Enhancing graphene reinforcing potential in composites by hydrogen passivation induced dispersion

To take full advantages of the structural uniqueness and exceptional properties of graphene as reinforcement in composites, harvesting well-dispersed graphene is essential. On the other hand, it is challenging to achieve simultaneously high stiffness, strength and toughness in engineered materials because of the trade-off relations between these properties. Here we demonstrate that the graphene reinforcing potential can be significantly enhanced through the excellent dispersion of graphene sheets in the matrix material and the strong graphene-matrix bonding by the coupled hydrogen passivation and ultrasonication technique. The fabricated graphene/epoxy composites exhibit simultaneously remarkable increase in elastic modulus, fracture strength, and fracture energy. We found that the inlet hydrogen atoms in the hydrogen passivation serve as a source of the second atoms to terminate the C dangling bonds and form more stable C-H bonds, separating graphene flakes and promoting the binding with the matrix material.