Crystalline multilayer graphene nanoflakes synthesized by catalytic chemical vapor deposition using reduced nanostructured hematite as catalyst precursor and 1,2-dichlorobenzene and benzylamine mixture as carbon source

Abstract

Carbon solubility in the catalyst for the growth of graphene-type nanomaterials is an essential issue for their large-scale fabrication. Iron compounds are fundamental catalysts for the synthesis of carbon materials. The carbon solubility of ferrite (α-Fe) is ∼0.1% at 700 °C, which is enough to promote the growth of graphene nanomaterials. In this work, we synthesized crystalline multilayer graphene flakes (MLGFs) by a two-step catalytic chemical vapor deposition method using an α-Fe catalyst derived from the reduction of nanostructured hematite at 950 °C under an Ar–H2 environment. In the first step, nitrogen-doped multi-walled carbon nanotubes were synthesized by a benzylamine-ferrocene mixture at 850 °C and oxidized at 620 °C in air. In the second step, the reduced nanostructured hematite was exposed to a mixture of a 1:9 benzylamine-1,2- dichlorobenzene at 950 °C. Raman spectroscopy confirmed the presence of MLGFs with a G band and a significant 2D band intensity. The results of the thermogravimetric analysis show that the maximum oxidation rate was at 643.5 °C. Additional functional density calculations were performed considering graphene growth on the oriented (110) α-Fe surface. This work reasserts the possibility of using alternative carbon sources for graphene growth.