SnO₂ Nanowire/MoS₂ Nanosheet Composite Gas Sensor in Self-Heating Mode for Selective and ppb-Level Detection of NO₂ Gas

The development of low-cost and low-power gas sensors for reliable NO₂ gas detection is important due to the highly toxic nature of NO₂ gas. Herein, initially, SnO₂ nanowires (NWs) were synthesized through a simple vapor–liquid–solid growth mechanism. Subsequently, different amounts of SnO₂ NWs were composited with MoS₂ nanosheets (NSs) to fabricate SnO₂ NWs/MoS₂ NS nanocomposite gas sensors for NO₂ gas sensing. The operation of the sensors in self-heating mode at 1–3.5 V showed that the sensor with 20 wt.% SnO₂ (SM-20 nanocomposite) had the highest response of 13 to 1000 ppb NO₂ under 3.2 V applied voltage. Furthermore, the SM-20 nanocomposite gas sensor exhibited high selectivity and excellent long-term stability. The enhanced NO₂ gas response was ascribed to the formation of n-n heterojunctions between SnO₂ NWs and MoS₂, high surface area, and the presence of some voids in the SM-20 composite gas sensor due to having different morphologies of SnO₂ NWs and MoS₂ NSs. It is believed that the present strategy combining MoS₂ and SnO₂ with different morphologies and different sensing properties is a good approach to realize high-performance NO₂ gas sensors with merits such as simple synthesis and fabrication procedures, low cost, and low power consumption, which are currently in demand in the gas sensor market.