Adjusting acetylene gas flow to grow a spheroidal graphene film with controllable layer number and lattice defects

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Spheroidal graphene film (SGF) is of importance for the spatial sensor matrix applications due to its large specific surface area and more chemical modification sites. It is difficult to in-situ grow the SGF on the desired substrate, specifically, the control of the number of layers and lattice defects of SGF is difficult. In this work, the SGF is grown in-situ on a cemented carbide surface with controllable layer number and lattice defects. The Co, a binder phase in cemented carbide, was used as a catalytic metal; amorphous SiC (a-SiC) film was used as a carbon source on the surface of the cemented carbide and catalytic reaction occurred under the annealing condition. The controllable preparation of a number of layers and lattice defects of graphene was achieved by controlling the flow rate of acetylene gas during the deposition of the a-SiC film. It was found that the acetylene gas flow rate can directly control the C atom content of the interfacial layer. With the increase of the content of C atoms, the lattice defects of the resulting graphene tend to decrease, while the number of layers of SGF tends to increase. The reaction mechanism of growth of SGF is discussed. The content of C atom may induce the change of the phase composition of the interfacial layer, which acts as a constituting element of the graphene film. As a result, the content of C atoms is in close relationship with the number of layers and lattice defects of the SGF.