▎ 摘　　要

Two-dimensional (2D) carbon sheets exhibit excellent physical properties and significant application potentials stemmed from their ultra-thin structures. In this study, we investigate the structural stability, mechanical properties, electronic structure and carrier mobility of an all-sp(2) hybridized carbon sheet with tetragon, hexagon and dodecagon rings (named as THD-graphene). This 2D semiconductive carbon allotrope exhibits excellent mechanical properties as its plane stiffness can be up to 78% that of graphene. Large natural dodecagon hole enables some small gas molecules to pass through it and their feature energy barrier is different. When some small molecules approach the dodecagon hole, the scattering of thermal electrons from the acoustic phonons will be enhanced due to the interaction between THD-graphene and molecule and thus the carrier mobility decreases. Distinct change of mobility change makes it possible to utilize THD-graphene to detect small gas molecules. (C) 2017 Elsevier B.V. All rights reserved.