Dual-Route Hydrogenation of the Graphene/Ni Interface

Abstract

Nanostructured architectures based on graphene/metal interfaces might be efficiently exploited in hydrogen storage due to the attractive capability to provide adsorption sites both at the top side of graphene and at the metal substrate after intercalation. We combined in situ high resolution x-ray photoelectron spectroscopy and scanning tunneling microscopy with theoretical calculations to determine the arrangement of hydrogen atoms at the graphene/Ni(111) interface at room temperature. Our results show that at low coverage H atoms predominantly adsorb as monomers and that chemisorption saturates when ∼25% of the surface is hydrogenated. In parallel, with a much lower rate, H atoms intercalate below graphene and bind to Ni surface sites. Intercalation progressively destabilizes the C-H bonds and triggers the release of the hydrogen chemisorbed on graphene. Valence band and near edge absorption spectroscopy demonstrate that the graphene layer is fully lifted when the Ni surface is saturated with H. Thermal programmed desorption was used to determine the stability of the hydrogenated interface. Whereas the H atoms chemisorbed on graphene remain unperturbed over a wide temperature range, the intercalated phase abruptly desorbs 50-100 K above room temperature.

Unusual reversibility in molecular break-up of PAHs: the case of pentacene dehydrogenation on Ir(111)

“…In addition the possibility to govern the on-surface dehydrogenation process could represent a step towards the tailored fabrication of molecular 2D nanoarchitectures [31][32][33][34] distinct from graphene. 35 While it is true that dehydrogenation reversible reactions have already been observed for small, single C-atom containing molecules, to our knowledge no such observation has been made for larger hydrocarbons. Zaera reported indeed a reversible dehydrogenation reaction of methyl iodide (CH 3 I) taking place on Pt(111) 36 .…”

“…In addition the possibility to govern the on-surface dehydrogenation process could represent a step towards the tailored fabrication of molecular 2D nanoarchitectures 31–34 distinct from graphene. 35…”

Electronic and Magnetic Diversity of Graphone/Graphene Superlattices

“…The hydrogen-functionalized multilayer graphene has been fabricated in the experiments and it exhibited the ferromagnetism because of H atoms adsorbed on the sole sublattice of graphene. − The graphone/graphene bilayer has been fabricated in the experiments . The above-room temperature ferromagnetism of H-functionalized graphene is found in the experiments .…”

“…Recently, twisted graphene layers with a magic angle are found with the exotic physical properties such as the superconductivity, correlated insulator, and density waves. − The lack of intrinsic magnetism of 2D materials such as graphene, MoS 2 , and black phosphorene has motivated many efforts to explore 2D magnetic materials. The rising of intrinsic magnetic semiconductors CrI 3 and Cr 2 Ge 2 Te 6 has pushed the research of two-dimensional materials to a newer and higher stage. − Actually, the graphene itself can turn into magnetic materials through defects and atomic functionalization. − …”

Intrinsically Honeycomb‐Patterned Hydrogenated Graphene

“…[6] One-thirdhydrogenated graphene (OTHG) has also been fabricated and found to exhibit anisotropic electronic properties. [7] By now, a large assortment of hydrogenated forms of graphene (HGr) with different carbon-to-hydrogen (C/H) ratios have been predicted [2,5,8] or fabricated [7,[9][10][11][12][13][14][15][16][17][18][19][20] . It has been found that the C/H ratio can be used to tune the band gap.…”