쉐브론타입 그래핀 나노리본에서의 원자흡착에 관한 제일원리계산

Abstract

Ab initio calculations of atomic adsorption on the zigzag and the chevron type graphene nanoribbons are presented. First, atomic hydrogen binding on zigzag graphene nanoribbons (ZGNRs) were studied. It was found that the adsorption path starts from the edges of ZGNR and moves into the inner part of ZGNR. The possibility of the hydrogen spillover phenomenon was also investigated. It was found that adsorption energies at the carbon atoms belonging to particular sublattice type are smaller than those in other sublattice and also than the bond energy of a hydrogen molecule. These low adsorption energies at particular sublattice will act as potential barriers and we conclude that the spillover is hard to occur. Next, the electronic and adsorption properties of chevron type graphene nanoribbons were studied. As the width of the chevron nanoribbons are increased, our calculations show three types of pattern in the band gap, which is similar to the case of armchair-type graphene nanoribbons. It was found that the alkali metal (Li, Na and K) adsorption on particular sites of the hexagon center in the chevron-type GNR induces magnetic moment of about 1μB per unit cell. We calculated the adsorption energy of hydrogen molecule on these alkali metals dispersed in the chevron-type graphene nanoribbon and found that it is comparable to that in the armchair GNRs.