Theoretical Studies On The Binding Of Metal Atom Clusters And The Perfect Or Defective Graphene

Graphene is one of the most important carbon-based materials. It is of great potential application in catalyst carrier for its huge surface area and superb chemical stability. To gain an insight into the interaction between metal and graphene material, we have studied the stable binding configurations, binding energy, chemical bondings, electron structres and so on using periodic supercell models based on density functional theory and general gradient approximation. The main results are listed as follows:1. The binding strength of IB group metal single and double atomic clusters on premitive or N-doped graphene has been carefully studied. The results indicated that Physical or very weak chemical adsorption was got when metal atomic clusters adsorbing on PG or NG1. The binding abilities of metal single atom and substrates are following this order:Cu>Au>Ag. The Mulliken population analysis indicated that metal single atoms were electropositive while double atom clusters were electronegative after interacting with pyridine N-doped graphene. It was demonstrated that Cu atom bonded with three atoms with dangling bonds while Au atom bonded with two of them in pyridine N-doped graphene by the density of states and orbital analysis.2. In this section, we investigated the distribution of N dopant atoms in various substrates with different N-doping concentrations and then alone Pt atom adsorption on these substrates were researched. Our calculation shows that the N dopant atoms tend to be in para position in N-doped graphene and alone Pt atom is favorable to be adsorbed on C-C bridge site which is surrounding the N dopant atoms. The enhancement of Pt 6s and C 2p orbitals bonding interation improves the ability of Pt atom adsorption on N-doped graphene.3.Comparing interaction of Ptn(n=1～3) clusters and perfect graphene or N-doped graphene with high N-doping concentration, we mainly pay attention to the different stable binding structures and corresponding binding energies. The calculated results indicated that graphene with high N-doping concentration could also enhance the interaction between Ptn(n=1～3) clusters and graphene substrates. In addition, we found the Pt atom in Ptn(n=1～3) would not bind with N atom in NG substrates. This means pockets of higher density N-doping could serve as a barrier to stop Pt atom migration on the substrates to form large, less active catalyst sites. Besides, Ptn(n=1～3) tends to bind with the substrates in vertical way, not parallel to the substrates.