Templated synthesis of high surface area inorganic oxides by silica aquagel-confined co-precipitation

Abstract

A new and simple synthetic strategy for the preparation of high surface area nanosized metallic oxides using low cost precursors is described in this work. It is based on the coagulation – precipitation processes that occur when the metallic cations of salts dissolved in a silica aquagel medium are forced to precipitate by means of basic reagents. Nanoparticulate aggregates of the metallic oxides can then be obtained by applying the subsequent steps of drying, calcination and silica removal. Here, we illustrate the application of this technique by the preparation of both single and mixed metallic oxides such as copper oxide/ceria, hematite, cobalt ferrite and copper manganese spinel. The materials obtained in this way are made up by aggregates of nanosized particles (2–8 nm) and they exhibit very high surface areas up to 300 m2/g. Depending on the chemical composition of the oxides, different structures ranging from quasi-rounded nanoparticles to aggregates of needle-shaped nanoparticles were obtained.