Doping & decoration of carbon based nanoparticles: applications in flame retardancy and catalysis

Mención Internacional en el título de doctorThe present work involves two main parts that will be explained after introduction. A brief introduction about history, properties, synthesis and characterization of carbon nanotubes, graphene and their nanocomposites and nanohybrides will be presented. The first part of the thesis is focused on the synthesis of different types of nanotubes: pristine carbon nanotubes (CNT), oxygen doped carbon nanotubes (COx), and nitrogen doped carbon nanotubes (CNx) by CVD method. The structure of the nanotubes were confirmed by XRD, XPS, SEM, TEM, TGA and Raman spectroscopy (Chapter 2). The most important difference between the synthesized nanotubes was their aspect ratio which is calculated from 1500-3000 for CNx to COx. Pristine CNT shows the aspect ratio about < 2000. Subsequently, the epoxy nanocomposites at 2 wt.% constant loading of carbon nanotubes (CNT, COx and CNx) and Diglycidyl ether bisphenol-A (DGEBA) as a good example of thermosetting polymer were have been prepared by three roll milling and cured by 4,4′- Diamio diphenyl sulfone (DDS) as a hardener. The thermal degradation of epoxy nanocomposites as well as glass transition temperatures and elastic moduli were measured by TGA, DSC and DMTA. The flammability of epoxy nanocomposites was studied by microscale combustion calorimetry (MCC) and limiting oxygen index (LOI) determination. Results showed that the fire retardant properties of nanocomposites improved significantly specially for COx, which presented a very high LOI (35%) and a homogeneous and uniform surface after burning. This effect was attributed to the very high aspect ratio of COx tubes. The results showed that introduction of the nanofillers at 2 wt.% loading caused the earlier initial decomposition of the nanocomposites, an increased char yield, and a reduction of the degradation rate of in comparison with pure epoxy. The influence of addition of nanofillers on the relaxational and mechanical behavior of nanocomposites was evaluated by DSC and DMTA. No significant variations in Tg, storage modulus or loss tangent width were detected, indicating that the addition of nanofillers does not negatively affect the relaxational and mechanical response of the nanocomposites (Chapter4). In the second part of our work, different copper nanocomponents were synthesized and decorated on graphene oxide by our microwave-assisted method. Copper hydroxyl nitrate double salt (DS) (Cu2(OH)3(NO3) and cuprous oxide (Cu2O) by changing the solvent in a very simple procedure were obtained from copper nitrate. Copper nitrate (CuO) and metallic copper can prepared from heating and reduction by ascorbic acid of DS, respectively. The four copper salts have been decorated on graphene oxide GO following the same microwave-assisted method. (Chapter 3) The performance of copper salts/GO nanohybrids as photocatalyst in degradation of one common dyes (Rhodamine B) has been studied. As we expected, incorporation of copper oxides (copper with different oxidation number) onto GO via our method resulted in enhancing the properties of initial metal oxides and it was comparable with the CuO and Cu2O/GO hybrids produced of conventional methods Photocatalytic activity of DS alone and decorated on GO has been reported for the first time in this work. In the last part of the thesis, we have checked the performance of decorated copper salts as catalyst in some common organic reactions like: C-C , C-N, and C-S coupling and oxidation of aldehyde (Chapter 6). The catalytic application of DS is introduced for the first time here. The results open up the possibility of a more thorough study of the catalytic performance of the supported copper double salt in other conditions which may be applied in the future for different catalytic and consecutive processes of organic synthesis.El presente trabajo incluye dos bloques principales que se explicarán después de la introducción. Empezaremos con una breve introducción sobre la historia, propiedades, síntesis y caracterización de los nanotubos de carbono, el grafeno y sus nanocompuestos y nanohíbridos. La primera parte de la tesis se centra en la síntesis de diferentes tipos de nanotubos: nanotubos de carbono prístinos (CNT), nanotubos de carbono dopados con oxígeno (COx) y nanotubos de carbono dopados con nitrógeno (CNx) por el método CVD. La estructura de los nanotubos se confirmó mediante espectroscopía XRD, XPS, SEM, TEM, TGA y Raman (Capítulo 2). La diferencia más importante entre los nanotubos sintetizados fue su relación de aspecto que se calcula de 1500-3000 para CNx y COx. Los CNT prístinos muestra una relación de aspecto de