SERS Study On Charge Transfer Effect Of Semiconductors And Their Assemblies

Surface enhanced Raman spectroscopy(SERS)is a surface enhanced technology.The successful detection of analytes is affected by many factors.The most important is the choice of substrate.The application of SERS is inseparable from the development of substrate.Semiconductors are considered to be the most ideal SERS substrate.Not only improves the enhancement effect of SERS,but also widens the practical application of itself.Taking semiconductor ZrO₂as the main body,this paper studies the SERS of charge transfer effect by different methods,different metal ions doped ZrO₂and self-contained semiconductor/molecule/metal sandwich structure.The main research contents of this article are as follows:(1)Preparation of Mg and Mg+Zn ion doped ZrO₂nanoparticles(NPs)as Sol-gel method for contrast enhancement of SERS substratesIn this paper,doped ZrO₂was prepared as SERS substrate by Sol-gel method using three different doped metal ions(Mg and Mg+Zn)and different molar doping amount(0.5%-5%).The results were characterized by XRD,SEM,Raman and UV-Vis.Mg and Mg+Zn exist in ZrO₂NPs in ionic state.The particle size calculated by XRD is basically consistent with SEM.Compared with undoped zirconia,doped metal ions can improve the SERS strength of semiconductors,and the doped SERS with 1%molar ratio has the strongest effect and the highest charge transfer degree.Compared with single ion and double ion doping,the SERS intensity of double ion Mg+Zn doping is higher than that of single ion Mg.It is mainly because double ion doping further improves the surface defects of semiconductors and changes the strength of SERS signal.(2)Comparative study of Mg,Zn and Mg+Zn ion doped ZrO₂NPs prepared by hydrothermal method as SERS enhanced substrate and practical application of drug molecule(LVFX)Doped ZrO₂was prepared as SERS substrate by hydrothermal method using three different doped metal ions(Mg,Zn and Mg+Zn)and different molar doping amount(0.5%-5%).It can be seen by XRD,SEM,Raman and UV-Vis characterization.The prepared doped ZrO₂is mainly tetragonal phase(T),Mg,Zn and Mg+Zn exist in ZrO₂NPs in the form of ionic state,and there are no other compounds.The particle size calculated by XRD is basically consistent with SEM.Compared with undoped ZrO₂,the doped SERS with 1%molar ratio has the strongest effect and the highest charge transfer degree.Comparing the two kinds of single ion and double ion doping,the SERS intensity of double ion Mg+Zn doping is higher than that of single ion Mg and Zn.Compared with enhancement factor(EF)prepared by sol-gel method and hydrothermal method,the SERS intensity of Mg+Zn ion doped ZrO₂prepared by hydrothermal method is the highest,and is used as a substrate for the detection of the LVFX of drug molecules.The results show that the SERS has higher SERS strength.(3)SERS application of self-assembled ZrO₂/MBA/Ag(Au)sandwich system and other structuresZrO₂/MBA/Ag(Au)sandwich system was synthesized by self-assembly.In order to explore the charge transfer mechanism,the reverse assembly of Ag(Au)/MBA/ZrO₂and ZrO₂+Ag(Au)/MBA system was carried out.According to the Raman and UV-Vis characterization results,there are obvious differences in Raman shift and SERS intensity of4-MBA molecules between sandwich structure components and ZrO₂/MBA and Ag(Au)/MBA,which is due to the introduction of metal and its interaction/synergy with ZrO₂.In the self-contained sandwich system,ZrO₂/MBA/Ag(Au)has the strongest intensity,and the introduction of silver in the system is stronger than the SERS signal of gold.The enhancement behavior of 4-MBA in sandwich structure assembly strongly depends on the properties of metals and 4-MBA molecules,which affects the CT effect of ZrO₂-to-molecule and produces higher SERS signals.