Carbon nanotubes prepared in situ in a cellular ceramic by the gelcasting-foam method

The synthesis of carbon nanotubes from an oxide solid solution foam is reported for the first time. A foam of Mg0.9Co0.1Al2O4 solid solution is prepared by the gelcasting-foam method using notably mono- and di-functional acrylate monomers. Using a surfactant in the alkylpolyglucoside family allows to prevent structure changes in the foam before the onset of polymerisation. The wet ceramic foam is dried in air, producing a foam with an open porosity. Total porosity is equal to about 98% and the diameter of the pores is in the range 25–300 μm, about 90% being smaller than 200 μm. The Mg0.9Co0.1Al2O4 foam is reduced in H2–CH4 atmosphere, giving rise to a CNTs–Co–MgAl2O4 composite foam. Using the foam instead of the corresponding powder allows a four-fold increase in the production of carbon nanotubes, more than 95% of which have only 1 (70%) or 2 walls.