Carbonylated graphene as a new graphene chemical derivative and its application in gas sensing

Progress in the study of graphenes has led to appearance of a new subclass of nanocarbon materials - chemically modified graphenes (CMG). CMGs, decorated with certain types of functional groups, demonstrate new electronic, optical and chemical properties, thus opening up new possibilities for the use of graphene-based materials in electrochemical and sensing applications. We present our results on the synthesis, analysis of physical properties and application of one of these derivatives - carbonylated (C-ny) graphene. Carbonylated graphene was obtained by a liquid-phase treatment of graphene oxide using sodium silicate under moderate heating. As a result of this process, the material structure became represented by holey graphene layers with a high density of small-sized holes. Functional composition has also changed. Most of the basal and edge-located groups were eliminated. At the same time, the concentration of carbonyl groups increased. Presented synthesis method allows to control the concentration of carbonyl groups, reaching concentrations from 3 up to 9 at.%. Detailed study of C-ny graphene using various synchrotron techniques and revealed that functionalization led to significant changes in the C-ny graphene's electronic structure. Particularly, only partial restoration of the π conjugated network is revealed, while new local states appeared in the graphene valence band near the Fermi level related to the molecular orbitals of the covalently attached carbonyls. This results in the changes of the materials work function value and high resistance of the material of several hundreds of MΩ. This value is too high for the application in electronic devices. However, it was found that C-ny graphene can be used as base-material for gas-sensitive chips, which can operate and regenerate at room temperature with a sensitivity up to hundreds ppm. Moreover, chemoresistive biosensors for viral detection can be further formed using C-ny graphene owing to both its electrical properties and chemical reactivity through non-covalent bonding of the presented carbonyls with organic species. The presented work was financially supported by the Russian Foundation for Basic Research (Project No. 18-29-19172).