Facile synthesis of 3D flowerlike á-FeOOH architectures and their conversion into mesoporous á-Fe_2O_3 for gas-sensing application

摘要

We reported a facile and efficient solution-based route to prepare novel flowerlike á-FeOOH architectures without any template or surfactant. Scanning electron microscope (SEM) images reveal that leaflike nanosheets with a thickness about 40 nm assembled into flowerlike superstructures. On the basis of time-dependent experiments, a multistage reaction mechanism for the formation of the flowerlike á-FeOOH was proposed. After heat treatment, the flowerlike á-FeOOH could be converted into corresponding mesoporous á-Fe_2O_3. Transmission electron microscopy (TEM) images and porosity analysis showed that the nanosheets have porous walls with a pore size of about 7 nm. As a demonstration of potential application for gas-sensing materials, the mesoporous á-Fe_2O_3 nanostructures exhibited short response/recovery time within 5/10 s, and low response concentration of 1 ppm toward acetone vapors. Large specific surface area and mesoporous structure should be beneficial for the sensing properties of á-Fe_2O_3.