The derivatization of graphene to engineer its band structure is a subject of significant attention nowadays, extending the frames of graphene material applications in the fields of catalysis, sensing, and energy harvesting. Yet, the accurate identification of a certain group and its effect on graphene’s electronic structure is an intricate question. Herein, we propose the advanced fingerprinting of the epoxide and hydroxyl groups on the graphene layers via core-level methods and reveal the modification of their valence band (VB) upon the introduction of these oxygen functionalities. The distinctive contribution of epoxide and hydroxyl groups to the C 1s X-ray photoelectron spectra was indicated experimentally, allowing the quantitative characterization of each group, not just their sum. The appearance of a set of localized states in graphene’s VB related to the molecular orbitals of the introduced functionalities was signified both experimentally and theoretically. Applying the density functional theory calculations, the impact of the localized states corresponding to the molecular orbitals of the hydroxyl and epoxide groups was decomposed. Altogether, these findings unveiled the particular contribution of the epoxide and hydroxyl groups to the core-level spectra and band structure of graphene derivatives, advancing graphene functionalization as a tool to engineer its physical properties.

Monodisperse carbon nanodots (MCNDs) having an identical composition, structure, shape and size possess identical chemical and physical properties, making them highly promising for various technical and medical applications. Herein, we report a facile and effective route to obtain monodisperse carbon nanodots 3.5 ± 0.9 nm in size by thermal decomposition of organosilane within the pores of monodisperse mesoporous silica particles with subsequent removal of the silica template. Structural studies demonstrated that the MCNDs we synthesized consist of ∼7–10 defective graphene layers that are misoriented with respect to each other and contain various oxygen-containing functional groups. It was demonstrated that, owing to their identical size and chemical composition, the MCNDs are formed via coagulation primary aggregates ∼10–30 nm in size, which are, in turn, combined into secondary porous spherical aggregates ∼100–200 nm in diameter. The processes of coagulation of MCNDs and peptization of their hierarchical aggregates are fully reversible and can be controlled by varying the MCND concentration or the pH value of the hydrosols. Submicrometer spherical aggregates of MCNDs are not disintegrated as the hydrosol is dried. The thus obtained porous spherical aggregates of MCNDs are promising for drug delivery as a self-disassembling container for medicinal preparations.