DFT study of NH3 adsorption on 2D monolayer MXenes (M2C, M = Cr, Fe) via oxygen functionalization: Suitable materials for gas sensors

• Published in: FlatChem 2022-01, Vol.31, p.100329, Article 100329
• Main Authors: Banu, A. Aseema, Sinthika, S., Premkumar, S., Vigneshwaran, J., Karazhanov, Smagul Zh, Jose, Sujin P.
• Format: Article
• Language: English
• Subjects: 2D layered Transition-metal carbide; Cr2C MXene; DFT calculations; Fe2C MXene; Gas sensor; NH3 adsorption
• ISSN: 2452-2627; 2452-2627
• DOI: 10.1016/j.flatc.2021.100329

[Display omitted] •The structural stabilities of the M2C and M2CO2 (M = Cr or Fe) MXenes were investigated through formation energy.•Ammonia adsorption energies were calculated as demonstrators of the gas sensor.•Bader charge analysis indicates the charge transfer between MXenes and adsorbed NH3.•DOS reveals the magnetic and metallic nature of the NH3/M2C or NH3/M2CO2. This work deals with the kind of the interaction of NH3 molecules adsorbed on the MXene layers. The adsorption energies of NH3 on the surface of MXenes (M2C, M = Cr and Fe) and their oxygen-functionalized forms (O-MXenes or M2CO2) were calculated by using the density functional theory. DFT-D4 calculations have revealed that the on-top sites are initiated for adsorption of NH3 on M2C and M2CO2. For the reaction on Cr2CO2, the Ead is found to be −0.29 eV lower than Cr2C and also the same tendency was achieved in Fe2C and its O-terminated MXene. This suggests that the molecule will strongly adsorb on Cr2C than its O-terminated surface. Bader charge analysis in terms of the induced net charges on M2C MXenes suggests that electron density distribution between N of NH3 (negatively charged) and the Cr/Fe (positively charged) surface would play a key role in the adsorption. Furthermore, DOS calculations reveal that the electrical conducting behaviour and magnetic nature of MXenes make them suitable for gas sensors applications.