Fabrication of Delaminated 2D Metal Carbide MXenes (Nb<sub>2</sub>CT<i><sub>x</sub></i>) by CTAB-based NO<sub>2</sub> Gas Sensor with Enhanced Stability

Abstract

Sensitivity is the prime factor in solid-state gas sensors in terms of explicit noting of the change in signal. For achieving this, two vital prerequisites to be satisfied simultaneously: (i) electrical noise should be null and (ii) significant signal which is not met by the existing sensing materials. This study demonstrates that 2D metal carbide MXenes (Nb2CTx) have strong metal conductivity for noise reduction and abundant functional groups for detecting the signal toward higher sensitivity. This work shows successful exfoliation of Nb2CTx in the presence of cationic surfactants like cetyltrimethylammonium bromide (CTAB), which is significantly stable. The confirmation about the successful stabilization of Nb2CTx in DI water is obtained from material characterization and gas sensing observations. The experiments show that the dynamic sensing response of the Nb2CTx-CTAB sensor increases by approximate to 3 times for NO2 gas detection. The sensitivity of the Nb2CTx and Nb2CTx-CTAB found 0.543 and 1.686 ppm(-1), respectively, toward NO2 gas. Over time (up to 30 d), CTAB functionalized Nb2CTx MXene noticed trace-level detection capability with better environmental stability than pristine MXene. Herein, the obtained results show the gas sensing characteristics of Nb2CTx-CTAB and witness a selective and ultra-sensitive response toward NO2 gas detection.