Vapor-Phase Amine Intercalation for the Rational Design of Photonic Nanosheet Sensors

The development of vapor sensors with tunable sensitivity and selectivity is highly desirable because of the manifold applications ranging from air quality monitoring to food control. The design of such sensors remains, however, a great challenge. Here, we address this challenge by intercalating primary and tertiary alkylamines with varying alkyl chain lengths into H₃Sb₃P₂O₁₄ nanosheet-based Fabry-Pérot interference sensors. As the sensors are photonic in nature, the different amines can be distinguished based on their intercalation time and optical shift. Since the amines are protonated during intercalation and therefore trapped, this allows us to use amine modification as the basis for creating optical sensors. Intercalation of different amines gradually and widely tunes the sensor's sensitivity and selectivity to various analytes. This adjustment of sensing properties allows us to construct a sensor array on a single chip, which can distinguish different volatile organic compounds. The color change of this sensor array upon exposure to solvent vapors can be tracked with the naked eye, making this system a promising platform for the high-fidelity identification of volatile compounds. The sensor design protocol presented herein is straightforward and robust and can be transferred to other nanosheet-based devices for the rational tuning of their vapor-sensing properties and beyond.