhancement factor as high as～1.12×10⁸,and good spectral homogeneity（RSD=9.7%）.In addition,the substrate also exhibited excellent structural stability and chemical composition stability（i.e.,oxidation,acid and alkali resistance）.Therefore,ultrathin GO/MoO₂-NP substrates have a promising application in SERS-based detection of trace chemical molecules.更多还原