Dual Improvement in Sensitivity and Humidity Tolerance of a NO₂ Sensor Based on 3-Aminopropyltriethoxysilane Self-Assembled Monolayer-Functionalized SnSe₂ for Explosive Photolysis Gas Detection

Explosives can be analyzed for their content by detecting the photolytic gaseous byproducts. However, to prevent electrostatic sparking, explosives are frequently preserved in conditions with low temperatures and high humidity, impeding the performance of gas detection. Thus, it has become a research priority to develop gas sensors that operate at ambient temperature and high humidity levels in the realm of explosive breakdown gas-phase detection. In this work, 3-aminopropyltriethoxysilane (APTES) self-assembled monolayer-functionalized tin diselenide (APTES-SnSe 2 ) nanosheets were synthesized via a facile solution stirring strategy, resulting in a room-temperature NO 2 sensor with improved sensitivity and humidity tolerance. The APTES-SnSe 2 sensor with moderate functionalization time outperforms the pure SnSe 2 sensor in terms of the response value (317.51 vs 110.98%) and response deviation (3.11 vs 24.13%) under humidity interference to 500 ppb NO 2 . According to density functional theory simulations, the stronger adsorption of terminal amino groups of the APTES molecules to NO 2 molecules and stable adsorption energy in the presence of H 2 O are the causes of the improved sensing capabilities. Practically, the APTES-SnSe 2 sensor achieves accurate detection of photolysis gases from trace nitro explosives octogen, pentaerythritol tetranitrate, and trinitrotoluene at room temperature and various humidity levels. This study provides a potential strategy for the construction of gas sensors with high responsiveness and antihumidity capabilities to identify explosive content in harsh environments.