Construction of ANF-based flexible ammonia sensor with in-situ grown MXene@ZnO to achieve high response at room temperature

Flexible and wearable gas sensors are drawing more attention in monitoring air quality and human health. Concurrently, high response, low operation-temperature, and long-term stability are highly required for the gas sensors. Herein, an aramid nanofiber (ANF)-based ammonia (NH 3 ) flexible gas sensor with high response, room temperature stability and low detection limit was prepared. The competitive performances of the gas sensor were achieved by well-constructed MXene@ZnO heterojunctions on ANF aerogel. The obtained ANF/MXene@ZnO flexible gas sensor contributed to a response value of 1 ppm NH 3 as high as 150.7% at room temperature. Furthermore, the sensor also exhibited good long-term stability for 50 days. The excellent NH 3 sensing performances of the flexible ANF/MXene@ZnO sensor is attributed to its high surface area, abundant reaction sites, and the formation of MXene@ZnO heterojunction. The metal-like properties of MXene can provide a variety of electron transport channels, speeding up the electron transport rate. In addition, adsorption of more NH 3 molecules can also enhance the sensitivity of sensitive materials. According to our density functional theory calculations, the adsorption of NH 3 by MXene@ZnO in the materials we studied can reach −1.54 V. This indicates that MXene@ZnO has a strong affinity for NH 3 and can effectively capture NH 3 molecules and increase the response value. This work is expected to afford an effective strategy for designing high-performance flexible gas sensors at room temperature.