SrTiO3 passivated MXene (Ti3C2Tx) for efficient VOC detection in hazardous humid ambient

Abstract

Humidity interference is a crucial consideration in gas sensing technology for real-time applications. MXenes are new-age two-dimensional (2D) materials with unique properties making them promising candidates for gas sensors. However, the MXene surface with the hydrophilic functional groups (e.g., =O, –OH) is susceptible to water vapor. The passivation by a hydrophobic layer on MXene could be the best option to overcome humidity intrusion. We are introducing super hydrophobic SrTiO3 passivation on the MXene layer for humidity-tolerant volatile organic compound (VOC) sensing. Herein, 2D MXene (Ti3C2Tx) was physically oxidized at 350 °C for 24 h to create a TiO2 layer and subsequent coating of moisture-blocking SrTiO3 (STO) overlayer was achieved by hydrothermal route. Sensors were tested in different VOCs and showed the optimum results towards the acetone. The TiO2 formation in MXene enhanced the acetone sensing response (217%/50 ppm) compared to the pure Ti3C2TX MXene sensor (175%/50 ppm) in air at 150 °C. However, the MX and TiO2/MX sensors were lacking in the acetone sensing performance in a humid atmosphere (80% RH). STO/MX-12 h sensor showed outstanding moisture-resistant sensing behavior in humid atmospheres (0–80% RH). Apart from this, the STO/MX-12 h sensor showed a high response of 68% for 100 ppb of acetone with adequate repeatability, and excellent stability in 80%RH and 150 °C operating temperature. The hydrophilicity change in MXene after SrTiO3 passivation was optimized by contact angle study.