Synthesis of graphene-coated carbon nanotubes-supported metal nanoparticles as multifunctional hybrid materials

This paper presents a methodology to produce hybrid multifunctional materials based on graphene coated-metal nanoparticles supported on carbon nanotubes (M-CNT). These hybrid materials were synthetized by impregnation-reduction-decoration (IRD) methodology. Supported metal nitrates, were decomposed and reduced in-situ with CNT. After the reducing procedure, metal particles were treated with methane pulses at temperatures between 700 °C and 900 °C to encapsulate them into a few graphene sheets. These hybrid materials were characterized through different analytical techniques. In-situ X-ray diffraction analysis showed that the decomposition of nitrates occurs simultaneously with an in-situ reduction of metal particles by utilizing CNT as reducing agent. The nucleation of these metal particles preferentially starts over carbon nanotubes defects. Synthetized metal nanoparticles are active for methane decomposition, allowing the deposition of carbonaceous materials and their crystallization as graphene layers covering the metal particles (between one and four graphene layers). Magnetic characterization suggests that these hybrid materials can be used for development of magnetic storage devices, while their multifunctional properties could be potentially exploited for development of a variety of catalysts and sensors.