▎ 摘　　要

We demonstrated the chemical-vapor sensing properties of graphene and carbon nanotubes (CNTs) by comparing their performances based on the two-dimensional exposure ratio. In order to implement the gas sensing, two kinds of sensors were properly prepared via the highly oriented pyrolytic graphite (HOPG) and CNT-dispersing methods, which cover different sensing area each other. Although the area of graphene is three times smaller than that of CNTs, the excellent sensing performance of graphene in the various concentration of the target gas is shown in terms of the sensitivity, the reactivity, and response time. We concluded this experimental result by focusing on the surface to volume ratio. (C) 2012 The Japan Society of Applied Physics