Exploring the Sensing Capabilities of Ti₃C₂T_X MXene Derived C/TiO₂: An Approach Toward Stable and Selective Hydrogen Gas Sensing

Titanium Carbide (Ti<sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub>C<sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub>), a 2D material discovered in 2011, has been investigated for various applications, and it’s 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 Ti<sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub>C<sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> 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 2D layered Carbon/TiO2 (C/TiO<sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub>) structures synthesized via controlled surface oxidation of Ti<sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub>C<sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub>T<sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">X</sub> MXene at 500°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°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 H<sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> sensing. This excellent selectivity and significant sensor response to H<sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> 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 Ti<sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub>C<sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub>T<sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">X</sub> MXene to C/TiO<sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> leads to formation of porous, high-surface-area nanostructure which enhances gas adsorption and desorption.