Highly selective ppb-level H_2S sensor for spendable detection of exhaled biomarker and pork freshness at low temperature: Mesoporous SnO_2 hierarchical architectures derived from waste scallion root

摘要

Herein, we firstly reported a waste scallion root biotemplate strategy to massively fabricate mesoporous SnO_2 hierarchical architectures, which can realize precise detection of ppb-level H_2S gas in highly humid atmosphere (RH = 85%). The hierarchical skeleton is made up of the crosslinked nanoparticles of about 13 nm with a layer of nanospheres uniformly loaded on the surface of small-sized particles. Such specially structural characteristic can ensure that SnO_2 sensing materials possess large specific surface area and good mesoporous connectivity, enhancing the response and selectivity towards trace H_2S in a wide range of 0.5-1000 ppb at low working temperature of 92 'C. Especially, detection limit of 0.5 ppb is the lowest among all reported SnO_2-based H_2S sensors. Meanwhile, we also monitored the change of trace H_2S gas concentration in exhaled breath of healthy human, the decay process of fresh pork in 72 h and the simulated environment of halitosis under high humidity, and the sensor exhibited satisfactory results. Therefore, the mesoporous SnO_2 hierarchical structure could be used as a spendable sensing material of detecting ppb-level H_2S for the applications in meat freshness monitoring and halitosis diagnosis.