CoTsPc assisted PANI functionalized Ti3C2Tx MXene gas sensor for ppb-level NO detection at room temperature

The massive emission of NO presents a significant risk to both human health and ecological systems. Given its strong reactivity and oxidizing properties, traditional NO gas sensors are no longer able to meet the growing demand for applications. Consequently, designing and developing room-temperature NO sensors with high response, low detection limit, and distinct selectivity is crucial. Herein, a MXene/CoTsPc-PANI gas sensor with excellent performance was constructed using a convenient and environmentally friendly aqueous phase synthesis strategy. It uses a few-layered Ti₃C₂T_x MXene as the conductive substrate material, and utilizes π-π and electrostatic bidirectional interactions to efficiently assemble Cobalt(II) tetra-β-sulfophthalocyanine-polyaniline (CoTsPc-PANI) into the MXene matrix. CoTsPc-PANI functionalized modification of MXene resulted in faster charge migration behavior, numerous active sites, and a significant specific surface area. In particular, the MXene/1.0CoTsPc-0.4PANI sensor exhibits extremely high NO sensitivity (LOD=45.8 ppb), unique selectivity (selectivity coefficient for NO₂ is 23.5), and high response (R_{(100 ppm NO)}= 244.7 %, 45, 24 and 31 times the response of MXene, PANI and CoTsPc sensors, respectively) at room temperature. At the same time, the MXene/1.0CoTsPc-0.4PANI sensor showed excellent accuracy in aiding the detection of NO content in vehicle exhaust (6.9 % relative error to measurements taken at automobile inspection stations). Finally, the MXene/1.0CoTsPc-0.4PANI flexible gas sensor exhibits the same excellent NO sensing performance as the above sensors (relative error <3.0 %). This study provides new ideas for designing MXene-based sensing materials with potential applications in automotive exhaust NO content detection and flexible gas sensors.