Tin sulfides heterostructure modified quartz crystal microbalance sensors with high sensitivity for hazardous trimethylamine gas

Abstract

P-type SnS and n-type SnS2 can form SnSx heterostructure and the unique structure has been proved to possess better sensing properties. In this work, a series of SnSx was synthesized by a one-step hydrothermal method at different S/Sn molar ratios. And the QCM transducer provided a platform for SnSx samples to realize high sensitivity detection of TMA gas at low concentration (below 10 ppm threshold limit). The TMA sensing sensitivity improved as the content of SnSx heterostructure increased in 40 % RH at 25 ℃. The SnSx prepared in the S/Sn ration of 6 exhibited the best sensitivity (−22.29 Hz/ppm), good selectivity and stability with the limit of detection (LOD) of 770 ppb, suggesting the TMA sensing enhancement of SnSx heterostructure. Density functional theory (DFT) simulations verified the improved sensing response of SnSx heterostructure was ascribed to the p-n junction and weak hydrogen bonds. This heterostructure may contribute to the further development of QCM gas sensors for TMA sensing in the monitoring of food freshness and environment.