Highly Stable, Fast Responsive Mo2ctx Mxene Sensors for Room Temperature Carbon Dioxide Detection

MXenes are the emerging class of 2D materials with numerous applications such as in energy storage, biomedical, catalysis, gas sensing, etc. Among these, the gas sensing application of MXene materials is gaining attention due to their higher sensitivity towards various gases but is least explored. Herein we report the fabrication of highly sensitive CO 2 gas sensors using a porous silicon/Mo 2 CT x hybrid system. The structure of the Mo-In-C non-MAX phase and formation of Mo 2 CT x MXene were studied using X-ray diffraction. The elemental characterization through XPS and EDS confirms the presence of the functional groups and the deposition of the Mo 2 CT x MXene films. The uniform deposition of the layered sheet-like 2D Mo 2 CT x on the substrates was identified using the FESEM images. The sensor is found functional from room temperature to high-temperature conditions (30 to 250 o C). On the normal humid condition of 30% RH, the percentage sensitivity of the fabricated sensor is almost double in comparison with the crystalline silicon/Mo 2 CT x sensor at 250 o C. The introduction of humidity leads to further enhancement of the sensitivity from 25% to 32%. Moreover, the fabricated sensor presents a high sensing response of 1.14% at room temperature (30 o C) for a CO 2 concentration of 50 ppm along with a fast response and recovery times of 32 and 45 s with a high degree of stability