Exploring the Sensing Capabilities of Ti3C2TX MXene Derived C/TiO2: An Approach Toward Stable and Selective Hydrogen Gas Sensing

Titanium carbide (Ti3C2), a 2-D material discovered in 2011, has been investigated for various applications, and is to its potential as a gas sensor is exploring widely. However, to serve effectively in the field of gas sensing, it is essential to ensure long-term stability, which involves maintaining a consistent and repeatable output over time. Multiple studies have observed the degradation of MXene, particularly the surface oxidation of Ti3C2 to TiO2 in the presence of moisture, highlighting the necessity of in-depth research in this field. This work primarily focused on the stability analysis of MXene-based gas sensors. Additionally, we demonstrated that 2-D layered carbon/TiO2 (C/TiO2) structures synthesized via controlled surface oxidation of Ti3C2TX MXene at $500~^{\circ }$ C are stable as a gas sensor and can effectively detect hydrogen at low ppm levels. By utilizing this approach, the sensor achieved a remarkable response of 93% (in 65% relative humidity), with a response time of 45 s and a recovery time of 20 s at $300~^{\circ }$ C operating temperature. Furthermore, the selectivity of the prepared sample is compared with 100-ppm CO, 250-ppm NH3, and 10000-ppm CH4, indicating that oxidized MXene is a promising candidate for real-time H2 sensing. This excellent selectivity and significant sensor response to H2 make it well-suited for leak-detection applications. An attempt was also made to correlate the stable hydrogen sensing mechanism with the help of material characterization, which suggests that the oxidation of Ti3C2Tx MXene to C/TiO2 leads to the formation of porous, high-surface-area nanostructure, which enhances gas adsorption and desorption.