Ionic Liquid‐Mediated α‐Fe₂O₃ Shape‐Controlled Nanocrystal‐Supported Noble Metals: Highly Active Materials for CO Oxidation

Shape‐controlled iron oxide nanocrystals were prepared by using an ionic liquid‐mediated hydrothermal process. Different morphologies can be synthesised, such as cubes and porous nanotubes. Owing to the different morphologies developed, accessible surface area varies from a few m 2 g −1 to more than 50 m 2 g −1 . These differences result in different oxygen mobilities, and the porous nanorods demonstrate the highest bulk oxygen mobility. Thus, all these shaped materials demonstrate higher activity for the oxidation reaction compared to the commercial reference. In addition, the favourable physical properties, that is high surface area, enable the easy dispersion of noble metal nanoparticles (platinum, palladium and gold); some of these high‐surface area noble metal‐containing materials demonstrate remarkable catalytic activities. Porous nanorod‐supported gold nanoparticles enable the conversion of CO below 100 °C, which is far better than on commercial α‐Fe 2 O 3 ‐supported gold for which dispersion of gold remains difficult owing to the low surface area of the commercial support.