Fluxing template-assisted synthesis of sponge-like Fe ₂ O ₃ microspheres toward efficient catalysis for CO oxidation

Constructing a porous architecture is a considerable strategy to enhance the catalytic activity of metal oxides catalysts for CO oxidation. In this work, we have developed porous sponge-like Fe ₂ O ₃ microspheres by employing a facile aerosol spray pyrolysis. The NaNO ₃ salt in the spray solution plays a crucial role as a fluxing sacrifice template in the formation of the sponge-like structure, in which a high surface area of 216.2 m ² g ⁻¹ and an average pore size of 4 nm are obtained. This novel Fe ₂ O ₃ catalyst exhibits an improved catalytic activity compared to usual iron oxides catalysts. Nearly 50% CO conversion at a relatively low temperature of 200 °C and 100% CO conversion at 300 °C at a space velocity of 60 000 ml h ⁻¹ g ⁻¹ are achieved. Furthermore, it displays an outstanding catalytic stability without distinct decay for 1000 min in a continuous stream at 300 °C. In addition to the effect of plentiful adsorption sites for the gas reactant, the promoted catalytic performance is also attributed to the function of abundant OH groups rooted in the large surface of the sponge-like structure, which induces faster reaction rate of CO oxidation via a bicarbonate route.