▎ 摘　　要

In this article, we demonstrated a method to synthesize graphene films at low temperature via a mild radical-coupling reaction. During the deposition process, with the effectively breaking of the C-Br bonds of hexabromobenzene (HBB) precursors, the generated HBB radicals couple efficiently to form graphene films at the low temperature of 220-250 degrees C. In situ low-temperature scanning tunneling microscopy was used to provide atomic scale investigation of the graphene growth mechanism using HBB as precursor. The chemical structure evolution during the graphene growth process was further corroborated by in situ X-ray photoelectron spectroscopy measurements. The charge carrier mobility of the graphene film grown at low temperature is at 1000-4200 cm(2) V-1 s(-1), as evaluated in a field-effect transistor device configuration on SiO2 substrates, indicating the high quality of the films.