Controllable Synthesis Of Au@Pt Core-shell Nanomaterials And Their Application In Catalysis And SERS

Pt-based nanomaterials have been widely used in industrial catalysis,fuel cell,and water pollution treatment.Platinum can form bimetallic structures with many noble metals.The synthesis of Au-Pt bimetallic materials expercially Au@Pt core-shell structures and their application in catalysis and SERS have become hot topics in the current study due to their unique optical properties and excellent catalytic properties.However,only a few Au@Pt core-shell nanostructures have been synthesized based on complex-structured Au nanoparticles and especially few studies have been carried out to systematically investigate the controllable and selective deposition of Pt on the special sites of the Au nano-templates.In the present thesis,a facile temperature-controlled method for selective depositing Pt on complex-structured hexoctahedral Au nanoparticles(Au HNPs)was proposed to prepare Au@Pt core-shell nanostructures by controlling the synthesis temperatures.Based on the comprehensive characterization of the Au@Pt nanostructures' morphology,composition,optical,catalysis and SERS properties,the high performance of the proposed Au@Pt nanostructures on sensitive SERS-based in situ,real-time monitoring of catalytic reaction was investigated and verified,and their application in high sensitive colorimetry and SERS detection of Hg2+ in water was studied.The concent of the thesis is as follows:Firstly,a simple method for preparing hexoctahedral gold nanoparticles was proposed.In this one-pot and seedless synthesis,the Au HNPs were prepared by using hexadecyltrimethylammonium chloride as a surfactant and reducing chloroauric acid with ascorbic acid.The Au HNPs have good monodispersity,stability and SERS activity.Secondly,a facile and temperature-controlled method for selectivly depositing Pt on complex Au HNPs was proposed to prepare Au@Pt core-shell nanostructures.Pt can be preferentially deposited on the sharp tips,edges and the entire surface of the particles.The synthesiesed Au@Pt core-shell nanomaterials have good catalysis and SERS performance,and the catalysis reaction monitored by in situ SERS was performed.Thirdly,a colorimetric/SERS dual-mode sensor for detecting Hg+ ions in water was designed by using the proposed Au@Pt nanoparticles.Hg+ ions can inhibit the activity of peroxidase of Au@Pt nanoparticles,and then reduce the reactionrate of the oxidation between hydrogen peroxide and tetramethylbenzidine(TMB)in the presence of Au@Pt nanoparticles,which may result in the change of both the solution color and the SERS signal of TMB to acheive the colorimetric/SERS dual mode detection Hg ions.The colorimetric method can intuitively detect the Hg+ ions in water and a more sensitive detection can be obtained by SERS.