Unraveling the strong coupling between graphene/nickel interface and atmospheric adsorbates for versatile realistic applications

Abstract

During many synthesis processes and promising applications of Ni-based metals coated with graphene (Gr) layers, the Gr/Ni interface closely contacts with various environmental species, especially the ubiquitous atmospheric ones (e.g., H, O, OH, and H2O). In this work, the binding strength of Gr/Ni interface, stability of atmospheric adsorbates on both monolayer and multilayer Gr coatings, and adsorbate–interface coupling are investigated using density-functional-theory calculations, where the interface state, adsorbate type, and adsorption location on Gr coating are found to be the key factors jointly determining the adsorbate–interface coupling. The dramatic adsorbate–interface coupling occurs with the covalent adsorbates (O, H, and OH) on monolayer Gr coating or the buffer Gr layer in multilayer coating, and the covalent adsorbate–Gr bonding results in unpaired π electrons that turn to enhance both the interface binding and adsorbate stability. The physical H2O adsorbate has a negligible effect on the structure and binding strength of the Gr/Ni interface, while the electrostatic mechanism affects the posture of H2O adsorbate at different locations. In addition, we also find that the strong chemical interface binding can induce a structural transition for the O adsorbate from its usual bridge configuration into the top one.