Electronic, Optical and Thermoelectric Properties of Two-Dimensional Molybdenum Carbon Mo 2 C-MXenes.

We investigate the structural, electronic, optical, and thermoelectric properties of three compositions of Mo₂C-MXenes (Mo₂CF₂, Mo₂C(OH)₂, and Mo₂CO₂) from monolayer to multilayer by first principles calculation within Density Functional Theory (DFT) and Boltzmann transport theory. Firstly, the atomic structures of Mo₂C-MXenes are optimized, and their respective structures are created with comparative research. Secondly, their electronic band structures and optical properties are studied in detail. The estimation of the bandgap energy of Mo₂C-MXenes with its functionalization reveal that most Mo₂CF₂ and Mo₂C(OH)₂ layers are semiconductors, while Mo₂CO₂ behaves as a metal. The electrical and optical properties can be altered by controlling the on-surface functional groups and the number of layers. Computation of the thermoelectric (TE) properties of Mo₂C-MXenes reveals that, upon heating to 600 K, Mo₂CF₂ and Mo₂C(OH)₂ exhibit a high Seebeck coefficient and a relatively high electrical conductivity. The Seebeck coefficient reaches ~400 µV K⁻¹ at room temperature for all layers of Mo₂CF₂ MXenes. Our results prove that Mo₂CF₂ is considered a promising material for thermoelectric devices, while Mo₂CO₂ does not possess better thermoelectric performance. Mo₂C-MXenes from monolayer to multilayer have outstanding properties, such as flexible bandgap energy and high thermal stability, making them promising candidates for many applications, including energy storage and electrode applications. [ABSTRACT FROM AUTHOR]