FePt(L10)@MWCNTs/Ru(NPs): A smart nanocomposite for catalysis applications.

Heterogenic catalysis is frequently carrying out with heavy metals, which are generally expensive and pollutants. The problems increase if the catalysts are used at nanometric scale because it is easier to lost material during the working cycle. This problem has doubled if we also consider the environmental pollution cost due to the nature of the metals and the nanoparticles (NPs) pollution (see asbestos problems). Usually, nanometric metal catalyst is supported on inert material like alumina or silica. In the last ten years carbon nanotubes (CNTs) have been also used as support in catalysis research. CNTs are one o more graphene rolled sheets. This structure allows having an empty internal cavity and an external wall. Often, CNTs support metal NPs on the external side and the empty nanocavities could be used to add other property to get a very smart new nanocomposite with more peculiar properties. Therefore, CNTs could be decorating with metals NPs outside and magnetic NPs inside. The magnetic character could be exploited: i) to move the nanometric catalyst by applying a magnetic field gradient, ii) to locally increase the temperature by applying a AC magnetic field, saving energy to heating the whole reactor. In this work the authors describe a new synthesis method to produce a three blocks nanocomposite formed of FePt NPs (L10 phase) inside, and Ru NPs outside MWCNTs and indicate as: FePt(L10)@CNTs/Ru(NPs), with out mix the different nanoparticles. In this nanocmposite the catalytic and magnetic property are together available. The products are characterized by TEM, HRTEM, SEM, XRD and magnetic measurements. To the best of our knowledge this is the first case of this kind of three block nanocomposite based on CNTs, and because to fill the cavity the author used a general wet method, and a lot of decoration methods are proposed in the literature and can be used here, our method can be considered a general wet method to get this three block nanocomposites. The property of separate nanoparticles and CNTs can be combined in many ways as: catalytic-magnetic, catalytic-optics, optics-magnetic or other and could be useful in many applications like medicine, electronics or energy. [1] M. Auffan et al. Nanomedicine 5, 999 (2010) [2] S. Iijima. Nature 354, 5, 6(1991) [3] H. Chu et al, Coordination Chemistry Reviews 254, 1117 (2010) [4] A. Capobianchi et al, Chem. Mater. 21, 2007(2009) [5] A. Capobianchi et al, Carbon 45, 2205(2007)