Large-size single crystal graphene grains are important since grain boundaries are believed to markedly degrade its quality and properties.However,graphene films prepared so far are usually stitched together from nanometer to micrometer-size grains.At the same time,integration of individual two-dimensional graphene into macroscopic structures is essentially important for many applications of graphene.But graphene-based composites from chemically-derived graphene sheets suffer from poor electrical conductivity.First,the growth of graphene by CVD in a reasonably large quantity [1] and the direct synthesis of a three-dimensional interconnected graphene macrostructure by template-directed CVD [2],which is called graphene foam (GF),were achieved.This porous graphene bulk material consists of an interconnected network of graphene,is flexible,and has outstanding electrical and mechanical properties.Second,we developed an ambient pressure CVD to synthesize high quality graphene films and millimeter-size single crystal graphene grains,and a bubbling method to transfer these graphene films,which is nondestructive to the Pt foils [3].The Pt foils can be repeatedly used for graphene growth with no limit.The single-crystal graphene with large-size grains on repeatably usable Pt substrates has high crystallinity and high electrical mobility.