Study On Interfacial Oriented Etching Of Ag Nanoparticles

Precious metal nanomaterials have a wide range of applications in the fields of organic synthesis,energy and analytic detection because of their unique optical and catalytic properties.So far,a variety of single metal nanomaterial synthesis has made significant progresses.In order to further enhance the performance of single metallic nanoparticles or to obtain new properties that are not possessed by single counterparts,these particles are typically post-treated by the metal displacement reaction.The intervention of the replacement reaction not only realizes the multi-metallization of single material nanoparticles,but also diversifies the morphology of nanomaterials,setting the foundation for studying the relationship between the properties and the structures.However,oriented etching or multi-metalizing of nanoparticles is a highly challenging task,and it is even more difficult to achieve mass production.Based on this,this thesis used Ag nanoparticles as the model particles,achieving the unique bimetallic nanostructures by the oriented displacement reaction with the assistance of the interfacial confinement.The main contents are as follows:(1)Achieve bimetallic "nanorings" by oriented etching of Ag nanospheres located at water/air interface.(2)Achieve bimetallic-cubic "nanocups" by oriented etching of Ag cubes located at water/air interface.(3)Achieve bimetallic "nanometer trough" by oriented etching of Ag nanowires located at water/air interface.All bimetallic nanostructures obtained above were also characterized by transmission electron microscopy(TEM),scanning electron microscopy(SEM),polycrystalline powder X-ray diffraction(XRD)and X-ray photoelectron spectroscopy(XPS).In the case of each type of nanoparticle,the etching depth and width was tunable by adjusting the reaction time.The formation of these unique nanostructures was attributed to site-selective etching mechanism with the assistance of the interfacial confinement.Furthermore,by changing the reaction medium of the etching agent,AgAu,AgPt and AgPd bimetallic "nanocups" were successfully fabricated,achieving the diversification of the bimetal materials.The preliminary study shows that AgAu nanocups have excellent catalytic performances due to their structure and composition effects.These unique bimetallic nanostructures may also have potential applications in nonlinear optics,analysis,microreaction synthesis etc.