Molecular Simulation On The Properties Of New Metallic Nanoclusters Catalysts

Metal clusters,as an important nanoclusters specie,is known as the fourth generation catalyst and has been the research focus because of the good catalytic property.At present,it is really difficulty to study the structures and thermal stability properties of clusters with experimental method.It is difficult to achieve fine control by experiment method,because of many complex factors,such as size,composition and atomic order.So a simulation calculation method is indispensable and necessary.This thesis mainly is to study the structure and thermal stability of bimetallic and trimetallic nanoclusters and nanowires using Monte Carlo and molecular dynamics simulation method.It is very significant for the conduct of synthetic and control high-performance alloy system.After studying the different compositions and sizes of the Ag-Pt-Ni nanoclusters,it is found that all of them shows the same rule that silver atoms tend to occupy surface,platinum atoms prefer subsurface,while the core is dominated by nickel atoms.After the molecular dynamics simulation of Ag-Pt-Ni nanoclusters,there is no monotonous change between compositions and melting points.After studying the thermal stability of bimetallic and trimetallic Pt-based nanoclusters,the thermal stability of the bimetallic system order is Ni-Pt>Fe-Pt>Cu-Pt>Co-Pt and Fe-Ni-Pt shows the best thermal stability among trimetallic system.In addition,by comparing three different compositions of Ni-Co-Pt system,we find the mixed system shows best stability and the diamond crown is the worst.Cu-Ni nanowires was studied finally,we find that with the increase of chemical potential difference values between nickel and copper,copper atoms began from the surface position to occupying all the location of the nanowires gradually.We also found that single Cu atoms are more likely to tend to be internal migration.Controlled by heating up the phase transition process of Cu-Ni nanowires,thermal stability of the system is on the decline as the content of Cu increased.