A spendable gas sensor with higher sensitivity and lowest detection limit towards H2S: Porous α-Fe2O3 hierarchical tubule derived from poplar branch

Abstract

Abstract Development of ppb-level H2S sensors based on semiconductor metal oxides has been highly desirable due to its harmful to the human health even at a concentration as low as 20 ppb. In this work, we reported a spendable and high-performance ppb-level H2S gas sensor based on porous α-Fe2O3 quasi-single crystal hierarchical tubule simply derived from poplar branch. The multi-ordered hollow tubules calcined at 600 °C (Fe-600) are constructed from nano-lamellas assembled by cross-linked chains of ~35 nm nanoparticles with amounts of meso- and macro-pores. The Fe-600 sensor with short response time has higher sensitivity of 24.3 to 10 ppm H2S at low working temperature of 133 °C, which is more twice than those of reported α-Fe2O3 sensing materials. Particularly, the detection limit of 1 ppb is the lowest in all reported α-Fe2O3-based sensors. Furthermore, the result of the Fe-600 sensor in monitoring the freshness of pork is satisfied. The sensing mechanism indicates that such good response towards H2S gas is mainly ascribed to the inherent characteristics of porous α-Fe2O3 hierarchical tubules, surface adsorbed oxygen species and formation of metastable iron sulfide caused by lattice oxygen. The Fe-600 sensing material with outstanding combination performances could be used as a good candidate for application in detecting trace ppb-level H2S.