Kinetic Behavior Of Alloy Nanoparticles And The Small Molecular Gases Adsorbed On Them

The following three parts are calculated in this paper based on the constant temperature molecular dynamics simulation method and the first principles density functional theory（FPDFT）:（1）The annealing behaviors of Au-Pd,Au-Ag and Au-Pt bimetallic clusters with different sizes and compositions.（2）Geometric and electronic properties of pure metal clusters(Au₁₃ and Pt₁₃)and mixed metal clusters(Au₁₂Pt and Pt₁₂Au).（3）The ground state structure characteristics of Rh_n（n=6,7）clusters and the ground state and electronic properties of small molecules（H₂,O₂,N₂,NO,CO,NO₂,CO₂,N₂O）adsorbed on Rh_n（n=6,7）clusters.The main conclusions are as follows:（1）Through analysing the annealing structures,the segregation behavior of Au atoms in Au-Pd and Au-Pt can be deduced as follows: When the proportion of Au atoms is less than Pd or Pt atoms,the Au atoms tend to occupy the surface.When the gravity of the Au atoms and Pd or Pt atoms are close,the majority of the Au atoms occupy the surface of the cluster.The segregation of Ag atoms occurs in the Au-Ag clusters,which is similar to that of Au atoms in Au-Pd（Au-Pt）clusters.With the increasing of Au atom,the curve of δ-CV of the Au-Pt cluster will change from disorder to order.（2）By using FPDFT,the geometric and electronic properties of pure metal clusters(Au₁₃ and Pt₁₃)and mixed metal clusters(Au₁₂Pt and Pt₁₂Au)are calculated.It has found a new candidate for the ground-state of Pt₁₃,and there exists closer isomers energetically of the pure 13-atom clusters(especially for Au₁₃)to the ground-state,but the doping can depress the isomerization to the ground-state of the pure clusters.The calculated vertical ionization potentials（VIPs）and vertical electron affinities（VEAs）of Au₁₃ are close to the experimental data,and the three dimensional（cage-like）structure is the closest one.Doping has little effect on VIPs and VEAs of the pure Pt₁₃ and Au₁₃ clusters.However,doping has much effects on the distributions of d electrons near the Fermi energy,which may influence the catalytic activities of the mixed clusters strongly.（3）The ground state properties of Rh_n（n=6,7）clusters and the electronic properties of systems of some small molecules（H₂,O₂,N₂,NO,CO,NO₂,CO₂,N₂O）adsorbed on Rh_n（n=6,7）clusters are systematically investigated by using DFT calculations.The results show that the symmetry of the ground state structure of Rh6 clusters is Oh and there is no low energy isomer;But there is competition in the ground state structure of Rh7 clusters.Physical adsorption of gases on Rh6 clusters are O₂、N₂、NO、CO and CO₂;Physical adsorption of gases on A of Rh7 clusters are O₂、N₂、CO、CO₂、NO;Physical adsorption of gases on B of Rh7 clusters are H₂、O₂、N₂、CO、CO₂、NO、NO₂.The chemical reaction of the eight kinds of gases in the three different structures is N₂ O.As far as physical adsorption is also concerned,Ead（NO）>Ead（O₂）≈Ead（NO₂）≈Ead（CO）>Ead（N₂）≈Ead（CO₂）>Ead（H₂）.There have the charge transfer in the interaction with eight kinds of gases.The number of charge transfer owing to whether the gas molecules contain O elements.It can get more electrons if the presence of O elements in the gas.As for the physical adsorption,the charge transfer: q（CO₂）≈ q（O₂）> q（NO₂）> q（NO）≈ q（CO）> q（N₂）> q（H₂）。...