Construction,Mechanism And Performance Of Porous, Hollow Noble Metal Nanostructure

Noble metal nanostructures have extensive applications due to their unique chemicophysical properties. It is well known that the properties of noble metal nanostructures usually depend on their physical parameters including shapes, sizes, compositions and structures. So far, researchers have developed many technologies for tailoring and tuning the properties of metal nanostructures. These methods allow us effectively designing and controllably synthesizing noble metal nanostructures with stable structures and specific properties, which might have applications in many fields especially electrocatalysis, fuel cells, biochemical dectection, pharmaceutical and sensing. In this dissertation, we prepared different shapes of hollow and porous noble metal nanostructures through galvanic replacement reaction and selective etching. Moreover, their growth mechanism, catalytic and self-healing properties were also studied. Our research mainly includes the following three parts:The preparations of Ag-Pt bimetal and hollow nanowires. Through galvanic reaction between Ag nanoparticles and Pt(IV), various Ag-Pt nanostructures were prepared. In addition, we investigated syntematically the effect of experimental factors, such as Ag N03、PDDA、TEG、NaOH, in the formation of Ag-Pt nanowires. Their performance toward electrochemical catalytic such as methanol and ethanol oxidation responses have been intensively studied. The results show that hollow nanostructures have excellent catalytic performance due to the presence of highly active sites and large specific surface.The controlled synthesis of Au-Pt nanoring through selective-etching and selective-growth. In our experiment, the dissolved 〇2 in the solution can act as an etching agent will selectively etches the edges of Au polyhedrons, which creates highly active sites. Meanwhile, Pt ions were reduced to Pt atoms which selectively grew on these active sites. The depositions of Pt on the active sites protect the Au atoms of these sites against further etching and move the etching to {111} facet without Pt layer. Finally, ring Au-Pt nanostructure formed after most of the Au was etched. Besides, we also studied the influence of other reaction conditions, such as reaction time and reaction temperature.The self-healing growth of Au-Pt nanoring. By using Au-Pt nanoring as template, we realize the self-healing growth through using various noble metal as repairing agents, include HAuCU、AgN〇3 、H2PdCU etc. by adjusting the mole ratio of repairing agents and reducing agent. The results show that HAuCU and AgNOs serve as repairing agents could complete the repairation. However, HiPdCU is not successful. Thus, the type of repairing agent and the amount of repairing agent are two key factors during the healing growth.