General Synthesis of Periodic Macroporous Solids by Templated Salt Precipitation and Chemical Conversion

This paper presents a general method to prepare three-dimensionally ordered macroporous (3DOM) metal oxides or carbonates via templating with polystyrene (PS) spheres. The method is based on templated precipitation of metal salts (acetates, oxalates, oxides) within a colloidal crystal of PS spheres and subsequent chemical conversion of the inorganic precursors. The compositional range of possible macroporous products includes oxides or carbonates of many metals in the periodic table (e.g., MgO, Cr2O3, Mn2O3, Fe2O3, Co3O4, NiO, ZnO, CaCO3), including compositions that are less accessible or more expensive by previous syntheses based on metal alkoxide precursors. Optimal synthesis conditions and structural features of selected materials are described, on the basis of XRD, TGA, SEM, TEM, nitrogen adsorption data, and chemical analysis.