Formation of mesoporous Co 3O 4 replicas of different mesostructures with different pore sizes

Abstract

Mesoporous metal oxides Co 3O 4 are prepared via hard templating synthesis method by using various mesoporous silicas with different pore size as templates. The pore size of the mesoporous silicas with the symmetry of two-dimensional (2d)-hexagonal p6 mm, bicontinuous cubic Ia 3 ¯ d and Pn 3 ¯ m have been controlled in the range of 6.6–10.7, 4.2–7.5 and 5.1–6.7 nm, respectively, by choosing different surfactants and co-surfactants and by adjusting either the aging temperature or the ionization degree of the surfactant. The pore size of the silica template has been considered to be an important factor that determines the mesostructure of the resulting metal oxides. It has been found that for p6 mm, it is easier to replicate the mesoporous symmetry at large size of mesopores. For Ia 3 ¯ d , at large-pore size two sets of bicontinuous meso-channels are replicated into mesoporous Co 3O 4, while small-pore Ia 3 ¯ d leads to replication of both one set and two sets of meso-channels. Co 3O 4 can replicate both one set and two sets of bicontinuous Pn 3 ¯ m meso-channels at all pore sizes that can be obtained (5.1–6.7 nm), indicating the existence of ordered complementary micropores within the silica walls.