High-sensitive ppb-level ammonia QCM sensor based on sulfur doped Ti3C2Tx MXene

This paper demonstrates chemi-resistive type and QCM ammonia sensors based on Ti 3 C 2 T x MXene with surface engineering. The morphology and structure composition of Ti 3 C 2 T x MXene were completely tested by XRD, SEM, TEM and Raman. The ammonia sensing performance of Ti 3 C 2 T x MXene sensors at room temperature were systematically studied. The QCM sensors show better performance towards ammonia than chemi-resistor sensors. The Ti 3 C 2 T x -S QCM sensor possesses quite sensitivity (49 Hz@100 ppb), high response/recovery capability (33 s/58 s) and good selectivity . XPS was introduced for the surface element status for the potential ammonia adsorption mechanism. It can be mainly related to for lowest average potential for reaction of Ti-S and the additional absorption towards the product nitric oxides enhancing the frequency shift by absorption mass increasing. This work confirms that surface engineering of Ti 3 C 2 T x MXene to be effective method for enhancing gas sensing performance, and the sensor shows potential application for low concentration ammonia sensing.