Investigation of NH3 and H2 adsorption on Ptn(n = 2-15, 18, 22, 24) clusters by using density functional theory

The adsorption of NH3 and H2 molecules on Ptn clusters is investigated by density functional theory calculations within generaliz ed gradient approximation. The size dependence of adsorption energy, highest occupied molecular orbital, lowest unoccupied molecular orbital, magnetization, and bond length values are investigated. A strong interaction is found between Pt and N atoms. It is surprisingly observed that NH3 dissociation occurs at Pt14 cluster. We found that H2 molecule dissociates at different adsorption sites for all clusters except Pt3 cluster. Each of H atom seems to prefer to bound different Pt atoms. We see that d orbital of Pt is dominant near the Fermi level in NH3 and H2 adsorbed Ptn clusters. Metallic and conductivity properties of Ptn clusters change with adsorption of NH3 and H2 molecules. NH3 adsorbed Pt2 cluster can show half metallic properties. HOMO-LUMO gap (HLG) values for NH3 and H2 adsorbed Ptn clusters are evaluated. The results also imply charge transfer from Pt to H atoms in H2 adsorbed Ptn clusters and a polarization between Pt and N atoms in NH3 adsorbed clusters. These results also comply with Löwdin analysis.