We report the fabrication of flexible conductive graphene paper through a direct and gentle annealing process of graphene oxide paper. Thermal treatments at 700 ºC under argon or hydrogen atmosphere directly applied to parent graphene oxide paper lead to a significant removal of disruptive oxygen-containing functional groups, and to a considerable recovery of the sp 2 network structure. Detailed comparison of chemical and combined chemical-thermal treatments by scanning electronic microscopy (SEM), Raman, X-photoelectron spectroscopy (XPS) and conductivity measurements underline the high efficiency of the direct annealing process. The resulting highly reduced graphene oxide paper exhibits electrical conductivities as high as 8100 S/m representing an increase of 5 orders of magnitude with respect to the parent graphene oxide paper,

The effective removal of chemisorbed water in graphene oxide by oxidized carbon nanotubes via cooperatively strengthened OH···OC hydrogen bonds.

We report on the growth of non-stoichiometric nanocrystalline hydroxyapatite (nHAp) with a composition similar to natural bone by a wet-chemical in-situ precipitation route on carbon nanotubes (CNTs) with different degrees of oxygen functionalities and on graphene oxide (GO). Both, functionalization degree and morphology of CNTs and GO appear as critical parameters controlling the shape and crystallinity of the selfassembled nHAp nanoparticles in the corresponding composite materials. Crystalline nHAp nanoparticles with rod-like morphology were achieved for moderately oxidized 2 CNTs and for GO. On CNTs these grow along the CNT's axis while on GO they form a compact layer. In both cases enhanced nHAp integration onto the respective carbon support is obtained. In vitro bioactivity of the prepared composites exhibits a fast apatite biomineralization process, induced by the presence of nHAp. Depending on its crystalline size and dispersion degree remineralization of the apatite nanoparticles takes place through the inclusion of PO 4 3-and CO 3 2-by ion exchange. Importantly, during the stage of bioactivity the integration degree of nHAp nanoparticles on the carbon nanostructures alters with time, evidencing the potential of GO as valuable bioceramic support material.

We investigated the effect of catalyst design on the synthesis of multi-walled carbon nanotubes (MWCNTs) by chemical vapour deposition (CVD). A set of highly active supported sol-gel Co-Mo/MgO and Ni-Mo/MgO catalysts was prepared systematically modifying the calcination temperature. First, the evolution of catalysts' crystallographic phases and their morphology were studied by X-ray diffraction (XRD), Raman spectroscopy, scanning electron (SEM) and transmission electron (TEM) microscopy. Second, the catalysts were used for the CVD growth of MWCNTs. The resulting materials were analysed by SEM and TEM, Raman and XRD to establish a relation between catalyst design and MWCNT yield. We show that our catalyst synthesis route leads to the formation of laminar non-porous catalyst systems, which at a calcination temperature of 800 ºC stabilise in a crystallographic phase of Me x Mg 1-x MoO 4 (Me = Co or Ni). We give evidence that increased MWCNT yields of more than 3000 wt% with