Direct soft-templating route to crystalline mesoporous transition-metal oxides

A direct and general soft-templating method has been developed to prepare crystalline mesoporous transition metal oxides. The method was versatile and simple. Several crystalline mesoporous transition metal oxides have been successfully synthesized, such as Nb₂O₅, Ta₂O₅ and α-Fe₂O₃. The porous structure, and crystallinity of as-synthesized metal oxides were characterized by XRD, TG-DTA, SEM, TEM and N₂ sorption techniques. The crystallization of amorphous metal oxides resulted in the decrease of specific surface area due to the condensation of related amorphous metal oxide species and crystallite growth. At the same time, the pore volume was well maintained, which means the limited volume shrinkage. The pore size increased with the increasing of calcination temperature due to the growth of grain size and small pores emerged into larger ones. The as-synthesized metal oxides not only had clear mesostructure but also high crystallinity. Notably, all the reagents were commercial available and used without any treatment. It can be easily reproduced by researchers even without any experience in sol-gel related synthesis.