Bi-functional Semiconductor/noble Metal Composites For Catalyzing Degradation And SERS Monitoring In Real Time

Surface-enhanced Raman spectroscopy（SERS） was explored from the experiment of electrochemical Raman scattering originally. As the coinage metals adsorbing target molecules, the signal of Raman scattering will be enhanced dozens of times. Recently, it has been fleetly employed in many investigations because of its extremely high sensitivity that can down to the single-molecule level. Since tremendous enhancement effect depends on an excellent substrate, researchers have explored various materials and different morphology for many times, especially Au, Ag, Cu. At the same time,transition metals and semiconductors also have attracted scientists’ attention on account of their own-special qualities that could be used in fields liking environment testing,biological sciences, chemical analysis and so on.In this thesis, we prepared bi-functional semiconductor/noble metal composites for catalyzing degradiation of organic pollutants and SERS monitoring simultaneously in real time. The primary are showed as follows:（1） Cobalt oxide（Co₃O₄）, the p type transition metal, owns two unique band gaps that attracts a lot of attention. Previous workers confirmed Co₃O₄ having the peroxidase-like activity could promote H2O2 to oxidize tetramethyl benzidine（TMB）.We prepared ultrathin hexagonal Co₃O₄ and then successfully obtained composite Co₃O₄/Au by modifying gold on it. The composite could used as a catalyst to degradate organic pollutant. Meanwhile, fabricating the composite as the SERS substrate, it can enhance the Raman signal of R6 G and the enhancement factor is 7.6 × 104. So this bi-functional composite Co₃O₄/Au could be used to catalyze process of degrading R6 G dye molecules by SERS monitoring in real time.（2） Disulphide transition metal has been researched deeply at electricity, photology,magnetism and so on due to many of their own unique properties. In this part of the thesis, composite Co S₂/Au with high crystallinity and purity was fabricated. The experiment of oxidizing o-phenylenediamine（OPD） proved that Co S₂/Au composite had efficient peroxidase-like activity. It also could facilitate H2O2 to degrade R6 G molecules. At the same time, it can emerge the excellent SERS performance with the enhancement factor up to 3.2× 105. Then we applied Co S₂/Au as SERS substrate to monitoring the process of degrading R6 G molecules in real time. We also studied the relationship among the intensity of SERS, concentration of R6 G molecules and reaction time to quantitative research further.（3） Semiconductor Co S is considered to be a kind of environmental material in aspects as lubrication, magnetism, electricity, catalyst and so on. In this part, upon preparing of Co S successfully, we synthesized Co S/Au composite by adding reductor into the solution of gold chloride acid. It enhanced the SERS signal of R6 G with the enhancement factor up to 1.7× 105. Co S/Au also could rapidly promote the process of degrading R6 G molecules. It is a remarkable bi-functional materials that could be served as SERS substrate to monitor the degradation reaction of R6 G molecules.