Researchers from Rice University managed to develop a new hybrid material that combines carbon nanotubes (CNTs) with graphene. The CNTs rise like towers from the graphene - up to 120 microns in height. This material has a massive surface (over 2,000 square meters per gram of material), which will be great for energy storage supercapacitors and other applications. Just to compare, a house on an average plot with the same aspect ratio would rise into space.
The nanotubes do not simply "sit" on the graphene - they are part of it as they share the atoms (the bonds between them are covalent). To develop this material, the researchers grew graphene on metal (copper) and then the CNTs were grown on the graphene. The electrical contact between the nanotubes and the metal electrode is ohmic. That means electrons see no difference, because it's all one seamless material.