Direct observation of ordered configurations of hydrogen adatoms on graphene.

Lin, Chenfang; Feng, Yexin; Xiao, Yingdong; Dürr, Michael; Huang, Xiangqian; Xu, Xiaozhi; Zhao, Ruguang; Wang, Enge et al. · Nano Lett · 2015

basic_science · Level V

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Abstract

Ordered configurations of hydrogen adatoms on graphene have long been proposed, calculated, and searched for. Here, we report direct observation of several ordered configurations of H adatoms on graphene by scanning tunneling microscopy. On the top side of the graphene plane, H atoms in the configurations appear to stick to carbon atoms in the same sublattice. Scanning tunneling spectroscopy measurements revealed a substantial gap in the local density of states in H-contained regions as well as in-gap states below the conduction band due to the incompleteness of H ordering. These findings can be well explained by density functional theory calculations based on double-sided H configurations. In addition, factors that may influence H ordering are discussed.