Improving gas sensing performance by oxygen vacancies in sub-stoichiometric WO3−x

Abstract

Sub-stoichiometric WO_3−x has provided an alternative platform to investigate oxygen vacancies in gas sensors based on metal-oxides. We present an experimental study on the influence of sub-stoichiometric WO_3−x phase upon gas sensing performance. High-quality WO_3−x nanostructures with several x values (WO₃, W₁₉O₅₅, W₅O₁₄, W₁₈O₄₉) were synthesized and used to fabricate H₂S gas sensors. Temperature programmed desorption of oxygen (O₂-TPD) shows that oxygen absorption behaviors of the as-prepared WO_3−x nanostructures are affected by oxygen vacancies, which played a critical role in the detection of H₂S at varying temperature range. We find that oxygen vacancies in sub-stoichiometric WO_3−x facilitate the ionosorption process and in turn enhance the performance of the gas sensor.