2025/04/14 by Apponi, Alice, Castellano, Orlando, Paoloni, Daniele +5
#FOS: Physical sciences #Materials Science (cond-mat.mtrl-sci)
paper · doi:10.48550/arxiv.2504.10238
A thorough spectroscopic characterisation of highly hydrogenated monolayer graphene trasferred on TEM grids is herein reported. The graphene hydrogenation has the effect to distort the sp2 arrangement of carbon atoms in the lattice toward a sp3-like coordination, through the breaking of the π-bonds, as determined by X ray photoelectron spectroscopy of the C 1s core level. The hydrogen bonding was found to be favoured for a more distorted graphene lattice. Indeed, a 100% sp3-saturation - the highest ever achieved - was observed after the hydrogenation of a sample with more pristine sp3-like deformed bonds, while the flatter, more sp2-arranged, sample reached a 59% sp3-saturation. Electron energy loss spectroscopy confirmed the photoemission result showing the π-plasmon excitation quenching, in the totally hydrogenated sample, and significant reduction, for the other one. High loading levels of hydrogenation were also witnessed by the opening of a wide optical band gap (6.3 and 6.2 eV). The observation of the C-H stretching vibrational mode is also reported, as a direct footprint of graphene hydrogenation. Finally, valence band measurements of the 59% saturated sample suggest the coexistence of one-side and two-side hydrogenation morphologies.