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

Abstract

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.