Nitrogen-Containing Gas Sensing Properties of 2-D Ti₂N and Its Derivative Nanosheets: Electronic Structures Insight

In this work, the potentials of two-dimensional Ti₂N and its derivative nanosheets Ti₂NT₂(T=O, F, OH) for some harmful nitrogen-containing gas (NCG) adsorption and sensing applications have been unveiled based on the quantum-mechanical Density Functional Theory calculations. It is found that the interactions between pure Ti₂N and NCGs (including NO, NO₂, and NH₃ in this study) are very strong, in which NO and NO₂ can even be dissociated, and this would poison the substrate of Ti₂N monolayer and affect the stability of the sensing material. For the monolayer of Ti₂NT₂(T=O, F, OH) that is terminated by functional groups on surface, the adsorption energies of NCGs are greatly reduced, and a large amount of charges are transferred to the functional group, which is beneficial to the reversibility of the sensing material. The significant changes in work function imply the good sensitivity of the above mentioned materials. In addition, the fast response time further consolidates the prospect of two-dimensional Ti₂NT₂ as efficient NCGs' sensing materials. This theoretical study would supply physical insight into the NCGs' sensing mechanism of Ti₂N based nanosheets and help experimentalists to design better 2-D materials for gas adsorption or sensing applications.