By means of vibrational spectroscopy and density functional theory (DFT), we investigate CO adsorption on phosphorene-based systems. We find stable CO adsorption at room temperature on both phosphorene and bulk black phosphorus. The adsorption energy and vibrational spectrum are calculated for several possible configurations of the CO overlayer. We find that the vibrational spectrum is characterized by two different C–O stretching energies. The experimental data are in good agreement with the prediction of the DFT model and reveal the unusual C–O vibrational band at 165–180 meV, activated by the lateral interactions in the CO overlayer.

Graphene/Ni(110) has been studied by time-resolved X-ray photoelectron spectroscopy and near-edge X-ray absorption fine structure. The C 1s core level shows a splitting typical of periodically rippled interfaces. The analysis of the C K-edge reveals that the interface states previously observed for graphene/Ni(111) are suppressed in graphene/Ni(110). This suppression is due to the reduced hybridization of the Dirac-cone electrons in graphene with the d-bands of the (110)-oriented nickel contacts. Our results show that, contrary to commensurate growth of graphene on Ni(111), epitaxially grown graphene on Ni(110) behaves as a quasi-freestanding sheet, as the lattice mismatch gives rise to a moiré reconstruction.

By analyzing phonon dispersion, we have evaluated the average Young's modulus and Poisson's ratio in graphite and in graphene grown on Ru(0001), Pt(111), Ir(111), Ni(111), and BC₃/NbB₂(0001). In both flat and corrugated graphene sheets and in graphite, we find a Poisson's ratio of 0.19 and a Young's modulus of 342 N/m. The unique exception is graphene/Ni(111), for which we find different values because of the stretching of C-C bonds occurring in the commensurate overstructure (0.36 and 310 N/m for the Poisson's ratio and Young's modulus, respectively). Such findings are in excellent agreement with calculations performed for a free-standing graphene membrane. The high crystalline quality of graphene grown on metal substrates leads to macroscopic samples with high tensile strength and bending flexibility for use in technological applications such as electromechanical devices and carbon-fiber reinforcements.