Valence Band Structure Engineering in Graphene Derivatives

Engineering of the 2D materials' electronic structure is at the forefront of nanomaterials research nowadays, giving an advance in the development of next-generation photonic devices, e-sensing technologies, and smart materials. Herein, employing core-level spectroscopy methods combined with density functional theory (DFT) modeling, the modification of the graphenes' valence band (VB) upon its derivatization by carboxyls and ketones is revealed. The appearance of a set of localized states in the VB of graphene related to molecular orbitals of the introduced functionalities is signified both experimentally and theoretically. Applying the DFT calculations of the density of states projected on the functional groups, their contributions to the VB structure are decomposed. An empirical approach, allowing one to analyze and predict the impact of a certain functional group on the graphenes' electronic structure in terms of examination of the model molecules, mimicking the introduced functionality, is proposed and validated. The interpretation of the arising states origin is made and their designation, pointing out their symmetry type, is proposed. Taken together, these results guide the band structure engineering of graphene derivatives and give a hint on the mechanisms underlying the alteration of the VB structure of 2D materials upon their derivatization.

Automated summary

This study examines the engineering of 2D materials' electronic structure, focusing on how the introduction of functional groups affects the valence band. Core-level spectroscopy methods and density functional theory modeling are used to reveal the modification of graphene's valence band upon derivatization, with a proposed empirical approach to analyze and predict these effects. The results provide insight into band structure engineering of graphene derivatives and the mechanisms underlying the alteration of 2D materials' valence band structure upon derivatization.