Phosgene Gas Sensing of Ti2CT2 (T = F−, O−, OH−) MXenes

Abstract

AbstractThe phosgene gas sensing properties of experimentally produced 2D titanium carbide MXenes with surface terminations (Ti2CT2: 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 Ti2CT2 MXenes. Pristine and defective Ti2C, Ti2CF2, and Ti2C(OH)2 show metallicity, making them ideal for gas sensing. Ti (C) vacancy defects in Ti2CO2, Ti2CF2, and Ti2C(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 Ti2C(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 Ti2C(OH)2 with Ti vacancy. The results elucidate that a Ti2C(OH)2 based sensor has a high potential for efficient reversible phosgene detection.