  Studies of the structural, electronic, and optical characteristics of the
interfaces between graphene and ZnO polar surfaces is carried out using
first-principles simulations. At the interface, a strong van der Waals force is
present, and because of the different work functions of graphene and ZnO,
charge transfer takes place. Graphene's superior conductivity is not impacted
by its interaction with ZnO, since its Dirac point is unaffected despite its
adsorption on ZnO. In hybrid systems, excited electrons with energies between 0
and 3 eV (above Fermi energy) are primarily accumulated on graphene. The
calculations offer a theoretical justification for the successful operation of
graphene / ZnO hybrid materials as photocatalysts and solar cells. ZnO
semiconductor is found to be a suitable material with modest band gap, ($\sim$
3 eV), having high transparency in visible region and a high optical
conductivity.
