Crystal plane control of 3D iron molybdate and the facet effect on gas sensing performances

Facile synthesis of 3D flower-like Fe-2(MoO4)(3) with dominant exposed (100) facets has been achieved by adjusting pH and hydrothermal time. The 3D Fe-2(MoO4)(3) was characterized by X-ray diffraction, transmission electron microscopy, scanning electron microscopy, Raman spectroscopy, and nitrogen adsorption-desorption technique. Results demonstrated the 3D Fe-2(MoO4)(3) was mesoporous structures composed by nanosheets. As compared with the routine Fe-2(MoO4)(3) nanosheets, the synthesized Fe-2(MoO4)(3) with dominant exposed (100) facets shows excellent gas-sensing performance due to the high chemical activity of the exposed (100) facets. The enhancement in the gas-sensing performance suggests that the effect of exposed facet is dominant rather than the size effect, specific surface area. In addition, the 3D flower-like Fe-2(MoO4)(3) exhibits gas sensing selectivity to xylene, the selectivity should be originated from the surface structure of Fe-2(MoO4)(3) at the atomic level. Fe-2(MoO4)(3) has many Mo6+ active sites from Mo-O tetrahedrons on the surface, which act as catalyst for xylene absorbing and reacting with absorbed oxygen ion. The sensor based on the 3D flower-like Fe-2(MoO4)(3) is a promising candidate for fast, sensitive and selective detection of xylene. (C) 2017 Elsevier B.V. All rights reserved.