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

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 sensi-tivity improved as the content of SnSx heterostructure increased in 40 % RH at 25 degrees C. 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 func-tional 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.