Influence of Fe Doping on Structure and Water Oxidation Activity of Nanocast Co₃O₄

Herein, we demonstrate that a perfect replication of a desired composition is not only related to the degree of interconnectivity of the double gyroid ordered mesoporous silica template, there is also an enormous effect from the nature of precursor and its composition. For the first time, the symmetry of ordered mesoporous Co 3 O 4 was tuned with iron doping by using the same batch of cubic ordered mesoporous silica (KIT-6) as a hard template. Nanocasting of the pure Co 3 O 4 results in a negative replica of the silica template that has a monomodal pore size distribution and a dense coupled structure, while incorporation of a small amount of iron lowers the mesostructural symmetry and alters the pore system of the replica. The effect of this remarkable observation was further investigated for electrochemical water oxidation where superior catalytic activities were observed when Co 3 O 4 was doped with small amounts of iron. Furthermore, iron incorporated Co 3 O 4 indicated comparable water oxidation activity with noble metal and cobalt based electrocatalysts. This kind of abundant transition metal based mesostructured material has the potential to be used as promising electrocatalysts for water oxidation.