Polymer-derived nanoporous silicon carbide with monodisperse spherical pores

Abstract

The synthesis of polymer-derived nanoporous silicon carbide with monodisperse spherical pores is described. An incipient wetness method was used to fill the interparticle voids of microemulsion-derived silica nanospheres with the polycarbosilane SMP-10. The spheres have a very narrow diameter distribution in the mesoscale that could be replicated as pores of the silicon carbide materials by performing pyrolysis in an inert atmosphere and subsequent HF etching. Using a pyrolysis temperature between 973 K and 1573 K control of the pore sizes, the specific surface areas as well as the silicon carbide structure was achieved. Shrinkage of the system due to crystallization and structure transformations seems to occur. Even for temperatures as high as 1573 K SiC with uniform spherical pores and specific surface areas up to 433.1 m² g⁻¹ could be synthesized. This class of silicon carbides (named DUT-45, DUT = Dresden University of Technology) is characterized by unique nitrogen physisorption performance and small angle X-ray scattering curves.