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 CO2 gas sensors using a porous silicon/Mo2CTx hybrid system. The structure of the Mo–In–C non-MAX phase and formation of Mo2CTx 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 Mo2CTx MXene films. The uniform deposition of the layered sheet-like 2D Mo2CTx on the substrates was identified using the FESEM images. The sensor is found functional from room temperature to high-temperature conditions (30–250 °C). On the normal humid condition of 30% RH, the gas sensing response of the fabricated sensor is almost double in comparison with the crystalline silicon/Mo2CTx sensor at 250 °C. The introduction of humidity leads to further enhancement of the sensing response from 25% to 32%. Moreover, the fabricated sensor presents a good sensing response at room temperature (30 °C) for a CO2 concentration of 50 ppm along with a fast response and recovery times of 32 and 45 s with a high degree of stability.