Theoretical Study Of The Adsorption Properties On The IB Group Elements' Surface

In present paper,the adsorption of Na atoms on silver surface,the adsorption and dissociation of ammonia on gold surface,the stable adsorption water and its dehydrogenated reaction on copper surface are investigated,respectively,by means of the density functional theory(DFT).The adsorption structures and the catalysis mechanisms are discussed in detail.1.DFT study on the adsorption of Na atoms on Ag(001)surfaceThe properties and geometries of Na atoms adsorption on Ag(001)surface were studied by means of the density functional theory(DFT)with the generalized gradient approximation(GGA).The adsorption energies,adsorption structures and density of states were calculated at 0.25 monolayer(ML).It was found that the hollow sites were the favorable adsorption sites with the lowest adsorption energies, which was in good agreement with the available experiments.The Fermi level of Ag increased due to electrons transferred from Na atoms to silver surface.This result indicated that the chemical activities of the Ag atoms using as catalyst increased.That is,Na is a promoter of catalyst.2.Adsorption and dissociation of ammonia on Au(111)surfacePeriodic density functional theory(DFT)calculations using plane waves had been performed to systematically investigate the stable adsorption amine and its dehydrogenated reaction on Au(111)surface.The equilibrium configuration including on top,bridge,hollow(fcc and hcp)site had been determined by relaxation of the system.Furthermore,the dissociation reaction of NH₃ on clean gold surface,as well as on the pre-covered oxygen atom and pre-covered hydroxyl group surface had been investigated.The results show that the dehydrogenated reaction energy barrier on the pre-covered oxygen gold surface is lower.The adsorbed O can promote the dehydrogenation of amine.Additionally,OH as the product of the NH₃ dissociation reaction participates in continuous dehydrogenation reaction,and the reaction energy barrier is lower.The results indicated that OH_ads play a key role in the dehydrogenated reaction on Au(111)surface.3.The stable adsorption water and its dehydrogenated reaction on Cu(100) surfaceWe perform a theoretical study about the stable adsorption water and its dehydrogenated reaction on Cu(100)surface.The equilibrium configuration including on top,bridge,hollow site had been determined by relaxation of the system.And the dissociation reaction of H₂O on clean copper surface,as well as on the pre-covered oxygen atom surface had been investigated.The results show that the dehydrogenated reaction energy barrier on the pre-covered oxygen copper surface is lower.The adsorbed O can promote the dehydrogenation of water.