Enhanced Room-Temperature NH₃-Sensing Performance of Ti₃C₂T_<i>x</i> MXene Decorated with CeO₂ Nanoparticles

2D MXenes have garnered enormous interest in the field of gas sensing. Unfortunately, the low stability, long recovery time, poor selectivity, and vulnerability to oxidation have hampered further development. Herein, Ti3C2Tx MXene is incorporated with CeO2 nanoparticles to improve the detection of NH3. Compared with Ti3C2Tx and CeO2, the response of composite to 10 ppm of NH3 is enhanced by 180% and 714% at room temperature, respectively, in addition to the excellent selectivity, fast response, and recovery rate. Based on the first-principles calculation, the CeO2 nanoparticles form a multifunctional passivation layer to shield the MXene from oxidative degradation and also provide ample active sites to adsorb NH3 gas to enhance the sensing ability. The results reveal an effective means of designing and developing high-performance room-temperature ammonia sensors.