Heterogeneous nucleation and high orientation of ZnO nanorods on graphene

We report the realization of ZnO nanostructures on a graphene/SiO₂/Si substrate by using a facile precursor-template synthesis technique through catalyst-free, seed-layer-free chemical vapor deposition. Vertical growth on the graphene buffer layers resulted in highly-oriented ZnO nanorods due to heterogeneous nucleation of the bond-centered sites on graphene. This demonstrates that the morphology of the structures is sensitive to the graphene substrate owing to the strong ZnOgraphene interaction. The photoluminescence exhibited distinctive band-edge emission and defect emission. The defect emission could be largely eradicated by covering the graphene and decreasing the ZnO-graphene spacing.