Nano-scale corrugations in graphene: A density functional theory study of structure, electronic properties and hydrogenation

Graphene rippled at the nanoscale level is gathering attention for advanced applications, especially in the field of nanoelectronics and hydrogen storage. Convexity enhanced reactivity toward H was demonstrated on naturally corrugated graphene grown by Si evaporation on SiC, which makes this system a platform for fundamental studies on the effects of rippling. In this work, we report a density functional theory study on a model system specifically designed to mimic graphene on SiC. We first study the supercell geometry and configuration that better reproduce the corrugated monolayer. The relatively low computational cost of this model system allows a systematic study of the dependence of stability, structure, and electronic properties of graphene subject to different levels of stretching and corrugation. The most representative structure is then progressively hydrogenated, imitating the exposure to atomic hydrogen, and stability, structural and electronic properties are evaluated as a function of hydrogenation. Our results quantitatively reproduce the measured evolution of electronic properties as a function of hydrogenation, offering the possibility of evaluating the coverage by means of STS measurements. The dependence of hydrogen binding energy on coverage extends our previous results on reactivity of corrugated graphene, including the effect of H clustering. This work reports quantitative results directly comparable with experimental measurements performed on epitaxial graphene on SiC and reveals the quantitative interplay between local structure, electronic properties and reactivity to hydrogen, which could be used to design devices for flexible nanoelectronics and for H storage.