Open-system nanocasting synthesis of nanoscale α-Fe2O3 porous structure with enhanced acetone-sensing properties

Nanoscale alpha-Fe2O3 with porous structure was synthesized via an open-system nanocasting method. Characterization of the crystal structures, morphologies, surface areas, and pore size distributions of the as-synthesized alpha-Fe2O3 by wide-angle and small-angle X-ray powder diffraction, scanning electron microscopy, transmission electron microscopy, and nitrogen physisorption analysis demonstrated that the nanoscale alpha-Fe2O3 synthesized in open system had a less crystallinity with average diameter of similar to 6.0 nm, higher BET specific surface area of 205.4 m(2) g(-1), and wider pore size distribution from similar to 2.2 nm to 15.7 nm compared with that of the mesoporous alpha-Fe2O3 synthesized in closed system. The gas-sensing measurement results revealed that the nanoscale alpha-Fe2O3 based gas sensor had a much better response to acetone than that of the device prepared from the mesoporous alpha-Fe2O3. A possible gas-sensing mechanism based on the alpha-Fe2O3 samples synthesized with different nanocasting systems was discussed in detail. Wide porous distribution of the nanoscale alpha-Fe2O3, as well as small particle size and high surface area are effective for gas molecules diffusion and formation of sufficient electron depletion area and result the enhanced sensor response, which suggests that it has great potential for practical applications in diabetes diagnosis. (C) 2014 Elsevier B. V. All rights reserved.