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

Sub-stoichiometric WO3-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 WO3-x phase upon gas sensing performance. High-quality WO3-x nanostructures with several x values (WO3, W19O55, W5O14, W18O49) were synthesized and used to fabricate H2S gas sensors. Temperature programmed desorption of oxygen (O-2-TPD) shows that oxygen absorption behaviors of the as-prepared WO3-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 WO3-x facilitate the ionosorption process and in turn enhance the performance of the gas sensor.