The Key Role of Nanocasting in Gold-based Fe2O3 Nanocasted Catalysts for Oxygen Activation at the Metal-support Interface

The total oxidation of propane, a representative Volatile Organic Compound, has been studied using gold-based alpha-Fe2O3 catalysts. Catalysts consisting of gold nanoparticles confined in nanostructured Fe2O3 prepared by a nanocasting route present the highest catalytic activity for propane total oxidation, and the activity is significantly greater than those of gold-based catalysts where iron oxide supports are prepared by other conventional methods, such as calcination. Detailed characterisation and Density-functional theory (DFT) studies have been undertaken in order to explain the enhancement in catalytic properties. The presence of confined gold nanoparticles on the nanocast Fe2O3 facilitates the production of highly reactive oxygen vacancies at the metal-support interface, increasing the catalyst performance. Both the development of a microporous/mesoporous structure in the iron oxide support and the presence of a mixed surface phase of Si and Fe oxides, seem to be key parameters, being both features inherent in the nanocasting process from silica templates. Additionally, the catalytic activity is enhanced due to other positive effects, which are closely related to the nanocasting preparation method: i) a higher contact surface area between partially confined small gold nanoparticles in the internal mesoporosity of the nanostructured support and the metal oxide and; ii) a more reducible support due to the presence of more active surface lattice oxygen.