High-performance gas sensors based on the WO3-SnO2 nanosphere composites

WO3-SnO2 nanosphere (NS) composites with different structures and morphologies are successfully synthesized by a facial hydrothermal method. Two kinds of gas sensors were fabricated from WO3-SnO2 NS composites of hollow structure with average diameter of 360 nm and solid structure with average diameter of 42 nm by varying the synthesis temperature. The as-prepared composites were annealed at 500 degrees C for 4 h in atmosphere before the characterization and sensing performance test. The crystalline structures, morphologies and surface compositions of the annealed WO3-SnO2 NS composites are characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and X-ray photo-electron spectroscopy (XPS) techniques, respectively. The results of gas sensing tests show that WO3-SnO2 NS composites with hollow structure exhibit the superior sensing behavior, including sensitivity, response-recovery rate and selectivity, as compared to the composites with solid structure. The WO3-SnO2 NS composites presented in this work shows a high sensitivity, fast response and selectivity towards acetone. The surface conductivity changes of WO3-SnO2 NS induced by the surface gas adsorption and desorption is proposed to responsible for the corresponding sensing behaviors. The WO3-SnO2 NS composites with hollow structure presented in this study have potential practical applications in the field of gas sensor devices. (C) 2018 Elsevier B.V. All rights reserved.