▎ 摘　　要

A large out-of-plane piezoelectricity can be induced in graphene by carbon substitution. Several simple substitutions are considered where C atoms are replaced by heavier group-IV elements (Si, Ge, and Sn). A more complex functionalization (namely, pyrrolic N-doped graphene) is also investigated where different functional groups, such as F, Cl, H3C, and H2N, are studied. Piezoelectric and elastic response properties of all systems are determined quantum mechanically at the ab initio level of theory. A rationalization of the physical and chemical parameters which most affect the out-of-plane piezoelectricity of functionalized graphene is reported, which reveals the dominant character of the nuclear over electronic contribution. The combination of an out-of-plane symmetry breaking defect and a soft infrared-active phonon mode, with a large cell-deformation coupling, is shown to constitute the necessary prerequisite to response into functionalized graphene. induce a large out-of-plane piezoelectric response into functionalized graphene.