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 sp(2) to the sp(3) bond symmetry, which propagates through the graphene layers, resulting in interlayer carbon bond formation. The structure is stabilized through the termination of interfacial sp(3) carbon atoms by the substrate. The structural transformation occurs as a consequence of high adsorption energy.