Nucleation of Graphene Layers On Magnetic Oxides: Co_3O_4(111) and Cr_2O_3(0001) from Theory and Experiment
John Beatty, Tao Cheng, Yuan Cao, M. Sky Driver, William A. Goddard III, Jeffry A. Kelber
Abstract
We report direct grown strongly adherent graphene on Co_3O_4(111) by Carbon molecular beam epitaxy (MBE) at 850 K and DFT findings that the first graphene layer is reconstructed to fit the Co_3O_4 surface, while subsequent layers retain normal graphene structure. This adherence to the Co_3O_4 structure results from partial bonding of half the carbons to top oxygen of the substrate. This structure is validated by X-ray photoelectron spectroscopy and low energy electron diffraction studies, showing layer-by-layer graphene growth with ~ 0.08 electrons/carbon atom transferred to the oxide from the first graphene layer, in agreement with DFT. In contrast, C MBE on Cr_2O_3(0001) yields only graphite formation at 700 K, with C desorption above 800 K. For Cr_2O_3 DFT finds no strong bonding to the surface, with charge transfer is away from the oxide. Thus strong graphene-to-oxide charge transfer aids nucleation of graphene on incommensurate oxide substrates.
Group Members
Beatty, J., Cheng, T., Cao, Y., Driver, M. S., III, W. A. G., & Kelber, J. A. (2016). Nucleation of Graphene Layers On Magnetic Oxides: Co_3O_4(111) and Cr_2O_3(0001) from Theory and Experiment. *J. Phys. Chem. Lett.*, *2017*(8), 188-192.