Noble Metal-ZnO Nanorods For Solid Phase Microextraction-Surface Enhanced Raman Spectroscopy

With the development of economy, the environment problem has become a global problem. Most of the environmental pollutants would threaten human health and ecosystems. The increasingly serious environmental problems require researchers to develop new convenient and fast methods of analysis. Sample pretreatment technology was needed in environment detection due to the complicated situation. As a new sample preparation technique with simple, time-efficient, sensitive and solvent-free characteristics, solid-phase microextraction (SPME) combines sampling and preconcentration of the target compounds from complex sample matrices in just one step. Surface enhanced Raman spectroscopy (SERS), a high sensitivity and nondestructive spectroscopy technology in structure analysis, can provide characteristic information of the molecules. The solid phase microextraction-surface enhanced Raman spectroscopy (SPME-SERS) integrated fiber, combining the pretreatment and determination functions, provides an in situ detection technique. The "hot spots" and the reusable problems of the SPME-SERS fiber have always been the focus of attention.In this dissertation, Ag/Au-ZnO nanorod arrays on stainless steel fiber was used as a 3D SPME-SERS fiber. Meanwhile, the SERS-active SPME fiber owns the self-cleaning property for ZnO photocatalytic degradation. The main contents can be summarized as follows:1. The surface of ZnO nanorods were modified amino silane (3-Aminopropyltriethoxysilane), high SERS-active Ag NPs were deposited on ZnO nanorods by self-assembly method and achieved a 3D SERS-active SPME fiber. The fiber provides more molecular binding sites due to the high surface-to-volume ratio of the ZnO nanorods. The noble metal-semiconductor composites show higher SERS enhancement due to the contributions from both the electromagnetic enhancement and semiconductor supporting chemical enhancement. The SPME-SERS fiber has good uniformity and stability and can directly extract and detect the thiram in the water.2. Au nanoparticles coated ZnO nanorods (ZnO NRs) were fabricated on stainless steel fiber as a 3D SERS-active SPME fiber. P-Aminothiophenol (PATP) was selected as probe molecules to study the influence of sputtering time on the Raman activity. The SPME-SERS fiber was immersed into water to extract and detect crystal violet and malachite green. Meanwhile, the fiber exhibited good photocatalytic activity and could clean itself via UV photocatalytic degradation. As a SERS-active SPME fiber, the self-cleaning function suggests a new route to achieve the fiber reused.