Phase Engineering of SnSe (X = 1,2) Microstructures for High-Performance NO Chemiresistive Room-Temperature Sensor Systems: Toward Highly Reliable and Robust Detection Properties under Humidity and Interfering Gas Conditions.

Two-dimensional SnSe (X = 1, 2) has emerged as a promising candidate for a NO chemiresistive sensor due to a remarkable affinity to NO gas adsorption. Although their gas sensing mechanism primarily relies on direct charge transfer, the underlying mechanisms of SnSe and SnSe remain unclear, despite various reported successes in phase engineering of SnSe. Here, we investigate phase engineering of SnSe in a hydrothermal route via 1-dodecanethiol (1-DDT), which served as a phase stabilizer, and comprehensively demonstrate phase-dependent NO detection properties. As the 1-DDT concentration increases, we directly confirm that the SnSe structure was gradually transformed to the SnSe one. This transformation correlates with a gradual increase in NO gas responses from 45 to 1430%, the highest value reported among SnSe-based NO gas sensors. The obtained SnSe-based sensors also exhibit a good NO discrimination without configuration of sensor arrays, under an interfering gas atmosphere in humidity conditions. Our computational calculation also unveils that these outstanding detection performances are attributed to well-constructed SnSe coupled with a single Se vacancy to enhance a stronger NO adsorption than SnSe. Finally, we demonstrate a sensor module system based on SnSe, enabling real-time monitoring of NO gas.