GRAPHITES AND GRAPHITE-LIKE MATERIALS AS MICROWAVE ACCEPTORS IN THE SYNTHESIS OF CARBON NANOSTRUCTURES

The work examines a number of solid carbon materials as acceptors that accumulate and convert microwave (MW) energy into thermal energy in the processes of synthesis of carbon nanotubes (CNTs) using the energy of microwave electromagnetic field. Graphites of different grades, thermally expanded graphite (TEG), graphite oxides, activated carbons, blast furnace coke, and carbon black have been studied as acceptors. Ferrocene was used as a metal catalyst precursor and carbon donor. The experiments were carried out by treating a mixture of acceptor and ferrocene in a 1 : 1 ratio with MW radiation of 2450 MHz frequency and 1 kW power. In most experiments, the process was accompanied by the formation of micro-arc discharges, leading to a rapid increase in the temperature of reaction mixture. The structure and morphology of the obtained carbon materials were investigated by electron microscopy and X-ray phase analysis. It was shown that experiments involving most of the studied microwave acceptors lead to the formation of carbon nanostructures, consisting mainly of multi-walled carbon nanotubes of characteristic “match” morphology with diameters in the range of 16-90 nm and few-layer graphene particles. In addition to the main components, the synthesis products contain carbon structures of a different morphology. Thus, in processes involving MKKZ graphite, bamboo-shaped CNTs and giant carbon tubes with a diameter of up to 450 nm and a length of up to several micrometers were identified. In the case of TEG, toroidal nanotubes were recorded, while in reactions with AG-3 activated carbon, the formation of CNTs with a helical morphology was observed. It was established that the studied acceptors demonstrate high microwave activity. It was found that the thermotransforming properties of graphite, TEG and coke are at the same level and significantly exceed those for active carbons and carbon black. For citation: Zaritovskii A.N., Kotenko E.N., Grishchuk S.V., Glazunova V.A., Volkova G.K. Graphites and graphite-like materials as microwave acceptors in the synthesis of carbon nanostructures. ChemChemTech [Izv. Vyssh. Uchebn. Zaved. Khim. Khim. Tekhnol.]. 2025. V. 68. N 3. P. 64-75. DOI: 10.6060/ivkkt.20256803.7098.