Exploring the gas sensing performances of O-functionalized TiVC MXene: mechanistic insights from computations

The detection of toxic gases remains a critical challenge for environmental safety, and MXenes have rapidly emerged as innovative materials for sensor development. In this work, we break new ground by exploring the sensing capabilities of O-functionalized TiVC MXene, a material not yet studied for gas sensing applications. <i>Ab initio</i> molecular dynamics (AIMD) simulations confirm the monolayer's dynamical stability at 300 K. Using first-principles-based DFT calculations, we systematically analyze the interaction of H₂, CO, NO, NO₂, and SO₂ gas analytes with the TiVCO₂ surface. Our study highlights key parameters such as adsorption strength, charge transfer, change in work function, and gas desorption time, critical to sensitivity and selectivity-core elements of the 4-S principle (sensitivity, selectivity, stability, and speed). The robust interaction energies (≤-48 kJ mol^-1), short interaction distances, and significant charge transfer suggest that NO adsorption on TiVCO₂ is characterized by strong physisorption, governed by hybridization of the 3d-orbitals of titanium and vanadium with the p-orbital of nitrogen. Notably, the change in work function upon interaction comes out to be >0.1 eV and the calculated desorption time of NO at 300 K is 1.74 s, making this MXene a highly promising candidate for NO gas detection at room temperature. Other gases exhibited much weaker physisorption with nanosecond desorption times, reinforcing the selective nature of TiVCO₂ for NO detection. These findings offer insights into the use of O-functionalized TiVC MXene for gas sensors, with the potential to revolutionize the design of high-performance sensing devices in environmental monitoring and industrial applications.