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First-principles study of nickel reactivity under two-dimensional cover: Ni2C formation at rotated graphene/Ni(111) interface
- Source :
- Physical Review Materials. 5
- Publication Year :
- 2021
- Publisher :
- American Physical Society (APS), 2021.
-
Abstract
- Recent experiments indicate that the reactivity of metal surfaces changes profoundly when they are covered with two-dimensional (2D) materials. Nickel, the widespread catalyst choice for graphene (G) growth, exhibits complex surface restructuring even after the G sheet is fully grown. In particular, due to excess carbon segregation from bulk nickel to surface upon cooling, a nickel carbide (${\mathrm{Ni}}_{2}\mathrm{C}$) phase is detected under rotated graphene (RG) but not under epitaxial graphene (EG). Motivated by this experimental evidence, we construct different G/Ni(111) interface models accounting for the two types of G domains. Then, by applying density functional theory, we illuminate the microscopic mechanisms governing the structural changes of nickel surface induced by carbon segregation. A high concentration of subsurface carbon reduces the structural stability of Ni(111) surface and gives rise to the formation of thermodynamically advantageous ${\mathrm{Ni}}_{2}\mathrm{C}$ monolayer. We show the restructuring of the nickel surface under RG cover and reveal the essential role of G rotation in enabling high density of favorable C binding sites in the Ni(111) subsurface. As opposed to RG, the EG cover locks the majority of favorable C binding sites preventing the build-up of subsurface carbon density to a phase transition threshold. Therefore we confirm that the conversion of C-rich Ni surface to ${\mathrm{Ni}}_{2}\mathrm{C}$ takes place exclusively under RG cover, in line with the strong experimental evidence.
- Subjects :
- Materials science
Physics and Astronomy (miscellaneous)
Graphene
chemistry.chemical_element
02 engineering and technology
021001 nanoscience & nanotechnology
01 natural sciences
law.invention
Metal
Crystallography
Nickel
chemistry
Cover (topology)
law
visual_art
Phase (matter)
0103 physical sciences
Monolayer
visual_art.visual_art_medium
General Materials Science
Density functional theory
010306 general physics
0210 nano-technology
Carbon
Subjects
Details
- ISSN :
- 24759953
- Volume :
- 5
- Database :
- OpenAIRE
- Journal :
- Physical Review Materials
- Accession number :
- edsair.doi...........5edcc9706285414f77649d164ae9b26b