Phosgene Gas Sensing of Ti<sub>2</sub>CT<sub>2</sub> (T = F<sup>−</sup>, O<sup>−</sup>, OH<sup>−</sup>) MXenes
Siby Thomas, Mohsen Asle Zaeem
Abstract
Abstract The phosgene gas sensing properties of experimentally produced 2D titanium carbide MXenes with surface terminations (Ti 2 CT 2 : T = F − , O − , OH − ) are studied by first‐principles calculations. The effect of Ti and C vacancy defects, which are frequently created in synthesizing MXenes, on the structural, mechanical, electronic, and gas adsorption properties are studied to analyze the phosgene gas sensing performance of Ti 2 CT 2 MXenes. Pristine and defective Ti 2 C, Ti 2 CF 2 , and Ti 2 C(OH) 2 show metallicity, making them ideal for gas sensing. Ti (C) vacancy defects in Ti 2 CO 2 , Ti 2 CF 2 , and Ti 2 C(OH) 2 cause an increase (decrease) in work function, resulting in enhanced interaction between the MXene surface and a gas molecule. When a phosgene gas molecule is exposed on the surface of MXenes, only Ti 2 C(OH) 2 shows stable adsorption and charge transfer. An ultra‐low recovery time, the time between adsorption and desorption of a phosgene gas molecule, is achieved for both pristine and defective Ti 2 C(OH) 2 with Ti vacancy. The results elucidate that a Ti 2 C(OH) 2 based sensor has a high potential for efficient reversible phosgene detection.