Al_nPt Clusters And CO Oxidation On The Al₁₂X （X=Ni, Pd, Pt,Ti,Zr） Clusters

With the single-component clusters gradually in-depth study,mixed doped clusters gradually become the cluster physics topicsat the forefront in recent years. Nanomaterials which are performedby nanometer-size clusters show an excellent mechanicalproperties, magnetism properties, catalytic and thermal properties.And the most important catalysts in the chemical industry are thetransition metal alloy. In a variety of metal materials, due to thelarge work function, very stable chemical properties, goodelectrical properties, therefore, platinum in the metal alloy has awide application prospect. A lot of researches have been carriedout on platinum doped alloy material of the other metal elementsand clusters. This chapter we calculate the geometries andelectronic properties of neutral AlnPt (n=1-15) clusters in Gaussian03procedure, using DFT/B3LYP method. The growth patten for AlnPt clusters is that the Pt atom substituted the surface atomof the Aln+1clusters for n<13. Starting from n=13, the Pt atomcompletely falls into the center of the Al-frame. The Pt atomsubstituted the center atom of the Aln+1clusters to form thePt-encapsulated Alngeometries for n>13. We also find that theimpurity Pt atom causes local structural distortion due to differentatomic radii and different bonding characteristics. The bindingenergy, second-order energy differences, dissociation energy,Ionization potentials, electron affinities, HOMO-LUMO energy gap,in comparison with pure aluminum clusters have beensystematically investigated, and we could conclude that: theclusters with atom number of2,7and11exhibit higher stability.Due to the rapid development of modern industry, CO toxic gasemissions is gradually increasing, which is an urgent need todevelop new catalysts for the catalytic oxidation of CO gas in recentyears. Because of their unique properties, nanoparticle catalystsare more and more concerned, this paper the equilibriumgeometries of Al12X (X=Ni, Pd, Pt, Ti, Zr) cluster were systematicallystudied on the basis of density functional theory with generalizedgradient approximation. Al, C, O atoms use6-31G*basis sets and Ni,Pd, Pt, Ti, Zr atoms use LANL2DZ basis sets. To gain insights into high catalytic activity we use the CO oxidation as a benchmarkprobe. Firstly, we study the geometic structure of Al12X (X=Ni, Pd, Pt,Ti, Zr), CO and O2binding on Al12X (X=Ni, Pd, Pt, Ti, Zr) clusters andCO oxidation. We design two kinds of reaction processes:bi-molecular LH-mechanism and Tri-molecular LH-mechanism.Bi-molecular LH-mechanism procee via two-step: CO+O2â†'CO2+Oand CO+Oâ†'CO2. Two CO oxidation mechanisms of two CO2molecules as product have been simulated. For the later mechanism,the key step is the O-O bond scission in the OCOO*intermediate,which is significantly accelerated due to the attack of theneighboring CO molecule. The calculated barriers for the laterreactions are lower compared with the former reaction. Detailedreaction paths corresponding to this case are calculated. Our studysuggests that CO oxidation on Al12X (X=Ni, Pd, Pt, Ti, Zr) clusters belikely to occur at the room temperature. Moreover, Al12X (X=Ti, Zr)cluster is more effective catalysts.