Structural Control Of Noble Metals And Applications In Catalysis And SERS

Noble metal nanoparticles have great potential application in the fields ranging from optics,electrics,magnetics and catalysis,whereas those application properties are directly affected by their size,shape and structure.Therefore,much attention has been paid to accurately control the size,morphology and structure of noble metal nanoparticles.In this paper,we control the morphology of noble metal by using capping agent sodium citrate,different reducing agents,sulfonic acid groups on the surface of polystyrene and polymer brushes.the research works are as follow:(1)Three-dimensional gold mesoflowers(3D-AuMFs)were prepared through a facile,seedless and one-step homogeneous solution route with the assistance of citrate as capping agents.The influence of reaction temperature and the amount of sodium citrate on the morphology and size of 3D-AuMFs were investigated,and the possible formation mechanism of 3D-AuMFs was discussed.The results shows that the 3D-AuMFs has excellent catalytic activity for the reduction of 4-nitrophenol(4-NP)and a highly sensitive in surface-enhanced Raman scattering(SERS)for the detection of 4-mercaptopyridine(4 MP).The multi-branched gold nanoparticles were prepared by different reducing agents.The effects of the reaction temperature and the amount of capping agents and reducing agents on the morphology and size of the multi-branched gold nanoparticles were studied.(2)The Pd2+ ions were attracted to sulfonated polystyrene(PS-SO3H)microspheres through the electrostatic interactions,then PS-SO3H@Pd composite were obtained by in situ chemical reduction,and the pyrrole monomer was polymerized on the surface of PS-SO3H@Pd to obtain polypyrrole(PPy)shell.Finally,the Pd@PPy hollow capsules were prepared by selective etching of the PS core.The as-prepared Pd@PPy hollow capsules showed excellent catalytic activity on reduction 4-nitroaniline(4-NA),because of the high density of palladium nanoparticles.Moreover the Pd@PPy hollow capsules exhibited outstanding reusability,due to the protection and sustainability of PPy shell.(3)The poly(2-vinylpyridine)(P2VP)brushes were grafted on the silicon surface via “surface-initiated polymerization by photografting and photopolymerization”(SIPGP).The noble metal ion was attached by polymer brushes via the electrical interaction between pyridine groups and AuCl4-ions.Then,P2 VP brushes loading AuCl4-ions were exposed to pyrrole vapor,one-step synthesized Au nanoparticles and conducting polymer polypyrrole(PPy).Au-PPy composites with different morphology could be obtained through controlling the thickness of P2 VP brush and reaction time.The Au-PPy composites were used as substrates for SERS,and they exhibited excellent Raman enhancement performance.