Interface-oriented Etching Of Ag Nanocubes And Nanowires,and Au/Ag Core/Shell Nanocuboids

Asymmetric hollow noble metal nanomaterials have potential applications in photonics,catalysis,nanoelectronics,chemical sensing and biomedical care.Galvanic replacement reaction has been considered as the most effective method for preparing hollow nanostructures.However,most of the nanostructures obtained by galvanic replacement reaction inherits the symmetry of the original nanoparticles,such as nanoframes,nanocages,nanotubes,etc..To break the symmetry of original nanoparticles,the orientation of galvanic replacement reaction have to be controlled.Therefore,in this thesis,by employing the interface confinement,Ag nanocubes,Ag nanowires and Au/Ag core/shell nanocuboids as the model nanoparticles were transformed into a series of unprecedented asymmetric hollow nanostructures,achieving asymmetric etching of nanoparticles,and the catalytic performances of some of the resulting nanostructures were also investigated.The main contents are as follows:?1?Based on the strategy of oil/water interfacial assembly of NPs,Ag nanocubes?average side-length,¹00 nm?were assembled into a monolayer at water/toluene interface.After evaporation of toluene,by changing the reaction medium of etching agent?11?AgAu,PtAg and PdAg bimetallic nanocups were successfully fabricated at water/air interface by introducing etching agent(AuCl₄^-,PtCl₆^2-or PdCl₄^2-?8?,achieving asymmetric etching of Ag nanocubes at room temperature.?2?Based on the strategy of oil/water interfacial assembly of NPs,Au/Ag core/shell nanocuboids were assembled into a monolayer at water/toluene interface.After evaporation of toluene,Au/AgAu,Au/AgPt and Au/AgPd yolk/shell nanostructures were successfully fabricated at water/air interface by introducing etching agents(AuCl₄^-,PtCl₆^2-or PdCl₄^2-?8?,achieving asymmetric etching of Au/Ag core/shell nanocuboids at room temperature.?3?Based on the strategy of oil/water interfacial assembly of NPs,Ag nanowires were assembled into a monolayer at water/toluene interface.After evaporation of toluene,AuCl₄^-aqueous solution was injected into the water phase,AgAu nanotroughs were successfully fabricated.Also,the catalytic performances of the AgAu nanostructures towards p-nitrophenol were evaluated.The results indicated that the catalytic performance of AgAu nanostructures depends on the etching time.AgAu nanotroughs obtained after 24-h etching exhibited the best catalytic performance,¹50 times better than that of pure Ag nanowires.