Creating oxygen vacancies on porous tungsten oxide nanospheres via one-step muffle calcination for ultra-fast detection of ppb-level hydrogen sulfide sensors

Abstract

Exploring the relationship between tungsten oxides with a controlled amount of oxygen vacancies and their gas-sensing properties with respect to hydrogen sulfide is interesting for developing excellent comprehensive gas-sensing performance materials with fast and accurate response. In this work, the WO3 nanoparticles with oxygen defective structure were synthesized by a straightforward one-step muffle calcining method. The WO3 nanoparticles prepared at the calcination temperature of 600 ℃ (Ov-WO3-600) display the high response value (2777) and ultra-fast response time (2 s) to 5 ppm hydrogen sulfide (H2S) at 100 ℃. Moreover, it also exhibits low practical detection limit (100 ppb), long-term stability, as well as remarkable admirable selectivity. The gas sensing mechanism can be explained by the fact that oxygen vacancies, as donor energy levels provide more electrons, increase the carrier mobility and narrow the band gap. This makes it easier for oxygen to capture electrons to form more adsorbed oxygen, which improves the gas sensing performance of WO3-based sensors. Hence, our study can offer guidance for the construction of fast and accurate sensing materials based on WO3.