Facile synthesis of α-Fe2O3@SnO2 core–shell heterostructure nanotubes for high performance gas sensors

Abstract

A facile hydrothermal method was employed to synthesize porous α-Fe2O3@SnO2 heterostructure nanotubes. The morphologies and structures of the as-prepared samples were characterized by field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), X-ray powder diffraction (XRD), and N2 adsorption–desorption techniques. The hollow α-Fe2O3 nanotubes with outer diameters of about 90nm were uniformly coated by a 10nm thick layer of SnO2 nanoparticles, demonstrating apparent heterostructures. The α-Fe2O3@SnO2 heterostructure nanotubes were applied to construct gas-sensor devices which exhibited high sensitivity, fast response–recovery, good selectivity and excellent repeatability to acetone. Because of the porous structure and large specific surface area, the heterogeneous core–shell nanocomposites show a markedly enhanced gas sensing performance in comparison with the initial α-Fe2O3 nanotubes and the pure SnO2 nanoparticles. For example, the sensitivity of the α-Fe2O3@SnO2 composites to 100ppm acetone can reach as high as 33.4 at the optimum operating temperature of 300°C, which was about twice of the value for pure α-Fe2O3 nanotubes and even up to 5-fold higher than that of pure SnO2 nanoparticles.