  We present a theoretical investigation on electron-phonon superconductivity
of honeycomb MX$_2$ layered structures. Where X is one element of the group-IV
(C, Si or Ge) and M an alkali or an alkaline-earth metal. Among the studied
composition we predict a $T_c$ of 7 K in RbGe$_2$, 9 K in RbSi$_2$ and 11 K in
SrC$_2$. All these compounds feature a strongly anisotropic superconducting
gap. Our results show that despite the different doping and structural
properties, the three families of materials fall into a similar description of
its superconducting behavior. This allows us to estimate an upper critical
temperature of about 20 K for the class of intercalated group-IV structures,
including intercalated graphite and doped graphene.
