Noble Metal Nanocrystals:Galvanic Replacement Corrosion,Morphological Control And Their Properties Research

In this paper,the Galvanic replacement reaction of noble metal nanocrystals with different morphology is mainly researched.Zero-valent nanocrystals with relatively low activity?such as Ag nanocrystals?are replaced by relatively active noble metal ions(such as AuCl₄^-1)at suitable temperature.The surface morphology and the components of the alloy are also carefully controlled.Besides,the surface-enhanced Raman scattering?SERS?of alloy due to surface plasmon resonance arising from the evolution of surface roughness and micro-nano structure,enhanced electrical properties from thin-film after nanocrastal assembly and potential applications in cell adhesion are explored in detail.The large-scale assembly of nanostructured building blocks to be bulk flexible film with multifunctional applications is the key point in colloidal nanomaterials research.In this article,the centimeter-scale flexible conductive film by oriented stacking of Ag nanoplates on the polyethylene glycol terephthalate?PET?flexible substrate was formed with an ideal Ohmic contact and low resistance?112?/cm?.Via solid-liquid interface Galvanic replacement reaction with HAuCl₄,Au-Ag alloy nanoplates film was obtained with enhanced conductivity?10.2?/cm?controllable surface roughness.The optimized surface roughness of such flexible conductive film enabled the ultrasensitive SERS detection of explosives 2,4,6-trinitrotoluene?TNT?and 1,3,5-trinitroperhydro-1,3,5-triazine?RDX?,and the differentiation of TNT and RDX under low concentrations?10 nM?.Moreover,the synergistic nanoscale and microscale surface roughness of such Au-Ag alloy nanoplates film endowed good biocompatibility and demonstrated applicable biological cell adhesive performance.Cu nanoparticles?containing tetrahedron and nanocube?were prepared by reaction between glucose and CuCl₂.Ag-Cu alloy nanoparticles were obtained by Galvanic replacement reaction between Ag⁺solution and Cu nanoparticles.The degree of corrosion and morphology of Ag-Cu alloy nanoparticle were regulated by the reaction temperature,the concentration of Ag⁺solution and the type of capping organic ligands.The presence of Ag was confirmed by UV-Vis,TEM and SEM,and the formation of Ag-Cu alloy was also confirmed by XRD characterization and EDS of the samples.