Interlayer Carbon Bond Formation Induced by Hydrogen Adsorption in Few-Layer Supported Graphene

We report on the hydrogen adsorption induced phase transition of a few layer graphene (1 to 4 layers) to a diamondlike structure on Pt(111) based on core level x-ray spectroscopy, temperature programed desorption, infrared spectroscopy, and density functional theory total energy calculations. The surface adsorption of hydrogen induces a hybridization change of carbon from the $s{p}^2$ to the $s{p}^3$ bond symmetry, which propagates through the graphene layers, resulting in interlayer carbon bond formation. The structure is stabilized through the termination of interfacial $s{p}^3$ carbon atoms by the substrate. The structural transformation occurs as a consequence of high adsorption energy.