Chemophysical acetylene-sensing mechanisms of Sb₂O₃/NaWO₄-doped WO₃ heterointerfaces

Sb2O3-loaded NaWO4-doped WO3 nanorods were fabricated with varying Sb contents from 0 to 2 wt% by precipitation/impregnation methods and their p-type acetylene (C2H2) gas-sensing mechanisms were rigorously analyzed. Material characterization by X-ray diffraction, X-ray photoelectron spectroscopy, scanning transmission electron microscopy and nitrogen adsorption indicated the construction of short NaWO4-doped monoclinic WO3 nanorods loaded with very fine Sb2O3 nanoparticles. The sensors were fabricated by powder pasting and spin coating and their gas-sensing characteristics were evaluated towards 0.08-1.77 vol% C2H2 at 200-350 °C in dry air. The gas-sensing properties of the NaWO4-doped WO3 sensor with the optimum Sb content of 1 wt% showed the highest p-type response of ∼250.2 to 1.77 vol% C2H2, which was more than 20 times as high as that of the unloaded one at the best working temperature of 250 °C. Furthermore, the Sb2O3-loaded sensor offered high C2H2 selectivity against CH4, H2, C3H6O, C2H5OH, HCHO, CH3OH, C8H10, C7H8, C2H4 and NO2. Mechanisms responsible for the observed p-type sensing and response enhancement behaviors were proposed based on the NaWO4-doped WO3-Sb2O3 (p-n) heterointerfaces and catalytic spillover effects. Consequently, the Sb2O3-loaded NaWO4-doped WO3 nanorods have potential as alternative p-type gas sensors for selective and sensitive C2H2 detection in various industrial applications.