Self-assembled In2O3 truncated octahedron string and its sensing properties for formaldehyde

In this work, a continuous two-step route consisting of ammonolysis and re-oxidation process was developed for the growth of a novel In2O3 truncated octahedron string morphology. The as-synthesized products were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), and transmission electron microscopy (TEM), results of which indicated that the truncated octahedron strings were self-assembled by In2O3 crystals, and several tens of micrometers along their longitudinal axes. In addition, a gas sensor based on as-synthesized In2O3 truncated octahedron strings was fabricated using a ceramic tube as substrate in an in situ deposition manner. The sensor exhibited good selectivity toward formaldehyde, and showed a significant response for formaldehyde at a concentration lower to 5 ppm. The present study may serve as a basis for designing other novel morphology from semiconductor oxides for gas-sensing applications. (C) 2014 Elsevier B.V. All rights reserved.