Sol-gel autocombustion synthesis of graphene/cobalt magnetic nanocomposites.

Here we describe a versatile new strategy for producing graphene/cobalt magnetic nanocomposites by combining the sol-gel method and autocombustion. We used graphene oxide (GO), cobalt nitrate and citric acid as starting materials and prepared a dry gel of them through a routine sol-gel approach. After the autocombustion was activated at 300 degrees C in a tube furnace under an argon atmosphere, reducing agents such as H2 and CH4 were produced and then in situ reduced GO and cobalt nitrate to get graphene/cobalt magnetic nanocomposites. X-ray photoelectron spectroscopic and X-ray powder diffraction analysis showed that the nanoparticles loaded on graphene are cobalt but not cobalt oxide. Transmission electron microscopy and scanning electron microscopy revealed that cobalt nanoparticles, with an average diameter of -10 nm, were homogeniously deposited on the surface of graphene. Further more, other metal nanoparticles such as Ni, Cu, Ag and Bi can also be loaded on graphene using the same method.