Continuous synthesis of nanostructured sheetlike carbons by thermal plasma decomposition of methane

Crumpled sheetlike carbons (SLCs) of a quasi-2-D graphite structure are continuously synthesized by thermal decomposition of methane using a dc plasma torch of hollow electrodes type operated in a reversed polarity mode. Field-emission scanning electron microscope images show that the products synthesized solely consist of a great number of individual SLCs, which are stacked with random orientation and interlaced each other with thin edges. The width and height of the nanostructured SLCs ranges from 100 to 150 nm, and the average thickness of their stacked graphene layers is estimated as 10 nm. The material analyses of X-ray diffraction and Brunauer-Emmett-Teller static gas adsorption indicate that the nanosized SLCs synthesized by this new method have excellent physicochemical properties, such as large specific surface area and highly graphitized structure with good crystallization, due to their corrugated sheetlike feature. The SLCs synthesized in such a 2-D graphitic structure would be more robust and versatile in their practical applications to hydrogen reservoir and electrical cell compared with other 1-D structures like carbon nanotubes and nanofibers. Although the detailed growth mechanism of SLCs in the thermal plasma environment is not ascertained, high-temperature atmosphere and strong directional flow of the thermal plasma inside the hollow electrodes of the torch may play an important role in the formation of nanostructured SLCs.