Synergistic effects of SnO₂ and Au nanoparticles decorated on WS₂ nanosheets for flexible, room-temperature CO gas sensing

In this study, WS₂ nanosheets that are bare or decorated with Au, SnO₂, or a combination of Au and SnO₂ were realized on flexible polyamide substrates. The fabricated sensors were operated for CO gas sensing in applied-voltage-induced self-heating mode. Not only optimal applied voltage was varied for the sensing of different gases, but also that the sensors behaved uniquely in response to CO gas. In particular, the Au-SnO₂-co-decorated WS₂ nanosheet gas sensor under an optimized applied voltage of 4.7, displayed the highest response (R_a/R_g = 3.687–50 ppm CO gas) and the highest selectivity to CO gas among the different gas sensors investigated. Furthermore, the optimized gas sensor indicated good gas response under tilting, bending and stretching conditions. The formation of Au-WS₂ Schottky junctions, SnO₂-WS₂ heterojunctions and the role played by Au NPs in the catalysis CO gas were the most contributed effects to the sensing. The results obtained in this study provide new avenues towards fabrication of flexible, low power gas sensors using metal chalcogenides.