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

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 alpha-Fe2O3 quasi-single crystal hierarchical tubule simply derived from poplar branch. The mull-ordered hollow tubules calcined at 600 degrees C (Fe-600) are constructed from nano-lamellas assembled by cross-linked chains of similar to 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 degrees C, which is more twice than those of reported alpha-Fe2O3 sensing materials. Particularly, the detection limit of 1 ppb is the lowest in all reported alpha-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 alpha-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.