▎ 摘　　要

Atomic structure of Ti and Ti-4 cluster on the surface of graphene are studied by the density functional theory and nonequilibrium Green's function formalism. The most stable configurations for Ti and Ti-4 adsorbed on the graphene surface are investigated, and the binding energies corresponding to the configurations are calculated. We found that the Ti-4 clusters can strongly interact with pristine graphene surface, and the interaction can be further enhanced when structural vacancies are introduced onto the graphene surface. Electronic properties of metal/graphene composites are also presented to show their highly spin polarized behaviors. The transport properties of systems are dependent on the applied bias voltage. Our results also indicate that the Ti-4/graphene composite is a simple and typical model to study the interactive effects of metal clusters absorbed on graphene. The results of this work could help to design novel devices such as nanoelectrodes and magnetic sensors based on graphene. (C) 2012 Elsevier B. V. All rights reserved.